tag:theconversation.com,2011:/us/topics/phytoplankton-4210/articlesPhytoplankton – The Conversation2024-02-28T22:31:32Ztag:theconversation.com,2011:article/2245812024-02-28T22:31:32Z2024-02-28T22:31:32ZHow climate change is messing up the ocean’s biological clock, with unknown long-term consequences<figure><img src="https://images.theconversation.com/files/578761/original/file-20240228-30-1ljbi.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3199%2C2400&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A satellite image of a phytoplankton bloom off the coast of St. John's, N.L.</span> <span class="attribution"><span class="source">(NASA, MODIS Rapid Response)</span></span></figcaption></figure><p>Every year in the <a href="https://www.ncesc.com/geographic-faq/what-is-the-middle-and-lower-latitude/">mid-latitudes</a> of the planet, a peculiar phenomenon known as the <a href="https://earthobservatory.nasa.gov/features/Phytoplankton">phytoplankton</a> <a href="https://doi.org/10.1111/gcb.13858">spring bloom</a> occurs. Visible from space, spectacular large and ephemeral filament-like shades of green and blue are <a href="https://doi.org/10.1029/2012GL052756">shaped by the ocean currents</a>.</p>
<p>The phytoplankton blooms are comprised of a myriad of microscopic algae cells growing and accumulating at the ocean’s surface as a result of the onset of longer days and fewer storms — often associated with the move into spring.</p>
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<p>The timing of the phytoplankton spring bloom is, however, <a href="https://doi.org/10.1111/gcb.13886">likely to be altered</a> in response to climate change. Changes which will affect — for good or ill — the many species that are <a href="https://doi.org/10.1146/annurev-marine-052913-021325">ecologically adapted</a> to benefit from the enhanced feeding opportunity that blooms represent at crucial stages of their development.</p>
<h2>Fine-tuned ecological adaptation</h2>
<p>Phytoplankton blooms are, in some aspects, <a href="https://doi.org/10.1111/gcb.14650">metronomes of the annual oceanic cycles</a> around which many species’ biological clocks are synced to.</p>
<p>One example is the zooplankton <a href="https://zooplankton.nl/en/diversity/copepods/"><em>Calanus finmarchicus</em></a>, a class of micro-organism only capable of swimming up and down through the water column. <em>Calanus finmarchicus</em> usually spend the winter in <a href="https://doi.org/10.1146/annurev-marine-010816-060505">diapause</a> — the marine version of hibernation — surviving on their accumulated energy reserves in the deep ocean. At the moment they deem appropriate in the spring, they raise from the abyss to graze on the bloom and reproduce.</p>
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<a href="https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image of a Calanoid Copepod." src="https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578760/original/file-20240228-7861-gu0ol7.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>
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<span class="caption">An image of an individual in the Calanoid Copepod group. The Calanoid Copepod is one of three groups of animals within the general category of Copepods, encompassing around 10,000 species. The Calanus finmarchicus is a member of the Calanoid Copepods group.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>Fish and shellfish, too, are adapted to this natural metronome. </p>
<p>For some species, such as shrimp, females strategically lay their eggs in the water in advance of these blooms so their young will have ample food supplies from the moment they hatch</p>
<p>As incredible as it seems, some species can “calculate” the egg incubation period so that eggs hatch on average <a href="https://doi.org/10.1126/science.1173951">within a week</a> of the expected spring bloom.</p>
<h2>A question of timing</h2>
<p>This, unfortunately, is where climate change is entering into the equation. What was normal in the past may well be changing more rapidly than marine species can adapt. </p>
<p>Zooplankton and fish larvae constitutes the bulk of what ocean scientists call secondary production. Secondary production is a <a href="https://doi.org/10.1139/f2012-050">key trophic level</a> that links primary production (the phytoplankton using the sun’s light to produce biomass) and higher trophic levels, such as fish and marine mammals.</p>
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<a href="https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite image of a phytoplankton bloom." src="https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=607&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=607&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=607&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=762&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=762&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578762/original/file-20240228-30-q7p1qc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=762&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">A massive phytoplankton bloom seen off the Northern coast of Norway. Phytoplankton blooms can reach thousands of square kilometres in size.</span>
<span class="attribution"><span class="source">(ESA, Envisat Pillars)</span></span>
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<p>This grand relationship is known as a <a href="https://doi.org/10.1016/j.tree.2016.08.010">trophic cascade</a>, as the zooplankton are eaten by the small fish and the small fish, in turn, are eaten by the bigger fish. A whole ecosystem beating on a clock largely determined by the timing of the phytoplankton spring bloom, hopefully in sync with the biological clocks of other species.</p>
<p>Any change to the timing of the spring bloom, for example as a result of climate change, can potentially have catastrophic consequences for the survival of zooplankton populations alongside the fishes and ecosystems which rely upon this abundant foodstuff. </p>
<p>This theory is known as the <a href="https://doi.org/10.1016/S0065-2881(08)60202-3">match/mismatch hypothesis</a> and postulates that the consumer’s energy demand should “match” the peak resource availability</p>
<h2>A new understanding</h2>
<p>On the Newfoundland and Labrador shelf in the Northwest Atlantic, the spring bloom <a href="https://doi.org/10.1002/jgrg.20102">generally starts</a> earlier in the south (mid-March on the Grand Banks of Newfoundland) and later in the north (late April on the southern Labrador shelf).</p>
<p>The south-to-north progression of the bloom was long believed to be related to the <a href="https://doi.org/10.1093/plankt/fbm035">annual retreat of sea ice</a> in the region.
But with the duration and spatial extent of the sea ice season being <a href="https://publications.gc.ca/collections/collection_2023/mpo-dfo/Fs97-6-3544-eng.pdf">dramatically reduced</a> in Atlantic Canada over the recent years, the relationship between sea ice and the timing of the bloom weakened.</p>
<p>I — alongside a team of researchers from across Canada — <a href="https://doi.org/10.1002/lol2.10347">proposed a new theory</a> to explain the initiation of the spring bloom on the Newfoundland and Labrador shelf. </p>
<p>Our theory points to transition from winter to spring as being key to trigger the bloom. In winter, cold and stormy conditions keep the ocean well mixed. However, the arrival of spring brings calmer winds and warming temperatures — coupled with increased freshwater flows. These conditions cause the ocean to reorganize into layers of different density — a phenomenon called <a href="https://doi.org/10.1093/plankt/fbv021">re-stratification</a>.</p>
<p>Re-stratification effectively prevents the phytoplankton cells of the upper layers from becoming easily mixed in the maelstrom of oceanic forces.
Their accumulation at the ocean’s surface creates the bloom.</p>
<p>This new mechanism successfully predicts the timing of the phytoplankton spring bloom over more than two decades. It also allows us to better understand the impacts that climate change is having upon our oceans.</p>
<h2>Ecological significance</h2>
<p>Located at the confluence of sub-arctic and sub-tropical ocean currents, the Newfoundland and Labrador shelf is naturally subjected to <a href="https://doi.org/10.5194/essd-13-1807-2021">large fluctuations</a> of its climate, with impacts on the timing of the bloom.</p>
<p>Our study has shown that a warmer climate is associated with earlier re-stratification, earlier phytoplankton blooms and a higher abundance of key zooplankton species such as <em>Calanus finmarchicus</em> in the region.</p>
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Read more:
<a href="https://theconversation.com/climate-change-is-further-reducing-fish-stocks-with-worrisome-implications-for-global-food-supplies-217428">Climate change is further reducing fish stocks with worrisome implications for global food supplies</a>
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<p>This discovery opens the door to a better understanding of bloom dynamics and the oceanic conditions driving the health of the ecosystem.</p>
<p>The good news for a cold region such as the Newfoundland and Labrador shelf is that a warmer climate with milder springs, like the ones we have <a href="https://www.dfo-mpo.gc.ca/csas-sccs/Publications/ResDocs-DocRech/2022/2022_040-eng.html">seen in recent years</a>, will lead to more and more abundant levels of phytoplankton — with clear benefits to ecosystem productivity. </p>
<p>However, for how long these changes will remain positive in a changing climate we cannot say.</p><img src="https://counter.theconversation.com/content/224581/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frédéric Cyr 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>Recent research sheds light on the ocean’s annual ‘biological clock’ and highlights the key dynamics that make it susceptible to climate change.Frédéric Cyr, Adjunct Professor, Physical Oceanography, Memorial University of NewfoundlandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2095722023-08-31T22:28:00Z2023-08-31T22:28:00ZHow analyzing ancient and modern polar bear samples reveals the full scope of global warming<figure><img src="https://images.theconversation.com/files/545815/original/file-20230831-3676-ueot5v.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5061%2C3239&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Analyzing samples of polar bears can reveal not only what they ate but also the food web during their lives. Polar bears pictured live in captivity.</span> <span class="attribution"><span class="source">(AP Photo/Ronald Zak)</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/how-analyzing-ancient-and-modern-polar-bear-samples-reveals-the-full-scope-of-global-warming" width="100%" height="400"></iframe>
<p>The global climate is changing and the <a href="https://www.ipcc.ch/srocc/">Arctic is warming rapidly</a>. These are objectively true statements that most people have come to accept. </p>
<p>But it is also true that <a href="https://climate.nasa.gov/evidence/#:%7E:text=Earth's%20climate%20has%20changed%20throughout%20history.,era%20%E2%80%94%20and%20of%20human%20civilization.">Earth’s climate has never been stagnant</a> and climate anomalies have been frequent throughout the past. </p>
<p>How then, do we understand our current situation relative to past climate shifts? Are the impacts of modern climate change comparable to those of the medieval warm period (MWP) or the little ice age (LIA)? </p>
<p>Our <a href="https://www.sciencedirect.com/science/article/pii/S2213305423000309">recently published study in <em>Anthropocene</em></a> demonstrates a much more substantial impact to polar bears resulting from recent climate change compared to observations over the last 4,000 years. This suggests that current climatic changes are, indeed, unprecedented in human history.</p>
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<a href="https://theconversation.com/arctic-report-card-2022-the-arctic-is-getting-rainier-and-seasons-are-shifting-with-broad-disturbances-for-people-ecosystems-and-wildlife-196254">Arctic Report Card 2022: The Arctic is getting rainier and seasons are shifting, with broad disturbances for people, ecosystems and wildlife</a>
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<h2>Ecosystem background</h2>
<p>Predators at the top of the food chain, like polar bears, <a href="https://link.springer.com/chapter/10.1007/978-1-4612-3498-2_12">reflect changes across the entire ecosystem</a>, all the way down to microscopic algae. </p>
<p>In the Arctic, the base of the food web is sourced from two categories: sea ice-associated algae and open-water phytoplankton, <a href="https://link.springer.com/article/10.1007/s003000050311">which are distinguishable</a> through their carbon isotopes. </p>
<p>In our study area — centred on Lancaster Sound in the Canadian Arctic Archipelago — the food web is fed by a combination of both sea ice algae and phytoplankton. We can assess the relative importance of these two sources through the stable isotopes incorporated into the tissues of animals. </p>
<p>The relative abundance of carbon isotopes does not change as they are transferred through the food web, so these isotopes tell us about <a href="https://www.sciencedirect.com/science/article/abs/pii/0016703778901990">the carbon sources</a> at the base of the food web. <a href="https://esajournals.onlinelibrary.wiley.com/doi/pdfdirect/10.1890/0012-9658(2002)083%5B0703:USITET%5D2.0.CO;2?casa_token=q3M0nAeb-1EAAAAA:p92TARKS7YYyUbX1G0S0YUVN31DqA99kLhmtsC2m178YoxEDkb6olrt_Kcjp5AtTqmvB0i4wKtUa">Nitrogen isotopes do change</a> as they are passed up the food chain, which tells us who is eating whom.</p>
<h2>Results from our study</h2>
<p>In our study we examined stable carbon and nitrogen isotopes in polar bear bone collagen. </p>
<p>The polar bears were all from the Lancaster Sound sub-population and spanned the last 4,000 years. We acquired samples of modern polar bear (1998-2007) obtained through hunting and we were able to compare them to samples from archaeological excavations conducted in the region. </p>
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<figcaption><span class="caption">National Geographic overview of the life-cycle and eating habits of polar bears.</span></figcaption>
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<p>The span of time captured by the archaeological samples was vast, but by dividing them into time bins associated with the <a href="https://www.avataq.qc.ca/en/L-institut/Departements/Archeologie/Decouvrir-l-archeologie/Chronologie-de-l-Arctique">cultural traditions in the region</a> we were able to compare the samples across time before present (BP): pre-Dorset (4000-2800 years BP), Dorset (1500-700 BP) and Thule (700-500 BP). </p>
<p>The Dorset/Thule cultural transition occurred at the onset of the medieval warm period, so a comparison of these time bins allows us to look at the state of the food web before and during a known climate shift. The Thule time bin also extends into the beginning of the little ice age giving us a glimpse into that period as well.</p>
<h2>What it all means</h2>
<p>First, the good news. The results of the nitrogen isotopes showed that throughout time, 4,000 years BP to the present, the structure of the Lancaster Sound food web was relatively unchanged. Polar bears eat seals, seals eat cod, cod eat zooplankton, et cetera. There were no surprising shifts in the diets of polar bears despite past and present climate change. This is comforting.</p>
<p>The results of the carbon isotopes tell a less encouraging story, however. Throughout the four millennia encapsulated by the ancient time bins, we saw stability in the mixture of sea ice algae and open water phytoplankton. We did not detect a difference in the origin of carbon at the base of the food web resulting from the medieval warm period or the little ice age. </p>
<p>The modern samples, however, showed a significant difference in the source of carbon, resulting from a greater proportion of open water phytoplankton and less reliance on sea ice algae.</p>
<h2>Evidence of a warming climate</h2>
<p>Sea ice is an important habitat in the high Arctic. For polar bears it is a platform for hunting. For ringed seals, the <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/06-0546.1?casa_token=v_UExbec6wcAAAAA%3ALGGzkOG-_AsVsjYSgbln1STf38Upm3hjHZQO2mIm1h_Z_f9LerBLBjMw_0D4Eo15WoUO0VgiXDpE">primary prey of polar bears</a>, it is a platform for denning and raising young.</p>
<p>The algae that grows in association with sea ice is also very important for <a href="https://www.sciencedirect.com/science/article/abs/pii/S0079661115001640">jumpstarting biological productivity</a> before the open water season. Our study shows that the loss of biological productivity associated with sea ice is unprecedented on a very long timescale.</p>
<p>Archaeological materials can provide valuable context to the ongoing climate discussion. Much of the valuable work being undertaken is tracking ecosystem changes on a short timescale, seasons to decades. But as we have demonstrated, the Arctic has already changed, so we should not always assume that we are looking at a pristine or undisturbed state. </p>
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Read more:
<a href="https://theconversation.com/human-garbage-is-a-plentiful-but-dangerous-source-of-food-for-polar-bears-finding-it-harder-to-hunt-seals-on-dwindling-sea-ice-183968">Human garbage is a plentiful but dangerous source of food for polar bears finding it harder to hunt seals on dwindling sea ice</a>
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<p>Adding a lens that looks back into the distant past gives resolution and context to our collective understanding of our situation. </p>
<p>In this case, we have illustrated the magnitude of difference occurring in the modern Arctic, relative to past climate anomalies. The medieval warm period and onset of the little ice age were not visible in the isotopes of the Lancaster Sound food web but modern warming is very apparent. We can, therefore, not dismiss calls to action on climate change on the basis that the climate has always fluctuated.</p><img src="https://counter.theconversation.com/content/209572/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This research received funding from an NSERC Discovery grant and the Canada Research Chairs program. </span></em></p>Comparison of modern and archaeological polar bears indicates that four millennia of food web stability has been disrupted by modern climate change.Jennifer Routledge, PhD Candidate, Environmental and Life Sciences, Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2073552023-06-28T15:12:36Z2023-06-28T15:12:36ZFrom raising the global sea level to crushing life on the seafloor – here’s why you should care about icebergs<figure><img src="https://images.theconversation.com/files/534283/original/file-20230627-23-8yvpno.jpg?ixlib=rb-1.1.0&rect=26%2C13%2C4375%2C2923&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Icebergs in Disko Bay, western Greenland.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/icebergs-disco-bay-near-ilulissat-greenland-1888385068">Chris Christophersen/Shutterstock</a></span></figcaption></figure><p>Late in the evening of April 14 1912, the <a href="https://theconversation.com/titanic-twist-1912-wasnt-a-bad-year-for-icebergs-after-all-25621">RMS Titanic collided with an iceberg</a> in the north-west Atlantic. In just over two and a half hours, the Titanic sank, claiming the lives of 1,514 people.</p>
<p>The Titanic disaster is one good reason to understand icebergs better. But their significance extends far beyond posing a risk to ships and other offshore structures. Icebergs are crucial to monitor because of their profound impact on the natural world and human societies.</p>
<p>Icebergs are formed when chunks of ice break off from the front of glaciers and floating ice shelves. They exist in a range of sizes, from small formations known as “growlers” and “bergy bits” (that extend up to 5 metres above sea level), to larger icebergs aptly referred to as “giants”. </p>
<p>In 2000, one of Antarctica’s largest icebergs, <a href="https://earthobservatory.nasa.gov/images/552/iceberg-b-15-ross-ice-shelf-antarctica">called B-15</a>, had a surface area roughly the same size as Jamaica. Since then, <a href="https://earthobservatory.nasa.gov/images/92238/end-of-the-journey-for-iceberg-b-15z">B-15 has fractured</a> into a number of smaller pieces and most have melted away. </p>
<p>Icebergs that break off from an already floating ice shelf do not displace ocean water when they melt, just as melting ice cubes do not raise the liquid level in a glass. But when an ice shelf collapses, it no longer holds back inland glacial ice. This inland ice will then move faster and can rapidly release new icebergs, which displace ocean water and contribute to sea level rise. </p>
<p>In 2022, Antarctica’s <a href="https://theconversation.com/conger-ice-shelf-has-collapsed-what-you-need-to-know-according-to-experts-180077">Conger ice shelf</a> collapsed. Some of the continent’s other large <a href="https://www.antarcticglaciers.org/glaciers-and-climate/changing-antarctica/shrinking-ice-shelves/ice-shelves/">ice shelves</a> are also thought to be at risk of collapse in the future, particularly those around the unstable West Antarctic ice sheet. The collapse of the West Antarctic ice sheet alone could <a href="https://www.antarcticglaciers.org/question/ice-antarctica-melt-much-global-sea-level-rise-quickly-likely-happen/">raise the global sea level by 3.2 metres</a>. </p>
<figure class="align-center ">
<img alt="A glacier calving large chunks of ice into the ocean." src="https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534292/original/file-20230627-15-c2x0zd.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">A chunk of ice breaking off from a glacier in Neko Harbour, Antarctica.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/neko-harbor-glacier-calving-andvord-bay-1556725400">Steve Allen/Shutterstock</a></span>
</figcaption>
</figure>
<p>Global warming accelerates not only iceberg release, but also the rate at which icebergs melt. As icebergs melt, they release freshwater to the ocean. </p>
<p>In the northern hemisphere, a surplus of freshwater from the Greenland ice sheet in the future has the potential to weaken or even shut down the North Atlantic Conveyor “pump”, which circulates warm tropical waters northwards. If the North Atlantic Conveyor pump is significantly affected, the northern hemisphere could be plunged into <a href="https://www.tandfonline.com/doi/abs/10.1080/00167487.2005.12094137">sub-zero, glacial conditions</a>. </p>
<h2>‘Scouring’ the seabed</h2>
<p>Icebergs are often thought of as floating masses of ice. Yet their undersides regularly come into contact with the seabed, gouging out sediment on the seafloor to form “scour” marks. Some <a href="https://www.int-res.com/abstracts/meps/v186/p1-8/">15–20% of the world’s oceans</a> are affected by this phenomenon.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0277379116303638">Research</a> that I co-authored in 2016 on iceberg scouring in East Greenland, found that icebergs can disturb sediment up to several metres below the seabed. This disturbance poses a risk to offshore marine structures such as buried pipelines and telecommunication cables.</p>
<p>Icebergs can also crush plants and animals when they collide with the seabed. These organisms, such as seagrasses and molluscs, are important stores of carbon in polar regions. In areas of West Antarctica, referred to as <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.13523">“iceberg killing fields”</a>, iceberg scouring may recycle around 80,000 tonnes of carbon back into the atmosphere each year. </p>
<h2>Ocean fertilisers (and polluters)</h2>
<p>But it’s not all bad news. Some icebergs contain substantial amounts of iron-rich sediment, known as “dirty ice”. These icebergs <a href="https://www.nature.com/articles/s41467-019-13231-0">fertilise the ocean</a> by supplying important nutrients to marine organisms such as phytoplankton. </p>
<p>Following the passage of an iceberg, there is an increase in organism growth and levels of chlorophyll (the green pigment in plants used for photosynthesis) in the surrounding water. This can result in vibrant blooms that extract CO₂ from the atmosphere as they grow. </p>
<p><a href="https://www.nature.com/articles/ngeo2633">One study</a> on icebergs in the Southern Ocean found that these blooms can be up to ten times the length of the iceberg and can persist for more than a month. Blooms in the wake of icebergs off Antarctica have the capacity to absorb <a href="https://www.cbc.ca/news/science/icebergs-climate-change-1.3401729#:%7E:text=Ocean%20blooms%20in%20the%20wake,as%20Sweden%20or%20New%20Zealand.">up to 40 million tonnes of carbon</a> each year.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A satellite image of a phytoplankton bloom in the Ross Sea, Southern Ocean." src="https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534296/original/file-20230627-29-a5yqmx.jpeg?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">January 22, 2011: a phytoplankton bloom in the Ross Sea, Southern Ocean.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/images/48949/bloom-in-the-ross-sea">Norman Kuring/NASA Goddard Space Flight Center</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>But icebergs hold more than just nutrients in their icy structures. Glacier ice may harbour <a href="https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-021-01106-w">ancient bacterial and viral microbes</a>, even including <a href="https://www.tandfonline.com/doi/full/10.1657/1938-4246-44.4.432">buried faecal microorganisms</a>. These microbes will eventually emerge at the glacier’s surface or in icebergs where they will enter natural ecosystems and could pose a threat to human health. </p>
<p><a href="https://journals.sagepub.com/doi/pdf/10.1177/03091333221107376">Research</a> has also identified various other contaminants within glaciers. These include soot, nuclear fallout, potentially toxic elements such as arsenic, mercury and lead, nitrogen-based contaminants such as fertilisers and animal waste, microplastics and persistent organic pollutants such as pesticides and solvents. </p>
<p>Scientists are, however, exploring the possibility of <a href="https://www.nature.com/articles/s41598-022-26952-y#:%7E:text=A%20long%2Dheld%20idea%20is,United%20Arab%20Emirates%20(UAE)">towing icebergs to water-scarce regions</a>. An iceberg holding 20 billion gallons of freshwater could potentially <a href="https://www.theguardian.com/environment/2017/may/05/could-towing-icebergs-to-hot-places-solve-the-worlds-water-shortage">meet the water needs of a million people</a> for five years – provided that the water is uncontaminated. </p>
<p>Icebergs have an impact on our oceans, atmosphere and societies. As the climate emergency intensifies and our glaciers and ice sheets continue to recede, the significance of icebergs will only grow, for better or worse.</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">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>Lorna Linch 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>Icebergs don’t just pose a risk to ships – they have a profound impact on the natural world and human societies.Lorna Linch, Principal Lecturer in Physical Geography, University of BrightonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2072192023-06-15T06:56:55Z2023-06-15T06:56:55ZOceans absorb 30% of our emissions, driven by a huge carbon pump. Tiny marine animals are key to working out its climate impacts<figure><img src="https://images.theconversation.com/files/531908/original/file-20230614-28-ritl1a.png?ixlib=rb-1.1.0&rect=12%2C1%2C894%2C598&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Julian Uribe-Palomino/IMOS-CSIRO</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The ocean holds 60 times more carbon than the atmosphere and absorbs almost 30% of carbon dioxide (CO₂) emissions from human activities. This means the ocean is key to understanding the global carbon cycle and thus our future climate. </p>
<p>The Intergovernmental Panel on Climate Change (IPCC) uses earth system models to project climate change. These projections inform critical political, social and technological decisions. However, if we can’t accurately model the marine carbon cycle then we cannot truly understand how Earth’s climate will respond to different emission scenarios. </p>
<p>In <a href="https://www.nature.com/articles/s43247-023-00871-w">research published today</a>, we show that zooplankton, tiny animals near the base of the ocean food chain, are likely to be the biggest source of uncertainty in how we model the marine carbon cycle. Getting their impact on the cycle right could add an extra 2 billion tonnes to current models’ assumptions about annual carbon uptake by the ocean. That’s more carbon than the entire global transportation sector emits.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph showing global carbon budget with emissions and sinks" src="https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=590&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=590&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=590&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=741&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=741&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532100/original/file-20230615-22-8v22hr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=741&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 ocean (dark green) is a major carbon sink that partly offsets emissions in the global carbon budget.</span>
<span class="attribution"><a class="source" href="https://essd.copernicus.org/articles/14/4811/2022/">Global Carbon Budget 2022, Friedlingstein et al</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/oceans-are-better-at-storing-carbon-than-trees-in-a-warmer-future-ocean-carbon-sinks-could-help-stabilise-our-planet-176154">Oceans are better at storing carbon than trees. In a warmer future, ocean carbon sinks could help stabilise our planet</a>
</strong>
</em>
</p>
<hr>
<h2>Marine carbon cycling is a $3 trillion thermostat</h2>
<p>Roughly <a href="https://essd.copernicus.org/articles/14/4811/2022/">10 billion tonnes</a> of carbon are being released into the atmosphere each year. But the ocean quickly absorbs about 3 billion tonnes of these emissions, leaving our climate cooler and more hospitable. If we <a href="https://www.ipcc.ch/sr15/chapter/chapter-2/">price carbon</a> at the rate the IPCC believes is needed to limit warming to 1.5°C, this adds up to over A$3 trillion worth of emission reductions accomplished naturally by the ocean every year. </p>
<p>However, we know the size of the ocean carbon sink has changed in the past, and even small changes can lead to big changes in the atmosphere’s temperature. Thus, we understand the ocean acts as a thermostat for our climate. But what controls the dial? </p>
<p>Extensive <a href="https://www.nature.com/articles/35038000">geological evidence</a> suggests microscopic marine life could be in control. Phytoplankton photosynthesise and consume <a href="https://www.nature.com/articles/483S17a#:%7E:text=Although%20they%20account%20for%20less,world's%20land%20plants%20combined2.">as much CO₂ as all land plants</a>. </p>
<p>When phytoplankton die, they sink and trap much of their carbon deep in the ocean. It can remain there for centuries to millennia, locked away safely out of contact with the atmosphere. </p>
<p>Any changes to the strength of this biological carbon pump will be felt in the atmosphere and <a href="https://scitechdaily.com/little-known-microbes-could-be-an-early-warning-signal-of-climate-tipping-point/">will change our climate</a>. Some have even proposed enhancing this biological pump by artificially fertilising the ocean with iron to stimulate phytoplankton. It’s possible this could sequester as much as an extra 20% of our annual CO₂ emissions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The marine biological carbon pump" src="https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=689&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=689&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=689&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=866&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=866&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531909/original/file-20230614-17-p7rifi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=866&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 diagram of the natural biological carbon pump and how iron fertilisation could artificially enhance it.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s43247-023-00871-w">Rohr et al (2019)</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/smoke-from-the-black-summer-fires-created-an-algal-bloom-bigger-than-australia-in-the-southern-ocean-164564">Smoke from the Black Summer fires created an algal bloom bigger than Australia in the Southern Ocean</a>
</strong>
</em>
</p>
<hr>
<h2>Right for the wrong reasons</h2>
<p>Despite its <a href="https://scitechdaily.com/little-known-microbes-could-be-an-early-warning-signal-of-climate-tipping-point/">importance for the global climate</a> and food production, there are large gaps in our understanding of how the marine carbon cycle is expected to change. Most earth system models differ in how the cycle’s major components will respond to a changing climate. Models simply can’t agree on what will happen to:</p>
<ul>
<li><p>net primary production – the carbon consumed by phytoplankton resulting in growth of marine plants at the base of the food web</p></li>
<li><p>secondary production – zooplankton growth, which is an indicator for fisheries, since fish eat zooplankton</p></li>
<li><p>export production – the biological pump of carbon transferred to the deep sea. </p></li>
</ul>
<p>To diagnose what might be going wrong, we compared the marine carbon cycle in 11 IPCC earth system models. We found the largest source of uncertainty is how fast zooplankton consume their phytoplankton prey, known as grazing pressure. </p>
<p>Models differ hugely in their assumptions about this grazing pressure. Even if zooplankton were exposed to the exact same amount of phytoplankton, the highest assumed grazing rate would be almost 100 times as fast as the slowest rate.</p>
<p>This is because some models effectively assume the ocean is filled entirely with slow-grazing shrimp. Others assume it is teeming exclusively with microscopic, but rapidly grazing <a href="https://www.britannica.com/science/ciliate">ciliates</a>. In reality, neither is true. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=507&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=507&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=507&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=638&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=638&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531912/original/file-20230614-24-99hkpp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=638&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Differences in prominent models’ estimates of the amount of zooplankton at different latitudes.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s43247-023-00871-w">Adapted from Rohr et al (2023)</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tiny-plankton-drive-processes-in-the-ocean-that-capture-twice-as-much-carbon-as-scientists-thought-136599">Tiny plankton drive processes in the ocean that capture twice as much carbon as scientists thought</a>
</strong>
</em>
</p>
<hr>
<p>Models must make up for such large differences in zooplankton grazing by making additional assumptions about how fast phytoplankton grow and how quickly zooplankton die. Together, these differences can be balanced in a way that allows most models to simulate the present-day amount of carbon consumed by phytoplankton and transferred to the deep sea. </p>
<p>However, that is only because we can observe what those values should be. We can then tune models until we ensure they get the right answer. </p>
<p>Yet, even though our best models can admirably recreate the present-day ocean, they do so for different reasons and with dramatically different assumptions about the role of zooplankton. This means these models are built with fundamentally different machinery. When used to test future emissions scenarios, they will project fundamentally different outcomes. </p>
<p>We cannot know which projections are correct unless we know the true role of zooplankton. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1664916490406043649"}"></div></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-modelling-micro-algae-to-better-understand-the-workings-of-the-ocean-204412">Climate: modelling micro-algae to better understand the workings of the ocean</a>
</strong>
</em>
</p>
<hr>
<h2>Tiny plankton with a big impact</h2>
<p>We ran a sensitivity experiment to show how small changes in zooplankton grazing can dramatically alter marine carbon cycling. We considered two sets of experiments, one control and one in which we increased both zooplankton grazing rates and phytoplankton growth rates, such that both were tuned to the exact same total carbon consumption by phytoplankton. </p>
<p>This increase in how fast zooplankton can graze was only a fraction of the difference between assumed grazing rates seen across IPCC models. Despite this, we found even this small increase led to a huge difference in the percentage of carbon consumed by phytoplankton that was eventually exported to depth and transferred up the food chain. </p>
<p>Ocean carbon storage increased by 2 billion tonnes per year. Zooplankton carbon consumption increased by 5 billion tonnes. </p>
<p>From a climate perspective, that is double the maximum theoretical potential of iron fertilisation. From a fisheries perspective, that leads to a 50% increase in the size of the global zooplankton population on which many fish feed. This matters for global food supply as the ocean feeds 10% of the global population.</p>
<p>This work shows we must improve both our understanding and modelling of zooplankton. With limited resources and an immense ocean, we will never have enough observations to build perfect models. However, new technologies for measuring zooplankton are making it easier to make autonomous, high-resolution measurements of many important variables. </p>
<p>We must make a concerted effort to leverage these new technologies to better understand the role of zooplankton in the marine carbon cycle. We will then be able to reduce uncertainties about future climate states, advance our ability to assess marine-based CO₂ removal, and improve global fisheries projections.</p><img src="https://counter.theconversation.com/content/207219/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anthony Richardson receives funding from the Australian Research Council Discovery Project DP230102359 and Australia’s Integrated Marine Observing System (IMOS) enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). </span></em></p><p class="fine-print"><em><span>Elizabeth Shadwick receives funding from Australian Government's Antarctic Science Collaboration Initiative, and Australia’s Integrated Marine Observing System (IMOS) enabled by the National Collaborative Research Infrastructure Strategy (NCRIS).</span></em></p><p class="fine-print"><em><span>Tyler Rohr 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>Marine life known as zooplankton might be the biggest problem with getting carbon cycling right in climate models. The potential variations in carbon uptake are greater than global transport emissions.Tyler Rohr, Lecturer in Southern Ocean Biogeochemical Modelling, IMAS, University of TasmaniaAnthony Richardson, Professor, The University of QueenslandElizabeth Shadwick, Team Leader, Oceans & Atmosphere, CSIROLicensed 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/1911522022-09-27T13:11:58Z2022-09-27T13:11:58ZNigeria’s sacred Osun River supports millions of people - but pollution is making it unsafe<figure><img src="https://images.theconversation.com/files/486262/original/file-20220923-9077-t1qt1j.jpg?ixlib=rb-1.1.0&rect=16%2C5%2C3578%2C2382&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Osun River has become turbid and unsafe for consumption - threatening its cultural and biodiversity significance. Photo by: Stefan Heunis/AFP via Getty Images.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/woman-throws-a-sacrificial-chicken-into-the-sacred-river-news-photo/1018606984?adppopup=true">from www,gettyimages.com</a></span></figcaption></figure><p><em>Pollution has become a worrying threat to Nigeria’s Osun River. The river supports millions of people who rely on the water for agriculture as well as industries. It is also an integral part of Nigeria’s treasured Osun-Osogbo sacred grove, a UNESCO world heritage site. Emmanuel O. Akindele unpacks what’s causing the pollution, what harm it’s causing and what must change to preserve the river’s biodiversity.</em> </p>
<h2>How important is the Osun River to Nigeria?</h2>
<p>The Osun River is one of the major rivers in southern Nigeria, <a href="https://link.springer.com/article/10.1007/s11356-020-08763-8">draining into the Gulf of Guinea</a>. The river takes its source from Ekiti State. But it’s culturally linked to the ancient city of <a href="https://core.ac.uk/download/pdf/236410037.pdf">Osogbo</a>. A stretch of the river that flows by a sacred grove in the ancient town of Osogbo has been designated a <a href="https://whc.unesco.org/en/list/1118/">UNESCO World Heritage Site</a> due to its <a href="https://whc.unesco.org/en/list/1118">cultural</a> significance. It is one of two such designated sites in <a href="https://whc.unesco.org/en/statesparties/ng">Nigeria</a>. </p>
<p>The river provides a wide range of cultural ecosystem services such as <a href="https://afribary.com/works/assessment-of-the-ecotourism-potentials-of-osun-osogbo-world-heritage-site-osun-state-nigeria">natural scenes</a> for eco-tourists and the site for filming Nollywood movies. A large number of foreign tourists <a href="https://www.academia.edu/52361771/HARNESSING_CULTURAL_HERITAGE_FOR_TOURISM_DEVELOPMENT_IN_NIGERIA_A_STUDY_OF_THE_OSUN_OSOGBO_SACRED_GROVE_AND_FESTIVAL">visit</a> the river each year. The visits are either to pay homage to the river goddess (Osun) or to join others in celebrating the <a href="https://www.vanguardngr.com/2022/08/2022-osun-festival-begins-with-spiritual-cleansing-of-roads/">annual Osun festival</a>. </p>
<p>The river also has enormous environmental value given its rich <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/aje.12482">biodiversity</a>. It supports <a href="https://www.tandfonline.com/doi/abs/10.1080/21658005.2017.1357290?journalCode=tzec20">plankton</a>, <a href="https://www.scielo.sa.cr/scielo.php?script=sci_arttext&pid=S0034-77442007000200034">snakes</a> and <a href="https://www.frim.gov.my/v1/JTFSOnline/jtfs/v26n1/5-15.pdf">endangered plants</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A flowing river bordered by dense forest." src="https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/486269/original/file-20220923-2090-r25747.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">Osun River is one of the last remnants of primary high forest in southern Nigeria - UNESCO World Heritage Site. But pollution is threatening the river.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/osun-river-osun-osogbo-sacred-grove-osogbo-osun-royalty-free-image/1141985549?adppopup=true">from www.gettyimages.com</a></span>
</figcaption>
</figure>
<p>Along its whole course, the Osun River also plays a <a href="https://www.tandfonline.com/doi/pdf/10.1080/16583655.2019.1567899">critical part</a> in supporting the livelihoods of people. In many areas of Osogbo and Osun State, it provides irrigation for nearby farmlands. A significant number of abattoirs are also situated close to the river bank along several stretches of its course. </p>
<p>The Osun River flows through other human settlements in southwest Nigeria as well as the historic city of Osogbo.</p>
<h2>What are the main sources of the pollution?</h2>
<p>Plastic pollution is the main one. My research has shown that some <a href="https://theconversation.com/nigerian-river-snails-carry-more-microplastics-than-rhine-snails-126622">aquatic snails</a> and <a href="https://theconversation.com/why-microplastics-found-in-nigerias-freshwaters-raise-a-red-flag-147432">insects</a> of the river carry microplastic pollutants. Plastic pollution is a common phenomenon in many inland waters of Nigeria. </p>
<p>Heavy metals also pollute the river. Heavy metals like gold, mercury and cadmium <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4144270/">occur naturally</a> in the Earth’s crust. But they can also be introduced through domestic and industrial wastes, or atmospheric sources. Heavy metals can be <a href="https://www.sciencedirect.com/science/article/pii/S2405844020315346">amplified</a> by human activities like waste deposition or mining. Mining loosens heavy metals buried in the earth, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129257/">adding more of them</a> to water. </p>
<p>Artisanal gold mining within the catchments of the Osun River, especially around the Ijesha land area of Osun State, have further worsened the ecological condition of the river and made the water <a href="https://www.premiumtimesng.com/news/top-news/548204-osun-osogbo-festival-govt-warns-devotees-tourists-against-drinking-from-river.html">unsafe</a> for human use. </p>
<p>The impact of illegal gold mining on the river cannot be over-emphasised. First, the impacts have been felt on the river’s water quality, which has deteriorated. This has grave implications for its <a href="http://medcraveonline.com/BIJ/water-pollution-and-aquatic-biodiversity.html">biological diversity</a>.</p>
<p>Aside from the introduction of toxicants, the river, which was once <a href="https://www.tandfonline.com/doi/abs/10.1080/21658005.2017.1357290?journalCode=tzec20">transparent</a> enough for photosynthetic production, is now very turbid (cloudy) with a characteristic gold colour. At extremely low water transparency, a river’s phytoplankton primary production could be <a href="https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1046&context=oak-lake_research-pubs">threatened</a>, and by implication, its secondary (fish) production could also be threatened. It can also cause fish to die by <a href="https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/255660.pdf">blocking</a> their gills and destroying their reproductive sites. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/KMmMsKIVuTk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Osun river pollution. Credit: UrbanAlert,</span></figcaption>
</figure>
<p>Another source of pollution is human-generated <a href="https://www.voanews.com/a/nigeria-s-osun-river-sacred-revered-and-increasingly-toxic/6708178.html">waste</a> that lands up in the river. This is due to <a href="https://theconversation.com/nigerias-plastic-pollution-is-harming-the-environment-steps-to-combat-it-are-overdue-177839">poor waste management practice</a> – a feature common in many urban areas in Nigeria. </p>
<h2>What are the solutions?</h2>
<p>The government must first halt all mining near the river until environmental audits have been conducted, placing urgent human welfare ahead of short-term economic gains. Although the river has already suffered significant harm, it is still possible to halt mining operations so that toxicant concentrations do not keep rising and the river can recuperate from the stress of pollution. </p>
<p>Through natural processes, rivers and streams have the ability to <a href="https://www.sciencedirect.com/science/article/pii/S187802961101022X?via%3Dihub">purify</a> themselves. However, in the instance of the Osun River, this can only happen after the various sources of pollution are stopped. </p>
<p>If further gold mining operations are suggested following an environmental audit of the Osun River, it will be crucial to reroute effluents from all natural waters in the basin. A special reservoir can be constructed in a location far away from where people live and make their living.</p>
<p>A polluted and unsafe environment for plants and animals is a reliable indicator of a similarly unsafe environment for people.</p><img src="https://counter.theconversation.com/content/191152/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emmanuel O. Akindele receives funding from the British Ecological Society. </span></em></p>The ability of the Osun River to support biodiversity is being threatened by pollution and can only be rescued if the contamination ends.Emmanuel O. Akindele, Senior Lecturer, Obafemi Awolowo UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1888462022-08-24T14:53:55Z2022-08-24T14:53:55ZJellyfish alert: increased sightings signal dramatic changes in ocean food web due to climate change<figure><img src="https://images.theconversation.com/files/480835/original/file-20220824-14-7td2j9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4928%2C3260&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/lionsmane-jellyfish-seas-inner-hebrides-on-386531131">Joost van Uffelen/Shutterstock</a></span></figcaption></figure><p>Did you see a jellyfish on a recent trip to the seaside? UK beachgoers are <a href="https://theconversation.com/why-holidaymakers-are-seeing-giant-jellyfish-off-the-uk-coast-and-what-to-do-if-you-are-stung-165652">more likely to spot one</a> now than in the past, as rising sea temperatures due to climate change have ushered more of these gelatinous animals into the waters around northern Europe.</p>
<p>Jellyfish don’t swim like fish. They belong to the plankton: a diverse group of marine creatures that drift through the sea, floating wherever the currents take them. Jellyfish are among the few types of plankton visible to the human eye. Most plankton are tiny (smaller than 2mm) and can only be seen with a microscope.</p>
<p>Although largely invisible, plankton are the base of the ocean food web, eaten by fish, seabirds and even whales. Species that don’t eat plankton, like seals, will eat organisms that do. Globally, phytoplankton (single-celled algae which, like trees and shrubs on land, are mostly green in colour and use chlorophyll to photosynthesise) <a href="https://theconversation.com/inside-the-world-of-tiny-phytoplankton-microscopic-algae-that-provide-most-of-our-oxygen-159955">produce half of the oxygen</a> we breathe.</p>
<p>Increasingly abundant jellyfish are just one example of the many ways that plankton are reflecting climate change’s influence on the ocean. My research team has found that the species making up North Atlantic plankton communities are also <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.15066">shifting as sea temperatures rise</a>.</p>
<p>We analysed <a href="https://essd.copernicus.org/articles/13/5617/2021/">plankton data</a> collected using nets and bottles throughout the northeast Atlantic over the past 80 years. <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.15066">We found</a> that the larvae of crabs, starfish, sea urchins and lobsters are becoming more common, while shrimp-like crustaceans called copepods (a critical food source for fish, seabirds and even basking sharks) are declining.</p>
<figure class="align-center ">
<img alt="Translucent, microscopic creatures on a black background." src="https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480841/original/file-20220824-4729-sdo0s6.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">Copepods are a rich food source for a variety of fish.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/plankton-organisms-drifting-oceans-seas-zooplankton-1356428912">Choksawatdikorn/Shutterstock</a></span>
</figcaption>
</figure>
<p>These are big changes among some of the smallest forms of life, and they will affect the entire marine food web, as well as humans. We must understand these changes in order to adapt to them. That could mean new fishing practices – and even diets.</p>
<h2>In a jellyfish’s wake</h2>
<p>Zooplankton (the animal subset of plankton) consists not only of copepods and jellyfish, but also the larval stages of fish, crustaceans and echinoderms (the “spiny skin” group that starfish and sea urchins belong to) which later settle to the sea floor and mature into their familiar adult forms. Both zooplankton and phytoplankton communities are highly diverse, containing species of all sorts of weird and wonderful shapes.</p>
<p>Since the 1960s, colder-water zooplankton species have been <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2009.01848.x">retreating</a> towards the Arctic, followed by warmer-water species that are also tracking rising sea temperatures northwards. The warmer-water zooplankton species which now dominate northern European waters are generally smaller and less nutritious than the cold-water species they have replaced.</p>
<p>The seasonal timing of when plankton are abundant in the North Sea has also <a href="https://www.nature.com/articles/nature02808">shifted</a>, including around the UK. While the seasonal cycle of phytoplankton is driven by sunlight and so hasn’t changed, the point in the year when some zooplankton species are most abundant now arrives earlier, as shorter and warmer winters cause the eggs of some species to hatch sooner. This has meant a mismatch between the spring phytoplankton bloom and the annual peak abundance of the zooplankton that gorge on it.</p>
<figure class="align-center ">
<img alt="A satellite image of the ocean with a turquoise plume." src="https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480839/original/file-20220824-14-c7wdy8.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">Phytoplankton blooms are usually so vast they can be seen from space.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aerial-turquoise-ocean-photo-clear-sky-2102266519">GizemG/Shutterstock</a></span>
</figcaption>
</figure>
<p>These shifts have meant the quantity and type of food available to larval fish (which are zooplankton themselves but eat smaller zooplankton) is changing in the North Atlantic. Warm-water species such as bluefin tuna and anchovies are now <a href="https://www.mccip.org.uk/fisheries">commonly found</a> in northern European waters, while cod, herring, whiting and sprat, all important commercial fish species, have declined in number.</p>
<p>Fishery managers need to work with scientists to set quotas that ensure these new species are fished sustainably, while coastal fishing communities may have to catch new species as familiar ones decline. The public may have to adapt their diets too as traditional species, such as cod in the UK, become scarcer.</p>
<p>The jellyfish you now see in UK waters might have once been a rarity, but it’s following a (largely invisible) crowd that is upending marine food webs and changing the kind of fish you might buy and eat locally. The next time you watch the hypnotic motion of one of these beautiful creatures as it pulses through the water, think of the changes its arrival portends, both for the ocean and yourself.</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">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>Abigail McQuatters-Gollop receives funding from NERC, EMFF and Defra. </span></em></p>Plankton, some of the smallest organisms on Earth, are leading big changes in the ocean.Abigail McQuatters-Gollop, Associate Professor of Marine Conservation, University of PlymouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1645642021-09-15T20:05:48Z2021-09-15T20:05:48ZSmoke from the Black Summer fires created an algal bloom bigger than Australia in the Southern Ocean<figure><img src="https://images.theconversation.com/files/421239/original/file-20210915-15-1g32pkx.jpg?ixlib=rb-1.1.0&rect=0%2C34%2C2851%2C1864&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Himawari-8</span>, <span class="license">Author provided</span></span></figcaption></figure><p>In 2019 and 2020, bushfires razed more than <a href="https://www.unep.org/news-and-stories/story/ten-impacts-australian-bushfires">18 million hectares</a> of land in Australia. For weeks, smoke choked major cities, leading to <a href="https://www.abc.net.au/news/2020-05-26/bushfire-royal-commission-hearings-smoke-killed-445-people/12286094">almost 450 deaths</a>, and even <a href="https://atmosphere.copernicus.eu/sites/default/files/2020-01/Logo_ifs_omaod_animation_fc_spacific_20200107.mp4">circumnavigated</a> the southern hemisphere. </p>
<p>As the aerosols billowed across the oceans many thousands of kilometres away from the fires, microscopic marine algae called phytoplankton had an unexpected windfall: they received a boost of iron.</p>
<p><a href="https://www.nature.com/articles/s41586-021-03805-8">Our research</a>, published today in Nature, found this caused phytoplankton concentrations to double between New Zealand and South America, until the bloom area became bigger than Australia. And it lasted for four months. </p>
<p>This enormous, unprecedented algal bloom could have profound implications for carbon dioxide levels in the atmosphere and for the marine ecosystem. But so far, the impact is still unclear.</p>
<p>Meanwhile, <a href="https://www.nature.com/articles/s41586-021-03712-y">in another paper</a> published alongside ours in Nature today, researchers from The Netherlands found the amount of carbon dioxide emitted by the fires that summer was more than double previous estimates. </p>
<h2>Absorbing 680 million tonnes of carbon dioxide</h2>
<p>Iron fertilises phytoplankton and helps them grow, in the same way nutrients added in soil help vegetables grow. And like plants on land, phytoplankton photosynthesise — they <a href="https://theconversation.com/humans-will-always-have-oxygen-to-breathe-but-we-cant-say-the-same-for-ocean-life-165148">absorb CO₂</a> as they grow and produce oxygen for fish and other marine creatures.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421240/original/file-20210915-23-19dwd57.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">Bushfire smoke is an aerosol made up of many different chemicals, including iron.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>We used satellite data to estimate that for phytoplankton to grow as much as they did in the Southern Ocean, they would have absorbed 680 million tonnes of CO₂. This means the phytoplankton absorbed roughly the same amount of CO₂ as released by the bushfires, according to the latest estimates <a href="https://www.nature.com/articles/s41586-021-03712-y">released today</a>. </p>
<p>The Dutch researchers found the bushfires released 715 million tonnes of CO₂ (or ranging 517–867 million tonnes) between November 2019 and January 2020. This surpasses Australia’s normal annual fire and fossil fuel emissions by 80%.</p>
<p>To put this into perspective, Australia’s anthropogenic CO₂ emissions <a href="https://www.industry.gov.au/sites/default/files/April%202021/document/national-inventory-report-2019-volume-1.pdf">in 2019</a> were much less, at 520 million tonnes.</p>
<h2>Phytoplankton can have dramatic effects on climate</h2>
<p>But that doesn’t mean the phytoplankton growth absorbed the bushfire’s CO₂ emissions permanently. Whether phytoplankton growth extracts and keeps CO₂ from the atmosphere depends on their fate. </p>
<p>If they sink to the deep ocean, then this represents <a href="https://www.whoi.edu/press-room/news-release/the-oceans-biological-pump-captures-more-carbon-than-expected/">a carbon sink</a> for decades or even centuries — or even longer if phytoplankton are stored in ocean sediments. </p>
<p>But if they’re mostly eaten and decomposed near the ocean’s surface, then all that CO₂ they consumed comes straight back out, with no net effect on the carbon balance in the atmosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421238/original/file-20210915-17-1kwycw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=415&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Himawari satellite image showing the January aerosol plume stretching over the South Pacific.</span>
<span class="attribution"><span class="source">Himawari-8</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In fact, phytoplankton have very likely <a href="http://www.homepages.ed.ac.uk/shs/Climatechange/Carbon%20sequestration/Martin%20iron.htm">played a role</a> on millennial time scales in keeping atmospheric CO₂ concentrations down, and can affect the global climate in the long term.</p>
<p>For example, <a href="https://science.sciencemag.org/content/343/6177/1347">a 2014 study suggests</a> iron-containing dust billowing over the Southern Ocean caused increased phytoplankton productivity, which contributed to reducing atmospheric CO₂ by about 100 parts per million. And this helped transition the planet to ice ages. </p>
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Read more:
<a href="https://theconversation.com/inside-the-world-of-tiny-phytoplankton-microscopic-algae-that-provide-most-of-our-oxygen-159955">Inside the world of tiny phytoplankton – microscopic algae that provide most of our oxygen</a>
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</p>
<hr>
<p>Phytoplankton blooms can also have a big impact on the marine ecosystem as they make excellent food for some marine creatures. </p>
<p>For example, more phytoplankton means more food for zooplankton that feed on phytoplankton, with effects up the food chain. It’s also worth noting this huge bloom occurred at a time of year when phytoplankton are usually in decline in this part of the ocean.</p>
<p>But whether there were any long-lasting effects from the bushfire-fuelled phytoplankton on the climate or ecosystem is unclear, because we still don’t know where they ended up.</p>
<h2>Using revolutionary data</h2>
<p>The link between fire aerosols and the increase in phytoplankton demonstrated in our study is particularly relevant given the <a href="https://neo.sci.gsfc.nasa.gov/view.php?datasetId=MOD14A1_M_FIRE">intense fire activity</a> around the globe. </p>
<p>Droughts and warming under global climate change are expected to increase the frequency and intensity of wildfires, and the impacts to land-based ecosystems, such as habitat loss and air pollution, will be dramatic. But as we now know, wildfires can also affect marine life thousands of kilometres away from land.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421241/original/file-20210915-25-5g8umv.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">A robotic float being deployed on board the CSIRO RV Investigator.</span>
<span class="attribution"><span class="source">Jakob Weiss</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Previous <a href="https://doi.org/10.5194/bg-8-1679-2011">models</a> have predicted the iron-fertilising effect of bushfire aerosols, but this is the first time we’ve observed and demonstrated the connection at a large-scale. </p>
<p>Our study is mainly based on satellite data and observations from robotic floats that roam the oceans and collect data autonomously. These <a href="https://biogeochemical-argo.org">robotic floats</a> are revolutionising our understanding of chemical cycling, oxygen variability and ocean acidification.</p>
<p>During the bushfire period, our smoke tracers reached concentrations at least 300% higher than what had ever been observed in the 22-year satellite record for the region.</p>
<p>Interestingly, you wouldn’t be able to observe the resulting phytoplankton growth in a true-colour satellite image. We instead used more sensitive ocean colour sensors on satellites to estimate phytoplankton concentrations.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tiny-plankton-drive-processes-in-the-ocean-that-capture-twice-as-much-carbon-as-scientists-thought-136599">Tiny plankton drive processes in the ocean that capture twice as much carbon as scientists thought</a>
</strong>
</em>
</p>
<hr>
<h2>So what’s next?</h2>
<p>Of course, we need more research to determine the fate of the phytoplankton. But we also need more research to better predict when and where aerosol deposition (such as bushfire smoke) will boost phytoplankton growth. </p>
<p>For example, the Tasman Sea — between Australia and New Zealand — showed only mildly higher phytoplankton concentrations during the bushfire period, even though the smoke cloud was strongest there. </p>
<p>Was this because nutrients other than iron were lacking, or because there was less deposition? Or perhaps because the smoke didn’t stick around for <a href="https://doi.org/10.1021/acs.est.6b02605">as long</a>?</p>
<p>Whatever the reason, it’s clear this is only the beginning of exciting new lines of research that link forests, wildfires, phytoplankton growth and Earth’s climate.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/some-animals-have-excellent-tricks-to-evade-bushfire-but-flames-might-be-reaching-more-animals-naive-to-the-dangers-164894">Some animals have excellent tricks to evade bushfire. But flames might be reaching more animals naive to the dangers</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/164564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christina Schallenberg receives funding from the Integrated Marine Observing System (IMOS) and is affiliated with the Australian Antarctic Program Partnership (AAPP). In the past, she received funding from the National Sciences Engineering and Research Council (NSERC) of Canada. </span></em></p><p class="fine-print"><em><span>Jakob Weis receives funding from the Australian Research Council Centre of Excellence for Climate Extremes.</span></em></p><p class="fine-print"><em><span>Joan Llort receives funding from the European Union’s Horizon 2020 - MSCA program.</span></em></p><p class="fine-print"><em><span>Peter Strutton receives funding from the Australian Research Council and Australia's Integrated Marine Observing System (IMOS), which is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). </span></em></p><p class="fine-print"><em><span>Weiyi Tang receives funding from Princeton University and previously received funding from National Science Foundation. </span></em></p>This enormous, unprecedented algal bloom could have profound implications for carbon dioxide levels in the atmosphere and for the marine ecosystem.Christina Schallenberg, Research Fellow, University of TasmaniaJakob Weis, Ph.D. student, University of TasmaniaJoan Llort, Oceanógrafo , Barcelona Supercomputing Center-Centro Nacional de Supercomputación (BSC-CNS)Peter Strutton, Professor, Institute for Marine and Antarctic Studies, University of TasmaniaWeiyi Tang, Postdoc in Biogeochemistry, Princeton UniversityLicensed 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/1599552021-04-29T15:21:35Z2021-04-29T15:21:35ZInside the world of tiny phytoplankton – microscopic algae that provide most of our oxygen<figure><img src="https://images.theconversation.com/files/397791/original/file-20210429-19-8lbh7j.jpg?ixlib=rb-1.1.0&rect=115%2C115%2C5396%2C3999&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/volvox-polyphyletic-genus-chlorophyte-green-algae-558059725">Shutterstock/Choksawatdikorn</a></span></figcaption></figure><p>Phytoplankton are microscopic algae living throughout the ocean’s surface waters. They can’t swim and are at the mercy of the currents and tides. Despite their small size, phytoplankton enable life in the oceans – and throughout the planet – to exist.</p>
<p>There are two types of plankton – zooplankton, which are animals, and phytoplankton, which are algae. Phytoplankton are filled with chlorophyll which gives them a green colour, just like land plants. And like land plants, phytoplankton play a critical role, converting carbon dioxide and energy from the sun into food through photosynthesis, producing oxygen. </p>
<p>These tiny organisms have been producing oxygen for the world for hundreds of millions of years. But most people know very little about them, what they do for the rest of the world and the threats they are facing.</p>
<p>Phytoplankton are thought to have made an appearance in the Bible’s Book of Revelation, which says: “A third of the sea turned into blood, a third of the living creatures in the sea died, and a third of the ships were destroyed”. Modern scientists think this must be a reference to a harmful algal bloom, or red tide, that can be cause by phytoplankton and can discolour that water. These can also produce toxins, causing illness and even death in animals – <a href="https://www.sciencedirect.com/science/article/pii/S1568988321000160">fish</a>, <a href="https://peerj.com/articles/3123/">whales</a>, <a href="https://www.sciencedirect.com/science/article/pii/S1568988308001571?casa_token=px7Q1iYbEI0AAAAA:qdcWssl9s6eowloHuz4OgBaTKyLo8wf_gcSFPuXCm5tShlz5QaBjxcAF3ELWfIv90QmcbfWdAw">manatees</a>, <a href="https://www.sciencedirect.com/science/article/pii/S1568988312001175?casa_token=XT7ZylxInu0AAAAA:b0SLek_vefPziV7dRiuawt1dlOe6U6tABXyS8toMTYkdFfZzzRbKJ_QMnDh8ZqqoYjiwTeLxYg">birds</a>, and even <a href="https://bioone.org/journals/african-journal-of-wildlife-research/volume-50/issue-1/056.050.0149/Mass-Die-Off-of-African-Elephants-in-Botswana--Pathogen/10.3957/056.050.0149.full">elephants</a> – and people. </p>
<p>They’ve made their way into modern culture, too. Alfred Hitchock’s movie the Birds, where birds attack residents of a California town, was inspired by birds behaving erratically due to toxic phytoplankton.</p>
<p>Despite being a source of cultural inspiration, there are many things about phytoplankton most people don’t know – such as the fact they can be seen from space. Unlike land plants which can grow 100 metres (380 feet) in height, phytoplankton individuals consist of a single cell. Individual phytoplankton can usually only be seen with a microscope, but when phytoplankton bloom, the aggregations are so large that they can be seen from satellites.</p>
<figure class="align-center ">
<img alt="An image of the ocean with a swirling blue pattern, caused by a phytoplankton bloom." src="https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397608/original/file-20210428-17-11tgoy9.jpeg?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">A phytoplankton bloom seen from space.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/ContentFeature/Phytoplankton/images/newzealand_amo_2009298.jpg">NASA/Robert Simmon and Jesse Allen</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Although they’re microscopic, phytoplankton are wonderfully diverse, with thousands (or maybe even millions) of different species and hundreds of body shapes. Some have spines or form chains to help them maintain buoyancy, while others have flagella – tiny whip-like appendages – to enable them to orient themselves in the water. Some phytoplankton are covered in CaCO₃ plates, called liths, giving them the appearance of tiny footballs, which play <a href="https://www.nature.com/articles/nclimate1753">an important role</a> in carbon sequestration.</p>
<h2>The lungs of the sea</h2>
<p>Rainforests get much of the credit for oxygen production, but phytoplankton produce at least <a href="https://science.sciencemag.org/content/291/5513/2594">50% of the Earth’s oxygen</a>. Phytoplankton are <a href="https://theconversation.com/tiny-plankton-drive-processes-in-the-ocean-that-capture-twice-as-much-carbon-as-scientists-thought-136599">the lungs of the sea</a> – the oxygen from one out of every two breaths we take comes from plankton.</p>
<p>Climate change would be <a href="https://www.pnas.org/content/117/18/9679">much more extreme</a> without phytoplankton. They use carbon dioxide from the atmosphere to fuel photosynthesis. When they die, they sink to the sea floor, locking away that carbon. Phytoplankton absorb up to <a href="https://www.nature.com/articles/s41467-020-18203-3#Sec2">50% of anthropogenic CO₂</a>, which, without them, would cause higher atmospheric CO₂ levels.</p>
<p>Nevertheless, climate change is causing changes <a href="https://www.nature.com/articles/nclimate1388">in phytoplankton communities</a>. In some places, like the North Atlantic, oceans are experiencing tropicalisation – when warming waters enable warm water plankton species to move northwards while colder water species are squeezed towards the pole. </p>
<figure class="align-center ">
<img alt="A few different types of phytoplankton under a microscope, in various shapes, with a black background." src="https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/397869/original/file-20210429-18-q06gxr.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">Under the microscope.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/diatoms-photosynthesising-algae-they-have-siliceous-1537841030">Shutterstock/Choksawatdikorn</a></span>
</figcaption>
</figure>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/tiny-plankton-drive-processes-in-the-ocean-that-capture-twice-as-much-carbon-as-scientists-thought-136599">Tiny plankton drive processes in the ocean that capture twice as much carbon as scientists thought</a>
</strong>
</em>
</p>
<hr>
<p>Some plankton in the North Atlantic have shifted northwards by over 1,000km (620 miles) in <a href="https://science.sciencemag.org/content/296/5573/1692/tab-figures-data">the past 50 years</a>. Warming seas can cause some phytoplankton to change the timing of their blooms. These changes can affect food webs, as the phytoplankton may bloom too early or late to feed the zooplankton that depend on them.</p>
<p>This is why it’s important to monitor them. There are many ways to monitor plankton, including sampling with bottles or nets, or estimating phytoplankton biomass from space using satellites. The Continuous Plankton Recorder survey has monitored plankton in the North Atlantic since 1931, using commercial vessels such as ferries and cargo ships on their normal routes to tow a one metre long recording device through the sea behind the boat.</p>
<p>The devices filter seawater through a moving band of silk, trapping the plankton. The silks are then sent to a laboratory in Plymouth, UK, to identify and count the plankton. The survey has recorded almost <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771415001596">800 taxa of plankton</a>, around 300 of which are phytoplankton. It’s created a 90-year-old record of North Atlantic plankton, allowing us to better understand the marine food web and detect changes in the marine environment caused by pollution, fishing and climate change.</p><img src="https://counter.theconversation.com/content/159955/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Abigail McQuatters-Gollop is an Associate Professor in Marine Conservation at the University of Plymouth. She is also the managing director of Ecosystem Approaches, Ltd. </span></em></p>These tiny organisms play a huge role in fighting climate change, but they’re under threat.Abigail McQuatters-Gollop, Associate Professor of Marine Conservation, University of PlymouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1365992020-05-21T12:20:41Z2020-05-21T12:20:41ZTiny plankton drive processes in the ocean that capture twice as much carbon as scientists thought<figure><img src="https://images.theconversation.com/files/335864/original/file-20200518-83388-zala49.jpg?ixlib=rb-1.1.0&rect=19%2C0%2C3176%2C2194&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ocean carbon storage is driven by phytoplankton blooms, like the turquoise swirls visible here in the North Sea and waters off Denmark.</span> <span class="attribution"><a class="source" href="https://eoimages.gsfc.nasa.gov/images/imagerecords/66000/66959/Norway.A2003178.1210.250m.jpg">NASA</a></span></figcaption></figure><p><em>The Research Brief is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>The ocean plays a major role in the global carbon cycle. The driving force comes from tiny plankton that produce organic carbon through photosynthesis, like plants on land. </p>
<p>When plankton die or are consumed, a set of processes known as the biological carbon pump carries sinking particles of carbon from the surface to the deep ocean in a process known as <a href="https://vimeo.com/322032373">marine snowfall</a>. Naturalist and writer Rachel Carson called it the “<a href="http://www.rachelcarson.org/SeaAroundUs.aspx">most stupendous snowfall on Earth</a>.” </p>
<p>Some of this carbon is consumed by sea life, and a portion is chemically broken down. Much of it is carried to deep waters, where it can remain for hundreds to thousands of years. If the deep oceans didn’t store so much carbon, the Earth would be even warmer than it is today. </p>
<p>In a recent study, I worked with colleagues from the U.S., Australia and Canada to understand <a href="https://doi.org/10.1073/pnas.1918114117">how efficiently the biological pump captures carbon</a> as part of this marine snowfall. Past efforts to answer this question often measured marine snowfall at a set reference depth, such as 450 feet (150 meters). In contrast, we paid closer attention to the depth of something called the <a href="https://www.britannica.com/science/euphotic-zone">euphotic zone</a>. This is the ocean layer close to the surface, where enough light penetrates for photosynthesis to happen. </p>
<p>We accounted more accurately for how deep the euphotic zone extends by using chlorophyll sensors, which indicate the presence of plankton. This approach revealed that the sunlit zone extends farther down in some regions of the ocean than in others. Taking this new information into account, we estimate that the biological pump carries twice as much heat-trapping carbon down from the surface ocean than previously thought.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/Y0SY21uFlpI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A recent study shows that scientists have drastically underestimated how efficiently the ocean’s biological pump moves carbon from the surface to deep waters.</span></figcaption>
</figure>
<h2>Why it matters</h2>
<p>The biological pump phenomenon takes place over the entire ocean. That means that even small changes in its efficiency could significantly change atmospheric carbon dioxide levels and, as a result, global climate. </p>
<p>Moreover, light penetration varies regionally and seasonally throughout the oceans. It’s key to understand those differences so that ocean scientists can incorporate biological processes into better global climate models.</p>
<p>We also considered another ocean phenomenon that involves the largest animal migration on Earth. It’s called <a href="https://www.cell.com/current-biology/pdf/S0960-9822(14)01067-7.pdf">diel vertical migration</a>, and happens around the globe. Every 24 hours, a massive wave of plankton and fish ascend from the twilight zone to feed at night at the surface, then descend back to darker waters in daytime. </p>
<p>Scientists think this process moves a lot of carbon from the surface to deeper waters. Our study suggests that the amount of carbon carried by these daily migrations must also be measured at the same boundary where light disappears, so that scientists can directly compare the marine snowfall to the active migration.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=548&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=548&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335842/original/file-20200518-83393-1j2jduy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=548&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Phytoplankton in the ocean consume carbon dioxide as they photosynthesize. When they are eaten or decompose, some of the carbon they contain falls into the ocean depths via a process called the biological pump.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/features/Phytoplankton/page2.php">U.S. JGOFS</a></span>
</figcaption>
</figure>
<h2>How we did it</h2>
<p>For this study, we reviewed previous research on the biological pump. To compare results, we first determined how deep the sunlit region extended. We found this boundary at the depth where it became too dark to see any more chlorophyll pigments, which mark the presence of marine phytoplankton layers. Across the studies, that depth varied between 100 and 550 feet (30 to 170 meters). </p>
<p>Next, we estimated how much organic carbon sank into deeper waters in these studies, and measured how much remained in particles that sank another 330 feet (100 meters) deeper into the twilight zone. Many creatures <a href="https://www.whoi.edu/oceanus/feature/mission-to-the-ocean-s-twilight-zone/">live and feed in these deep waters</a>, including fish, squid, worms and jellyfish. Some of them consume sinking carbon particles, reducing the amount of marine snowfall. </p>
<p>Comparing these two numbers gave us an estimate of how efficiently the biological pump was moving carbon into deep waters. The studies that we reviewed produced a wide range of values. Overall, we calculated that the biological pump was capturing twice as much carbon as previous studies that did not take into account the wide range of light penetration depths. Regional patterns also changed: Areas with shallow light penetration accounted for a higher percentage of carbon removal than areas with deeper light penetration. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/KGF4ajM0I1k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The ocean twilight zone may hold more life than all of Earth’s fisheries combined, and up to 1 million undiscovered species.</span></figcaption>
</figure>
<h2>What still isn’t known</h2>
<p>Our study reveals that scientists need to use using a more systematic approach to defining the ocean’s vertical boundaries for organic carbon production and loss. This finding is timely, because the international oceanographic community is calling for <a href="http://dx.doi.org/10.1038/d41586-020-00915-7">more and better studies</a> of the biological carbon pump and the ocean twilight zone. </p>
<p>The twilight zone could be profoundly affected if nations seek to <a href="https://www.newsdeeply.com/oceans/articles/2018/02/26/the-oceans-twilight-zone-faces-fishing-threat">develop new midwater fisheries</a>, <a href="http://dx.doi.org/10.1038/d41586-019-02242-y">mine the seafloor for minerals</a> or use it as a <a href="https://doi.org/10.3897/rio.5.e33527">dumping ground for waste</a>. Scientists are forming a collaborative effort called the Joint Exploration of the Twilight Zone Ocean Network, or <a href="http://www.jetzon.org/">JETZON</a>, to set research priorities, promote new technologies and better coordinate twilight zone studies. </p>
<p>To compare these studies, researchers need a common set of metrics. For the biological carbon pump, we need to better understand how big this flow of carbon is, and how efficiently it is transported into deeper water for long-term storage. These processes will affect how Earth responds to rising greenhouse gas emissions and the warming they cause.</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/136599/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ken Buesseler received funding for this effort from US National Aeronautics and Space Administration and the WHOI Ocean Twilight Zone project
</span></em></p>Microscopic ocean phytoplankton feed a “biological pump” that carries carbon from the surface to deep waters. Scientists have found that this process stores much more carbon than previously thought.Ken Buesseler, Senior Scientist, Woods Hole Oceanographic InstitutionLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1384362020-05-18T20:04:31Z2020-05-18T20:04:31ZClimate change threatens Antarctic krill and the sea life that depends on it<figure><img src="https://images.theconversation.com/files/335616/original/file-20200518-138639-1fyvvg1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5458%2C3641&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Brett Wilks</span></span></figcaption></figure><p>The Southern Ocean circling Antarctica is one of Earth’s richest marine ecosystems. Its food webs support an abundance of life, from tiny micro-organisms to seals, penguins and several species of whales. But climate change is set to disrupt this delicate balance.</p>
<p>Antarctic krill – finger-sized, swarming crustaceans – might be small but they underpin the Southern Ocean’s food web. Our research <a href="https://www.nature.com/articles/s41558-020-0758-4">published today</a> suggests climate change will cause the ocean habitat supporting krill growth to move south. The habitat will also deteriorate in summer and autumn.</p>
<p>The ramifications will reverberate up the food chain, with implications for other Antarctic animals. This includes humpback whales that feed on krill at the end of their annual migration to the Southern Ocean.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335617/original/file-20200518-138606-1yj761h.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">Changes in krill habitat could affect species up the food chain including the humpback whale.</span>
<span class="attribution"><span class="source">Mike Hutchings/AAP</span></span>
</figcaption>
</figure>
<h2>What we found</h2>
<p>Antarctic krill are one of the most abundant animal species in the world. About 500 million tonnes of Antarctic krill <a href="http://www.antarctica.gov.au/about-antarctica/wildlife/animals/krill">are estimated</a> to exist in the Southern Ocean.</p>
<p>Antarctic krill play a critical role in the ocean’s food webs. But their survival depends on a delicate balance of food and temperature. Scientists are concerned at how climate change may affect their population and the broader marine ecosystem.</p>
<p>We wanted to project how climate change will affect the Southern Ocean’s krill “growth habitat” – essentially, ocean areas where krill can thrive in high numbers.</p>
<p>Krill growth depends largely on ocean temperature and the abundance of its main food source, phytoplankton (microscopic single-celled plants).</p>
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<strong>
Read more:
<a href="https://theconversation.com/anatomy-of-a-heatwave-how-antarctica-recorded-a-20-75-c-day-last-month-134550">Anatomy of a heatwave: how Antarctica recorded a 20.75°C day last month</a>
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<p>Under a “business as usual” climate change scenario, future changes in ocean temperature and phytoplankton varied depending on the region and season.</p>
<p>In the mid-low latitudes, our projections showed temperatures warmed towards the limits krill can tolerate. For example, by 2100 the waters during summer around South Georgia island warmed by 1.8°C. </p>
<p>Warming water was often accompanied by decreases in phytoplankton; in the Bellingshausen Sea during summer a 1.7°C rise halved the available phytoplankton.</p>
<p>However, phytoplankton increased closer to the continent in spring and summer – most dramatically by 175% in the Weddell Sea in spring.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/334549/original/file-20200513-82375-1wsg43x.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">Antarctic krill habitat will shift south under climate change.</span>
<span class="attribution"><span class="source">Simon Payne, Australian Antarctic Division</span></span>
</figcaption>
</figure>
<h2>Shifting habitat</h2>
<p>Across all seasons, krill growth habitat remained relatively stable for 85% of the Southern Ocean. But important regional changes still occurred.</p>
<p>Krill growth habitat shifted south as suitable ocean temperatures contracted towards the poles. Combined with changes in phytoplankton distribution, growth habitat improved in spring but deteriorated in summer and autumn. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-antarctic-krill-fertilise-the-oceans-and-even-store-carbon-all-with-their-poo-125362">How Antarctic krill fertilise the oceans and even store carbon – all with their poo</a>
</strong>
</em>
</p>
<hr>
<p>This early end to the growth season could have profound consequences for krill populations. The krill life cycle is synchronised with the Southern Ocean’s dramatic seasonal cycles. Typically this allows krill to both maximise growth and <a href="http://www.antarctica.gov.au/news/2011/krill-do-it-deep-in-the-southern-ocean">reproduction</a> and store reserves to survive the winter.</p>
<p>A shift in habitat timing could create a mismatch between these two cycles. </p>
<p>For example, female krill need access to plentiful food during the summer in order to spawn. Since larger females produce exponentially more eggs, a decline in summer growth habitat could result in smaller females and far less spawning success. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335619/original/file-20200518-138615-elci8r.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">Antarctic predators including penguins rely on krill for survival.</span>
<span class="attribution"><span class="source">Royal Navy</span></span>
</figcaption>
</figure>
<h2>Why this matters</h2>
<p>Krill’s significant role in the food chain means the impacts of these changes may play out through the entire ecosystem.</p>
<p>If krill shift south to follow their retreating habitat, less food would be available for predators on sub-Antarctic islands such as Antarctic fur seals, penguins and albatrosses for whom krill forms a significant portion of the diet.</p>
<p>In the past, years of low krill densities has coincided with declines in reproductive success for these species.</p>
<p>Shifts in krill habitat timing may also affect migratory predators. For example, each year humpback whales migrate from the tropics to the poles to feed on the huge amount of summer krill. If the krill peak occurs earlier in the season, the whales must adapt by arriving earlier, or be left hungry.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=361&fit=crop&dpr=1 600w, https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=361&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=361&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=454&fit=crop&dpr=1 754w, https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=454&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/335654/original/file-20200518-83384-nsx4pe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=454&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Krill predators. a. crabeater seal (Lobodon carcinophaga), b. Adelie penguins (Pygoscelis adeliae), c. Antarctic fur seal (Arctocephalus gazella), d. humpback whale (Megaptera novaeangliae).</span>
<span class="attribution"><span class="source">Photo credits (in order a-d): Kevin Neff, Australian Antarctic Division; Mark Hindell, Institute for Marine and Antarctic Studies; Colin Lee Hong, Australian Antarctic Division; Anthony Hull, Australian Antarctic Division.</span></span>
</figcaption>
</figure>
<h2>Looking ahead</h2>
<p>Changes to krill growth habitat may damage more than the ocean food web. Demand for krill oil in health supplements and aquaculture feed is on the rise, and krill are the target of the Southern Ocean’s largest fishery. Anticipating changes in krill availability is crucial to informing the fishery’s sustainable management. </p>
<p>Many environmental drivers interact to create good krill habitat. More research is required, including better models, and an improved understanding of what drives krill to reproduce and survive. </p>
<p>But by examining changes in phytoplankton, we’ve taken significant strides towards predicting climate change impacts on krill and the wider Antarctic marine ecosystem.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-air-above-antarctica-is-suddenly-getting-warmer-heres-what-it-means-for-australia-123080">The air above Antarctica is suddenly getting warmer – here's what it means for Australia</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/138436/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Climate change is changing Antarctic krill habitat. The repercussions for the Southern Ocean food web are huge.Devi Veytia, PhD student , University of TasmaniaStuart Corney, Senior lecturer, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1313882020-04-22T20:02:10Z2020-04-22T20:02:10ZSparkling dolphins swim off our coast, but humans are threatening these natural light shows<figure><img src="https://images.theconversation.com/files/325972/original/file-20200407-160446-1tk1os6.jpg?ixlib=rb-1.1.0&rect=8%2C7%2C989%2C553&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dean Cropp</span>, <span class="license">Author provided</span></span></figcaption></figure><p>It was 2 am on a humid summer’s night on Sydney’s coast. Something in the distance caught my eye – a pod of glowing dolphins darted towards the bow of the boat. I had never seen anything like it before. They were electric blue, trailing swaths of light as they rode the bow wave.</p>
<p>It was a stunning example of “<a href="https://oceanservice.noaa.gov/facts/biolum.html">bioluminescence</a>”. The phenomenon is the result of a chemical reaction in billions of single-celled organisms called <a href="https://scripps.ucsd.edu/labs/mlatz/bioluminescence/dinoflagellates-and-red-tides/dinoflagellate-bioluminescence/">dinoflagellates</a> congregating at the sea surface. These organisms are a type of <a href="https://australianmuseum.net.au/learn/animals/plankton/phytoplankton/">phytoplankton</a> – tiny microscopic organisms many sea creatures eat. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/framing-the-fearful-symmetry-of-nature-the-years-best-photos-of-landscapes-and-living-things-122468">Framing the fearful symmetry of nature: the year's best photos of landscapes and living things</a>
</strong>
</em>
</p>
<hr>
<p>Dinoflagellates switch on their bioluminescence as a warning signal to predators, but it can also be triggered when they’re disturbed in the water – in this case, by the dolphins. </p>
<p>You can see marine bioluminescence from land in Australia. Places like <a href="https://www.abc.net.au/news/2018-08-23/jervis-bay-bioluminescence-party/10157776">Jervis Bay</a> and <a href="https://www.abc.net.au/news/2019-05-03/bioluminescence-chasers-capture-elusive-phenomenon-in-hobart/11042070?pfmredir=sm">Tasmania</a> are renowned for such spectacles.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Je1B3Xt5-lM?wmode=transparent&start=25" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>But this dazzling night-time show is under threat. <a href="https://books.google.com.au/books?hl=en&lr=&id=dEEGtAtR1NcC&oi=fnd&pg=PR5&dq=Ecological+Consequences+of+Artificial+Night+Lighting&ots=84-7c3h4iK&sig=RVMGy8qfivpIjHZu6YEtqIvnwJk&redir_esc=y#v=onepage&q&f=false">Light pollution</a> creates brighter nights and disrupts ecological rhythms along the coast, such as breeding and feeding patterns. With so much human activity close to the shore and at sea, how much longer can we continue to enjoy this natural light show?</p>
<h2>Lighting up the world has an ecological price</h2>
<p>Light pollution is a well-known problem for inland ecosystems, particularly for <a href="https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1890/1540-9295%282004%29002%5B0191%3AELP%5D2.0.CO%3B2">nocturnal species</a>. </p>
<p>In fact, a global <a href="https://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biz157/5715071">study</a> published earlier this year identified light pollution as an extinction threat to land bioluminescent species. The study surveyed firefly experts, who considered artificial light to be the second greatest threat to fireflies after habitat destruction.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325619/original/file-20200406-74261-9czbfp.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">Artificial light is one of the biggest threats fireflies face.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>At sea, artificial light pollution enters the marine environment temporarily (lights from ships and fishing activities) and permanently (coastal towns and offshore oil platforms). To make matters worse, light from cities can extend further offshore by scattering into the atmosphere and reflecting off clouds. This is known as artificial <a href="https://journals.plos.org/plosone/article/file?type=printable&id=10.1371/journal.pone.0017307">sky glow</a>.</p>
<p>For organisms with circadian clocks (day-night sleep cycles), this loss of darkness <a href="https://ore.exeter.ac.uk/repository/bitstream/handle/10871/31366/fee2014126347.pdf?sequence=1&isAllowed=y">can have damaging effects</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/329607/original/file-20200421-82707-13jr0ob.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">Bioluminescence in Sydney in the wake of the boat the author was on.</span>
<span class="attribution"><span class="source">Vanessa Pirotta</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For example it can <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503853/">disrupt animal metabolism</a>, which can lead to weight gain. Artificial light can also change <a href="https://www.sciencedirect.com/science/article/abs/pii/S1011134417302543">sea turtle</a> nesting behaviour and can disorientate turtle hatchlings when trying to get to sea, lowering their chances of survival. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lights-out-clownfish-can-only-hatch-in-the-dark-which-light-pollution-is-taking-away-120409">Lights out! Clownfish can only hatch in the dark – which light pollution is taking away</a>
</strong>
</em>
</p>
<hr>
<p>It can also <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12024">disorientate</a> the foraging of fish communities; alter <a href="https://www.ncbi.nlm.nih.gov/pubmed/27780095">predatory fish behaviour</a> (such as in Yellowfin Bream and Leatherjacks) leading to increased predation in artificial light at night; cause reproductive failure in <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2019.0272">clownfish</a>; and change the structural composition of <a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2015.0080">marine invertebrate communities</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325610/original/file-20200406-196131-br9udk.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"></a>
<figcaption>
<span class="caption">What are lights along the coast doing to bioluminescent species?</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>For zooplankton – a vital species for a range of bigger animals – artificial light <a href="https://www.imas.utas.edu.au/zooplankton/about/what-are-zooplankton">disrupts</a> their “diel vertical migration”. This term refers to the movement of zooplankton from the depths of the ocean where they spend the day to <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.2307/1939811">reduce fish predation</a>, rising to the surface at night to feed.</p>
<h2>What does this mean for bioluminescent species?</h2>
<p>Increased exposure to artificial light due to human activities, such as growing cities and increased global shipping movement, may disrupt when and where bioluminescent species hang out. </p>
<p>In turn, this may influence where predators move, leading to disruptions in the <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182826">marine food web</a>, potentially changing the dynamics of <a href="https://www.pnas.org/content/105/47/18408">energy transfer efficiency</a> between marine species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325611/original/file-20200406-74261-143jpv5.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">Bioluminescence draws tourists and photographers in Tasmania.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Bioluminescence usually serves as a communication function, such as to warn off predators, attract a mate or lure prey. For many species, light pollution in the ocean may compromise this biological communication strategy. </p>
<p>And for light-producing organisms such as dinoflagellates, excess artificial light may reduce the effectiveness of their bioluminescence because they won’t shine as bright, potentially increasing their <a href="https://www.cell.com/current-biology/pdf/S0960-9822(19)30554-8.pdf">risk of being eaten</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=820&fit=crop&dpr=1 600w, https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=820&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=820&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1031&fit=crop&dpr=1 754w, https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1031&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/329606/original/file-20200421-82684-wj6c18.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1031&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Have you read Julia Baird’s new book? It’s a great introduction to the science behind the ephemeral bioluminescence at sea.</span>
<span class="attribution"><a class="source" href="https://www.harpercollins.com.au/9781460710890/phosphorescence/">HarperCollins Australia</a></span>
</figcaption>
</figure>
<p>A 2016 <a href="https://www.nature.com/articles/srep36374.pdf">study</a> in the Arctic revealed the critical depth where atmospheric light dims to darkness, and bioluminescence from organisms becomes dominant, was approximately 30 metres below the sea surface.</p>
<p>This means any change to light in the Arctic influences when marine organisms rise to the surface. If there is too much light, these organisms remain deeper for longer where it’s safe – reducing their potential feeding time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/bright-city-lights-are-keeping-ocean-predators-awake-and-hungry-68965">Bright city lights are keeping ocean predators awake and hungry</a>
</strong>
</em>
</p>
<hr>
<h2>What can we do?</h2>
<p>Understanding the level at which artificial light penetrates the ocean is tricky, especially so when dealing with mobile sources of light pollution such as ships, which are becoming an almost <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.1987">permanent fixture</a> in some areas of the ocean.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&rect=35%2C26%2C5934%2C3947&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&rect=35%2C26%2C5934%2C3947&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325613/original/file-20200406-103690-1503ltc.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">Bioluminescence usually serves as a communication function, such as to warn off predators.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Pockets of darkness still remain in our oceans. But they are becoming rarer, making light pollution a serious global threat to marine life.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-glowing-ghost-mushroom-looks-like-it-comes-from-a-fungal-netherworld-111607">The glowing ghost mushroom looks like it comes from a fungal netherworld</a>
</strong>
</em>
</p>
<hr>
<p>The spectacle of glowing dolphins should serve as a timely reminder of our need to conserve the darkness we have left. </p>
<p><a href="https://www.darksky.org/light-pollution/light-pollution-solutions/">Simple steps</a> at home such as switching off lights and reducing unnecessary outdoor lighting, especially if you live near the ocean, is a step in the right direction to doing your bit for nocturnal species.</p><img src="https://counter.theconversation.com/content/131388/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vanessa Pirotta 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>The spectacle of glowing dolphins should serve as a timely reminder of our need to conserve the darkness we have left.Vanessa Pirotta, Marine scientist and science communicator, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1255902019-10-23T13:01:48Z2019-10-23T13:01:48ZTropical ocean bacteria help pump CO2 out of the atmosphere - new study<p>What will our climate look like in 200 years? The answer to this question depends on our emissions of greenhouse gases, but also on all the complex and interlinked physical and biological processes that make up the climate system. One of these processes has a surprising source: tiny bacteria living in tropical oceans. <a href="https://www.nature.com/articles/s41467-019-12549-z">Our latest research</a> shows how important some special bacteria, called nitrogen fixers, are to the global process of pulling carbon dioxide (CO₂) out of the atmosphere.</p>
<p>The story begins with another type of single-celled microbe known as phytoplankton. Like plants, phytoplankton create their own food using sunlight and CO₂, absorbing much of the CO₂ as they grow. When they die, they sink to the deep ocean, taking the CO₂ with them.</p>
<p>The constant removal of CO₂ from the air to the surface of the water and then to the deep ocean is termed the “<a href="https://www.us-ocb.org/biological-pump/">biological pump</a>”. The stronger the collective biological pump action of phytoplankton, the less CO₂ in the atmosphere and the cooler the planet.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/298092/original/file-20191022-28133-vb48o7.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 cold ocean of an Ice Age drew carbon dioxide out of the atmosphere.</span>
<span class="attribution"><span class="source">Pearse J. Buchanan</span></span>
</figcaption>
</figure>
<p>The cold climate of the Earth’s ice ages was due in part to a <a href="https://www.sciencedirect.com/science/article/pii/B9780080959757006185?via%253Dihub">more vigorous biological pumping</a>. At these times, global temperatures were 5°C lower than today. Glaciers covered the Siberian, European and North American landmasses, and sea level dropped more than 100 metres. These extreme conditions were brought about by a decline in atmospheric CO₂ of about 100 parts per million.</p>
<p>We know that <a href="https://theconversation.com/carbon-dioxide-trapped-by-ice-age-oceans-raises-questions-for-future-81070">the ocean absorbed the CO₂</a>, and that the increase in drawdown came partly from a change in <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016PA003024">ocean circulation</a>. The ability of the ocean to hold CO₂ depends on how it circulates, with some modes of circulation enabling more storage than others. But this only explains between <a href="https://www.clim-past.net/12/2271/2016/">a third</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0012821X17302753">two-thirds</a> of the CO₂ drawdown. The rest was due to a strengthening of the biological pump. </p>
<h2>Dust and nitrogen fixers</h2>
<p>For years, scientists have tried to explain this strengthening by looking at what happened to cold-water phytoplankton living in places such as the Southern Ocean. This ocean tends to be starved of iron, a nutrient essential for photosynthesis. The climate during the ice ages contained a lot of iron-rich dust, so there is <a href="https://www.princeton.edu/news/2014/03/21/dust-wind-drove-iron-fertilization-during-ice-age">strong evidence</a> that this stimulated the growth of cold-water phytoplankton.</p>
<p>But recent <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL064250">climate modelling</a> has shown that fertilisation of the Southern Ocean with iron didn’t lead to enough CO₂ absorption to explain the ice ages. So, along with our colleagues <a href="https://theconversation.com/profiles/steven-phipps-91100">Steven Phipps</a> and <a href="https://theconversation.com/profiles/nathan-bindoff-593745">Nathan Bindoff</a>, we investigated the role of phytoplankton that live in the warm, tropical ocean.</p>
<p>Tropical phytoplankton tend to be <a href="https://www.eurekalert.org/pub_releases/2013-04/nocs-ona041013.php">starved of nitrogen</a>, not iron. But these waters also contain a special group of bacteria that can “fix” nitrogen, turning nitrogen gas into forms that can be used by living things. The presence of nitrogen-fixing bacteria therefore fertilises warm-water phytoplankton, enabling their growth and strengthening the biological pump.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/297919/original/file-20191021-56234-17cp11t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A dust storm blows over the Atlantic Ocean.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/2137">NASA</a></span>
</figcaption>
</figure>
<p>But much like cold-water phytoplankton, nitrogen fixers also need iron. In fact, nitrogen fixation is an iron-hungry process, and colonies made up of millions of nitrogen fixers <a href="https://static-content.springer.com/esm/art%253A10.1038%252Fngeo1181/MediaObjects/41561_2011_BFngeo1181_MOESM298_ESM.wmv">work together</a> to capture and extract the iron from dust particles. Realising the potential of nitrogen fixers, we added them to an ocean climate model and found that they played a pivotal role in strengthening the biological pump when the ocean is fertilised with iron, as during the ice ages.</p>
<p>This finding reveals how the biological pump could have been strengthened everywhere, in both the Southern Ocean and the tropics. Only a global view of the biological pump can explain the full drawdown of CO₂ during the ice ages.</p>
<h2>Climate change today</h2>
<p>Given our current need to reduce the amount of CO₂ in the atmosphere, it may seem <a href="https://blog.nationalgeographic.org/2012/10/18/iron-fertilization-savior-to-climate-change-or-ocean-dumping/">tempting</a> to try fertilising the ocean with iron in order strengthen the biological pump again. Realistically, a lot more research would need to be done to determine the potential and the risks of this action. </p>
<p>But even if we don’t try to geoengineer the planet, changes in the biological pump may be coming our way. There is <a href="https://phys.org/news/2013-12-deep-sea-corals-long-term-shift-pacific.html">some evidence</a> that nitrogen fixation has been increasing since the industrial revolution, a sign of a strengthening biological pump.</p>
<p>One thing is clear, the biological pump will help determine the long-term trajectory of Earth’s climate. If (and hopefully when) we stop our emissions, the biological pump will come to the forefront as a major control of atmospheric CO₂. How it responds will either amplify or ameliorate our greenhouse problem, and so it is imperative that we continue to build our understanding.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&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><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1125590">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/125590/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pearse James Buchanan received funding from an Australian Postgraduate Fulbright award and receives funding from the Natural Environmental Research Council (NERC) in the United Kingdom.</span></em></p><p class="fine-print"><em><span>Richard Matear receives funding from CSIRO. </span></em></p><p class="fine-print"><em><span>Zanna Chase receives funding from the Australian Research Council</span></em></p>Nitrogen-fixing bacteria help tropical phytoplankton absorb carbon dioxide, creating a biological pump in the oceans.Pearse James Buchanan, Postdoctoral Researcher in Biological Oceanography, University of LiverpoolRichard Matear, Climate Prediction Group Leader, CSIROZanna Chase, Associate professor, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1243282019-09-27T14:53:27Z2019-09-27T14:53:27ZOcean ecosystems take two million years to recover after mass extinction – new research<figure><img src="https://images.theconversation.com/files/294564/original/file-20190927-185369-1dgaqhm.jpg?ixlib=rb-1.1.0&rect=18%2C657%2C4160%2C2895&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A phytoplankton bloom stretching across the Barents Sea off the coast of mainland Europe's most northern point.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Phytoplankton_bloom_captured_by_Envisat.jpg">European Space Agency</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Around 66m years ago, a giant asteroid struck the Earth, causing the <a href="https://science.sciencemag.org/content/327/5970/1214">extinction of the dinosaurs</a>, ammonites, and many other species.</p>
<p>The asteroid was equally devastating at a microscopic level, <a href="https://pubs.geoscienceworld.org/gsa/geology/article-abstract/33/8/653/103785">driving ocean plankton</a> to near-extinction. This crippled the base of the marine food chain and shut down important ocean functions, such as <a href="https://pubs.geoscienceworld.org/gsa/geology/article/44/4/287/132044/partial-collapse-of-the-marine-carbon-pump-after">the absorption and delivery of carbon dioxide</a> from the atmosphere to the ocean floor.</p>
<p>Given the <a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">real threat of a sixth mass extinction event</a> brought about by human-caused climate breakdown and habitat disruption, we wanted to find out how long the ocean ecosystem took to reboot after the last one. What we found has grave implications for the long-term outlook of marine ecosystems should we tip the critical base of its food chain over the threshold of extinction.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">Earth's sixth mass extinction has begun, new study confirms</a>
</strong>
</em>
</p>
<hr>
<p>The nannoplankton almost totally wiped out 66m years ago – also known as <a href="https://www.palaeontologyonline.com/articles/2018/fossil-focus-calcareous-nannofossils-the-best-things-are-microscopic/">coccolithophores</a> – are now widespread once more in the sunlit upper oceans. Although roughly 100 times smaller than a grain of sand, they are so abundant that they are <a href="https://www.wired.com/2010/08/phytoplankton-blooms-gallery/">visible from space as swirling blooms</a> in the ocean surface.</p>
<p>When these microscopic plankton die, they leave behind exquisite armoured <a href="http://www.mikrotax.org/Nannotax3/index.php?id=315">exoskeletons known as coccospheres</a> made from the mineral calcite, composed of bonded calcium and carbon. Along with the dead plankton cells, these skeletons slowly fall to the ocean floor, forming a muddy calcium and carbon-rich sediment. As this sediment compacts, it forms chalk and limestone, leaving us with iconic landscapes such as <a href="https://youtu.be/Ep5tcBXyFoE">white chalk cliffs</a> – the shallow sea floor of a forgotten age, since lifted up by tectonic activity.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/294553/original/file-20190927-185403-1109usc.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 white chalk cliffs of England’s coast contain within them millions of years of plankton history.</span>
<span class="attribution"><span class="source">Jeremy Young</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Conserved within this compacted sediment is a continuous fossil record stretching back 220m years. It is this fossil record – the <a href="http://disq.us/t/3iipu4d">most abundant on the planet</a> – that can tell us how ecosystems responded to the extinction of nannoplankton. Changes in the diversity and abundance of the plankton that once lived in the ocean above reflect the environmental changes that played out in the millennia after the giant asteroid hit.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sea-plankton-shells-hold-key-to-millions-of-years-of-climate-data-19589">Sea plankton shells hold key to millions of years of climate data</a>
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</em>
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<hr>
<p>We extracted a continuous <a href="http://www-odp.tamu.edu/publications/198_IR/chap_05/chap_05.htm">core</a> of deep-sea sediment from the Pacific Ocean. For the first 13m years after the <a href="http://www-odp.tamu.edu/publications/198_IR/chap_05/c5_f4.htm">mass extinction</a> event, we took a sample of the fossil record at intervals of 13,000 years. We measured fossil abundance, diversity and cell sizes from over 700,000 specimens, producing probably the largest fossil dataset ever produced from a single site.</p>
<h2>2m years for stability, 10m for diversity</h2>
<p>These <a href="http://disq.us/t/3iipu4d">fossil data</a> revealed that the plant-like, photosynthetic plankton bounced back almost immediately - probably within a few thousand years after the mass extinction. However, the earliest communities were highly unstable and made up of just a handful of species with unusually small cell sizes, as the figure above shows.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1089&fit=crop&dpr=1 600w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1089&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1089&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1369&fit=crop&dpr=1 754w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1369&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/294568/original/file-20190927-185399-jxq0xs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1369&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tiny interlocking discs combine to produce microplankton’s calcite shells. Species that survived the asteroid impact were much bigger than new species that emerged in the place of those that were wiped out.</span>
<span class="attribution"><span class="source">Paul Bown/UCL</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While the calcite skeletons of larger plankton cells can <a href="https://www.mdpi.com/2071-1050/10/3/869">sink to the sea floor</a>, the skeletons of these smaller organisms descend much less often, instead getting “recycled” in the upper ocean by hungry plankton. Communities with larger cell sizes were not reestablished until two million years later, restoring their critical transfer of carbon to the ocean floor to <a href="https://pubs.geoscienceworld.org/gsa/geology/article/44/4/287/132044/partial-collapse-of-the-marine-carbon-pump-after">pre-extinction levels</a>.</p>
<p>By this time, the number of different plankton species had also increased. This genetic diversity allowed them to expand into a greater range of ocean habitats, providing greater resilience to environmental change, and a secure foundation at the base of the ocean food web. </p>
<p>This stability then supported expansion in the abundance and diversity of larger plankton, fish, mammals, and birds dependent on these food sources. But although stable and resilient ecosystems had returned by two million years after the mass extinction, it took a further eight million years for species numbers to fully recover to their previous levels.</p>
<h2>A warning from the past</h2>
<p>Today’s marine ecosystems are still just as dependent on the plankton at their base as they were in the past. Studies show that populations of modern-day plankton have already <a href="https://www.nature.com/articles/nature09268">declined by as much as 40%</a>, and that 70% of species are <a href="https://www.pnas.org/content/113/11/2964">migrating towards the poles</a>. We still don’t fully understand how plankton species might finally be driven to extinction, but the fossil record shows us that <a href="https://science.sciencemag.org/content/332/6027/349">extinction is strongly shaped by climate change</a>.</p>
<p>If we carry on emitting carbon and interfering with marine ecosystems, we run the risk of losing one of its critical carbon-storing and food-providing players. Research shows that that could take nature millions of years to reverse. </p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/263883/original/file-20190314-28475-1mzxjur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&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><a href="https://theconversation.com/imagine-newsletter-researchers-think-of-a-world-with-climate-action-113443?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=Imagineheader1124328">Click here to subscribe to our climate action newsletter. Climate change is inevitable. Our response to it isn’t.</a></em></p><img src="https://counter.theconversation.com/content/124328/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Bown receives funding from University College London and the Natural Environment Research Council (NERC).
</span></em></p><p class="fine-print"><em><span>Samantha Gibbs receives funding from The Royal Society, the University of Southampton and the Natural Environment Research Council. </span></em></p><p class="fine-print"><em><span>Sarah Alvarez receives funding from the European Union's Environment Research Council (NERC).</span></em></p>Populations of plankton are in decline. If we push this critical foundation of the marine food chain to extinction, we could cripple ecosystems for millions of years.Paul Bown, Professor of Micropalaeontology, UCLSamantha Gibbs, Lecturer, National Oceanography Centre, University of SouthamptonSarah Alvarez, Lecturer in Life and Earth Sciences, University of GibraltarLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1226022019-09-17T21:29:42Z2019-09-17T21:29:42ZHuge sharks, tiny plankton: Exploring the changing Arctic from an icebreaker<figure><img src="https://images.theconversation.com/files/292891/original/file-20190917-19040-1b5a8wa.png?ixlib=rb-1.1.0&rect=68%2C48%2C1704%2C824&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A camera catches a huge Greenland shark in eastern Baffin Bay, near Disko Bay, Greenland. </span> <span class="attribution"><span class="source">Jonathan Fisher</span>, <span class="license">Author provided</span></span></figcaption></figure><p>“You’re going to need a bigger boat.”</p>
<p>That famous line from the 1975 film <em>Jaws</em> makes me smile for a couple of reasons as I wrap up 26 days aboard Canada’s largest research icebreaker, the Canadian Coast Guard Ship (CCGS) Amundsen.</p>
<p>First, I have been collecting new video data to understand the distribution, abundance and behaviours of the <a href="https://www.sciencedirect.com/science/article/pii/S0022098112001657">largest, slowest</a> and <a href="https://science.sciencemag.org/content/353/6300/702">oldest fish</a> in Arctic waters — the elusive Greenland shark.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/caught-on-camera-ancient-greenland-sharks-90584">Caught on camera: Ancient Greenland sharks</a>
</strong>
</em>
</p>
<hr>
<p>Second, although shark science was one of many mission objectives achieved during these past four weeks, thankfully, we did not need a bigger boat. The 98-metre-long CCGS Amundsen comfortably accommodated 41 crew, 34 scientists and allowed us to safely complete more than 250 scientific operations at sea, across 4,589 nautical miles (about 8,500 kilometres) between Resolute, Nunavut and Québec City. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292692/original/file-20190916-19076-1ipzya9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&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 route between Resolute and Québec City.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The dedicated science mission of the Amundsen provides an unequalled opportunity to collect baseline data and <a href="https://oceansnorth.org/en/canada-arctic-marine-atlas/">characterize the dynamics within the rapidly changing eastern Canadian Arctic and sub-Arctic marine regions</a>. </p>
<h2>One ship, many goals</h2>
<p>The scientific objectives for this Arctic mission were far-ranging. Collectively, our research covered more than three months — from May 30 to Sept. 10, 2019 — and involved more than 150 scientists at sea. </p>
<p>Throughout the water column, scientists dropped oceanographic sensors and programmed bottles to collect water samples to quantify the physical conditions and nutrients needed to fuel the tiny marine plants called phytoplankton at the base of marine food webs. </p>
<p>Nets, lowered as deep as 2,000 metres, or towed near the surface, captured the zooplankton and small fishes that consume that phytoplankton. Sometimes sleep waited until the next transit, as these operations were repeated nearly non-stop under the midnight sun to maximize our time at each sampling station. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1067&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1067&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1067&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1340&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1340&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292693/original/file-20190916-19049-1h3zgx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1340&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The ‘Monster Net’ was lowered below the ship and collected zooplankton and small fishes.</span>
<span class="attribution"><span class="source">Jonathan Fisher</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>At the seabed, boxcores scooped up mud as well as sea stars and other organisms living in and on the bottom of the seafloor. Larger nets collected fish, allowing scientists to estimate fish abundances and biodiversity that will contribute to the assessments of Arctic fisheries and their ecosystems, and give scientists and policy-makers a better idea of what’s in the ocean and how it’s changing. </p>
<p>All this biological work was complimented by high-resolution seafloor mapping that will help vessels navigate and identify submarine geohazards near northern communities. Many expect more ship traffic in the Arctic as the sea ice thins and melts, even though the charts are currently inadequate and extensive shallow areas are poorly mapped. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-ice-recedes-the-arctic-isnt-prepared-for-more-shipping-traffic-102312">As ice recedes, the Arctic isn't prepared for more shipping traffic</a>
</strong>
</em>
</p>
<hr>
<p>Geologists pulled sediment cores from the sea floor that will reveal the geologic history of the Arctic. Scientists on board also looked for traces of human influence in the Arctic, with a focus on contaminants, such as organic pollutants and plastics in the water and marine species, and tried to decipher the potential impacts of oil spills on the Arctic ecosystem. </p>
<h2>Big fish, old fish, small fish, young fish</h2>
<p>As a fisheries scientist, this mission has been somewhat of a study in contrasts for me. Much of my (and my camera’s) focus has been on long, old Greenland sharks that can <a href="https://www.doi.org/10.1126/science.aaf1703">reach lengths greater than six metres and live for more than 270 years</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/q9gpjxMBhFo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A Greenland shark swims up to our team’s baited remote underwater video lander in July 2019.</span></figcaption>
</figure>
<p>The video system allows us to identify individuals and the number of sharks locally <a href="https://www.nature.com/articles/s41598-017-19115-x">without the use of hooks or nets</a>, and to reveal their habitats and <a href="https://doi.org/10.1007/s00300-019-02520-5">determine what other species they interact with</a>. </p>
<p>But I have spent as much time on the Amundsen working with a team from Laval University quantifying the composition, abundances and distributions of zooplankton and fishes. We hauled five types of sampling nets deployed 70 times on a 24-hour schedule. It was, at times, exhausting work made easier by dedicated colleagues and great meals. </p>
<p>That has meant sorting, measuring and photographing thousands of tiny larval fish whose numbers and characteristics will set the stage for future adult populations. </p>
<p>One focus has been on the Arctic cod, a species whose superabundance and dominance across Arctic waters makes it a key link in the food chain between its zooplankton prey and marine mammals, birds and larger fishes that all serve as its predators. </p>
<p>Arctic cod are key to the survival of many Arctic species, yet it is also sensitive to changing environmental conditions. Understanding the dynamics of Arctic cod within the upper, sun-lit surface waters is important for forecasting changes to the structure and functioning of marine ecosystems across these waters in the future. </p>
<p>The detection of southern species in Arctic waters is one obvious indicator of change, but characterizing their interactions with resident species is one wild card dealt by changing ocean conditions. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292695/original/file-20190916-19030-g2ib3y.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">Larval Arctic cod, 18 mm long.</span>
<span class="attribution"><span class="source">Cyril Aubry</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The eastern Canadian Arctic is changing at a rapid pace in a national or global context, leading to new conditions faced by northern communities and ecosystems. </p>
<p>There is a <a href="http://www.arcticnet.ulaval.ca/pdf/media/29170_IRIS_East_full%20report_web.pdf">growing scientific base of information in this region that can be used to inform decisions and policy</a>. But new questions are emerging about transportation, fisheries, diversity and oceanographic changes, and their impacts on Arctic communities and industries. For me, this mission has demonstrated the need, and opportunity, to tackle so many research questions at once. </p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&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/122602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan A. D. Fisher receives funding from the ArcticNet Network of Centres of Excellence in Canada (<a href="http://www.arcticnet.ulaval.ca">www.arcticnet.ulaval.ca</a>) and the Ocean Frontier Institute (OFI; <a href="http://www.oceanfrontierinstitute.com">www.oceanfrontierinstitute.com</a>). The OFI was established within the Canada First Research Excellence Fund. </span></em></p>The eastern Arctic and sub-Arctic marine areas of Canada are changing rapidly under climate change.Jonathan A. D. Fisher, Research scientist, Memorial University of NewfoundlandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1214432019-08-26T19:59:43Z2019-08-26T19:59:43ZAcid oceans are shrinking plankton, fuelling faster climate change<figure><img src="https://images.theconversation.com/files/289408/original/file-20190826-8893-1l0g6t8.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers investigated how acidic oceans affect plankton in Prydz Bay, East Antarctica.</span> <span class="attribution"><span class="source">Daniel A. Nielsen</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Increasingly acidic oceans are putting algae at risk, threatening the foundation of the entire marine food web. </p>
<p>Our research into the effects of CO₂-induced changes to microscopic ocean algae – called phytoplankton – was published today in <a href="https://www.nature.com/articles/s41558-019-0557-y">Nature Climate Change</a>. It has uncovered a previously unrecognised threat from ocean acidification.</p>
<p>In our study we discovered increased seawater acidity reduced Antarctic phytoplanktons’ ability to build strong cell walls, making them smaller and less effective at storing carbon. At <a href="https://www.nature.com/articles/nature04095">current rates of seawater acidification</a>, we could see this effect before the end of the century.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ocean-acidification-is-already-harming-the-great-barrier-reefs-growth-55226">Ocean acidification is already harming the Great Barrier Reef's growth</a>
</strong>
</em>
</p>
<hr>
<h2>What is ocean acidification?</h2>
<p>Carbon dioxide emissions are not just altering our atmosphere. More than 40% of CO₂ emitted by people is <a href="https://science.sciencemag.org/content/305/5682/367.full">absorbed by our oceans</a>.</p>
<p>While reducing the CO₂ in our atmosphere is generally a good thing, the ugly consequence is this process makes seawater more acidic. Just as placing a tooth in a jar of cola will (eventually) dissolve it, increasingly acidic seawater has a devastating effect on organisms that build their bodies out of calcium, like corals and shellfish.</p>
<p>Many studies to date have therefore taken the perfectly logical step of studying the effects of seawater acidification on these “calcifying” creatures. However, we wanted to know if other, non-calcifying, species are at risk. </p>
<h2>Diatoms in our oceans</h2>
<p>Phytoplankton use photosynthesis to turn carbon in the atmosphere into carbon in their bodies. We looked at diatoms, a key group of phytoplankton responsible for 40% of this process in the ocean. Not only do they remove huge amounts of carbon, they also fuel entire marine food webs. </p>
<p>Diatoms use dissolved silica to build the walls of their cells. These dense, glass-like structures mean diatoms sink more quickly than other phytoplankton and therefore increase the transfer of carbon to the sea floor where it may be stored for millennia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289409/original/file-20190826-8885-9v5bnr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diatoms are microscopic plant plankton that collectively remove huge amounts of carbon from the atmosphere.</span>
<span class="attribution"><span class="source">Alyce M. Hancock</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This makes diatoms major players in the global carbon cycle. That’s why our team decided to look at how climate-change-driven ocean acidification might affect this process.</p>
<p>We exposed a natural Antarctic phytoplankton community to increasing levels of acidity. We then measured the rate at which the whole community used dissolved silica to build their cells, as well as the rates of individual species within the community.</p>
<h2>More acid means less silicone</h2>
<p>The more acidic the seawater, the more the diatom communities were made up of smaller species, reducing the total amount of silica they produced. Less silica means the diatoms aren’t heavy enough to sink quickly, reducing the rate at which they float down to the sea bed, safely storing carbon away from the atmosphere.</p>
<p>On examining individual cells, we found many of the species were highly sensitive to increased acidity, reducing their individual silicification rates by 35-80%. These results revealed not only are communities changing, but species that remain in the community are building less-dense cell walls.</p>
<p>Most alarming, many of the species were affected at ocean pH levels predicted for the end of this century, adding to a growing body of evidence showing significant ecological implications of climate change will take effect much sooner than previously anticipated.</p>
<h2>Marine diversity is in decline</h2>
<p>These losses in silica production could have far reaching consequences for the biology and chemistry of our oceans.</p>
<p>Many species affected are also an important component of the diet of the Antarctic krill, which is central to the Antarctic marine food web.</p>
<p>Fewer diatoms sinking to the ocean floor mean significant changes in silicon cycling and carbon burial. In a time when carbon drawn down by our ocean is crucial to helping sustain our atmospheric systems, any loss from this process will exacerbate CO₂ pollution.</p>
<p>Our new research adds yet another group of organisms to the list of climate change casualties. It emphasises the urgent need to reduce our dependency on fossil fuels. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-acid-oceans-will-dissolve-coral-reef-sands-within-decades-86826">Our acid oceans will dissolve coral reef sands within decades</a>
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</em>
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<p>The only course of action to prevent catastrophic climate change is to stop emitting CO₂. We need to cut our emissions soon, if we hope to keep our oceans from becoming too acidic to sustain healthy marine ecosystems.</p><img src="https://counter.theconversation.com/content/121443/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katherina Petrou receives funding from the Australian Antarctic Division. </span></em></p><p class="fine-print"><em><span>Daniel Nielsen 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>Acidic oceans are disrupting a major part of the carbon cycle, slowing how seas absorb carbon from the atmosphere. This could massively speed up the effects of climate change.vKatherina Petrou, Senior Lecturer in Phytoplankton Ecophysiology, University of Technology SydneyDaniel Nielsen, Casual Academic, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1174932019-05-23T13:24:08Z2019-05-23T13:24:08ZPlastic poisons ocean bacteria that produce 10% of the world’s oxygen and prop up the marine food chain<figure><img src="https://images.theconversation.com/files/276093/original/file-20190523-187189-sugo96.jpg?ixlib=rb-1.1.0&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/plastic-bag-floating-underwater-surrounded-by-183344285?src=0xrwP3_-VEgdhdIEBlNZeQ-1-37">Richard Whitcombe/Shutterstock</a></span></figcaption></figure><p>We’ve all seen the impact of our plastic addiction. It’s hard to miss the devastating images of whales and sea birds that have died with their stomachs full of <a href="https://theconversation.com/plastic-warms-the-planet-twice-as-much-as-aviation-heres-how-to-make-it-climate-friendly-116376">solidified fossil fuels</a>. The recent discovery of a plastic bag in the <a href="https://news.nationalgeographic.com/2018/05/plastic-bag-mariana-trench-pollution-science-spd/">Mariana Trench</a>, at over 10,000 metres below sea level, reminds us of the depth of our problem. Now, the breadth is increasing too. New research suggests that chemicals leaching from the bags and bottles that pepper our seas are harming tiny marine organisms that are central to sustained human existence.</p>
<p>Once plastic waste is out in the open, waves, wind and sunlight cause it to break down into smaller pieces. This fragmentation process releases chemical additives, originally added to imbue useful qualities such as rigidity, flexibility, resistance to flames or bacteria, or a simple splash of colour. Research has shown that the presence of these chemicals in fresh water and drinking water can have <a href="http://ec.europa.eu/environment/chemicals/endocrine/definitions/affect_en.htm%20https://www.who.int/ceh/publications/endocrine/en/">grave effects</a>, ranging from reduced reproduction rates and egg hatching in fish, to hormone imbalances, reduced fertility or infertility, cardiovascular diseases, diabetes and cancer in humans.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/plastic-warms-the-planet-twice-as-much-as-aviation-heres-how-to-make-it-climate-friendly-116376">Plastic warms the planet twice as much as aviation – here's how to make it climate-friendly</a>
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<p>But very little research has looked at how these additives might affect life in our oceans. To find out, researchers at Macquarie University prepared seawater contaminated with differing concentrations of chemicals leached from plastic bags and <a href="https://www.bpf.co.uk/plastipedia/polymers/PVC.aspx">PVC</a>, two of the most common plastics in the world. They then measured how living in such water affected the most abundant photosynthesising organism on Earth – <em>Prochlorococcus</em>. As well as being a critical foundation of the oceanic food chain, they produce 10% of the world’s oxygen.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/276104/original/file-20190523-187185-1ffaorq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Prochlorococcus</em> are miniscule, but there are as many of them in the oceans as there are atoms in a ton of gold.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/prochlorococcus/sets/72157613990334681">Chisholm Lab/Flickr</a></span>
</figcaption>
</figure>
<p>The results indicate that the scale and potential impacts of plastic pollution may be far greater than most of us had imagined. They <a href="https://www.nature.com/articles/s42003-019-0410-x">showed</a> that the chemical-contaminated seawater severely reduced the bacteria’s rate of growth and oxygen production. In most cases, bacteria populations actually declined.</p>
<h2>What can be done?</h2>
<p>Given the importance of oxygen levels to the rate of <a href="https://www.smithsonianmag.com/science-nature/earths-oxygen-levels-can-affect-its-climate-180955572/#juU6gcJuVvbeGOiM.99">global heating</a>, and the vital role these phytoplankton play in ensuring thriving marine ecosystems, it is essential that we now conduct research outside of the laboratory into the effects of plastic additives on bacteria in the open seas. In the meantime, we need to take active steps to reduce the risks of chemical plastic pollution.</p>
<p>The clear first step is to reduce the amount of plastic entering the ocean. Recent <a href="http://europa.eu/rapid/press-release_IP-19-2631_en.htm">EU</a> and <a href="https://www.theguardian.com/environment/2019/may/22/england-plastic-straws-ban">UK</a> bans on single-use plastics are a start, but much more radical policies are needed now to reduce the role plastic plays in our lives as well as to stop the plastic we do use being released into waterways and dramatically improve <a href="https://www.nationalgeographic.com/magazine/2018/06/plastic-planet-waste-pollution-trash-crisis/">appallingly low</a> recycling rates.</p>
<p>At an international level, we must make addressing the waste produced by the <a href="https://www.nature.com/articles/s41598-018-22939-w">fishing industry</a> a priority. Broken fishing nets alone account for almost half of the plastic in the <a href="https://news.nationalgeographic.com/2018/03/great-pacific-garbage-patch-plastics-environment/?beta=true">Great Pacific Garbage Patch</a> – and lost or discarded fishing gear accounts for <a href="https://ec.europa.eu/fisheries/new-proposal-will-tackle-marine-litter-and-%E2%80%9Cghost-fishing%E2%80%9D_it">one-third</a> of the plastic litter in European seas. EU incentives <a href="http://europa.eu/rapid/press-release_IP-19-2631_en.htm">announced</a> in 2019 to tackle this waste do not go far enough.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/276102/original/file-20190523-187182-1cs80xl.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">Discarded fishing nets and other fishing gear make up a significant proportion of the plastic in our oceans.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ghost-fishing-net-discarded-by-fishermen-236718586?src=RzdoqH9BrWr0lWihw_f_BQ-1-5">Aqua Images/Shutterstock</a></span>
</figcaption>
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<p>Legislation is also urgently needed to limit the industrial use of harmful chemical additives to a level that is absolutely necessary. As an example, <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/bisphenol-a">bisphenol A</a>, found in myriad products ranging from receipt paper to rubber ducks, is now listed as a “<a href="https://echa.europa.eu/candidate-list-table">substance of very high concern</a>” due to its hormone-disrupting effects. But as yet the few existing laws regulating the chemical do not cover the majority of industrial use. This needs to change – as quickly as possible.</p>
<p>Of course, even if we can completely stop new chemicals from reaching the oceans, we will still have a legacy of plastic and associated chemical pollution to deal with. At the moment, we have no idea whether we’ve already done irreversible damage, or if marine ecosystems are resilient to current levels of plastic pollution in the open oceans. But the health of our oceans is not something we can risk. So, in addition to physical removal schemes such as <a href="https://www.theoceancleanup.com/">The Ocean Clean Up</a>, we need to invest in chemical removal technologies as well.</p>
<p>In salty ocean environments, such technologies are under-researched. We are currently in the early stages of developing a floating device that uses a small electric circuit to transform BPA into easily retrievable solid matter, but our work alone is not enough. Scientists and governments need to ramp up their efforts to both understand and eliminate the problem of chemical contamination of our oceans, before it’s too late. </p>
<p>While ocean bacteria may seem far removed from our daily lives, we are dependent on these tiny organisms to maintain the balance of our ecosystems. We ignore their plight at our peril.</p><img src="https://counter.theconversation.com/content/117493/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Petra Cameron receives funding from the UK Research Councils. </span></em></p><p class="fine-print"><em><span>Philippa Kearney receives funding from the EPSRC. </span></em></p>New research shows that chemicals leached from ocean plastic impair the growth and oxygen production of the planet’s most abundant photosynthesiser - endangering marine ecosystems and the climate.Petra Cameron, Senior Lecturer in Chemistry, University of BathPhilippa Kearney, PhD Researcher, University of BathLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1148442019-04-11T14:12:45Z2019-04-11T14:12:45ZHow microscopic ocean organisms and the earth’s temperature are linked<figure><img src="https://images.theconversation.com/files/268385/original/file-20190409-2905-eoiquw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Phytoplankton under a microscope.</span> <span class="attribution"><span class="source">Rattiya Thongdumhyu/Shutterstock</span></span></figcaption></figure><p>The global ocean covers <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/global-ocean">about 71%</a> of the earth’s surface and contains <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/global-ocean">approximately 97%</a> of all water on the planet. </p>
<p>In some ways, the ocean is more important now than it ever has been before. The planet <a href="https://climate.nasa.gov/evidence/">is warming</a> and more carbon dioxide is being <a href="https://www.newscientist.com/article/2191881-carbon-dioxide-levels-will-soar-past-the-410-ppm-milestone-in-2019/">released into the atmosphere</a>. The ocean is the biggest absorber of carbon dioxide from the atmosphere. Its carbon dioxide absorption far surpasses the uptake by all forests combined on planet earth.</p>
<p>The amount of carbon dioxide that the ocean can take up depends on the temperatures of the waters. Cold waters absorb more carbon, while warmer waters take up less. This happens through a biological process that sees carbon dioxide from the atmosphere dissolved in the surface waters of the sunlit upper ocean, then pumped into deeper water layers and the ocean floor. </p>
<p>But there’s more to it than just water temperature. Microscopic organisms known as <a href="https://oceanservice.noaa.gov/facts/phyto.html">phytoplankton</a> are the main drivers of this “biological pump” process. For my PhD, I’m <a href="https://www.researchgate.net/publication/332275411_Microbe-nutrient_interactions_in_the_Agulhas_System_Climate_Array_marine_system">researching</a> these phytoplankton communities and their interactions with nutrients within ocean systems. I want to understand how the biological pump is working within the Agulhas marine system, a marine region between East London and Port Elizabeth in South Africa.</p>
<p>The Agulhas system is a hot spot for fisheries and aquaculture industries that feed billions of people across the world. The region is also responsible for regulating Southern Africa’s climate and weather. Understanding how the system works in a warming planet allows us to predict how the ocean will be in the future. </p>
<p>It is also important for advising policy makers and guiding industries on which parts are most productive at what times of the year as the region is very dynamic and varies from season to season. </p>
<p>With the use of nitrogen isotopes, my research is part of a growing body of work that’s trying to understand the dynamics of the ocean, and the role it plays in global warming and overall, global climate change mitigation. Over and above my work is uncovering the role that the ocean plays in regulating the Earth’s temperature and therefore making our planet habitable.</p>
<h2>Phytoplankton</h2>
<p>Phytoplankton vary in size and shape; their physiological makeups enable diverse environmental specialisation. This means that different types of phytoplankton can be found in diverse ocean environments depending on geography, temperature, salinity, pH and nutrients availability. </p>
<p>Phytoplankton are primary producers of the marine ecosystem. This means that the marine food web primarily depends on phytoplankton. They also photosynthesise like land’s primary producers, plants. They take up carbon dioxide to manufacture their own foods and are responsible for giving off about more than half of the oxygen that animals need to breathe back into the atmosphere. That’s an impressive contribution from organisms that can’t be seen with the naked eye. </p>
<p>Using sophisticated techniques and equipment, I am sorting the phytoplankton communities in the Agulhas system based on how they fluoresce – that is, light up. This helps me to organise them by different species that perform different functions. I’m also investigating how two size classes of diverse phytoplankton communities take up various species of nitrogen within the nutrient starved waters of the Agulhas marine system. </p>
<p>I focus on two nitrogen species; only one of them, nitrate, is responsible for drawing carbon down from the atmosphere. Additionally, I investigate the productivity of the ocean. This involves looking at which parts of this ocean basin have the most phytoplankton and where nutrient uptake is most efficient. I closely study and calculate the uptake rates of the nitrogen species and carbon export within this ocean basin.</p>
<p>This is one of the very few studies looking closely at marine biogeochemistry of the Agulhas System Climate Array system. Marine biogeochemistry is an interdisciplinary field of oceanography that deals with the relationships between marine chemistry, marine biological and geochemical processes with the aim to uncover the interactions and responses between ocean chemistry, marine biology and global change.</p>
<h2>Seeking answers</h2>
<p>My research will ultimately allow us to understand how the various phytoplankton communities in the Agulhas marine system take up different nitrogen species. This is directly related to the amount of carbon dioxide that can be pumped into the ocean’s interior. </p>
<p>Calculating the rates will ultimately reveal the rate at which carbon is being exported through the “biological pump” process to the deep ocean. When we know this, we’ll have a better understanding of just how productive the system is in terms of absorbing and circulating carbon dioxide. This will ultimately help us understand how the planet cools itself in a warming world.</p><img src="https://counter.theconversation.com/content/114844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kolisa Yola Sinyanya works for the University of Cape Town (UCT). She receives funding from UCT and Dr Sarah Fawcett, and is affiliated with Dr Sarah Fawcett. </span></em></p>Phytoplankton are tiny, but they do important work.Kolisa Yola Sinyanya, PhD Candidate, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/931142018-04-19T10:50:41Z2018-04-19T10:50:41ZClimate change could alter ocean food chains, leading to far fewer fish in the sea<figure><img src="https://images.theconversation.com/files/214794/original/file-20180413-127631-x3zcer.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sustained ocean warming could greatly reduce catches of fish like these herring photographed off Norway.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/2mhTmW">Jacob Botter</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Climate change is rapidly warming the Earth and altering ecosystems on land and at sea that produce our food. In the oceans, most added heat from climate warming is still near the surface and will take centuries to work down into deeper waters. But as this happens, it will change ocean circulation patterns and make ocean food chains less productive.</p>
<p>In a recent <a href="http://dx.doi.org/10.1126/science.aao6379">study</a>, I worked with colleagues from five universities and laboratories to examine how climate warming out to the year 2300 could affect marine ecosystems and global fisheries. We wanted to know how sustained warming would change the supply of key nutrients that support tiny plankton, which in turn are food for fish.</p>
<p>We found that warming on this scale would alter key factors that drive marine ecosystems, including winds, water temperatures, sea ice cover and ocean circulation. The resulting disruptions would transfer nutrients from surface waters down into the deep ocean, leaving less at the surface to support plankton growth. </p>
<p>As marine ecosystems become increasingly nutrient-starved over time, we estimate global fish catch could be reduced 20 percent by 2300, and by nearly 60 percent across the North Atlantic. This would be an enormous reduction in a key food source for millions of people.</p>
<h2>Ocean food production and the biological pump</h2>
<p>Marine food production starts when the sun shines on the ocean’s surface. Single-celled, mostly microscopic organisms called phytoplankton – the plants of the oceans – use sunlight to photosynthesize and grow in a process called net primary production. They can only do this in the sunlit surface layer of the ocean, down to about 100 meters (330 feet). But they also need nutrients to grow, particularly nitrogen and phosphorus, which can be scarce in surface waters.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/214795/original/file-20180413-584-xi1fi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Phytoplankton, the plants of the ocean.</span>
<span class="attribution"><a class="source" href="http://www.photolib.noaa.gov/bigs/fish1879.jpg">NOAA</a></span>
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</figure>
<p>Phytoplankton are consumed by zooplankton (tiny animals), which in turn provide food for small fish, and so on all the way up the food chain to top predators like dolphins and sharks. Unconsumed phytoplankton and other organic matter, such as dead zooplankton and fish, decompose in surface waters, releasing nutrients that support new phytoplankton growth. </p>
<p>Some of this material sinks down into the deeper ocean, providing food for deep sea ecosystems. Carbon, nitrogen, phosphorus and other nutrients in this sinking organic matter ultimately are decomposed and released at depth. </p>
<p>This process, which is known as the <a href="http://earthguide.ucsd.edu/virtualmuseum/climatechange1/06_2.shtml">biological pump</a>, continually removes nutrients from surface waters and transfers them to the deeper ocean. Under normal conditions, winds and currents cause mixing that eventually brings nutrients back up to the sunlit surface waters. If this did not happen, the phytoplankton eventually would completely run out of nutrients, which would affect the entire ocean food chain.</p>
<h2>Sea ice, winds and nutrient upwelling</h2>
<p>Nutrients that sink to the deep ocean eventually return to the surface mainly in the Southern Ocean around Antarctica. North of Antarctica, strong westerly winds push surface waters away from Antarctica. As this happens, deep ocean waters that are rich in nutrients rise up to the surface all around Antarctica, replacing the waters that are being pushed away. The zone where this <a href="https://oceanservice.noaa.gov/facts/upwelling.html">upwelling</a> occurs is called the Antarctic Divergence. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=235&fit=crop&dpr=1 600w, https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=235&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=235&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=295&fit=crop&dpr=1 754w, https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=295&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/212747/original/file-20180330-189827-105uft5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=295&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When winds displace surface ocean waters, nutrient-rich colder waters well up from below.</span>
<span class="attribution"><a class="source" href="https://oceanservice.noaa.gov/facts/upwelling.html">NOAA</a></span>
</figcaption>
</figure>
<p>Today there isn’t a lot of phytoplankton growth in the Southern Ocean. Heavy sea ice cover prevents much sunlight from reaching the oceans. Concentrations of iron (another key nutrient) in the water are low, and cold water temperatures limit plankton growth rates. As a result, most nitrogen and phosphorus that upwells in this area flows northwards in surface waters. Eventually, when these nutrients reach warmer waters throughout the lower latitudes, they support plankton growth over most of the Pacific, Indian and Atlantic oceans.</p>
<h2>Trapping nutrients in the deep ocean</h2>
<p>Our <a href="http://dx.doi.org/10.1126/science.aao6379">study</a> demonstrated that sustained, multicentury global warming could short-circuit this process, leaving all ocean areas to the north of this Antarctic zone increasingly starved for nitrogen and phosphorus. </p>
<p>We used a climate model simulation that assumed nations continued to use fossil fuels until global reserves were exhausted. This climate path would raise mean surface air temperature by 9.6 degrees Celsius (17.2 degrees Fahrenheit) by 2300 – nearly 10 times the warming beyond pre-industrial levels recorded up to the present. Scientists already know that the poles are <a href="https://www.nasa.gov/topics/earth/features/warmingpoles.html">warming faster than the rest of the planet</a>, and in this scenario that pattern continues. Eventually the oceans would no longer freeze over near the poles, even in winter. </p>
<p>Warmer ocean waters without sea ice, aided by shifts in winds that are also driven by strong climate warming, would greatly improve growth conditions around Antarctica for phytoplankton. This increased growth would trap nutrients that well up near Antarctica, preventing them from flowing northwards and supporting low-latitude ecosystems worldwide. </p>
<p>In our simulation, these trapped nutrients eventually mix back to the deep ocean and accumulate there. Nitrogen and phosphorus concentrations in the upper 1,000 meters (3,300 feet) of the ocean steadily decrease. In the deep ocean, below 2,000 meters, they steadily increase. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=771&fit=crop&dpr=1 600w, https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=771&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=771&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=969&fit=crop&dpr=1 754w, https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=969&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/214852/original/file-20180414-543-ewku7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=969&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Large, brilliant clouds of blue in the dark waters of the South Atlantic are phytoplankton blooms. Nutrients drifting north from Antarctica fuel these blooms, which provide food for larger plankton and fish.</span>
<span class="attribution"><a class="source" href="https://visibleearth.nasa.gov/view.php?id=69773">Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC</a></span>
</figcaption>
</figure>
<h2>Far fewer fish</h2>
<p>As marine ecosystems become increasingly nutrient-starved, phytoplankton growth and net primary production throughout most of the world’s oceans would decline. We estimate that as these impacts ripple up the food chain, global fish catches could be reduced 20 percent by 2300, with decreases of more than 50 percent across the North Atlantic and several other regions. Moreover, at the end of our simulation net transfer of nutrients to the deep ocean was still taking place, which suggests that ecosystem productivity and potential fisheries catch would decline even further beyond 2300. </p>
<p>Eventually, after more than a thousand years, most of the carbon dioxide that human activities have added to the atmosphere will be absorbed by the oceans, and the Earth’s climate will cool back down. Sea ice will return to polar oceans, suppressing phytoplankton growth around Antarctica and allowing more upwelled nutrients to flow north once again to lower latitudes. But even then, it will take centuries more for ocean circulation to fully replenish nutrients in the upper ocean. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/H7sACT0Dx0Q?wmode=transparent&start=30" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Phytoplankton are critical to life on Earth. Climate change is interfering with ocean mixing processes that promote phytoplankton growth.</span></figcaption>
</figure>
<p>Ocean resources are already stressed today. About 90 percent of the world’s marine fisheries are <a href="http://www.fao.org/3/a-i5555e.pdf">fully fished or overfished</a>. World population is <a href="http://www.un.org/en/development/desa/news/population/2015-report.html">projected to increase</a> from 7.3 billion in 2015 to 11 billion in 2100. The impacts that we found in our study would have serious implications for global food security. <a href="https://theconversation.com/how-a-tiny-portion-of-the-worlds-oceans-could-help-meet-global-seafood-demand-82680">Expanding aquaculture</a>, or even more drastic steps such as directly <a href="https://web.whoi.edu/ocb-fert/science-background/">fertilizing the oceans</a> to spur plankton growth, would not even come close to making up for the loss of nutrients to the deep ocean driven by sustained global warming.</p>
<p>Our simulation was based on a strong climate warming scenario. <a href="http://dx.doi.org/10.1126/science.aat0795">More research</a> is needed to explore just how warm the climate has to get to melt sea ice and initiate Southern Ocean nutrient trapping. But clearly this is a tipping point that we don’t want to cross.</p><img src="https://counter.theconversation.com/content/93114/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jefferson Keith Moore receives funding from the National Science Foundation and the U.S. Department of Energy.</span></em></p>Fish are a key food source for millions of people worldwide. But a recent study finds long-term warming over the next 200 years could starve tiny plankton, with impacts that would ripple up food chains.Jefferson Keith Moore, Professor of Earth System Science, University of California, IrvineLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/886372017-12-06T23:11:28Z2017-12-06T23:11:28ZDrought on the Murray River harms ocean life too<figure><img src="https://images.theconversation.com/files/197954/original/file-20171206-896-z9mjw2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The mouth of the Murray River delivers vital nutrients to marine life in the ocean beyond.</span> <span class="attribution"><span class="source">SA Water</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Drought in the Murray River doesn’t just affect the river itself – it also affects the ecosystems that live in the ocean beyond.</p>
<p>In a study <a href="http://www.publish.csiro.au/MF/justaccepted/MF17226">published in Marine and Freshwater Research today</a>, we found that the very low flows in the river over the past decade reduced the abundance of microscopic marine plants called phytoplankton, which are ultimately the base of all marine food webs.</p>
<p>This shows that the health of the Murray River has a much bigger influence on the marine environment than we previously realised. With climate change poised to make droughts more frequent and severe in the river, it will be crucial to monitor the health not just of freshwater species, but of the local marine ones too. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-the-murray-darling-basin-plan-broken-81613">Is the Murray-Darling Basin Plan broken?</a>
</strong>
</em>
</p>
<hr>
<p>Phytoplankton depend on nutrients, which are often delivered to the ocean by rivers. In turn, these tiny plants are a source of food for almost all marine ecosystems. Worldwide, they are responsible for <a href="http://science.sciencemag.org/content/281/5374/237">half the production of organic matter on the planet</a>.</p>
<p>In South Australia, a dry period dubbed the Millennium Drought (2001 to 2010) and overallocation of water resources (primarily for agriculture) meant that very little water was delivered from the Murray Mouth to the coastal ocean. Between 2007 and 2010, <a href="https://doi.org/10.1007/s11269-012-0113-2">no water was discharged at all</a>. The water in the river’s lower reaches became much saltier and cloudier.</p>
<p>We used historical flow records and <a href="https://oceancolor.gsfc.nasa.gov/">satellite imagery</a>, taken between early 2002 and late 2016, to figure out how much phytoplankton and other organic matter were in the coastal ocean each month. We broke up the area into incremental zones, venturing up to 130km from the river mouth.</p>
<p>We found that during and after high-flow events, Murray River discharge resulted in a huge increase in phytoplankton concentrations – as far as 60km beyond the river’s mouth. Surprisingly, before our research it wasn’t known that the river played such an important role in stimulating phytoplankton growth over such a large area.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/197717/original/file-20171205-23047-1fz8pbt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&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 mouth of the Murray River, where sometimes no water flows into the ocean at all.</span>
<span class="attribution"><span class="source">CSIRO/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Armed with an understanding of how river flows influenced phytoplankton growth, we used historic flow records to estimate phytoplankton concentrations back to 1962. Our results showed that large flows used to occur more often and in greater volumes, and consequently that phytoplankton populations would have gone through more frequent and larger booms.</p>
<p>This in turn would have benefited all of the species that ultimately depend on phytoplankton for food, either directly or indirectly. This food web encompasses almost the whole marine ecosystem.</p>
<h2>The past affects the future</h2>
<p>Water resource management has greatly altered the volume and timing of freshwater discharges from the Murray. The ocean beyond the Murray mouth now receives small and infrequent deliveries of freshwater.</p>
<p>Rainfall and streamflow are <a href="https://www.nature.com/articles/nature04312">decreasing</a> in this already variable region, while <a href="https://www.environment.sa.gov.au/Science/Science_research/climate-change/climate-change-initiatives-in-south-australia/sa-climate-change-strategy">temperatures are rising</a>. This means that South Australia is likely to experience more severe and more frequent droughts, which will cause flows from the Murray mouth to decline still further, ultimately reducing phytoplankton abundance.</p>
<p><a href="http://onlinelibrary.wiley.com/doi/10.1029/2004GL021852/abstract">Previous research</a> had already established the links between river outflows, phytoplankton and health of marine environments and species. But as far as we can tell, no other research has looked at exactly how extended periods of no or low river outflows affect marine ecosystems. This makes it difficult to predict how these systems will respond to climate change.</p>
<p>We believe that reduced Murray River outflows and reduced phytoplankton concentrations would likely have also placed strain on local mulloway fish and Goolwa cockle populations. Juvenile mulloway use river outflows as habitat and environmental cues, and cockles feed on organic material in the water.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tax-returns-for-water-satellite-audited-statements-can-save-the-murray-darling-81833">'Tax returns for water': satellite-audited statements can save the Murray-Darling</a>
</strong>
</em>
</p>
<hr>
<p>This is why it is so important that the management of the Murray River doesn’t just stop at the river’s mouth, but continues into the ocean beyond. <a href="https://www.mdba.gov.au/basin-plan">Current plans</a> are focused on restoring flows to support the riparian and wetland ecosystems of the Murray as well as the Lower Lakes and Coorong.</p>
<p>But there has been little recognition of the role of river outflows on the marine environment – let alone in management. Although we might not always think about it, the marine environment is really the end of the river system, and part of a larger global cycle. It would therefore be beneficial if plans extend to monitor the marine ecosystem’s response, both at broad and fine scales, to varying flow events.</p>
<p>It would seem the time is past ripe to call for greater research and consideration on this matter, so that we don’t do further damage to what is actually still a part of the Murray River system, and can improve measures to protect the marine environment.</p><img src="https://counter.theconversation.com/content/88637/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Low flows in the Murray River in recent years have harmed tiny marine plants called phytoplankton, with consequences for local marine species and management.Hannah Auricht, PhD candidate, University of AdelaideKenneth Clarke, Researcher, School of Biological Sciences, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/694972017-07-18T14:43:26Z2017-07-18T14:43:26ZWhy deeper insights into the Agulhas Current can shed light on climate patterns<figure><img src="https://images.theconversation.com/files/178359/original/file-20170716-30889-1gazz4s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/pamilne/6127056073/">Flickr/Philip Milne</a></span></figcaption></figure><p><em>South Africa has one of the fastest and strongest flowing currents in the world running along its east coast: the Agulhas Current. It influences local as well as global rainfall and <a href="https://www.nature.com/nature/journal/v472/n7344/abs/nature09983.html">climate</a>. Katherine Hutchinson explains why it’s important to monitor a current that plays a significant role in the global ocean conveyor belt.</em></p>
<p><strong>What is the impact of the Agulhas Current on the local climate and why does it matter in the global context?</strong></p>
<p>The Agulhas Current transports warm tropical Indian Ocean water southwards along the South African coast. It modulates the rainfall along the east coast and interior regions of South Africa by providing the latent heat of evaporation needed for onshore wind systems to pick up moisture and carry it inland. </p>
<p>The current itself also sets the backdrop for local ecosystems which contribute to South African fisheries. Friction between the current and the continental shelf edge drives upwelling of nutrient rich bottom water. This in turn promotes high levels of phytoplankton – the grass of the ocean which sustains the aquatic food web. </p>
<p>The Agulhas Current also plays a critical role in global ocean circulation which is why it’s considered important for climatic conditions across the world.</p>
<p>This is due to a process known as the <a href="http://public.lanl.gov/wilbert/Research/AgulhasLeakage.html">Agulhas Leakage</a>. The current flows along the east coast of South Africa and then turns back on itself flowing into the Indian Ocean. But during this process (known as a retroflection), large pockets of warm, salty, Indian Ocean water are pinched off from the current. They form ring-like structures called Agulhas Rings or eddies which are massive spinning vortices. These eddies slowly head north-westwards, crossing the South Atlantic Ocean and eventually feed into the Gulf Stream which flows along the east coast of North America. </p>
<p>The Gulf Stream helps modulate the climate conditions of North America and Western Europe. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178103/original/file-20170713-9618-v1v0f0.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">A map of the Agulhas Current System.</span>
<span class="attribution"><span class="source">provided by author</span></span>
</figcaption>
</figure>
<p><strong>How do we know this?</strong></p>
<p>Oceanographers understand currents by measuring the changes in the ocean. But the challenge up until recently had been that the data collected on the Agulhas System only explained the current’s behaviour at a certain point in time. </p>
<p>As a result, many oceanographers have turned to computer models that simulate how ocean currents respond to other factors – like winds – which are measured by satellites. These models are not perfect, but can be very useful in providing insight into connections between different factors affecting the ocean.</p>
<p>The complex nature of the Agulhas Current has made it very difficult to simulate using ocean models. Until 2010 oceanographers were only able to observe the Agulhas Current with snapshots they got by deploying instruments during research cruises.</p>
<p>But scientific developments, combined with international collaboration, have allowed South Africa to place two long term monitoring lines across areas of the ocean where it’s believed critical exchanges of heat and salt are taking place. Heat and salt are essential parameters as they determine the buoyancy of a water mass, its tendency to sink or float. Buoyancy differences and wind forcing are the two mechanisms that drive ocean circulation. </p>
<p>To measure the oceans response to climatic changes (alterations in heat and salt fluxes and shifts in wind patterns), continuous monitoring is needed. These monitoring lines are made up of instruments placed throughout the water column. They measure current speed, direction and temperature at extremely high temporal resolutions. </p>
<p>The first array ran from 2010 to 2013 <a href="http://act.rsmas.miami.edu/">(the Agulhas Current Time-series) Experiment)</a>. This consisted of moorings placed across the Agulhas Current just off the coast of Port Elizabeth. In 2015 oceanographers replaced it with the <a href="http://asca.dirisa.org/">Agulhas System Climate Array</a>. These moorings are currently measuring the evolution of the Agulhas Current with time, providing scientists with vital information on the current’s behaviour. </p>
<p><strong>Where are the gaps?</strong></p>
<p>The ASCA array sheds a great deal of light on the behaviour of the Agulhas Current and the local implications for South Africa. But it doesn’t provide information on the amount of warm Agulhas water being leaked into the South Atlantic. This leakage is a critical link in the global ocean conveyor belt and so understanding how it is changing over time is essential in preparing for the consequences of climate change. </p>
<p>Another project was initiated in 2013 to measure the exchange of water from the Indian Ocean into the South Atlantic, the South Atlantic MOC Basin-wide Array (SAMBA). South Africa, in collaboration with France and Brazil, placed a series of instruments to capture the “corridor” of Agulhas Rings that cross the Atlantic. The aim is to monitor long term changes in inter-ocean exchange at the east and west borders of the <a href="http://onlinelibrary.wiley.com/doi/10.1002/2014EO060001/full">South Atlantic</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=263&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=263&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=263&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=331&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=331&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178240/original/file-20170714-14315-c05fln.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=331&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Depictions of the SAMBA and ASCA arrays.</span>
<span class="attribution"><span class="source">provided by author</span></span>
</figcaption>
</figure>
<p>Brazil, the United States and Argentina have deployed similar moorings on the western portion of the basin contributing to the end goal – to create a basin-wide array to bridge the entire South Atlantic. </p>
<p><strong>What do we know so far?</strong></p>
<p>South Africa is located at a major crossroad of ocean-basin exchange between the Indian and Atlantic Oceans. Several <a href="http://onlinelibrary.wiley.com/doi/10.1029/2008GL036614/full">modelling studies</a> have tried to simulate how these exchanges will alter with climate change under varying scenarios. But they have often <a href="http://journals.ametsoc.org/doi/abs/10.1175/JPO-D-13-093.1">produced</a> <a href="https://www.nature.com/nature/journal/v462/n7272/abs/nature08519.html">conflicting and inconclusive findings</a>. </p>
<p>Oceanographers previously believed that the Agulhas Current had been strengthening over time due to an increase in the Southern Hemisphere winds. But the array showed that it has been <a href="https://www.nature.com/nature/journal/v540/n7634/abs/nature19853.html">broadening</a> and not strengthening. The effects of this broadening are currently being investigated, but one outcome is that a wider current allows for a greater exchange of water between the inshore and offshore areas meaning that pollutants will more easily be shifted out to sea. </p>
<p>It’s crucial that in-situ monitoring of the Agulhas Current system continues. This kind of data will allow scientists to detect changes in the current over time. It will also help oceanographers improve their models and help them understand how variations in the current affect local and global ocean circulation and climate.</p><img src="https://counter.theconversation.com/content/69497/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katherine Hutchinson receives funding from the South African National Research Foundation under the Professional Development Programme hosted by the South African Environmental Observations Network. </span></em></p>The Agulhas Current plays a critical role in global ocean circulation that influences climatic conditions across the world.Katherine Hutchinson, PhD Candidate, South African Environmental Observations Network, and Department of Oceanography UCT, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/793532017-06-15T20:06:03Z2017-06-15T20:06:03ZVolcanoes under the ice: melting Antarctic ice could fight climate change<figure><img src="https://images.theconversation.com/files/173930/original/file-20170615-24988-wlh6r4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Furious winds keep the McMurdo Dry Valleys in Anarctica free of snow and ice. Calcites found in the valleys have revealed the secrets of ancient subglacial volcanoes. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/24354425@N03/15974778779/">Stuart Rankin/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Iron is not commonly famous for its role as a micronutrient for tiny organisms dwelling in the cold waters of polar oceans. But iron feeds plankton, which in turn hold carbon dioxide in their bodies. When they die, the creatures sink to the bottom of the sea, safely storing that carbon.</p>
<p>How exactly the iron gets to the Southern Ocean is hotly debated, but we do know that during the last ice age huge amounts of carbon were stored at the <a href="https://phys.org/news/2016-02-southern-ocean-carbon-dioxide-mystery.html">bottom of the Southern Ocean</a>. Understanding how carbon comes to be stored in the depth of the oceans could help abate CO<sub>2</sub> in the atmosphere, and Antarctica has a powerful role.</p>
<p>Icebergs and atmospheric dust are believed to have been the major sources of this micronutrient in the past. However, in research published in <a href="https://www.nature.com/articles/ncomms15425.epdf?author_access_token=q_njgY8kpm9uOzHBOzIjStRgN0jAjWel9jnR3ZoTv0NDijqdEtnSa_-cRAA3I9D3guB7Wt4waDbHdtXGPg1cnTcvt5ruEU3njHse_z94Ybx16w8amxBJz7ivo8fvlEG_">Nature Communications</a>, my colleagues and I examined calcite crusts from Antarctica, and found that volcanoes under its glaciers were vital in delivering iron to the ocean during the last ice age. </p>
<p>Today, glacial meltwaters from Greenland and the Antarctic peninsula supply iron both in solution and as tiny particles (less than 0.0001mm in diameter), which are readily consumed by plankton. Where glaciers meet bedrock, minute organisms can live in pockets of relatively warm water. They are able to extract “food” from the rock, and in doing so release iron, which then can be carried by underwater rivers to the sea. </p>
<p>Volcanic eruptions under the ice can create underwater subglacial lakes, which, at times, discharge downstream large masses of water that travel to the ice margin and beyond, carrying with them iron in particle and in solution.</p>
<p>The role of melting ice in climate change is as yet poorly understood. It’s particularly pertinent as scientists predict the imminent collapse of part of the <a href="https://www.theguardian.com/environment/climate-consensus-97-per-cent/2017/jun/12/the-larsen-c-ice-shelf-collapse-hammers-home-the-reality-of-climate-change">Larsen C ice shelf</a>.</p>
<p>Researchers are also investigating how to <a href="http://www.gc.noaa.gov/documents/2010_climate_fert_rept_Congress_final.pdf">reproduce natural iron fertilisation in the Southern Ocean</a> and induce algal blooms. By interrogating the volcanic archive, we learn more about the effect that iron fertilisation from meltwater has on global temperatures. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=557&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=557&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=557&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=700&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=700&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=700&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 polished wafer of the subglacial calcites. The translucent, crystalline layers formed while in pockets of water, providing nourishment to microbes. The opaque calcite with rock fragments documents a period when waters discharged from a subglacial lake formed by a volcanic eruption, carrying away both iron in solution and particles of iron.</span>
<span class="attribution"><span class="source">Supplied</span></span>
</figcaption>
</figure>
<h2>The Last Glacial Maximum</h2>
<p>During the <a href="https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-4-1-2.html">Last Glacial Maximum</a>, a period 27,000 to 17,000 years ago when glaciers were at their greatest extent worldwide, the amount of CO<sub>2</sub> in the atmosphere was lowered to 180 parts per million (ppm) relative to pre-industrial levels (280 ppm). </p>
<p>Today we are at <a href="https://theconversation.com/february-carbon-dioxide-levels-average-400ppm-for-first-time-38417">400 ppm</a> and, if current warming trends continue, a <a href="https://theconversation.com/teetering-on-a-tipping-point-dangerous-climate-change-in-the-arctic-5156">point of no return</a> will be reached. The global temperature system will return to the age of the dinosaurs, when there was little difference in temperature from the equator to the poles.</p>
<p>If we are interested in providing a habitable planet for our descendants, we need to mitigate the quantity of carbon in the atmosphere. Blooms of plankton in the Southern Ocean boosted by iron fertilisation were one important ingredient in lowering CO<sub>2</sub> in the Last Glacial Maximum, and they could help us today.</p>
<p>The Last Glacial Maximum had winds that spread dust from deserts and icebergs carrying small particles into the Southern Ocean, providing the necessary iron for algal blooms. These extreme conditions don’t exist today. </p>
<h2>Hidden volcanoes</h2>
<p>Neither dust nor icebergs alone, however, explain bursts of productivity recorded in ocean sediments in the Last Glacial Maximum. There was another ingredient, only discovered in rare archives of subglacial processes that could be precisely dated to the Last Glacial Maximum.</p>
<p>Loss of ice in Antartica’s <a href="http://icestories.exploratorium.edu/dispatches/big-ideas/dry-valleys/index.html">Dry Valleys</a> uncovered rusty-red crusts of calcite plastered on glacially polished rocks. The calcites have tiny layers that can be precisely dated by radiometric techniques.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=926&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=926&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=926&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1164&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1164&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1164&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 piece of subglacial calcite coating pebbles. This suggests that the current transporting the pebbles was quite fast, like a mountain stream. The pebbles were deposited at the same time as the opaque layer in the calcite formed.</span>
<span class="attribution"><span class="source">Supplied</span></span>
</figcaption>
</figure>
<p>Each layer preserves in its chemistry and DNA a record of processes that contributed to delivering iron to the Southern Ocean. For example, fluorine-rich spherules indicate that underwater vents created by volcanic activity injected a rich mixture of minerals into the subglacial environment. This was confirmed by DNA data, revealing a thriving community of <a href="https://serc.carleton.edu/microbelife/extreme/extremeheat/index.html">thermophiles</a> – microorganisms that live in very hot water only.</p>
<p>Then, it became plausible to hypothesise that volcanic eruptions occurred subglacially and formed a subglacial lake, whose waters ran into an interconnected system of channels, ultimately reaching the ice margin. Meltwater drained iron from pockets created where ice met bedrock, which then reached the ocean – thus inducing algal blooms. </p>
<p>We dated this drainage activity to a period when dust flux does not match ocean productivity. Thus, our study indicates that volcanoes in Antarctica had a role in delivering iron to the Southern Ocean, and potentially contributed to lowering CO<sub>2</sub> levels in the atmosphere.</p>
<p>Our research helps explain how volcanoes act on climate change. But it also uncovers more about iron fertilisation as a possible way to mitigate global warming.</p><img src="https://counter.theconversation.com/content/79353/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Silvia Frisia receives funding from ARC.</span></em></p>Melting ice from Antartica could feed vast plankton blooms, trapping carbon in the ocean. To understand this complex mechanism, researchers looked at volcanoes deep under glaciers.Silvia Frisia, Associate Professor, School of Environmental and Life Sciences , University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/726132017-02-22T14:34:03Z2017-02-22T14:34:03ZYoung African penguins are dying because they can’t find the fish they need<figure><img src="https://images.theconversation.com/files/157521/original/image-20170220-15931-1s03t3b.jpg?ixlib=rb-1.1.0&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>When young African penguins leave their nests for the first time they do so alone, without any guidance <a href="http://www.penguins.cl/african-penguins.htm">from their parents</a>. They need to use their instinct to follow cues in their environment to find food and stay alive in their first months at sea. Hard as that may have been in the past, today climate change and high fishing pressure have made it even more difficult.</p>
<p>For penguins in South Africa and Namibia, abundant supplies of their favoured prey, such as sardine and anchovy, are no longer where the penguins expect to find them. This causes the young birds to fall into what is known as an ecological trap. This is when they follow the usual cues to feeding grounds only to find that the sources of food in these places is no longer available. This can be due to changes in stocks of particular foods due to over-fishing or <a href="https://www.carbonbrief.org/climate-change-fishing-lay-ecological-trap-african-penguins">underlying environmental change</a></p>
<p>African penguins are listed as endangered by the <a href="https://www.iucn.org/">International Union for Conservation of Nature</a>, as numbers along their entire range in South Africa and Namibia have dramatically decreased in the last century and trends currently don’t show any <a href="http://www.iucnredlist.org/details/22697810/0">sign of reversing</a>. In the last 50 years, the population has dropped by 80% and there are only about 23 000 breeding pairs in the wild. </p>
<p>In our <a href="http://www.cell.com/current-biology/fulltext/S0960-9822(16)31536-6">new study,</a> we followed 54 <a href="http://penguins.neaq.org/2010/06/whats-happening-first-molt.html">juvenile penguins</a> – penguins who have lost their down feathers and are now waterproof and ready to go to sea – on their initial journey along the southern African coast using satellite transmitters. </p>
<h2>Dwindling fish stocks</h2>
<p>The birds moved to areas of the ocean where sea temperatures are low and productivity – in the form of the <a href="http://oceanservice.noaa.gov/facts/phyto.html">phytoplankton</a> microscopic food that is the base of many aquatic food webs – is high. To do so, they travelled large distances to areas such as St. Helena Bay along the West Coast of South Africa and Swakopmund in central Namibia. Both are historically known for their high fish abundance.</p>
<p>But large fish stocks no longer exist <a href="https://academic.oup.com/icesjms/article/65/9/1676/632495/Has-the-fishery-contributed-to-a-major-shift-in">in these areas</a>. This is because of the combined effects of the changing climate and fishing pressure. Since the lower levels of the ecosystem have not been affected in the same way, the signals that the penguins would have always used to locate their prey are still intact. </p>
<p>For example the phytoplankton is still there and is still preyed upon by <a href="https://www.whoi.edu/main/topic/jellyfish-zooplankton">zooplankton</a>, microscopic animals drifting in the ocean. But today, the fish that would normally co-occur with their planktonic prey are scarce or absent. </p>
<p>Juvenile penguins are “tricked” into selecting the now poor habitat and fall into this large-scale ecological trap. This previously unnoticed ecosystem-wide phenomena explains the low survival chances of this endangered species, especially during its first year at sea. It contributes to the dramatic decline of <a href="http://onlinelibrary.wiley.com/doi/10.1111/ibi.12189/abstract">the penguin population</a>.</p>
<p>Modelling exercises in the current study showed that with sufficient food in these areas, the African penguin population on the West Coast of South Africa would be twice the size it is now. There would be around 5,000 pairs at Dassen and Robben Islands, instead of only around 2,500. Only juvenile penguins from the Eastern Cape colonies, located in Algoa Bay, foraged in an area which provides sufficient food, the Agulhas Bank. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157522/original/image-20170220-15908-1nb68c2.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">In the last 50 years, the Africa penguin population has dropped significantly.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Escaping the trap?</h2>
<p>Several conservation measures are being taken to halt the decline of the African penguin and a few could help get the penguins out of this ecological trap. Efforts to hand-raise chicks and create <a href="https://medium.com/this-is-an-experiment/establishing-a-new-african-penguin-colony-d235ff9c4ea7#.utmopmtd3">new penguin colonies</a> may help bolster the population and build resilience against future change. <a href="https://sanccob.co.za">The Southern African Foundation for the Conservation of Coastal Birds</a>, South Africa’s largest rehabilitation centre, hand-rears several hundred chicks each year. This happens after they are abandoned in the colonies because their parents get oiled or injured, or simply cannot find enough food to raise them during the breeding season.</p>
<p>Once these birds reach fledgling age, they are released back into the wild. Fourteen of the penguins in this study were hand-reared and the results show that these chicks behave in the same way as counterparts raised by their parents. Unfortunately, these penguins also travel into areas with low food availability.</p>
<p>The chicks raised at the centre behave naturally once back in the wild and could be used as part of efforts <a href="https://experiment.com/projects/establishing-a-new-african-penguin-colony-predator-monitoring">to create new penguin colonies</a> by releasing them at designated areas where they could found new colonies in closer proximity to the available food. </p>
<p>But a great deal more needs to be done to address the problem of the ecological trap. The study shows that large scale conservation measures – such as reduced fish quota or suspension of the fisheries once the fish population falls below critical ecological thresholds – are urgently needed to protect the endangered African penguin and other seabirds in the Benguela Current, a highly productive cold water system along the west coast of Southern Africa. These measures must go hand-in-hand with conservation initiatives that are in place already.</p>
<p>The ecological trap for African penguins was discovered by tracking juveniles. This is an age group about which very little is known in many seabird species. It highlights the importance of further studies on the survival strategies in the first year of particular seabirds’ life to understand the dynamics of species across their range.</p><img src="https://counter.theconversation.com/content/72613/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katrin Ludynia receives funding from AZA SAFE and has previously received funding through NRF, DAAD (German Exchange Programme), Konrad-Adenauer-Foundation and German governmental grants. She is affiliated with the Atlantic and the African Seabird Groups. </span></em></p><p class="fine-print"><em><span>Richard Sherley receives funding from AZA SAFE, the Leiden Conservation Foundation, National Research Foundation (South Africa) and has previously received funding from the Bristol Zoological Society and UK and South African government grants. He is affiliated with the Seabird Group. </span></em></p>Young African penguins are following the usual cues to feeding grounds only to find that the sources of food in these places is no longer available. This is devastating for their numbers.Katrin Ludynia, Honorary Research Associate and Research Manager at SANCCOB, University of Cape TownRichard Sherley, Research Fellow, Bristol Zoological Society and University of Exeter, University of ExeterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/691542016-11-23T04:47:51Z2016-11-23T04:47:51ZCould ‘whale poo diplomacy’ help bring an end to whaling?<figure><img src="https://images.theconversation.com/files/147117/original/image-20161123-19726-p1i2ls.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The idea is to come up with better alternatives to this.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File%3AJapan_Factory_Ship_Nisshin_Maru_Whaling_Mother_and_Calf.jpg">Australian Customs and Border Protection Service</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Japan’s fleet has <a href="http://www.news.com.au/world/breaking-news/japan-kicks-off-whaling-season/news-story/39637fc0e6776a370639fa5926d13b7b">left port</a> for another season of “scientific” research whaling in the Southern Ocean.</p>
<p>Like <a href="https://theconversation.com/japans-whaling-fleet-sets-sail-again-and-theres-not-much-that-can-stop-it-51556">last year</a>, there is little that anyone can do to legally rescind Japan’s <a href="https://theconversation.com/the-new-international-whaling-resolution-will-do-little-to-stop-japan-killing-whales-67854">self-issued lethal research permit</a> – a fact that has led to calls for <a href="https://theconversation.com/with-a-less-confrontational-approach-to-whaling-more-whales-could-be-saved-68064">more pragmatism and less confrontation</a> in efforts to conserve whales. </p>
<p>Such avenues include greater collaboration between the <a href="https://iwc.int/home">International Whaling Commission (IWC)</a> and other organisations, and a renewed emphasis on marine ecosystem research in the Southern Ocean. </p>
<h2>How whale poo can help</h2>
<p>While Japan’s new whaling program <a href="https://iwc.int/day-four-special-permit-whaling">dominated the IWC’s summit last month</a>, a Chilean-sponsored resolution nicknamed the <a href="http://www.greenpeace.org.au/blog/iwc-kicks-off/">“whale poo” resolution</a> was also quietly adopted at the meeting. </p>
<p>More formally known as the <a href="https://archive.iwc.int/pages/view.php?ref=6185&search=%21collection24471&order_by=relevance&sort=DESC&offset=0&archive=0&k=&curpos=15&restypes=">Draft Resolution on Cetaceans and Their Contribution to Ecosystem Functioning</a>, the resolution notes the growing scientific evidence that whale faeces are <a href="https://theconversation.com/bottoms-up-how-whale-poop-helps-feed-the-ocean-27913">a crucial source of micronutrients for plankton</a>.</p>
<p>The resolution will lead to a review of the ecological, environmental, social and economic aspects of whale defecation “as a matter of importance”, while the IWC’s Scientific Committee will review the research and identify any relevant knowledge gaps.</p>
<h2>Why is this important?</h2>
<p>Much of the Southern Ocean is described as high-nutrient, low-chlorophyll (HNLC) waters. This means that the despite high concentrations of important nutrients such as nitrate and phosphate, the <a href="https://theconversation.com/bottoms-up-how-whale-poop-helps-feed-the-ocean-27913">abundance of phytoplankton is very low</a>.</p>
<p>Phytoplankton is the base of the marine food chain, and plays an important role in the global carbon cycle by removing carbon dioxide in the atmosphere through photosynthesis. However, the growth of phytoplankton in large HNLC regions of the Southern Ocean is limited by the availability of a key micronutrient: iron. In essence, the Southern Ocean is anaemic, and whale poo is the remedy.</p>
<p>It works like this. Antarctic krill graze on phytoplankton, taking up the iron. The krill are then consumed by whales, which store some iron for their own use as an oxygen carrier in their blood (as in ours), but also expel large amounts of iron in their faeces.</p>
<p>Adult blue whales, for example, consume about 2 tonnes of krill a day, and the amount of iron in their faeces is <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1467-2979.2010.00356.x/full">more than 10 million times higher than normal seawater</a>.</p>
<p>Conveniently, whale poo is liquid, and is released at the surface where it can act as a fertiliser to promote phytoplankton growth in the ocean’s sunlit top layers. Therefore, whales are part of a positive feedback loop that helps sustain marine food chains.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=327&fit=crop&dpr=1 600w, https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=327&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=327&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=411&fit=crop&dpr=1 754w, https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=411&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/146958/original/image-20161122-24538-1128os4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=411&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 whale poo positive feedback loop.</span>
<span class="attribution"><span class="source">Indi Hodgson-Johnston/University of Tasmania</span></span>
</figcaption>
</figure>
<p>More whales obviously make more whale poo, so it makes sense that more research and protection should be afforded to whales to ensure a <a href="https://theconversation.com/bottoms-up-how-whale-poop-helps-feed-the-ocean-27913">healthier marine ecosystem</a>. </p>
<p><a href="http://www.antarctica.gov.au/magazine/2006-2010/issue-19-2010/science/whale-poo-fertilises-oceans">Scientists collect whale faeces</a> from the surface of the water, making this a great way to do whale research without killing or harming them.</p>
<h2>What about scientific whaling?</h2>
<p>Some have suggested that the legal arguments against scientific whaling are well and truly exhausted, and that <a href="https://theconversation.com/with-a-less-confrontational-approach-to-whaling-more-whales-could-be-saved-68064">controlled commercial whaling could be the next step</a>. Assuming that anti-whaling nations such as Australia would not follow such a pathway, and that hard law options are frustrated, other avenues to end lethal research are needed. </p>
<p>The whale poo resolution also aims to increase the IWC’s existing collaborations with various research organisations. This includes the <a href="https://www.ccamlr.org/">Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR)</a>, of which Japan is a member. CCAMLR made headlines last month when it approved, by consensus, the <a href="https://www.ccamlr.org/en/news/2016/ccamlr-create-worlds-largest-marine-protected-area">world’s largest marine protected area in Antarctica’s Ross Sea</a>.</p>
<p>While the <a href="https://www.ccamlr.org/en/organisation/camlr-convention">CCAMLR Convention</a> states that nothing in it shall derogate from the rights and obligations under the Whaling Convention, the role of whales are important to CCAMLR’s <a href="https://www.ccamlr.org/en/publications/ecosystem-approach">ecosystem approach</a> to conserving marine life in the Southern Ocean. </p>
<p>Japan’s current whaling program has the <a href="http://www.icrwhale.org/NEWREP-AProtocol.html">stated scientific objective</a> of investigating “the structure and dynamics of the Antarctic marine ecosystem through building ecosystem models”. This aligns with both the research needed for CCAMLR’s ecosystem approach and the Australian Antarctic Division’s <a href="http://www.antarctica.gov.au/science/australian-antarctic-science-strategic-plan-201112-202021/theme-3">own research priorities</a>. </p>
<p>With an emphasis on research such as ecosystem modelling, collaborations that include and value Japan’s abundant <em>non-lethal</em> research in the area could help to most of the stated scientific objectives of Japan’s whaling program without harming whales. </p>
<p>Of course, many people contend that the main purpose of Japan’s whaling program is not scientific. But this doesn’t change the fact that the same old battles at sea and in the courts have done little to prevent the taking of whales. The Whaling Convention cannot be changed, and nor can Japan’s interpretation of it. A different tack is clearly needed in both law and diplomacy. </p>
<p>As the new marine protected area shows, Antarctica is a proven platform of peace. Increasing joint scientific research, and riding on the wave of the recent success in the Ross Sea, may provide fresh dialogue with which to resolve the stalemate. What we need is a newly respectful, non-combative discourse with Japan which, whaling aside, is a brilliant contributor to Antarctic science. </p>
<p>Joint Australian and Japanese research in other areas of Southern Ocean and Antarctic science has a long and friendly history. It is upon these longstanding and positive relationships that research addressing relevant objectives should be focused and funded.</p>
<h2>Constructive intervention</h2>
<p>While some, including the <a href="http://greens.org.au/protecting-worlds-whales">Australian Greens</a>, have called for an Australian government vessel to intervene, Japan is whaling in waters that are recognised by most countries as the high seas. </p>
<p>Since the landmark <a href="https://theconversation.com/japan-could-resume-whaling-this-time-with-the-hagues-blessing-31351">2014 International Court of Justice ruling</a>, Japan no longer consents to that court’s jurisdiction on matters of living marine resources. And with little recognition of Australian jurisdiction in the area, and the risk of any intervention being illegal under <a href="http://www.un.org/depts/los/convention_agreements/texts/unclos/part7.htm">laws of the sea</a>, there is little hope for successful international legal action. Sending an Australian ship to intervene or collect evidence would therefore be largely futile. </p>
<p>On the other hand, researching marine ecosystems in the Southern Ocean is difficult and expensive. Instead of sending a customs vessel, Australia should divert its funds and attention to research that will boost our understanding of the Southern Ocean ecosystem and its role in the global carbon cycle.</p>
<p>By increasing knowledge and recognition of whales’ role in the Southern Ocean ecosystem, the resolution offers yet another avenue for developing norms of non-lethal whale research that are recognised as legitimate by all International Whaling Commission members.</p>
<p>Perhaps in one of Australia’s most vexed diplomatic issues with their close ally, whale poo could pave the way to more intensive and thoughtful scientific collaborations, and help deliver a peaceful end to Japanese whaling in the Southern Ocean.</p>
<p><em>The author would like to thank Lavy Ratnarajah, a biogeochemist at the <a href="http://acecrc.org.au/">Antarctic Climate and Ecosystems CRC</a>, for her kind assistance with the scientific aspects of this article. The views expressed are solely those of the author.</em></p><img src="https://counter.theconversation.com/content/69154/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Indi Hodgson-Johnston receives funding from the University of Tasmania. </span></em></p>Japan’s fleet is on its way to the Southern Ocean for more “scientific” whaling. But a new resolution pointing out the importance of whale poo could help remove Japan’s rationale for lethal research.Indi Hodgson-Johnston, Antarctic Law Researcher, PhD Candidate, Institute for Marine and Antarctic Studies and the Antarctic Climate and Ecosystems CRC, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.