tag:theconversation.com,2011:/id/topics/algae-1395/articlesAlgae – The Conversation2023-10-15T23:27:42Ztag:theconversation.com,2011:article/2113562023-10-15T23:27:42Z2023-10-15T23:27:42ZSlime after slime: why those biofilms you slip on in rivers are vitally important<figure><img src="https://images.theconversation.com/files/543180/original/file-20230817-5739-1dr1ti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>You might have noticed it after sliding on a rock in a Melbourne creek. Or it could have been wading through a Northern Territory waterhole. It’s slime, and our rivers are full of it. That’s a good thing. </p>
<p>Wherever there are hard surfaces like snags and rocks in our rivers, you’ll find slime. Or, as ecologists call it, <a href="https://en.wikipedia.org/wiki/Biofilm">biofilm</a>. Biofilms consist of communities of microorganisms that include algae, cyanobacteria, bacteria, fungi and protozoa. Together, they’re fixed in a matrix of natural polymers made by bacteria and other tiny creatures. It’s this matrix which gives the slippery, slimy texture we encounter when swimming in rivers. </p>
<p>Biofilms play an important role in our freshwater ecosystems. They underpin healthy rivers by forming the base of freshwater <a href="https://flow-mer.org.au/basin-theme-food-webs-water-quality/">food webs</a>. </p>
<p>Our <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.4680">new research</a> explores how these common but unsung communities change over time. We found that biofilms are most nutritious when new – less than six weeks old. After that, their food value declines. </p>
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<a href="https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="biofilm and algae from river" src="https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543184/original/file-20230817-28-xdh60x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">This is what a 73-day-old biofilm looks like after being pulled from a lowland river.</span>
<span class="attribution"><span class="source">Author provided</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Why are biofilms important?</h2>
<p>Without slime, rivers would lack a fundamental source of food for animals. That sounds like a big statement, but <a href="https://onlinelibrary.wiley.com/doi/full/10.1046/j.1442-8903.2001.00069.x">it’s true</a>. </p>
<p>Algae take energy from the sun and convert it into new biomass through <a href="https://education.nationalgeographic.org/resource/photosynthesis/">photosynthesis</a>. Bacteria and fungi break down organic debris, from dead leaves to dead fish, and recycle the nutrients. Tiny invertebrate grazers such as <a href="https://en.wikipedia.org/wiki/Zooplankton">zooplankton</a> and <a href="https://www.mdfrc.org.au/bugguide/">macroinvertebrates</a> feed on biofilms. In turn, they become food for larger predators such as fish, platypus and turtles. </p>
<p>Not all biofilms offer the same quality of food. And different communities of biofilm grow under different physical conditions.</p>
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Read more:
<a href="https://theconversation.com/life-on-earth-was-nothing-but-slime-for-a-boring-billion-years-23358">Life on Earth was nothing but slime for a 'boring billion' years
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<p>When the water level goes up in a river, rocks and dead trees at the surface are submerged and biofilms colonise this new habitat. It happens very quickly. Bacteria arrive first, followed by algae in the next few weeks. </p>
<p>Biofilms undergo natural changes in community composition over time, influenced by physical disturbance (such as scouring when water flow is high, or sedimentation from low flows) or chemical changes, such as additional nutrients from runoff. </p>
<p>These disturbances often lead to periods of collapse and recolonisation by new organisms. Biofilms are thought to become a poorer source of food for animals as they get older. That’s because older biofilm communities become dominated by <a href="https://en.wikipedia.org/wiki/Cyanobacteria">cyanobacteria</a> and <a href="https://en.wikipedia.org/wiki/Spirogyra">filamentous algae</a>, which aren’t as nutritious as a food for animals.</p>
<h2>So what makes good slime?</h2>
<p>For the discerning invertebrate, the best biofilm is one containing lots of algae – especially <a href="https://en.wikipedia.org/wiki/Diatom">diatoms</a> and green algae. These are rich sources of <a href="https://onlinelibrary.wiley.com/doi/10.1111/brv.13017">omega 3 fatty acids</a>, molecules essential for animal growth and reproduction. (That’s why the food supplement industry likes to sell us products rich in omega 3s). </p>
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<a href="https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="mayfly nymphs" src="https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=671&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=671&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=671&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=843&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=843&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550505/original/file-20230927-23-nmf7ax.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=843&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Mayfly nymphs, such as this <em>Offadens</em> spp. (Baetidae) scrape algae and fine detritus from submerged rocks, wood and macrophytes in rivers.</span>
<span class="attribution"><span class="source">Chris Davey</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Having high quality food is one thing. But the food also needs to be easy to get. In the study of food webs, we often use a theory called <a href="https://encyclopedia2.thefreedictionary.com/ecological+energetics">ecological energetics</a>. Put simply, this suggests the success of an animal population is limited by how hard it is for individuals to obtain sufficient <a href="https://onlinelibrary.wiley.com/doi/10.1111/fwb.13895">food for growth</a> and reproduction. </p>
<p>You might have long-chain omega 3 fatty acids present, but buried under a pile of less edible microorganisms and detritus. The effort may simply not be worth the reward. </p>
<p>To date, we have a poor understanding of when biofilms hit their peak food value for animals. That’s what we set out to find. </p>
<h2>What did we find?</h2>
<p>Many of our rivers are regulated by dams and weirs. That means we can alter water levels to cover rocks and snags with water and trigger growth of new biofilms. </p>
<p>If we know how long it takes for biofilms to reach optimum quality, we can manage water levels to improve food value and benefit both biofilm grazers and the fish that eat them. </p>
<p>In our study, we sank wooden redgum blocks 20 centimetres under the surface of three rivers. Then we sampled the biofilm for 73 days, taking DNA to assess how the proportions of algae, cyanobacteria and fungi varied over time. </p>
<p>We developed a novel approach to assess food value, accounting for both quality of fatty acid profiles and their availability in space.</p>
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<img alt="" src="https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543181/original/file-20230817-29-v86h6h.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Redgum blocks give biofilm communities something to grow on.</span>
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<p>What did we find? Food value for animals peaked between 24 and 43 days after the blocks were submerged.</p>
<p>After 43 days, the food value of biofilms declined. Filamentous algae and cyanobacteria numbers increased as the biofilms aged, while green algae and diatoms abundance decreased. The amount of slimy-feeling natural polymers also increased over time, making our once-delicious biofilms even less nutritious.</p>
<p>So what does this mean? Water agencies are increasingly using environmental flows to support freshwater fish and animal populations. A widely used application for environmental water is to raise water levels in rivers and weirs to inundate new hard surfaces to grow new biofilms.</p>
<p>Now we know that after six weeks the food value of biofilms for animals declines – and that can help managers find the best ways of using environmental water to produce a biofilm bonanza for invertebrates and everything that eats them.</p>
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<strong>
Read more:
<a href="https://theconversation.com/unlocking-the-secrets-of-bacterial-biofilms-to-use-against-them-59148">Unlocking the secrets of bacterial biofilms – to use against them</a>
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<img src="https://counter.theconversation.com/content/211356/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul McInerney receives funding from the Murray Darling Basin Authority and the Commonwealth Environmental Water Office. </span></em></p>Slime gets a bad name in popular culture, but it’s food for invertebrates who become food for many other creatures.Paul McInerney, Senior Research Scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2041642023-09-10T13:04:13Z2023-09-10T13:04:13ZThe nose knows: How microbiomes and the smells they produce help shape behaviour in bugs, birds, beasts and humans<figure><img src="https://images.theconversation.com/files/547261/original/file-20230908-27-yeuep5.jpg?ixlib=rb-1.1.0&rect=612%2C68%2C4958%2C3759&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The microbiome functions as an 'invisible organ' but it often makes its presence known by emitting sounds and smells.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/the-nose-knows-how-microbiomes-and-the-smells-they-produce-help-shape-behaviour-in-bugs-birds-beasts-and-humans" width="100%" height="400"></iframe>
<p>Microbes are an integral part of most, if not all multi-cellular organisms. In fact, these organisms are the way they are because of the tiny partners they house within and on them. These microbes constitute the microbiome: an “invisible organ” weighing approximately <a href="https://doi.org/10.1007/978-981-10-7684-8">2.5 to three kilograms</a> in an adult human and much more in larger animals.</p>
<p>This unique body part was made visible with the advent of modern molecular imaging technologies. In my book <em><a href="https://www.routledge.com/Microbiomes-and-Their-Functions-Why-Organisms-Need-Microbes/Appanna/p/book/9780367749897">Microbiomes and their Functions</a></em>, I explore how it works in partnership with other visible organs and engages in a variety of physiological functions essential for the development and survival of the hosts. </p>
<p>Microbiomes have been part of all these organisms from the beginning, and have evolved in tandem with them, just as their visible organs have.</p>
<p>The digestive tract, with all its components, is a good example of how organs can be shaped by their microbial inhabitants. The digestive tract has markedly disparate features in a carnivore, an omnivore or a herbivore. Herbivores have the longest digestive tracts and <a href="https://opentextbc.ca/biology/chapter/15-1-digestive-systems/">carnivores have the shortest</a>.</p>
<h2>The microbiome</h2>
<p>The bulk of microbiome is found in the <a href="https://doi.org/10.1007/978-981-10-7684-8_2">digestive tract</a>, where it helps extract nutrients from our diet. The diverse microbes constituting the microbiome not only contribute to optimal digestion, but also help prime our immune system, and produce hormones and neurotransmitters (or their precursors) that have profound influence on our behaviours.</p>
<p>The information-laden molecules generated by the microbiome play a crucial role in the body’s <a href="https://doi.org/10.3389/fimmu.2020.00700">non-verbal communication</a>. These <a href="https://doi.org/10.1038/s41467-020-18871-1">microbiome-derived signals</a> can elicit a range of responses including hunger, satiety (feeling full), mood changes and social behaviour.</p>
<figure class="align-right ">
<img alt="Human silhouette showing the gut-brain connection" src="https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=796&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=796&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=796&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1000&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1000&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1000&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The information network between the gut microbiome and the brain is aided by the vagus nerve that connects these two organs.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>The information network between the gut microbiome and the brain is aided by the vagus nerve that <a href="https://routledge.pub/Microbiomes-and-Their-Functions">connects these two organs</a>.</p>
<p>Microbes like Lactobacillus and Bifidobacterium residing in the gut secrete neurotransmitters known to influence human behaviour <a href="https://doi.org/10.3390/cimb44040096">such as GABA</a> (gamma-aminobutyric acid), acetylcholine, norepinephrine, oxytocin and indole metabolites. Indole derivatives are obtained when gut microbes metabolize the essential amino-acid, tryptophan.</p>
<p>For instance, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449495">neurotransmitter dopamine</a> is considered a “feel good” hormone and is often associated with positive emotions. However, low levels of this molecule may contribute to anxiety. On the other hand, indoles are linked to satiety, resulting in a tendency to eat less, and are associated with weight loss.</p>
<h2>Smelly signals</h2>
<p>Despite its invisible nature, the microbiome often makes its presence known by emitting sounds and smells. The latter can be powerful signals that can influence behaviour.</p>
<p>These smelly signals can, at a distance or at a close range, prompt happiness, enthusiasm, anxiety, attraction, fear or <a href="https://doi.org/10.1007/978-981-10-7684-8">aggression</a>. The microbially-concocted odours are a very important tool in the communication arsenal that most organisms — including humans — rely on to send or receive non-verbal messages.</p>
<p>The human skin is home to a diverse range of microorganisms known to contribute to different odours. Bacteria like Staphylococcus and Corynebacterium lodge in the warm and moist underarm region of the skin where the apocrine glands, a source of chemicals, abound. The resident bacteria use these chemical nutrients to shape <a href="https://asm.org/Articles/2021/December/Microbial-Origins-of-Body-Odor">body odour</a>.</p>
<p>These apocrine glands generally produce odourless compounds. It is microbes that fashion those compounds into smell signatures characteristic of an individual. These odoriferous signals can serve to attract or repel people and modify social behaviours. For instance, the presence of select bacteria is known to process non-smelly steroids into compounds with a characteristic urine odour, not conducive to making friends. </p>
<h2>Chemical signals in animals, birds, plants, fungi</h2>
<p>In other mammals, odoriferous compounds like trimethylamine or pentanoic acid entice mates, while in animals endowed with a scent pouch, they lure prey, defend or mark territories. Some of the <a href="https://doi.org/10.3389/fevo.2017.00143">pungent chemicals</a> are notoriously reputed to keep <a href="https://www.washingtonpost.com/lifestyle/kidspost/whats-that-smell-for-some-animals-their-stink-helps-keep-them-alive/2018/08/13/9058fc62-9678-11e8-810c-5fa705927d54_story.html">predators at bay</a>. </p>
<p>Birds have a special gland that hosts a diverse microbial population, which generates scent-releasing chemicals. These easily transmittable signals are aimed at repelling predators, attracting mates, recognizing kin, promoting parental care and <a href="https://www.nytimes.com/2019/11/10/science/birds-smell-bacteria.html">identifying proprietary nests</a>.</p>
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<img alt="A man's hand holding a small shovel with a truffle on it, patting his truffle-hunting dog with his other hand" src="https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Truffles — the highly sought-after edible fungus — recruit select microbes to generate aromatic alcohols that lure small mammals to dig them up, which promotes the dispersal of the truffle’s spores.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>These smelly marks are also key to maintaining the social order of numerous insects. <a href="https://doi.org/10.1186/s40168-018-0588-z">These scents</a> can not only help camouflage the hosts, but can also convert loners to crowd-lovers. For instance, it is a scent that cajoles the solitary <a href="https://doi.org/10.3390/insects11100655">locust</a> into a gregarious lifestyle during the feeding season and triggers an insatiable appetite for vegetation.</p>
<p>Some fungi are known to enlist the fragrance of vapour-like chemicals to assemble their microbiome, which in turn helps the host perform a variety of essential physiological functions.</p>
<p>Truffles — the highly sought-after edible fungus — are renowned for their distinctive smell, but they may be dependent on the microbiome to produce this sweet fragrance. In fact, <a href="https://doi.org/10.1128/aem.01098-15">truffles recruit select microbes</a> to generate aromatic alcohols that lure small mammals to dig them up, which promotes the dispersal of the truffle’s spores.</p>
<p>Plants and algae are also dependent on microbe-derived odour prompts to assist them to survive, and even die and be scavenged. Plants depend on these smell signatures to communicate dangers lurking in their environment and even to fend off insects, birds or <a href="https://doi.org/10.3389/fmicb.2021.772420">other predators</a>.</p>
<p>When some algae bloom beyond control due to environmental conditions, they plot their own demise with the <a href="https://doi.org/10.1201/9781003166481">assistance of microbes</a>. Some of these microbes not only help the algae die, but are also responsible for producing distinctive odours that are detected and decoded as food by birds and fish. The result is a clean-up of the dead algae by feasting birds and fish.</p>
<p>The microbiome and its signature smells are crucial for most organisms, whether human, insect or plant. The silent signals sent by the microbiome are essential communications that influence behaviour, and have evolved to help the host survive and thrive.</p><img src="https://counter.theconversation.com/content/204164/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vasu Appanna receives / has received funding from NATO, NSERC, NOHFC and FEDNOR</span></em></p>The microbiome and its signature smells are crucial for most organisms, whether human, insect or plant. The silent signals sent by the microbiome are essential communications that influence behaviour.Vasu Appanna, Professor, Biochemistry, Laurentian UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2120492023-08-24T14:55:46Z2023-08-24T14:55:46ZHow do coral reefs thrive in parts of the ocean that are low in nutrients? By eating their algal companions<figure><img src="https://images.theconversation.com/files/544330/original/file-20230823-36239-dk7lmg.jpg?ixlib=rb-1.1.0&rect=31%2C25%2C4233%2C3088&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Coral reefs are hotspots of productivity in otherwise nutrient-poor parts of our oceans.</span> <span class="attribution"><span class="source">Joerg Wiedenmann & Cecilia D'Angelo/University of Southampton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Coral reefs thrive in parts of the world’s oceans that are low in nutrients. This mystery has puzzled scientists for centuries and has become known as the <a href="https://www.nhm.ac.uk/discover/charles-darwin-coral-conundrum.html">“Darwin paradox of coral reefs”</a>.</p>
<p>Our <a href="https://doi.org/10.1038/s41586-023-06442-5">new study</a> adds the missing piece of the puzzle. We found that many species of coral <a href="https://youtu.be/DsQO_1sB5is">cultivate and feed on</a> the microscopic algae that live inside their cells. This vegetarian diet allows the corals to tap into a large pool of nutrients that was previously considered unavailable to them.</p>
<p><a href="https://www.britannica.com/animal/coral">Stony corals</a> are soft-bodied animals made up of many individual polyps that live together as a colony. They secrete limestone skeletons that form the foundation of reefs. The coral polyps acquire nutritious compounds rich in nitrogen and phosphorus by catching prey like <a href="https://www.britannica.com/science/zooplankton">zooplankton</a> with their tentacles. </p>
<p>Many coral animals are also dependent on a symbiosis – a mutually beneficial relationship – with the microscopic algae that live inside their cells. These photosynthetic algae produce large amounts of carbon-rich compounds, such as sugars, and transfer them to the host coral to generate energy. However, as most photosynthetic products are deficient in nitrogen and phosphorous, they cannot sustain the growth of the animals. </p>
<p>Our findings suggest that, while coral animals may survive brief periods of starvation by feeding on their symbionts, some coral reefs could face the risk of prolonged nutrient deficiency due to global warming. This is concerning. Coral reefs are <a href="https://www.unep.org/explore-topics/oceans-seas/what-we-do/protecting-coral-reefs/why-protecting-coral-reefs-matters">important underwater ecosystems</a> that provide a home and feeding ground for countless organisms, sustaining around 25% of the world’s ocean biodiversity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Symbiont algae from a reef coral viewed under a microscope." src="https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=535&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=535&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=535&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=672&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=672&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544337/original/file-20230823-21-dat40a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=672&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Symbiont algae from a reef coral viewed under a microscope.</span>
<span class="attribution"><span class="source">J. Wiedenmann & C. D’Angelo/University of Southampton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Vegetarian diet</h2>
<p>The symbiotic algae living within the corals are very efficient at taking up dissolved inorganic nutrients, like nitrate and phosphate, from the surrounding seawater. Even in nutrient-poor areas of the ocean, these compounds are present in considerable amounts as excretion products of organisms, <a href="https://www.nature.com/articles/35099547">such as sponges</a>, that live close by. Ocean currents can also <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/ecog.04097">transport these nutrients</a> to reefs. </p>
<p>The coral host, on the other hand, cannot absorb or use nitrate and phosphate directly. But, through a series of long-term laboratory experiments, we demonstrated that corals actually digest some of their symbiont population to access the nitrogen and phosphorus that these algae absorb from the water. </p>
<p>To provide evidence that the nutrients accumulated by the growing coral tissue originated from the symbionts, we supplied the corals with a chemical form of nitrogen that can only be absorbed from the water by the symbionts, not by the coral host.</p>
<p>This nutrient compound was marked by a technique called <a href="https://www.sciencedirect.com/science/article/pii/S0039914018309226">isotopic labelling</a>, which uses nitrogen atoms that are heavier than normal. These “heavy” isotopes allowed us to track the movement of nitrogen between the partners of the symbiosis by ultrasensitive detection methods. </p>
<p>With this method, we could unambiguously demonstrate that the nitrogen atoms that sustained the growth of the coral tissue were derived from the dissolved inorganic nutrients that were fed to their symbiont algae.</p>
<p>Our data suggest that most species of symbiotic corals can supplement their nutrition through such a vegetarian diet.</p>
<h2>From the laboratory to the ocean</h2>
<p>Together with our <a href="https://doi.org/10.1038/s41586-023-06442-5">colleagues</a>, we also analysed corals growing around remote islands in the Indian Ocean, some with seabirds on them and some without. Our results show that corals have the potential to farm and feed on their symbiont algae in the wild too. </p>
<p>The reefs around some of these islands are supplied with substantial amounts of nutrients that come from “guano” – the excrement of seabirds nesting on the islands. On some of the other islands, seabird colonies <a href="https://www.nature.com/articles/s41586-018-0202-3">have been decimated</a> by invasive rats. The reefs surrounding these islands receive fewer nutrients. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/invasive-rats-are-changing-fish-behaviour-on-coral-reefs-new-study-197215">Invasive rats are changing fish behaviour on coral reefs – new study</a>
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<p>We measured the growth of <a href="https://www.nationalgeographic.com/animals/invertebrates/facts/staghorn-coral">staghorn coral</a> colonies both around islands with and without dense seabird populations and found that growth was more than twice as fast on reefs that were supplied with seabird nutrients. About half of the nitrogen molecules in the tissue of the coral animals from islands with seabirds could be traced back to uptake by the symbiont algae.</p>
<figure class="align-center ">
<img alt="A group of seabirds above a tropical beach." src="https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544331/original/file-20230823-7859-833k3d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Reefs around islands in the Indian Ocean receive additional nutrients if the islands are inhabited by seabirds.</span>
<span class="attribution"><span class="source">N. Graham/Lancaster University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Global warming could complicate matters</h2>
<p>In the future, some coral reefs could face a <a href="https://www.nature.com/articles/ncomms10581">decrease in nutrient availability</a> due to global warming. Research suggests that warming surface waters are <a href="https://www.nature.com/articles/nature05317">less likely to</a> receive nutrients from deeper water layers. The reduced water productivity could result in fewer nutrients for their symbionts and subsequently less food for the coral animals. </p>
<p>Our study indicates that some coral reefs might become vulnerable to starvation as ocean temperatures warm. When we moved corals from water with ample nutrients to water with fewer nutrients, they continued to eat their symbiont algae. This behaviour allowed them to sustain their growth for a few weeks, even in the absence of feeding.</p>
<p>But once they had exhausted their population of symbiotic algae, the coral underwent bleaching (referring to the white appearance of the corals with low symbiont numbers in their tissue), stopped growing – and in some cases eventually died.</p>
<figure class="align-center ">
<img alt="Two photos comparing coral growth in different environments." src="https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=526&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=526&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=526&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=661&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=661&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544334/original/file-20230823-15-yzs1p7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=661&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Corals grew fast in nutrient-rich water despite the absence of food (top). Corals in nutrient-depleted water stopped growing and showed a bleached appearance (bottom).</span>
<span class="attribution"><span class="source">L. Mardones-Velozo, C. D’Angelo & J. Wiedenmann, University of Southampton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Our findings reveal that corals can not only acquire nitrogen and phosphorus by feeding on prey as other animals do. But, by eating parts of their symbiont stock, they can also efficiently tap into the pool of dissolved inorganic nitrogen and phosphorus that is otherwise only accessible to plants.</p>
<p>Through this process, symbiotic corals gain an advantage over other animals in environments that are low in nutrients, explaining their prominent role in the formation of reefs in nutrient-poor water. </p>
<p>However, increasingly severe nutrient depletion will add a further threat to some coral reefs already experiencing bleaching caused by heat stress.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 20,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/212049/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jörg Wiedenmann receives funding from Natural Environment Research Council (NERC) (NE/T001364/1).
Paul Wilson and Peter Franklin (University of Southampton) and Nick Graham (Lancaster University) contributed to the press release that fomed the basis of this article.</span></em></p><p class="fine-print"><em><span>Cecilia D'Angelo receives funding from Natural Environment Research Council NERC (NE/T001364/1). </span></em></p>Reef corals grow vigorously in nutrient poor water – new research has found out why.Jörg Wiedenmann, Professor of Biological Oceanography & Head of the Coral Reef Laboratory, University of SouthamptonCecilia D'Angelo, Associate Professor, Coral Reef Laboratory, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2071522023-08-06T19:59:54Z2023-08-06T19:59:54ZHow algae conquered the world – and other epic stories hidden in the rocks of the Flinders Ranges<figure><img src="https://images.theconversation.com/files/539439/original/file-20230726-21-y5r0d0.JPG?ixlib=rb-1.1.0&rect=32%2C44%2C4249%2C2798&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Alan Collins</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Earth was not always so hospitable. Evidence of how it came to be so beautiful and nurturing is locked in the rocks of South Australia’s Flinders Ranges – a site now vying for <a href="https://www.environment.sa.gov.au/topics/flinders-ranges-world-heritage-nomination">World Heritage listing</a>.</p>
<p>Our <a href="https://www.cambridge.org/core/journals/geological-magazine/article/geochronology-and-formal-stratigraphy-of-the-sturtian-glaciation-in-the-adelaide-superbasin/1D635EDFDB155C19FF8481D178F86AC7">new</a> <a href="https://oap.unige.ch/journals/sdk/article/view/1083">research</a> seeks to better understand this near billion-year-old story. We discovered immense planetary upheaval recorded in the ranges.</p>
<p>In two related research projects, we’ve mapped how the continent that later became Australia responded to the most extreme climate change known in Earth’s history. We then dated this event. </p>
<p>The changes gave rise to <a href="https://www.anu.edu.au/news/all-news/anu-led-study-solves-mystery-of-how-first-animals-appeared-on-earth">algae</a>. Their legacy is the oxygen we breathe and the <a href="https://theconversation.com/ancient-sponges-or-just-algae-new-research-overturns-chemical-evidence-for-the-earliest-animals-150635">evolution of the first animals</a> more than 500 million years ago. The soft bodies of these animals have been exceptionally preserved at the new <a href="https://www.parks.sa.gov.au/parks/nilpena-ediacara-national-park">Nilpena-Ediacara National Park</a>, which opened in April 2023. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1603543240816627713"}"></div></p>
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Read more:
<a href="https://theconversation.com/friday-essay-histories-written-in-the-land-a-journey-through-adnyamathanha-yarta-124001">Friday essay: histories written in the land - a journey through Adnyamathanha Yarta</a>
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<h2>A superbasin on the shores of the Pacific</h2>
<p>The rocks of the Flinders Ranges formed at the same time as the Pacific Ocean basin. The plate tectonic “<a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">dance of the continents</a>” tore North America away from Australia 800 million years ago. This created a valley that became an ocean where sand and mud was deposited. </p>
<p>Geologists call this the <a href="https://www.sciencedirect.com/science/article/pii/S0301926820300875">Adelaide Superbasin</a>. “Super” because it is huge, and “basin” because it formed a depression where sediment could accumulate. </p>
<p>The superbasin stretches from Kangaroo Island in the south, to north of the Flinders Ranges and from Coober Pedy in the west to the Barrier Ranges of New South Wales in the east.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of South Australia marking out the area of the Adelaide Superbasin" src="https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=565&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=565&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=565&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=710&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=710&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539901/original/file-20230728-17-434fnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=710&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the Adelaide Superbasin. The national parks highlighted form part of the World Heritage nomination: Ikara-Flinders Ranges, Vulkathanana-Gammon Ranges and Nilpena Ediacara national parks.</span>
<span class="attribution"><span class="source">Alan Collins, with Google Earth basemap</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>At special places such as <a href="https://www.arkaroola.com.au/">Arkaroola</a> and the national parks of <a href="https://www.parks.sa.gov.au/parks/vulkathunha-gammon-ranges-national-park">Vulkathunha-Gammon Ranges</a> and <a href="https://www.parks.sa.gov.au/parks/ikara-flinders-ranges-national-park">Ikara-Flinders</a>, rocks of the Adelaide Superbasin tell us how our planet came to be the way it is today. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-map-that-fills-a-500-million-year-gap-in-earths-history-79838">A map that fills a 500-million year gap in Earth's history</a>
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<hr>
<h2>Land of fire and ice</h2>
<p>Until about 800 million years ago, Earth was an oxygen-poor but stable planet. So stable, in fact, this time has been nicknamed the “<a href="https://theconversation.com/earths-boring-billion-years-of-stagnant-stinking-oceans-might-actually-have-been-rather-dynamic-120134">Boring Billion</a>”. </p>
<p>That all changed 716 million years ago. The planet plunged into an 80-million-year Ice Age, the likes of which has never been seen again. It’s known as the <a href="https://stratigraphy.org/chart">Cryogenian</a> Period. </p>
<p>The Cryogenian contains a least two global glaciations when the planet became covered in ice - an occurrence earth scientists refer to as “Snowball Earth”. What caused this incredible cooling is still a mystery. But many researchers think it relates to <a href="https://theconversation.com/ancient-volcanic-eruptions-disrupted-earths-thermostat-creating-a-snowball-planet-82215">huge volcanic eruptions</a> that directly preceded the icy conditions. The heavily worn remains of these volcanoes have <a href="https://www.science.org/content/article/massive-lava-outburst-may-have-led-snowball-earth">recently been discovered</a> in Arctic Canada and Alaska.</p>
<p>We know lava from volcanoes reacts with CO₂, dragging it out of the atmosphere. Scientists believe this reversed the pre-historic greenhouse effect and the <a href="https://www.science.org/content/article/massive-lava-outburst-may-have-led-snowball-earth">planet cooled</a>. </p>
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<strong>
Read more:
<a href="https://theconversation.com/ancient-volcanic-eruptions-disrupted-earths-thermostat-creating-a-snowball-planet-82215">Ancient volcanic eruptions disrupted Earth's thermostat, creating a 'Snowball' planet</a>
</strong>
</em>
</p>
<hr>
<h2>Part One: Picturing the world before the first animals</h2>
<p>The first part of our <a href="https://doi.org/10.57035/journals/sdk.2023.e11.1083">new research</a> reconstructs the shores of the balmy Pacific as this climate shock hit, causing vast ice sheets to lumber north and smother the region for millions of years. </p>
<p>The glaciers ploughed through hills and valleys, planing off the country and leaving behind vast swathes of boulder clay that now forms rocks over much of the Flinders Ranges.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A coloured graphic showing the correlations between rock sections from across the Flinders Ranges" src="https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539907/original/file-20230728-29-434fnd.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Correlation of rock sections across the northern Flinders Ranges. Blue represents rocks deposited during and after the Sturt glaciation. These sequences overlie rocks deposited in warm, tropical conditions (pink).</span>
<span class="attribution"><a class="source" href="https://oap.unige.ch/journals/sdk/article/view/1083">Georgina Virgo, from Virgo et al. (2023) Sedimentologika</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our research analysed unusual magnesium-rich sedimentary rocks in part formed by microscopic bacteria. Hundreds of millions of years later, small variations in the concentration of critical elements are still preserved. We used these variations to build a picture of highly saline shallow seas rich in bacterial life, but devoid of much else. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of ancient rock in the northern Flinders Ranges, with a pink pen laid on top to show the scale." src="https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539910/original/file-20230728-3774-tg6vet.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This ancient rock called diamictites was deposited by the Sturtian glaciers in the northern Flinders Ranges.</span>
<span class="attribution"><span class="source">Georgina Virgo</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Part Two: Dating Snowball Earth</h2>
<p>Dating sedimentary rocks is challenging. The grains of sand and pebbles that make up the rock formed elsewhere. They were carried by wind or water to the beach, or river, where they were deposited. Then, gradually, new rock formed. </p>
<p>Using established methods we can date one of the minerals in the sand (zircon). This <a href="https://en.wikipedia.org/wiki/Uranium%E2%80%93lead_dating">uranium–lead method</a> gives us the oldest possible age for sedimentary rock. That’s a reliable maximum age, but the true age of the rock could be much younger.</p>
<p>In the second part of our <a href="https://doi.org/10.1017/S0016756823000390">research</a> we combined this established method with a new technique called “<a href="https://doi.org/10.1130/G49187.1">in-situ rubidium–strontium dating</a>”. This enabled us to more accurately date the Snowball Earth rocks in the Flinders Ranges called the Sturt Formation.</p>
<p>The new technique attempts to directly date the “glue” that holds the grains of sedimentary rocks together. So we’re using a laser to date minerals that form as the sediment turns to rock. Some of these “authigenic” minerals (minerals that form “in place”) contain tiny amounts of radioactive rubidium. Over time, rubidium changes to strontium by radioactive decay. </p>
<p>Our study dates mudrock deposited within the glaciation. It is the first study to directly date sedimentary rocks that formed during the Snowball Earth event. This mudrock (a part of the Sturt Formation) formed around 684 million years ago. </p>
<p>Our “detrital zircon” method also gave us maximum ages of about 698 million years for a boulder clay below the mudrock, and about 663 million years from a boulder clay above the mudrock. These dates fit with estimates from elsewhere on the globe, suggesting the icy time likely lasted 50 million years.</p>
<p>Put together, the results of these two projects suggest the “Sturtian” glaciation took place between 716 and 663 million years ago and may have been more dynamic than previously thought. It’s likely there were at least two ice-advance and ice-retreat events, or two separate glacial times. So the planet experienced more of a cold period rather than a completely frigid snowball. </p>
<h2>The rise of the algae</h2>
<p>These two research projects using rocks within the proposed World Heritage area, along with work from many other researchers, develops a picture of the world that led to the evolution of the first animals. The geological processes and their timing helps us understand how the Earth system came to be.</p>
<p>The frozen world of the Cryogenian stressed the microbial life that dominated the oceans way back then. Glaciers ground rock to powder and this powder turned the oceans of the day to a nutrient soup. </p>
<p>So when warmer times came, a previously minor player in the biosphere bloomed. This newcomer was <a href="https://www.anu.edu.au/news/all-news/anu-led-study-solves-mystery-of-how-first-animals-appeared-on-earth">algae</a>, life with cells containing a nucleus. Essentially, seaweed.</p>
<p>They were larger than the life that existed before and better at photosynthesising. They pumped their oxygen waste into the oceans and atmosphere, inadvertently providing the fuel for microbes to combine to form more complex multicellular life forms (metazoans) and ultimately, the first animals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of the Flinders Ranges with a tree in the foreground and hills in the background, layers of ancient rock are visible" src="https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539438/original/file-20230726-15-yb1l39.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The hills in the background contain layers of 800 million year old rocks from the northern part of the ‘Adelaide Superbasin’ in the Flinders Ranges.</span>
<span class="attribution"><span class="source">Alan Collins</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A place of true world heritage</h2>
<p>The rocks of the Flinders Ranges preserve so many stories, from the <a href="https://theconversation.com/friday-essay-histories-written-in-the-land-a-journey-through-adnyamathanha-yarta-124001">Dreamtime-formed shapes of the ranges</a>, to the scars of the early mining history. </p>
<p>Our research into these rocks links the interdependence of Earth systems. Here we find stories about how plate tectonics and volcanoes control the climate, how the climate helps feed life with nutrients and how the resulting life changes the chemistry of the ocean and atmosphere, feeding back into powering new forms of life.</p>
<p>The stories locked in the hills of the Flinders Ranges undoubtedly give the region a heritage value to the world. We eagerly await news of world heritage listing, which is <a href="https://www.theguardian.com/australia-news/2022/aug/21/south-australias-flinders-ranges-nominated-for-unesco-world-heritage-status">not expected until 2025</a> at the earliest.</p><img src="https://counter.theconversation.com/content/207152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alan Collins receives funding from the Australian Research Council, MinEx CRC, BHP, Santos, Empire Energy, Teck Resources and the NT, SA and WA Governments. He is affiliated with the Geological Society of Australia and the Australian Institute of Geoscientists. </span></em></p><p class="fine-print"><em><span>Georgina Virgo received funding from the Geological Survey of South Australia as part of her PhD project at The University of Adelaide. </span></em></p><p class="fine-print"><em><span>Jarred Lloyd receives funding from the Australian Research Council through the Australian Critical Minerals Research Centre at the University of Adelaide, and his research position is also supported by the SA Government. He is affiliated with the Geological Society of Australia. </span></em></p>New research dating and reading the rocks of the Flinders Ranges in South Australia reveals a fascinating story about how complex life emerged on our planet.Alan Collins, Professor of Geology, University of AdelaideGeorgina Virgo, Research assistant, University of AdelaideJarred Lloyd, Postdoctoral research fellow, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2077852023-06-23T15:51:06Z2023-06-23T15:51:06ZThe melting Arctic is a crime scene. The microbes I study have long warned us of this catastrophe – but they are also driving it<p>The Arctic’s climate is warming at least four times faster than the global average, causing irrevocable changes to this vast <a href="https://news.sky.com/story/dramatic-changes-to-polar-ice-caps-revealed-on-new-map-of-arctic-and-antarctica-12898550">landscape</a> and precarious <a href="https://www.nwf.org/Educational-Resources/Wildlife-Guide/Wild-Places/Arctic#:%7E:text=The%20Arctic%20is%20a%20unique,in%20the%20summer%20to%20breed.">ecosystem</a> – from the anticipated <a href="https://earth.org/polar-bears-to-become-extinct-by-2100/">extinction of polar bears</a> to the <a href="https://www.scientificamerican.com/article/as-arctic-sea-ice-melts-killer-whales-are-moving-in/#:%7E:text=Killer%20whales%20often%20feed%20on,navigate%20through%20the%20icy%20waters.">appearance of killer whales</a> in ever-greater numbers. A new <a href="https://www.nature.com/articles/s41467-023-38511-8">study</a> suggests the Arctic Ocean could be ice-free in summer <a href="https://theconversation.com/arctic-ocean-could-be-ice-free-in-summer-by-2030s-say-scientists-this-would-have-global-damaging-and-dangerous-consequences-206974">as soon as the 2030s</a> – around a decade earlier than previously predicted.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Arctic sea ice changes" src="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=700&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=700&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=700&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=879&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=879&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532508/original/file-20230618-17-lemk5e.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=879&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A new Arctic sea ice map compares the 30-year average with recent ten-year averages.</span>
<span class="attribution"><a class="source" href="https://www.bas.ac.uk/media-post/new-map-of-polar-regions-updated-to-reflect-ice-loss-name-changes-and-new-data/">British Antarctic Survey</a></span>
</figcaption>
</figure>
<p>But to properly understand the pace and force of what’s to come, we should instead focus on organisms too small to be seen with the naked eye. These single-celled microbes are both the watchkeepers and arch-agitators of the Arctic’s demise.</p>
<p>Scientists like me who study them have become forensic pathologists, processing crime scenes in our Arctic field sites. We don the same white anti-contamination suits, photograph each sampling site, and bag our samples for DNA analysis. In some areas, red-coloured microbes even create an effect known as “blood snow”.</p>
<p>In this complex criminal investigation, however, the invisible witnesses are also responsible for the damage being done. Microbes testify to the vulnerability of their Arctic habitats to the changes that humans have caused. But they also create powerful climate feedback loops that are doing ever-more damage both to the Arctic, and the planet as a whole.</p>
<h2>Zipping headlong into icy oblivion</h2>
<p>My first visit to the Arctic was also nearly my last. As a PhD student in my early 20s in 2006, I had set out with colleagues to sample microbes growing on a glacier in the Norwegian archipelago of <a href="https://www.theguardian.com/environment/2023/may/13/svalbard-the-arctic-islands-where-we-can-see-the-future-of-global-heating">Svalbard</a> – the planet’s northernmost year-round settlement, about 760 miles from the North Pole.</p>
<p>Our treacherous commute took us high above the glacier, traversing an icy scree slope to approach its flank before crossing a river at the ice’s margin. It was a route we had navigated recently – yet this day I mis-stepped. Time slowed as I slid towards the stream swollen with ice melt, my axe bouncing uselessly off the glassy ice. I was zipping headlong into icy oblivion.</p>
<p>In that near-death calm, two things bothered me. The water would carry me deep into the glacier, so it would be decades before my remains were returned to my family. And the ear-worm of that field season meant I would die to the theme tune to Indiana Jones.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>This article is part of Conversation Insights</em></strong>
<br><em>The Insights team generates <a href="https://theconversation.com/uk/topics/insights-series-71218">long-form journalism</a> derived from interdisciplinary research. The team is working with academics from different backgrounds who have been engaged in projects aimed at tackling societal and scientific challenges.</em></p>
<hr>
<p>Thankfully, the scree slowed my slide – I lived and learned, quickly, that dead scientists don’t get to write up their papers. And I’m still learning about the tiny organisms that populate every habitat there: from seawater in the Arctic Ocean to ice crystals buried deep in the <a href="https://en.wikipedia.org/wiki/Greenland_ice_sheet">Greenland ice sheet</a>.</p>
<p>These micro-managers of all manner of planetary processes are acutely sensitive to the temperatures of their habitats. The slightest change above freezing can transform an Arctic landscape from a frozen waste devoid of liquid water to one where microbes get busy reproducing in nutrient-rich water, transforming themselves in ways that <a href="https://www.nature.com/articles/ismej2010108">further amplify</a> the effects of climate warming.</p>
<p>The Svalbard region is now warming seven times faster than the global average. While much of the world continues its efforts to limit global warming to 1.5°C above pre-industrial levels, in the Arctic, that battle was lost long ago.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0VOGGdeB8eI?wmode=transparent&start=17" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Joseph Cook’s film on the microbes that inhabit the Greenland ice sheet.</span></figcaption>
</figure>
<h2>Decades ahead of us all</h2>
<p>It’s 2011, and <a href="http://www.earth.s.chiba-u.ac.jp/english/education/education02/staff16.html">Nozomu Takeuchi</a> is visiting Svalbard from Japan. It has been a difficult year back home, following the earthquake, tsunami and Fukushima nuclear incident, but Nozomu – a glacier ecologist and professor at Chiba University – is unrelenting in his quest to measure the effects of climate change. </p>
<p>Just hours after he stepped off a plane in the August midnight sun at Longyearbyen airport, we are marching up the nearest glacier. Above us, snow-capped mountain sides loom out of the swirling mist.</p>
<p>Since the 1990s, Nozomu has been collecting samples and measurements from glaciers all over the world. When we reach our goal near the snowline, he opens his rucksack to reveal a bento box full of sampling kit – stainless steel scoops, test tubes, sample bags, all arranged for efficiency. As he scurries around with practised efficiency, I think of offering help but fear I would only slow him down.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist takes a reading in snowy Arctic landscape" src="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532612/original/file-20230619-27-w8e0xr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nozomu Takeuchi measuring the biological darkening of a Svalbard glacier in 2011.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In truth, Nozomu is decades ahead of us all. Years ago, he made the link between the future of life and the death of ice, and these melting Svalbard glaciers are adding yet more points to his graphs.</p>
<p>Just as we apply oodles of factor 50 to protect ourselves from the Sun, so the billions of microbes sandwiched between the sky and surface of the glacier protect themselves by accumulating sunscreen-like pigments. And if enough of these pigments rest in one place under the Sun, this area of “biological darkening” absorbs the heat of the Sun much more effectively than reflective white snow and ice – so it melts faster.</p>
<p>Nozomu scoops up some of the so-called blood snow, heavily laden with algae. Under the microscope, their cells are indeed reminiscent of red blood cells. But rather than haemoglobin, these cells are laden with carotenoids – pigments also found in vegetables that <a href="https://academic.oup.com/femsec/article/94/3/fiy007/4810544?login=false">protect the algae from overheating</a>. Other patches of the glacier are verdant green, rich in algae that are busy photosynthesising light into chemical energy in this 24-hour daylight world.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man in icy landscape holding scientific sample" src="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532611/original/file-20230619-29-l44kho.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author with a sample of ‘blood snow’, collected from a glacier surface.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Further down the glacier, the professor crushes some “dirty” ice into a bag. A different kind of algae lives here that, depending on your point-of-view, is either black, brown or purple (perhaps it depends on the tint of your sunglasses). The <a href="https://www.researchgate.net/figure/Chemical-structure-of-compound-3-purpurogallin-carboxylic-acid-6-O-b-d-glucopyranoside_fig2_51806131#:%7E:text=A%20gallotannin%20derivative%20(galloylglucopyranose%2C%20i.e.,et%20al.%2C%202012b)%20.">pigment</a> created is like the compounds that colour tea, and the algae keep it in layers like parasols above the photosynthetic factories within their cells – ensuring they have just enough sunlight to photosynthesise, but not enough to burn.</p>
<p>Open Google Earth and as you zoom in on the Arctic, you may spot the large dark stripe that scars the western margin of the <a href="https://en.wikipedia.org/wiki/Greenland_ice_sheet">Greenland ice sheet</a>. This is the “dark zone”, but it’s not caused by dark <a href="https://www.nature.com/articles/s41467-020-20627-w">dust</a> or soot. It’s alive, <a href="https://www.nature.com/articles/ismej2012107">laden with algae</a> – and it has been darkening, and growing, as Greenland warms.</p>
<p>Between 2000 and 2014, the <a href="https://www.frontiersin.org/articles/10.3389/feart.2016.00043/full">dark zone’s area grew by 14%</a>. At 279,075 km² in 2012, it was already more than twice the <a href="https://www.britannica.com/summary/England#:%7E:text=Area%3A%2050%2C301%20sq%20mi%20(130%2C278,even%20with%20the%20entire%20kingdom.).%20This%20had%20a%20powerful%20impact%20on%20the%20rate%20of%20ice%20melt%20--%20areas%20blooming%20with%20algae%20%5Bmelt%20nearly%202cm%20more%20each%20day%5D(https://www.pnas.org/doi/abs/10.1073/pnas.1918412117">size of England</a> than bare ice.</p>
<p>Next morning, I am woken by the smell of chemicals, having slept beneath a coffee table. Nozomu is busy processing his samples: bags of melting ice pinned to a clothesline by bulldog clips. They resemble bunting around the crowded room, but this is no time for celebration. The tint of each bag adds a measurement which quantifies the link between these algae, their pigments, and the death of their icy home.</p>
<h2>The case becomes urgent</h2>
<p>By the summer of 2014, glaciologists all over the world have started to listen to the warnings of pioneering ecologists such as Nozomu. The glaciers are dying even as life blossoms on their darkening surfaces. The case has become urgent.</p>
<p>I am in a helicopter, flying with colleagues to a camp in the dark zone on the Greenland ice sheet – the largest mass of glacial ice in the northern hemisphere. Covering 1.7 million km², its ice holds the equivalent of the water required to raise global sea levels by 7.7 metres.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A landscape of dark ice intertwined with blue rivers of meltwater." src="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532620/original/file-20230619-23-shc4a3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A highly darkened surface of the Greenland ice sheet, rich in algae and incised with rivers of meltwater.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As we warm our climate, the rate of water flowing from this reservoir increases, with each degree Celsius added to global temperatures opening the drainage valve even wider. Feedback processes such as biological darkening have the potential to multiply the number of drainage valves that are open, hastening dramatically the rate at which sea levels rise.</p>
<p>To monitor this effect, every day <a href="https://www.gla.ac.uk/schools/ges/staff/karencameron/">Karen Cameron</a>, the leader of our camp this summer, walks to undisturbed patches of ice carrying a £100,000 backpack which contains a spectrometer to measure the darkness of the ice, capturing how it absorbs the solar energy that causes melting. The glaciologists are desperate for ground truth, and their models need data.</p>
<p>Up to this point, none of their predictions of how the Greenland ice sheet would respond to our warming climate have included biological darkening. Even if the effect were modest, it could still topple the ice sheet from a predictable, straightline response to climate warming.</p>
<p>All the time we are in Greenland, the only lifeforms we encounter are the flies that hatch from the fresh fruit and peppers in our food rations. These and the few types of glacier algae and several hundred kinds of bacteria that are biologically darkening the ice: a living scum scarring the surface of the ice sheet.</p>
<p>My work focuses on how these tiny organisms adapt to their icy habitat, but the implications of their behaviour are now of global concern. A <a href="https://screenworks.org.uk/archive/baftss-practice-research-award-2017/timeline">filmmaker</a> at the camp is weaving a thread between the ice melt in Greenland and its consequences for people living in coastal communities all over the world – from villages near my home on the <a href="https://www.theguardian.com/environment/2019/may/18/this-is-a-wake-up-call-the-villagers-who-could-be-britains-first-climate-refugees">west coast of Wales</a>, to huge metropolises like Manhattan, Amsterdam and Mumbai, and even entire low-lying island nations in the Pacific.</p>
<p>As smaller glaciers fade, and the larger ice sheets of Greenland and Antarctica start to respond with full force to our warming climate, it is these communities, capitals and countries that will bear the brunt of the flooding, inundation and erosion that comes with rising sea levels.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two scientists inspecting an ice corer device dripping with meltwater." src="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532622/original/file-20230619-28-oh4l8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author (left) and Joseph Cook high on the Greenland ice sheet, meltwater dripping from their ice corer.</span>
<span class="attribution"><span class="source">Sara Penrhyn Jones</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Before heading home, our helicopter takes us on a detour, high over the ice sheet. We fly over the brown-black-purple algae to brighter, higher elevations where the palette shrinks to the blue and white of water and ice, then snow and sky. Greenland makes its own weather and, in these higher elevations, we expect the ice to be frozen all year round. When we land and begin to collect snow samples and a small ice core, however, we find we are digging into slush. The ice has started to melt up here, too. </p>
<p>We heave up our ice corer, and meltwater dribbles out from its bottom. In periods of extreme warming, much of the surface of the ice sheet can experience melting episodes, <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2015.00225/full">disturbing the slumbering microbes</a> stored within the otherwise permanently frozen surface. It’s a sobering moment for us all.</p>
<p>Flying back to camp, I watch the streams become rivers and lakes as we head back over the dark zone, where melt and microbes dominate the icescape. I contemplate how much water, once locked in the ice, will become free to flow into the sea and into millions of homes by the end of the century.</p>
<h2>Popping a pingo</h2>
<p>The frozen lands of eight nations encircle the Arctic. Their soils store vast quantities of carbon: a third of the planet’s entire quantity of soil carbon resides in this frozen ground.</p>
<p>The carbon is a legacy of soils formed in past climates and preserved for millennia. However, human-induced climate change is reheating this leftover carbon, providing a luxuriant food source for microbes resident within the <a href="https://earthobservatory.nasa.gov/biome/biotundra.php">tundra</a>, which then emit it as greenhouse gases.</p>
<p>This is known as the <a href="https://en.wikipedia.org/wiki/Permafrost_carbon_cycle#:%7E:text=Carbon%20emissions%20from%20permafrost%20thaw,which%20increases%20permafrost%20thaw%20depths.">permafrost carbon</a> feedback loop. When even modest quantities of this vast carbon store reach the atmosphere, warming accelerates – resulting in faster thawing of the tundra and the release of yet more greenhouse gases.</p>
<p>Furthermore, not all greenhouse gases are equal in their impact. While carbon dioxide is relatively abundant and stable for centuries in the atmosphere, methane is less abundant and shorter-lived, but remarkably powerful as a greenhouse gas – nearly 30 times more damaging to the climate than carbon dioxide, for the same volume.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist crouched on ice taking water samples." src="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=307&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=307&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=307&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=386&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=386&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532615/original/file-20230619-1823-ekek0j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=386&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Andy Hodson sampling methane from a freshly ‘popped’ pingo.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For more than three decades, <a href="https://www.unis.no/staff/andy-hodson/">Andy Hodson</a> has worked at the frontier where microbes, carbon and the Arctic landscape meet. In 2018, we join him on a brisk spring day in Svalbard. It’s -26°C but the snowmobile commute is thankfully brief – then we work quickly against the cold.</p>
<p>Hodson’s plan is to “pop” one of the many <a href="https://en.wikipedia.org/wiki/Pingo">pingos</a> that populate the floor of this wide open valley. Think of pingos as the acne of the Arctic: they form as permafrost compresses unfrozen wet sediments, erupting as small hills blistering the skin of the tundra.</p>
<p>The story of these microbes’ lives is complicated. They only live beyond the reach of oxygen – where oxygen is more prevalent, methane-consuming microbes thrive instead, quenching the belches of methane from below. Similarly, should mineral sources of iron or sulphide be nearby, then microbes that use them outcompete the methanogens.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small fountain of water in an opening in the ice, amid a snowy landscape." src="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532614/original/file-20230619-15-6i78fv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A popped pingo discharging supercooled water rich in methane.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It all adds up to one of the greatest uncertainties for our civilisation: the extent and composition of greenhouse gases escaping from Arctic lands. <a href="https://www.cam.ac.uk/research/news/emissions-from-melting-permafrost-could-cost-43-trillion#:%7E:text=Increased%20greenhouse%20gas%20emissions%20from,and%20the%20University%20of%20Colorado.">Estimates of the economic impacts</a> from this permafrost carbon feedback tally in the tens of trillions of dollars to the global economy. We know it is bad news, but exactly how bad depends on the microbes in their microscopic mosaic.</p>
<p>Hodson’s field work shows that, during the Arctic winter, this pingo is probably the only source of methane in the immediate area, its chimney enabling the gas to escape from the depths of the ice before methane-consuming microbes can catch it. Annually, tens of kilograms of methane and more than a ton of carbon dioxide will escape from this pingo alone - one of <a href="https://doi.org/10.1016/j.geomorph.2023.108694">more than 10,000</a> scattered across the Arctic, in addition to its other methane-producing hotspots.</p>
<h2>A near-perfect ecosystem</h2>
<p>Arctic lands are a patchwork of permafrost carbon feedbacks, and our future depends on the uncertain fate of the microbes within. </p>
<p>While the ice melt enhances the growth of microbes in the short term, if it continues to the point of erasing habitats then the microbes will be lost with them. We recognise this danger for polar bears and walruses, but not the invisible biodiversity of the Arctic. Small does not mean insignificant though.</p>
<p>To appreciate this, we can head back to the dark zone on Greenland’s ice sheet and join <a href="https://www.rolex.org/rolex-awards/exploration/joseph-cook">Joseph Cook</a> during our summer 2014 field season. He’s lying on a mat improvised from a bath towel and a binbag wrapped in duct tape, peering into a dark, pothole-like depression in the ice. It’s a cryoconite hole, and millions of them are dotted over the edges of the ice sheet. Where pingos contribute to climate warming by emitting methane, cryoconite is a good sink of greenhouse gases, but this creates its own problems. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Crouching scientist takes samples in the Arctic snow." src="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532618/original/file-20230619-27-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Joseph Cook measuring the carbon cycling activities of Greenland’s cryoconite holes.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2008.01758.x">earliest estimate</a> of its ability to store carbon dioxide from the air on the ice surface of the world’s glaciers exceeded Finland’s total carbon emissions in the same year. Every cryoconite hole is a near-perfect ecosystem – with a singular flaw. Its inhabitants must melt ice to live. But the very act of melting the ice hastens the demise of their glacier habitat. </p>
<p>Despite being found in some of the harshest locations on Earth, cryoconite is home for thousands of different types of bacteria (including the all-important photosynthetic cyanobacteria), fungi, and <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/protozoa.html">protozoa</a>. Even <a href="https://www.theguardian.com/environment/2020/oct/17/tardigrade-ice-hole-arctic-greenland">tardigrades</a> thrive in cryoconite.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscope image of a single cryoconite granule." src="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532623/original/file-20230619-21-7v4otj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microscope image of a cryoconite granule, showing biological darkening and cyanobacteria growing through it.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Cook is professionally besotted with the perfection of this near-frozen “microscopic rainforest”. Its inhabitants are shielded and nourished at just the right depth and in the right shape for a busy ecosystem to be engineered by the interaction of sunlight with cyanobacteria, dust and ice to the benefit of all its inhabitants. The cyanobacteria use sunshine to capture carbon dioxide from the air and convert it into the slimy cement that builds each granule of cryoconite</p>
<p>However, with vast numbers of cryoconite holes dotted across the ice surface, “swarms” of these holes help <a href="https://www.frontiersin.org/articles/10.3389/feart.2015.00078/full">shape and darken the ice surface</a>. This in turn influences the melting rate, as the surface is sculpted under the sun of 24-hour daylight.</p>
<p>Writing in the scientific journal <a href="https://www.nature.com/articles/029039a0">Nature in 1883</a>, Swedish polar explorer Adolf Erik Nordenskjöld, who discovered cryoconite, thanked the organisms within cryoconite for melting away the ancient ice that once covered Norway and Sweden:</p>
<blockquote>
<p>In spite of their insignificance, [they] play a very important part in nature’s economy, from the fact that their dark colour far more readily absorbs the Sun’s heat than the bluish-white ice, and thereby they contribute to the destruction of the ice sheet, and prevent its extension. Undoubtedly we have, in no small degree, to thank these organisms for the melting away of the layer of ice which once covered the Scandinavian peninsula.</p>
</blockquote>
<h2>Taking DNA analysis to strange new places</h2>
<p>We return to Greenland in winter 2018 to explore cryoconite’s singular flaw. Cook and I are joined by Melanie Hay, then a PhD student in Arctic bioinformatics.</p>
<p>Hay and I are taking DNA analysis to strange new places to learn more about the evolution and biology of cryoconite. Powerful advances in genomics are changing our view of the microbial world, but large DNA-sequencing instruments fare best in sophisticated labs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientist sitting outside her tent with backpack, looking out at icy landscape." src="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532619/original/file-20230619-17-uv14gu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Melanie Hay camping and sampling on the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Instead, we are using a stapler-sized nanopore sequencer hooked up to the USB port of a winterised laptop. Outside the tent, it is –20°C – but the DNA sequencer must run at body temperature. The only sustainable source of warmth is body heat, so I have snuggled up with the sequencer in my sleeping bag every night and in my clothes all day.</p>
<p>That evening, we are caught in a storm of hurricane force. Becoming disorientated while moving between tents would be lethal, so we crawl in a human chain through the whiteout to our sleeping tents. Hay reaches her tent but Cook’s is lost, so we squeeze into my one-person tent. Somehow I sleep soundly, while Cook is exposed to the full force of the night’s terror.</p>
<p>In the morning, we excavate Hay, whose snow-laden tent had collapsed in the night. The sequencing is complete, but storm damage to our generator means the camp is losing power, so she must work quickly. She identifies the cyanobacteria building the cryoconite – it’s a short list dominated by one species: <em>Phormidesmis priestleyi</em>.</p>
<p>This species, found in cryoconite throughout the Arctic, seems to be the ecosystem engineer of cryoconite – a microscopic beaver building a dam of dust. But the flaw is the darkness of the near-perfect cryoconite ecosystems it creates. Like the neighbouring glacier algae we met earlier, <em>Phormidesmis priestleyi</em> is biologically darkening Arctic ice, and eventually hastening the demise of the thousands of different types of organism contained in cryoconite holes.</p>
<p>And so, this work shows us ever more clearly that the <a href="https://www.nature.com/articles/s41559-020-1163-0">loss of the planet’s glaciers</a> is as much a component of the global biodiversity crisis as it is a headline impact of climate change.</p>
<h2>Last line of defence against antibiotic resistance</h2>
<p>The loss of the Arctic’s microbial biodiversity matters in other ways too. Hay and Aliyah Debbonaire are both reformed biomedical scientists seeking cures from the Arctic in the form of new antibiotics. In the summer of 2018, we are in Svalbard looking for clues.</p>
<p>The world is running out of effective antibiotics, and the Arctic’s frontiers may be our last line of defence in this antibiotic resistance crisis. Countless species of microbes have evolved to live within its harsh habitats using all the tricks in the book, including making antibiotics as chemical weapons to kill off competitors. This means they may be sources of new antibiotics.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Scientists (one kneeling) taking samples in the snowy Arctic landscape." src="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532631/original/file-20230619-1900-kr9gwx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aliyah Debbonaire (left) and Melanie Hay sampling a cryoconite hole.</span>
<span class="attribution"><span class="source">Arwyn Edwards</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>And this is not their only application. From cheeses to eco-friendly biological washing powders, entire shopping aisles of products have been derived from cold-adapted microbes. As climate warming threatens to disrupt entire Arctic habitats, our opportunity to use, learn from, and protect this biodiversity may be lost forever.</p>
<p>As our tiny plane returns to the nearest town, Longyearbyen, we fly low over the <a href="https://theconversation.com/after-svalbard-why-safety-of-world-seed-vaults-is-crucial-to-future-food-security-79586">Svalbard Global Seed Vault</a>, which contains the fruits of more than 12,000 years of agriculture in the form of seeds from a million different varieties of crop. Nearby, a similar facility inside a disused coal mine stores essential computer programmes on microfilm – the ultimate backup for our data-addicted world.</p>
<p>Within a snowy kilometre, you can walk between the the alpha and omega of human innovation in civilisation. Both facilities have chosen the fastest-warming town on the planet as the safest place to store these treasures of humanity. Yet no such facility is dedicated to the microbial biodiversity of the Arctic, despite its critical importance to the future of the world’s biotech and medical sectors.</p>
<p>Instead, it falls to microbiologists such as Debbonaire, racing against time to identify, nurture and screen the microbes of the melting Arctic. Her painstaking work accumulates towers of Petri dishes, each a temporary refuge for a different Arctic microbe.</p>
<p>Eventually, they will be stored in <a href="https://www.dellamarca.it/en/how-does-an-ultra-low-freezer-work/">ultra-freezers</a> in laboratories scattered across the world. Such work is unglamorous to funders, so it is done piecemeal on the edges of other projects. Yet it represents our only attempt to save the microbes of the Arctic.</p>
<h2>The battle is lost</h2>
<p>Most of all, the Arctic matters because it is the fastest-warming part of the planet, and its microbes are responding first. What happens there carries implications for everyone. It is the harbinger of change for everywhere.</p>
<p>Another Arctic microbiologist could strike plangent notes regarding permafrost or sea ice, but as an ecologist of glaciers I am drawn to glacial ice.</p>
<p>Over the first fifth of this century, Earth’s glaciers have discharged some ten quadrillion (ten to the power 25) tablespoons of melt a year – and within each tablespoon, the <a href="https://www.nature.com/articles/s43247-022-00609-0">tens of thousands of bacteria and viruses</a> that were once stored within that ice.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meltwater-is-infiltrating-greenlands-ice-sheet-through-millions-of-hairline-cracks-destabilizing-its-structure-207468">Meltwater is infiltrating Greenland’s ice sheet through millions of hairline cracks – destabilizing its structure</a>
</strong>
</em>
</p>
<hr>
<p>What’s to come is sadly predictable. Even the most modest warming scenario of 1.5°C above the pre-industrial era will lead to the extinction of at least <a href="https://www.science.org/doi/10.1126/science.abo1324">half the Earth’s 200,000 glaciers</a> by the end of the century.</p>
<p>Depending on the urgency and effectiveness of our actions as a civilisation, this century could also represent the “peak melt” in our history. Yet the battle to save many of these precious icy habitats is already lost. Instead, for scientists like me, our field work is now largely a question of documenting these “crime scenes” – so at least the knowledge of life within ice can be preserved, before it melts away forever.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>For you: more from our <a href="https://theconversation.com/uk/topics/insights-series-71218?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Insights series</a>:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/prehistoric-communities-off-the-coast-of-britain-embraced-rising-seas-what-this-means-for-todays-island-nations-147879?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Prehistoric communities off the coast of Britain embraced rising seas – what this means for today’s island nations
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<li><p><em><a href="https://theconversation.com/noise-in-the-brain-enables-us-to-make-extraordinary-leaps-of-imagination-it-could-transform-the-power-of-computers-too-192367?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Noise in the brain enables us to make extraordinary leaps of imagination. It could transform the power of computers too
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<p><em>To hear about new Insights articles, join the hundreds of thousands of people who value The Conversation’s evidence-based news. <a href="https://theconversation.com/uk/newsletters/the-daily-newsletter-2?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK"><strong>Subscribe to our newsletter</strong></a>.</em></p><img src="https://counter.theconversation.com/content/207785/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arwyn Edwards receives funding from UK Research & Innovation - Natural Environment Research Council, as well as the Research Council of Norway, the Leverhulme Trust, and the Royal Geographical Society. </span></em></p>To fully understand the extent of climate-related dangers the Arctic – and our planet – is facing, we must focus on organisms too small to be seen with the naked eye.Arwyn Edwards, Reader in Biology, Department of Life Sciences, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2049832023-05-11T12:59:30Z2023-05-11T12:59:30ZMicroplastics: we’ve found startling quantities in the ice algae that are essential for all Arctic marine life<p>Last summer, we travelled to the remote Arctic Hausgarten observatory area in the eastern Fram Strait (west of Svalbard, Norway) on a <a href="https://www.awi.de/en/expedition/research-vessel-and-cutter/polarstern.html">research ship</a>. The samples we collected there included ice cores, sea water and ice algae from large packs of floating ice called ice floes. These form 1–2 metre thick “plates” of sea ice across the Arctic Ocean, some of which melt over the summer period. </p>
<p>Algae grow on the underside of these ice floes. <em>Melosira arctica</em> – nicknamed “snot” due to its sticky, slimy and green nature – is one of the major algae species in the Arctic Ocean. It is an essential organism both in the Arctic food web and for marine life overall.</p>
<p>These ice algae provide nutrition for plankton and various other marine organisms in the Arctic. The algae also act as a <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0076599">conveyor belt of food</a> for the organisms that live on the sea floor. As the ice melts, the algae detach and sink to the bottom where they are eaten by animals such as <a href="https://www.britannica.com/animal/sea-cucumber">sea cucumbers</a> and <a href="https://www.britannica.com/animal/brittle-star">brittlestars</a>. </p>
<p>Ice algae are also a carbon sink, using CO₂ from the atmosphere and light energy from the sun to produce organic matter through photosynthesis – a process known in ecology as “<a href="https://www.nature.com/articles/s41467-023-37612-8">primary production</a>”. In 2012, these algae <a href="https://www.science.org/doi/10.1126/science.1231346">accounted for 45%</a> of the Arctic’s primary production.</p>
<p>But now <a href="https://pubs.acs.org/doi/10.1021/acs.est.2c08010">we’ve found</a> that Arctic ice algae contain microplastics. This in itself may not be surprising: plastic has been found in <a href="https://doi.org/10.1016/j.hazadv.2022.100057">every environment</a> so far investigated on Earth. But the quantities we found were startling. </p>
<p>We discovered an average of 31,000 microplastic particles per cubic metre of <em>Melosira arctica</em> – a magnitude ten times higher than recorded in the surrounding water. Most of these particles were very small (less than 10 micrometres) and included many different types of plastic. The contamination of the ice algae could have major consequences for ecosystems and the climate.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four images of Melosira arctica algae." src="https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524606/original/file-20230505-15-3dxxqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Melosira arctica</em>, one of the major algae species in the Arctic Ocean.</span>
<span class="attribution"><span class="source">Melanie Bergmann</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>An elevator to the seabed</h2>
<p>These particles may come from the surrounding sea water, the <a href="https://www.nature.com/articles/s41467-018-03825-5">supporting sea ice</a> (either trapped when the sea ice forms, or from the movement of liquid and particles through the ice as it melts), or from <a href="https://www.nature.com/articles/s43017-022-00292-x">atmospheric microplastics</a> that have been deposited on the ice and sea surface. While the process by which sea ice algae take in these microplastics is not yet well understood, it is clear they are highly effective at “collecting” these small plastic particles.</p>
<p>In <a href="https://pubs.acs.org/doi/10.1021/acs.est.9b06981">our earlier research</a>, we were puzzled that the largest amount of microplastic on the Arctic seabed was always found underneath the sea ice melting zone along the ice edge, even in deep-sea sediment. The movement of <em>Melosira</em> clumps from the sea and ice surface to the seabed helps to explain why. </p>
<p>The speed at which the algal clumps descend means they fall rapidly almost in a straight line below the edge of the ice. Other algae, which become “marine snow” (a term used for organic material that slowly drifts to the seafloor), fall much slower. These are often eaten as they descend and are also pushed sideways by currents, so sink to the seabed much further away from the ice edge.</p>
<figure class="align-center ">
<img alt="A graph showing how microplastics could become trapped in Arctic sea ice algae and sink to the seabed." src="https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524607/original/file-20230505-25-au50ge.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">How microplastics could become trapped in Arctic sea ice algae and sink to the seabed.</span>
<span class="attribution"><a class="source" href="https://creativecommons.org/licenses/by/4.0/">Bergmann et al. (2023)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>Why is it a problem?</h2>
<p><em>Melosira</em> feeds essential Arctic <a href="https://link.springer.com/article/10.1007/s00300-014-1634-3">seafloor</a> and marine ecosystems. Its position at the bottom of the food chain means there is a risk of microplastics being passed upwards through the marine food web.</p>
<p>This threat is particularly acute in the area we studied, as the <em>Melosira</em> sampled had collected even very small microplastics. Smaller microplastic particles are more likely to be transferred across cell membranes.</p>
<figure class="align-center ">
<img alt="Three researchers on an Arctic ice floe sampling for ice algae." src="https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524603/original/file-20230505-23-3dxxqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ice algae sampling on an Arctic ice floe.</span>
<span class="attribution"><span class="source">Mario Hoppmann/Alfred Wegener Institute</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Research finds that microplastics and their associated chemicals can alter the <a href="https://zenodo.org/record/5898684#.YjRGUzUxl6X">growth, function and breeding</a> of marine species such as plankton and fish. It is extremely difficult to perform experiments on Arctic or deep-sea species because of the challenges associated with replicating their environmental conditions. However, <a href="https://www.sciencedirect.com/science/article/pii/S0166445X20303817">one laboratory study</a> found that microplastic exposure caused egg production rates to increase by up to eight times in Arctic zooplankton – a response that is probably the result of stress. </p>
<p>The impact of microplastic contamination on <em>Melosira</em> itself is not yet known. But it’s possible that microplastics change <em>Melosira’s</em> abundance, lifespan and health. </p>
<p>Microplastics that are stuck to the outside of algae could lower photosynthetic rates by blocking out sunlight. And if particles enter the algal cells, then they could damage the parts of the cell where photosynthesis takes place (called chloroplasts) and therefore also impede this process. This could affect the export of carbon by <em>Melosira</em> from the air or sea to the seabed, and thus alter the processes underlying this important Arctic carbon sink.</p>
<p>Arctic ice algae are collecting high quantities of microplastics – a previously unknown hotspot. But our findings are likely just the “tip of the iceberg”. They should accelerate conversations about the importance, and potential impact, of microplastics in Arctic sea ice algae on the ecosystems that these vital algae support.</p><img src="https://counter.theconversation.com/content/204983/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Deonie Allen received funding from Leverhulme Trust through grant ECF-2019-306 and the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 101023635.</span></em></p><p class="fine-print"><em><span>Melanie Bergmann receives funding from German Government via the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research. </span></em></p><p class="fine-print"><em><span>steve allen receives funding from the Canadian government through Ocean frontiers Institute.</span></em></p>Arctic sea ice algae contaminated with microplastics have serious consequences for ecosystems and the climate.Deonie Allen, Research Fellow in Geography, Earth and Environmental Sciences, University of BirminghamMelanie Bergmann, Senior Scientist, Alfred Wegener Institute Helmholtz Centre for Polar and Marine ResearchSteve Allen, Ocean Frontier Institute researcher, Dalhousie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2044122023-05-09T18:23:08Z2023-05-09T18:23:08ZClimate: modelling micro-algae to better understand the workings of the ocean<figure><img src="https://images.theconversation.com/files/525196/original/file-20230509-21-koy7o5.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C1920%2C1258&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Diazotroph (_Trichodesmium_) bloom in the Coral Sea, captured on 1 September 2019 by the Landsat 8 satellite. The interaction between the physics and biology of the ocean is manifested in these green filaments that snake through the currents.</span> <span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/images/145610/a-bloom-of-nitrogen-fixing-bacteria">Joshua Stevens/NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The ocean absorbs <a href="https://www.nature.com/articles/s43017-022-00381-x">a quarter of the CO₂</a> given out by human activities, playing a major role in slowing climate change. To have a better grasp of these processes is crucial to understand the ocean’s role in the global climate system and to better foresee disruptions caused by the changing climate.</p>
<p><a href="https://theconversation.com/les-oceans-bientot-dotes-de-jumeaux-virtuels-pour-quoi-faire-160425">Numerical modeling</a> is among the most frequently used tools to do this. Through quantitive methods, it can simulate the interactions of important drivers of the climate, including atmosphere, oceans, land surface and ice. It represents the climate on a virtual planet earth, and is indispensable to explore past and predict future conditions, and to understand how our current climate works.</p>
<h2>The challenge of modelling the oceans</h2>
<p>These models rely on a series of equations governing the main physical, chemical and biological phenomena shaping the world’s climate. The difficulty of representing these forces comes from the complexity of simulating the physical and biological processes involved and how they interact with each other.</p>
<p>As far as the physics of the oceans is concerned, the equations are fairly well known and defined. Improving models depends above all on higher resolution, limited for the moment by the processing capacity and storage space of our computers.</p>
<p>When it comes to biological factors, however, there are lots of questions around how best to encode and simplify processes of the highest complexity. To boil it down: CO<sub>2</sub> capture is principally regulated by phytoplankton. These microscopic algae live on the surface areas of the ocean and absorb CO<sub>2</sub> via photosynthesis. When phytoplankton die, some of the organisms fall to the bottom of the ocean, providing a carbon store for hundreds, indeed thousands of years.</p>
<p>To represent phytoplankton, one of the commonest approaches is to divide it into “functional types” – that’s to say distinct groups of phytoplankton which have features in common such as size or feeding strategy. This approach assumes each type can have a different impact on the carbon cycle and play a different role in the ecosystem.</p>
<h2>Diazotrophs – allies of the climate</h2>
<p>One type in particular, diazotrophs, are under the spotlight at the moment. These organisms, as their name indicates, use nitrogen (N2) molecules for their growth (etymologically speaking, for feeding, from the Greek word <em>trophos</em>). By transforming N2, diazotrophs provide nutrients that are essential to other phytoplankton and allow them to photosynthesise. They thus have a fundamental role as natural fertilisers of the ocean.</p>
<p>Recent studies, in the field and the lab, have shown the great diversity of diazotrophs and their <a href="https://www.science.org/doi/10.1126/science.aay9514">adaptation to different environments</a>. For example, while it was previously thought diazotrophs were confined to warm, clear tropical waters, some unicellular diazotrophs have been discovered in <a href="https://www.pnas.org/doi/10.1073/pnas.1813658115">Arctic seas</a> or in the darkness of the <a href="https://ami-journals.onlinelibrary.wiley.com/doi/full/10.1111/1462%E2%80%932920.15645">deep ocean</a>.</p>
<p>For a long time, however, researchers have taken the view that diazotrophs contribute little to carbon sequestration, because <em>Trichodesmium</em> – historically the most studied diazotroph – tends to stay on the ocean surface and to be little subject to predation. But evidence has been gathered and shows other types of diazotroph (those in symbiosis with diatom algae) are involved in <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053356">significant carbon flows</a> toward the depths).</p>
<p>Despite their importance, diazotrophs are often represented in a very sketchy way in numerical models. This is a result of both our understanding of their physiology still being limited, and constraints in computing capacity – when one adds complexity to the models, simulations take more time or need more powerful processors.</p>
<p>Many Earth System models, like those used by the Intergovernmental Panel on Climate Change, still work on the basis of assuming that nitrogen is artificially added to the ocean’s surface in certain conditions supposedly favourable to diazotrophs.</p>
<p>Other models explicitly represent the nitrogen-fixing process, but restrict themselves to a single type of diazotroph with the characteristics of <em>Trichodesmium</em>. This is, however, a very reductive approach given scientific advances, and limits our capacity to capture the global distribution of microalgae, assess their impact on the rest of the ecosystem, and to predict the consequences of climate change both on phytoplankton and carbon sequestration.</p>
<h2>Better representation of diazotrophs in digital models</h2>
<p>To address these gaps, we have developed within the framework of project <a href="https://twitter.com/notion_project?lang=fr">NOTION</a> a brand new representation of diazotrophs, this time including three different types.</p>
<figure class="align-center ">
<img alt="Schematic drawing of the Pacific Ocean with bands of colour extending between Central America and Central Africa, with another shorter band at the latitude of Spain" src="https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=559&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=559&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=559&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=702&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=702&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517767/original/file-20230327-1352-kegjgq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=702&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Estimated nitrogen fixation rate for a day in November under average conditions. Each colour corresponds to a different type of diazotroph. Sometimes the bands overlap, indicating a mixture of diazotroph species.</span>
<span class="attribution"><span class="source">Domitille Louchard, Mar Benavides</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>If the equations describing diazotroph growth and mortality are the same, each type is distinguished from the others by specific factors, corresponding to how each type reacts to different temperatures, amount of sunlight or availability of nutrients.</p>
<p>This innovative representation of diazotrophs has been integrated into a high-resolution numerical model applied to the Atlantic Ocean – a diazotroph hotspot.</p>
<p>Accounting for the diversity of diazotrophs has resulted in an expansion of nitrogen fixing in digital models of the ocean, and closer accordance with field observations. Estimates of vertical carbon flows have also increased, notably in regions like the tropical West Atlantic, where diazotrophs in symbiosis with diatom algae flourish.</p>
<figure class="align-center ">
<img alt="Schematic drawing of the Pacific Ocean as in Figure 2. The presence of fixed nitrogen increases strongly from April, then falls back again from November" src="https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=560&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=560&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=560&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=703&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=703&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517428/original/file-20230324-22-ibaffr.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=703&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A year of surface nitrogen fixation using the new digital system developed within the Project NOTION framework. Simulation by Domitille Louchard at ETH Zurich.</span>
<span class="attribution"><span class="source">Domitille Louchard, Mar Benavides</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>The new model allows us to address understudied issues, such as competition between diazotrophs, but also to better understand the role microalgae play in the context of a changing planet. What is their importance as a source of nitrogen going to be for other producers at the bottom of the food chain? Can diazotrophs help limit the effects of climate change? The possibilities for further research opened up by this more realistic representation are huge.</p>
<hr>
<p><em>The NOTION research project described in this article is generously supported by <a href="https://group.bnpparibas/decouvrez-le-">Foundation BNP Paribas</a> as part of its <a href="https://group.bnpparibas/tempsforts/climate-biodiversity">Climate and Biodiversity Initiative</a>.</em></p>
<hr>
<p>Translation by <a href="https://twitter.com/JoshNeicho">Joshua Neicho</a></p><img src="https://counter.theconversation.com/content/204412/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Domitille Louchard has received funding from the BNP Paribas Foundation (Climate & Biodiversity initiative).</span></em></p><p class="fine-print"><em><span>Mar Benavides a reçu des financements de Climate & Biodiversity Initiative Fondation BNP Paribas, projet NOTION.</span></em></p>The ocean absorbs a quarter of the CO₂ emitted by humans, thanks in particular to phytoplankton, including diazotrophs. Knowing how to model them is crucial to understanding the ocean’s role in climate.Domitille Louchard, Assistant researcher, Swiss Federal Institute of Technology ZurichMar Benavides, Research scientist, Institut de recherche pour le développement (IRD)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034922023-05-03T12:07:00Z2023-05-03T12:07:00ZHeading to a beach this summer? Here’s how to keep harmful algae blooms from spoiling your trip<figure><img src="https://images.theconversation.com/files/523475/original/file-20230428-22-cp3c0a.jpg?ixlib=rb-1.1.0&rect=35%2C0%2C5862%2C3926&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warning sign at Lido Key Beach in Sarasota, Fla., March 15, 2023, during a toxic algae bloom.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sign-warning-of-the-red-tide-risk-is-displayed-at-lido-key-news-photo/1248835855"> Jesus Olarte/AFP via Getty Images</a></span></figcaption></figure><p>Plunging into the ocean or a lake is one of the great joys of summer. But arriving at the beach to find water that’s green, red or brown, and possibly foul-smelling, can instantly spoil the party.</p>
<p>As a <a href="https://www.researchgate.net/profile/Brad-Reisfeld">toxicologist</a>, I study health risks from both synthetic and natural substances. I’ve conducted research into <a href="https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract_id/11137/report/0">early detection of harmful algal blooms</a>, or HABs, which are an increasing threat to humans, animals and the environment. </p>
<p>Toxins produced during these blooms have been implicated in human and animal illnesses in at least 43 states. Scientists have estimated that in the U.S. alone, freshwater HABs cause more than <a href="https://meetings.pices.int/publications/other/members/HAB-PolicyMakers.pdf">US$4.6 billion in damage yearly</a>. Here’s what to know about them if you’re bound for the water’s edge this summer.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/KfbM32b50fY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Harmful algal blooms have become a regular occurrence along large stretches of Florida’s coast in recent years.</span></figcaption>
</figure>
<h2>Tiny organisms, big impacts</h2>
<p>Algae and cyanobacteria – often called blue-green algae – are simple, plantlike organisms that live in water. They can grow out of control, or “bloom,” especially when the water is warm and slow moving. Climate change is <a href="https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/">making water bodies warmer</a>, increasing the risk of HABs. </p>
<p>The other major factor that drives blooms is high levels of nutrients like nitrogen and phosphorus, which fertilize algae. <a href="https://www.epa.gov/sites/default/files/2015-03/documents/facts_about_nutrient_pollution_what_is_hypoxia.pdf">Nutrient pollution</a> comes mainly from agriculture, wastewater treatment plants, septic systems and fossil fuel combustion.</p>
<p>Sometimes these blooms contain organisms that produce toxins – an umbrella term for many poisonous substances that <a href="https://medlineplus.gov/ency/article/002331.htm">come from animals or plants</a> and can make people and animals sick and adversely affect the environment. These events are called harmful algal blooms. </p>
<p>HABs occur <a href="https://hab.whoi.edu/maps/regions-us-distribution/">throughout the U.S.</a> and <a href="https://hab.whoi.edu/maps/regions-world-distribution/">worldwide</a>, in both saltwater and freshwater environments. They pose significant health risks to human, pets, livestock and wildlife; damage ecosystems; increase water treatment costs; restrict recreational activities; and cut into economic revenues.</p>
<p>People and animals can be exposed to HAB toxins through many routes. These include skin contact during activities such as swimming or boating; inhaling airborne droplets that contain toxins; swallowing contaminated water; or eating food or supplements that contain toxins. The most severe effects generally result from <a href="https://hab.whoi.edu/impacts/impacts-human-health/">consuming contaminated seafood</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1156634023189504003"}"></div></p>
<h2>An array of toxins</h2>
<p>There are numerous <a href="https://www.cdc.gov/habs/pdf/ohhabs-algae-algal-toxins-and-other-pathogens-lists.pdf">HAB toxins</a>, including substances such as microcystin, saxitoxin, cylindrospermopsin, anatoxin-A and domoic acid. Each has a different action on the body, so HABs can have <a href="https://mywaterquality.ca.gov/habs/resources/docs/humanhealth/hab_physician_guide_may2020.pdf">diverse harmful effects</a>.</p>
<p>Typical <a href="https://www.cdc.gov/habs/illness.html">symptoms of illness</a> from exposure to HAB toxins can include stomach pain, vomiting or diarrhea; headache, fever, tiredness or other general symptoms; skin, eye, nose or throat irritation; and neurological symptoms such as muscle weakness or dizziness. Depending on the toxin, higher levels of exposure can result in tremors or seizures, respiratory distress, kidney toxicity, liver toxicity and even death.</p>
<p>As with many environmental exposures, children and older people may be especially sensitive to HAB toxins. People who regularly consume seafood caught in HAB-prone areas are also at risk of long-term health effects from potentially frequent, low-level exposures to HAB toxins.</p>
<h2>Recognizing and responding to HABs</h2>
<p>It’s not possible to tell whether a bloom is harmful just by looking at it, but there are some warning signs. If the water appears green, red, brown or yellowish in color; has a strong musty or fishy odor; has foam, scum, algal mats or paintlike streaks on the surface; or if there are dead fish or other marine life in the water or washed up on the shoreline, it’s likely that a HAB may be occurring.</p>
<p>If you are unsure whether a bloom is harmful or not, contact your local health department or environmental agency for guidance. As a general rule, it’s good to check with local agencies to see whether there are any relevant warnings when you go to the beach. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Cqv2IclhKUm/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>If you are notified of a bloom in a nearby body of water or in your public drinking water supply, the most important thing you can do to reduce your chances of getting sick is to follow local or state guidance. If you see signs of a bloom, stay out of the water and keep your pets out of the water.</p>
<p>It’s also important to follow local guidelines about consuming seafood caught through recreational fishing. It’s important to be aware that cooking contaminated seafood or boiling contaminated water <a href="https://www.webmd.com/food-recipes/food-poisoning/red-tide">does not destroy the toxins</a>. </p>
<h2>Be informed</h2>
<p>The U.S. Centers for Disease Control and Prevention provides <a href="https://www.cdc.gov/habs/general.html">resources and recommendations</a> related to HABs and ways to stay safe. Pet owners should also learn <a href="https://www.dec.ny.gov/docs/water_pdf/habspets.pdf">how to protect their dogs from HABs</a>. </p>
<p>Other federal agencies that offer information about HABs include <a href="https://hab.whoi.edu/">the U.S. National Office for Harmful Algal Blooms</a> and the <a href="https://www.niehs.nih.gov/health/topics/agents/algal-blooms/index.cfm">National Institute of Environmental Health Sciences</a>.</p>
<p>Many states conduct <a href="https://www.epa.gov/cyanohabs/state-habs-monitoring-programs-and-resources">HAB monitoring programs</a>, especially in areas that are known to be vulnerable to blooms, such as <a href="https://ohioseagrant.osu.edu/products/1h6jc/what-are-habs">western Lake Erie</a>. The U.S. Environmental Protection Agency offers <a href="https://www.epa.gov/cyanohabs/state-habs-resources">HAB resources by state</a>. Apps used by water quality managers and state officials who make management decisions about public water supply safety, including <a href="https://play.google.com/store/apps/details?id=com.topcoder.epa">CyAN Android</a> and <a href="https://qed.epa.gov/cyanweb/">CyANWeb</a>, may contain useful information about HABs in your area.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1440401749328601088"}"></div></p>
<h2>What’s being done about HABs?</h2>
<p>Many efforts are underway to prevent, control and mitigate HABs and provide early warnings to water system managers and health officials. </p>
<p>One example in the U.S. is the
<a href="https://www.epa.gov/water-research/cyanobacteria-assessment-network-cyan">Cyanobacteria Assessment Network, or CyAN</a>, a collaborative effort across several government agencies to develop an early warning indicator system to detect algal blooms in freshwater systems. There are also several ongoing projects for <a href="https://coastalscience.noaa.gov/science-areas/habs/hab-forecasts/">HAB forecasting by region</a>.</p>
<p>At the global scale, the <a href="https://data.hais.ioc-unesco.org/">Harmful Algal Information System</a> will eventually include harmful algal events and information from harmful algae monitoring and management systems worldwide.</p>
<p>Citizen scientists can provide invaluable help by monitoring local waters. If you would like to participate, consider joining the <a href="https://coastalscience.noaa.gov/monitoring-and-assessments/pmn/">Phytoplankton Monitoring Network</a> or <a href="https://cyanos.org/bloomwatch/">the Cyanobacteria Monitoring Collaborative</a>, and download and use the
<a href="https://cyanos.org/bloomwatch/">Cyanobacterial bloom app</a> to report potential HABs in bodies of water you visit.</p><img src="https://counter.theconversation.com/content/203492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reisfeld received funding from the US Environmental Protection Agency to work on a project related to HABs detection</span></em></p>The tiny organisms that cause harmful blooms of algae can have a big impact on your trip to the shore. A toxicologist explains what causes these events and how to keep people and pets safe.Brad Reisfeld, Professor of Chemical and Biological Engineering, Biomedical Engineering, and Public Health, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1924922023-01-23T19:10:29Z2023-01-23T19:10:29ZThe food systems that will feed Mars are set to transform food on Earth<figure><img src="https://images.theconversation.com/files/504939/original/file-20230117-14-bdarwc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2000%2C1425&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Growing food in space will rely on innovative agricultural technologies.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/feature/students-help-solve-space-farming-challenges">(NASA)</a></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/the-food-systems-that-will-feed-mars-are-set-to-transform-food-on-earth" width="100%" height="400"></iframe>
<p>Could we feed a city on Mars? This question is central to the future of space exploration and has serious repercussions on Earth too. To date, a lot of thought has gone into <a href="https://www.atlasobscura.com/articles/what-do-astronauts-eat">how astronauts eat</a>; <a href="https://www.nasa.gov/mission_pages/station/research/benefits/so-you-want-to-be-a-space-farmer">however, we are only beginning to produce food in space</a>.</p>
<p>Space launches <a href="https://www.nbcnews.com/science/space/space-launch-costs-growing-business-industry-rcna23488">are quite expensive</a>. And with the growing desire to establish a human presence in space, we are going to have to consider food production in space. But the challenges are vast, requiring research into how plants respond to a variety of changes including to <a href="https://modernfarmer.com/2022/02/cotton-in-space/">gravity</a> and <a href="https://agrilifetoday.tamu.edu/2022/12/20/exploring-the-impact-of-space-radiation-on-plants/">radiation</a>.</p>
<p>As food and agriculture researchers, we explored this question in our latest book, <a href="https://ecwpress.com/products/dinner-on-mars"><em>Dinner on Mars</em></a>. We believe that a sustainable Martian food system is possible — and that in building it, we’ll change food systems on Earth. However, this will take some out-of-the-box thinking.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-are-going-back-to-the-moon-and-beyond-but-how-will-we-feed-them-189794">Humans are going back to the Moon, and beyond – but how will we feed them?</a>
</strong>
</em>
</p>
<hr>
<h2>Martian agriculture</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Book cover image showing an astronaut holding a fork and the title DINNER ON MARS" src="https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=927&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=927&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=927&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1165&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1165&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502316/original/file-20221221-13-qemw5z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1165&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">To explore Mars, we’ll need a sustainable Martian food system.</span>
<span class="attribution"><a class="source" href="https://ecwpress.com/products/dinner-on-mars">(ECW Press)</a></span>
</figcaption>
</figure>
<p>The basis of food systems on Mars would involve water harvested from the soil (<a href="https://news.asu.edu/20221219-nasas-curiosity-rover-discovers-waterrich-fracture-halos-gale-crater">rovers have shown that there are small but significant amounts of frozen water in the crust</a>) and <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/cyanobacteria">cyanobacteria, often referred to as blue-green algae</a>. </p>
<p>On earth, cyanobacteria can be a big problem as it grows in polluted waterways causing <a href="https://oceanservice.noaa.gov/facts/eutrophication.html">eutrophication — a nutrient-induced increase in phytoplankton productivity in the water body</a>. </p>
<p>On Mars, however, cyanobacteria can use the carbon dioxide in the atmosphere and grow on the sandy inorganic and toxic regolith — <a href="https://mars.nasa.gov/mars2020/mission/status/424/the-robotics-of-sampling-regolith/">the layer of loose rocks and dust covering bedrock</a> — to produce the basic organic molecules on which the rest of the food system will rest. </p>
<p>Cyanobacteria is capable of <a href="https://doi.org/10.3389/fmicb.2021.611798">growing in Martian conditions</a>, which has the very real added benefit of <a href="https://doi.org/10.1017/S1473550420000300">neutralizing extremely toxic chemicals called perchlorates</a>. Perchlorates are laced throughout <a href="https://www.space.com/21554-mars-toxic-perchlorate-chemicals.html">the Martian regolith and are toxic to humans in minute quantities</a>, so having cyanobacteria provide a double duty of neutralizing the toxins while producing organic material will be a huge boon to any Martian community.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an illustration showing a toxic, arid, reddish landscape including a toxic waste symbol on the left, and a lush, fertile, green landscape on the right with a cross-section of healthy, bacteria-filled soil" src="https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=379&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=379&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504788/original/file-20230116-16-u1cjp7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=379&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cyanobacteria can help detoxify the environment on Mars.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/directorates/spacetech/niac/2017_Phase_I_Phase_II/Mars_Soil_Agriculture/">(NASA/Adam Arkin)</a></span>
</figcaption>
</figure>
<h2>Greenhouse technologies</h2>
<p>Once bacteria are happily growing away under a Martian sky, they will provide nutrients needed to support luxurious crops of plants. A Martian city could be imagined as a lush green place, with hydroponics and soil-bound crops filling tunnels, carpeting domed craters and growing away in every unused corner. </p>
<p>Advanced greenhouse technologies — <a href="https://www.sciencefocus.com/science/what-is-vertical-farming/">like vertical agriculture</a> — that create a <a href="https://www.forbes.com/sites/jordanstrickler/2020/08/28/high-tech-greenhouses-could-be-the-future-of-agriculture/">suitable controlled environment</a> will provide abundant leafy greens, vegetables, fruits and specialty crops such as herbs, coffee and chocolate.</p>
<p><a href="https://modernfarmer.com/2023/01/grain-farming-goes-indoors/">Carbohydrates might be in short supply, however, as they take up large amounts of space</a>. Our grain consumption is likely to be lower on Mars, though legumes and grains will still appear in Martian diets in smaller quantities reflecting what can economically be produced on site. </p>
<p><a href="https://www.digitaltrends.com/web/agriculture-on-mars/">All plants on Mars will also play key roles in oxygen generation, water recycling and the provision of raw organic material for manufacturing</a></p>
<p>These technologies are also valuable on Earth as we attempt to shorten supply chains and improve the availability of healthy fruit and vegetables in the winter months.</p>
<h2>Meat on Mars?</h2>
<p>Animal agriculture is <a href="https://doi.org/10.1126/science.aaq0216">notoriously inefficient</a>. On Earth, <a href="https://www.theguardian.com/environment/2018/may/31/avoiding-meat-and-dairy-is-single-biggest-way-to-reduce-your-impact-on-earth">billions of domestic animals</a> threaten natural biodiversity, contribute to climate change and suffer from needless animal cruelty.</p>
<p>Animal-based systems will not be viable on Mars, but protein could be abundantly produced through cellular agriculture and precision fermentation. <a href="https://www.forbes.com/sites/forbestechcouncil/2023/01/18/understanding-the-cellular-agriculture-industrys-impact-and-growth/?sh=6cc70d02696f">Precision fermentation</a> involves creating proteins by utilizing modified yeasts, fungus and bacteria that consume starches and sugars — on Mars, this will largely come from <a href="https://www.foodnavigator-usa.com/Article/2022/11/28/watch-next-gen-biomanufacturing-from-lower-cost-feedstocks-for-precision-fermentation-to-cell-free-approaches">food waste</a> — and turn them into desired proteins. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kTu3X6yy3fQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Start-up companies are already making real dairy products without using cows.</span></figcaption>
</figure>
<p>Cellular agriculture <a href="https://www.bbc.com/future/article/20211116-how-the-food-industry-might-cut-its-carbon-emissions">involves taking stem cell samples and growing them in the lab to create cuts of meat identical to those from animal agriculture</a>.</p>
<h2>Reducing inefficiencies</h2>
<p>Imagining what agriculture could be like on Mars is a fascinating project, but it’s when we think about how these technologies may affect life on Earth that this topic becomes extremely serious. This is because on Mars — where each gram of organic matter, millilitre of water and photon of solar energy is scarce — there can be no inefficiencies.</p>
<p>The “waste” products of one part of the system need to be deliberately used as inputs into another part, such as using the dead cyanobacteria as a growth medium for later parts of the food system. But more than the technologies themselves, it may be the mindset of building a Martian food system that will change how things are done here on Earth, <a href="https://doi.org/10.1146/annurev-environ-101718-033228">where one-third of all food is thrown away</a>.</p>
<p>Our excitement about food technologies comes through in <em>Dinner on Mars</em>, but we are not techno-optimists. Technology isn’t a panacea. For example, if technologies like vertical farming reduce the need for farmland, then policies are required to ensure that the land will not just be paved over. </p>
<p>We also need to be mindful of the negative impacts of technologies, and be sensitive to how people’s livelihoods may need to change and adapt. Helping manage this transition and minimize disruption is another important area for policy. </p>
<p>The technologies unlocked by Mars, together with equitable policies, could place us on a much more sustainable trajectory on Earth.</p><img src="https://counter.theconversation.com/content/192492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lenore Newman consults with a range of agritech companies and receives funding from Genome BC and SSHRC.</span></em></p><p class="fine-print"><em><span>Evan Fraser consults with a range of vertical farming companies and initiatives including the Weston Family Foundation's Home Grown Innovation Challenge and Cubic Farms. He receives funding from a range of governmental and philanthropic sources including the Canada First Research Excellence Fund, the Social Sciences and Humanities Research Council and the Arrell Family Foundation. He is affiliated with the Canadian Food Policy Advisory Council, Protein Industries Canada, Genome Quebec, and the Maple Leaf Centre for Action on Food Security.</span></em></p>Agricultural technologies to grow food on Mars can help address climate change, sustainability and food scarcity challenges.Lenore Newman, Director, Food and Agriculture Institute, University of The Fraser ValleyEvan Fraser, Director of the Arrell Food Institute and Professor in the Dept. of Geography, Environment and Geomatics, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1883402022-10-24T12:27:57Z2022-10-24T12:27:57ZGeoengineering the ocean to fight climate change raises serious environmental justice questions<figure><img src="https://images.theconversation.com/files/489457/original/file-20221012-17-7piebk.jpg?ixlib=rb-1.1.0&rect=816%2C0%2C5465%2C3559&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">We could sink more carbon in the ocean to fight climate change, but should we?</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/fishermen-coming-back-to-the-beach-sland-of-mozambique-news-photo/617964338?phrase=ocean%20fishermen%20island">Eric Lafforgue/Art in All of Us/Corbis via Getty Images</a></span></figcaption></figure><p>Heat waves, droughts and extreme weather are <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-ii/">endangering people and ecosystems</a> somewhere in the world almost every day. These extremes are exacerbated by climate change, driven primarily by increasing emissions of greenhouse gases that build up in the atmosphere and trap heat at the Earth’s surface. </p>
<p>With that in mind, researchers are <a href="https://www.bostonglobe.com/2022/10/20/business/hubspots-brian-halligan-gets-real-about-climate-change/">exploring ways</a> to pull carbon dioxide out of the atmosphere and lock it away – <a href="https://nap.nationalacademies.org/catalog/26278/a-research-strategy-for-ocean-based-carbon-dioxide-removal-and-sequestration">including using the ocean</a>. But while these techniques might work, they raise serious technical, social and ethical questions, many of which have no clear answers yet.</p>
<p>We study climate change <a href="https://scholar.google.com/citations?user=1nrd2msAAAAJ&hl=en">policy, sustainability</a> and <a href="https://scholar.google.com/citations?user=VADzLZAAAAAJ&hl=en">environmental justice</a>. Before people start experimenting with the health of the ocean, there are several key questions to consider.</p>
<h2>Ocean carbon dioxide removal 101</h2>
<p>The ocean covers about 70% of the planet, and it <a href="https://earthobservatory.nasa.gov/features/OceanCarbon">naturally takes up carbon dioxide</a>. In fact, <a href="https://www.nature.com/articles/s41467-020-18203-3#Sec2">about a quarter</a> of human-produced carbon dioxide ends up in the ocean.</p>
<p>Ocean carbon dioxide removal is any action designed to use the ocean to remove even more carbon dioxide from the atmosphere than it already does and store it. </p>
<p>It spans a wide range of techniques – from increasing the amount and vitality of carbon dioxide-absorbing <a href="https://doi.org/10.1002/wcc.529">mangrove forests</a> to using <a href="https://nap.nationalacademies.org/catalog/26278/a-research-strategy-for-ocean-based-carbon-dioxide-removal-and-sequestration">ocean fertilization</a> to stimulate the growth of phytoplankton that absorb carbon dioxide to building pipelines that pump <a href="https://digitalcommons.mainelaw.maine.edu/oclj/vol12/iss2/3/">liquid carbon dioxide into formations under the seabed</a>, where it can eventually solidify as carbonate rock.</p>
<figure class="align-center ">
<img alt="A cross-section of ocean showing different types of carbon capture, like ocean fertilization" src="https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/483878/original/file-20220912-10060-hpa6op.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Methods of ocean direct carbon removal.</span>
<span class="attribution"><a class="source" href="https://www.frontiersin.org/articles/10.3389/fclim.2021.664456/full">2021 Boettcher, Brent, Buck, Low, McLaren and Mengis, Frontiers, 2021</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>There are other forms of carbon dioxide removal – planting trees, for example. But they <a href="https://www.ipcc.ch/srccl/">require large amounts of land</a> that is needed for other essential uses, such as agriculture.</p>
<p>That’s why <a href="https://www.nationalacademies.org/news/2021/12/new-report-assesses-the-feasibility-cost-and-potential-impacts-of-ocean-based-carbon-dioxide-removal-approaches-recommends-u-s-research-program">interest in using the vast ocean is growing</a>.</p>
<h2>Would these methods store enough carbon?</h2>
<p>The first crucial question is whether ocean carbon dioxide removal techniques could significantly reduce atmospheric carbon dioxide and store it long term, beyond what the ocean already does. Greenhouse gas <a href="https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_SPM.pdf">emissions are still increasing globally</a>, which means that ocean carbon dioxide removal would need to keep carbon dioxide out of the atmosphere for a long time, at least until greenhouse gas emissions have fallen.</p>
<p>Initial evidence suggests that some forms of ocean carbon dioxide removal, such as those that rely on short-lived biomass like kelp forests or phytoplankton, <a href="https://doi.org/10.1098/rsbl.2018.0781">may not keep captured carbon stored</a> for more than a few decades. That’s because most plant tissues are quickly recycled by decay or by sea creatures grazing on them.</p>
<p>In contrast, mechanisms that form minerals, like the interaction when carbon dioxide is pumped into basalt formations, or that alter the way seawater retains carbon dioxide, such as <a href="https://www.american.edu/sis/centers/carbon-removal/fact-sheet-ocean-alkalinization.cfm">increasing its alkalinity</a>, prevent carbon from escaping and are much more likely to keep it out of the atmosphere for hundreds or thousands of years.</p>
<h2>Ecological risks and benefits</h2>
<p>Another key question is what ecological benefits or risks accompany different ocean carbon dioxide removal approaches.</p>
<p>Research shows that some options, such as supporting mangrove forests, <a href="https://doi.org/10.1016/j.ecolecon.2020.106758">may promote biodiversity and benefit nearby human communities</a>.</p>
<p>However, other options could introduce novel risks. For example, growing and then sinking large amounts of kelp or algae <a href="https://doi.org/10.3389/fmars.2019.00107">could bring in invasive species</a>. Dissolving certain types of rock in the ocean could reduce ocean acidity. This would enhance the ocean’s ability to store carbon dioxide, but these rocks could also contain trace amounts of metals that could harm marine life, and these risks are <a href="https://doi.org/10.5194/bg-19-3683-2022">not well understood</a>.</p>
<figure class="align-center ">
<img alt="Satellite view of the coast showing swirls of phytoplankton" src="https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/483924/original/file-20220912-24-7r0v1n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Phytoplankton can grow explosively over a few days or weeks. Ocean fertilization is designed to supercharge that process to capture carbon dioxide, but it can have harmful affects for other marine life.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/features/Phytoplankton">Robert Simmon and Jesse Allen/NOAA/MODIS</a></span>
</figcaption>
</figure>
<p>Each process could also release some greenhouse gases, reducing its overall effectiveness.</p>
<h2>Interfering with nature is a social question</h2>
<p>The ocean affects everyone on the planet, but not everyone will have the same relationship to it or the same opportunities to have their opinions heard. </p>
<p>Much of the global population lives near the ocean, and some interventions <a href="https://doi.org/10.3389/fclim.2021.684063">might impinge on places that support jobs and communities</a>. For example, boosting algae growth could affect nearby wild fisheries or interfere with recreation. People and communities are going to evaluate these risks differently depending on how they are personally affected.</p>
<p>In addition, people’s trust in decision-makers often <a href="https://www.sciencedirect.com/science/article/pii/S0921800921000161">shapes their views of technologies</a>. Some ways of using the ocean to remove carbon, such as those close to the shore, could be governed locally. It’s less clear how decisions about the <a href="https://nap.nationalacademies.org/download/26278">high seas or deep ocean</a> would be made, since these areas are not under the jurisdiction of any one country or global governing body.</p>
<p>People’s perceptions will likely also be shaped by such factors as whether or not they see ocean carbon dioxide removal as <a href="https://doi.org/10.1016/j.gloenvcha.2013.06.002">interfering with nature or protecting it</a>. However, views of what is acceptable or not can change. As the impacts of climate change increase, <a href="https://doi.org/10.1111/cobi.13759">tolerance for some unconventional interventions seems to be growing</a>.</p>
<h2>It’s also an ethical question</h2>
<p>Ocean carbon dioxide removal also raises a variety of ethical questions that do not have straightforward answers.</p>
<p>For example, it forces people to consider the <a href="https://doi.org/10.5840/ijap201024221">relationship between humans and nonhumans</a>. Are humans obliged to intervene to reduce the impact on the climate, or ought we avoid ocean interventions? Do people have the right to purposefully intervene in the ocean or not? Are there specific obligations that humans ought to recognize when considering such options? </p>
<figure class="align-center ">
<img alt="People crouch down to plant mangroves." src="https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489449/original/file-20221012-18-7t7a2q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Volunteers plant mangrove saplings in the Philippines.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/filipino-volunteers-plant-mangrove-saplings-during-the-news-photo/73318400?phrase=philippines%20planting%20mangroves&adppopup=true">Romeo Gacad/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>Other ethical questions revolve around who makes decisions about ocean carbon dioxide removal and the consequences. For example, <a href="https://doi.org/10.1111/1758-5899.12921">who should be involved in decision-making</a> about the ocean? Could relying on ocean carbon dioxide removal <a href="https://doi.org/10.1016/j.crm.2021.100324">reduce societies’ commitment</a> to reducing emissions through other means, such as by reducing consumption, increasing efficiency and transforming energy systems?</p>
<h2>Who pays?</h2>
<p>Finally, ocean carbon dioxide removal could be very expensive. </p>
<p>For example, mining and then adding rocks to reduce the ocean’s acidity has been <a href="https://doi.org/10.1088/1748-9326/aaa9c4">estimated to cost</a> between US$60 and $200 per ton of carbon dioxide removed. To put that into context, the world produced <a href="https://www.iea.org/news/global-co2-emissions-rebounded-to-their-highest-level-in-history-in-2021">more than 36 billion metric tons</a> of carbon dioxide from energy alone in 2021.</p>
<p>Even macroalgae cultivation could be in the <a href="https://doi.org/10.1146/annurev-marine-032122-113850">tens of billions of dollars</a> if done at the scale likely necessary to have an impact.</p>
<p>These methods are more expensive than many actions that reduce emissions right now. For instance, using solar panels to avoid carbon emissions can range from saving money to a cost of $50 per ton of carbon dioxide, while actions like reducing methane emissions are <a href="https://www.iea.org/data-and-statistics/charts/ghg-abatement-costs-for-selected-measures-of-the-sustainable-recovery-plan">even less expensive</a>. But the harm from continued climate change has been estimated to be in the <a href="https://www.nature.com/articles/s41558-019-0444-6">hundreds of billions annually</a> in the United States alone.</p>
<p>These costs raise more questions. For example, how much debt is fair for future generations to carry, and how should the costs be distributed globally to fix a global problem? </p>
<p>Ocean carbon dioxide removal <a href="https://nap.nationalacademies.org/download/26278">could become a useful method</a> for keeping global warming in check, but it should not be seen as a silver bullet, especially since there isn’t an effective global system for making decisions about the ocean.</p>
<p><em>Sarah Cooley, a former research scientist at Woods Hole Oceanographic Institution and director of climate science at the Ocean Conservancy, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/188340/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Terre Satterfield receives funding from Pacific Institute for Climate Solutions
(F20-00333) to explore public attitudes toward OCDR</span></em></p><p class="fine-print"><em><span>Sonja Klinsky does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>From planting mangroves to dumping minerals in the ocean, there are lots of ideas for ocean carbon dioxide removal – and even more questions.Sonja Klinsky, Associate Professor and Senior Global Futures Scientist, Arizona State UniversityTerre Satterfield, Professor of Culture, Risk and the Environment, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1905342022-09-15T20:04:51Z2022-09-15T20:04:51ZEver heard of ocean forests? They’re larger than the Amazon and more productive than we thought<figure><img src="https://images.theconversation.com/files/484818/original/file-20220915-16-fk2cnk.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C4249%2C2809&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Amazon, Borneo, Congo, Daintree. We know the names of many of the world’s largest or most famous rainforests. And many of us know about the world’s largest span of forests, the boreal forests stretching from Russia to Canada.</p>
<p>But how many of us could name an underwater forest? Hidden underwater are huge kelp and seaweed forests, stretching much further than we previously realised. Few are even named. But their lush canopies are home to huge numbers of marine species. </p>
<p>Off the coastline of southern Africa lies the <a href="https://seachangeproject.com/great-african-seaforest/">Great African Seaforest</a>, while Australia boasts the <a href="https://theconversation.com/australias-other-reef-is-worth-more-than-10-billion-a-year-but-have-you-heard-of-it-45600">Great Southern Reef</a> around its southern reaches. There are many more vast but unnamed underwater forests all over the world. </p>
<p>Our new research has discovered just how <a href="https://onlinelibrary.wiley.com/doi/10.1111/geb.13515">extensive</a> and <a href="https://www.science.org/doi/full/10.1126/sciadv.abn2465">productive</a> they are. The world’s ocean forests, we found, cover an area twice the size of India. </p>
<p>These <a href="https://theconversation.com/marine-heatwaves-threaten-the-future-of-underwater-forests-37154">seaweed forests face threats from marine heatwaves and climate change</a>. But they may also hold part of the answer, with their ability to grow quickly and sequester carbon.</p>
<h2>What are ocean forests?</h2>
<p>Underwater forests are formed by seaweeds, which are types of algae. Like other plants, seaweeds grow by capturing the Sun’s energy and carbon dioxide through photosynthesis. The largest species grow tens of metres high, forming forest canopies that sway in a never-ending dance as swells move through. To swim through one is to see dappled light and shadow and a sense of constant movement.</p>
<p>Just like trees on land, these seaweeds offer habitat, food and shelter to a wide variety of marine organisms. Large species such as sea-bamboo and giant kelp have gas-filled structures that work like little balloons and help them create vast floating canopies. Other species relies on strong stems to stay upright and support their photosynthetic blades. Others again, like golden kelp on Australia’s Great Southern Reef, drape over seafloor. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=302&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=302&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=302&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=380&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=380&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484561/original/file-20220914-13-r8ii1k.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=380&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Only a few of the world’s most productive forests, such as the Great African Seaforest (GASF) and the Great Southern Reef (GSR), have been recognised and named.</span>
</figcaption>
</figure>
<h2>How extensive are these forests and how fast do they grow?</h2>
<p>Seaweeds have long been known to be among the fastest growing plants on the planet. But to date, it’s been very challenging to estimate how large an area their forests cover. </p>
<p>On land, you can now easily measure forests by satellite. Underwater, it’s much more complicated. Most satellites cannot take measurements at the depths where underwater forests are found. </p>
<p>To overcome this challenge, we relied on millions of underwater records from scientific literature, online repositories, local herbaria and <a href="https://marineforests.com/">citizen science initiatives</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484214/original/file-20220913-20-2ta0z6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ocean forests support biodiversity worldwide.</span>
<span class="attribution"><a class="source" href="http://facebook.com">Richard Shucksmith.</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>With this information, we modelled the global distribution of ocean forests, <a href="https://onlinelibrary.wiley.com/doi/10.1111/geb.13515">finding they cover</a> between 6 million and 7.2 million square kilometres. That’s larger than the Amazon.</p>
<p>Next, we assessed how productive these ocean forests are – that is, how much they grow. Once again, there were no unified global records. We had to go through hundreds of individual experimental studies from across the globe where seaweed growth rates had been measured by scuba divers. </p>
<p>We <a href="https://doi.org/10.1126/sciadv.abn2465">found</a> ocean forests are even more productive than many intensely farmed crops such as wheat, rice and corn. Productivity was highest in temperate regions, which are usually bathed in cool, nutrient-rich water. Every year, on average, ocean forests in these regions produce 2 to 11 times more biomass per area than these crops.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484814/original/file-20220915-26-cq7x60.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Biomass production of different crops and ocean forests (in grams of carbon per metre squared per year). Data derived from Pessarrodona et al. 2022 and the Food and Agriculture Organization.</span>
</figcaption>
</figure>
<h2>What do our findings mean for the challenges we face?</h2>
<p>These findings are encouraging. We could harness this immense productivity to help meet the world’s future food security. Seaweed farms can supplement food production on land and <a href="https://www.nature.com/articles/s41893-021-00773-9">boost sustainable development</a>. </p>
<p>These fast growth rates also mean seaweeds are hungry for carbon dioxide. As they grow, they pull large quantities of carbon from seawater and the atmosphere. Globally, ocean forests may <a href="https://onlinelibrary.wiley.com/doi/10.1111/geb.13515">take up as much carbon</a> as the Amazon.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-marine-heatwave-has-wiped-out-a-swathe-of-was-undersea-kelp-forest-62042">A marine heatwave has wiped out a swathe of WA's undersea kelp forest</a>
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<hr>
<p>This suggests they could play a role in mitigating climate change. However, not all that carbon may end up sequestered, as this requires seaweed carbon to be locked away from the atmosphere for relatively long periods of time. First estimates suggest that <a href="https://www.nature.com/articles/s41598-020-69258-7">a sizeable proportion</a> of seaweed could be sequestered in sediments or the deep sea. But exactly how much seaweed carbon ends up sequestered naturally is an area of intense research.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484259/original/file-20220913-18-4baduz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ocean forests take up vast quantities of carbon dioxide, and some of it may be sequestred for long periods of time.</span>
<span class="attribution"><span class="source">Helen Walne.</span></span>
</figcaption>
</figure>
<h2>Hard times for ocean forests</h2>
<p>Almost <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-ocean-heat-content#:%7E:text=More%20than%2090%20percent%20of,Ocean%20Heat%20Content%20product%20collection.">all of the extra heat</a> trapped by the 2,400 gigatonnes of greenhouse gases we have emitted so far has gone into our oceans. </p>
<p>This means ocean forests are facing very difficult conditions. Large expanses of ocean forests have recently disappeared off <a href="https://theconversation.com/a-marine-heatwave-has-wiped-out-a-swathe-of-was-undersea-kelp-forest-62042">Western Australia</a>, <a href="https://canadiangeographic.ca/articles/warming-water-is-killing-nova-scotias-kelp-forests/">eastern Canada</a> and <a href="https://www.nationalgeographic.com/science/article/california-critical-kelp-forests-disappearing-warming-world-can-they-be-saved">California</a>, resulting in the loss of habitat and carbon sequestration potential. </p>
<p>Conversely, as sea ice melts and water temperatures warm, some Arctic regions are expected to see expansion of <a href="https://theconversation.com/underwater-arctic-forests-are-expanding-with-rapid-warming-113016">their ocean forests</a>.</p>
<p>These overlooked forests play a crucial, largely unseen role off our coasts. The majority of the world’s underwater forests are unrecognised, unexplored and uncharted. </p>
<p>Without substantial efforts to improve our knowledge, it will not be possible to ensure their protection and conservation – let alone harness the full potential of the many opportunities they provide.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/can-selective-breeding-of-super-kelp-save-our-cold-water-reefs-from-hotter-seas-170271">Can selective breeding of 'super kelp' save our cold water reefs from hotter seas?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/190534/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Albert Pessarrodona Silvestre receives funding from the Australian Government Research Training Program, the Holsworth Wildlife Research Endowment. He is also affiliated with Conservation International. </span></em></p><p class="fine-print"><em><span>Karen Filbee-Dexter receives funding from the Australian Research Council, ArcticNet, the Norwegian Research Council, Schmidt Marine Technology Partners and Canopy Blue. Karen is affiliated with the Institute of Marine Research Norway and Laval University. </span></em></p><p class="fine-print"><em><span>Thomas Wernberg receives funding from The Australian Research Council, The Norwegian Research Council, The Schmidt Marine Technology Partners and Canopy Blue. Thomas is also affiliated with the Institute of Marine Research, Norway and Rosklid University, Denmark.</span></em></p>Our ocean forests of seaweed are enormous. But these quick-growing, life-supporting forests are already vanishing.Albert Pessarrodona Silvestre, Postdoctoral Research Fellow, The University of Western AustraliaKaren Filbee-Dexter, Research Fellow, School of Biological Sciences, The University of Western AustraliaThomas Wernberg, Professor, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1894812022-08-26T14:43:01Z2022-08-26T14:43:01ZExtensive algal blooms in England’s lakes: here’s why<figure><img src="https://images.theconversation.com/files/481306/original/file-20220826-1650-8ddjov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There have been reports of extensive blooms of blue-green algae on Lake Windermere this summer.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fishing-boat-on-green-water-aerial-1804469569">Sergey Muhlynin/Shutterstock</a></span></figcaption></figure><p>This year has seen growing public concern over the state of England’s largest lake, Windermere. Campaigners, local residents and visitors have <a href="https://www.theguardian.com/uk-news/2022/aug/24/it-stinks-lake-windermere-plagued-by-blue-green-algae-as-toxic-as-cobra-venom">reported</a> extensive blooms of blue-green algae at the site, with concern for its impact on health and ecology.</p>
<p>Somewhat misleadingly, blue-green algae are not actually algae. They are a type of bacteria, called cyanobacteria, which use sunlight to obtain energy and grow. There are many species of cyanobacteria. These can grow as single cells, too small to be seen with the naked eye, or in large clusters.</p>
<p>Cyanobacterial blooms are not new. They originated approximately <a href="https://news.mit.edu/2021/photosynthesis-evolution-origins-0928">3 billion years ago</a> and, through photosynthesis, they oxygenated the Earth’s atmosphere – helping to make other life possible. Cyanobacteria are found in a wide variety of freshwater habitats worldwide, including lakes such as Windermere.</p>
<p>The nutrients in wastewater, such as phosphorus, are critical for the formation of cyanobacterial blooms. The UK Centre for Ecology & Hydrology and the Freshwater Biological Association have carried out <a href="https://uk-scape.ceh.ac.uk/our-science/projects/cumbrian-lakes-monitoring-platform">long-term monitoring</a> of the lake. These data show that Windermere frequently experienced blooms in the past. </p>
<h2>What causes a cyanobacterial bloom?</h2>
<p>Blooms occur when cyanobacteria, usually present at low concentrations, multiply rapidly. This process is often invisible to lake users. However, during calm weather conditions, the cyanobacteria float to the surface and accumulate along the shoreline, where they are visible as “scums” or “slicks”. </p>
<p>High nutrient concentrations are needed to support large amounts of cyanobacteria. In Windermere, waste treatment sites combined with sewer overflows, run-off from nearby farmland and release from lake sediments can leak phosphorus into the lake.</p>
<figure class="align-center ">
<img alt="A sewer outflow discharging water into a river." src="https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sewer overflows can leak phosphorus into the lake, fuelling cyanobacterial blooms.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/discharge-untreated-water-into-natural-lake-1630211617">Slavik Rostovski/Shutterstock</a></span>
</figcaption>
</figure>
<p>Nitrogen concentrations can be important too. Some cyanobacteria can use dissolved nitrogen gas from the air to fuel their growth. This can give them a competitive advantage over other algae when nitrate concentrations are low.</p>
<p>Windermere is also <a href="https://www.ceh.ac.uk/news-and-media/blogs/lakes-hot-water-warming-trend-revealed-eight-decades-cumbrian-lake-temperature">warming</a> rapidly. The lake’s mean surface water temperature has risen by 1.7°C over the past 70 years, while warm summer conditions this year have contributed to <a href="https://seatemperature.info/windermere-water-temperature.html">above average</a> water temperatures for August. Fuelled by increasing nutrient concentrations, these warmer conditions have stimulated a rapid increase in cyanobacteria in Windermere.</p>
<p>As the climate continues to change, we can expect these weather conditions to become more frequent, and the risk of cyanobacterial blooms to increase.</p>
<h2>Are these blooms harmful?</h2>
<p>Cyanobacteria can produce potent toxins that can cause illness in humans and be fatal for animals.</p>
<p>However, not all blooms are toxic. This depends on both the species of cyanobacteria and the environmental conditions at the time. It is impossible to tell which blooms are toxic by sight and this can only be confirmed by laboratory analysis.</p>
<p>In addition to toxicity, the decomposition of dead cells from large blooms can reduce the oxygen content of the water. While this can reduce the habitat quality for aquatic wildlife, it can also <a href="https://ciglr.seas.umich.edu/spring-2021-e-newsletter/spotlight-dead-zone-sediment-p-release/">alter</a> the chemistry of the water and lake sediments. The reduction in oxygen concentration causes phosphorus that has been bound to iron in sediment to be released, which may stimulate further cyanobacterial growth.</p>
<h2>Can we reduce levels of harmful algae?</h2>
<p>To reduce the incidence of harmful blooms in lakes, the extreme weather conditions caused by climate change must be addressed. Mitigation of climate change can only come from coordinated international policy and action.</p>
<p>Locally, it is more feasible to manage the discharge of nutrients into lakes. However, both their source and pathway to the lake need to be established. </p>
<p>Further scientific evidence is required to determine what level of nutrient reduction is possible, and to guide measures to reduce the most significant sources. The Environment Agency has spent <a href="https://www.bbc.co.uk/news/uk-england-cumbria-62560942">more than £700,000</a> over the past decade on tackling cyanobacterial blooms.</p>
<p>Another challenge lies in forecasting how lakes will respond to differing future climate change scenarios. We cannot necessarily return lakes such as Windermere to a pristine state because the climate, human activities, land use in the surrounding area and species populations at the lake have all changed.</p>
<p>The sustainable management of our ecosystems for people and nature will require further research to forecast what the future of our freshwater ecosystems could be if we act now and, crucially, what will happen if we fail to do so.</p><img src="https://counter.theconversation.com/content/189481/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Thackeray receives no personal funding, but UKCEH long-term research at Windermere and other lakes is funded by Natural Environment Research Council award number NE/R016429/1 as part of the UK-SCAPE programme delivering National Capability.</span></em></p>Windermere has seen extensive algal blooms, attracting attention over its ecological consequences. But this is nothing new.Stephen Thackeray, Lake Ecologist and Modeller, UK Centre for Ecology & HydrologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1892952022-08-24T16:04:17Z2022-08-24T16:04:17ZA gourmet revival for St. Lawrence River marine algae<figure><img src="https://images.theconversation.com/files/480669/original/file-20220823-14-eai1ig.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Algae in the St. Lawrence River. The cold waters of Québec are conducive to their growth.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Seaweed has been part of the human diet for a long time. In Asia, its consumption is well established in culinary traditions. Think of the famous <a href="https://www.cbc.ca/life/food/miso-soup-with-root-vegetables-1.5047041">dashi</a>, the flavourful Japanese broth. </p>
<p>While less known in the West, <a href="https://www.sciencedirect.com/topics/food-science/edible-seaweed">algae is a traditional food</a> source in some coastal areas of Iceland, Ireland, <a href="https://docslib.org/doc/4408043/algae-as-food-and-food-supplements-in-europe">France, Denmark, Norway</a>, <a href="https://www.sciencedirect.com/science/article/abs/pii/S0268005X1630532X">the United States and Canada.</a></p>
<p>About fifty types of algae are consumed worldwide. The most common varieties available commercially include nori (used for sushi), dulse, sea beans or spaghetti, sea lettuce, wakame and Atlantic wakame, sea fern, and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0007996017300792">royal kombu (sea lasagna)</a>. </p>
<p>Many of these seaweeds are present in the St. Lawrence River.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
<hr>
<p>Their abundance, versatility and quality makes this resource a real asset for Québec. An asset that absolutely must be discovered.</p>
<p>I have been interested in the potential of seaweed and its development in food for a dozen years. My research activities focus on the study of St. Lawrence algae and their components. Recently, our research team at <a href="https://www.inaf.ulaval.ca/en/">Laval University’s Institute of Nutrition and Functional Foods</a> investigated the gastronomic potential of dashi from Québec seaweed.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476308/original/file-20220727-11-pn9cvu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An ocean of flavours.</span>
<span class="attribution"><span class="source">Manuel AÑÒ -- Explorateur par l’image</span></span>
</figcaption>
</figure>
<h2>Algae from the Saint Lawrence</h2>
<p>Large seaweed live in salt waters, on the <a href="https://www.sciencedirect.com/science/article/pii/S1319016409000462">coasts of oceans, seas and rivers</a>. They vary greatly in size, shape and colour. Marine algae are <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1529-8817.2012.01222.x">classified by their colour according to the pigments they contain</a>: green, brown, red. </p>
<p>Québec’s cold waters are favourable to their growth. Extremely low levels of pollution from industrial or urban sources in some places is an asset. Culturing activities can be <a href="https://link.springer.com/article/10.1007/s10811-016-0850-3">conducted without problems linked to the accumulation of heavy metals or pathogenic microorganisms</a> (which could cause disease).</p>
<p>With its 6,000 km of coastline, spread over the Gaspé, North Shore and Lower St. Lawrence regions, the maritime estuary and the Gulf are home to 346 species of algae. <a href="http://exploramer.qc.ca/en/what-is-smarter-seafood/">Fifteen of these are certified “Fourchette bleue”</a> or Blue Fork 2022, a Québec certification that aims to introduce new marine products to the public while also supporting sustainable use of the resource.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476096/original/file-20220726-22290-9s8vat.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Harvesting Alaria esculenta (Atlantic Wakame).</span>
<span class="attribution"><span class="source">Credit Merinov</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Seaweed is available in different forms, either fresh, dried, blanched, frozen, in flakes or spices, and sometimes already processed (ready-to-eat like pesto, relish, tartar mixture). The integration of St. Lawrence algae into common products such as salad dressings, bread, <a href="https://buvez.quebec/en/degustations/gose-aux-algues/">beer</a>, <a href="https://couleurchocolat.panierdachat.app/en/product/dark-chocolate-raspberries-and-nori-seaweed-bar">chocolate</a>, <a href="https://ifst.onlinelibrary.wiley.com/doi/full/10.1111/ijfs.13681">cheese</a>, yogurt, salt and spices, for example in the Gaspé or the Lower St. Lawrence, is becoming increasingly popular.</p>
<p>In restaurants, <a href="https://www.bonappetit.com/test-kitchen/ingredients/article/seaweed-primer">chefs</a> are also mastering Québec’s seaweed: it encourages them to revisit traditional recipes and break new culinary grounds.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vYHYaY-eN-g?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Fished here, eaten here. Québec Ministry of Agriculture, Fisheries and Food.</span></figcaption>
</figure>
<h2>The health benefits of seaweed</h2>
<p>These sea vegetables contain fiber, protein, vitamins and minerals, which make them attractive from a nutritional point of view and as prevention against certain diseases, such as <a href="https://cdnsciencepub.com/doi/abs/10.1139/h11-115">obesity</a>. There is <a href="https://pubmed.ncbi.nlm.nih.gov/34597023/">therefore a growing interest in including</a> them into the diet.</p>
<p>In addition to the desire to eat healthily, the locavore movement (which raises awareness of the value of sustainable local resources), the promotion of local products, gourmet and culinary innovation are also <a href="https://www.foodinspiration.com/us/what-the-world-needs-now-a-sustainable-seaweed-revolution/">inspiring the introduction of seaweed in our plates</a>. The most common are used in sushi, salads, soups, even in desserts or as seasoning and flavour enhancers.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476097/original/file-20220726-33182-tn8vvn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Trout fillet steamed with seaweed and sea lettuce sauce.</span>
<span class="attribution"><span class="source">INAF</span></span>
</figcaption>
</figure>
<h2>The taste of seaweed</h2>
<p><a href="https://link.springer.com/article/10.1007/s10811-022-02731-0">Phycogastronomy</a> (scientific gourmet seaweed cuisine) has now emerged to <a href="https://link.springer.com/article/10.1007/s10811-022-02731-0">develop a collaborative approach between researchers and professional chefs</a>. Its goal is to support culinary creations based on a scientific basis, and to encourage algae eating among the general public.</p>
<p>Consumer acceptance of these new algae products, however, depends on their organoleptic properties, in particular aroma, taste and a combination of the two — flavour. </p>
<p>Seaweed has very specific flavour produced by <a href="https://www.sciencedirect.com/science/article/abs/pii/S0268005X1630532X">minerals, sugars and many volatile organic compounds</a>. This taste is closely related to the <a href="https://en.wikipedia.org/wiki/Umami">umami flavour</a>, which is referred to as the fifth flavour in addition to the other four known tastes (acid, sweet, salty, bitter).</p>
<p>Amino acid compounds, such as glutamate and aspartate as well as substances derived from nucleic acids dissolved in the cells of some algae, especially nori, <a href="https://www.researchgate.net/publication/257883487_Seaweeds_for_umami_flavour_in_the_New_Nordic_Cuisine">are a source of umami flavour</a>.</p>
<p>Glutamate, an amino acid naturally found in food, is a flavour enhancer in cooking. It is present in parmesan cheese, ripe tomatoes, and also in fish and soy sauce. Some algae species, especially kombu and several other brown algae, have a strong iodine taste. Along with iodine, potassium and sodium also provide a marine taste. Sweet kelp (royal kombu) contains a sugar, mannitol, which gives it its characteristic mild and sweet taste.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476313/original/file-20220727-1306-adlfsb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cultivation of sweet kelp (Saccharina latissima).</span>
<span class="attribution"><span class="source">Élizabeth Varennes</span></span>
</figcaption>
</figure>
<p>Algae can also release odours or reveal flavours associated with volatile organic compounds. There are common descriptions of seaweed aromas (marine, sulfur, vegetable, woody, spicy), which are associated with multiple compounds. As sensory characteristics are linked to consumer acceptance of a food, <a href="https://pubs.acs.org/doi/abs/10.1021/acs.jafc.1c04409">many studies are exploring the flavours of algae</a>, and the impact of their inclusion in a diet.</p>
<h2>Dashi made with Québec seaweed</h2>
<p>One of the most famous seaweed dishes is a Japanese specialty called dashi, which is <a href="https://www.sciencedirect.com/science/article/abs/pii/S0268005X1630532X">a soup broth made from Japanese kombu seaweed</a>. </p>
<p>Dashi is a very good representative of the umami taste as its cooking process results in the extraction of a large amount of glutamate. In our research to produce a Québec dashi, we selected two seaweeds because of their <a href="https://link.springer.com/article/10.1007/s10811-019-01846-1">history of consumption</a>, availability and culinary interest: red dulse (sea bacon) and brown royal kombu (sea lasagna).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476310/original/file-20220727-19-l8rbm0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dulse (Palmaria palmata).</span>
<span class="attribution"><span class="source">Credit Merinov</span></span>
</figcaption>
</figure>
<p>Broth production was monitored at different temperatures and cooking times. It was analyzed for its chemical composition (minerals, proteins and carbohydrates) as well as for its sensory physico-chemical sensory characteristics (color, texture, umami compounds and volatile organic compounds).</p>
<p>Results showed that algae nutrients were preserved in the broths. Those made from sea lasagna were more colourful, richer in minerals, and had salty, marine and vegetable flavours. </p>
<p>The dulse broths were thicker with a higher amount of carbohydrates, and had sweet, fruity, herbaceous aromas, and an interesting umami flavour potential.</p>
<p>Dulse is therefore the <a href="https://www.semanticscholar.org/paper/Impact-of-temperature-and-cooking-time-on-the-and-Lafeuille-Francezon/79e2fb5c61649ff3dd4dfae0afb51f34e98de2cf">seaweed that produced a dashi that was more diverse in aromas and rich in umami</a> flavours. </p>
<p>Consumers are intrigued by the idea of eating St. Lawrence seaweed and are curious to learn more about its origin. Seaweed can thus earn a place on menus, and in the future could have an even bigger presence in our daily meals.</p><img src="https://counter.theconversation.com/content/189295/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lucie Beaulieu is the director of the interest group on marine products and co-products of the Institute of Nutrition and Functional Foods (INAF) and director of the theme - Resources and Sustainable Maritime Economy of the Réseau Québec Maritime (RQM). She has received funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), the Fonds de recherche du Québec - Nature et technologie (FRQNT), the Consortium de recherche et innovations en bioprocédés industriels au Québec (CRIBIQ), the Consortium de Recherche, en Innovation et en Transformation Alimentaire (RITA), MITACS, the North Sentinel program the RFI Food for tomorrow - Cap Aliments program, the Institut France-Québec maritime (IFQM), several provincial and federal ministries (Ministère de l'Agriculture, des Pêcheries et de l'Alimentation, Ministère de l'Économie et de l'Innovation, Ministère des Relations Internationales, Fonds des Pêches du Québec, Conseil National de Recherche du Canada)
</span></em></p>The abundance, versatility and quality of seaweed from the St. Lawrence makes this resource a real asset for Québec. We must now integrate it into our kitchens.Lucie Beaulieu, Professeure en Sciences des aliments, Université LavalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1862862022-07-18T12:26:45Z2022-07-18T12:26:45ZTo reduce harmful algal blooms and dead zones, the US needs a national strategy for regulating farm pollution<figure><img src="https://images.theconversation.com/files/474164/original/file-20220714-32338-xz3rmp.jpeg?ixlib=rb-1.1.0&rect=52%2C0%2C8713%2C5835&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Satellite photo of an algal bloom in western Lake Erie, July 28, 2015.</span> <span class="attribution"><a class="source" href="https://eoimages.gsfc.nasa.gov/images/imagerecords/86000/86327/erie_oli_2015209_lrg.jpg">NASA Earth Observatory</a></span></figcaption></figure><p>Midsummer is the time for forecasts of the size of this year’s “dead zones” and algal blooms in major lakes and bays. Will the <a href="https://www.nola.com/news/environment/article_bfc1ba32-e2ac-11ec-9909-5fd0e4edb56b.html">Gulf of Mexico dead zone</a> be the size of New Jersey, or only as big as Connecticut? Will Lake Erie’s bloom blossom to a <a href="https://www.toledoblade.com/local/2014/08/03/Water-crisis-grips-area/stories/20140803090">human health crisis</a>, or just devastate the <a href="https://www.ectinc.com/projects/economic-benefits-costs-of-reducing-harmful-algal-blooms-in-lake-erie/">coastal economy</a>? </p>
<p>We are scientists who each have spent almost 50 years figuring out <a href="https://scholar.google.com/citations?user=ARkaE6cAAAAJ&hl=en">what causes dead zones</a> and what it will take to resuscitate them and reduce <a href="https://scholar.google.com/citations?user=-K4wV5QAAAAJ&hl=en">risks of toxic blooms of algae</a>. Researchers can <a href="https://theconversation.com/forecasting-dead-zones-and-toxic-algae-in-us-waterways-a-bad-year-for-lake-erie-43747">forecast</a> these phenomena quite well and have calculated the nitrogen and phosphorus pollution cuts needed to reduce them. </p>
<p>These targets are now written into formal government commitments to clean up <a href="https://doi.org/10.1016/j.jglr.2016.09.007">Lake Erie</a>, the <a href="https://doi.org/10.1073/pnas.1705293114">Gulf</a> and the <a href="https://doi.org/10.1002/eap.2384">Chesapeake Bay</a>. Farmers and land owners nationwide received US$30 billion to support conservation, including practices designed to reduce water pollution, from <a href="https://www.ewg.org/news-insights/news-release/new-ewg-database-details-30-billion-spent-us-farm-conservation-programs">2005 to 2015</a>, and are scheduled to receive $60 billion more between <a href="https://crsreports.congress.gov/product/pdf/IF/IF12024#:%7E:text=Spending%20for%20agricultural%20conservation%20programs,are%20reauthorized%20with%20no%20changes.">2019 and 2028</a>. </p>
<p>But these efforts have fallen short, mainly because controls on nutrient pollution from agriculture are <a href="https://doi.org/10.3389/fmars.2019.00123">weak and ineffective</a>. In our view, there is no shortage of solutions to this problem. What’s needed is technological innovation and stronger political will. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing a zone with low oxygen values along the Louisiana coast." src="https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=299&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=299&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=299&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=376&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=376&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=376&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Gulf of Mexico hypoxic (dead) zone in 2021, which measured 6,334 square miles (16,400 square kilometers). Lower values represent less dissolved oxygen in the water.</span>
<span class="attribution"><a class="source" href="https://nrtwq.usgs.gov/nwqn/Sites/GULF_PRELIM/cruise2021-Final_2021_map_KM.jpg">Louisiana Universities Marine Consortium</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Problems return to Lake Erie</h2>
<p>State and federal agencies have known since the 1970s that overloading lakes and bays with nutrients generates huge blooms of algae. When the algae die and decompose, they deplete oxygen in the water, creating dead zones that can’t support aquatic life. But in each of these “big three” water bodies, efforts to curb nutrient pollution have been slow and halting. </p>
<p>The U.S., Canada and cities around Lake Erie started working to reduce phosphorus pollution in the lake from domestic and industrial wastes <a href="https://clevelandhistorical.org/items/show/58?tour=12&index=11">in 1972</a>. Water quality quickly improved, dead zones shrank and harmful algal blooms became less frequent. </p>
<p>But the scourges of <a href="https://doi.org/10.1016/j.jglr.2014.02.004">low-oxygen waters and sometimes-toxic algae</a> reappeared in the mid-1990s. This time, the source was mostly runoff from farm soils saturated with phosphorus from repeated applications of fertilizer and manure. Climate change made matters worse: Warmer waters hold less oxygen and <a href="https://blog.nature.org/science/2014/08/27/understanding-the-lake-erie-algal-bloom-toledo-water-shutdown/">cause faster growth of algae</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bar chart showing phosphorus entering Lake Erie 1967-2001." src="https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=407&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=407&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=407&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Phosphorus loads to Lake Erie, 1967-2001. Nonpoint sources are wide areas without a distinct discharge point, such as farm fields.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1016/j.jglr.2014.02.004">Scavia et al., 2014</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Slow progress in the Chesapeake Bay</h2>
<p>Nitrogen and phosphorus reach the Chesapeake Bay from sources including wastewater treatment plants; air pollution emitters, such as factories and cars; and runoff from urban, suburban and agricultural lands. In 1987 the federal government and states around the bay agreed to reduce these flows by <a href="https://www.epa.gov/chesapeake-bay-tmdl/chesapeake-bay-agreements">40% by the year 2000</a> to restore water quality. But this effort relied on voluntary action and failed to make much progress. </p>
<p>In 2010 the states and the U.S. Environmental Protection Agency entered <a href="https://www.epa.gov/chesapeake-bay-tmdl/chesapeake-bay-tmdl-document">a legally binding commitment</a>, to reduce pollutant loads below prescribed maximum levels needed to restore water quality. If the states make inadequate progress, the EPA can limit or rescind their permitting authority, and the states may lose federal funding. </p>
<p>Nitrogen and phosphorus pollution has been <a href="https://www.chesapeakeprogress.com/clean-water/2017-watershed-implementation-plans">reduced</a> primarily by tightening permit requirements and upgrading wastewater treatment plants. Air pollution controls for power plants and vehicles have also reduced nitrogen reaching the bay. Water quality has improved, and the yearly dead zone has <a href="https://doi.org/10.1016/j.scitotenv.2021.152722">shrunk modestly</a>. </p>
<p>But with the commitment’s 2025 deadline nearing, nitrogen loads have been reduced by less then 50% of the targeted amounts, phosphorus by <a href="https://www.chesapeakebay.net/news/pressrelease/bay_program_model_shows_decline_in_nutrient_sediment_pollution_entering_the">less then 64%</a>. Most of the remaining pollution comes from <a href="https://doi.org/10.1002/jeq2.20101">farm runoff and urban stormwater</a>.
Intensifying agriculture in rural areas and sprawl in urban areas are counteracting other cleanup efforts. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Og4gYUR_m94?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Cleaning up water bodies with large watersheds, like the Chesapeake Bay (64,000 square miles/165,000 square kilometers, involves many states and thousands of pollution sources.</span></figcaption>
</figure>
<h2>Failure in the Gulf of Mexico</h2>
<p>The Gulf of Mexico dead zone forms every year during the summer, fueled by nutrients washing down the Mississippi River from Midwest farms. It <a href="https://www.noaa.gov/news-release/larger-than-average-gulf-of-mexico-dead-zone-measured">typically covers at least 6,000 square miles</a>, sometimes expanding up to 9,000 square miles (23,000 square kilometers), and affects an area very rich in fisheries. </p>
<p>In 2001, the EPA and 12 Mississippi River basin states agreed to take action to reduce the Gulf dead zone by two-thirds by 2015. Researchers estimated that this would require <a href="https://www.epa.gov/sites/default/files/2015-03/documents/2008_1_31_msbasin_sab_report_2007.pdf">reducing nitrogen loads reaching the Gulf by about 45%</a>, mostly from the Corn Belt. </p>
<p>Now that deadline has been <a href="https://www.epa.gov/sites/default/files/2015-10/documents/htf_report_to_congress_final_-_10.1.15.pdf">extended to 2035</a>. Nitrogen and phosphorus loadings at the mouth of the Mississippi River <a href="https://nrtwq.usgs.gov/nwqn/#/GULF">haven’t budged in 30 years</a>, so actions taken to date have <a href="https://www.epa.gov/ms-htf/history-hypoxia-task-force">failed to shrink the Gulf dead zone</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bar chart showing measurements of the Gulf of Mexico dead zone since 1985." src="https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Since 2017 the Gulf of Mexico dead zone has covered an average of 5,380 square miles (14,000 square kilometers), which is 2.8 times larger than the 2035 target set by a federal task force.</span>
<span class="attribution"><a class="source" href="https://www.noaa.gov/news-release/larger-than-average-gulf-of-mexico-dead-zone-measured">LUMCON/NOAA</a></span>
</figcaption>
</figure>
<h2>Overwhelmed by agriculture</h2>
<p>In 2020, the EPA and Ohio <a href="https://epa.ohio.gov/static/Portals/35/tmdl/MaumeeNutrient/Maumee-Nutrient-TMDL-062022.pdf">adopted an agreement</a> similar to that for the Chesapeake to reduce phosphorus pollution below a prescribed maximum load from the Maumee River watershed at the western end of Lake Erie, where algal blooms occur most often. To date, Mississippi River basin states and even the EPA have <a href="https://doi.org/10.15779/Z38T727G2Q">opposed similarly mandating maximum pollution loads</a> to reduce the Gulf of Mexico dead zone. </p>
<p>Despite substantial government subsidies to implement various agricultural management practices, nitrogen and phosphorus pollution in streams in <a href="https://doi.org/10.1371/journal.pone.0195930">Iowa</a> and <a href="https://www2.illinois.gov/epa/topics/water-quality/watershed-management/excess-nutrients/Documents/NLRS-2021-Biennial-Report-FINAL.pdf">Illinois</a> has actually increased over the 1980-1996 baseline of the Gulf agreement. </p>
<p>Even with increasing crop yields and more efficient use of fertilizer, the expansion and intensification of agriculture in the Midwest has overwhelmed any water quality gains. One driver is ethanol production, which has increased <a href="https://www.eia.gov/todayinenergy/detail.php?id=36892">fortyfold</a> since the Gulf action plan was adopted in 2001. Today, over 40% of corn grown in the U.S. is <a href="https://www.ers.usda.gov/topics/crops/corn-and-other-feedgrains/feedgrains-sector-at-a-glance/">used for ethanol</a>, mostly in the Midwest, while most of the rest is used to feed animals. </p>
<p>In all three regions, the growth of large-scale livestock farms – <a href="https://www.vox.com/the-highlight/22344953/iowa-select-jeff-hansen-pork-farming">hogs in the Midwest</a>, <a href="https://www.delmarvanow.com/story/news/2021/10/29/84-poultry-operations-raised-water-pollution-concerns-yet-few-fined-report-environmental-watchdog/6180639001/">poultry around the Chesapeake Bay</a> – is also contributing to nutrient pollution. <a href="https://doi.org/10.1016/j.resconrec.2020.105065">Improper management of animal waste</a> adds to nitrogen and phosphorus loads in soils and local waters. </p>
<p>Studies show that agriculture contributes <a href="http://scavia.seas.umich.edu/wp-content/uploads/2018/02/Final-Report-Update-20160415.pdf">85% of Lake Erie’s Maumee River phosphorus load</a>, <a href="https://pubs.usgs.gov/circ/1486/cir1486.pdf">65% of the Chesapeake Bay’s nitrogen load</a> and 73.2% of the nitrogen load and 56% of the phosphorus load to the <a href="https://doi.org/10.1111/1752-1688.12905">Gulf of Mexico</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1223304943265648642"}"></div></p>
<h2>Incentives aren’t working</h2>
<p>We believe the evidence is clear that the largely voluntary approaches taken to date, with technical assistance and substantial public financing, are not working. </p>
<p>Economists have called for a <a href="https://doi.org/10.1111/1752-1688.13010">fundamental shift in policies controlling agricultural pollution</a>. Instead of offering polluters subsidies to clean up their operations, these experts argue, the strategy should be to pay farmers for performance, based on environmental outcomes that can be measured <a href="https://doi.org/10.13031/trans.12379">or predicted</a> at appropriate scales and specific places. </p>
<p>Under this approach, government would set limits on the amount of nutrients that can be lost to the environment, and farmers would choose how to meet them, based on what kinds of action work best for their specific soils and climate. For example, <a href="https://doi.org/10.1038/s41586-020-03042-5">restoring wetlands</a> within the watershed could help to capture nutrients that unavoidably wash off of farmlands. </p>
<p>The ongoing shift to electric vehicles offers an opportunity to grow far less grain for ethanol, which <a href="https://theconversation.com/the-us-biofuel-mandate-helps-farmers-but-does-little-for-energy-security-and-harms-the-environment-168459">doesn’t even help the climate</a>. And in the long run, developing <a href="https://www.scientificamerican.com/article/heres-how-much-food-contributes-to-climate-change/">efficient, plant-based food systems</a> would both reduce nutrient pollution and limit climate change. </p>
<p>In June 2022, the Government Accountability Office concluded that federal agencies charged with preventing and controlling harmful algal blooms and dead zones under a <a href="https://www.govinfo.gov/content/pkg/PLAW-105publ383/pdf/PLAW-105publ383.pdf">1998 law</a> have <a href="https://www.gao.gov/assets/gao-22-104449.pdf">failed to establish a national program</a> to address these issues. Fifty years after the federal Clean Water Act was enacted, we believe such a program is long overdue.</p><img src="https://counter.theconversation.com/content/186286/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Donald Boesch does not work for, consult, own shares in, or receive funding from any company or organization that would benefit from this article. He currently receives no external funding, but previously received funding from the National Science Foundation, Environmental Protection Agency, National Oceanic and Atmospheric Administration, and the Walton Family Foundation.</span></em></p><p class="fine-print"><em><span>Donald Scavia does not work for, consult, own shares in, or receive funding from any company or organization that would benefit from this article. He has received research funding from the National Science Foundation, Environmental Protection Agency, National Oceanic and Atmospheric Administration, and the Erb Family Foundation.</span></em></p>Nutrient pollution fouls lakes and bays with algae, killing fish and threatening public health. Progress curbing it has been slow, mainly because of farm pollution.Donald Boesch, Professor of Marine Science, University of Maryland Center for Environmental ScienceDonald Scavia, Professor Emeritus of Environment and Sustainability, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1848282022-07-14T12:34:04Z2022-07-14T12:34:04ZTo search for alien life, astronomers will look for clues in the atmospheres of distant planets – and the James Webb Space Telescope just proved it’s possible to do so<figure><img src="https://images.theconversation.com/files/473980/original/file-20220713-20-g1f04j.png?ixlib=rb-1.1.0&rect=34%2C116%2C691%2C572&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">TRAPPIST-1e is a rocky exoplanet in the habitable zone of a star 40 light-years from Earth and may have water and clouds, as depicted in this artist's impression.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:TRAPPIST-1e_artist_impression_2018.png#/media/File:TRAPPIST-1e_artist_impression_2018.png">NASA/JPL-Caltech/Wikimedia Commons</a></span></figcaption></figure><p>The ingredients for life are <a href="https://doi.org/10.1073/pnas.98.3.805">spread throughout the universe</a>. While Earth is the only known place in the universe with life, detecting life beyond Earth is a <a href="https://www.planetary.org/articles/the-2020-astrophysics-decadal-survey-guide">major goal</a> of <a href="https://www.planetary.org/space-policy/what-is-the-decadal-survey">modern astronomy</a> and <a href="https://www.planetary.org/space-policy/what-is-the-decadal-survey">planetary science</a>.</p>
<p>We are two scientists who study <a href="https://scholar.google.com/citations?user=2SCIYjIAAAAJ&hl=en&oi=ao">exoplanets</a> and <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en&oi=ao">astrobiology</a>. Thanks in large part to next-generation telescopes like James Webb, researchers like us will soon be able to measure the chemical makeup of atmospheres of planets around other stars. The hope is that one or more of these planets will have a chemical signature of life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing green bands around stars." src="https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473981/original/file-20220713-24-ei1562.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There are many known exoplanets in habitable zones – orbits not too close to a star that the water boils off but not so far that the planet is frozen solid – as marked in green for both the solar system and Kepler-186 star system with its planets labeled b, c, d, e and f.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Kepler186f-ComparisonGraphic-20140417_improved.jpg#/media/File:Kepler186f-ComparisonGraphic-20140417_improved.jpg">NASA Ames/SETI Institute/JPL-Caltech/Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>Habitable exoplanets</h2>
<p>Life <a href="https://doi.org/10.1073/pnas.1816535115">might exist in the solar system</a> where there is liquid water – like the subsurface aquifers on Mars or in the oceans of Jupiter’s moon Europa. However, searching for life in these places is incredibly difficult, as they are hard to reach and detecting life would require sending a probe to return physical samples.</p>
<p>Many astronomers believe there’s a <a href="https://exoplanets.nasa.gov/news/1675/life-in-the-universe-what-are-the-odds/">good chance that life exists on planets orbiting other stars</a>, and it’s possible that’s where <a href="https://doi.org/10.1016/j.actaastro.2022.03.019">life will first be found</a>.</p>
<p>Theoretical calculations suggest that there are around <a href="https://www.technologyreview.com/2020/11/06/1011784/half-milky-way-sun-like-stars-home-earth-like-planets-kepler-gaia-habitable-life/">300 million potentially habitable planets</a> in the Milky Way galaxy alone and <a href="https://doi.org/10.3847/1538-3881/abc418">several habitable Earth-sized planets</a> within only 30 light-years of Earth – essentially humanity’s galactic neighbors. So far, astronomers have <a href="https://exoplanets.nasa.gov/">discovered over 5,000 exoplanets</a>, including hundreds of potentially habitable ones, using <a href="https://sci.esa.int/web/exoplanets/-/60655-detection-methods">indirect methods</a> that measure how a planet affects its nearby star. These measurements can give astronomers information on the mass and size of an exoplanet, but not much else.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing two lines each with two peaks in the blue and red wavelengths." src="https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473983/original/file-20220713-17654-sd7qoy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Every material absorbs certain wavelengths of light, as shown in this diagram depicting the wavelengths of light absorbed most easily by different types of chlorophyll.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Chlorophyll_ab_spectra-en.svg#/media/File:Chlorophyll_ab_spectra-en.svg">Daniele Pugliesi/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Looking for biosignatures</h2>
<p>To detect life on a distant planet, astrobiologists will study starlight that has <a href="https://doi.org/10.1089/ast.2017.1729">interacted with a planet’s surface or atmosphere</a>. If the atmosphere or surface was transformed by life, the light may carry a clue, called a “biosignature.”</p>
<p>For the first half of its existence, Earth sported an atmosphere without oxygen, even though it hosted simple, single-celled life. Earth’s biosignature was very faint during this early era. That changed abruptly <a href="https://asm.org/Articles/2022/February/The-Great-Oxidation-Event-How-Cyanobacteria-Change">2.4 billion years ago</a> when a new family of algae evolved. The algae used a process of photosynthesis that produces free oxygen – oxygen that isn’t chemically bonded to any other element. From that time on, Earth’s oxygen-filled atmosphere has left a strong and easily detectable biosignature on light that passes through it.</p>
<p>When light bounces off the surface of a material or passes through a gas, certain wavelengths of the light are more likely to remain trapped in the gas or material’s surface than others. This selective trapping of wavelengths of light is why objects are different colors. Leaves are green because chlorophyll is particularly good at absorbing light in the red and blue wavelengths. As light hits a leaf, the red and blue wavelengths are absorbed, leaving mostly green light to bounce back into your eyes.</p>
<p>The pattern of missing light is determined by the specific composition of the material the light interacts with. Because of this, astronomers can learn something about the composition of an exoplanet’s atmosphere or surface by, in essence, measuring the specific color of light that comes from a planet. </p>
<p>This method can be used to recognize the presence of certain atmospheric gases that are associated with life – such as oxygen or methane – because these gasses leave very specific signatures in light. It could also be used to detect peculiar colors on the surface of a planet. On Earth, for example, the chlorophyll and other pigments plants and algae use for photosynthesis capture specific wavelengths of light. These pigments <a href="https://doi.org/10.1073/pnas.1304213111">produce characteristic colors</a> that can be detected by using a sensitive infrared camera. If you were to see this color reflecting off the surface of a distant planet, it would potentially signify the presence of chlorophyll.</p>
<h2>Telescopes in space and on Earth</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A giant gold mirror in a lab." src="https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=899&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=899&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=899&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473985/original/file-20220713-17654-d5rtyi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The James Webb Space Telescope is the first telescope able to detect chemical signatures from exoplanets, but it is limited in its capabilities.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:JWST_Full_Mirror.jpg#/media/File:JWST_Full_Mirror.jpg">NASA/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>It takes an incredibly powerful telescope to detect these subtle changes to the light coming from a potentially habitable exoplanet. For now, the only telescope capable of such a feat is the new <a href="http://jwst.nasa.gov/">James Webb Space Telescope</a>. As it <a href="https://blogs.nasa.gov/webb/2022/07/11/nasas-webb-telescope-is-now-fully-ready-for-science/">began science operations</a> in July 2022, James Webb took a reading of the spectrum of the <a href="https://www.nytimes.com/2022/07/12/science/wasp-96b-exoplanet-webb-telescope.html">gas giant exoplanet WASP-96b</a>. The spectrum showed the presence of water and clouds, but a planet as large and hot as WASP-96b is unlikely to host life.</p>
<p>However, this early data shows that James Webb is capable of detecting faint chemical signatures in light coming from exoplanets. In the coming months, Webb is set to turn its mirrors toward <a href="https://www.space.com/42512-trappist-1-planet-could-host-life.html">TRAPPIST-1e</a>, a potentially habitable Earth-sized planet a mere 39 light-years from Earth.</p>
<p>Webb can look for biosignatures by studying planets as they pass in front of their host stars and capturing <a href="https://www.physics.uu.se/research/astronomy-and-space-physics/research/planets/exoplanet-atmospheres/">starlight that filters through the planet’s atmosphere</a>. But Webb was not designed to search for life, so the telescope is only able to scrutinize a few of the nearest potentially habitable worlds. It also can only detect changes to <a href="https://doi.org/10.3847/1538-3881/ab21e0">atmospheric levels of carbon dioxide, methane and water vapor</a>. While certain combinations of these gasses <a href="https://doi.org/10.1038/s41550-021-01579-7">may suggest life</a>, Webb is not able to detect the presence of unbonded oxygen, which is the strongest signal for life.</p>
<p>Leading concepts for future, even more powerful, space telescopes include plans to block the bright light of a planet’s host star to reveal starlight reflected back from the planet. This idea is similar to using your hand to block sunlight to better see something in the distance. Future space telescopes could use small, internal masks or large, external, umbrella-like spacecraft to do this. Once the starlight is blocked, it becomes much easier to study light bouncing off a planet.</p>
<p>There are also three enormous, ground-based telescopes currently under construction that will be able to search for biosignatures: the <a href="http://gmto.org/">Giant Magellen Telescope</a>, the <a href="https://www.tmt.org/">Thirty Meter Telescope</a> and the <a href="https://www.eso.org/sci/facilities/eelt/">European Extremely Large Telescope</a>. Each is far more powerful than existing telescopes on Earth, and despite the handicap of Earth’s atmosphere distorting starlight, these telescopes might be able to probe the atmospheres of the closest worlds for oxygen.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cow and its calf standing in a field." src="https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=406&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=406&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=406&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473982/original/file-20220713-12-4xssot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Animals, including cows, produce methane, but so do many geologic processes.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Cows_eating_grass_(42882305160).jpg#/media/File:Cows_eating_grass_(42882305160).jpg">Jernej Furman/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Is it biology or geology?</h2>
<p>Even using the most powerful telescopes of the coming decades, astrobiologists will only be able to detect strong biosignatures produced by worlds that have been completely transformed by life.</p>
<p>Unfortunately, most gases released by terrestrial life can also be produced by nonbiological processes – cows and volcanoes both release methane. Photosynthesis produces oxygen, but sunlight does, too, when it splits water molecules into oxygen and hydrogen. There is a <a href="https://doi.org/10.1089/ast.2017.1727">good chance astronomers will detect some false positives</a> when looking for distant life. To help rule out false positives, astronomers will need to understand a planet of interest well enough to understand whether its <a href="https://doi.org/10.1089/ast.2017.1737">geologic or atmospheric processes could mimic a biosignature</a>. </p>
<p>The next generation of exoplanet studies has the potential to pass the bar of the <a href="https://quoteinvestigator.com/2021/12/05/extraordinary/">extraordinary evidence</a> needed to prove the existence of life. The first data release from the James Webb Space Telescope gives us a sense of the exciting progress that’s coming soon.</p><img src="https://counter.theconversation.com/content/184828/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Daniel Apai receives funding from NASA and the Gordon and Betty Moore Foundation.</span></em></p>Life on Earth has dramatically changed the chemistry of the planet. Astronomers will measure light that bounces off distant planets to look for similar clues that they host life.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaDaniel Apai, Professor of Astronomy and Planetary Sciences, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1810372022-05-19T12:23:07Z2022-05-19T12:23:07ZRestoring the Great Lakes: After 50 years of US-Canada joint efforts, some success and lots of unfinished business<figure><img src="https://images.theconversation.com/files/464009/original/file-20220518-11-qy3i71.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4000%2C2311&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Children participate in a water fight in Lake Ontario in Mississauga, Ontario, during a heat wave on June 5, 2021. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/children-have-a-water-fight-at-lake-ontario-in-mississauga-news-photo/1233295324">Zou Zheng/Xinhua via Getty Images</a></span></figcaption></figure><p>The Great Lakes cover <a href="https://theconversation.com/the-impulse-to-garden-in-hard-times-has-deep-roots-137223">nearly 95,000 square miles</a> (250,000 square kilometers) and hold over 20% of Earth’s surface fresh water. <a href="https://coast.noaa.gov/states/fast-facts/great-lakes.html">More than 30 million people</a> in the U.S. and Canada rely on them for drinking water. The lakes support a multibillion-dollar maritime economy, and the lands around them provided many of the raw materials – timber, coal, iron – that fueled the Midwest’s emergence as an industrial heartland.</p>
<p>Despite their enormous importance, the lakes were <a href="https://www.ijc.org/en/great-lakes-1972-water-quality-agreement">degraded for well over a century</a> as industry and development expanded around them. By the 1960s, rivers like the Cuyahoga, Buffalo and Chicago were so polluted that they were <a href="https://www.environmentalcouncil.org/when_our_rivers_caught_fire">catching fire</a>. In 1965, Maclean’s magazine called Lake Erie, the smallest and shallowest Great Lake, “<a href="https://archive.macleans.ca/article/1965/11/1/death-of-a-great-lake">an odorous, slime-covered graveyard</a>” that “may have already passed the point of no return.” Lake Ontario <a href="https://scholar.uwindsor.ca/cgi/viewcontent.cgi?article=1012&context=ijcarchive">wasn’t far behind</a>.</p>
<p>In 1972, the U.S. and Canada signed the <a href="https://www.ijc.org/sites/default/files/C23.pdf">Great Lakes Water Quality Agreement</a>, a landmark pact to clean up the Great Lakes. Now, 50 years later, they have made progress, but there are new challenges and much unfinished business. </p>
<p>I <a href="https://scholar.google.com/citations?user=G4RniBIAAAAJ&hl=en">study the environment</a> and have written four books on U.S.-Canadian management of their shared border waters. In my view, the Great Lakes Water Quality Agreement was a watershed moment for environmental protection and an international model for regulating transboundary pollution. But I believe the people of the U.S. and Canada failed the Great Lakes by becoming complacent too soon after the pact’s early success. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of the Great Lakes-St. Lawrence Basin" src="https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463989/original/file-20220518-15-6nn6jw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Great Lakes-St Lawrence River Basin spans nearly half of North America, from northern Minnesota to New England.</span>
<span class="attribution"><a class="source" href="https://www.ijc.org/en/watersheds/great-lakes">International Joint Commission</a></span>
</figcaption>
</figure>
<h2>Starting with phosphates</h2>
<p>A major step in Canada-U.S. joint management of the Great Lakes came in 1909 when they signed the <a href="https://www.ijc.org/en/boundary-waters-treaty-1909">Boundary Waters Treaty</a>. The Great Lakes Water Quality Agreement built on this foundation by creating a framework to allow the two countries to cooperatively restore and protect these border waters. </p>
<p>However, as an executive agreement, rather than a formal government-to-government treaty, the pact has no legal mechanisms for enforcement. Instead, it relies on the U.S. and Canada to fulfill their commitments. The <a href="https://www.ijc.org/en/who/role">International Joint Commission</a>, an agency created under the Boundary Waters Treaty, carries out the agreement and tracks progress toward its goals. </p>
<p>The agreement set common targets for controlling a variety of pollutants in Lake Erie, Lake Ontario and the upper St. Lawrence River, which were the most polluted section of the Great Lakes system. One key aim was to reduce nutrient pollution, especially phosphates from detergents and sewage. These chemicals fueled huge blooms of algae that then died and decomposed, depleting oxygen in the water. </p>
<p>Like national water pollution laws enacted at the time, these efforts focused on point sources – pollutants released from discreet, readily identifiable points, such as discharge pipes or wells.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of the Great Lakes and connecting water bodies in profile." src="https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=250&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=250&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=250&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=314&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=314&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463987/original/file-20220518-20-uyapnj.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=314&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This profile view of the Great Lakes shows that Lake Erie is much shallower than the other lakes. As a result, its waters warm faster and are more vulnerable to algal blooms.</span>
<span class="attribution"><a class="source" href="https://twitter.com/NOAA_GLERL/status/1270022370640658437/photo/1">NOAA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Early results were encouraging. Both governments invested in new sewage treatment facilities and convinced manufacturers to <a href="https://www.nytimes.com/1970/05/03/archives/detergents-listed-in-phosphate-order.html">reduce phosphate loads in detergents and soaps</a>. But as phosphorus levels in the lakes declined, scientists soon detected other problems.</p>
<h2>Toxic contaminants</h2>
<p>In 1973, scientists reported a perplexing find in fish from Lake Ontario: <a href="http://dx.doi.org/%2010.1126/science.185.4150.523">mirex, a highly toxic organochloride pesticide</a> used mainly to kill ants in the southeast U.S. An investigation revealed that the <a href="https://www.nytimes.com/1976/09/03/archives/new-jersey-pages-chemical-flowing-illegally-into-niagara-toxic.html">Hooker Chemical company</a> was discharging mirex from its plant in Niagara Falls, New York. The contamination was so severe that New York State <a href="https://aliciapatterson.org/stories/northern-fish-mystery">banned eating popular types of fish</a> such as coho salmon and lake trout from Lake Ontario from 1976 to 1978, shutting down commercial and sport fishing in the lake. </p>
<p>In response to this and other findings, the U.S. and Canada updated the Great Lakes Water Quality Agreement in 1978 to cover all five lakes and focus on chemicals and toxic substances. This version formally adopted an <a href="https://ijc.org/sites/default/files/2019-05/WQB_PracticalStepstoImplementanEcosystemApproachinGreatLakesManagement_December1995.pdf">ecosystem approach</a> to pollution control that considered interactions between water, air and land – perhaps the first international agreement to do so. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/gBRcOLcEwF0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A tour of the Great Lakes and the nature in and around them.</span></figcaption>
</figure>
<p>In 1987, the two countries identified <a href="https://www.ijc.org/en/what/glwq-aoc">the most toxic hot spots</a> around the lakes and adopted action plans to clean them up. However, as <a href="https://press.ucalgary.ca/books/9781552388952/">scholars</a> of North American environmental regulations <a href="https://press.uchicago.edu/ucp/books/book/chicago/M/bo3629140.html">acknowledge</a>, both nations too often allowed industries to police themselves. </p>
<p>Since the 1990s, <a href="https://www.dec.ny.gov/data/DecDocs/932121/Report.HW.932121.2009-03-26.ToxicsChemicalsInTributariesToLakeOntario.pdf">studies</a> have identified toxic pollutants including <a href="https://doi.org/10.1021/acs.estlett.8b00019">PCBs</a>, <a href="https://doi.org/10.1016/j.envint.2020.106065">DDT</a> and chlordane in and around the Great Lakes, as well as lead, copper, arsenic and others. Some of these chemicals <a href="https://doi.org/10.1021/es501509r">continued to show up</a> because they were persistent and took a long time to break down. Others were banned but leached from contaminated sites and sediments. Still others came from a range of point and nonpoint sources, including <a href="https://www.ijc.org/sites/default/files/D9.pdf">many industrial sites</a> concentrated on shorelines.</p>
<p>Many hazardous sites have been slowly cleaned up. However, toxic pollution in the Great Lakes <a href="https://www.regions.noaa.gov/great-lakes/index.php/great_lakes-restoration-initiative/toxics/">remains a colossal problem</a> that is largely unappreciated by the public, since these substances don’t always make the water look or smell foul. Numerous <a href="https://ehp.niehs.nih.gov/doi/10.1289/ehp104">fish advisories</a> are still in effect across the region because of chemical contamination. Industries constantly bring new chemicals to market, and <a href="https://www.pbs.org/newshour/science/it-could-take-centuries-for-epa-to-test-all-the-unregulated-chemicals-under-a-new-landmark-bill">regulations lag far behind</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1004722065247698944"}"></div></p>
<h2>Nonpoint sources</h2>
<p>Another major challenge is <a href="https://www.epa.gov/nps/basic-information-about-nonpoint-source-nps-pollution">nonpoint source pollution</a> – discharges that come from many diffuse sources, such as runoff from farm fields. </p>
<p><a href="https://doi.org/10.1086/684646">Nitrogen levels</a> in the lakes have risen significantly because of agriculture. Like phosphorus, nitrogen is a nutrient that causes large blooms of algae in fresh water; it is one of the main ingredients in fertilizer, and is also found in human and animal waste. <a href="https://greatlakes.org/campaigns/sewage-overflows/">Sewage overflows</a> from cities and <a href="https://elpc.org/blog/the-great-lakes-cafos-and-water-quality/">waste and manure runoff</a> from industrial agriculture carry heavy loads of nitrogen into the lakes.</p>
<p>As a result, algal blooms have <a href="https://www.glerl.noaa.gov/res/HABs_and_Hypoxia/bulletin.html">returned to Lake Erie</a>. In 2014, toxins in one of those blooms forced officials in Toledo, Ohio, to <a href="https://greatlakes.org/2019/08/five-years-later-lessons-from-the-toledo-water-crisis/">shut off the public water supply</a> for half a million people. </p>
<p>One way to address nonpoint source pollution is to set an overall limit for releases of the problem pollutant into local water bodies and then work to bring discharges down to that level. These measures, known as <a href="https://www.epa.gov/tmdl/overview-total-maximum-daily-loads-tmdls">Total Maximum Daily Loads</a>, have been applied or are in development for parts of the Great Lakes basin, including <a href="https://greatlakes.org/2020/02/statement-development-of-a-pollution-diet-for-western-lake-erie/">western Lake Erie</a>.</p>
<p>But this strategy relies on states, along with <a href="https://www.freshlawblog.com/2016/06/02/us-epas-great-lakes-restoration-initiative-grants-for-voluntary-action-a-striking-contrast-to-the-chesapeake-bay-tmdl/">voluntary steps by farmers</a>, to curb pollution releases. Some Midwesterners would prefer a regional approach like the strategy for Chesapeake Bay, where states asked the U.S. government to write a sweeping <a href="https://www.chesapeakebay.net/what/programs/total_maximum_daily_load">federal TMDL for key pollutants</a> for the bay’s entire watershed.</p>
<p>In 2019, Toledo voters adopted a <a href="https://theconversation.com/how-giving-legal-rights-to-nature-could-help-reduce-toxic-algae-blooms-in-lake-erie-115351">Lake Erie Bill of Rights</a> that would have permitted citizens to sue when Lake Erie was being polluted. Farmers <a href="https://www.michiganradio.org/environment-science/2020-02-28/lake-erie-bill-of-rights-declared-unconstitutional">challenged the measure in court</a>, and it was declared unconstitutional.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CdmlEGTMwkA/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Warming and flooding</h2>
<p><a href="https://nca2018.globalchange.gov/chapter/21/">Climate change</a> is now complicating Great Lakes cleanup efforts. Warmer water can affect oxygen concentrations, nutrient cycling and food webs in the lakes, potentially <a href="https://theconversation.com/warmer-wetter-wilder-38-million-people-in-the-great-lakes-region-are-threatened-by-climate-change-170195">intensifying problems</a> and converting nuisances into major challenges. </p>
<p>Flooding driven by climate change threatens to <a href="https://theconversation.com/climate-change-threatens-drinking-water-quality-across-the-great-lakes-131883">contaminate public water supplies</a> around the lakes. Record-high water levels are <a href="https://theconversation.com/great-lakes-flooding-the-warning-signs-that-homes-must-be-moved-122697">eroding shorelines and wrecking infrastructure</a>. And new problems are emerging, including <a href="https://www.greatlakesnow.org/2021/05/chemical-impact-microplastic-pollution/">microplastic pollution</a> and “forever chemicals” such as <a href="https://news.wisc.edu/study-finds-tributaries-play-significant-role-in-great-lakes-pfas-loading/">PFAS and PFOA</a>. </p>
<p>It will be challenging for the U.S. and Canada to make progress on this complex set of problems. Key steps include prioritizing and funding cleanup of toxic zones, finding ways to halt agricultural runoff and building new sewer and stormwater infrastructure. If the two countries can muster the will to aggressively tackle pollution problems, as they did with phosphates in the 1970s, the Great Lakes Water Quality Agreement gives them a framework for action.</p><img src="https://counter.theconversation.com/content/181037/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Macfarlane has received funding from the Social Sciences and Humanities Research Council and Western Michigan University. </span></em></p>Cleaning up the Great Lakes was a big job when the US and Canada undertook it in 1972. Today it’s far more challenging.Daniel Macfarlane, Associate Professor of Environment and Sustainability, Western Michigan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1660382021-11-10T11:35:23Z2021-11-10T11:35:23ZPromising COVID treatments could be growing under the sea – here’s how to find them<figure><img src="https://images.theconversation.com/files/431038/original/file-20211109-23-bwnn83.jpg?ixlib=rb-1.1.0&rect=319%2C253%2C6765%2C4506&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/forest-seaweed-723657958">divedog/Shutterstock</a></span></figcaption></figure><p>More than 18 months into the pandemic, we’re still hunting for effective antiviral treatments for COVID – medicines that target the coronavirus itself and stop it from developing in the body. </p>
<p>So far we have only a handful of options. Remdesivir has been authorised for use, but the latest research shows it doesn’t improve outcomes for COVID patients, and so the World Health Organization has <a href="https://www.who.int/news-room/feature-stories/detail/who-recommends-against-the-use-of-remdesivir-in-covid-19-patients">recommended</a> it not be used. A new alternative, molnupiravir, will <a href="https://www.reuters.com/business/healthcare-pharmaceuticals/uk-roll-out-covid-19-antiviral-drug-trial-this-month-health-security-agency-2021-11-07/">soon be available</a>, but demand will be high. It could also be <a href="https://www.liverpoolecho.co.uk/news/uk-world-news/molnupiravir-covid-19-pill-side-22079473">very expensive</a> for some patients. </p>
<p>So if we need alternative antivirals, where will we find them? Possibly in nature. It’s an outstanding hub for valuable natural compounds, and provided us with one of the most important scientific discoveries in history: <a href="https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html">penicillin</a>, the first naturally occurring antibiotic to be used therapeutically. Thanks to this drug, various diseases caused by bacteria are no longer life threatening.</p>
<p>There’s a very good chance that researchers could discover a highly effective antiviral agent in nature too, if they were able to test all of the substances within the natural environment. This, however, would be an enormous task. So we need to find shortcuts – which is something I and my colleagues have been <a href="https://www.mdpi.com/1660-3397/19/8/406">working on</a>.</p>
<h2>Finding medicines under the waves</h2>
<p>The marine environment in particular is a treasure trove for potential new medicines. Many products derived from marine organisms have been <a href="https://www.sciencedirect.com/science/article/pii/S2590262820300125#s0155">approved</a> by the US Food and Drug Administration for medical use, for example, and many others are <a href="https://www.marinepharmacology.org">currently in different stages</a> of clinical trials. However, the sea and its natural products are still under-investigated as far as medicines are concerned.</p>
<p>One set of substances that are particularly interesting are marine sulphated polysaccharides, or MSPs. These are a type of carbohydrate that contain sulphur, and are mainly found in the cell walls of marine algae or seaweeds. They’re also less commonly found in some fish skins and in mangrove plants. </p>
<p>They’re significant because they’ve shown that they can inhibit <a href="https://www.mdpi.com/1660-3397/19/8/406">many disease-causing viruses</a>, such as herpes simplex virus, HIV, chikungunya virus, cytomegalovirus, influenza and hepatitis virus. </p>
<p>But even if we know MSPs in general are worth investigating, discovering which ones specifically are effective against SARS-CoV-2, the virus that causes COVID, would be very time and resource-consuming using traditional laboratory testing.</p>
<h2>Simulating interactions</h2>
<p>To get around this, my colleagues and I used <a href="https://www.mdpi.com/1660-3397/19/8/406">computer-assisted methods</a> to predict how MSPs would behave with the coronavirus, and so filter out those unlikely to work against it. Many drugs currently on the market were developed with this kind of assistance, including the flu treatment zanamivir and the HIV drugs nelfinavir and saquinavir.</p>
<p>First, we looked at past research, focusing on papers that mentioned MSPs having an effect against different viruses. We looked at around 80 papers, spanning 25 years, and came up with a shortlist of 45 substances that might potentially have an antiviral effect and so be worth investigating further. </p>
<p>These shortlisted MSPs came from various marine sources, including different types of algae, microalgae, sea cucumbers and squid cartilage. </p>
<figure class="align-center ">
<img alt="An illustration of SARS-CoV-2, with its spike proteins shown in orange" src="https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431039/original/file-20211109-17-174ubl6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We wanted to see which substances would bind best to the virus’s spike proteins, shown here in orange.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/sarscov2-coronavirus-virus-which-causes-covid19-1697804203">Kateryna Kon/Shutterstock</a></span>
</figcaption>
</figure>
<p>We then built 3D computer-generated versions of these molecules, together with the spike protein that covers the outside of the coronavirus, which is what the virus uses to get inside cells. Using these computer models, we then simulated how well each MSP would bind to the spike protein. This process – of using computer simulations to test binding – is known as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3151162/">“molecular docking”</a>. </p>
<p>Knowing that we should focus interactions with the spike protein wasn’t just a guess. A substance chemically similar to the MSPs we were looking at, called heparin, had recently <a href="https://www.sciencedirect.com/science/article/pii/S0092867420312307">shown promise</a> against SARS-CoV-2 by binding to its spike proteins and stopping it from infecting cells. (The issue with heparin is that it’s a blood thinner, and so it’s not highly suitable as a COVID medicine.)</p>
<p>If we could find MSPs that bound to the virus in the same way as heparin, then we’d have a list of substances that could plausibly have the same antiviral effect as it too. And so, we ran computer simulations for all of our MSPs.</p>
<h2>New substances of interest emerge</h2>
<p>Of the 45 MSPs we shortlisted, nine showed the same binding activity as heparin, suggesting they would have real promise as avenues for future drug development. And while some of these had already been flagged as having potential use against SARS-CoV-2 – such as carrageenan, an algae product already used in nasal sprays and lozenges for the common cold – crucially, five hadn’t.</p>
<figure class="align-center ">
<img alt="The brown sea algae Hormophysa cuneiformis" src="https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431048/original/file-20211109-17-1geyf17.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One of the five unflagged substances – sulfated galactofucan – can be found in brown seaweeds like this one.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hormophysa-cuneiformis-brown-algae-large-group-1890174499">my life is ams/Shutterstock</a></span>
</figcaption>
</figure>
<p>Carrageenan is <a href="https://clinicaltrials.gov/ct2/show/NCT04590365">already being tested</a> for its potential to stop people from being infected with COVID. The other substances we uncovered are some way behind, but hopefully with their potential having been speedily revealed, they can now move on to the next stage of drug development – lab testing to properly confirm their activity against SARS-CoV-2. If that were to go well, then a marine-derived drug for treating COVID could be something we see in the future.</p><img src="https://counter.theconversation.com/content/166038/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Abdalla Mohamedsalih does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Substances found in algae, squid and fish all have potential antiviral properties.Abdalla Mohamedsalih, PhD Candidate in the School of Computing, Engineering and Physical Sciences, University of the West of ScotlandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1645292021-09-17T12:19:15Z2021-09-17T12:19:15ZScientists at work: We use environmental DNA to monitor how human activities affect life in rivers and streams<figure><img src="https://images.theconversation.com/files/420917/original/file-20210913-21-185he0a.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3259%2C1832&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Environmental DNA is a promising tool for tracking species in freshwater ecosystems like Oregon's Elkhorn Creek.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/NZgE7n">Greg Shine, BLM/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Rivers, lakes and wetlands cover just 1% of the Earth’s surface but are home to nearly 10% of all species, including fish, mammals, birds, insects and crustaceans. But these rich, <a href="https://wwfcee.org/pdf_collections/7/world_s_forgotten_fishes__final_april9_.pdf">diverse</a> ecosystems are <a href="https://wwf.panda.org/discover/our_focus/freshwater_practice/the_world_s_forgotten_fishes/">in free fall</a>. Worldwide, species are <a href="https://www.un.org/sustainabledevelopment/blog/2019/05/nature-decline-unprecedented-report/">declining faster now</a> than at any other time in human history, and fresh waters are losing more species than land or ocean ecosystems.</p>
<p>Today about <a href="https://www.iucn.org/theme/species/our-work/freshwater-biodiversity">1 in 4 freshwater creatures face extinction</a>. Wetlands are disappearing <a href="https://doi.org/10.1093/biosci/biaa002">three times faster than forests</a>. Across the globe, water quality is plummeting, polluted by <a href="https://uneplive.unep.org/media/docs/assessments/unep_wwqa_report_web.pdf">plastic, sewage, mining sludge, industrial and agricultural chemicals and much more</a>. </p>
<p>It’s challenging to study how these stresses are affecting aquatic life. There are many diverse threats, and river networks cover broad geographic regions. Often they run through remote, nearly inaccessible areas. Current techniques for monitoring freshwater species are <a href="https://doi.org/10.1111/j.1365-2664.2010.01864.x">labor-intensive and costly</a>.</p>
<p>In our <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1002/eap.2389">work</a> as <a href="https://scholar.google.fr/citations?user=rhmblP8AAAAJ&hl=fr">researchers</a> in <a href="https://scholar.google.com/citations?user=hxHYAA8AAAAJ&hl=en">ecology</a>, we are testing a new method that can vastly expand biomonitoring: using environmental DNA, or eDNA, in rivers to <a href="https://doi.org/10.1016/j.tree.2014.04.003">catalog and count species</a>. Federal and local agencies need this data to restore water quality and save dwindling species from extinction. </p>
<figure>
<iframe src="https://player.vimeo.com/video/66103145" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">This preview of the film “Hidden Rivers” reveals the diverse and little-known life in Southern Appalachian waterways.</span></figcaption>
</figure>
<h2>Traditional methods are slow and expensive</h2>
<p>With traditional biomonitoring methods, scientists count individual species and their abundance at just <a href="https://doi.org/10.1111/j.1365-2664.2010.01864.x">a few sites</a>. For example, one recent study of <a href="https://doi.org/10.1086/676997">mountaintop mining impacts on fish in West Virginia</a> sampled just four sites with a team of four researchers. </p>
<p>Collecting and identifying aquatic organisms requires highly skilled ecologists and taxonomists with expertise in a wide variety of freshwater species. For each sample of fish or invertebrates collected in the field, it takes from hours to weeks to identify all of the species. Only wealthy nations can afford this costly process.</p>
<p>Conserving threatened and endangered species and keeping river ecosystems healthy requires monitoring broad areas over time. Sensitive aquatic insects and fish species are the freshwater equivalent of the proverbial canary in a coal mine: If these species are absent, that’s a strong indicator of water quality problems. The cause may be mining, agriculture, urbanization or other sources, as well as <a href="https://www.nwf.org/Magazines/National-Wildlife/2012/AugSept/Animals/Appalachian-Rivers">dams</a> that block animals’ downstream movements.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/W3lcHdFyzrQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientists sample for fish in a Maryland stream by ‘electrofishing’ – stunning fish with a mild electrical pulse so they can be collected, identified and released after the shock wears off.</span></figcaption>
</figure>
<h2>Free-floating genetic evidence</h2>
<p>Innovations in genetic technology have created a powerful, affordable new tool that we are now testing. The process involves extracting eDNA from genetic material floating in the water – skin, scales, feces and single-celled organisms, such as bacteria. </p>
<p>By analyzing this genetic information, we can <a href="https://doi.org/10.1111/j.1365-294X.2012.05470.x">detect a wide range of species</a>. We started considering using eDNA for our research in 2018, after several studies demonstrated its power to monitor single species of interest or groups of organisms in <a href="https://doi.org/10.1016/j.tree.2014.04.003">rivers</a> and <a href="https://theconversation.com/fishing-for-dna-free-floating-edna-identifies-presence-and-abundance-of-ocean-life-75957">oceans</a>.</p>
<p>Collecting eDNA is easy: One 4-ounce water sample can capture remnant DNA from thousands of aquatic species. Another benefit is that it doesn’t require killing wildlife for identification.</p>
<p>In the lab, we analyze the DNA from different taxonomic groups one by one: bacteria, algae, fish and <a href="https://www.epa.gov/national-aquatic-resource-surveys/indicators-benthic-macroinvertebrates">macroinvertebrates</a> – organisms that lack backbones and are large enough to see, such as snails, worms and beetles. Many researchers study just one group, but we assess all of them at the same time. </p>
<p>We then match our DNA sequences with freshwater species that are already catalogued in existing databases. In this way, we can chart the distribution and abundance of these organisms within and across rivers.</p>
<p>This process requires just a cheap filter, a syringe and vials, and anyone can do it. Commercial eDNA companies charge less than $200 to extract and sequence a sample. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic showing how scientists analyze eDNA to detect different species." src="https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421209/original/file-20210914-13-u7g2zq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most eDNA the authors collect from streams is microbial (the gray DNA in the cartoon above). Without special techniques, they would not ‘see’ the less frequent DNA from other taxonomic groups, so their surveys would generate a species abundance curve like the one on the bottom left, in which most groups of conservation concern are too rare to detect or fall into the ‘long tail’ of rare occurrences. By using targeted primers – short stretches of DNA that are unique to specific groups of organisms – they can amplify the eDNA of less abundant groups, like algae, arthropods and fish, as shown on the right.</span>
<span class="attribution"><span class="source">Emily Bernhardt, produced using Biorender</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Altered rivers</h2>
<p>Using this method, we extensively surveyed 93 rivers in West Virginia – looking at the entire tree of life, from the tiniest bacteria to fish – in two days with a four-person team. </p>
<p>The Appalachian rivers that we study teem with life. These are some of the world’s most biologically diverse temperate freshwater ecosystems, home to <a href="https://www.conservationfisheries.org/appalachia">many fish species</a>, as well as salamanders, crayfish, mussels and aquatic insects. <a href="https://www.natureserve.org/publications/rivers-life-critical-watersheds-protecting-freshwater-biodiversity">Many are found nowhere else</a>. We tallied <a href="https://doi.org/10.1002/eap.2389">more than 10,000 different species</a> in those 93 waterways. </p>
<p>The area where we worked is an intensive coal mining region, which heavily affects waterways. Liquids draining from mines are <a href="https://www.epa.gov/nps/abandoned-mine-drainage">acidic</a>, but in this region they react with limestone rock, so the net effect is to make local streams alkaline. Mine drainage also increases streams’ salinity and concentrations of <a href="https://doi.org/10.1021/es301144q">sulfate and other contaminants</a>. Our research revealed that mined watersheds held 40% fewer species than areas without mining operations, and the organisms we detected were less abundant than in unaffected rivers. </p>
<h2>Assessing river health</h2>
<p>We believe this new approach represents a revolution for biomonitoring, expanding our ability to quantify and study freshwater life. It’s also an important new conservation tool, allowing scientists to track changes in populations of endangered or invasive species. Researchers also can use eDNA to monitor biodiversity or discover new species in oceans or soils. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1303976383178309633"}"></div></p>
<p>This <a href="https://doi.org/10.1002/fee.1490">open-science method</a> makes all DNA data widely available, with nearly all sequences placed in public repositories. Moving forward, we expect that it will aid many types of research, as well as state and local monitoring and conservation programs. Investments in collecting eDNA and identifying organisms and analyzing their genetic signatures will continue to make it a more effective tool.</p>
<p>[<em>Over 100,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p>
<p>Efforts are underway to better target various individual species, focusing on those that are endangered, invasives that damage ecosystems and sensitive species that serve as indicators of river health. Scientists are freezing eDNA samples at -112 degrees F (-80 C) in expectation that technological advances may yield <a href="https://doi.org/10.1038/s41559-018-0614-3">more information in the future</a>.</p>
<p>Traditional monitoring approaches remain valuable, but eDNA adds an important new tool to the toolkit. Together, these approaches can begin to answer many questions about food webs, the conservation status of species, reproduction rates, species interactions, organisms’ health, disease and more.</p><img src="https://counter.theconversation.com/content/164529/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marie Simonin is a research scientist at INRAE, the French National Research Institute for Agriculture, Food and Environment.</span></em></p><p class="fine-print"><em><span>Emily S. Bernhardt has received funding to research the impacts of mountaintop removal coal mining from the Foundation for the Carolinas and the National Science Foundation, which supported the work described in this article. She currently is engaged as an expert on these impacts by the US Department of Justice.</span></em></p>Rivers are among the most embattled ecosystems on Earth. Researchers are testing a new, inexpensive way to study river health by using eDNA to count the species that rivers harbor.Marie Simonin, Research Scientist, InraeEmily S. Bernhardt, Professor of Biology, Duke UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1665422021-08-26T12:11:04Z2021-08-26T12:11:04ZScientists are using new satellite tech to find glow-in-the-dark milky seas of maritime lore<figure><img src="https://images.theconversation.com/files/418509/original/file-20210830-23-4gkx18.png?ixlib=rb-1.1.0&rect=0%2C248%2C1163%2C838&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For centuries, sailors have told tales of milky seas – huge swaths of ocean glowing on dark nights, seen in blue in this false–color satellite image. </span> <span class="attribution"><span class="source">Steven D. Miller/NOAA</span></span></figcaption></figure><blockquote>
<p>“The whole appearance of the ocean was <a href="https://www.science-frontiers.com/sf086/sf086g12.htm">like a plain covered with snow</a>. There was scarce a cloud in the heavens, yet the sky … appeared as black as if a storm was raging. The scene was one of awful grandeur, the sea having turned to phosphorus, and the heavens being hung in blackness, and the stars going out, seemed to indicate that all nature was preparing for that last grand conflagration which we are taught to believe is to annihilate this material world.”<br>
– Captain Kingman of the American clipper ship Shooting Star, offshore of Java, Indonesia, 1854</p>
</blockquote>
<p>For centuries, sailors have been reporting strange encounters like the one above. These events are called milky seas. They are a rare nocturnal phenomenon in which the ocean’s surface emits a steady bright glow. They can cover thousands of square miles and, thanks to the colorful accounts of 19th-century mariners like Capt. Kingman, milky seas are a well-known part of maritime folklore. But because of their remote and elusive nature, they are extremely difficult to study and so remain more a part of that folklore than of science.</p>
<p>I’m a <a href="https://www.cira.colostate.edu/staff/miller-steve/">professor of atmospheric science</a> specializing in <a href="https://www.cira.colostate.edu">satellites used to study Earth</a>. Via a stat-of-the-art generation of satellites, my colleagues and I have developed a new way <a href="https://doi.org/10.1038/s41598-021-94823-z">to detect milky seas</a>. Using this technique, we aim to learn about these luminous waters remotely and guide research vessels to them so that we can begin to reconcile the surreal tales with scientific understanding.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A glass beaker glowing with a bluish light." src="https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=666&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=666&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=666&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=837&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=837&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417912/original/file-20210825-17175-1prypkq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=837&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The bioluminescence in milky seas is caused by a type of bacteria.</span>
<span class="attribution"><span class="source">Steve. H. D. Haddock/MBARI</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Sailors’ tales</h2>
<p>To date, only one research vessel <a href="https://doi.org/10.1016/0022-0981(88)90152-9">has ever encountered a milky sea</a>.
That crew collected samples and found a strain of luminous bacteria called <em>Vibrio harveyi</em> colonizing algae at the water’s surface. </p>
<p>Unlike bioluminescence that happens close to shore, where small organisms called dinoflagellates flash brilliantly when disturbed, luminous bacteria work in an entirely different way. Once their population gets large enough – about 100 million individual cells per milliliter of water – a sort of <a href="https://doi.org/10.1128/AEM.72.4.2295-2297.2006">internal biological switch is flipped</a> and they all start glowing steadily. </p>
<p>Luminous bacteria cause the particles they colonize to glow. Researchers think the purpose of this glow could be <a href="https://doi.org/10.1146/annurev-marine-120308-081028">to attract fish that eat them</a>. These bacteria thrive in the guts of fishes, so when their populations get too big for their main food supply, a fish’s stomach makes a great second option. In fact, if you go into a refrigerated fish locker and turn off the light, you may notice that some fish emit a <a href="http://www.floridasportsman.com/2017/12/12/glow-dark-seafood/">greenish-blue glow</a> – this is <a href="https://seafood.oregonstate.edu/sites/agscid7/files/snic/glowing-seafood.pdf">bacterial light</a>. </p>
<p>Now imagine if a gargantuan number of bacteria, spread across a huge area of open ocean, all started glowing simultaneously. That makes a milky sea.</p>
<p>While biologists know a lot about these bacteria, what causes these massive displays remains a mystery. If bacteria growing on algae were the main cause of milky seas, they’d be happening all over the place, all the time. Yet, per surface reports, only about <a href="https://doi.org/10.1073/pnas.0507253102">two or three milky seas occur per year</a> worldwide, <a href="https://doi.org/10.1038/s41598-021-94823-z">mostly in the waters of the northwest Indian Ocean and off the coast of Indonesia</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image showing four different panels, with a swoosh shape apparent in all of them." src="https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=603&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=603&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=603&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=758&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=758&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417840/original/file-20210825-25-12ysz9o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=758&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers found a milky sea event off the coast of Somalia, seen here as a pale swoosh in the top left image. The other panels show sea surface temperature, ocean currents and chlorophyll.</span>
<span class="attribution"><span class="source">Steven D. Miller/NOAA</span></span>
</figcaption>
</figure>
<h2>Satellite solutions</h2>
<p>If scientists want to learn more about milky seas, they need to get to one while it’s happening. Trouble is, milky seas are so elusive that it has been almost impossible to sample them. This is where my research comes into play.</p>
<p>Satellites offer a practical way to monitor the vast oceans, but it takes a special instrument able to detect light around 100 million times fainter than daylight. My colleagues and I first explored the potential of satellites in 2004 when we used U.S. defense satellite imagery <a href="https://doi.org/10.1073/pnas.0507253102">to confirm a milky sea</a> that a British merchant vessel, the SS Lima, reported in 1995. But the images from these satellites were very noisy, and there was no way we could use them as a search tool.</p>
<p>We had to wait for a better instrument – the Day/Night Band – planned for the National Oceanic and Atmospheric Administration’s new constellation of satellites. The new sensor went live in late 2011, but our hopes were initially dashed when we realized the Day/Night Band’s <a href="https://doi.org/10.1073/pnas.1207034109">high sensitivity</a> also detected <a href="https://doi.org/10.1088/0034-4885/34/3/302">light emitted by air molecules</a>. It took years of studying Day/Night Band imagery to be able to interpret what we were seeing.</p>
<p>Finally, on a clear moonless night in early 2018, an odd swoosh-shaped feature appeared in the Day/Night Band imagery offshore Somalia. We compared it with images from the nights before and after. While the clouds and airglow features changed, the swoosh remained. We had found a milky sea! And now we knew how to look for them.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A satellite image of a massive, question mark-shaped white area off the coast of a brightly lit island." src="https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=601&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=601&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=601&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417845/original/file-20210825-15-oadtk1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This milky sea off the coast of Java was the size of Kentucky and lasted for more than a month.</span>
<span class="attribution"><span class="source">Steven D. Miller/NOAA</span></span>
</figcaption>
</figure>
<p>The “aha!” moment that unveiled the full potential of the Day/Night Band came in 2019. I was browsing the imagery looking for clouds masquerading as milky seas when I stumbled upon an astounding event south of the island of Java. I was looking at an enormous swirl of glowing ocean that spanned over 40,000 square miles (100,000 square km) – roughly the size of Kentucky. The imagery from the new sensors provided a level of detail and clarity that I hadn’t imagined possible. I watched in amazement as the glow slowly drifted and morphed with the ocean currents. </p>
<p>We learned a lot from this watershed case: how milky seas are related to sea surface temperature, biomass and the currents – important clues to understanding their formation. As for the estimated number of bacteria involved? Approximately 100 billion trillion cells – nearly the total estimated number of stars <a href="https://www.space.com/26078-how-many-stars-are-there.html">in the observable universe</a>!</p>
<figure class="align-center ">
<img alt="Two satellite images of Java showing a large question mark-shaped area of light-colored sea surface." src="https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&rect=0%2C0%2C1010%2C1022&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=763&fit=crop&dpr=1 754w, https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=763&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/417711/original/file-20210824-17640-s8f2g3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=763&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The two images on the left were taken with older satellite technology while the images on the right show the high-definition imagery produced by the Day/Night Band sensor.</span>
<span class="attribution"><span class="source">Steven D. Miller/NOAA</span></span>
</figcaption>
</figure>
<h2>The future is bright</h2>
<p>Compared with the old technology, viewing Day/Night Band imagery is like putting on glasses for the first time. My colleagues and I have analyzed thousands of images taken since 2013, and we’ve uncovered 12 milky seas so far. Most happened in the very same waters where mariners have been reporting them for centuries. </p>
<p>Perhaps the most practical revelation is how long a milky sea can last. While some last only a few days, the one near Java carried on for over a month. That means that there is a chance to deploy research craft to these remote events while they are happening. That would allow scientists to measure them in ways that reveal their full composition, how they form, why they’re so rare and what their ecological significance is in nature.</p>
<p>If, like Capt. Kingman, I ever do find myself standing on a ship’s deck, casting a shadow toward the heavens, I’m diving in! </p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklysmart">You can get our highlights each weekend</a>.]</p><img src="https://counter.theconversation.com/content/166542/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steven D. Miller receives funding from the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, and the Office of Naval Research.</span></em></p>When conditions are just right in some parts of the Indian Ocean, a type of bacteria will multiply and start to glow. Satellites are helping scientists study these milky seas for the first time.Steven D. Miller, Professor of Atmospheric Science, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1644592021-08-05T12:48:25Z2021-08-05T12:48:25ZFrom CRISPR to glowing proteins to optogenetics – scientists’ most powerful technologies have been borrowed from nature<figure><img src="https://images.theconversation.com/files/414624/original/file-20210804-15-1fuewod.jpg?ixlib=rb-1.1.0&rect=391%2C30%2C3002%2C1822&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Crystal jellyfish contain glowing proteins that scientists repurpose for an endless array of studies.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/crystal-jellyfish-royalty-free-image/1013185852?adppopup=true">Weili Li/Moment via Getty Images</a></span></figcaption></figure><p><a href="https://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397/">Watson and Crick</a>, <a href="https://www.nobelprize.org/prizes/physics/1933/schrodinger/biographical/">Schrödinger</a> and <a href="https://www.nobelprize.org/prizes/physics/1921/einstein/biographical/">Einstein</a> all made theoretical breakthroughs that have changed the world’s understanding of science. </p>
<p>Today big, game-changing ideas are less common. New and improved techniques are the <a href="https://doi.org/10.1038/nmeth1004-1">driving force behind modern scientific research and discoveries</a>. They allow scientists – <a href="https://scholar.google.com/citations?user=RpiSPiwAAAAJ&hl=en&oi=ao">including chemists like me</a> – to do our experiments faster than before, and they shine light on areas of science hidden to our predecessors. </p>
<p>Three cutting-edge techniques – the gene-editing tool <a href="https://www.newscientist.com/definition/what-is-crispr/">CRISPR</a>, <a href="https://doi.org/10.1242/jcs.072744">fluorescent proteins</a> and <a href="https://www.scientificamerican.com/article/optogenetics-controlling/">optogenetics</a> – were all inspired by nature. Biomolecular tools that have worked for bacteria, jellyfish and algae for millions of years are now being used in medicine and biological research. Directly or indirectly, they will change the lives of everyday people.</p>
<h2>Bacterial defense systems as genetic editors</h2>
<p>Bacteria and viruses battle themselves and one another. They are at constant biochemical war, <a href="https://doi.org/10.1016/j.cub.2019.04.024">competing for scarce resources</a>. </p>
<p>One of the weapons that bacteria have in their arsenal is the <a href="https://www.livescience.com/58790-crispr-explained.html">CRISPR-Cas system</a>. It is a genetic library consisting of short repeats of DNA gathered over time from hostile viruses, paired with a protein called Cas that can cut viral DNA as if with scissors. In the natural world, when bacteria are attacked by viruses whose DNA has been stored in the CRISPR archive, the CRISPR-Cas system hunts down, cuts and destroys the viral DNA.</p>
<p>Scientists have repurposed these weapons for their own use, with groundbreaking effect. Jennifer Doudna, a biochemist based at the University of California, Berkeley, and French microbiologist Emmanuelle Charpentier shared the <a href="https://theconversation.com/nobel-prize-for-chemistry-honors-exquisitely-precise-gene-editing-technique-crispr-a-gene-engineer-explains-how-it-works-147701">2020 Nobel Prize in chemistry</a> for <a href="https://www.nobelprize.org/prizes/chemistry/2020/doudna/lecture/">the development of</a> <a href="https://theconversation.com/nobel-prize-for-crispr-honors-two-great-scientists-and-leaves-out-many-others-147730">CRISPR-Cas as a gene-editing technique</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="French researcher Emmanuelle Charpentier (left) and U.S. biochemist Jennifer Doudna (right)" src="https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414580/original/file-20210804-21-1k8hfpd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">French microbiologist Emmanuelle Charpentier (left) and U.S. biochemist Jennifer Doudna shared the 2020 Nobel Prize in Chemistry for development of the CRISPR-Cas gene editing technique.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/french-researcher-in-microbiology-genetics-and-biochemistry-news-photo/493945408?adppopup=true">Miguel Riopa/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.genome.gov/human-genome-project">Human Genome Project</a> has provided a nearly complete genetic sequence for humans and given scientists a template to sequence all other organisms. However, before CRISPR-Cas, we researchers didn’t have the tools to easily access and edit the genes in living organisms. Today, thanks to CRISPR-Cas, lab work that used to take months and years and cost hundreds of thousands of dollars can be done in less than a week for just a few hundred dollars. </p>
<p>There are more than 10,000 genetic disorders caused by mutations that occur on only one gene, the <a href="http://hihg.med.miami.edu/thromboticstorm/genetics-overview/single-gene-disorders">so-called single-gene disorders</a>. They affect millions of people. <a href="https://www.genome.gov/Genetic-Disorders/Sickle-Cell-Disease">Sickle cell anemia</a>, <a href="https://www.cff.org/What-is-CF/Genetics/CF-Genetics-The-Basics/">cystic fibrosis</a> and <a href="https://doi.org/10.31887/DCNS.2016.18.1/pnopoulos">Huntington’s disease</a> are among the most well-known of these disorders. These are all obvious targets for CRISPR therapy because it is much simpler to fix or replace just one defective gene rather than needing to correct errors on multiple genes. </p>
<p>For example, in preclinical studies, <a href="https://doi.org/10.1056/NEJMoa2107454">researchers injected</a> an encapsuled CRISPR system into patients born with a rare genetic disease, <a href="https://rarediseases.info.nih.gov/diseases/656/familial-transthyretin-amyloidosis">transthyretin amyloidosis</a>, that causes fatal nerve and heart conditions. Preliminary results from the study demonstrated <a href="https://www.nature.com/articles/d41586-021-01776-4">that CRISPR-Cas can be injected</a> directly into patients in such a way that it can find and edit the faulty genes associated with a disease. In the six patients included in this landmark work, the encapsuled CRISPR-Cas minimissiles reached their target genes and did their job, causing a significant drop in a <a href="https://www.nature.com/scitable/topicpage/protein-misfolding-and-degenerative-diseases-14434929/">misfolded protein</a> associated with the disease. </p>
<h2>Jellyfish light up the microscopic world</h2>
<p>The <a href="https://faculty.washington.edu/cemills/Aequorea.html">crystal jellyfish, <em>Aequorea victoria</em></a>, which drifts aimlessly in the northern Pacific, has no brain, no anus and no poisonous stingers. It is an unlikely candidate to ignite a revolution in biotechnology. Yet on the periphery of its umbrella, it has about 300 photo-organs that give off pinpricks of green light that have changed the way science is conducted.</p>
<p>This bioluminescent light in the jellyfish stems from a luminescent protein called aequorin and a fluorescent molecule called <a href="https://doi.org/10.1242/jcs.072744">green fluorescent protein</a>, or GFP. In modern biotechnology GFP acts as a molecular lightbulb that can be fused to other proteins, allowing researchers to track them and to see when and where proteins are being made in the cells of living organisms. Fluorescent protein technology is used in thousands of labs every day and has resulted in the awarding of two Nobel Prizes, <a href="https://www.nobelprize.org/prizes/chemistry/2008/popular-information/">one in 2008</a> and the <a href="https://www.nobelprize.org/prizes/chemistry/2014/summary/">other in 2014</a>. And fluorescent proteins have now been found in <a href="https://doi.org/10.1242/jcs.072744">many more species</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Fluorescent bacteria in petri dish and test tube" src="https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414422/original/file-20210803-13-vphczn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fluorescent proteins, shown here glowing inside <em>E. coli</em> bacteria, allow researchers to visualize biological structures and processes.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/red-and-green-fluorescent-proteins-in-escherichia-royalty-free-image/124368916?adppopup=true">Fernan Federici/Moment via Getty Images</a></span>
</figcaption>
</figure>
<p>This technology proved its utility once again when researchers created genetically modified <a href="https://doi.org/10.1016/j.cell.2020.05.042">COVID-19 viruses that express GFP</a>. The resulting fluorescence makes it possible to follow the path of the viruses as they enter the respiratory system and bind to surface cells with hairlike structures. </p>
<h2>Algae let us play the brain neuron by neuron</h2>
<p>When algae, which depend on sunlight for growth, are placed in a large aquarium in a darkened room, they swim around aimlessly. But if a lamp is turned on, the algae will swim toward the light. The single-celled <a href="https://www.britannica.com/science/flagellate">flagellates</a> – so named for the whiplike appendages they use to move around – don’t have eyes. Instead, they have a structure called an eyespot that distinguishes between light and darkness. The eyespot is studded with <a href="https://doi.org/10.1073/pnas.1525538113">light-sensitive proteins called channelrhodopsins</a>. </p>
<p>In the early 2000s, <a href="https://doi.org/10.1038/nn1525">researchers discovered</a> that when they genetically inserted these channelrhodopsins into the nerve cells of any organism, illuminating the channelrhodopsins with blue light caused neurons to fire. This technique, known as optogenetics, involves inserting the algae gene that makes channelrhodopsin into neurons. When a pinpoint beam of blue light is shined on these neurons, the channelrhodopsins open up, calcium ions flood through the neurons and the neurons fire. </p>
<p>Using this tool, scientists can stimulate groups of neurons selectively and repeatedly, thereby gaining a more precise understanding of which neurons to target to treat specific disorders and diseases. Optogenetics might hold the key to treating debilitating and deadly brain diseases, such as Alzheimer’s and Parkinson’s. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of amyloid plaque buildup on cells" src="https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414426/original/file-20210803-25-1p9rv2y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Optogenetics could help treat Alzheimer’s disease, which is characterized by the buildup of misfolded proteins called amyloid plaques.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/illustration-of-alzheimers-disease-royalty-free-illustration/1124681623?adppopup=true">Sciepro/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p>But optogenetics isn’t only useful for understanding the brain. Researchers have used optogenetic techniques <a href="https://doi.org/10.1038/s41591-021-01351-4">to partially reverse blindness</a> and have found promising results in clinical trials using optogenetics on patients with <a href="https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinitis-pigmentosa">retinitis pigmentosa</a>, a group of genetic disorders that break down retinal cells. And in mouse studies, the technique has been used to <a href="https://doi.org/10.1016/j.pbiomolbio.2019.08.013">manipulate heartbeat</a> and <a href="https://doi.org/10.1016/j.autneu.2020.102733">regulate bowel movements of constipated mice</a>. </p>
<h2>What else lies within nature’s toolbox?</h2>
<p>What undiscovered techniques does nature still hold for us? </p>
<p>According to <a href="https://doi.org/10.1073/pnas.1711842115">a 2018 study</a>, people represent just 0.01% of all living things by mass but have caused the loss of 83% of all wild mammals and half of all plants in our brief time on Earth. By annihilating nature, humankind might be losing out on new, powerful and life-altering techniques without having even imagined them.</p>
<p>[<em>Over 100,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p>
<p>After all, no one could have foreseen that the discovery of three groundbreaking processes derived from nature could change the way science is done.</p><img src="https://counter.theconversation.com/content/164459/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marc Zimmer received funding from NIH for his fluorescent protein research. </span></em></p>Three pioneering technologies have forever altered how researchers do their work and promise to revolutionize medicine, from correcting genetic disorders to treating degenerative brain diseases.Marc Zimmer, Professor of Chemistry, Connecticut CollegeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1604772021-05-17T10:22:02Z2021-05-17T10:22:02ZLife in the deep freeze – the revolution that changed our view of glaciers forever<figure><img src="https://images.theconversation.com/files/399492/original/file-20210507-17-1dedwyb.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5615%2C3741&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/perito-moreno-glacier-located-los-glaciares-599713124">Saiko3p/Shutterstock</a></span></figcaption></figure><p>I’ve been fascinated by glaciers since I was 14, when geography textbooks taught me about strange rivers of ice that crept down yawning valleys like giant serpents stalking their next meal. That kernel of wonder has carried me through a career of more than 25 years. I’ve travelled to the world’s peaks and its poles to see over 20 glaciers. Yet, when I first started out as a researcher in the early 1990s, we were convinced glaciers were lifeless deserts.</p>
<p>Then in 1999, <a href="https://pubs.geoscienceworld.org/gsa/geology/article-abstract/27/2/107/207041/Widespread-bacterial-populations-at-glacier-beds?redirectedFrom=fulltext">Professor Martin Sharp and colleagues</a> discovered bacteria living beneath the Haut Glacier d’Arolla in Switzerland. It seemed that glaciers, like the soil or our stomachs, had their own community of microbes, their own microbiome. Since then, we’ve found microorganisms just about everywhere within glaciers, transforming what we thought were sterile wastelands into vibrant ecosystems. </p>
<p>So what’s all that glacier life doing? These life forms may be invisible to the naked eye, but they can control how fast glaciers melt – and may even influence the global climate.</p>
<h2>The glacier microbiome</h2>
<p>Just like people, glacier microbes modify their homes. When I first saw the melting fringes of Greenland’s vast ice sheet, it looked as if a dust storm had scattered a vast blanket of dirt on the ice. Our team later discovered the dirt included extensive mats of <a href="https://www.nature.com/articles/ismej2012107">glacier algae</a>. These microscopic plant-like organisms contain <a href="https://academic.oup.com/femsec/article/94/3/fiy025/4850643">pigments</a> to help them harvest the Sun’s rays and protect them from harsh UV radiation. By coating the melting ice surface, they darken it, ensuring the ice absorbs more sunlight which causes more of it to melt. In western Greenland, <a href="https://tc.copernicus.org/articles/14/309/2020/">more than 10%</a> of the summer ice melt is caused by algae.</p>
<figure class="align-center ">
<img alt="Bright blue glacier ice on rocky terrain." src="https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&rect=0%2C0%2C3072%2C2304&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399491/original/file-20210507-15-1h0xzv6.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The margin of Engabreen glacier, Norway.</span>
<span class="attribution"><span class="source">Grzegorz Lis</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Again, just like us, microbes extract things from their environment to survive. The murky depths of glaciers are among the most challenging habitats for life on Earth. Microbes called <a href="https://aem.asm.org/content/80/19/6146">chemolithotrophs</a> – from the Greek meaning “eaters of rock” – survive here without light and get their energy from breaking down rock, releasing vital nutrients like iron, phosphorous and silicon to the meltwater. </p>
<p><a href="https://www.geochemicalperspectivesletters.org/article1510/">Rivers</a> and <a href="https://geochemicaltransactions.biomedcentral.com/articles/10.1186/1467-4866-9-7">icebergs</a> carry these nutrients to the ocean where they sustain the plant-like phytoplankton – the base of marine food webs which ultimately feed entire ecosystems, from microscopic animals, to fish and even whales. <a href="https://bg.copernicus.org/articles/11/2635/2014/bg-11-2635-2014.html">Models</a> and <a href="https://www.nature.com/articles/ngeo2633">satellite</a> observations show a lot of the photosynthesis in the iron-starved Southern Ocean could be sustained by rusty icebergs and meltwaters, which contain iron unlocked by glacier microbes. Recent evidence suggests something similar occurs off <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL073583">west</a> and <a href="https://www.nature.com/articles/s41598-019-53723-z">east</a> Greenland too.</p>
<figure class="align-center ">
<img alt="A microscope image depicting chains of brown rectangular cells." src="https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399503/original/file-20210507-19-196z49x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Glacier algae from the Greenland ice sheet.</span>
<span class="attribution"><span class="source">Chris Williamson</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But glacier bugs also produce waste, the most worrying of which is the greenhouse gas methane. When ice sheets grow, they bury <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GB002951">old soils and sediments</a>, all sources of carbon and the building blocks for earthly life. We think there could be thousands of billions of tonnes of <a href="https://www.nature.com/articles/nature11374">carbon buried beneath ice sheets</a> – potentially more than <a href="https://bg.copernicus.org/articles/11/6573/2014/">Arctic permafrost</a>. But who can use it in the oxygen-starved belly of an ice sheet? One type of microbe that flourishes here is <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02763.x">the methanogen</a> (meaning “methane maker”), which also thrives in landfill sites and rice paddies.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A waterfall at the edge of a glacier." src="https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=896&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=896&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=896&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1126&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1126&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399489/original/file-20210507-15-tbe32n.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1126&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leverett Glacier’s wild river, Greenland.</span>
<span class="attribution"><span class="source">Jemma Wadham</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Some methane produced by methanogens escapes in meltwaters flowing from the ice sheet edges. The clever thing about microbial communities, though, is that one microbe’s waste is another’s food. We humans could learn a lot from them about recycling. Some methane beneath glaciers is consumed by bacteria called methanotrophs (methane eaters) which generate energy by converting it to carbon dioxide. They have been detected in <a href="https://www.nature.com/articles/ismej201459">Greenlandic glaciers</a>, but most notably in <a href="https://www.nature.com/articles/ngeo2992?WT.feed_name=subjects_climate-sciences">Lake Whillans</a> beneath the West Antarctic Ice Sheet. Here, bacteria have years to chomp on the gas, and almost all of the methane produced in the lake is eaten – a good thing for the climate, since carbon dioxide is 80 times less potent as a greenhouse gas when measured over two decades.</p>
<p>We’re not sure this happens everywhere though. Fast-flowing rivers emerging from the Greenland Ice Sheet are <a href="https://www.nature.com/articles/s41586-018-0800-0">super-saturated with microbial methane</a> because there just isn’t enough time for the methanotrophs to get to work. Will melting glaciers release stored methane faster than these bacteria can convert it?</p>
<p>Within the thick interior of ice sheets, scientists worry that there may be vast reserves of methane. The cold and high pressure here mean that it may be trapped in its solid form, methane hydrate (or clathrate), which is stable unless the ice retreats and thins. <a href="https://science.sciencemag.org/content/356/6341/948.abstract">It happened before</a> and it could happen again.</p>
<h2>Waking the sleeping giant</h2>
<p>Despite the climate crisis, when I spend time around glaciers I’m not surprised by their continuing vitality. As I amble up to the gently sloping snout of a glacier – traversing its rubbly lunar-like fore-fields – I often feel like I’m approaching the hulk of an enormous creature. Sleeping or seemingly dormant, the evidence of its last meal is clear from the mass of tawny-coloured rocks, pebbles and boulders strewn around its edges – a tantalising record of where it once rested when the climate was cooler.</p>
<p>As I get closer, I catch the sound of the glacier’s roaring chocolate meltwaters as they explode through an ice cave, punctuated by a cascade of bangs and booms as moving ice collapses into hollow melt channels below. The winds off the ice play ominously in my ears, like the whisper of the beast, a warning: “You’re on my land now.”</p>
<figure class="align-center ">
<img alt="The author inside a giant icy chasm within a glacier." src="https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399486/original/file-20210507-21-if33gy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Exploring a frozen melt channel of the Finsterwalderbeeen glacier in Svalbard.</span>
<span class="attribution"><span class="source">Jon Ove Hagen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This sense of aliveness with glaciers changes everything. Resident microbes connect these hulking frozen masses with the Earth’s carbon cycle, ecosystems and climate. How will these connections change if we take away the frigid homes of our tiny glacier dwellers? These creatures may be microscopic, but the effects of their industry span entire continents and oceans.</p>
<p>After a period of uncertainty in my own life, which involved the removal of a satsuma-sized growth in my brain, I felt compelled to tell the story of glaciers to a wider audience. My book, <a href="https://www.penguin.co.uk/books/319/319535/ice-rivers/9780241467688.html">Ice Rivers</a>, is the result. I hope the memoir raises awareness of the dramatic changes that threaten glaciers – unless we act now.</p><img src="https://counter.theconversation.com/content/160477/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jemma is Director of the Cabot Institute for the Environment at the University of Bristol, and holds an adjunct professorship at UiT, the Arctic University of Norway. She has received grant funding in the past from the Engineering and Physics Research Council UK, Natural Environment Research Council UK, the Leverhulme Trust, The Royal Society, The British Council, EU Horizon 2020 and the Research Council of Norway. She is the author of Ice Rivers (Allen Lane-Penguin Press, Jemma Wadham Ltd). </span></em></p>Glaciers aren’t sterile wastelands – they’re chock-full of microscopic life.Jemma Wadham, Professor of Glaciology, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1603122021-05-05T14:18:48Z2021-05-05T14:18:48ZHow the trees in your local park help protect you from disease<figure><img src="https://images.theconversation.com/files/398914/original/file-20210505-13-kkpw5a.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5470%2C3677&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bench-under-tree-royal-botanic-gardens-136458284">Dmitry Naumov/Shutterstock</a></span></figcaption></figure><p>On your next visit to the park, try and count all the different species you can see. Away from the closely mown grass, you might spot wildflowers attended by pollinating insects, like bees, wasps and hoverflies. Overhead there are the gnarled branches of mature trees, some of which will have lived for hundreds of years, providing food and refuge for generations of fungi and insects. </p>
<p>You may find yourself immersed in the chorus of songbirds fervently competing for mates. There will undoubtedly be fleet-footed mammals scurrying in the bushes and amphibians hiding under logs. </p>
<p>But there’s also another world of wildlife floating all around you. This is the biodiversity that we can’t see with the naked eye – the secret life of the air we breathe.</p>
<h2>Invisible nature</h2>
<p>The air is full of microscopic life forms: dense clouds of bacteria, tiny fungi and algae which surround us. There are single-celled organisms called <a href="https://www.sciencedirect.com/science/article/pii/S0160412021001768">protozoans</a> and vast quantities of viruses, moss spores and plant pollen. There may even be a few microscopic moss-dwelling animals <a href="https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/abs/im-kinchin-the-biology-of-tardigrades-xi-186p-london-portland-press-1994/C39981B58166F8CAE6F4374AF1361374">called tardigrades</a>, also known as water bears or moss piglets because of their mammal-like appearance (under the microscope, at least).</p>
<figure class="align-center ">
<img alt="An electron microscope image of a tardigrade." src="https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=460&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=460&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=460&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=578&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=578&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398866/original/file-20210505-23-16ahf62.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=578&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tardigrades are eight-legged micro-animals that are found everywhere in the Earth’s biosphere.</span>
<span class="attribution"><a class="source" href="https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0045682.g001">Schokraie et al. (2012)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Humans are bombarded by all these tiny organisms on a daily basis. Studies have shown that up to a million microbial cells can be found in a single <a href="https://ehp.niehs.nih.gov/doi/full/10.1289/EHP7807">cubic metre of air</a>, and people can inhale a whopping <a href="https://bg.copernicus.org/articles/4/1127/2007/">100 million bacteria</a> each day.</p>
<p>But where does all this invisible life come from? And what does our exposure to it mean for our health? Together with colleagues, we set out to discover the kinds of microbes people are likely to encounter during walks in urban parks.</p>
<p>Our recent study in <a href="https://www.nature.com/articles/s41598-021-89065-y">Scientific Reports</a> suggested that many of the life forms floating in the air actually originate in the soil beneath our feet. This makes a lot of sense. Soil is arguably the most biodiverse habitat on Earth, and a single gram of it can contain more microbes than there are <a href="https://www.nature.com/scitable/knowledge/library/the-rhizosphere-roots-soil-and-67500617/">humans on the planet</a>.</p>
<p>Microbes are incredibly light, so they become airborne really easily and are carried far and wide on <a href="https://apsjournals.apsnet.org/doi/pdf/10.1094/9780890545430.fm">the wind</a>. They can be lifted from the soil in <a href="https://www.nature.com/articles/ncomms14668">air bubbles</a> that form in raindrops and clump together on <a href="https://pubmed.ncbi.nlm.nih.gov/33902752/">dust particles</a> which fall from the atmosphere.</p>
<figure class="align-center ">
<img alt="A petri dish with pink and orange bacteria growing on nutrient agar." src="https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398912/original/file-20210505-15-1t7ufv7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Soil microbes grown in a petri dish.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/top-view-soil-microorganisms-nutrient-agar-1351225445">Sarawut Chainawarat/Shutterstock</a></span>
</figcaption>
</figure>
<p>Our study showed that distinct layers of bacteria <a href="https://ehp.niehs.nih.gov/doi/full/10.1289/EHP7807">form in the air</a>, with different species and quantities of microbes occurring at different heights. At the average head-height of a standing adult, there were fewer but also different kinds of bacteria compared with those in the air lower down at the head height of a child or sitting adult.</p>
<p>This means that we may be exposed to different kinds of microbes – some good for us, some bad – depending on our height and posture. Exposure to lots of different types of microbial life, particularly in childhood, is generally considered to be a good thing, because it <a href="https://advances.sciencemag.org/content/6/42/eaba2578.full">allows our immune systems</a> to build up a strong army of cells that protect us from pathogens. The greater number of microbial species we detected closer to the ground could be vital in ensuring children develop robust immunity later in life. </p>
<p>But it also matters which environments we spend time in. After collecting 135 samples, we found that the air in the wooded areas of an urban park near Adelaide in Australia contained more bacterial species but fewer potential human pathogens than nearby sports fields. Trees appear to filter the microbial communities in a given airspace, reducing the risk of exposure to microbes that cause disease. Because trees also seem to increase microbial diversity in the air, allowing more of them to grow in urban areas could provide an important health benefit by enhancing our immune systems.</p>
<figure class="align-center ">
<img alt="A neatly mown football field in a public park." src="https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398915/original/file-20210505-21-vlf689.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fewer trees meant more pathogens in the recent study.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/background-public-park-soccer-field-sideline-624204398">CLS Digital Arts/Shutterstock</a></span>
</figcaption>
</figure>
<p>This wouldn’t only benefit human health. Although we can’t see the microbes and the other members of the microscopic world around us, they’re fundamental to the <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2015.01097/full">proper functioning</a> of ecosystems, plant health and communication <a href="https://academic.oup.com/aobpla/article/doi/10.1093/aobpla/plv050/201398?login=true">(yes, plants talk to each other)</a>, and even <a href="https://www.nature.com/articles/s41579-019-0222-5">climate regulation</a>. </p>
<p>We still know relatively little about the unseen life in the air we breathe, but our <a href="https://www.nature.com/articles/s41598-021-89065-y">preliminary findings</a> reveal a few of their secrets. We would be wise to learn and encourage them in the <a href="https://www.preprints.org/manuscript/202104.0560/v1">important roles they play</a>.</p><img src="https://counter.theconversation.com/content/160312/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jake M. Robinson receives funding from the Economic and Social Research Council (ESRC). Jake is a board member of inVIVO Planetary Health and on the Healthy Urban Microbiome Initiative (HUMI) development team. </span></em></p><p class="fine-print"><em><span>Martin Breed receives funding from the Australian Research Council and co-leads the Healthy Urban Microbiome Initiative (HUMI).</span></em></p><p class="fine-print"><em><span>Ross Cameron does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Invisible to the eye, the microbial life in the air around us can vary depending on our environment.Jake M Robinson, Ecologist and PhD Researcher, Department of Landscape, University of SheffieldMartin Breed, Lecturer in Biology, Flinders UniversityRoss Cameron, Senior Lecturer, Department of Landscape Architecture, University of SheffieldLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1585682021-04-08T17:48:03Z2021-04-08T17:48:03ZWater being pumped into Tampa Bay could cause a massive algae bloom, putting fragile manatee and fish habitats at risk<figure><img src="https://images.theconversation.com/files/393869/original/file-20210407-17-brnypt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tampa Bay's sea grass meadows need sunlight to thrive. Algae blooms block that light and can be toxic to marine life.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/btsAoomBCeM">Joe Whalen Caulerpa/Tampa Bay Estuary Program via Unsplash</a></span></figcaption></figure><p>Millions of gallons of water laced with fertilizer ingredients are being pumped into Florida’s Tampa Bay from a <a href="https://protectingfloridatogether.gov/PineyPointUpdate">leaking reservoir</a> at an abandoned phosphate plant at Piney Point. As the water spreads into the bay, it carries phosphorus and nitrogen – nutrients that under the right conditions can <a href="https://www.noaa.gov/what-is-harmful-algal-bloom">fuel dangerous algae blooms</a> that can suffocate sea grass beds and kill fish, dolphins and manatees.</p>
<p>It’s the kind of risk no one wants to see, but officials believed the other options were worse.</p>
<p>About 300 homes sit downstream from the 480-million-gallon reservoir, which began leaking in late March 2021. State officials determined that <a href="https://protectingfloridatogether.gov/PineyPointUpdate">pumping out the water</a> was the only way to prevent the reservoir’s walls from collapsing. They decided the safest location for all that water would be out <a href="https://www.usatoday.com/in-depth/news/2021/04/05/piney-point-florida-reservoir-breach-flood-tampa-bay-palmetto-evacuation/7088307002/">through Port Manatee</a> and into the bay.</p>
<p>Florida’s coast is dotted with <a href="https://www.fws.gov/southeast/gulf-restoration/next-steps/focal-area/tampa-bay/">fragile marine sanctuaries</a> and <a href="https://www.pewtrusts.org/en/research-and-analysis/issue-briefs/2019/10/healthy-seagrass-forms-underwater-meadows-that-harbor-diverse-marine-life">sea grass beds</a> that help nurture the state’s thriving <a href="https://coast.noaa.gov/enowexplorer/#/employment/total/2017/12081">marine and tourism economy</a>. Those near Port Manatee now face a risk of algal blooms over the next few weeks. Once algae blooms get started, little can be done to clean them up.</p>
<p>The phosphate mining industry around Tampa is just one source of nutrients that can fuel dangerous algae blooms, which I study <a href="https://people.miami.edu/profile/l.brand@miami.edu#panelResearch">as a marine biologist</a>. The sugarcane industry, cattle ranches, dairy farms and citrus groves <a href="https://iwaponline.com/wp/article/20/5/919/41575">all release</a> <a href="http://doi.org/10.1016/j.hal.2006.08.005">nutrients</a> that often flow into rivers and eventually into bays and the ocean. Sewage is another problem – Miami and Fort Lauderdale, for example, have <a href="https://www.theguardian.com/us-news/2020/sep/10/florida-sewage-spill-waterways-infrastructure">old sewage treatment systems with frequent pipe breaks</a> that leak sewage into canals and coastal waters.</p>
<p>All can <a href="https://iwaponline.com/wp/article/20/5/919/41575">fuel harmful algal blooms</a> that harm marine life and people. Overall, blooms are <a href="https://www.jstor.org/stable/24897842">getting worse locally</a> and <a href="https://doi.org/10.1038/s41586-019-1648-7">globally</a>. </p>
<figure class="align-center ">
<img alt="Two manatees swimming underwater" src="https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/394065/original/file-20210408-21-19rm9jk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Red tide in recent years has killed large numbers of Florida’s manatees, a threatened species.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/usfwsendsp/5104977481/">David Hinkel/U.S. Fish and Wildlife Service</a></span>
</figcaption>
</figure>
<h2>The problem with algae blooms</h2>
<p>Just down the coast from Port Manatee, the next three counties to the south have had algae blooms in recent weeks, including red tide, which <a href="https://doi.org/10.1016/j.hal.2009.08.005">produces a neurotoxin</a> that feels like pepper spray if you breathe it in. <em>Karenia brevis</em>, a dinoflagellate, is the organism in red tide and produces the toxin.</p>
<p>This part of Florida’s Gulf Coast is a <a href="https://doi.org/10.1016/j.hal.2006.08.005">hot spot for red tide</a>, often fueled by agricultural runoff. A persistent red tide in 2017 and 2018 <a href="https://wusfnews.wusf.usf.edu/2020-01-02/2019-was-not-a-good-year-for-manatees-boat-strikes-and-red-tide-took-a-toll">killed at least 177 manatees</a> and left a trail of dead fish along the coast and into Tampa Bay. If the coastal currents carry today’s red tide father north and into Tampa Bay, the toxic algae could thrive on the nutrients from Piney Point. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two maps with dots showing locations of reports." src="https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=270&fit=crop&dpr=1 600w, https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=270&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=270&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/394043/original/file-20210408-13-1dg5rae.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A map shows red tide reports just south of Tampa Bay.</span>
<span class="attribution"><a class="source" href="https://myfwc.com/research/redtide/statewide/">Florida Fish and Wildlife Conservation Commission</a></span>
</figcaption>
</figure>
<p>Even blooms that are not toxic are <a href="https://www.noaa.gov/what-is-harmful-algal-bloom">still dangerous to ecosystems</a>. They cloud the water, cutting off light and killing the plants below. A large enough bloom can also reduce oxygen in the water. A lack of oxygen can kill off everything in the water, including the fish.</p>
<p>This part of Florida has extensive sea grass meadows, <a href="https://floridadep.gov/rcp/seagrass">about 2.2 million acres (8.9 billion square meters) in all</a>, which are important habitat for lots of species and serve as nurseries for shrimp, crabs and fish. Scientists have argued that sea grass is also a <a href="https://doi.org/10.1038/ngeo1477">major carbon sink</a> – the grass sucks up carbon and pumps it down into the sediments.</p>
<p>Once the nutrients are in a large body of water, there isn’t much that can be done to stop algae growth. Killing the algae would only release the nutrients again, putting the bay back where it started. Algae blooms can remain a problem for years, finally declining when a predator population develops to eats them, a viral disease spreads through the bloom or strong currents and mixing disperse the bloom.</p>
<h2>Agriculture runoff poses risks to marine life</h2>
<p>The phosphate mining industry around Tampa is a large source of nutrient-rich waste. On average, <a href="https://www.epa.gov/radiation/tenorm-fertilizer-and-fertilizer-production-wastes#fertilizer">more than 5 tons</a> of phosphogypsum waste are produced for every ton of phosphoric acid created for fertilizer. In Florida, that adds up to <a href="https://fipr.floridapoly.edu/about-us/phosphate-primer/phosphogypsum-stacks.php">over 1 billion tons</a> of radioactive waste material that can’t be used, so it’s stacked up and turned into reservoirs like the one now leaking at Piney Point.</p>
<p>The reservoirs are obvious in satellite photos of the region, and they can be highly acidic. To get the phosphate out of the minerals, the industry uses sulfuric acid, and it leaves behind a highly acid wastewater. There have been at least <a href="https://www.theguardian.com/us-news/2016/sep/17/florida-sinkhole-wastewater-leak-drinking-water">two cases where it ate through the limestone below a reservoir</a>, creating huge sinkholes hundreds of feet deep and draining wastewater into the aquifer.</p>
<p>Since <a href="https://protectingfloridatogether.gov/PineyPointUpdate">saltwater had previously been pumped into</a> the Piney Point reservoir, acidity is less of an issue. That’s because the seawater would buffer the pH. There is some radioactivity, but <a href="https://protectingfloridatogether.gov/PineyPointUpdate">only slightly above regulatory standards</a>, according to state Department of Environmental Protection, and probably not much of a health hazard.</p>
<p>But the nutrients are a risk. In 2004, water releases from the Piney Point reservoir <a href="https://www.wtsp.com/article/news/local/piney-point-dumping-causes-algae-bloom-in-bishop-harbor/67-396514258">contributed to an algae bloom</a> in Bishop Harbor, just south of the current release site. In 2011, it released over <a href="https://thebradentontimes.com/piney-point-a-retrospective-p6328-158.htm">170 million gallons</a> into Bishop Harbor again after a liner broke.</p>
<p><iframe id="J5e50" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/J5e50/5/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Another significant source of algae-feeding nutrients is agriculture, particularly cattle ranching and the sugarcane industry. Nutrient runoff from cattle ranches and dairy farms north of Lake Okeechobee end up in the lake. South of the lake, much of the <a href="https://doi.org/10.4000/miranda.2881">northern third of the Everglades</a> was converted to sugarcane farms, and those fields back-pumped runoff into the lake for decades until the state started cracking down in the 1980s. Their legacy nutrients are still in the lake. </p>
<p>The nutrient-rich water in the lake then pours down the Caloosahatchee River and into the Gulf of Mexico near Fort Myers, south of Tampa. That’s likely feeding the current red tide off the mouth of the Caloosahatchee River.</p>
<p>When water from the Everglades region’s agriculture is pumped south instead, huge blooms tend to appear in Florida Bay at the southern tip of the state. Some scientists believe it <a href="http://doi.org/10.1007/s00227-019-3538-9">may be damaging coral reefs</a> there, though there’s debate about it. During times that flow of water from the farms increased, reefs throughout the Florida Keys have been harmed. Those reefs have become overgrown with algae.</p>
<p>With the current red tide, the coastal currents have carried it north as far as Sarasota already. If they carry it farther north, it will run into the Piney Point area.</p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/158568/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Larry Brand has received funding from the National Science Foundation, National Institutes of Health, Environmental Protection Agency, National Oceanic and Atmospheric Association, National Park Service, Department of Energy, Office of Naval Research, Army Corps of Engineers, Florida Department of Health, Dade County Department of Environmental Resources Management, Cove Point Foundation, and Hoover Foundation. </span></em></p>Harmful algae blooms are an increasing problem in Florida. Once nutrients are in the water to fuel them, little can be done to stop the growth, and the results can be devastating for marine life.Larry Brand, Professor of Marine Biology and Ecology, University of MiamiLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1542662021-03-01T19:10:42Z2021-03-01T19:10:42ZLife on the hidden doughnuts of the Great Barrier Reef is also threatened by climate change<figure><img src="https://images.theconversation.com/files/386318/original/file-20210225-13-1xhk1ej.jpg?ixlib=rb-1.1.0&rect=0%2C155%2C4448%2C3219&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A sea cucumber living on the Great Barrier Reef inter-reef seafloor.</span> <span class="attribution"><span class="source">Kent Holmes/Nature Ecology and Evolution</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Mention the Great Barrier Reef, and most people think of the rich beauty and colour of corals, fish and other sea life that are increasingly <a href="https://www.gbrmpa.gov.au/our-work/threats-to-the-reef/climate-change">threatened by climate change</a>.</p>
<p>But there is another part of the Great Barrier Reef that until recently was largely hidden and under-explored. </p>
<p>In the northern section of the Great Barrier Reef Marine Park there are large <em>Halimeda</em> algal habitats called <a href="https://link.springer.com/article/10.1007%2FBF00302010" title="Halimeda bioherms of the northern Great Barrier Reef">bioherms</a> (also known as doughnuts because of their shape).</p>
<p>They are constructed by a type of algae (<em>Halimeda</em>) with a limestone skeleton. The tops of the bioherms are carpeted by a living meadow of the algae, yet much of the plant community includes other types of green, red and brown algae and some seagrasses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A type of green seaweed." src="https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382110/original/file-20210203-21-qmsn6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Halimeda</em> is a genus of green macroalgae (seaweed).</span>
<span class="attribution"><span class="source">Mardi McNeil</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The bioherms cover an area greater than <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/dep2.122" title="Morphotype differentiation in the Great Barrier Reef Halimeda bioherm carbonate factory: Internal architecture and surface geomorphometrics">6,000km²</a>, more than twice the area of shallow coral reefs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Several maps showing the location of the _Halimeda_ bioherms." src="https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385990/original/file-20210223-15-cogh30.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The distribution of <em>Halimeda</em> bioherms in the Great Barrier Reef.</span>
<span class="attribution"><a class="source" href="https://figshare.com/articles/figure/Distribution_of_mapped_Halimeda_bioherms_-_Great_Barrier_Reef/7506251">Figshare/Mardi McNeil</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Scientists have known <a href="https://link.springer.com/article/10.1007/BF02395280" title="Halimeda biomass, growth rates and sediment generation on reefs in the central great barrier reef province">for decades</a> of this unusual inter-reef seafloor habitat that lies between the coast and the outer barrier reefs. But they’ve never investigated the diversity of marine life that lives there, until now.</p>
<p>In a new study published today in <a href="https://dx.doi.org/10.1038/s41559-021-01400-8" title="Inter-reef Halimeda algal habitats within the Great Barrier Reef support a distinct biotic community and high biodiversity">Nature Ecology and Evolution</a>, scientists examined the community of plants and animals that inhabit these unique areas. </p>
<h2>Let’s go deeper</h2>
<p>Most studies of tropical marine biodiversity come from shallow <a href="https://www.mdpi.com/1424-2818/10/1/1/htm" title="Some Implications of High Biodiversity for Management of Tropical Marine Ecosystems—An Australian Perspective">coastal and coral reef habitats</a>. We know a great deal about the biodiversity of these parts of the Great Barrier Reef.</p>
<p>But beyond the vision of scuba divers, deeper inter-reef habitats on the shelf, such as the bioherms, have been largely under-explored.</p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/gene-editing-is-revealing-how-corals-respond-to-warming-waters-it-could-transform-how-we-manage-our-reefs-143444">Gene editing is revealing how corals respond to warming waters. It could transform how we manage our reefs</a>
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<p>In our study, we used a <a href="https://www.marine.csiro.au/ipt/resource?r=csiro_gbr_sbd" title="CSIRO - Great Barrier Reef seabed biodiversity study 2003-2006">dataset</a> of all the plants and animals recorded from the bioherms and surrounding seafloor habitats. The data came from the <a href="http://www.frdc.com.au/Archived-Reports/FRDC%20Projects/2003-021-DLD.pdf">Seabed Biodiversity Project</a>, a large study published back in 2007 of the inter-reef biodiversity in the Great Barrier Reef World Heritage Area.</p>
<p>What we found was surprising. An exceptional diversity of marine life and a distinct community was found to be living on the bioherms.</p>
<h2>A diverse community</h2>
<p>The biodiversity of marine life was up to 76% higher on the bioherms than the surrounding inter-reef habitats. Species richness was especially high for plants and invertebrates.</p>
<p>The average number of fish species per site was about the same in both <em>Halimeda</em> and non-<em>Halimeda</em> habitats. In total, 265 species of fish were observed in the bioherms, including sharks and rays.</p>
<p>Overall, more than 1,200 species of animals were recorded from the bioherms. The majority of these (78%) are invertebrates.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A feather star invertebrate." src="https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382112/original/file-20210203-13-128ayp4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most of the animals living on the <em>Halimeda</em> bioherms are invertebrates, such as this feather star.</span>
<span class="attribution"><span class="source">Mardi McNeil</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A distinct community</h2>
<p>The composition of plant and animal communities on the bioherms was also distinctly different to the surrounding inter-reef areas. </p>
<p>Some 40% of bioherm species were unique to that habitat in the study area. The community included many sponges, snails and slugs, crabs and shrimps, brittle stars, sea urchins and sea cucumbers. </p>
<p>The fish community on the bioherms was also distinct from surrounding habitats. The <a href="https://fishesofaustralia.net.au/home/species/261">two-spot wrasse</a>, <a href="https://fishesofaustralia.net.au/home/species/2460">threadfin emperor</a> and <a href="https://fishesofaustralia.net.au/home/species/315">black-banded damselfish</a> were particularly common.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small black fish with a yellow tail and a white band near its neck." src="https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/386068/original/file-20210224-13-10p7wju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A yellowtail angelfish (<em>Chaetodontoplus meredithi</em>) seen in coral waters of the Great Barrier Reef.</span>
<span class="attribution"><a class="source" href="https://fishesofaustralia.net.au/home/species/2503">Sascha Schultz/iNaturalist.org/FishofAustralia</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>Most interesting about the bioherm fish community was the occurrence of some species such as the <a href="https://fishesofaustralia.net.au/home/species/2503">yellowtail angelfish</a> generally thought to live mostly on coral reefs. Some of these reef-associated fishes have been increasingly observed in <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/faf.12383" title="Beyond the reef: The widespread use of non‐reef habitats by coral reef fishes">a range of non-reef habitats</a>.</p>
<p>These multi-habitat users may be using the bioherms for shelter, feeding, spawning or as nursery grounds. Understanding the connections between shallow coral reefs and deeper bioherms is important to better understand how the reef and inter-reef habitats function.</p>
<h2>An unusual habitat</h2>
<p>The <em>Halimeda</em> bioherms are arguably the <a href="https://www.abc.net.au/news/2016-09-01/new-reef-discovered-near-great-barrier-reef/7806580">weirdest habitat</a> in the Great Barrier Reef.</p>
<p>Recent high-resolution <a href="https://link.springer.com/article/10.1007/s00338-016-1492-2" title="New constraints on the spatial distribution and morphology of the Halimeda bioherms of the Great Barrier Reef, Australia">seafloor mapping</a> using <a href="https://www.deepreef.org/technology/52-lidar.html">airborne lasers</a> revealed the bioherms form a seafloor that looks like fields of giant doughnuts 20 metres high and 200 metres across.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9e9H8jQZUWg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The doughnuts are the connected circles on the seafloor in the yellow/green bioherm part. They look quite small but each circle is about 200 metres across.</span></figcaption>
</figure>
<p>The tops of the bioherms lie some <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/dep2.122" title="Morphotype differentiation in the Great Barrier Reef Halimeda bioherm carbonate factory: Internal architecture and surface geomorphometrics">25-30 metres below the surface</a>, so can’t be seen from boats passing over. </p>
<p>Deeper water and the remote location has meant the bioherms have been mostly invisible to marine biologists that work on the nearby shallow coral reefs. </p>
<h2>Under threat from climate change</h2>
<p>We are only just beginning to understand the importance of <em>Halimeda</em> bioherms as a habitat to support biodiversity in the Great Barrier Reef. </p>
<p>But just as the rest of the Great Barrier Reef is likely to be impacted by the effects of <a href="https://www.nature.com/articles/s41586-018-0041-2" title="Global warming transforms coral reef assemblages">climate change</a>, so too are the bioherms. </p>
<p>Potential threats to the bioherms include <a href="https://link.springer.com/article/10.1007/s00338-015-1377-9" title="Increased temperature mitigates the effects of ocean acidification in calcified green algae (Halimeda spp)">marine heating</a>, <a href="https://www.int-res.com/abstracts/meps/v440/p67-78" title="Species-specific consequences of ocean acidification for the calcareous tropical green algae Halimeda">ocean acidification</a> and changes to <a href="https://www.gbrmpa.gov.au/our-work/threats-to-the-reef/climate-change/ocean-currents">circulation patterns</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/under-the-moonlight-a-little-light-and-shade-helps-larval-fish-to-grow-at-night-153192">Under the moonlight: a little light and shade helps larval fish to grow at night</a>
</strong>
</em>
</p>
<hr>
<p>It has been more than 15 years since the inter-reef Seabed Biodiversity Project. The five-yearly Great Barrier Reef <a href="https://www.gbrmpa.gov.au/our-work/outlook-report-2019">Outlook Report</a> says little is known about any ecological trends in the bioherm habitat.</p>
<p>Our new study provides a baseline of the biodiversity of <em>Halimeda</em> bioherms at a single point in time. But questions remain about the present state of this ecosystem and its resilience on short and long-term physical and biological cycles.</p>
<p><a href="https://www.aims.gov.au/docs/research/monitoring/reef/reef-monitoring.html">Long-term monitoring</a> of these unique and hidden habitats is critical to more fully understand the overall health of the Great Barrier Reef.</p><img src="https://counter.theconversation.com/content/154266/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mardi McNeil has previously received funding from the National Geographic Society, the NSW Foundation for Parks and Wildlife, and the Great Barrier Reef Marine Park Authority for research on the habitat potential of Halimeda bioherms.</span></em></p><p class="fine-print"><em><span>Andrew Hoey receives funding from the Australian Research Council and Department of Agriculture, Water, and the Environment. He is a councillor of the Australian Coral Reef Society, and member of the Coral Sea Marine Park Advisory Committee. </span></em></p><p class="fine-print"><em><span>Jody Webster has previously received funding from the National Geographic Society for research on the Halimeda bioherms.</span></em></p><p class="fine-print"><em><span>Luke Nothdurft receives funding from the Ian Potter Foundation.</span></em></p>We are only just beginning to understand the importance of this deep and hidden area of the inter-reef that supports a rich diversity of marine life.Mardi McNeil, Postdoctoral researcher, Queensland University of TechnologyAndrew Hoey, Senior Research Fellow, James Cook UniversityJody Webster, Professor of Marine Geoscience, University of SydneyLuke Nothdurft, Senior Lecturer - Earth Science, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1318832020-04-29T11:54:24Z2020-04-29T11:54:24ZClimate change threatens drinking water quality across the Great Lakes<figure><img src="https://images.theconversation.com/files/324413/original/file-20200331-65499-9oonn5.jpg?ixlib=rb-1.1.0&rect=10%2C7%2C1715%2C1285&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Harmful algal bloom in Lake Erie, Sept. 4, 2009.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/ejuTXG">NOAA/Flickr</a></span></figcaption></figure><p><em>This story is part of the Pulitzer Center’s nationwide Connected Coastlines reporting initiative. For more information, go to https://pulitzercenter.org/connected-coastlines-initiative.</em></p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=433&fit=crop&dpr=1 754w, https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=433&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/329833/original/file-20200422-47794-1362t1o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=433&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>“Do Not Drink/Do Not Boil” is not what anyone wants to hear about their city’s tap water. But the combined effects of climate change and degraded water quality could make such warnings more frequent across the Great Lakes region. </p>
<p>A preview occurred on July 31, 2014, when a nasty green slime – properly known as a harmful algal bloom, or HAB – developed in the <a href="https://www.glerl.noaa.gov/res/HABs_and_Hypoxia/lakeErieHABArchive/bulletin_2014-009.pdf">western basin of Lake Erie</a>. Before long it had overwhelmed the Toledo Water Intake Crib, which provides drinking water to nearly 500,000 people in and around the city. </p>
<p>Tests revealed that the algae was producing microcystin, a sometimes deadly liver toxin and suspected carcinogen. Unlike some other toxins, microcystin can’t be rendered harmless by boiling. So the city issued a “Do Not Drink/Do Not Boil” order that <a href="https://www.toledoblade.com/local/2014/08/03/Water-crisis-grips-area/stories/20140803090">set off a three-day crisis</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/324416/original/file-20200331-65503-cgil0n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The City of Toledo water intake crib surrounded by algae in Lake Erie, about 2.5 miles offshore, Aug. 3, 2014.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Lake-Erie-Algae/b1362d277b254cf1bd7b00266e80a396/5/0">AP Photo/Haraz N. Ghanbari</a></span>
</figcaption>
</figure>
<p>Local stores soon ran out of bottled water. Ohio’s governor declared a state of emergency, and the National Guard was called in to provide safe drinking water until the system could be flushed and treatment facilities brought back on line. </p>
<p>The culprit was a combination of high nutrient pollution – nitrogen and phosphorus, which stimulate the growth of algae – from sewage, agriculture and suburban runoff, and high water temperatures linked to climate change. This event showed that even in regions with resources as vast as the Great Lakes, water supplies are vulnerable to these kinds of man-made threats. </p>
<p>As Midwesterners working in the fields of <a href="https://scholar.google.com/citations?user=MEp4948AAAAJ&hl=en">urban environmental health</a> and <a href="https://scholar.google.com/citations?user=qMBuSe4AAAAJ&hl=en">climate and environmental science</a>, we believe more crises like Toledo’s could lie ahead if the region doesn’t address looming threats to drinking water quality.</p>
<h2>Vast and abused</h2>
<p>The Great Lakes together hold 20% of the world’s surface freshwater – more than enough to provide drinking water to <a href="https://www.glc.org/lakes/">over 48 million people</a> from Duluth to Chicago, Detroit, Cleveland and Toronto. But human impacts have severely harmed this precious and vital resource. </p>
<p>In 1970, after a century of urbanization and industrialization around the Great Lakes, water quality was severely degraded. Factories were allowed to dump waste into waterways rather than treating it. Inadequate sewer systems often sent raw sewage into rivers and lakes, fouling the water and causing algal blooms.</p>
<p>Problems like these helped spur two major steps in 1972: passage of the U.S. <a href="https://www.epa.gov/laws-regulations/history-clean-water-act">Clean Water Act</a>, and adoption of the <a href="https://binational.net/glwqa-aqegl/">Great Lakes Water Quality Agreement</a> between the United States and Canada. Since then, many industries have been cleaned up or shut down. Sewer systems are being redesigned, albeit slowly and at great cost. </p>
<p>The resulting cuts in nutrient and wastewater pollution have brought a quick decline in HABs – especially in Lake Erie, the Great Lake with the most densely populated shoreline. But new problems have emerged, due partly to shortcomings in those laws and agreements, combined with the growing effects of climate change.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/D4Nsp96zV-E?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Drinking water from the Great Lakes is in high demand.</span></figcaption>
</figure>
<h2>Warmer and wetter</h2>
<p>Climate change is <a href="http://glisa.umich.edu/gl-climate-factsheet-refs">profoundly altering many factors</a> that affect life in the Great Lakes region. The most immediate impacts of recent climate change have been on precipitation, lake levels and water temperatures. </p>
<p>Annual precipitation in the region has increased by about <a href="https://www.ncdc.noaa.gov/cag/regional/time-series/103/pcp/12/12/1895-2020?base_prd=true&begbaseyear=1901&endbaseyear=2000">5 inches over the past century</a>. Changes in the past five years alone – the <a href="https://www.nationalgeographic.com/environment/2019/02/2018-fourth-warmest-year-ever-noaa-nasa-reports/">hottest five years in recorded history</a> – have been particularly dramatic, with a series of extreme rainfall events bringing extremely high and <a href="https://theconversation.com/climate-change-is-driving-rapid-shifts-between-high-and-low-water-levels-on-the-great-lakes-118095">rapidly varying water levels</a> to the Great Lakes.</p>
<p>Record high precipitation in 2019 caused flooding, property damage and beachfront losses in a number of coastal communities. Precipitation in 2020 is projected to be equally high, if not higher. Some of this is due to natural variability, but certainly some is due to climate change. </p>
<p>Another clear impact of climate change is a general warming of all five Great Lakes, particularly in the springtime. The temperature increase is modest and varies from year to year and place to place, but is consistent overall with <a href="https://www.epa.gov/sites/production/files/2016-08/documents/print_great-lakes-2016.pdf">records of warming throughout the region</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1243262318722588673"}"></div></p>
<h2>More polluted runoff</h2>
<p>Some of these climate-related changes have converged with more direct human impacts to influence water quality in the Great Lakes. </p>
<p>Cleanup measures adopted back in the 1970s imposed stringent limits on large point sources of nutrient pollution, like wastewater and factories. But smaller “nonpoint” sources, such as fertilizer and other nutrients washing off farm fields and suburban lawns, were addressed through weaker, voluntary controls. These have since become major pollution sources. </p>
<p>Since the mid-1990s, climate-driven increases in precipitation have carried growing quantities of nutrient runoff into Lake Erie. This rising load has triggered <a href="https://theconversation.com/nutrient-pollution-voluntary-steps-are-failing-to-shrink-algae-blooms-and-dead-zones-81249">increasingly severe algal blooms</a>, comparable in some ways to the events of the 1970s. Toledo’s 2014 crisis was not an anomaly.</p>
<p>These blooms can make lake water smell and taste bad, and sometimes make it <a href="https://www.regions.noaa.gov/great-lakes/index.php/project/harmful-algal-blooms/">dangerous to drink</a>. They also have long-term impacts on the lakes’ ecosystems. They deplete oxygen, killing fish and spurring chemical processes that prime the waters of Lake Erie for <a href="https://doi.org/10.1016/j.scitotenv.2016.11.133">larger future blooms</a>. Low-oxygen water is more corrosive and can damage water pipes, causing poor taste or foul odors, and helps release trace metals that may also cause health problems.</p>
<p>So despite a half-century of advances, in many ways Great Lakes water quality is back to where it was in 1970, but with the added influence of a rapidly changing climate.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=347&fit=crop&dpr=1 600w, https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=347&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=347&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=436&fit=crop&dpr=1 754w, https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=436&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/324457/original/file-20200401-66109-1j9p4hc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=436&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Figure showing total phosphorus (TP) tributary loading to Lake St. Clair and the western Lake Erie in 2018 in metric tons per annum (MTA). Runoff from agricultural areas is the major source of nutrient loadings with about 70% from commercial fertilizer application and 30% from animal manure.</span>
<span class="attribution"><a class="source" href="https://www.ijc.org/en/green-without-envy-great-lakes-drown-excessive-nutrient-pollution">IJC</a></span>
</figcaption>
</figure>
<h2>Filtering runoff</h2>
<p>How can the region change course and build resilience into Great Lakes coastal communities? Thanks to a number of recent studies, including an intensive modeling analysis of <a href="https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1000&context=climatetr">future climate change in Indiana</a>, which serves as a proxy for most of the region, we have a pretty good picture of what the future could look like.</p>
<p>As one might guess, warming will continue. Summertime water temperatures are projected to rise by about another 5 degrees Fahrenheit by midcentury, <a href="https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1000&context=aquatictr">even if nations significantly reduce their greenhouse gas emissions</a>. This will cause further declines in water quality and negatively impact coastal ecosystems. </p>
<p>The analysis also projects an increase in extreme precipitation and runoff, <a href="https://doi.org/10.1007/s10584-019-02530-6">particularly in the winter</a> <a href="https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1000&context=climatetr">and spring</a>. These shifts will likely bring still more nutrient runoff, sediment contaminants and sewage overflows into coastal zones, even if surrounding states hold the actual quantities of these nutrients steady. More contaminants, coupled with higher temperatures, can trigger algal blooms that threaten water supplies. </p>
<p>But recent success stories point to strategies for tackling these problems, at least at the local and regional levels.</p>
<p>A number of large infrastructure projects are currently underway to improve stormwater management and municipal sewer systems, so that they can capture and process sewage and associated nutrients before they are transported to the Great Lakes. These initiatives will help control flooding and increase the supply of “<a href="https://theconversation.com/a-new-strategy-for-drought-stressed-cities-graywater-recycling-56564">gray water</a>,” or used water from bathroom sinks, washing machines, tubs and showers, for uses such as landscaping.</p>
<p>Cities are coupling this “gray infrastructure” with green infrastructure projects, such as <a href="https://theconversation.com/low-income-neighborhoods-would-gain-the-most-from-green-roofs-in-cities-like-chicago-102234">green roofs</a>, <a href="https://www.chicagobotanic.org/downloads/wed/WI_DNR_homeowners.pdf">infiltration gardens</a> and <a href="https://ijc.org/en/wetland-restoration-projects-urban-great-lakes-help-remediate-areas-concern">reclaimed wetlands</a>. These systems can filter water to help remove excess nutrients. They also will slow runoff during extreme precipitation events, thus recharging natural reservoirs. </p>
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<p>Municipal water managers are also using smart technologies and improved remote sensing methods to create near-real-time warning systems for HABs that might help avert crises. Groups like the <a href="https://clevelandwateralliance.org/">Cleveland Water Alliance</a>, an association of industry, government and academic partners, are working to implement <a href="https://clevelandwateralliance.org/news/2019/02/19/creating-a-smart-lake-erie">smart lake technologies</a> in Lake Erie and other freshwater environments around the globe. Finally, states including <a href="https://www.ocj.com/2020/02/tmdl-announcement-for-lake-erie-led-by-ohio-epa/">Ohio</a> and <a href="https://www.in.gov/core/">Indiana</a> are moving to cut total nutrient inputs into the Great Lakes from all sources, and using advanced modeling to <a href="https://doi.org/10.1029/2019JG005134">pinpoint those sources</a>.</p>
<p>Together these developments could help <a href="https://www.ocj.com/2020/02/tmdl-announcement-for-lake-erie-led-by-ohio-epa/">reduce the size of HABs</a>, and perhaps even reach the roughly 50% reduction in nutrient runoff that government studies suggest is needed to bring them back to their <a href="https://lakeerie.ohio.gov/Portals/0/Reports/Task_Force_Report_October_2013.pdf">minimum extent in the mid-1990s</a>.</p>
<p>Short of curbing global greenhouse gas emissions, keeping communities that rely so heavily on the Great Lakes livable will require all of these actions and more.</p>
<p>[<em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>.]</p><img src="https://counter.theconversation.com/content/131883/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gabriel Filippelli receives funding from the U.S. National Science Foundation and the American Chemical Society-Petroleum Research Fund</span></em></p><p class="fine-print"><em><span>Joseph D. Ortiz receives funding from NASA, the HW Hoover Foundation and the National Geographic Society. He is a participant in the Cleveland Water Alliance, which includes Kent State University. His spouse owns an environmental consulting firm, which is not involved in this project or his research.</span></em></p>Warmer waters, heavier storms and nutrient pollution are a triple threat to Great Lakes cities’ drinking water. The solution: Cutting nutrient releases and installing systems to filter runoff.Gabriel Filippelli, Professor of Earth Sciences and Director of the Center for Urban Health, IUPUIJoseph D. Ortiz, Professor and Assistant Chair of Geology, Kent State University Licensed as Creative Commons – attribution, no derivatives.