tag:theconversation.com,2011:/fr/topics/lakes-5808/articlesLakes – The Conversation2024-03-26T21:00:42Ztag:theconversation.com,2011:article/2254282024-03-26T21:00:42Z2024-03-26T21:00:42ZAnthropocene or not, it is our current epoch that we should be fighting for<p>Has the <a href="https://www.britannica.com/science/Holocene-Epoch">Holocene epoch of the past 11,700 years</a> been supplanted by the <a href="https://education.nationalgeographic.org/resource/anthropocene/">proposed Anthropocene epoch</a> of today? Although it’s broadly accepted that planetary systems have changed as a result of human influence, a panel of experts at the International Union of Geological Sciences answered a firm “no” when they <a href="https://doi.org/10.1038/d41586-024-00868-1">recently voted down recognizing the start of the new epoch</a>. </p>
<p>Does this mean that humans haven’t actually changed the planet? <a href="https://theconversation.com/the-anthropocene-is-not-an-epoch-but-the-age-of-humans-is-most-definitely-underway-224495">Not at all</a> and while we may not officially be in a geological Anthropocene, the term will likely persist in reference to human environmental interference in years to come. As such, the wake of this vote is perhaps the best moment to consider a more essential question: what will we do next? </p>
<p>Can we take the official rejection on an Anthropocene epoch as an implicit vote of confidence in our ability to return the planet to Holocene-like conditions? Is climate change reversible?</p>
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Read more:
<a href="https://theconversation.com/crawford-lake-what-the-past-can-teach-us-about-urban-living-today-209764">Crawford Lake: What the past can teach us about urban living today</a>
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<p>As a <a href="https://www.iisd.org/ela/blog/back-to-basics-what-is-a-limnologist/">limnologist</a>, I can share insights from long-term research on lakes. And as one Canadian lake, <a href="https://www.theglobeandmail.com/canada/article-anthropocene-crawford-lake/">Crawford Lake, had been selected as the candidate “golden spike”</a> of the Anthropocene epoch, <a href="https://www.tvo.org/video/hope-in-the-age-of-climate-anxiety">what lakes tell us of human impacts, and recoveries from those impacts, may be worth considering</a>.</p>
<h2>Atomic age?</h2>
<p>There are elements of our future which cannot be undone. Although we can reduce future extinction rates, <a href="https://doi.org/10.1016/j.cub.2019.07.040">there is no coming back for the countless species that have disappeared due to human actions</a>. Likewise, a <a href="https://doi.org/10.1126/sciadv.adi5502">global human-caused redistribution of species is a permanent symptom of (and evidence for) the Anthropocene</a>. On the other hand, some measures of the Anthropocene seem inherently more ephemeral. </p>
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<a href="https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white image of a mushroom cloud." src="https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=812&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=812&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=812&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1021&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1021&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584464/original/file-20240326-18-rgxkh2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1021&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 from the Trinity test at Los Alamos, the first nuclear explosion in human history. The onset of atmospheric nuclear explosions has often been cited as the critical starting moment in the Anthropocene epoch.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>The residues of widespread nuclear weapons testing through the 1950s into the 1960s have <a href="https://doi.org/10.1177/20530196221149281">generally been seen as a particularly strong indicator of the Anthropocene</a>. Scientists find evidence of this in lakes around the world in the form of trace amounts of Plutonium and Cesium in the sediments deposited during this period. </p>
<p>A rapid drop in atmospheric bomb testing in 1963 — upon the signing of the Nuclear Test Ban Treaty — has created a unique <a href="https://doi.org/10.1177/0096340215581357">“bomb pulse” which represents a global, unequivocally human, fingerprint</a>. The bomb pulse was considered evidence for a 1950 Anthropocene epoch start date and was likely the most critical factor in defining the Anthropocene. </p>
<p>However, which global human signal is more important for us to consider today: the fact that humans created and tested nuclear weapons, or that this was just a “pulse” as nuclear-armed states came together globally to change behaviour?</p>
<h2>Tipping points</h2>
<p>The most useful insights from lakes may come from how they experience <a href="https://doi.org/10.1038/s41559-019-0797-2">tipping point dynamics</a>, particularly as it relates to <a href="https://www.nature.com/scitable/knowledge/library/eutrophication-causes-consequences-and-controls-in-aquatic-102364466/">eutrophication</a> (the excess growth of plants and algae in a body of water). </p>
<p>The widespread synthesis and application of fertilizers has caused eutrophication on a massive scale and has <a href="https://doi.org/10.1002/wat2.1373">taken a huge toll around the globe, particularly on aquatic ecosystems</a>. Past a critical tipping point, <a href="https://doi.org/10.1016/0169-5347(93)90254-M">eutrophication can fundamentally alter lakes</a>, replacing clear waters with turbid (cloudy), algae-dominated conditions <a href="https://doi.org/10.1093/biosci/bix106">and impaired ecosystem functions and services</a>. </p>
<p>When seen in this light, it becomes clear that eutrophication is <a href="https://doi.org/10.3389/fenvs.2019.00200">a defining characteristic of the Anthropocene</a>. However, it is a characteristic that can be reversed — although restoration is not always straightforward. </p>
<p>Lakes, along with other ecosystems that feature tipping point dynamics, can be hard to <a href="https://doi.org/10.1146/annurev.ecolsys.35.021103.105711">flip back once they’ve passed the critical turbidity threshold</a>. Reducing the loading of nutrients into waterways can effectively improve water quality and there is evidence these efforts are effective. However, it <a href="https://doi.org/10.1007/s10750-024-05478-6">might take decades to re-establish desirable conditions in impacted systems</a>. </p>
<p>In some cases, it might take over a century, or even millennia, <a href="https://doi.org/10.1038/s41561-018-0238-x">for watersheds to recover from human nutrient pollution</a>. </p>
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<figcaption><span class="caption">A brief explanation of the process of eutrophication produced by Atlas Pro.</span></figcaption>
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<p>Although the process of full recovery may sometimes be lengthy (at least in human, not geological, timescales), <a href="https://doi.org/10.1111/fwb.13701">rapid partial recoveries are possible</a>, as is the potential for <a href="https://doi.org/10.3389/fpls.2018.00194">intermediate lake conditions that fall outside of a simplified clear or turbid binary</a>. </p>
<p>Understanding the role of tipping point dynamics in lakes can provide a <a href="https://doi.org/10.1086/723892">useful framework for management and restoration strategies</a>, and at least bring us back to something perhaps similar to what was originally lost.</p>
<p><a href="https://theconversation.com/weaving-indigenous-and-western-ways-of-knowing-can-help-canada-achieve-its-biodiversity-goals-201063">Essential Indigenous knowledge</a> — <a href="https://doi.org/10.1111/1365-2656.13882">alongside natural history museums around the world</a> — can play a key role in retaining knowledge of how things were to help understand how our systems are changing, and what target conditions we might aim for in the near future.</p>
<h2>All is not lost</h2>
<p>This brings us back to our original question. To what degree is climate change reversible? Most world economies have <a href="https://www.un.org/en/climatechange/net-zero-coalition">committed to achieve net zero greenhouse gas (GHG) emissions</a>. To date, 2023 featured the highest global carbon dioxide emissions yet, but these emissions likely would have been lower than those in 2022 if not for <a href="https://www.iea.org/reports/co2-emissions-in-2023">droughts dampening hydroelectricity generation</a>. </p>
<p>To return to and stabilize ourselves within a desired Holocene-like climatic range, we will not only need to achieve net zero, but establish regenerative socio-economic systems that reduce atmospheric GHG concentrations in a sustainably just manner. </p>
<p>However, timing is crucial, <a href="https://doi.org/10.1038/d41586-019-03595-0">as globally connected tipping points</a> may <a href="https://doi.org/10.1038/s41561-023-01333-w">accelerate the natural release of GHGs from oceans</a>, <a href="https://doi.org/10.1126/sciadv.aay1052">on land</a> and in <a href="https://doi.org/10.1038/ngeo2795">inland waters</a>. </p>
<p>Put simply, while humans absolutely can stop burning fossil fuels, <a href="https://doi.org/10.3389/fsci.2023.1170744">we cannot guarantee how quickly our planet will cool</a>. Moreover, we cannot even guarantee that GHGs will decline with these actions — <a href="https://doi.org/10.1126/science.abn7950">particularly once our warming exceeds 1.5 C</a>. </p>
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<figcaption><span class="caption">A discussion on climate tipping points produced by the New York Times.</span></figcaption>
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<p>If there is anything to glean from the study of lakes, it might be that remediation is most effective before critical tipping points have been crossed. However, even beyond such tipping points, active remediation efforts are always worthwhile, if not outright necessary. </p>
<p>Systems governed by tipping point dynamics might not automatically bounce back, but they can substantially improve in the short term. Indeed, many affected systems can likely even eventually recover fully over decades to centuries if the appropriate rapid actions are taken.</p>
<p>Although none of this changes the recent outcome of the Anthropocene epoch being voted down, it may weigh on how we interpret that decision. The vote in no way implies that our species has not changed the world dramatically. Rather, it can remind us that the epoch we’re in, although perhaps unrecognizable, is not a lost one, and that we should muster all available resources and knowledge to return our planet to Holocene-like conditions as much as possible.</p>
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Read more:
<a href="https://theconversation.com/how-to-stay-hopeful-in-a-world-seemingly-beyond-saving-210415">How to stay hopeful in a world seemingly beyond saving</a>
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<p>The challenge lying ahead of us will be to work actively to ensure that our planet remains welcoming, for not just humans but all biodiversity. It is time we abandon any sense of defeatism that might be associated with the Anthropocene and focus on what really matters: saving this epoch before it is too late.</p><img src="https://counter.theconversation.com/content/225428/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Soren Brothers 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 recent rejection of the start of the Anthropocene epoch reminds us of the paramount importance of preserving what remains of our current Holocene.Soren Brothers, Allan and Helaine Shiff Curator of Climate Change, Royal Ontario Museum and Assistant Professor, Ecology and Evolutionary Biology, University of TorontoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2243312024-03-03T14:27:31Z2024-03-03T14:27:31ZNo, overwintering turtles don’t breathe through their butts: Getting to the bottom of a popular misconception<figure><img src="https://images.theconversation.com/files/579265/original/file-20240301-22-9mghi4.jpg?ixlib=rb-1.1.0&rect=0%2C10%2C1000%2C544&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Northern map turtles hibernate underwater during the winter.</span> <span class="attribution"><span class="source">(G. Bulté)</span></span></figcaption></figure><p>On a crisp February day, a filmmaker and I were walking across the 45-centimetre-thick ice covering Opinicon Lake, a small lake in eastern Ontario. We were heading for a very special spot where hundreds of <a href="https://ontarionature.org/programs/community-science/reptile-amphibian-atlas/northern-map-turtle/">northern map turtles</a> coalesce every year to spend the winter months. The filmmaker stuck a camera attached to a long pole in holes drilled through the ice to capture turtles for a nature documentary.</p>
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<a href="https://theconversation.com/northern-map-turtles-survive-cold-winter-conditions-by-staying-active-under-ice-195050">Northern map turtles survive cold winter conditions by staying active under ice</a>
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<p>As we spotted our first turtles on the monitor, the filmmaker confided that he would like to get a shot of a turtle’s rear end. Strange as it sounds, this request didn’t surprise me. The filmmaker wanted to show overwintering turtles breathing with their butts. I had disappointing news for him.</p>
<p>I can’t blame the filmmaker for expecting to observe this bizarre form of respiration in our overwintering turtles. A quick Google search turns up several stories about butt-breathing turtles, many from credible sources. </p>
<p>A handful of turtles <em>can</em> breathe through their butts — it’s called cloacal gas exchange — but they are distant relatives of the North American species often claimed to do so in winter. But as far as scientific evidence goes, North American turtles overwintering in ice-covered water bodies don’t survive by breathing through their butts.</p>
<h2>Mysterious cloacal sacs</h2>
<p>In turtles, as in other reptiles (<a href="https://evolution.berkeley.edu/what-are-evograms/the-origin-of-birds/">including birds</a>), the reproductive and digestive tracts merge into a single pipe called the cloaca. Some species of turtles have a pair of sacs sprouting from their cloacal passage. These sacs, called cloacal bursae, are different from the single urinary bladder. </p>
<p>The function of cloacal bursae has baffled anatomists and physiologists for more than two centuries. In 1998, C. Barker Jørgenson published a <a href="https://www.cambridge.org/core/journals/biological-reviews/article/abs/role-of-urinary-and-cloacal-bladders-in-chelonian-water-economy-historical-and-comparative-perspectives/010D5928EF15B4A15C9589034B29EE14">historical overview</a> of the research on these structures since their discovery. </p>
<p>According to Jørgensen, the anatomist Hans Gadow was the first to invoke a respiratory function for the sacs in a <a href="https://www.biodiversitylibrary.org/item/268756#page/9/mode/1up">1901 book called <em>Amphibia and Reptiles</em></a>. Gadow wrote that “these sacs, which have highly vascularised walls, are incessantly filled and emptied with water through the vent, and act as important respiratory organs.” </p>
<p>This suggestion of a respiratory function, Jørgenson pointed out, became widely accepted without any supporting evidence.</p>
<h2>Butt-breathing turtles</h2>
<p>Evidence of cloacal respiration did eventually come from research on Australian freshwater turtles, such as the <a href="http://dx.doi.org/10.2307/1447197">saw-shelled turtle</a> and the <a href="http://dx.doi.org/10.7882/AZ.2010.016">white-throated snapping turtle</a>. The inner surface of the bursae in these species is densely lined with tiny finger-like projections called papillae which are themselves packed with tiny blood vessels. The papillae appear to function like gills. </p>
<p>A turtle pumps water into its cloaca and the oxygen dissolved in the water is absorbed by the blood vessels in the papillae while carbon dioxide diffuses from the blood to the water. The turtle then expels the stale water out of its cloaca and pumps fresh water back in. Even when the water is warm and the demand for oxygen high, some of these Australian turtles remain submerged for hours, relying on their cloacal bursae to get the oxygen they need.</p>
<p>These findings are remarkable, but North American turtles do not have the same cloacal superpowers.</p>
<h2>Distant cousins</h2>
<p>All living turtles fall in one of two groups: the <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/cryptodira">hidden-necked</a> and the <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/pleurodira">side-necked</a>. The groups are named after the way the necks of their members bends.</p>
<p>More importantly, these two groups represent two branches in the turtle family tree. The Australian cloacal breathers are on the side-necked branch. These turtles are only found in the southern hemisphere. </p>
<p>All turtles living in the cold northern hemisphere are on the hidden-necked branch. The hidden-necked and side-necked branches split around <a href="https://doi.org/10.1073/pnas.2012215118">200 million years ago</a>. </p>
<p>Lots of evolution can happen in 200 million years. For context, placental mammals like us parted ways from our egg-laying cousins like the duck-billed platypus about 166 million years ago. </p>
<p>Side-necked and hidden-necked turtles have amassed many differences during their 200-million-years-long journey apart, despite their physical similarities. Some of these differences appear to be in their cloaca. </p>
<p>To date, there is no evidence that hidden-necked turtles — like painted turtles, sliders, map turtles and snapping turtles — <a href="https://www.proquest.com/docview/1981235671">sport the gas exchange hardware of their distant side-necked cousins</a>.</p>
<p>It is worth noting that not all turtles have cloacal bursae. For instance, the <a href="https://ontarionature.org/programs/community-science/reptile-amphibian-atlas/spiny-softshell/">spiny softshell</a> and the <a href="https://ontarionature.org/programs/community-science/reptile-amphibian-atlas/eastern-musk-turtle/">common musk turtle</a> lack them. </p>
<p>Both species range as far north as southern Canada where they spend several months under the ice every year.</p>
<h2>Breathing through the winter</h2>
<p>The first published suggestion that overwintering turtles employ cloacal gas exchange appeared in 1958. Herpetologists Hobart Smith and Louis James published a review on cloacal bursae, where they wrote: “It is our opinion that the presence of bursae indicates a capacity to survive under water at low temperatures for long periods.” </p>
<p>In a followup study, <a href="https://archive.org/details/MiscellaneaN178/mode/2up">published in 1961</a>, Smith experimentally tested the gas exchange hypothesis and failed to convincingly demonstrate a respiratory function for the bursae in several North American species known to overwinter in water. Successive attempts have showed no, or a minute amount of, gas exchange within the cloaca. </p>
<p>The most recent test of cloacal gas exchange in a hidden-necked turtle was led by the late physiologist Donald C. Jackson, author of <a href="https://www.hup.harvard.edu/books/9780674072305"><em>Life in a Shell: A Physiologist’s View of a Turtle</em></a>. In this 2004 study, Jackson and his collaborators examined <a href="http://dx.doi.org/10.1016/j.cbpb.2004.09.005">gas exchange in painted turtles</a> submerged in cold water.</p>
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<span class="caption">Painted turtles can survive for months without oxygen.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<p>Painted turtles, found throughout North America, have one of the longest overwintering periods of any aquatic turtles. Although they can survive for <a href="https://doi.org/10.1113/jphysiol.2002.024729">months without oxygen</a>, they can breathe underwater when oxygen is present. The physiologists experimentally manipulated the ability of painted turtles to breathe through their skin, mouth and cloaca to figure out which of these body parts are involved in gas exchange. </p>
<p>The researchers found no evidence that aquatic gas exchange took place in the cloaca, but showed that it was the turtles’ skin that performed this function.</p>
<h2>Hot air</h2>
<p>It is ironic that the one species in which cloacal gas exchange has been thoroughly rejected on morphological and physiological grounds is often used as the poster child for winter butt-breathing. The image of a turtle using its butt to breathe while locked under the ice for months is appealing, but as far as scientific evidence goes, it is nothing but hot air.</p>
<p>The notion that cloacal gas exchange helps North American turtles survive long winters trapped under the ice is pervasive in pop science, but to date, there is no solid evidence that hidden-necked turtles use cloacal gas exchange. The skin and mouth lining are where gas exchange happens during winter hibernation.</p>
<p>As for the cloacal bursae, their function in hidden-necked turtles remains unclear, but they may help control <a href="https://doi.org/10.1126/science.166.3913.1649">buoyancy in some species</a>.</p><img src="https://counter.theconversation.com/content/224331/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grégory Bulté 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>A phenomenon observed in a small group of organisms cannot always be generalized across a species — contrary to popular belief, overwintering turtles don’t breathe through their butts.Grégory Bulté, Instructor, Ecology and Evolutionary Biology, Carleton UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2151312023-11-19T13:00:27Z2023-11-19T13:00:27Z‘Forever contaminant’ road salts pose an icy dilemma: Do we protect drivers or our fresh water?<p>As winter approaches, many communities in Canada and around the world arm themselves against icy roads and sidewalks with a time-honoured ally: road salt. For decades, applying road salt has been regarded as a simple but vital tool in countering the dangers of slippery road conditions, but the downsides of its use are apparent with implications that <a href="https://doi.org/10.1007/s11270-018-4060-2">extend beyond the cold months</a>. </p>
<p>Scientists have long known that the substance which has safeguarded us through the colder months poses a threat to aquatic life and drinking water quality. But now we are finding that this chemical also <a href="https://doi.org/10.1016/j.scitotenv.2022.157336">disrupts the delicate balance of oxygen and nutrients</a> in our freshwater lakes and ponds. </p>
<p>Road salt, commonly referred to as rock salt, is a mixture primarily composed of sodium chloride (NaCl). It is used to de-ice roads and highways during winter to enhance safety by preventing the formation of ice and reducing slippery conditions. Road salt persists as an environmental contaminant due to its chemical stability and the cyclic nature of its dispersal. </p>
<p>Introduced through activities like road de-icing, salts move from roads to surface water such as streams and lakes, groundwater, remaining indefinitely in the environment without significant degradation. The continual cycling and lack of substantial transformation underscore the long-term impact of sodium chloride as a “forever contaminant.”</p>
<p>With a growing awareness of its ecological repercussions, a critical dilemma emerges. Do we prioritize driver safety or acquatic ecosystem health?</p>
<h2>Negative impacts revisited</h2>
<p>The detrimental effects of road salt on aquatic ecosystems and drinking water supplies <a href="https://doi.org/10.1016/j.scitotenv.2021.150289">have long been recognized</a>. Its heavy application during winter months leads to a buildup of road salt ions in both soil and water bodies, altering their natural chemical composition. </p>
<p>These elevated salt concentrations can harm freshwater organisms and vegetation, change soil structure, and, when <a href="https://doi.org/10.1016/j.scitotenv.2023.166466">seeping into groundwater</a>, compromise the potable water supply of nearby communities.</p>
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<a href="https://theconversation.com/winter-road-salting-has-year-round-consequences-173621">Winter road salting has year-round consequences</a>
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<p><a href="https://doi.org/10.1016/j.scitotenv.2022.157336">Recent research</a> has shed light on a less conspicuous yet equally significant consequence of road salt usage: its contribution to oxygen depletion in lakes. The occurrence of <a href="https://doi.org/10.1029/2023JG007558">very low oxygen concentrations, or hypoxia, in a lake is generally attributed to an excessive input of nutrients, especially that of phosphorus</a>. </p>
<p>Nutrient enrichment can trigger algal blooms that, in turn, lower the oxygen level in the lake’s deeper waters. The continued expansion of hypoxic conditions deteriorates the lake’s water quality and may ultimately cause the die-off of most aquatic life. This nutrient-driven process, <a href="https://doi.org/10.5194/bg-14-3585-2017">known as eutrophication</a>, is affecting the ecological health of a growing number of lakes around the world.</p>
<h2>Salt and oxygen in water</h2>
<p><a href="https://doi.org/10.5194/egusphere-egu2020-16637">Phosphorus</a>, the nutrient frequently implicated in lake eutrophication, plays a multifaceted role in this scenario. <a href="https://doi.org/10.1016/j.scitotenv.2022.157336">Salinization</a> increases the density of the water reducing the mixing of the lake waters and. Consequently, this reduces the amount of oxygen that reaches the lake’s depths. </p>
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Read more:
<a href="https://theconversation.com/road-salt-makes-winter-driving-safer-but-what-does-it-do-to-the-environment-87860">Road salt makes winter driving safer, but what does it do to the environment?</a>
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<p>Oxygen depletion, paradoxically, favours the remobilization of phosphorus from the sediments accumulating at the bottom of the lake. That is, the sediments become an increasingly important <em>internal</em> source of phosphorus, escalating the nutrient enrichment of the lake. </p>
<p>In that way, salinization — driven by extensive road salt application — <a href="https://doi.org/10.1016/j.scitotenv.2022.157336">intensifies eutrophication symptoms</a> that are usually associated with phosphorus supplied to lakes from external sources in the surrounding landscape.</p>
<h2>Navigating the saline challenge</h2>
<p>Canada has been <a href="https://doi.org/10.1016/j.scitotenv.2021.151717">proactive in responding</a> to eutrophication. For instance, reduced phosphorus pollution in Lake Erie in the 1980s and 1990s led to significant <a href="https://doi.org/10.1029/2019WR025019">water quality improvements</a>. However, addressing accelerating salinization of lakes requires new thinking and innovative solutions that recognize the complexity of the issue. It’s not just de-icers, such as road salts, that need to be considered. </p>
<p><a href="https://doi.org/10.1098/rstb.2018.0019">Other sources of salt</a>, such as agricultural runoff, discharges from water softeners and other domestic activities and drainage from mine waste and geological salt deposits, are all part of the problem. Salinization is a <a href="https://doi.org/10.1073/pnas.1620211114">threat to water resources globally</a>, not just those of cold regions.</p>
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<figcaption><span class="caption">A brief overview of the process of eutrophication, produced by the National Oceanic and Atmospheric Administration.</span></figcaption>
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<p>Chloride, a key component of road salt, has earned the moniker of a “forever contaminant” <a href="https://doi.org/10.1016/j.scitotenv.2018.10.242">due to its persistence in soil and water systems</a>. When introduced into the environment, chloride ions readily dissolve into water <a href="https://doi.org/10.1016/j.scitotenv.2018.10.242">where they tend to remain</a>. </p>
<p>Over time, chloride not only accumulates in surface water bodies <a href="https://doi.org/10.1016/j.scitotenv.2023.166466">but also in groundwater</a>. In fact, ground (or subsurface) water has been identified as a persistent source of chloride to surface freshwater bodies, especially during the summer months. </p>
<p>While <a href="https://doi.org/10.2166/wqrjc.2011.105">proactive management practices have been introduced</a>, the accumulation of chloride and other problematic <a href="https://doi.org/10.1111/j.1747-6593.2012.00371.x">salt ions</a>, including sodium, in soil and water will require expensive and <a href="https://doi.org/10.2134/jeq2009.0108">time-consuming restoration efforts</a>. </p>
<h2>Paving the path to solutions</h2>
<p>To mitigate the impacts of salinization, evidence-based approaches are urgently required. Solutions and policy recommendations must promote the reduction of salt runoff from road salt applications and other sources, and establish effective and comprehensive monitoring programs. </p>
<p>We have much to learn from how we’ve successfully managed excessive nutrient pollution — these lessons can help inform salt management strategies that work hand in hand with water quality and climate change solutions.</p>
<p>One potential alternative to the application of road salts is to use other de-icers. This requires a cautious stance because, as history teaches us, replacing one troublesome chemical with another often comes with unexpected ecological consequences. </p>
<p>Thorough examination and research are vital to ensure that alternatives don’t inadvertently introduce new threats.</p>
<h2>Protecting people and ecosystems</h2>
<p>The stakes are high when it comes to road salts: compromised drinking water, shrinking aquatic habitats and long-term pollution from legacy salt stores in soil and groundwater requiring costly remediation. It’s imperative that research, investment and public awareness converge to address this challenge holistically. </p>
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<strong>
Read more:
<a href="https://theconversation.com/to-make-less-harmful-road-salts-were-studying-natural-antifreezes-produced-by-fish-153087">To make less-harmful road salts, we're studying natural antifreezes produced by fish</a>
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<p>The impacts of road salt’s application extend far beyond the icy surfaces it’s intended to protect us from. As winter approaches, policy should work towards protecting our ecosystems and the many services they provide.</p><img src="https://counter.theconversation.com/content/215131/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jovana received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>David L Rudolph receives funding from the Natural Sciences and Engineering Research Council of Canada, the Ontario Ministry of the Environment, Conservation and Parks and the Regional Municipality of Waterloo. </span></em></p><p class="fine-print"><em><span>Fereidoun received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>Nancy received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>Philippe received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>Jiangyue Ju 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>Increasing awareness of the dangers ‘forever chemical’ road salts pose to our fresh water systems highlights the urgent importance of finding new approaches to de-icing our roads.Jovana Radosavljevic, Postdoctoral Fellow, Ecohydrology Research Group, University of WaterlooDavid L Rudolph, Professor of Hydrogeology, Department of Earth & Environmental Sciences, University of WaterlooFereidoun Rezanezhad, Research Associate Professor, Department of Earth & Environmental Sciences, University of WaterlooJiangyue Ju, PhD Student in Earth and Environmental Sciences, University of WaterlooNancy Goucher, Knowledge Mobilization Specialist, University of WaterlooPhilippe Van Cappellen, Professor of Biogeochemistry and Canada Excellence Research Chair Laureate in Ecohydrology, University of WaterlooLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2158442023-11-16T10:40:17Z2023-11-16T10:40:17ZWhy the Pyrenees’ mountain lakes are turning green<figure><img src="https://images.theconversation.com/files/554285/original/file-20230921-21-xzmfew.jpg?ixlib=rb-1.1.0&rect=39%2C63%2C5232%2C3880&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Ayès lake, in the Ariège region of the Pyrenees.</span> <span class="attribution"><span class="source">Dirk S. Schmeller</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>I first set foot <a href="https://theconversation.com/pourquoi-le-rechauffement-climatique-saccelere-dans-les-pyrenees-173362">in the Pyrenees</a> in 2006. Two years later, I began a large-scale survey of mountain lakes and amphibian populations: from east to west, I covered more than 100 mountain lakes located in the eastern Pyrenees to the Béarn region (Pyrénées-Atlantiques).</p>
<p>For our various projects, we came back to sample the same lakes at least once a year. Over time, we noticed changes, in particular the increased growth of algae <a href="https://theconversation.com/dans-les-eaux-de-baignade-les-cyanobacteries-amies-ou-ennemies-204352">cyanobacteria</a> and sometimes dinoflagellates, the blue-green algae that turn many lakes green. Back in 2012, we informed the Pyrenees National Park (PNP) about our observations.</p>
<p>Over the years, I’ve seen many of these lakes change colour. Some have lost the clarity and blue we’ve all come to expect from a mountain lake, while others have started to take on a greenish hue or even a bright green, particularly at the end of summer.</p>
<p>This trend does not affect any one region more than another: it can be found in the Ariège Pyrenees, the central mountains of the Pyrenees, as well as the western Béarn region. This is not a rare, localised phenomenon, but a large-scale event that is set to spread over the coming years. We’re also seeing it on the other side of the border, in the Catalan Pyrenees, where my colleague Marc Ventura has been leading the <a href="http://www.lifelimnopirineus.eu/es/inicio">European Limnopirineus project</a>.</p>
<p>In the Alps, colleagues at the research centre for high-altitude ecosystems (<a href="https://creamontblanc.org/">in French: Centre de recherche des écosystèmes d’altitude, Crea</a>) have made a similar observation. Even in the <a href="https://www.nps.gov/articles/algal-booms-mountain-lakes.htm">Canadian Rockies</a>, a clear growth in algae has been observed.</p>
<p>We have identified four main causes of this greening of the lakes.</p>
<h2>1. More fish and algae, fewer crustaceans</h2>
<p>On the Catalan side, Marc Ventura first noticed that the presence of fish was contributing to the phenomenon, and that their eradication was turning the lakes back to a bluish hue. For those of you who might have a problem with the idea of “eradication”, it should be pointed out that the presence of fish in mountain lakes is not natural: it is the result of fish stocking carried out to promote recreational fishing.</p>
<p>To better understand the mechanisms at work, it is important to realise that the species present in mountain lake communities form a highly complex system, with a bewildering number of interactions. The disappearance of one species or a group of species from an aquatic system can lead to radical changes of the overall ecosystem (in this case, a mountain lake).</p>
<p>In the lakes studied, for example, it was observed that crustaceans were much less numerous or even absent in the presence of fish, particularly minnows, a very commonly introduced species in mountain lakes. Microcrustaceans in aquatic ecosystems filter water to ingest food, which is essentially made up of algae: in their absence, this imbalance allows algae to proliferate.</p>
<h2>2. Insecticides that kill crustaceans</h2>
<p>According to our <a href="https://theconversation.com/pyrenees-francaises-un-cocktail-toxique-impressionnant-detecte-dans-les-lacs-de-montagne-181860">own work</a> carried out in certain lakes, the absence or sharp reduction in crustaceans is also due to pollution. It is thought two insecticides in particular shoulder the blame: <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969722015492">permethrin and diazinon</a>, which are either used on livestock to protect them from stinging insects or are present in insect repellents used by tourists.</p>
<p>We have identified many other chemical molecules in lake water – <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969722015492">141 in total</a> – and the effect of this cocktail on aquatic food webs is currently unknown. It should be noted, however, that we are currently only able to detect a small proportion of the organic molecules, due to methodological limitations. The cumulative toxicity of all the pollutants emitted by humans in these environments therefore remains a mystery.</p>
<p>It is therefore likely that we are underestimating the overall impact of the large number of organic molecules on aquatic ecosystems in the mountains and elsewhere. But there is no doubt that, in the lakes we are studying, the increase in pollution is encouraging the disappearance of microcrustaceans and therefore the proliferation of algae.</p>
<h2>3. Livestock waste, nutrients for algae</h2>
<p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969722015492">Research</a> has indicated pollutants may come from livestock, which are treated against biting insects with Butox or similar veterinary treatments containing deltamethrin or permethrin. Applied to the skin, these insecticides penetrate the animal’s bloodstream before being excreted in urine and faeces.</p>
<p>The active molecule remains largely unchanged and enters the water, even though it is <a href="https://enveurope.springeropen.com/articles/10.1186/s12302-022-00710-3">highly toxic to crustaceans in mountain lakes</a> starting from a concentration of the order of a few nanograms per litre, which is tiny. By killing crustaceans, these insecticides profoundly alter the aquatic food web.</p>
<p>But that’s not all. Algae also need nutrients to grow. Cattle provide them by drinking from lakes before urinating and defecating in the water: these discharges contain a high concentration of nutrients (nitrates and phosphates, among others), and especially phosphates are needed by cyanobacteria, filamentous algae.</p>
<h2>4. Climate change</h2>
<p>Finally, algae appreciate the heat: they multiply with high growth rates during the summer months, particularly when the water temperature exceeds 20°C. The rise in temperature caused by climate change is therefore adding to the other factors. In 2022, the edge of Lake Lhurs, in the Béarn region of France, reached over 25°C at an altitude of almost 1,800 metres – a blessing for algae.</p>
<p>These are the main factors, but my research could uncover more in the future. The most important thing is to understand that they act in synergy: we kill crustaceans by introducing fish, we pollute by treating livestock and then, once the mountain aquatic ecosystems have been weakened, we contribute through our activities to increasing the temperature of the lakes: algae then find the ideal conditions for growth. Some of these <a href="https://www.sciencedirect.com/science/article/pii/S0043135423009879">algae are toxic</a> and therefore present a health risk.</p>
<p>Our lakes thus change from blue to greenish, from greenish to bright green: no mystery to this, their colour simply reveals what we are inflicting on our mountain lakes, our water resources, wildlife, livestock and ourselves.</p>
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<figcaption><span class="caption">Mountain lake ecosystem health indicators (“Mountains, a fragile source of life”, 21 September 2023).</span></figcaption>
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<h2>How to get clear, blue lakes back</h2>
<p>Fortunately, all is not lost. The work of <a href="https://www.researchgate.net/publication/361705726_Non-native_minnows_cause_much_larger_negative_effects_than_trout_on_littoral_macroinvertebrates_of_high_mountain_lakes">Marc Ventura</a> highlights that it is still possible to turn back the clock and return lakes to a blue colour and healthy ecosystems. But this means changing the management of all the mountain lakes.</p>
<p>First, it is essential to limit fish stocking to certain large lakes and ban it in the others, so that they are reserved for local flora and fauna. Even in the large lakes, areas that are inaccessible to fish can be created to encourage invertebrates, amphibians and other aquatic and semi-aquatic species.</p>
<p>The next step is to reduce the pollution caused by tourists, livestock and industry. In particular, by communicating and discussing with the various stakeholders, alerting them to the risks and working with them to find real solutions rather than unsatisfactory compromises.</p>
<p>For example, the Ariège Pyrenees Regional Nature Park has begun to raise awareness among tourists, at least about the use of sun creams. This is a first step, albeit an insufficient one given the range of problems explained here. Another step forward would be to limit cattle access to mountain lakes, which would also help to restore the ecosystems. Finally, on a larger scale, the phenomenon is yet another reminder of the urgent need to combat climate change…</p>
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<img alt="" src="https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308798/original/file-20200107-123373-wmivra.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>Created in 2007 to help accelerate and share scientific knowledge on key societal issues, the Axa Research Fund has supported nearly 700 projects around the world conducted by researchers in 38 countries. To learn more, visit the site of the Axa Research Fund or follow on Twitter @AXAResearchFund.</em></p>
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<p><em>The <a href="https://anr.fr/Projet-ANR-21-BIRE-0002">BiodivRestore</a> project is supported by the French National Research Agency (ANR), which funds project-based research in France. Its mission is to support and promote the development of fundamental and applied research in all disciplines, and to strengthen the dialogue between science and society. For more information, visit the <a href="https://anr.fr/">ANR website</a>.</em></p><img src="https://counter.theconversation.com/content/215844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dirk S. Schmeller has received funding from the ANR and AXA Research Fund.</span></em></p>Many mountain lakes in the Pyrenees have turned green, a phenomenon that is a warning about the multiple pressures on ecosystems.Dirk S. Schmeller, Directeur de recherche CNRS, Expert for Conservation Biology, Axa Chair for Functional Mountain Ecology at the École Nationale Supérieure Agronomique de Toulouse, Centre national de la recherche scientifique (CNRS)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2151132023-10-09T17:19:25Z2023-10-09T17:19:25ZLough Neagh: UK and Ireland’s largest lake is being suffocated by business and agricultural interests<p><a href="https://www.britannica.com/place/Lough-Neagh">Lough Neagh</a> is the largest freshwater lake in the UK and Ireland. It is a protected area of special scientific interest and the source of <a href="https://www.niwater.com/news-detail/12350/Your-water-is-safe-to-drink/">40% of Northern Ireland’s drinking water</a>. </p>
<p>But it’s also the site of a severe environmental crisis and a public health emergency. Located about 20 miles west of Belfast, the lough has turned thick with <a href="https://www.gov.uk/government/publications/algal-blooms-advice-for-the-public-and-landowners/algal-blooms-advice-for-the-public-and-landowners">toxic blue-green algae</a>, resulting in the demise of both <a href="https://www.belfasttelegraph.co.uk/news/environment/out-of-control-lough-neaghs-poisonous-bacteria-now-killing-swans-foxes-and-dogs/a1026634162.html">its own wildlife and people’s pets</a>. </p>
<p>This situation has brought about a <a href="https://www.bbc.co.uk/news/uk-northern-ireland-66835897">sense of mourning</a> among local people and activists who, in September 2023, held a “wake” to highlight their fears that the lough is dying. Lough Neagh’s historic fishing industry, which is known for its <a href="https://www.loughneagheels.com/sustainability/">use of sustainable and traditional methods</a>, also faces the <a href="https://www.irishnews.com/news/northernirelandnews/2023/09/15/news/fishing_for_lough_neagh_eels_world_renowned_has_collapsed_fishermen_locals-3617503/">threat of collapse</a> unless conditions improve.</p>
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<p>Multiple factors have made Lough Neagh particularly vulnerable to these perilous algal blooms, including <a href="https://www.sciencedirect.com/science/article/pii/S0043135411004386#bib63">rising water temperatures</a> linked to global warming. However, the root causes of this crisis are decades of <a href="https://friendsoftheearth.uk/nature/lough-neagh-why-europes-wildlife-jewel-needs-space-breathe#:%7E:text=Dredging%20is%20a%20risk%20to%20waterfowl%2C%20fish%20populations%2C,Lough%20Neagh%20could%20fill%20over%2010%2C000%20volleyball%20courts.">sand dredging</a> and pollution stemming from <a href="https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2007.52.1.0354">agricultural runoff</a>, <a href="https://www.theguardian.com/environment/2021/dec/15/7m-tonnes-of-raw-sewage-a-year-discharged-into-northern-irish-rivers">sewage treatment</a> and <a href="https://niopa.qub.ac.uk/bitstream/NIOPA/3436/1/11015.pdf">septic tanks</a>. These activities have flooded the lough with nutrients on which the blue-green algae are thriving.</p>
<p>This crisis is far from a freak accident. It is the consequence of political negligence and institutional mismanagement, driven by an economy that has long prioritised growth over all else. </p>
<p>The same dynamic is responsible for the fragile state of nature throughout the rest of Northern Ireland. A <a href="https://stateofnature.org.uk/wp-content/uploads/2023/09/TP25999-State-of-Nature-main-report_2023_FULL-DOC-v12.pdf">recent report</a> found that 12% of Northern Ireland’s wild species are now facing extinction. </p>
<p>Any economy that presupposes the exploitation of finite natural resources to fuel the endless exponential growth it needs to function and survive cannot be sustained indefinitely. The crisis at Lough Neagh illustrates the grave consequences of attempting to do so. </p>
<p>It has become a place for extracting resources and a dump site for the chemical byproducts of agricultural activities that seek to produce as much as possible at the lowest financial cost. </p>
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<img alt="Farm machinery collecting silage in a field." src="https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552748/original/file-20231009-25-8awptl.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">Northern Ireland’s landscape and biodiversity have been altered by the agricultural and food manufacturing industry.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ballycastle-uk-0622-agriculture-collecting-silage-1523474765">Steve Allen/Shutterstock</a></span>
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<h2>Going for Growth</h2>
<p>Much of the groundwork for Northern Ireland’s current environmental crisis was laid in 2013 by the Department of Agriculture, Environment and Rural Affairs’ (Daera) landmark “<a href="https://www.daera-ni.gov.uk/publications/going-growth-strategic-action-plan-support-ni-agri-food-industry">Going for Growth</a>” policy. </p>
<p>The policy promotes more market-led innovation and sales growth in highly competitive international markets. As a result, it has spurred the greater use of phosphates, nitrogen and other inputs within Northern Ireland’s agricultural system. </p>
<p>It has also provided farmers with an incentive to <a href="https://link.springer.com/article/10.1007/s10612-020-09488-3">intensify their beef and dairy production</a>. This has led to the increased production of slurry. When slurry leaks into the environment, it has the potential to pollute water catchments and waterways.</p>
<p>The Going for Growth strategy was developed in the context of a general push for economic growth as part of Northern Ireland’s “<a href="https://labourafterconflict.org/wp-content/uploads/2012/05/DoubleTransition.pdf">double transition</a>”, from war to peace and towards neoliberalism. Declared as “open for business” by political leaders, Northern Ireland has since become an attractive destination for various forms of socially and environmentally detrimental extractive economic activities.</p>
<p>These activities include <a href="https://www.bbc.co.uk/news/uk-northern-ireland-53213878">gold mining in the Sperrin Mountains</a>. Dalradian, the company proposing the project, claims the mine could provide a £750 million boost to the Northern Ireland economy.</p>
<figure class="align-center ">
<img alt="Cows by the roadside in Northern Ireland." src="https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552751/original/file-20231009-21-ekha7v.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">Beef and dairy production in Northern Ireland has intensified since 2013.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cows-by-roadside-northern-ireland-1151460356">AU Media/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Institutional mismanagement</h2>
<p>The environmental impact of the Going for Growth strategy has been compounded by a general lack of regulatory oversight, policing and punishment of the pollution that accompanies it. </p>
<p>Still today, Northern Ireland does not have an independent environmental protection agency. The regulatory body it does have, the Northern Ireland Environment Agency, is part of Daera, the very government department tasked with promoting growth within and through the agriculture and food manufacturing industry.</p>
<p>The unfettered way in which growth is promoted and pursued shows how short-term economic interests have been prioritised to the detriment of the future viability of sustainable food production and ecological stability in Northern Ireland. There is an absence of suitable policies and initiatives to support rapid change towards a sustainable food system and a just transition for farmers. </p>
<h2>Powerful vested interests</h2>
<p>These failures of governance are further complicated at Lough Neagh by a messy network of stakeholders with vested interests in its economic, rather than social and ecological value. This includes a colonial legacy of ownership, through which the <a href="https://www.bbc.co.uk/news/av/uk-northern-ireland-67006058">Earl of Shaftesbury</a> enjoys the rights of an “absentee landlord” over the lough’s bed and soil, even though its water is publicly owned. </p>
<p>The earl profits from these “business assets” through royalties from sand dredging. However, he argues that the current state of the water in Lough Neagh is not his responsibility and won’t relinquish his private ownership without significant compensation from public funds. In the past, the amount of compensation he would require has been estimated to stand at £6 million.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1709670221823254618"}"></div></p>
<p>This network of stakeholders also includes a politically powerful agricultural sector. The sector has been <a href="https://www.sciencedirect.com/science/article/pii/S0743016720301340?casa_token=MRJIMlj84J4AAAAA:N6xfFl70q8BmGO64LJff29uNZpLCEa6s2Gdqls0J1aMpuCTpElReKRRtX_Efj0Omf60RWLyf">successful in lobbying</a> for reduced government oversight and increased state financial support. </p>
<p>Meanwhile, local people are disenfranchised in their ability to influence how the lough, the largest ecological commons on the island of Ireland, is managed and to whose benefit. </p>
<p>Given the political, regulatory and powerful vested interests involved, alongside issues with mismanagement, perhaps the real question here is not how and who is responsible for killing Lough Neagh but rather why this decline did not happen sooner.</p>
<p>Our only hope now is that this situation serves as a catalyst for Northern Ireland to rectify its practices and start on a path towards environmental restoration.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>John Barry receives funding from the ESRC. </span></em></p><p class="fine-print"><em><span>Founder of Love Our Lough, a collective set up to cherish, protect and celebrate the beautiful Lough Neagh. </span></em></p><p class="fine-print"><em><span>Calum McGeown 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 largest lake in the UK and Ireland has been blighted by toxic blue-green algae.Calum McGeown, Research Assistant at the Centre for Sustainability, Equality and Climate Action, Queen's University BelfastJohn Barry, Professor of Green Political Economy, Queen's University BelfastLouise Taylor, Early Career Researcher and Ecotherapist., Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2129242023-09-06T12:26:36Z2023-09-06T12:26:36ZInvasive species cause billions of dollars in damage worldwide: 4 essential reads<p>Invasive species – including plants, animals and fish – cause heavy damage to crops, wildlife and human health worldwide. Some prey on native species; other out-compete them for space and food or spread disease. A new United Nations report estimates the losses generated by invasives at <a href="https://zenodo.org/record/8314303">more than US$423 billion yearly</a> and shows that these damages have at least quadrupled in every decade since 1970.</p>
<p>Humans regularly move animals, plants and other living species from their home areas to new locations, either accidentally or on purpose. For example, they may import plants from faraway locations to <a href="https://theconversation.com/invasive-grasses-are-fueling-wildfires-across-the-us-126574">raise as crops</a> or bring in a nonnative animal to <a href="https://theconversation.com/everyone-agreed-cane-toads-would-be-a-winner-for-australia-19881">prey on a local pest</a>. Other invasives <a href="https://theconversation.com/the-invasive-emerald-ash-borer-has-destroyed-millions-of-trees-scientists-aim-to-control-it-with-tiny-parasitic-wasps-158403">hitch rides in cargo</a> or <a href="https://theconversation.com/ballast-water-management-is-reducing-the-flow-of-invasive-species-into-the-great-lakes-190880">ships’ ballast water</a>.</p>
<p>When a species that is not native to a particular area becomes established there, reproducing quickly and causing harm, it has become invasive. These recent articles from The Conversation describe how several invasive species are causing economic and ecological harm across the U.S. They also explain steps that people can take to avoid contributing to this urgent global problem.</p>
<h2>1. The best intentions: Callery pear trees</h2>
<p>Many invasive species were introduced to new locations because people thought they would be useful. One example that’s widely visible across the U.S. Northeast, Midwest and South is the Callery pear (<em>Pyrus calleryana</em>), a flowering tree that botanists brought to the U.S. from Asia more than 100 years ago. </p>
<p>Horticulturists loved the Callery pear for landscaping and wanted to produce trees that all grew and bloomed in the same way. As University of Dayton plant ecologist <a href="https://scholar.google.com/citations?user=uRA-SZ0AAAAJ&hl=en&oi=sra">Ryan W. McEwan</a> explained, they created identical clones from cuttings of trees with the desired characteristics – a process called grafting. Unlike some trees, a Callery pear can’t fertilize its flowers with its own pollen, so plant experts thought it wouldn’t spread.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1i8hL2mhCpM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Missouri state foresters explain why Callery pear trees became so popular and the problems they cause.</span></figcaption>
</figure>
<p>However, “as horticulturalists tinkered with Callery pears to produce new versions, they made the individuals different enough to <a href="https://theconversation.com/once-the-callery-pear-tree-was-landscapers-favorite-now-states-are-banning-this-invasive-species-and-urging-homeowners-to-cut-it-down-198724">escape the fertilization barrier</a>,” McEwan wrote. As wind and birds spread the trees’ seeds, wild populations of the trees became established and started crowding out native species. </p>
<p>Today, Callery pear trees are such scourges that several states have banned them. Others are paying residents to cut them down and replace them with native plants. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/once-the-callery-pear-tree-was-landscapers-favorite-now-states-are-banning-this-invasive-species-and-urging-homeowners-to-cut-it-down-198724">Once the Callery pear tree was landscapers' favorite – now states are banning this invasive species and urging homeowners to cut it down</a>
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</p>
<hr>
<h2>2. Tiny organisms, big impacts: Zebra and quagga mussels</h2>
<p>Invasive species don’t have to be large to cause outsized damage. Zebra and quagga mussels – shellfish the size of a fingernail – invaded the Great Lakes in the 1980s, clogging water intake pipes and out-competing native mollusks for food. Now they’re spreading west via rivers, lakes and bays, threatening waters all the way to the Pacific coast and Alaska.</p>
<p>As Rochester Institute of Technology environmental historian <a href="https://www.researchgate.net/scientific-contributions/Christine-Keiner-2071802254">Christine Keiner</a> wrote, it took several decades for the U.S. and Canada to regulate ships’ management of their ballast water tanks, which was the route by which the mussels were introduced to North America. </p>
<p>“Now, however, other human activities are increasingly contributing to harmful freshwater introductions – and with shipping regulated, the main culprits are <a href="https://theconversation.com/the-westward-spread-of-zebra-and-quagga-mussels-shows-how-tiny-invaders-can-cause-big-problems-185286">thousands of private boaters and anglers</a>,” Keller wrote. Limiting the destructive impacts of invasive species “requires scientific, technological and historical knowledge, political will and skill to persuade the public that everyone is part of the solution.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Infographic showing locations on a motorboat to check for invasive mussels." src="https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546519/original/file-20230905-29-ibkd25.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"></a>
<figcaption>
<span class="caption">Many states require boaters to clean and dry their boats after use to avoid spreading zebra and quagga mussels.</span>
<span class="attribution"><a class="source" href="https://neinvasives.com/stop-aquatic-hitchhikers">Nebraska Invasive Species Program</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
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<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-westward-spread-of-zebra-and-quagga-mussels-shows-how-tiny-invaders-can-cause-big-problems-185286">The westward spread of zebra and quagga mussels shows how tiny invaders can cause big problems</a>
</strong>
</em>
</p>
<hr>
<h2>3. Threatening entire ecosystems: Lionfish</h2>
<p>When an invasive species is especially successful at spreading and reproducing, it can threaten the health of entire ecosystems. Consider the Pacific red lionfish (<em>Pterois volitans</em>), which has spread throughout the Caribbean and now is <a href="https://theconversation.com/invasive-lionfish-have-spread-south-from-the-caribbean-to-brazil-threatening-ecosystems-and-livelihoods-199229">moving south along Brazil’s coast</a>. </p>
<p>Lionfish thrive in many ocean habitats, from coastal mangrove forests to deepwater reefs, and they prey on numerous smaller fish species. In the Caribbean, they have reduced the number of small juvenile fish on reefs by up to 80% within as little as five weeks. </p>
<p>“Scientists and environmental managers widely agree that the lionfish invasion in Brazil is a potential ecological disaster,” warned Brazilian marine ecologist <a href="https://scholar.google.com.au/citations?user=_ArEYYMAAAAJ&hl=en">Osmar J. Luiz</a> of Charles Darwin University. “Brazil’s northeast coast, with its rich artisanal fishing activity, stands on the front line of this invasive threat.”</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1692994189099700515"}"></div></p>
<p>Although the Brazilian government was slow to address the lionfish threat, Luiz asserted that “with strategic, swift action and international collaboration, it can mitigate the impacts of this invasive species and safeguard its marine ecosystems.” That will require many techniques, from recruiting coastal residents to monitor for the invaders to tracking lionfish subpopulations using DNA analysis. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/invasive-lionfish-have-spread-south-from-the-caribbean-to-brazil-threatening-ecosystems-and-livelihoods-199229">Invasive lionfish have spread south from the Caribbean to Brazil, threatening ecosystems and livelihoods</a>
</strong>
</em>
</p>
<hr>
<h2>4. The value of acting locally</h2>
<p>Public awareness is critical for stemming the spread of many invasive plants and animals. That can involve actions as simple as cleaning your shoes and socks after a hike. </p>
<p>“Certain species of nonnative invasive plants produce seeds <a href="https://theconversation.com/those-seeds-clinging-to-your-hiking-socks-may-be-from-invasive-plants-heres-how-to-avoid-spreading-them-to-new-locations-195697">designed to attach to unsuspecting animals or people</a>. Once affixed, these sticky seeds can be carried long distances before they fall off in new environments,” explains Boise State University ecology Ph.D. candidate <a href="https://scholar.google.com/citations?user=nmAblPEAAAAJ&hl=en&oi=ao">Megan Dolman</a>. </p>
<p>Research shows that recreational trails promote the introduction of invasive plant species into natural and protected areas, including national parks and scenic trails.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CkgNbwptsgc/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>In her research, Dolman found that few Appalachian Trail hikers were aware of the risk of carrying invasive plant seeds on their shoes or socks, so they typically did not take steps such as cleaning their gear before and after hiking. By knowing about invasive species in their areas and ways to manage them, people can help protect special places and keep invasive species from spreading.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/those-seeds-clinging-to-your-hiking-socks-may-be-from-invasive-plants-heres-how-to-avoid-spreading-them-to-new-locations-195697">Those seeds clinging to your hiking socks may be from invasive plants – here's how to avoid spreading them to new locations</a>
</strong>
</em>
</p>
<hr>
<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/212924/count.gif" alt="The Conversation" width="1" height="1" />
According to a new UN report, invasive species do more than US$423 billion in damage worldwide every year. Four articles explore examples, from mollusks to poisonous fish.Jennifer Weeks, Senior Environment + Cities Editor, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1950502023-08-28T20:43:17Z2023-08-28T20:43:17ZNorthern map turtles survive cold winter conditions by staying active under ice<figure><img src="https://images.theconversation.com/files/544833/original/file-20230825-27248-hk37fo.jpg?ixlib=rb-1.1.0&rect=0%2C49%2C4683%2C3063&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As climate change increases temperatures, it is important to understand how freshwater turtles survive the winter.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/northern-map-turtles-survive-cold-winter-conditions-by-staying-active-under-ice" width="100%" height="400"></iframe>
<p>Imagine it’s winter, and you’re standing on a frozen lake or pond, when suddenly below your feet you notice hundreds of turtles. What are they doing down there below the ice? </p>
<p>Freshwater turtles in temperate regions like Canada spend several months of the year braced against frigid winter conditions of temperatures around or below 0 C <a href="https://doi.org/10.1093/biosci/biab032">and the formation of ice on water bodies</a>. </p>
<p>For all <a href="https://www.natureconservancy.ca/en/what-we-do/resource-centre/featured-species/turtles-of-canada.html">eight species of freshwater turtles in Canada</a>, this ice barrier — and more importantly the liquid water below it — is a refuge from the freezing temperatures above. While ice coverage protects these turtles from the harsh cold, it also presents them with a challenge: restricted access to atmospheric oxygen.</p>
<h2>Life under ice</h2>
<p>Some species, like snapping turtles (<em>Chelydra serpentina</em>) and painted turtles (<em>Chrysemys picta</em>), are <a href="https://doi.org/10.1017/S1464793106007032">perfectly comfortable spending several months submerged in water depleted in oxygen</a>. However, some species do not fare as well without oxygen and can only survive a few weeks at a time if submerged without adequate oxygen. These species need to extract the oxygen dissolved in the water to survive.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a turtle visible under frozen ice" src="https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544831/original/file-20230825-27-vpciz1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A snapping turtle under ice in southern Ontario.</span>
<span class="attribution"><span class="source">(Lucas Foerster/iNaturalist)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The northern map turtle (<em>Graptemys geographica</em>) is an example of such a species. They have also been observed engaging in locomotor activity — they keep moving around under the ice during the winter.</p>
<p>Northern map turtles were observed over a century ago by <a href="https://journals.iupui.edu/index.php/ias/article/view/14633/14709">marine biologists Barton Warren Evermann and Howard Walton Clark</a>. </p>
<p>During a dive at a communal hibernation site in November 1991 in Vermont, marine biologists observed <a href="https://www.biodiversitylibrary.org/item/106990#page/537/mode/1up">map turtles walking across the bottom of a river before ice coverage when temperatures were dropping to near 0 C</a>. </p>
<p>These observations lead us to believe that this behaviour may be important to a map turtle’s ability to survive the winter. Why else would they tap into their limited winter energy stores to move?</p>
<p>But how much do turtles really move in the winter?</p>
<h2>Advances in technology</h2>
<p>To track the movement of northern map turtles under the ice, our team glued tri-axial accelerometers — a type of biologging device that collects data — on 40 turtles at a known overwintering site in eastern Ontario. These devices recorded the movement, depth and temperature of the turtles for the seven months they remained under the ice. </p>
<p>Tri-axial accelerometers function similarly to a FitBit or Apple Watch — the devices produce <a href="https://doi.org/10.1111/j.2041-210X.2010.00057.x">a value called overall dynamic body acceleration</a>. This number is a measure of how much each turtle moves on a daily basis. </p>
<p>Combining this information with measurements of depth and temperature, we were able to paint a detailed picture of each turtle’s behaviour without ever seeing them. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a turtle swims underwater with a device attached to its back" src="https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/498317/original/file-20221130-22-kthfq4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A northern map turtle swims underwater with a tri-axial accelerometer attached to its back.</span>
<span class="attribution"><span class="source">(Grégory Bulté)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Daily movement</h2>
<p>Our findings surprised us. The data showed that northern map turtles move, albeit locally, every day of the winter. While that may look different across individuals, the interesting thing here is that movement is indeed continuous throughout the winter and not that different than in the weeks before the ice locks them in for the winter. </p>
<p>Although we expected some level of activity based on previous observations, we did not expect the turtles to be so fidgety all winter long. </p>
<p>Oxygen appears to be <a href="https://doi.org/10.1139/cjz-2022-0100">in short supply under the ice</a>, and map turtles cannot live without it for very long, so one would expect them to take it easy to limit their oxygen consumption. Our devices also told us the turtles were milling about in water hovering around 1 C, <a href="https://doi.org/10.1139/cjz-2022-0100">a temperature at which most reptiles become uncontrollably lethargic</a>.</p>
<p>Staying cool may in fact be what allows turtles to remain active. It’s likely that by staying at near-freezing temperatures, map turtles can slow their metabolic demands, thereby decreasing their need for oxygen and extending their use of this limited resource. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/DyOZf2qC5Ik?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A video showing underwater northern map turtle activity during the winter.</span></figcaption>
</figure>
<h2>Implications of movement</h2>
<p>We suspect that map turtles remain active in winter to meet their need for oxygen in order to survive the winter. Small amounts of activity may allow this species to replace the oxygen-depleted boundary layer of water on their skin with freshly oxygenated water. This would enhance their ability to “breathe” through their skin. </p>
<p>Alternatively, movement may be necessary for turtles as they look for micro-climates within their environment that have higher concentrations of oxygen or preferred temperature and depth profiles. In doing so, map turtles may be able to better need their physiological needs and oxygen requirements through the entirety of winter. </p>
<p>Much of what we know about reptiles in temperate regions is based on research done during the months which they are conspicuous. We are thus missing out on a big chunk of their annual cycle. As global temperatures continue to change, it is increasingly important to understand the winter part of a reptile’s lifecycle so we can plan how climate change may impact these animals.</p><img src="https://counter.theconversation.com/content/195050/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jessica Robichaud received funding from Carleton University, Natural Sciences and Engineering Research Council (NSERC), the Canadian Foundation for Innovation and the Ontario Research Fund Small Infrastructure Fund.</span></em></p>Freshwater turtles in Canada survive the cold, harsh winters by remaining under ice and conserving their energy. Northern map turtles however, move around constantly beneath the ice.Jessica Robichaud, PhD Student, Aquatic ecology, Carleton UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2094872023-07-12T20:04:25Z2023-07-12T20:04:25Z‘Humanity’s signature’: study finds plastic pollution in the world’s lakes can be worse than in oceans<p>A world-first study has found concentrations of plastics in some lakes are higher than in the most contaminated parts of oceans, demonstrating the extent to which plastics have invaded Earth’s ecosystems.</p>
<p>In a study <a href="https://www.nature.com/articles/s41586-023-06168-4">released today</a>, researchers sampled 38 lakes and reservoirs around the world, including in Australia, the United States, United Kingdom and Europe. Plastics and microplastics were found at every site, including very remote locations.</p>
<p>Lakes are sentinels for human activity. Many lakes are already suffering from issues such as algal blooms, deoxygenation, over-extraction and drying. Plastic contamination adds yet another threat to these highly stressed ecosystems.</p>
<h2>The plastics problem</h2>
<p>After plastics enter the environment, they generally break up and become smaller and smaller. Eventually they become microplastics – defined as particles less than 5 mm in size. </p>
<p>Plastic takes decades to disappear. It can <a href="https://oceanservice.noaa.gov/facts/microplastics.html">harm</a> ocean and aquatic life and contaminate water used by humans. </p>
<p>Plastics can be washed into lakes from the adjacent land areas. Lake water can sit for a long time without being flushed out, allowing plastics to accumulate.
We don’t yet know much about whether microplastics are absorbed by filter feeding organisms such as clams, mussels and zooplankton, and how plastics affect the food chain.</p>
<p>Plastic debris is widespread in freshwater ecosystems. But much of the focus has been on marine ecosystems, and knowledge of the scope of the problem in lakes and reservoirs has been hampered by a lack of appropriate data. Our research set out to close this gap.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/plastic-pollution-threatens-birds-far-out-at-sea-new-research-209081">Plastic pollution threatens birds far out at sea – new research</a>
</strong>
</em>
</p>
<hr>
<h2>What we did</h2>
<p>A global team of scientists, of which we were part, examined the abundance and type of plastic debris in freshwater ecosystems. Surface waters were sampled in 38 lakes and reservoirs across 23 countries (mostly in the Northern Hemisphere) and six continents.</p>
<p>Importantly, we used a standardised collection and analysis method, including very fine plankton nets to sample the plastic debris. These steps allowed for comparisons between lakes. </p>
<p>Broadly, we found plastic debris in all lakes studied. Most plastics were in the microplastic size range. However, concentrations varied widely. </p>
<p>Some 21 lakes had low concentrations – below one particle per cubic metre (m³). Of the remainder, 14 lakes had concentrations between one and five particles per m³ and three lakes had concentrations higher than five particles per m³.</p>
<p><a href="https://en.wikipedia.org/wiki/Forest_Lake,_Queensland">Forest Lake</a> in Brisbane was the Australian study site. It’s a popular urban lake used by many people for recreation. This lake had three plastics particles per cubic metre, ranking it sixth worst among the 38 lakes sampled. </p>
<p>The three most polluted lakes were, in order, Lake Lugano (Switzerland, Italy), Lake Maggiore (Italy) and Lake Tahoe (US). </p>
<p>In each of these lakes, plastic concentrations reached or exceeded those in “floating garbage patches” – marine areas collecting large amounts of debris, such as the <a href="https://education.nationalgeographic.org/resource/great-pacific-garbage-patch/">Great Pacific Garbage Patch</a>. These ocean areas were previously thought to be the worst cases of plastic pollution in water environments. </p>
<p>These three polluted lakes – as well as the heavily contaminated Lough Neagh in Northern Ireland – are also important sources of drinking water for local communities.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whales-and-dolphins-found-in-the-great-pacific-garbage-patch-for-the-first-time-122538">Whales and dolphins found in the Great Pacific Garbage Patch for the first time</a>
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</em>
</p>
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<figure class="align-center ">
<img alt="hands sorting plastic debris" src="https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.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 crew sorting plastic debris collected from the Great Pacific Garbage Patch in 2019.</span>
<span class="attribution"><span class="source">The Ocean Cleanup</span></span>
</figcaption>
</figure>
<h2>Where is the plastic coming from?</h2>
<p>The second part of our study sought to identify the landscape factors affecting the abundance and type of plastic debris.</p>
<p>More than 90% of the plastic particles belonged to two shape categories: fibres and fragments. We even found textile fibres in lakes and reservoirs in remote areas with limited human presence, such as Avery Lake in the US state of Michigan.</p>
<p>Our analysis indicated two types of lake are particularly vulnerable to plastic contamination: those in highly urbanised and populated areas, and those with a large surface area.</p>
<p>The most common colour of plastic particle was black (30%), followed by transparent (24%), blue (18%) and white (13%). The low concentrations of particles in bright colours, such as red, suggests these more visible plastics may have been mistaken by aquatic organisms for food, and ingested.</p>
<h2>So what next?</h2>
<p>Marine environments are generally considered the final resting place for plastic debris. But our research confirms plastic concentrations in freshwater ecosystems can be higher than those in oceans. </p>
<p>Our results indicate that lakes play a major role in the global plastic cycle. This points to an urgent need to develop management policies to reduce plastic pollution in freshwater lakes. This, in turn, will help prevent plastics from entering waterways and ending up in marine systems.</p>
<p>We don’t know how much plastic debris ends up in water supplies. We suggest this gap be addressed as soon as possible, and the ecological harm caused by microplastics should become a global management and research priority.</p>
<p>Our study also underscores the urgent need for coordinated, systematic monitoring of plastic pollution.</p>
<p>Sadly, it seems no lake can be considered truly “pristine” with respect to plastic pollution. Our research serves as yet another unfortunate reminder of humanity’s indelible signature on nature. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-have-no-idea-how-much-microplastic-is-in-australias-soil-but-it-could-be-a-lot-96858">We have no idea how much microplastic is in Australia's soil (but it could be a lot)</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/209487/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Hamilton receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Deniz Özkundakci received funding from the Bay of Plenty Regional Council. He also holds the Toihuarewa Waimāori - Bay of Plenty Regional Council Chair in Lake and Freshwater Science
</span></em></p><p class="fine-print"><em><span>Mohammadhassan Ranjbar receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Justin Brookes 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>Researchers even found textile fibres in very remote lakes with limited human presence.David Hamilton, Director, Australian Rivers Institute, Griffith UniversityDeniz Özkundakci, Associate Professor of Lake and Freshwater Science, University of WaikatoJustin Brookes, Director, Water Research Centre, University of AdelaideMohammad Hassan Ranjbar, Research Fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034922023-05-03T12:07:00Z2023-05-03T12:07:00ZHeading to a beach this summer? Here’s how to keep harmful algae blooms from spoiling your trip<figure><img src="https://images.theconversation.com/files/523475/original/file-20230428-22-cp3c0a.jpg?ixlib=rb-1.1.0&rect=35%2C0%2C5862%2C3926&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warning sign at Lido Key Beach in Sarasota, Fla., March 15, 2023, during a toxic algae bloom.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sign-warning-of-the-red-tide-risk-is-displayed-at-lido-key-news-photo/1248835855"> Jesus Olarte/AFP via Getty Images</a></span></figcaption></figure><p>Plunging into the ocean or a lake is one of the great joys of summer. But arriving at the beach to find water that’s green, red or brown, and possibly foul-smelling, can instantly spoil the party.</p>
<p>As a <a href="https://www.researchgate.net/profile/Brad-Reisfeld">toxicologist</a>, I study health risks from both synthetic and natural substances. I’ve conducted research into <a href="https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract_id/11137/report/0">early detection of harmful algal blooms</a>, or HABs, which are an increasing threat to humans, animals and the environment. </p>
<p>Toxins produced during these blooms have been implicated in human and animal illnesses in at least 43 states. Scientists have estimated that in the U.S. alone, freshwater HABs cause more than <a href="https://meetings.pices.int/publications/other/members/HAB-PolicyMakers.pdf">US$4.6 billion in damage yearly</a>. Here’s what to know about them if you’re bound for the water’s edge this summer.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/KfbM32b50fY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Harmful algal blooms have become a regular occurrence along large stretches of Florida’s coast in recent years.</span></figcaption>
</figure>
<h2>Tiny organisms, big impacts</h2>
<p>Algae and cyanobacteria – often called blue-green algae – are simple, plantlike organisms that live in water. They can grow out of control, or “bloom,” especially when the water is warm and slow moving. Climate change is <a href="https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/">making water bodies warmer</a>, increasing the risk of HABs. </p>
<p>The other major factor that drives blooms is high levels of nutrients like nitrogen and phosphorus, which fertilize algae. <a href="https://www.epa.gov/sites/default/files/2015-03/documents/facts_about_nutrient_pollution_what_is_hypoxia.pdf">Nutrient pollution</a> comes mainly from agriculture, wastewater treatment plants, septic systems and fossil fuel combustion.</p>
<p>Sometimes these blooms contain organisms that produce toxins – an umbrella term for many poisonous substances that <a href="https://medlineplus.gov/ency/article/002331.htm">come from animals or plants</a> and can make people and animals sick and adversely affect the environment. These events are called harmful algal blooms. </p>
<p>HABs occur <a href="https://hab.whoi.edu/maps/regions-us-distribution/">throughout the U.S.</a> and <a href="https://hab.whoi.edu/maps/regions-world-distribution/">worldwide</a>, in both saltwater and freshwater environments. They pose significant health risks to human, pets, livestock and wildlife; damage ecosystems; increase water treatment costs; restrict recreational activities; and cut into economic revenues.</p>
<p>People and animals can be exposed to HAB toxins through many routes. These include skin contact during activities such as swimming or boating; inhaling airborne droplets that contain toxins; swallowing contaminated water; or eating food or supplements that contain toxins. The most severe effects generally result from <a href="https://hab.whoi.edu/impacts/impacts-human-health/">consuming contaminated seafood</a>.</p>
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<h2>An array of toxins</h2>
<p>There are numerous <a href="https://www.cdc.gov/habs/pdf/ohhabs-algae-algal-toxins-and-other-pathogens-lists.pdf">HAB toxins</a>, including substances such as microcystin, saxitoxin, cylindrospermopsin, anatoxin-A and domoic acid. Each has a different action on the body, so HABs can have <a href="https://mywaterquality.ca.gov/habs/resources/docs/humanhealth/hab_physician_guide_may2020.pdf">diverse harmful effects</a>.</p>
<p>Typical <a href="https://www.cdc.gov/habs/illness.html">symptoms of illness</a> from exposure to HAB toxins can include stomach pain, vomiting or diarrhea; headache, fever, tiredness or other general symptoms; skin, eye, nose or throat irritation; and neurological symptoms such as muscle weakness or dizziness. Depending on the toxin, higher levels of exposure can result in tremors or seizures, respiratory distress, kidney toxicity, liver toxicity and even death.</p>
<p>As with many environmental exposures, children and older people may be especially sensitive to HAB toxins. People who regularly consume seafood caught in HAB-prone areas are also at risk of long-term health effects from potentially frequent, low-level exposures to HAB toxins.</p>
<h2>Recognizing and responding to HABs</h2>
<p>It’s not possible to tell whether a bloom is harmful just by looking at it, but there are some warning signs. If the water appears green, red, brown or yellowish in color; has a strong musty or fishy odor; has foam, scum, algal mats or paintlike streaks on the surface; or if there are dead fish or other marine life in the water or washed up on the shoreline, it’s likely that a HAB may be occurring.</p>
<p>If you are unsure whether a bloom is harmful or not, contact your local health department or environmental agency for guidance. As a general rule, it’s good to check with local agencies to see whether there are any relevant warnings when you go to the beach. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Cqv2IclhKUm/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>If you are notified of a bloom in a nearby body of water or in your public drinking water supply, the most important thing you can do to reduce your chances of getting sick is to follow local or state guidance. If you see signs of a bloom, stay out of the water and keep your pets out of the water.</p>
<p>It’s also important to follow local guidelines about consuming seafood caught through recreational fishing. It’s important to be aware that cooking contaminated seafood or boiling contaminated water <a href="https://www.webmd.com/food-recipes/food-poisoning/red-tide">does not destroy the toxins</a>. </p>
<h2>Be informed</h2>
<p>The U.S. Centers for Disease Control and Prevention provides <a href="https://www.cdc.gov/habs/general.html">resources and recommendations</a> related to HABs and ways to stay safe. Pet owners should also learn <a href="https://www.dec.ny.gov/docs/water_pdf/habspets.pdf">how to protect their dogs from HABs</a>. </p>
<p>Other federal agencies that offer information about HABs include <a href="https://hab.whoi.edu/">the U.S. National Office for Harmful Algal Blooms</a> and the <a href="https://www.niehs.nih.gov/health/topics/agents/algal-blooms/index.cfm">National Institute of Environmental Health Sciences</a>.</p>
<p>Many states conduct <a href="https://www.epa.gov/cyanohabs/state-habs-monitoring-programs-and-resources">HAB monitoring programs</a>, especially in areas that are known to be vulnerable to blooms, such as <a href="https://ohioseagrant.osu.edu/products/1h6jc/what-are-habs">western Lake Erie</a>. The U.S. Environmental Protection Agency offers <a href="https://www.epa.gov/cyanohabs/state-habs-resources">HAB resources by state</a>. Apps used by water quality managers and state officials who make management decisions about public water supply safety, including <a href="https://play.google.com/store/apps/details?id=com.topcoder.epa">CyAN Android</a> and <a href="https://qed.epa.gov/cyanweb/">CyANWeb</a>, may contain useful information about HABs in your area.</p>
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<h2>What’s being done about HABs?</h2>
<p>Many efforts are underway to prevent, control and mitigate HABs and provide early warnings to water system managers and health officials. </p>
<p>One example in the U.S. is the
<a href="https://www.epa.gov/water-research/cyanobacteria-assessment-network-cyan">Cyanobacteria Assessment Network, or CyAN</a>, a collaborative effort across several government agencies to develop an early warning indicator system to detect algal blooms in freshwater systems. There are also several ongoing projects for <a href="https://coastalscience.noaa.gov/science-areas/habs/hab-forecasts/">HAB forecasting by region</a>.</p>
<p>At the global scale, the <a href="https://data.hais.ioc-unesco.org/">Harmful Algal Information System</a> will eventually include harmful algal events and information from harmful algae monitoring and management systems worldwide.</p>
<p>Citizen scientists can provide invaluable help by monitoring local waters. If you would like to participate, consider joining the <a href="https://coastalscience.noaa.gov/monitoring-and-assessments/pmn/">Phytoplankton Monitoring Network</a> or <a href="https://cyanos.org/bloomwatch/">the Cyanobacteria Monitoring Collaborative</a>, and download and use the
<a href="https://cyanos.org/bloomwatch/">Cyanobacterial bloom app</a> to report potential HABs in bodies of water you visit.</p><img src="https://counter.theconversation.com/content/203492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brad Reisfeld received funding from the US Environmental Protection Agency to work on a project related to HABs detection</span></em></p>The tiny organisms that cause harmful blooms of algae can have a big impact on your trip to the shore. A toxicologist explains what causes these events and how to keep people and pets safe.Brad Reisfeld, Professor of Chemical and Biological Engineering, Biomedical Engineering, and Public Health, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2022852023-03-22T15:07:53Z2023-03-22T15:07:53ZFreshwater ecosystems are becoming increasingly salty. Here’s why this is a concern<figure><img src="https://images.theconversation.com/files/516784/original/file-20230321-502-l9q2xx.jpeg?ixlib=rb-1.1.0&rect=17%2C28%2C3844%2C2860&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Roads require de-icing strategies in northern regions, but this practice has negative effects on aquatic biodiversity.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Freshwater ecosystems around the world <a href="https://doi.org/10.1126/science.aad3488">are becoming saltier and saltier</a>. Many human-driven factors contribute to freshwater salinization, including: irrigation, oil extraction, <a href="https://ici.radio-canada.ca/nouvelle/1287569/mine-potasse-saskatchewan-sedley-environnement-pollution">potash mining</a>, and <a href="https://theconversation.com/laccumulation-des-sels-de-deglacage-dans-les-lacs-menace-ceux-qui-y-vivent-179166">road de-icing</a>. </p>
<p>As a result, salts enter waterways. But as bad news never comes alone, the salts are often accompanied by a toxic cocktail of other pollutants, whose combined toxicological effects are <a href="https://doi.org/10.1073/pnas.1711234115">largely unknown</a>.</p>
<p>Although the problem of rising freshwater salinization went largely unaddressed <a href="https://doi.org/10.1007/978-94-017-2934-5_30">for many decades</a>, it has gained considerable attention<a href="https://doi.org/10.1073/pnas.0507389102"> during the last 20 years</a>. </p>
<p>Scientists around the world are working together to understand the ecological impacts of increasing salinization on aquatic biodiversity and food webs. Our ultimate goal? To examine the adequacy of water quality toxicity thresholds for the protection of aquatic life. </p>
<h2>Salinization, a major problem</h2>
<p>Canada is home to a majority of the world’s freshwater resources, mostly concentrated in the provinces <a href="https://doi.org/10.1038/ncomms13603">of Ontario and Québec</a>, where close to 5 million tons of road salt are applied annually <a href="https://www.canada.ca/en/environment-climate-change/services/pollutants/road-salts/code-practice-environmental-management.html">to de-ice roads</a>. </p>
<p>Combined with climate change and increasing frequency and duration of drought in many regions of the world, <a href="https://doi.org/10.1038/nclimate1633">the problem is getting worse</a>. This is a major concern. Why? Because the availability of freshwater resources will become a critical factor for humanity <a href="https://doi.org/10.1073/pnas.1011615108">over the next 50 years</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=380&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=380&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=380&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The inequitable global distribution of surface freshwater resource availability. (Source: Philippe Rekacewicz, February 2006).</span>
</figcaption>
</figure>
<h2>Researchers from around the world mobilized</h2>
<p>We recently presented a series of articles in a special issue on freshwater salinization in the journal <em>Limnology and Oceanography Letters</em>, <a href="https://doi.org/10.1002/lol2.10307">published last February</a>. </p>
<p>In this special issue, we focus on sodium chloride (NaCl), the same molecule found in table salt, as a key agent of freshwater salinization. We highlight a series of co-ordinated field experiments, conducted by researchers in North America and Europe, that have addressed the impacts of freshwater salinization on <a href="https://www.thecanadianencyclopedia.ca/fr/article/zooplancton">zooplankton</a> (microscopic crustaceans) at a regional scale.</p>
<p>Zooplankton are an ecologically critical group in aquatic food webs and are often used as indicators to detect environmental change due to their sensitive ecological tolerances. </p>
<p>The main conclusions of these experiments are as follows:</p>
<ul>
<li>Water quality guidelines in Canada and the United States (standards) do not adequately protect freshwater zooplankton, which could lead to <a href="https://doi.org/10.1073/pnas.2115033119">an increase in the abundance of algae</a>, which the zooplankton feed on. This is because when zooplankton abundance decreases, especially for large grazers such as Daphnia, phytoplankton can proliferate under conditions of reduced predation; </li>
<li>Salinization of freshwater systematically leads to a loss of abundance and diversity of zooplankton <a href="https://doi.org/10.1002/lol2.10239">in all regions</a>; and </li>
<li>Individuals of the same zooplankton species do not all exhibit the same tolerance to salinity. Thus, this variation may interfere with our ability to predict community-level responses. Water quality guidelines may therefore need to be adjusted to become <a href="https://doi.org/10.1002/lol2.10277">more region-specific</a>.</li>
</ul>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.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">Regional coverage of a co-ordinated field mesocosm experiment (Hintz et al. 2022b, Hébert et al. 2022; Arnott et al. 2022), with an example of one of the experiments that was conducted at Lac Croche (Québec, Canada) (Astorg et al. 2022) (Figure modified from Hintz et al. 2022b).</span>
</figcaption>
</figure>
<h2>A matter of regulation</h2>
<p>Many questions remain unanswered. However, what we do now know is that long-term water quality guidelines (Canada: 120 mg Cl⁻¹L⁻¹; United States: 230 mg Cl⁻¹L⁻¹) and in the short term (Canada: 640 mg Cl⁻¹L⁻¹; United States: 860 mg Cl⁻¹L⁻¹) for chloride concentrations are too high to protect aquatic life <a href="https://doi.org/10.1021/acs.est.0c02396">in Canada and in the United States</a>. For reference, a pinch of salt in a pot of water corresponds to approximately 0.3 mg of Cl⁻¹/L⁻¹. In other words, adverse effects are observed at much lower concentrations. Regulations in Canada and the United States should therefore be reviewed. In Europe, the water quality standards for salinity <a href="https://doi.org/10.1098/rstb.2018.0019">for the protection of aquatic life in freshwater ecosystems are mostly absent</a>. </p>
<h2>The importance of taking concrete action</h2>
<p>Water quality guidelines for the protection of aquatic life are generally established using laboratory tests (called toxicological tests) <a href="https://doi.org/10.1002/lol2.10208">on a single species</a>. </p>
<p>However, aquatic habitats harbour a complex array of predators, prey, competitors, and pathogens, the interactions of which can limit our ability to <a href="https://doi.org/10.1016/j.scitotenv.2013.01.066">predict the responses of communities and species to pollutants </a>. </p>
<p>Thus, the collective research published in this special issue also highlights the importance of understanding ecological responses in multi-species communities in natural settings to assess <a href="https://doi.org/10.1073/pnas.2115033119">the responses of freshwater life to human impacts</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Aerial view of a field enclosure experiment conducted in a chloride-sensitive lake in the Laurentians (Québec) (Astorg et al. 2022) (Photo credit: Étienne Laliberté).</span>
</figcaption>
</figure>
<p>Overall, we should develop alternative applications and technologies that are <a href="https://doi.org/10.1007/s11270-011-1064-6">more sustainable and efficient</a>.</p>
<p>We also need to establish <a href="https://doi.org/10.1098/rstb.2018.0019">more appropriate water quality guidelines</a> to improve controls on salts entering our freshwater environments to reduce adverse effects on aquatic life <a href="https://doi.org/10.1007/s10533-021-00784-w">and the quality of our freshwater resources</a>.</p><img src="https://counter.theconversation.com/content/202285/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Les auteurs ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'ont déclaré aucune autre affiliation que leur organisme de recherche.</span></em></p>Although it has been considerably less studied than other environmental problems, salinization presents major challenges for biodiversity in freshwater and coastal areas.Alison Derry, Professeure agrégée, Université du Québec à Montréal (UQAM)Miguel Cañedo-Argüelles, Profesor lector en Ecología, Universitat de BarcelonaStephanie J Melles, Associate Professor, Spatial Ecology, Toronto Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1985062023-01-29T19:08:28Z2023-01-29T19:08:28ZIt’s hot, and your local river looks enticing. But is too germy for swimming?<figure><img src="https://images.theconversation.com/files/506732/original/file-20230127-18-rcv50u.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C2594%2C1732&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dan Himbrechts/AAP</span></span></figcaption></figure><p>Swimming in rivers, creeks and lakes can be a fun way to cool off in summer. But contamination in natural waterways can pose a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6023190/">risk to human health</a>. </p>
<p>Waterborne pathogens can <a href="https://www.cdc.gov/healthywater/swimming/swimmers/rwi.html">cause</a> acute gastrointestinal illnesses such as diarrhea and vomiting. Other common illnesses include skin rashes, respiratory problems, and eye and ear infections.</p>
<p>Unfortunately, it can be hard to find out if a waterway in Australia is safe for recreation. By contrast, a comprehensive system in Aotearoa-New Zealand, called <a href="https://www.lawa.org.nz/explore-data/swimming/">Can I Swim Here?</a>, provides timely water quality information for 800 beach, river and lake sites.</p>
<p>We have investigated the benefits and barriers associated with opening up waterways for recreation. Unsurprisingly, ensuring a local swimming site is safe is key to getting people using it. That includes giving people access to accurate information about water quality.</p>
<figure class="align-center ">
<img alt="two women jump into waterway" src="https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506729/original/file-20230127-14-zug4v0.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">It can be hard to find out if a waterway in Australia is safe for swimming.</span>
<span class="attribution"><span class="source">Dan Himbrechts/AAP</span></span>
</figcaption>
</figure>
<h2>Can swimming really make you sick?</h2>
<p><a href="https://www.cdc.gov/healthywater/swimming/swimmers/rwi.html">Contaminated water</a> can exist in swimming pools and spas, as well as oceans, lakes, and rivers, exposing humans to a range of pathogens. </p>
<p>According to <a href="https://www.environment.nsw.gov.au/topics/water/beaches/is-it-safe-to-swim/what-are-the-health-risks-for-swimmers">official advice</a> in New South Wales, common waterborne pathogens include:</p>
<ul>
<li><p>enteric bacteria such as Escherichia coli (E.coli) or Enterococci, that live in the intestinal tracts of all warm-blooded animals and can enter water as faecal matter (or poo). They can cause gastroenteritis, skin and ear infections and dysentery</p></li>
<li><p>viruses such as noroviruses and hepatitis. They can cause diarrhoea, vomiting, hepatitis and respiratory disease</p></li>
<li><p>protozoa such as giardia which, once ingested, can live as parasites in humans and animals and cause diarrhoea.</p></li>
</ul>
<p>Australian <a href="https://academic.oup.com/aje/article/170/12/1469/157126?login=false">research</a> has documented a link between gastroeneritis and people swimming in public pools and freshwater sites such as rivers, lakes and dams. </p>
<p>Other water quality hazards for swimming include toxic <a href="https://www.health.vic.gov.au/water/health-effects-of-blue-green-algae">blue-green algae</a> and exposure to chemical pollutants.</p>
<p>Recent floods in Australia have led to an elevated risk of water contamination. As others have <a href="https://theconversation.com/travelling-around-australia-this-summer-heres-how-to-know-if-the-water-is-safe-to-drink-196294">noted</a>, flood waters can be <a href="https://www.epa.vic.gov.au/for-community/environmental-information/water/heavy-rainfall-events/how-to-manage-waste-after-a-flood/health-risks-from-flood-waters#:%7E:text=Floodwater%20is%20often%20contaminated%20by,and%20skin%20infections%2C%20and%20rashes">highly polluted</a> with disease-causing organisms, including from sewerage overflows.</p>
<p>So how do swimming locations get contaminated? Pollution can come from untreated sewage, or runoff containing animal poo or fertilisers. The <a href="https://www.weforum.org/agenda/2022/04/50-of-u-s-lakes-and-rivers-are-too-polluted-for-swimming-fishing-drinking">source could be</a> chemicals from nearby industrial activities, or the water users themselves.</p>
<p>Thankfully, most disease outbreaks from swimming are not fatal. An exception is the amoeba <a href="https://www.health.nsw.gov.au/Infectious/factsheets/Pages/naegleria-fowleri.aspx">Naegleria fowleri</a>. It lives in warmer waters and can cause amoebic meningitis, a potentially fatal brain disease.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-stunning-recovery-of-a-heavily-polluted-river-in-the-heart-of-the-blue-mountains-world-heritage-area-176246">The stunning recovery of a heavily polluted river in the heart of the Blue Mountains World Heritage area</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="Rubbish-strewn water with bird flying above" src="https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506731/original/file-20230127-18-lvaol7.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">Rain and flooding can cause pollutants to run into waterways.</span>
<span class="attribution"><span class="source">James Ross/AAP</span></span>
</figcaption>
</figure>
<h2>How safe is your local swimming hole?</h2>
<p>In Australia, guidance on recreational water quality tends to focus on ocean beaches. For example, NSW’s <a href="https://www.environment.nsw.gov.au/topics/water/beaches/beachwatch-water-quality-program">Beachwatch</a> program cover more than 200 NSW coastal (and some estuary) beaches. The advice is based on likelihood of rain combined with testing swimming sites for faecal bacteria. </p>
<p>The Victorian government also <a href="https://www.epa.vic.gov.au/for-community/summer-water-quality/water-quality-across-victoria">provides</a> coastal swimming guidance for 36 beaches in Port Phillip Bay.</p>
<p>But away from the coast, information on the water quality of our local rivers, creeks and lakes, is sparse. </p>
<p>In NSW, advice exists for swimming and boating at <a href="https://www.penrithcity.nsw.gov.au/waste-environment/environment/recreational-water-quality">four sites</a> on the Nepean River in Western Sydney. Information is provided for a recently reopened swimming site at <a href="https://www.cityofparramatta.nsw.gov.au/water-quality-lake-parramatta">Lake Parramatta</a> and for swimming at some <a href="https://www.bmcc.nsw.gov.au/waterquality#recwater">Blue Mountains sites</a>.</p>
<p>In Victoria, the <a href="https://www.epa.vic.gov.au/for-community/summer-water-quality/yarra-watch">Yarra Watch</a> program monitors four swimming sites in freshwater stretches of the Yarra River, upstream of Melbourne. </p>
<p>And authorities in Canberra <a href="https://www.theswimguide.org/beach/8445">provide</a> regular water quality monitoring and swimming <a href="https://www.cityservices.act.gov.au/news/news-and-events-items/water_quality_in_our_lakes_and_ponds#current_advice">advice</a> for lakes and rivers.</p>
<p>But in contrast to Australia, New Zealand provides far more detailed and broad guidance.</p>
<figure class="align-center ">
<img alt="people swimming in river" src="https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.jpg?ixlib=rb-1.1.0&rect=0%2C1952%2C7947%2C3534&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506725/original/file-20230127-25-c9kdxe.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">Authorities in Canberra provide regular water quality monitoring and swimming advice.</span>
<span class="attribution"><span class="source">Lukas Coch/AAP</span></span>
</figcaption>
</figure>
<h2>How New Zealand does it</h2>
<p>New Zealand’s world-leading national program <a href="https://www.lawa.org.nz/explore-data/swimming/">Can I swim here?</a> enables people to find the best places to swim across 800 beach, river and lake sites across the country. </p>
<p>The advice is provided by <a href="https://www.lawa.org.nz/about">LAWA</a> (Land, Air, Water Aotearoa), a collaboration between regional councils, the New Zealand government, scientific experts and academics, and a philanthropist organisation.</p>
<p>The data available includes both the latest weekly water quality test results, and results dating back five years.</p>
<p>The guidance also includes an <a href="https://www.lawa.org.nz/explore-data/swimming/">interactive map</a> (see below) where users can zoom to swimming sites in their region.</p>
<figure class="align-center ">
<img alt="map of NewZealand showing red, orange and green dots" src="https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=710&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=710&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=710&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=893&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=893&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506736/original/file-20230127-11-cprhoa.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=893&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The ‘Can I swim here?’ site features an interactive map.</span>
<span class="attribution"><span class="source">https://www.lawa.org.nz</span></span>
</figcaption>
</figure>
<h2>More work is needed</h2>
<p>Everyone loves to be around, on and in the water, especially during summer. As well as providing a way to cool down, local swimming holes are great places for people to socialise, exercise and engage with nature – especially for those not near a beach.</p>
<p>Governments are recognising the <a href="https://www.dpie.nsw.gov.au/premiers-priorities/great-public-spaces/open-space/open-spaces-program/places-to-swim">real opportunity</a> to open up underused waterways for recreation across Australia. But for the sake of our communities, more work is needed on improving water quality and sharing information. </p>
<p>Australia has a lot to learn from New Zealand and <a href="https://www.bern.com/en/aare-river/floating-favorite-routes">other countries</a> on how to manage our waterways for recreational use. And ongoing research, partnering with government and industry, is clearly needed.</p>
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Read more:
<a href="https://theconversation.com/travelling-around-australia-this-summer-heres-how-to-know-if-the-water-is-safe-to-drink-196294">Travelling around Australia this summer? Here's how to know if the water is safe to drink</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/198506/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian A Wright has received funding from industry, as well as Commonwealth, NSW and local governments. He formerly worked for Sydney Water Corporation.</span></em></p><p class="fine-print"><em><span>Nicky Morrison has received funding from industry, as well as NSW and local governments.</span></em></p>Ensuring a swimming site is safe is key to getting people using it. That means giving people timely information about water quality.Ian A. Wright, Associate Professor in Environmental Science, Western Sydney UniversityNicky Morrison, Professor of Planning and Director of Urban Transformations Research Centre, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1894812022-08-26T14:43:01Z2022-08-26T14:43:01ZExtensive algal blooms in England’s lakes: here’s why<figure><img src="https://images.theconversation.com/files/481306/original/file-20220826-1650-8ddjov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There have been reports of extensive blooms of blue-green algae on Lake Windermere this summer.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fishing-boat-on-green-water-aerial-1804469569">Sergey Muhlynin/Shutterstock</a></span></figcaption></figure><p>This year has seen growing public concern over the state of England’s largest lake, Windermere. Campaigners, local residents and visitors have <a href="https://www.theguardian.com/uk-news/2022/aug/24/it-stinks-lake-windermere-plagued-by-blue-green-algae-as-toxic-as-cobra-venom">reported</a> extensive blooms of blue-green algae at the site, with concern for its impact on health and ecology.</p>
<p>Somewhat misleadingly, blue-green algae are not actually algae. They are a type of bacteria, called cyanobacteria, which use sunlight to obtain energy and grow. There are many species of cyanobacteria. These can grow as single cells, too small to be seen with the naked eye, or in large clusters.</p>
<p>Cyanobacterial blooms are not new. They originated approximately <a href="https://news.mit.edu/2021/photosynthesis-evolution-origins-0928">3 billion years ago</a> and, through photosynthesis, they oxygenated the Earth’s atmosphere – helping to make other life possible. Cyanobacteria are found in a wide variety of freshwater habitats worldwide, including lakes such as Windermere.</p>
<p>The nutrients in wastewater, such as phosphorus, are critical for the formation of cyanobacterial blooms. The UK Centre for Ecology & Hydrology and the Freshwater Biological Association have carried out <a href="https://uk-scape.ceh.ac.uk/our-science/projects/cumbrian-lakes-monitoring-platform">long-term monitoring</a> of the lake. These data show that Windermere frequently experienced blooms in the past. </p>
<h2>What causes a cyanobacterial bloom?</h2>
<p>Blooms occur when cyanobacteria, usually present at low concentrations, multiply rapidly. This process is often invisible to lake users. However, during calm weather conditions, the cyanobacteria float to the surface and accumulate along the shoreline, where they are visible as “scums” or “slicks”. </p>
<p>High nutrient concentrations are needed to support large amounts of cyanobacteria. In Windermere, waste treatment sites combined with sewer overflows, run-off from nearby farmland and release from lake sediments can leak phosphorus into the lake.</p>
<figure class="align-center ">
<img alt="A sewer outflow discharging water into a river." src="https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481316/original/file-20220826-16-ij15fr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sewer overflows can leak phosphorus into the lake, fuelling cyanobacterial blooms.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/discharge-untreated-water-into-natural-lake-1630211617">Slavik Rostovski/Shutterstock</a></span>
</figcaption>
</figure>
<p>Nitrogen concentrations can be important too. Some cyanobacteria can use dissolved nitrogen gas from the air to fuel their growth. This can give them a competitive advantage over other algae when nitrate concentrations are low.</p>
<p>Windermere is also <a href="https://www.ceh.ac.uk/news-and-media/blogs/lakes-hot-water-warming-trend-revealed-eight-decades-cumbrian-lake-temperature">warming</a> rapidly. The lake’s mean surface water temperature has risen by 1.7°C over the past 70 years, while warm summer conditions this year have contributed to <a href="https://seatemperature.info/windermere-water-temperature.html">above average</a> water temperatures for August. Fuelled by increasing nutrient concentrations, these warmer conditions have stimulated a rapid increase in cyanobacteria in Windermere.</p>
<p>As the climate continues to change, we can expect these weather conditions to become more frequent, and the risk of cyanobacterial blooms to increase.</p>
<h2>Are these blooms harmful?</h2>
<p>Cyanobacteria can produce potent toxins that can cause illness in humans and be fatal for animals.</p>
<p>However, not all blooms are toxic. This depends on both the species of cyanobacteria and the environmental conditions at the time. It is impossible to tell which blooms are toxic by sight and this can only be confirmed by laboratory analysis.</p>
<p>In addition to toxicity, the decomposition of dead cells from large blooms can reduce the oxygen content of the water. While this can reduce the habitat quality for aquatic wildlife, it can also <a href="https://ciglr.seas.umich.edu/spring-2021-e-newsletter/spotlight-dead-zone-sediment-p-release/">alter</a> the chemistry of the water and lake sediments. The reduction in oxygen concentration causes phosphorus that has been bound to iron in sediment to be released, which may stimulate further cyanobacterial growth.</p>
<h2>Can we reduce levels of harmful algae?</h2>
<p>To reduce the incidence of harmful blooms in lakes, the extreme weather conditions caused by climate change must be addressed. Mitigation of climate change can only come from coordinated international policy and action.</p>
<p>Locally, it is more feasible to manage the discharge of nutrients into lakes. However, both their source and pathway to the lake need to be established. </p>
<p>Further scientific evidence is required to determine what level of nutrient reduction is possible, and to guide measures to reduce the most significant sources. The Environment Agency has spent <a href="https://www.bbc.co.uk/news/uk-england-cumbria-62560942">more than £700,000</a> over the past decade on tackling cyanobacterial blooms.</p>
<p>Another challenge lies in forecasting how lakes will respond to differing future climate change scenarios. We cannot necessarily return lakes such as Windermere to a pristine state because the climate, human activities, land use in the surrounding area and species populations at the lake have all changed.</p>
<p>The sustainable management of our ecosystems for people and nature will require further research to forecast what the future of our freshwater ecosystems could be if we act now and, crucially, what will happen if we fail to do so.</p><img src="https://counter.theconversation.com/content/189481/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Thackeray receives no personal funding, but UKCEH long-term research at Windermere and other lakes is funded by Natural Environment Research Council award number NE/R016429/1 as part of the UK-SCAPE programme delivering National Capability.</span></em></p>Windermere has seen extensive algal blooms, attracting attention over its ecological consequences. But this is nothing new.Stephen Thackeray, Lake Ecologist and Modeller, UK Centre for Ecology & HydrologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1883442022-08-09T15:03:58Z2022-08-09T15:03:58ZDo chemicals in sunscreens threaten aquatic life? A new report says a thorough assessment is ‘urgently needed,’ while also calling sunscreens essential protection against skin cancer<figure><img src="https://images.theconversation.com/files/478144/original/file-20220808-4922-ds99rt.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3794%2C2514&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sunscreens for sale at a Walgreens drug store.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/shelves-of-suntan-lotion-for-sale-in-walgreens-news-photo/665553846">Jeff Greenberg/Universal Images Group via Getty Images</a></span></figcaption></figure><p><em>Studies have shown that the same active ingredients in sunscreens that protect people from cancer-causing ultraviolet rays can be toxic to a range of species in oceans, rivers and lakes. With both of these risks in mind, a <a href="https://nap.nationalacademies.org/catalog/26381/review-of-fate-exposure-and-effects-of-sunscreens-in-aquatic-environments-and-implications-for-sunscreen-usage-and-human-health">new report</a> from the National Academies of Sciences, Engineering and Medicine finds an urgent need for more information about whether these chemicals threaten aquatic life on a broad scale.</em> </p>
<p><em>The report calls on the U.S. Environmental Protection Agency to conduct a detailed review called an <a href="https://www.epa.gov/risk/ecological-risk-assessment">environmental risk assessment</a> of the likelihood that exposure to one or more of these chemicals, called <a href="https://ntp.niehs.nih.gov/whatwestudy/topics/uvfilters/index.html">UV filters</a>, may harm organisms in saltwater and freshwater ecosystems. The study recommends focusing on two types of settings – coral reefs in shallow waters near shore, and slow-moving freshwater bodies like ponds and marshes – that are heavily used for recreation and/or exposed to wastewater or urban runoff.</em> </p>
<p><em>The study recognizes that sunscreen with a Sun Protection Factor (SPF) of 30 or higher is an effective defense against sunburn and skin cancer, and that making it harder to buy broad-spectrum sunscreen that people will actually use could harm public health. Accordingly, it calls for research examining how changes in sunscreen usage could affect human health. Two members of the study committee explain how their group balanced these concerns.</em></p>
<h2>Many species are exposed to many stresses</h2>
<p><strong>Robert Richmond, Research Professor and Director, Kewalo Marine Laboratory, University of Hawaii at Manoa</strong></p>
<p>Studies to date have provided compelling laboratory evidence that some UV filters can have toxic effects on aquatic species, including <a href="http://dx.doi.org/10.1126/science.abo4627">corals</a>, <a href="http://dx.doi.org/10.1126/science.abn2600">anemones</a> and <a href="https://doi.org/10.1021/acs.est.8b02418">zebrafish</a>, that are exposed to the chemicals. These findings have raised concerns about sunscreens’ <a href="https://doi.org/10.1016/j.envpol.2020.115894">larger-scale impacts on biological communities and ecosystems</a>.</p>
<p>But outcomes in the environment will differ depending on what compounds, ecosystems and local environmental conditions are involved. That’s especially true for coral reefs. The committee highlighted reefs because they are <a href="https://coast.noaa.gov/states/fast-facts/coral-reefs.html">ecologically, economically and culturally valuable</a>, and attract large numbers of tourists who use sunscreens. </p>
<p>Coral reefs are <a href="https://doi.org/10.1016/j.oneear.2021.08.016">declining worldwide</a> due to multiple human-induced disturbances. Some of these disturbances are global, such as <a href="https://oceanservice.noaa.gov/facts/coralreef-climate.html">ocean warming and acidification driven by climate change</a>. Other stressors, such as coastal water quality, are more local. </p>
<p>Studying the effects of chemicals on corals and coral reefs is challenging because they are both complex systems. Reef-building corals are a combination of an animal, single-celled algae and rich populations of bacteria living and working together. Coral reefs are made up of thousands of interacting organisms. </p>
<p>Importantly, many stress responses in corals occur without causing outright death, but impair their health, growth, resilience and even ability to reproduce. Scientists need to know more about these responses to guide effective management responses and interventions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dozens of parrotfish swim over a reef of res, white and yellow corals." src="https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478146/original/file-20220808-14-54tuwr.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">Healthy coral reefs like this one in American Samoa support such diverse communities of fish and other organisms that they often are called the rainforests of the sea.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1016/j.oneear.2021.08.016">Kevin Lino, NOAA/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>After in-depth reviews of the existing data, our study committee recommended that the U.S. Environmental Protection Agency should undertake an ecological risk assessment of the 17 UV filters used in sunscreens sold in the U.S. Such a study would include a comparison of toxicity findings to relevant concentrations and exposure conditions. </p>
<p>For example, what happens to organisms exposed to these chemicals occasionally versus those exposed regularly, in calm bays or along open, wave-swept coasts? How do UV filters differ in whether they break down in water, or accumulate in sediments or the tissues of living organisms? </p>
<p>In our view, an ecological risk assessment would provide EPA and others the basis for sound and effective policy development. The sooner this happens and the results are applied to the regulatory process, the better for everyone who is affected, including future generations.</p>
<h2>The challenge of understanding long-term effects on humans and the environment</h2>
<p><strong>Karen Glanz, George A. Weiss University Professor and Director, UPenn Prevention Research Center, University of Pennsylvania</strong></p>
<p>The question of whether UV filters pose harm to the environment while helping to reduce skin damage and prevent skin cancer is a conundrum. It seemingly pits human and environmental health against each other head-to-head and asks policymakers, medical experts and the public to choose between them. </p>
<p>Humans need sunlight to live, but overexposure to the sun’s damaging rays – ultraviolet radiation – causes sunburn and wrinkles and is a risk factor for the development of skin cancers, including the most deadly type, <a href="https://www.cancer.org/cancer/melanoma-skin-cancer/about/what-is-melanoma.html">melanoma</a>. Routine use of <a href="https://www.aad.org/public/diseases/skin-cancer/prevent/how">broad-spectrum sunscreen with SPF 30+</a> when outdoors has been found to prevent skin damage and skin cancer. But sunscreens are most effective as part of a <a href="https://www.cdc.gov/cancer/skin/basic_info/sun-safety.htm">set of behaviors</a> that also includes wearing hats and cover-up clothing and seeking shade. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"616291967698386944"}"></div></p>
<p>Most people in the U.S. don’t practice these behaviors frequently or thoroughly enough. So it’s important to weigh very carefully the potential effects of restricting the choice of available sunscreens. </p>
<p>Some jurisdictions already restrict the sale of certain sunscreens because concerned advocates believe doing so will be good for the environment. In the U.S., they include <a href="https://www.cntraveler.com/story/these-destinations-are-banning-certain-sunscreens">Hawaii, the U.S Virgin Islands and the city of Key West, Florida</a>. Our report doesn’t draw a definitive conclusion about whether these measures are scientifically justified or effective. Rather, it emphasizes analyzing whether and how they may affect human health as well as the
environment.</p>
<p>The study draws attention to the challenge of understanding risks from UV filters to aquatic environments under various conditions, and in the context of overarching environmental stressors such as rising sea temperatures. It’s important to understand that for both environmental and human health issues, laboratory studies don’t always match what happens in the environment. </p>
<p>Studies of model systems such as bacteria and yeast, and organisms such as fish embryos and insect larvae, can yield findings that do not hold up in studies of humans. For both the environment and humans, it may not be possible or ethical to conduct true experiments that test the long-term effects of chemicals in UV filters. </p>
<p>Members of our committee wrestled to interpret the available evidence, and also with the gaps in that evidence. Ultimately we concluded that the science is not settled, but that there is much to build on to advance understanding of this issue. Our conclusions are not a win/lose outcome for either the environment or humans. Rather, they point to a need to think both broadly and strategically for the benefit of people and the planet.</p><img src="https://counter.theconversation.com/content/188344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Richmond receives funding from the National Science Foundation, the National Oceanic and Atmospheric Administration, the U.S. Fish and Wildlife Service, the Pew Environmental Group, the National Fish and Wildlife Foundation, the H.W. Hoover Foundation and the Hawaii Division of Aquatic Resources.
He has been a Pew Fellow in Marine Conservation, and an Aldo Leopold Fellow in Environmental Leadership, and has served on the Board of Directors of the Palau International Coral Reef Center and as Science Advisor to the All Islands Committee of the US Coral Reef Task Force. He was a member of a previous study committee organized by the National Academies, on Interventions to Increase the Resilience of Coral Reefs.
</span></em></p><p class="fine-print"><em><span>Karen Glanz conducts research cancer prevention and control, theories of health behavior, and social and health policy. She has conducted descriptive, observational, methodological, intervention, and dissemination research in skin cancer prevention since 1993. She has worked on analyses of national surveys of UV exposure and sun protection; developed, analyzed and validated measures and methods of skin cancer prevention research; and led evidence reviews for skin cancer prevention. Her research has been funded by the U.S. Centers for Disease Control and Prevention, the National Institutes of Health, and the Skin Cancer Foundation. Dr. Glanz served on the US Task Force on Community Preventive Services for 10 years and co-led reviews of the effectiveness of skin cancer prevention programs. She is an elected member of the National Academy of Medicine. </span></em></p>Rising concern about possible environmental damage from the active ingredients in sunscreens could have ripple effects on public health if it causes people to use less of them.Robert Richmond, Professor of Biology and Director, Kewalo Marine Laboratory, University of HawaiiKaren Glanz, George A. Weiss University Professor and Director, UPenn Prevention Research Center, University of PennsylvaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1852862022-07-19T12:26:19Z2022-07-19T12:26:19ZThe westward spread of zebra and quagga mussels shows how tiny invaders can cause big problems<figure><img src="https://images.theconversation.com/files/474702/original/file-20220718-76232-pd2800.jpg?ixlib=rb-1.1.0&rect=17%2C5%2C3848%2C2579&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A boat propeller encrusted with zebra mussels.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/28LifoX">NPS/Flickr</a></span></figcaption></figure><p>The <a href="https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=5">zebra mussel</a> has been a poster child for invasive species ever since it unleashed economic and ecological havoc on the <a href="https://www.greatlakesnow.org/2020/02/zebra-mussels-impact-good-bad/">Great Lakes</a> in the late 1980s. Yet despite intensive efforts to control it and its relative, the <a href="https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=95">quagga mussel</a>, these fingernail-sized mollusks are <a href="https://nas.er.usgs.gov/UserImages/current_zm_quag_map.jpg">spreading through U.S. rivers, lakes and bays</a>, clogging water supply pipes and altering food webs. </p>
<p>Now, the mussels threaten to reach the country’s last major uninfested freshwater zones to the west and north: the <a href="https://civileats.com/2022/05/17/zebra-mussels/">Columbia River Basin</a> in Washington and Oregon, and the waterways of <a href="https://www.alaskasnewssource.com/2022/06/18/invasive-species-awareness-week-puts-focus-zebra-mussel-prevention-alaska/">Alaska</a>.</p>
<p>As an <a href="https://www.researchgate.net/scientific-contributions/Christine-Keiner-2071802254">environmental historian</a>, I study how people’s attitudes toward <a href="https://ugapress.org/book/9780820337180/the-oyster-question/">nonindigenous</a> <a href="https://ugapress.org/book/9780820338958/deep-cut/">species</a> have changed over time. Like many other aquatic aliens, zebra and quagga mussels spread to new bodies of water when people move them, either accidentally or deliberately. Human-built structures, such as canals, and <a href="https://theconversation.com/how-the-japanese-tsunami-sent-marine-invaders-across-the-ocean-and-why-you-should-be-worried-53107">debris</a> can also help invaders bypass natural barriers. </p>
<p>In my view, reducing the damage from these outbreaks – and preventing them if possible – requires understanding that human activities are the root cause of costly biological invasions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing zebra and quagga mussel distribution in 2021." src="https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474711/original/file-20220718-24-6taz30.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Zebra and quagga mussels have moved east, south and west from the Great Lakes into many other U.S. rivers and lakes.</span>
<span class="attribution"><a class="source" href="https://nas.er.usgs.gov/UserImages/current_zm_quag_map.pdf">USGS</a></span>
</figcaption>
</figure>
<h2>Past transoceanic invasions</h2>
<p>European exploration of the Americas between the late 1400s and 1700s led to massive transfers of organisms, a process known as the <a href="https://www.smithsonianmag.com/history/alfred-w-crosby-on-the-columbian-exchange-98116477/">Columbian exchange</a>, named for Christopher Columbus. Many investors grew rich through shipping livestock and plantation crops across the oceans. Transatlantic travel also introduced microbes that caused infectious diseases, such as smallpox and measles, that <a href="https://doi.org/10.1097/00000441-200204000-00009">killed millions of Native Americans</a> who lacked immunity. </p>
<p>During the 19th century, European and North American colonizers established <a href="https://theconversation.com/victorian-efforts-to-export-animals-to-new-worlds-failed-mostly-126003">acclimatization societies</a> to import desired species of foreign animals and plants to use for food, sport hunting or beautifying their environments. Many such efforts failed when the introduced species could not adapt to their new conditions and died off. </p>
<p>Others triggered legendary ecological disasters. For example, after the Victorian Acclimatisation Society <a href="https://theconversation.com/the-rabbits-of-christmas-past-a-present-that-backfired-for-australia-35544">released European rabbits in Australia</a> in 1859, they multiplied rapidly. Feral rabbits and other introduced species like <a href="https://theconversation.com/this-critically-endangered-marsupial-survived-a-bushfire-then-along-came-the-feral-cats-185133">cats</a> have destroyed millions of Australia’s native plants and animals.</p>
<p>Shipping has also accidentally spread alien species. Human-built canals made it easier to transport goods, but also provided new <a href="https://link.springer.com/book/10.1007/978-1-4020-5047-3?noAccess=true">pathways for aquatic pests</a>. </p>
<p>During the late 19th and early 20th centuries, for example, Canada expanded the Welland Canal between Lake Ontario and Lake Erie to allow large ships to bypass Niagara Falls. By 1921, these technological improvements enabled the <a href="http://sealamprey.org/">sea lamprey</a>, a parasitic fish, to move from Lake Ontario into the upper Great Lakes, where it is still a serious <a href="https://www.michiganradio.org/environment-science/2019-10-24/after-70-years-the-fight-to-get-sea-lampreys-out-of-the-great-lakes-continues">threat to commercial fisheries</a>. </p>
<p>In 1959, the U.S. and Canada opened the <a href="https://muse.jhu.edu/book/6966">St. Lawrence Seaway</a>, a maritime network that connects the Atlantic with the Great Lakes. Ocean-going ships using the seaway brought along stowaway species in <a href="https://www.invasivespeciesinfo.gov/subject/ballast-water">ballast water</a> – tanks full of water, used to keep the ships stable at sea. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Water pours from an outlet on a large bulk carrier vessel's bow into the harbor." src="https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=395&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=395&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=395&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474707/original/file-20220718-76570-82v3j7.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">A ship berthed in Southampton, England, discharges ballast water.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/southampton-england-uk-a-bulk-carrier-alongside-berth-with-news-photo/1355165014">Peter Titmuss/UCG/Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<p>When ships reached their destinations and flushed out their ballast tanks, they released alien plants, crustaceans, worms, bacteria and other organisms into local waters. In a milestone 1985 study, Williams College biologist <a href="https://mystic.williams.edu/about/faculty/dr-james-t-carlton/">Jim Carlton</a> described how ballast water discharges provided a <a href="http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=7865531">powerful vehicle for biological invasions</a>. </p>
<h2>The Great Lakes mussel invasion</h2>
<p>Zebra mussels are native to the Black and Caspian Seas. They are thought to have entered North America in the <a href="https://doi.org/10.1016/S0380-1330(08)71617-4">early 1980s</a> and were formally identified in the Great Lakes in <a href="https://www.jsonline.com/in-depth/archives/2021/09/02/how-zebra-mussels-and-quagga-mussels-changed-great-lakes-forever/7832198002/">1988</a>, followed by quagga mussels in 1989. </p>
<p>Soon the striped bivalves were blanketing hard surfaces throughout the lakes and washing up on shorelines, cutting beachgoers’ feet. Zebra mussels clogged intake pipes at drinking water treatment plants, <a href="https://www.osti.gov/biblio/6368446-infestation-monroe-power-plant-zebra-mussel-dreissena-polymorpha">power stations</a>, <a href="https://seagrant.sunysb.edu/ais/pdfs/Firefacts-v3.pdf">fire hydrants</a> and <a href="https://www.nrc.gov/reading-rm/doc-collections/gen-comm/info-notices/1989/in89076.html">nuclear reactors</a>, dangerously reducing water pressure and requiring expensive remedies.</p>
<p>Mollusks are filter feeders that typically make water clearer. But zebra and quagga mussels filtered so much plankton from the water that they starved native mussels and fostered <a href="https://www.sciencedaily.com/releases/1998/09/980919115852.htm">harmful algal blooms</a>. The invaders also passed deadly <a href="https://www.mlive.com/chronicle/2007/12/avian_botulism_killing_birds.html">type E botulism</a> to fish-eating birds. </p>
<p>By the early 1990s, 139 alien species had become established in the Great Lakes, with almost one-third arriving after the St. Lawrence Seaway opened. Ship-related introductions, along with other pathways, such as aquaculture and aquarium and bait fish releases, transformed the Great Lakes into one of the world’s <a href="https://doi.org/10.1016/S0380-1330(93)71197-1">most invaded freshwater ecosystems</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YiFHlOiPn1M?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Local officials grapple with a spreading infestation of zebra mussels in Lake Brownwood in central Texas.</span></figcaption>
</figure>
<h2>Early policy responses</h2>
<p>The U.S. began <a href="https://www.fws.gov/law/nonindigenous-aquatic-nuisance-prevention-and-control-act-1990">regulating ballast water management in 1990</a> but had trouble closing loopholes. For instance, vessels declaring that they had no pumpable ballast water on board did not have to empty and refill their ballast tanks in the middle of a voyage with clean ocean water. As a result, live freshwater organisms lurking in tank sediments could still be released in vulnerable ports. </p>
<p>Finally, after <a href="https://glpf.org/funded-projects/assessment-of-transoceanic-nobob-vessels-and-low-salinity-ballast-water-as-vectors-for-nonindigenous-species-introductions-to-the-great-lakes/">comprehensive studies</a>, the U.S. and Canada in 2006 required ships to flush tanks containing residual sediment with seawater. A 2019 assessment found that <a href="https://doi.org/10.1016/j.jglr.2019.09.002">only three new species became established</a> in the Great Lakes from 2006-2018, none of them via ship ballast.</p>
<p>Now, however, other human activities are increasingly contributing to harmful freshwater introductions – and with shipping regulated, the main culprits are thousands of private boaters and anglers. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"832332632537055233"}"></div></p>
<h2>Stemming the westward spread</h2>
<p>Zebra and quagga mussels are moving west and south from the Great Lakes, attached to private boats or carried in bilge water and bait buckets. They have been found in <a href="https://doi.org/10.1111/j.1523-1739.2010.01490.x">Nevada</a>, <a href="https://news.asu.edu/20200910-arizona-impact-invasive-species-continues-flex-its-mussels-arizona%E2%80%99s-waterways">Arizona</a>, <a href="https://wildlife.ca.gov/Conservation/Invasives/Quagga-Mussels/Incident-Description">California</a>, <a href="https://www.deseret.com/2015/5/7/20564487/potential-mussel-infestation-threatens-water-supply-could-cost-state-millions">Utah</a>, <a href="https://www.koaa.com/news/covering-colorado/invasive-mussels-no-longer-present-in-colorado-cpw-says">Colorado</a> and <a href="https://www.hcn.org/issues/48.22/latest-invasive-zebra-mussels-have-reached-montana">Montana</a>.</p>
<p>If the mussels reach the Columbia River ecosystem, they will threaten native wildlife and irrigation pipelines and dams that are vital for agriculture and hydropower. Government officials, wildlife managers and scientists are working hard to prevent that from happening. </p>
<p>Public outreach is critical. Travelers who transport their boats without decontaminating them can transfer zebra and quagga mussels to inland rivers and lakes. The mussels can survive out of water in hot places for weeks, so it’s important for boaters and anglers to <a href="https://stdofthesea.utah.gov/">clean, drain and dry</a> boating equipment and fishing gear.</p>
<p>Aquarium keepers can help stem the tide by <a href="https://www.fws.gov/sites/default/files/documents/zebra-mussel-disposal.pdf">disinfecting tanks and accessories</a> in order to prevent accidental releases of live organisms into public waterways, and by being vigilant about their purchases. In 2021, zebra mussels were detected in imported moss balls sold as aquarium plants across the <a href="https://fws.gov/story/invasive-zebra-mussels-found-moss-balls">U.S.</a> and <a href="https://www.cbc.ca/news/canada/new-brunswick/zebra-mussles-invasive-species-1.5960252">Canada</a>. </p>
<p>The U.S. Geological Survey maintains a <a href="https://nas.er.usgs.gov/SightingReport.aspx">website</a> where people can report sightings of nonindigenous aquatic species, potentially spotting new infestations during the <a href="https://edis.ifas.ufl.edu/publication/UW392">critical early phase</a> before they become established. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CMQYFVWH8X5/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Maintaining public support</h2>
<p>Some of these efforts have shown encouraging results. Since 2008, Colorado has operated a <a href="https://coloradosun.com/2022/05/30/aquatic-nuisance-species/">rigorous boat inspection program</a> that has kept zebra and quagga mussels out of state waters. </p>
<p>But prevention isn’t always popular. Officials closed the San Justo Reservoir in central California to the public in 2008 after zebra mussels were found there; residents argue that the closure has <a href="https://panetta.house.gov/media/press-releases/rep-panetta-leadcs-letter-rep-lofgren-request-expedited-process-san-justo">harmed the community</a> and are lobbying the federal government to eradicate the mussels in order to <a href="https://sanbenitolive.com/fishing-advocate-makes-case-to-reopen-san-justo-reservoir/">reopen it for fishing</a>. </p>
<p>Mitigating the destructive effects of invasive species is a complex mission that may not have an obvious endpoint. It requires scientific, technological and historical knowledge, political will and skill to persuade the public that everyone is part of the solution.</p><img src="https://counter.theconversation.com/content/185286/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christine Keiner 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>Zebra and quagga mussels entered the Great Lakes in large ships’ ballast water. Now, local boaters and anglers are spreading them into the southern and western US.Christine Keiner, Chair, Department of Science, Technology, and Society, Rochester Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1844412022-06-24T18:02:25Z2022-06-24T18:02:25ZAfrican lakes emit far less greenhouse gases than feared, European research reveals<figure><img src="https://images.theconversation.com/files/470322/original/file-20220622-13-scwsh7.JPG?ixlib=rb-1.1.0&rect=0%2C5%2C3776%2C949&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Katwe Bay in Lake Edward (Uganda)</span> <span class="attribution"><span class="source">Author</span></span></figcaption></figure><p>One of the keys to predicting climate change is the modelling of how greenhouse gas (GHG) emissions from natural ecosystems might evolve. This first requires estimating as accurately as possible the current GHG emissions from these ecosystems, as well as their causes.</p>
<p>The assessment involves a constant process of re-evaluation, with scientists having to adapt to the latest measurement techniques, theoretical frameworks and expanding databases. As computers’ power increases, mathematical models grow more complex, capturing space and time representations in finer detail. This re-evaluation may be all the more important and frequent for the systems that have been the least studied up to now. </p>
<h2>Lake emissions: a missing piece from the carbon puzzle</h2>
<p>Rivers and lakes, which have the potential to release high quantities of carbon (CO2) and methane (CH4) to the atmosphere, undoubtedly form part of that latter category. While the capacity of ocean and terrestrial systems such as forests to sequester human-induced CO2 was recognised in the late 1950s, it would take another 30 years (almost a generation of scientists!) for the role of rivers, natural lakes and dams in the carbon cycle to be acknowledged in the mid-1990s. Methane emissions from continental waters, in particular, were only estimated in the mid-2000s. This is because rivers and lakes cover a modest area - typically less than 1% of the land surface - and were therefore not regarded as important CO2 or CH4 emitters in the past.</p>
<p>Similarly, scientists until now only had measured emissions from North American and Scandinavian boreal lakes. To make up for the missing parts of the carbon puzzle, such values were extrapolated to lakes in the rest of the world – including tropical lakes. But this is about as inelegant a solution as conflating the ecology of Northern Canadian forests to the Amazonian ones. </p>
<h2>Carbon-sucking phytoplankton … and methane-producing microorganisms</h2>
<p>Our new study on 24 African lakes, which is published today in <em><a href="https://doi.org/10.1126/sciadv.abi8716">Science advances</a></em> , is about to fill this gap. A collaboration between the University of Liège and scientists from KULeuven, the NAFIRRI and the TAFIRI, it reveals GHG emissions from African lakes behaved very differently from the boreal lakes sampled thus far.</p>
<p>For starters, the warm and luminous conditions associated with the tropical “endless summer” meant some African lakes were home to vast quantities of phytoplankton. These micro-algae remove CO2 from the water thanks to the process of photosynthesis. </p>
<p>Such observations invalidate our assumption based on boreal lakes that African counterparts emitted CO2. Due to cooler and darker conditions, lakes in North America and Scandinavia grow very little phytoplankton and limit themselves instead to “composting” the vegetation debris from the surrounding forests. </p>
<p>Their African counterparts, in contrast, are CO2 sinks.</p>
<p>But the warm tropical conditions have a downside. Indeed, heat is favorable to <em>archaea</em>, a category of microorganisms resembling bacteria that produces methane.
The latter also happen to particularly enjoy feeding off the phytoplankton that sink to the bottom of tropical lakes. As a result, methane concentrations were shown to be much higher in African than boreal lakes, and what is “gained” in tropical lakes by sequestering CO2 is “lost” by emitting CH4.</p>
<h2>Why do certain African lakes emit more than others?</h2>
<p>CO2 and CH4 content also varied widely between the 24 lakes based on water depth and colour. </p>
<p>The shallowest of the sampled African lakes was home to the highest biomass of phytoplankton, therefore hosting the lowest CO2 and the highest CH4 concentrations. In shallow lakes, surface waters, which receive the sunlight necessary for photosynthesis, are at the same time in direct contact with the bottom sediments. The bottom sediment provide nitrogen and phosphorus nutrients are also needed for plant growth - like fertilizer in the garden, leading to optimal growth conditions.</p>
<p>Some types of phytoplankton, such as the heat-loving cyanobacteria, also boast physiological features that allow them to reach much higher densities than other micro-algae. Furthermore, proximity to sediments also explains the high CH4 concentrations in shallow lakes.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/470839/original/file-20220624-22-6y78w9.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">Local fishermen help scientists measure CO2 emissions on Lake George in Uganda.</span>
<span class="attribution"><span class="source">Author</span></span>
</figcaption>
</figure>
<p>Our second factor to determine phytoplankton and biomass growth, water colour, depends on the vegetation cover surrounding the lakes. To help yourself visualise this, recall how the puddles you see on a walk in the forest have a tea-looking, brown colour. This is due to the presence of dissolved substances called humic which absorb light and prevent the development of phytoplankton. </p>
<p>Tropical forests bordering African lakes, with their rich soils, are full of the stuff. Conversely, lakes surrounded by savannah in more arid regions of Africa had less humic substances. Their clearer waters allowed the growth of phytoplankton, and thus in this case sequestrated more CO2. </p>
<h2>25 times less CO2 emissions than previously assumed</h2>
<p>Finally, the study drew from a recent spatial database detailing the surface and depth measurements of 72,500 tropical lakes worldwide. An understanding of the mechanisms underlying the production of CO2 and CH4 by lakes (depth and surrounding vegetation cover) allowed for an “informed” rather than a “blind” statistical extrapolation of the data based on a simple average of all the data.</p>
<p>Prior studies assumed tropical lakes emitted up to 1600 mega tons of CO2 per year, equivalent to 40% of global CO2 emissions linked to deforestation or the cumulated emissions of <a href="http://www.globalcarbonatlas.org/en/CO2-emissions">CO2 from Germany, UK, France and Italy</a>. Our research suggests that tropical lakes in fact emit CO2 at a rate 25 times lower.</p>
<p>In conclusion, our research brings good news: until now it was assumed lakes emitted high volumes of CO2 - notwithstanding the modest surfaces they covered. Such beliefs were based on data from lakes in North America and Scandinavia, however, regions where the climate and vegetation cover are conducive to high lake CO2 emissions. In contrast, GHG emissions from tropical lakes are low and had been largely overestimated until now.</p>
<p>The bad news is that because methane producing archaea love warm conditions, future warming of tropical lakes might lead to an increase of CH4 emissions to the atmosphere. Something to keep under surveillance. </p>
<p><em>This study synthesizes measurements obtained over more than 10 years in 24 African lakes including the largest of the African Rift (Victoria, Tanganyika, Albert, Kivu, Edward), during 17 field expeditions, in the framework of 2 BELSPO projects (EAGLES, HIPE) and 5 FNRS projects (TRANS-CONGO, LAVIGAS, TANGAGAS, KYBALGAS, MAITURIK).</em></p><img src="https://counter.theconversation.com/content/184441/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alberto Borges a reçu des financements de BELSPO et du FNRS. </span></em></p>Thanks to their high concentrations of phytoplankton, African lakes emit less CO2 than their boreal counterparts, with important consequences for climate modelling.Alberto Borges, Research Director FRS-FNRS, Associate Professor at ULiège, Université de LiègeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1809892022-04-21T10:23:38Z2022-04-21T10:23:38ZWarmer summers threaten Antarctica’s giant ice shelves because of the lakes they create<figure><img src="https://images.theconversation.com/files/458844/original/file-20220420-16-5zrq74.jpg?ixlib=rb-1.1.0&rect=7%2C14%2C4737%2C3144&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Layered ice sheets can be vulnerable to fracturing.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/elisfanclub/4542347479">Eli Duke/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>During the Antarctic summer, air temperatures get warm enough to melt snow and ice on the surface of the great ice sheets that make up <a href="https://discoveringantarctica.org.uk/oceans-atmosphere-landscape/ice-land-and-sea/ice-sheets-and-glaciation/">around 99%</a> of Antarctica. This melted water collects to form thousands of lakes around the edges of this vast continent. Most of these lakes form on gigantic platforms of floating ice called <a href="https://nsidc.org/cryosphere/quickfacts/iceshelves.html">ice shelves</a>, which extend out from the continent into the sea. </p>
<p>Lakes forming on the surface of these ice shelves can sometimes cause them to <a href="http://www.antarcticglaciers.org/glaciers-and-climate/changing-antarctica/shrinking-ice-shelves/antarctic-supraglacial-lakes-and-ice-shelf-collapse/">break up</a>. The most famous example is the collapse of <a href="https://theconversation.com/antarcticas-ice-shelves-are-trembling-as-global-temperatures-rise-what-happens-next-is-up-to-us-158540">Larsen B</a> ice shelf on the Antarctic Peninsula, which shattered entirely over a matter of weeks in <a href="https://nsidc.org/cryosphere/icelights/2021/09/what-happened-larsen-ice-shelf">2002</a>. </p>
<p>Satellites recorded the appearance and drainage of <a href="https://earthobservatory.nasa.gov/world-of-change/LarsenB">thousands of lakes</a> on Larsen B’s surface before it broke up. Scientists believe meltwater from these lakes widened and deepened cracks and crevasses within the shelf in a process called hydrofracturing.</p>
<p>Ice shelves act as doorstops, supporting vast masses of ice known as glaciers that lie further inland. But if hydrofracturing forces them to break up, these rivers of ice that feed into the ice shelf flow faster into the ocean, contributing to <a href="https://nsidc.org/cryosphere/icelights/2021/09/what-happened-larsen-ice-shelf">rising sea levels</a>. </p>
<figure class="align-center ">
<img alt="A gif showing how lakes contributed to the collapse of the Larsen B ice shelf" src="https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458843/original/file-20220420-13-nvcyej.gif?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">Blue meltwater lakes covered the surface of Larsen B before its collapse.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/system/downloadable_items/1161_3iceshelf-alt.gif">NASA Goddard Space Flight Center</a></span>
</figcaption>
</figure>
<p>Scientists have recently found that lakes are <a href="https://theconversation.com/antarctica-now-has-more-than-65-000-meltwater-lakes-as-summer-ice-melts-124362">more extensive</a> around the Antarctic ice sheet than previously thought. Endurance swimmer <a href="https://lewispugh.com/">Lewis Pugh</a> even swam one kilometre through one of these lakes in 2020 to raise awareness of climate change. But how much does the meltwater stored in these lakes vary between years, and how is this linked to climate conditions? This is something my colleagues and I have explored in a new study, published in <a href="https://www.nature.com/articles/s41467-022-29385-3">Nature Communications</a>.</p>
<p>Our research uncovers for the first time how meltwater lake coverage and volumes vary between years around the whole Antarctic ice sheet. We analysed over 2,000 satellite images of the East Antarctic sheet – the world’s largest – to record the changing size and volume of these lakes over the past seven years. </p>
<p>Until now, observations of surface meltwater lakes on the East Antarctic ice sheet were relatively scarce and their year-to-year changes were largely unknown, making it difficult to assess whether some ice shelves were close to breaking up under the effects of climate change. </p>
<figure class="align-center ">
<img alt="A diagram showing major lakes in East Antarctica" src="https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=577&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=577&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=577&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=725&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=725&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458849/original/file-20220420-34130-dw5jnm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=725&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Surface meltwater lakes are visible in satellite images on ice shelves around East Antarctica.</span>
<span class="attribution"><span class="source">Jennifer Arthur</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We found that total lake volume varies between years by as much as 200% on some ice shelves and by up to 72% across the entire ice sheet, with large differences between ice shelves. Across the whole ice sheet, total meltwater stored in lakes peaked in 2017. That water could have filled about 930,000 Olympic swimming pools. </p>
<h2>More warming means more lakes</h2>
<p>Melting at the surface of the sheet doesn’t just form lakes: the water also seeps into air spaces in the layers beneath the surface, where it freezes as temperatures get colder. These layers, called firn, are made up of old snow that has not yet been compressed into ice. </p>
<p>If more melting occurs than snowfall each year, air in the firn becomes replaced with refrozen meltwater. When that happens, meltwater forming the next summer is forced to collect on the surface as lakes. The more surface melting there is, the more the firn gets saturated like a sponge and so the more lakes form on the surface, increasing the risk of fracturing. </p>
<p>To investigate lake variability between years, we ran model simulations of firn air content, surface melt and runoff on Antarctic ice shelves where lakes form. We found that across the whole ice sheet, summer air temperatures and the amount of air in the firn are important factors affecting the total area and volume of meltwater lakes. We’ve noticed on satellite images that on some ice shelves lake coverage is already expanding into regions vulnerable to fracturing.</p>
<figure class="align-center ">
<img alt="A bright blue lake on an ice shelf" src="https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/458841/original/file-20220420-19-dk3y5k.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">A meltwater lake formed on Sørsdal glacier in East Antarctica.</span>
<span class="attribution"><span class="source">Sue Cook, UTAS</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Interestingly, we found large differences between where we’ve observed lakes in satellite images and the amount of meltwater that can form lakes predicted by our models. This means local climate conditions are more important than we thought in predicting surface melting and therefore lake formation. Our climate models still need refining to allow these processes to be fully captured to better predict future surface meltwater around Antarctica.</p>
<p>In a <a href="https://www.carbonbrief.org/guest-post-the-fate-of-antarctic-ice-shelves-at-1-5c-2c-and-4c-of-warming">warming world</a>, these lakes are likely to continue to spread onto ice shelves that are vulnerable to breaking up. Our work is a step forward in understanding not just where lakes are forming now across the whole ice sheet, but what controls the way they change every year. This is key to predicting which ice shelves are most at risk of collapse, as well as for improving model projections of Antarctica’s contribution to sea-level rise.</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>Jennifer Arthur receives funding from a Natural Environment Research Council doctoral studentship grant.</span></em></p>Melting lakes on ice shelves can widen cracks within them - new research shows how these lakes change across the world’s largest sheet.Jennifer Arthur, PhD student in Cryospheric Remote Sensing, Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1749002022-01-16T07:20:07Z2022-01-16T07:20:07ZLakes in the Democratic Republic of Congo are contested spaces. Here’s why<figure><img src="https://images.theconversation.com/files/440734/original/file-20220113-8662-12c7wxu.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">Getty Images</span></span></figcaption></figure><p>The lakes of the Democratic Republic of Congo (DRC) play a big part in people’s lives – socially, politically and economically. But lake fishing communities find themselves at the intersection of geography, war and authority, as rebel groups and conservation managers also claim spaces and resources.</p>
<p>By some estimates there are over 70 armed groups in the country, led by warlords, traditional tribal elders, village heads and politically motivated resistance fighters. </p>
<p>Lake Edward is also a conservation area and park managers try to limit the illegal fishing there. This creates conflict too. People who live around the lake and depend on it for livelihoods have to deal with both rebel groups and park management. </p>
<p>In today’s episode of Pasha, Esther Marijnen, assistant professor in sociology of development and change at Wageningen University, takes us through her <a href="https://www.sciencedirect.com/science/article/pii/S0016718521002712">research</a> on the topic. It’s important to get a historical perspective, she says, to understand why the conflict persists. </p>
<hr>
<p><strong>Photo</strong>
“The fishing village of Kavanyongi on the northern shores of Lake Edward” by Brent Stirton/Getty Images for WWF-Canon. Found on <a href="https://www.gettyimages.com/detail/news-photo/the-fishing-village-of-kavanyongi-on-the-northern-shores-of-news-photo/455175811?adppopup=true">Getty Images</a>.</p>
<p><strong>Music</strong>
“Happy African Village” by John Bartmann, found on <a href="http://freemusicarchive.org/music/John_Bartmann/Public_Domain_Soundtrack_Music_Album_One/happy-african-village">FreeMusicArchive.org</a> licensed under <a href="https://creativecommons.org/publicdomain/zero/1.0/">CC0 1</a>.</p>
<p>“African Moon” by John Bartmann, found on <a href="http://freemusicarchive.org/music/John_Bartmann/Public_Domain_Soundtrack_Music_Album_One/happy-african-village">FreeMusicArchive.org</a> licensed under <a href="https://creativecommons.org/publicdomain/zero/1.0/">CC0 1</a>.</p><img src="https://counter.theconversation.com/content/174900/count.gif" alt="The Conversation" width="1" height="1" />
Some lakes in the DRC should be thought of as rebellious landscapes having their own social, political and cultural dynamics.Ozayr Patel, Digital EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1734712021-12-20T16:48:54Z2021-12-20T16:48:54ZOur lakes are losing their ice cover faster than ever — here’s what that means for us<figure><img src="https://images.theconversation.com/files/438131/original/file-20211216-23-1c590ch.jpg?ixlib=rb-1.1.0&rect=0%2C14%2C2484%2C1632&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The decreasing ice cover in northern lakes will severely impact the lake ecology as well as winter recreation activities in the northern region.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 175px; border: none; position: relative; z-index: 1;" allowtransparency="" src="https://narrations.ad-auris.com/widget/the-conversation-canada/our-lakes-are-losing-their-ice-cover-faster-than-ever--—-here-s-what-that-means-for-us" width="100%" height="400"></iframe>
<p>Every winter when Lake Suwa in Japan freezes, locals believe that the Shinto male god Takeminakata crosses the frozen lake with his dragon to visit the female god Yasakatome. He leaves only his footsteps on the ice in the form of a <a href="https://www.nationalgeographic.com/science/article/ice-lake-suwa-japan-torne-river-climate-change-monk-shinto">sinusoidal ice ridge called the <em>omiwatari</em></a>.</p>
<p>In 1397, Shinto priests began celebrating and recording the appearance of the <em>omiwatari</em>. <a href="https://www.japantimes.co.jp/news/2019/12/16/national/nagano-lake-suwa-climate-change/">They used the direction of the cracks left by the <em>omiwatari</em></a> to forecast the agricultural harvest for the upcoming summer. In the first 250 years of the ice record, <a href="https://doi.org/10.1038/srep25061">Lake Suwa froze every year, except for three years</a> during which time the region saw widespread famine. Since the turn of the millennium, however, the lake has only frozen seven times.</p>
<p>Lake Suwa is one of many lakes in the Northern Hemisphere that is rapidly losing its ice cover. In our research, we found that <a href="https://doi.org/10.1029/2021JG006348">ice is forming later and melting earlier across these lakes, leaving a shorter period of seasonal ice cover</a>. In recent decades, many lakes are experiencing the shortest seasons of ice cover ever recorded. </p>
<p>If the ice cover in northern lakes continues to decline at the same pace, it will have severe ecological and cultural consequences.</p>
<figure class="align-center ">
<img alt="Melting ice chunks floating on Lake Sunapee, New Hampshire" src="https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437596/original/file-20211214-13-8ci4fo.jpeg?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">Lakes in the Northern Hemisphere are losing their ice cover faster than ever.</span>
<span class="attribution"><span class="source">(Midge Eliassen)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Lakes losing ice at rapid rates</h2>
<p>Ice duration was more than two weeks shorter per century, on average, since the Industrial Revolution, with lakes losing up to 34 per cent of their total ice cover. In the past 25 years, the <a href="https://www.washingtonpost.com/weather/2021/11/04/great-lakes-fastest-warming-study/">loss of ice escalated with lakes losing ice six times faster</a> than any other period in the past 100 years. </p>
<p>Around 15,000 lakes, including Lake Suwa and the North American Great Lakes — Lake Michigan and Lake Superior — are beginning to <a href="https://www.bbc.com/news/science-environment-47029482">remain ice-free in some winters</a>. Lakes situated at lower latitudes and in some coastal regions, where winter air temperatures hover around 0 C (the freshwater freezing point) in addition to large, deep lakes in colder regions, are most sensitive to experiencing ice-free winters. </p>
<p><a href="https://doi.org/10.1038/s41558-018-0393-5">Large, deep lakes</a>, such as the North American Great Lakes, require sustained cold temperatures to sufficiently cool their waters to allow ice to form, as deeper lakes take longer to cool in autumn due to their immense thermal mass. </p>
<p>Larger lakes with a longer fetch — the area over which the wind blows — also tend to freeze later because they are more sensitive to increased wind action breaking up the initial skim of ice on the lake surface.</p>
<h2>Why does ice loss matter?</h2>
<p>Lake Superior is one of the <a href="https://www.theweathernetwork.com/en/news/climate/impacts/lake-superior-is-one-of-the-fastest-warming-lakes-on-the-planet">fastest warming lakes</a> in the world. Since 1867, it has lost over two months of ice cover. By removing the “lid” of ice, evaporation rates can increase in Lake Superior, as well many other <a href="https://doi.org/10.1038/s41561-018-0114-8">lakes across the Northern Hemisphere</a>, further affecting water availability. As lakes transition to becoming ice-free and the physical barrier between the lake surface and the atmosphere is removed, the <a href="https://theconversation.com/extreme-heat-waves-are-putting-lakes-and-rivers-in-hot-water-this-summer-164227">potential for evaporation</a> to occur year-round increases. </p>
<p>Ice loss can also lead to year-round impacts on lake ecology. For example, an earlier ice break-up in the spring leads to a <a href="https://www.carbonbrief.org/climate-change-could-cause-irreversible-impacts-to-lake-ecosystems?">longer open-water season</a> and <a href="https://theconversation.com/extreme-heat-waves-are-putting-lakes-and-rivers-in-hot-water-this-summer-164227">warmer summer water temperatures</a>. </p>
<figure class="align-center ">
<img alt="A lake covered with a layer of green algae ." src="https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438282/original/file-20211217-19-onqnhr.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">Reduced ice cover on northern lakes can contribute to summer blue-green algal blooms which cause the depletion of dissolved oxygen within the lake waters.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Less ice cover, warmer temperatures, and increased storm events deliver more nutrients to the lakes, leading to widespread summer <a href="https://www.greatlakesnow.org/2021/08/lake-superior-summer-algae-bloom/">blue-green algal blooms</a>, also known as cyanobacterial blooms, which were once thought to be implausible in the cold, deep and pristine waters of Lake Superior.</p>
<p>In some lakes, algal blooms are becoming particularly thick, decreasing the amount of sunlight that reaches deeper waters. With less sunlight, photosynthesis is reduced, ultimately leading to a decrease in the concentration of <a href="https://doi.org/10.1038/s41586-021-03550-y">dissolved oxygen</a> available to support aquatic life.</p>
<p>Some fish communities rely on long winters. For example, following short winters, <a href="https://doi.org/10.1038/ncomms8724">Lake Erie yellow perch</a> produced smaller eggs and weaker young fish that were less likely to survive to adulthood. Fish life stages most sensitive to temperature changes in the earlier part of the open-water season include <a href="https://doi.org/10.1007/s10584-020-02887-z">embryos and spawning adults</a>. Furthermore, an earlier start to summer (i.e., due to earlier ice loss) can cause mismatches in the timing of critical activities, such as spawning and foraging, often with widespread ramifications across the food web. </p>
<figure class="align-center ">
<img alt="A frozen lake in Finland" src="https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437597/original/file-20211214-21-sjsdch.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">Reducing greenhouse gases and slowing down climate change is the only way to save lake ice cover, and protect the local ecology and culture that depends on it.</span>
<span class="attribution"><span class="source">(Johanna Korhonen)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A future without lake ice</h2>
<p>As temperatures continue to warm globally due to anthropogenic climate change, <a href="https://doi.org/10.1038/s41558-018-0393-5">215,000 lakes may no longer freeze every winter</a> and almost 5,700 lakes may permanently lose ice cover by the end of the century. <a href="https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2020GL091108">Large and deep lakes, including Lakes Michigan and Superior, are most likely to permanently lose ice cover</a> as early as the 2060s if global air temperatures continue to rise. </p>
<p><a href="https://www.esa.int/Applications/Observing_the_Earth/Space_for_our_climate/Humans_to_blame_for_warming_lakes">Our research</a> has shown that the global decline of lake ice cover in recent decades can <a href="https://doi.org/10.1038/s41561-021-00833-x">only be explained</a> by increased greenhouse gas emissions since the Industrial Revolution. There is <a href="https://www.bbc.com/future/article/20211115-how-cities-are-going-carbon-neutral">no magic solution</a> beyond limiting greenhouse gas emissions to slow climate change and ultimately preserve lake ice cover. </p>
<p>For northern communities, ice cover provides a way of life in the winter. Countless Canadian kids have learned how to skate and play hockey at nearby lakes, local ponds, and backyard ice rinks, just as <a href="https://www.si.com/nhl/2019/04/22/climate-change-canada-winter-sports-hockey-backyard-rinks">hockey legend, Wayne Gretzky, did in Brantford, Ont</a>. Warmer winters are contributing to shorter outdoor <a href="https://www.nytimes.com/2018/03/20/climate/canada-outdoor-rinks.html">ice hockey</a> and <a href="https://www.nature.com/articles/nclimate2465">skating seasons</a>. </p>
<p>Ice fishing tournaments are increasingly cancelled, with widespread consequences for local economies. For example, the winter ice fishing season in Lake Winnipeg alone generates over <a href="https://mwf.mb.ca/archives/674">$200 million</a> each year. </p>
<p>The increasingly unpredictable and unstable ice cover is a safety hazard and is contributing to <a href="https://theconversation.com/winter-drownings-may-increase-in-northern-countries-as-ice-thins-with-climate-change-150029">increased fatal winter drownings</a> through ice in northern countries, with <a href="https://www.nytimes.com/2020/11/20/climate/thin-ice-winter-drowning.html">northern Indigenous communities at most risk</a>. </p>
<figure class="align-center ">
<img alt="The view of the ice cover and ice ridges on Lake Suwa, Japan, with the mountains in the background." src="https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437594/original/file-20211214-19-xx6j1w.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">The ice ridges on Lake Suwa form an integral part of the community’s spiritual traditions and culture.</span>
<span class="attribution"><span class="source">(Satoe Kasahara)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Finally, for the Shintos living in Suwa, protecting ice cover is essential to preserving the spiritual traditions maintained by generations of Shinto priests. At current rates of greenhouse gas emissions, climate projections predict that the lake will <a href="https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2020GL091108">rarely freeze in the very near future, and following 2040 will never freeze again</a>. </p>
<p>However, slowing climate change and limiting temperature increases below 1.5 C will allow Takeminakata to periodically cross the frozen lake to visit Yasakatome as he has done for centuries.</p><img src="https://counter.theconversation.com/content/173471/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sapna Sharma receives funding from NSERC, Ontario Ministry of Economic Development and Innovation, Ontario Ministry of Environment, Conservation and Parks, Genome Canada, and the York University Research Chair Program. She is affiliated with the Royal Canadian Institute for Science. </span></em></p><p class="fine-print"><em><span>David Richardson has received funding from National Science Foundation and New York State Water Resources Institute. </span></em></p><p class="fine-print"><em><span>Iestyn Woolway receives funding from the Natural Environment Research Council. </span></em></p>Lakes in the northern hemisphere are rapidly losing their ice cover due to rising greenhouse gas emissions. The only way to preserve lake ice is to limit GHG emissions and slow down climate change.Sapna Sharma, Associate Professor and York University Research Chair in Global Change Biology, York University, CanadaDavid Richardson, Professor, Department of Biology, State University of New York at New PaltzIestyn Woolway, Research Fellow in Climate Science, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1694362021-12-08T20:49:45Z2021-12-08T20:49:45ZHow more motorboat collisions are leaving turtles shell-shocked and mutilated<figure><img src="https://images.theconversation.com/files/435725/original/file-20211205-13-ew6ffn.JPG?ixlib=rb-1.1.0&rect=0%2C9%2C3264%2C2433&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Northern map turtles are only one of the freshwater turtle species threatened by human activity.</span> <span class="attribution"><span class="source">(Grégory Bulté)</span>, <span class="license">Author provided</span></span></figcaption></figure><iframe style="width: 100%; height: 175px; border: none; position: relative; z-index: 1;" allowtransparency="" src="https://narrations.ad-auris.com/widget/the-conversation-canada/how-more-motorboat-collisions-are-leaving-turtles-shell-shocked-and-mutilated" width="100%" height="400"></iframe>
<p>As a wildlife ecologist, I have been keeping tabs on the northern map turtles of Lake Opinicon since 2003. One of these turtles is CJV. She is one of more than 1,800 turtles encountered during our monitoring program. </p>
<p>Every spring, we catch as many turtles as we can. Each turtle is measured, examined for signs of diseases or injuries, and marked with a unique combination of small notches on the edge of its shell. This is how I recognized CJV on May 31, 2019.</p>
<p>CJV and I go way back, to May 19, 2005, to be exact, but we haven’t seen each other since. The passage of time has left its marks on both of us. For starters, I am noticeably greyer, balder and less fit. As for CJV, she has grown a few millimetres, but that would be nearly impossible to tell without very accurate calipers. </p>
<p>But the biggest change in CJV’s appearance is her shell. After missing in action for 14 years, CJV showed up with a large but partially healed scar running from the left side of her shell to her spine. When and where she got injured is anyone’s guess, but the cause of the injury is clear. No natural predators can slice through her bony armour — but a sharp boat propeller surely can. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an overhead shot of a northern map turtle missing a fragment of its shell" src="https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=520&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=520&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435680/original/file-20211204-15-7eudw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=520&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">CJV is a female northern map turtle from Lake Opinicon, Ont., with a large boat propeller scar.</span>
<span class="attribution"><span class="source">(Grégory Bulté)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Concerning rates</h2>
<p>Lake Opinicon is nested in the <a href="https://whc.unesco.org/en/list/1221/">Rideau Canal World Heritage Site</a>, and at the heart of the <a href="https://www.frontenacarchbiosphere.ca/">Frontenac Arch Biosphere Reserve</a>. Unfortunately, these designations are doing little to prevent turtles from being chopped up. </p>
<p>When I first captured CJV in 2005, seven per cent of all the females we examined were scarred. When we met again in 2019, the number had climbed to 13 per cent. But mutilated turtles are not unique to Lake Opinicon. </p>
<p>In 2010, we reported that <a href="https://doi.org/10.1002/aqc.1063">13 per cent of female map turtles in the St. Lawrence Island National Park had propeller injuries</a>. Around the same time, <a href="https://laurentian.ca/faculty/jlitzgus">researchers</a> from Laurentian University reported that more than <a href="https://doi.org/10.1670/12-161">28 per cent of northern map turtles in the Trent Severn Waterway had been struck by a propeller</a>. </p>
<p>There are <a href="https://www.natureconservancy.ca/en/what-we-do/resource-centre/featured-species/turtles-of-canada.html">eight species of freshwater turtles</a> in Canada. All are federally listed as <a href="https://www.cosewic.ca/index.php/en-ca/">Species at Risk</a>, meaning that to remain a part of our lakes, ponds and rivers, they need protection and conservation efforts. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="two different photos of a turtle showing shell and face damage from a propeller" src="https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435681/original/file-20211204-19-vh548k.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">A close call: a male northern map turtle from Lake Opinicon showing a severe propeller injury to its shell and face.</span>
<span class="attribution"><span class="source">(Grégory Bulté)</span></span>
</figcaption>
</figure>
<h2>Betting on the long haul</h2>
<p>It is not a coincidence that all our native turtles are in trouble — <a href="https://doi.org/10.1016/j.cub.2020.04.088">the global group of about 350 species is in a dire situation</a>. Sixty-one percent of turtle species are extinct or threatened by extinction. This grim statistic does not have a single root cause. Like most precarious wildlife, turtles are threatened by the usual suspects of habitat loss, poaching, direct mortality from human activities and pollution. </p>
<p>Unfortunately, turtles have something else going against them: a 200-million-year-old gambling habit. When it comes to procreation, turtles play a numbers game: they lay as many eggs as they can over their lifespan, hoping some will eventually make it. </p>
<p>Turtles do not care for their eggs or young in the same way birds and mammals do, and without any care or protection, most eggs and babies are eaten by predators or otherwise die from cold, droughts, floods or other weather hazards. If a female lays enough eggs, however, some will hatch and grow into adults. Longevity is key here, and turtles evolved <a href="https://www.livescience.com/why-turtles-live-so-long.html">remarkably long life spans</a>.</p>
<p>Turtles have successfully gambled their way through the last <a href="http://www.prehistoric-wildlife.com/species/p/proganochelys.html">200 million years</a>, but the playing field has changed. Human activities are cutting the long lives of these animals too short for many females to have won their reproductive bet against time. So here we are with dwindling turtle populations in our protected areas.</p>
<p>We can’t say for sure if, or how much, collision with boats threatens the persistence of turtles because an important piece of information is still missing: the proportion of turtles dying from their propeller injuries. Finding dead turtles in nature is not easy because biologists have fierce competition from scavengers when it comes to finding animal carcasses. </p>
<p>However, what we do know raises a red flag. Many turtle populations are already experiencing an inflated amount of adult mortality. Roads alone kill countless adult turtles every year so boat mortality need not be high to precipitate the decline of some turtle populations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A hand holding four young northern map turtles" src="https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435697/original/file-20211204-17-1b4j81k.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">Four three-year-old northern map turtles — the females have eight years to go before maturing.</span>
<span class="attribution"><span class="source">(Grégory Bulté)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Testimonial scars</h2>
<p>The visible scars of turtles are a testimony to the pressure recreational boating exerts on aquatic wildlife. Motorboats affect aquatic wildlife and their habitats in many ways: noise pollution, chemical pollution, wakes, erosion, collisions. </p>
<p>In a recent meta-analysis of 94 studies on the effects of water-based recreation on freshwater ecosystems, researchers found <a href="https://doi.org/10.1098/rspb.2021.1623">boats to consistently cause negative impacts on wildlife</a>. Some of these impacts can be subtle but nonetheless important: the noise from motors alone can affect the behaviour and physiology of nesting bass. Disturbances from motorboats can also reduce the foraging time of waterfowl. </p>
<p>According to the <a href="https://www.nmma.ca/press/article/23568">National Marine Manufacturer Association Canada</a>, the sales of outboard engines increased by 17 per cent between 2019 and 2020, and is now at a record high. With such enthusiasm for recreational powerboating, the impacts on turtles and other wildlife need to be measured. This data will dictate the need for conservation actions such as outreach programs, best practices and, if necessary, regulations such as limiting engine size, or restricting traffic. </p>
<p>Mutilated turtles like CJV are a reminder that lakes and rivers are <a href="https://doi.org/10.1111/brv.12480">living and fragile ecosystems</a>. These ecosystems and the species they host — <a href="https://doi.org/10.1093/biosci/biy095">including turtles</a> — provide us with countless cultural, economic, health and aesthetic services. These services are increasingly at odds with certain forms of recreational boating. </p>
<p>Without changes in how we perceive and use our lakes and rivers for recreation, we will find more injured turtles … until we won’t find any turtles at all.</p><img src="https://counter.theconversation.com/content/169436/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Some of the research presented in this article was funded by a Species at Risk Grant from Parks Canada and NSERC. </span></em></p>Increased motorboat activity has resulted in an alarming increase in turtle injuries. Northern map turtles are an at-risk species, and boat collisions threaten their survival.Grégory Bulté, Instructor, Ecology and Evolutionary Biology, Carleton UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1716572021-11-16T20:34:44Z2021-11-16T20:34:44ZVery hungry caterpillars can have large effects on lake quality and carbon emissions<figure><img src="https://images.theconversation.com/files/432041/original/file-20211115-17-zxtklw.JPG?ixlib=rb-1.1.0&rect=47%2C35%2C3898%2C2173&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">These insects are basically little machines that convert carbon-rich leaves into nitrogen-rich poo.</span> <span class="attribution"><span class="source">(John Gunn)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Outbreaks of invasive moth caterpillars, <em>Lymantria dispar dispar</em>, and forest tent caterpillar moths, <em>Malacasoma disstria</em>, occur at least every five years in temperate forests. The insects munch through so many leaves that <a href="https://doi.org/10.1038/s41467-021-26666-1">our research has found</a> the resulting decrease in leaf-fall and increase in caterpillar poop hugely alter the way nutrients, particularly carbon and nitrogen, cycle between land and nearby lakes.</p>
<p>Nitrogen-rich insect excrement, called frass, can wash into lake water and act as fertilizer for microbes. These microbes can then release carbon dioxide into the atmosphere as they metabolize the frass. In years with insect outbreaks, the large quantities of frass may favour the growth of bacteria that release greenhouse gases in lakes <a href="https://doi.org/10.4319/lo.1984.29.2.0298">overpowering the lake algae that remove carbon dioxide from the atmosphere</a>.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/why-an-invasive-caterpillar-is-munching-its-way-through-tree-leaves-in-the-largest-outbreak-in-decades-163346">Why an invasive caterpillar is munching its way through tree leaves, in the largest outbreak in decades</a>
</strong>
</em>
</p>
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<figure class="align-right ">
<img alt="Caterpillars on a chewed green leaf." src="https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=412&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=412&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=412&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=518&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=518&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432074/original/file-20211115-13-1j2he1b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=518&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tree leaves eaten by caterpillars on Montreal’s Mount Royal in July 2021.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Paul Chiasson</span></span>
</figcaption>
</figure>
<p>These insects are basically little machines that convert carbon-rich leaves into nitrogen-rich poo. The poo drops into lakes instead of the leaves, and this significantly changes the water chemistry. We think it will further increase the extent to which lakes are sources of greenhouse gases. </p>
<p>As the climate in the world’s temperate region shifts, insect populations are expected to increase and move northwards. This puts <a href="https://doi.org/10.1046/j.1365-2486.2002.00451.x">northern forests at increased risk of defoliator outbreaks in the future</a>, potentially causing greater quantities of carbon dioxide to be released from nearby lakes. Climate change is also expected to favour the growth of broad-leaved deciduous trees around the lakes, which we have found will amplify the insects’s impact.</p>
<h2>Where is the good news?</h2>
<p>While the impacts of insect defoliation appear to be on the rise in both frequency and severity, lake waters across the Canadian Shield are also undergoing a <a href="https://doi.org/10.1038/444283a">process called browning</a> due to a build up of tea-like dissolved organic carbon in lake water. </p>
<p>This declining clarity of lakes has been attributed to many factors including climate change and their recovery from historical acid rain and logging activities. Our 32-year-long monitoring study showed that an outbreak of leaf-munching caterpillars can effectively offset an entire year’s worth of carbon accumulation in nearby lakes, significantly improving water clarity.</p>
<figure class="align-center ">
<img alt="A view of autumn trees along a lake shoreline" src="https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432078/original/file-20211115-13-hlgdt0.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">An outbreak of leaf-munching caterpillars can effectively offset an entire year’s worth of carbon accumulation in nearby lakes, significantly improving water clarity.</span>
<span class="attribution"><span class="source">(Unsplash)</span></span>
</figcaption>
</figure>
<p>In years without outbreaks of leaf-eating insects, carbon and nitrogen entering lakes usually comes from decaying leaves and conifer needles. These inputs typically peak in quantity in autumn. In outbreak years, we found that nearby freshwater lakes, especially those surrounded by deciduous forests had one-third less dissolved carbon or “forest tea” in the water, because the hungry caterpillars effectively held back the flow of carbon to the lake.</p>
<p>The lasting benefits of these marauding insects becomes evident when the invasive insects encounter already stressed trees, such as the stunted birch forest surrounding the massive metal smelters in Sudbury, Ont. This 80,000 hectare industrial area is undergoing a remarkable natural recovery of its own, because of a <a href="https://theconversation.com/what-mining-oil-and-gas-industries-can-learn-from-sudbury-the-city-that-went-from-major-polluter-to-thriving-environment-165595">98 per cent reduction in acid and metal particulate emissions</a> from what was <a href="https://www.goodnewsnetwork.org/sudbury-now-has-cleanest-air-in-region/">the world’s largest point sources of sulphur pollution as recently as the 1970s</a>. The legacy of soil loss, contamination and degradation in Sudbury clearly puts trees at a disadvantage in the battle with defoliating insects.</p>
<h2>Caterpillars as tiny plows?</h2>
<p>Trees can’t flee from insects but usually can survive multiple heavy attacks. However, trees in the industrial barrens of Sudbury don’t fare so well, because of all the other stresses they face. </p>
<p>These stressors include the loss of soil moisture and organic matter, and decades of accumulated toxic metal particles from the smelters. The result is that these stressed trees present themselves as a delicious food source for caterpillars and other insects and the landscape is often littered with dead and dying trees on their way to becoming soil.</p>
<p><a href="https://doi.org/10.1093/ee/nvz096">In earlier lab experiments</a>, we showed that when we fed <em>L. dispar</em> caterpillars leaves from the stressed white birch trees of the industrial barrens they ate more leaves and produced far more frass, which increased plant growth in soil that had received this rain of poo. </p>
<p>Yes, the insects are giving the struggling trees a very hard time at the industrial sites. But the improving soil quality is the real winner. </p>
<p>Healthy <a href="https://e360.yale.edu/features/soil_as_carbon_storehouse_new_weapon_in_climate_fight">soil is one of the largest and safest places to sequester carbon from the atmosphere</a>, key in our fight against climate change. As every farmer knows, protecting and restoring soil quality is also essential for sustainable agriculture. That is why well-informed farmers regularly try to stop extracting nutrients from the soil and plow in a nutrient-rich fodder crop like alfalfa to rebuild the soil.</p>
<p>Our research shows that these hungry caterpillars now appear to play surprisingly large roles in altering key features of the global carbon cycle, but we also now think of them as tiny plows that can help improve degraded soils.</p><img src="https://counter.theconversation.com/content/171657/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Gunn receives funding from organisation.
NSERC, CRC, CFI, Mitacs, OCE, Vale, Glencore, Wildlife Conservation Society, DFO, Friends of Killarney</span></em></p><p class="fine-print"><em><span>Andrew J Tanentzap receives funding from the Natural Environment Research Council, Biotechnology and Biological Sciences Research Council, and European Research Council.</span></em></p><p class="fine-print"><em><span>Samuel Woodman receives funding from NSERC and the Cambridge Trust. </span></em></p>As environmental engineers, invasive caterpillars can have remarkable effects on water quality and soil conditions. But from a climate perspective they’re pretty much a nuisance.John Gunn, Canada Research Chair in Stressed Aquatic Systems, Laurentian UniversityAndrew J Tanentzap, Reader in Global Change Ecology, University of CambridgeSamuel Woodman, PhD Student, Ecosystem and Global Change, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1692222021-10-25T15:12:38Z2021-10-25T15:12:38ZTiny swimming creatures can create currents in lake water – new research<figure><img src="https://images.theconversation.com/files/427563/original/file-20211020-13-197ipb5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3834%2C2160&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lake Windermere, in England's Lake District, experiences different mixing processes in its water column.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/75487768@N04/50995512533">BarnyZ/Flickr</a></span></figcaption></figure><p>Lakes are usually pictured as tranquil environments, largely uninfluenced by the enormous <a href="https://theconversation.com/the-untapped-potential-of-our-tides-14943">tidal power</a> which drives the oceans. But the surface winds that act upon lakes can significantly alter the environment in which many lake species thrive – particularly during summer.</p>
<p>Our recent research suggests another factor might play a significant role in mixing up a lake’s water: the movement of the animals that live in it, including microscopic zooplankton. This sheds light on how even the tiniest of organisms can contribute to the physical processes that make lake and ocean environments so extraordinary.</p>
<p>We already knew winds could induce <a href="https://www.researchgate.net/profile/Stefano-Simoncelli-3/publication/319945918/figure/fig2/AS:667869633314837@1536243937870/Sketch-illustrating-main-mixing-processes-operating-in-three-different-lake-regions-In.png">water movement</a> that extends throughout the full depth of a lake, commonly referred to as the “<a href="https://wwz.ifremer.fr/gm_eng/Understanding/Our-research-issues/Hydrothermal-systems/The-water-column#:%7E:text=The%20water%20column%20is%20a,for%20a%20defined%20geographical%20point.">water column</a>”. Mixing between surface and deep waters is essential for maintaining a healthy lake ecosystem. </p>
<p>This mixing drives the exchange of oxygen from the lake surface to the bottom layer, reducing production of the potent <a href="https://theconversation.com/emissions-of-methane-a-greenhouse-gas-far-more-potent-than-carbon-dioxide-are-rising-dangerously-142522">greenhouse gas methane</a> in the sediment on the floor of the lake. Mixing can also allow nutrients, which are essential for species like <a href="https://oceanservice.noaa.gov/facts/phyto.html#:%7E:text=Phytoplankton%20are%20microscopic%20marine%20algae.&text=Phytoplankton%2C%20also%20known%20as%20microalgae,where%20sunlight%20penetrates%20the%20water.">phytoplankton</a> living near the lake’s surface, to be transported upwards.</p>
<p>Yet in the most tranquil waters of a lake – near the bed – scientists have for a while suspected that animal life may contribute to <a href="http://www.epa.state.il.us/water/conservation/lake-notes/lake-stratification-and-mixing/lake-stratification.pdf">lake mixing</a>. By moving their fins, antennae or legs, swimming organisms can generate a variety of movements which combine to form <a href="https://oceanservice.noaa.gov/facts/eddy.html">eddies</a> – dynamic circular currents of water – in a process known as “<a href="http://jeb.biologists.org/content/215/6/1040">biogenic mixing</a>”. Although studies of ocean environments have suggested how this might happen, mainly through lab <a href="https://www.science.org/content/article/can-sea-monkeys-stir-sea">experiments</a> or using numerical simulations, evidence of this process in lakes is limited. </p>
<figure class="align-center ">
<img alt="Lake Furnace, Ireland" src="https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425539/original/file-20211008-25-7s729j.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">Lakes host entire complex ecosystems.</span>
<span class="attribution"><span class="source">Dr Mikkel Andersen</span></span>
</figcaption>
</figure>
<p>Our <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020WR029441">study</a> of Windermere, a large lake in Cumbria’s Lake District National Park, found evidence of significant and persistent biogenic mixing in lakes. This suggests that previous studies may have missed a critical mixing process in <a href="https://www.nature.com/scitable/knowledge/library/ponds-and-lakes-a-journey-through-the-25982495/">lake ecosystems</a>, with implications for our understanding of how they respond to environmental change.</p>
<h2>Biogenic mixing</h2>
<p>To study this phenomenon, we used acoustic <a href="https://www.whoi.edu/what-we-do/explore/instruments/instruments-sensors-samplers/acoustic-doppler-current-profiler-adcp/">Doppler profilers</a>. These instruments send out sound waves which are reflected back by suspended particles, such as zooplankton, in the water column. </p>
<p>The wavelength of the returning sound differs from that of the outgoing signal, which allows us to measure the velocity of the water. Once we know the velocity at different positions in the water column, we can estimate the amount of mixing that takes place.</p>
<p>Our Doppler profilers, which were recording both water current velocities and the movement made by organisms swimming through the water column, indicated that mixing produced by swimming organisms is strongest near the bottom of the lake. </p>
<p>The mixing we observed occurred in a regular 24-hour period, which was quietest close to midnight. This suggested that high concentrations of organisms were moving vertically from deep water up towards the lake surface during the hours of darkness, before returning to deeper water before dawn where they stayed during daylight hours. This is known as “<a href="https://www.cell.com/current-biology/pdf/S0960-9822(14)01067-7.pdf">Diel vertical migration</a>”, and is a characteristic behaviour of zooplankton.</p>
<p>We also detected a smaller mixing process taking place at the <a href="https://oceanservice.noaa.gov/facts/thermocline.html">thermocline</a>. This is a region within lakes and oceans where warmer surface waters and cooler bottom waters are separated during summer. As the sun heats the lake surface, cooler waters (which are denser) sink to the depths of the lake, resulting in a layered water column of varying temperatures.</p>
<p>The thermocline is somewhat of a haven for aquatic organisms, allowing them access to both the warm well-oxygenated water above and the cool nutrient-rich water below, while also providing a potential escape from predators often present in well-lit surface layers. </p>
<figure class="align-center ">
<img alt="Tiny organism under a microscope" src="https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/425540/original/file-20211008-21-mtoxz1.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">Even microscopic organisms like this zooplankton, <em>Daphnia pulex</em>, play their part in mixing lake waters.</span>
<span class="attribution"><span class="source">Dr Ellie Mackay and Dr Stephen Thackeray</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our data indicated that the peak in mixing at the thermocline – around midnight – was the opposite of the peak observed near the lake bed. That’s because this region is where many of the upward swimming organisms come from the deeper regions to feed at night. </p>
<p>The implications of these findings are yet to be explored in detail. But it looks like understanding mixing processes could help us prevent <a href="https://www.theguardian.com/uk-news/2021/oct/08/sewage-could-leave-windermere-lake-ecologically-dead">algal blooms</a> like those currently threatening Lake Windermere from developing, as these can be driven by weak mixing during summer that leaves sewage trapped in layers of the lake.</p><img src="https://counter.theconversation.com/content/169222/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Iestyn Woolway receives funding from the Natural Environment Research Council.</span></em></p><p class="fine-print"><em><span>John Harold Simpson received research funding from the Natural Environment Council from 1970-2015.</span></em></p><p class="fine-print"><em><span>Martin Austin receives funding from Engineering and Physical Sciences Research Council. </span></em></p>Studies of Lake Windermere show how organisms moving in lakes help keep water layers fresh and reduce greenhouse gas production.Iestyn Woolway, Research Fellow in Climate Science, University of ReadingJohn Harold Simpson, Professor Emeritus in Physical Oceanography, Bangor UniversityMartin Austin, Senior Lecturer in Coastal Dynamics, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1642272021-07-15T16:46:43Z2021-07-15T16:46:43ZExtreme heat waves are putting lakes and rivers in hot water this summer<figure><img src="https://images.theconversation.com/files/411299/original/file-20210714-21-1bygcs3.jpg?ixlib=rb-1.1.0&rect=36%2C80%2C4837%2C2917&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">River fish like trout swim close to the river surface as water temperatures rise.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Extreme heat waves have blanketed the <a href="https://www.washingtonpost.com/world/2021/06/30/climate-change-heat-politics/">Pacific Northwest, Siberia</a>, <a href="https://greekreporter.com/2021/06/30/heat-waves-greece-around-world-break-new-records/">Greece</a>, <a href="https://www.aljazeera.com/news/2021/7/1/interactive-mapping-hottest-temperatures-around-world">the Middle East</a>, <a href="https://www.telegraph.co.uk/global-health/climate-and-people/hotter-human-body-can-handle-pakistan-city-broils-worlds-highest/">Southeast Asia</a> and <a href="https://www.nytimes.com/2021/07/09/upshot/record-breaking-hot-weather-at-night-deaths.html">other regions</a> this summer, with <a href="https://www.bbc.com/news/world-us-canada-57788118">temperatures approaching</a> and exceeding 50 C.</p>
<p>As temperatures near outdoor survival thresholds, individuals who do not have easy access to air conditioning or cooling stations, or are <a href="https://www.theguardian.com/commentisfree/2021/jul/07/global-heating-climate-crisis-heat-two-classes">unable to flee</a>, may <a href="https://doi.org/10.1038/s41558-021-01058-x">succumb to heat waves</a>. </p>
<p>These <a href="https://doi.org/10.1073/pnas.1101766108">climate extremes are becoming more frequent</a>. But as tragic as they are to human health, they are only part of a larger climate catastrophe story — the wide-scale damage to the ecosystems that people depend upon, including agriculture, fisheries and freshwater.</p>
<p>Most wildlife cannot seek refuge from extreme heat. An estimated <a href="https://www.cbc.ca/news/canada/british-columbia/intertidal-animals-ubc-research-1.6090774">one billion marine animals may have perished</a> during the heatwave this past June in the Pacific Northwest alone.</p>
<h2>Fisheries in hot water</h2>
<p>Many people may perceive lakes and rivers to be refuges from unprecedented heat, but freshwater systems are no less sensitive. <a href="https://www.independent.co.uk/climate-change/news/alaska-heatwave-salmon-rivers-july-temperatures-climate-change-a9063461.html">Heat waves have killed thousands of fish in Alaska</a> as temperatures exceeded the lethal limit for coldwater fishes.</p>
<p>This year’s hot and dry summer could <a href="https://www.sacbee.com/news/california/water-and-drought/article252650328.html">collapse the salmon fishery in the Sacramento River in California</a>. In British Columbia and Yukon, salmon numbers have declined by as much as 90 per cent and have led the federal government to shut down <a href="https://www.timescolonist.com/sports/add-an-event/ottawa-to-close-about-60-per-cent-of-commercial-salmon-fisheries-to-conserve-stocks-1.24336891">60 per cent of the commercial and First Nations communal salmon fishery</a>. </p>
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Read more:
<a href="https://theconversation.com/how-drought-affects-freshwater-fish-109781">How drought affects freshwater fish</a>
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<p>Coldwater fish, such as trout and salmon, are being squeezed out of their cool, well-oxygenated, deep-water habitat. As water contains less oxygen at higher water temperatures, this forces the fish to move into nearshore regions. While these shallower waters may be better oxygenated, they are even warmer and may exceed thermal tolerances of coldwater species. </p>
<p>By the same token, invasive fishes such as smallmouth bass are thriving in warmer temperatures and displacing native Canadian fishes like walleye and lake trout.</p>
<h2>Water is on the move — too little and too much</h2>
<p>The combination of a warming climate, drought and human activities, including irrigation for agriculture, can have drastic consequences for both the quality and quantity of our freshwater supply — ultimately leading to shortages of potable water.</p>
<p>By the end of the century, <a href="https://doi.org/10.1038/s41561-018-0114-8">evaporation is projected to increase by 16 per cent globally</a>. Lakes closer to the equator, which are already experiencing the highest evaporation rates, are expected to experience the greatest increase. </p>
<p>In regions with seasonal ice cover, evaporation rates can increase with warmer air temperatures and when ice cover is shorter or lost completely. This essentially “lifts the lid” on a lake during winter and could potentially lead to year-round evaporation, accelerating the rate at which water is lost. Salts and nutrients are concentrated in the remaining water, leading to further decline in water quality. </p>
<figure class="align-center ">
<img alt="The dry bed of an evaporated pond in Arctic Canada." src="https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410843/original/file-20210712-23-jhxnd.jpeg?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">Beach Ridge Pond, from Ellesmere Island in Nunavut, now completely evaporates in the summer because of accelerated climate warming.</span>
<span class="attribution"><span class="source">(MSV Douglas)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Potable water in countries with limited freshwater are <a href="https://www.nationalgeographic.com/magazine/article/drying-lakes-climate-change-global-warming-drought">seeing their supply dwindle even further</a>, including the <a href="https://www.mentalfloss.com/article/56732/10-lakes-are-disappearing-or-already-gone">Aral Sea in Kazakhstan and Lake Chad in central Africa</a>. <a href="https://theconversation.com/lake-poopo-why-bolivias-second-largest-lake-disappeared-and-how-to-bring-it-back-152776">Lake Poopó was once the second-largest lake in Bolivia with an area of 3,000 square kilometres, but dried up completely in 2015</a>. Even in water-rich areas like the Arctic, <a href="https://doi.org/10.1073/pnas.0702777104">shallow ponds</a>, including some <a href="https://www.doi.org/10.1126/science.1108142">ponds formed when ice-rich permafrost thaws</a>, are already drying out. </p>
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<strong>
Read more:
<a href="https://theconversation.com/how-scientists-are-using-drones-to-lower-the-risk-of-catastrophic-flooding-from-large-glacial-lakes-158689">How scientists are using drones to lower the risk of catastrophic flooding from large glacial lakes</a>
</strong>
</em>
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<p>On the other hand, ice-dammed glacial lakes in both polar and alpine regions are sensitive to outburst floods as dams melt, potentially flooding downstream ecosystems and the communities that depend on them, including population-rich areas such as <a href="https://doi.org/10.1038/s41558-021-01028-3">in the Himalayas</a> and <a href="https://www.nature.com/articles/s41561-021-00686-4.epdf?sharing_token=dvnb89oERd0OajwLFZXscNRgN0jAjWel9jnR3ZoTv0NpVdznzVXpU0m-Rai-gGLEEEq67k5aPfFB5nX1DG8RWzIQ8JaW1ei3lTOobV6C9kc-cdxEn0U_fZkPVphxffsgbZHEr8tm8Fu_rFSvw3ED98_HmklXtjMtETMSzzRoYyM%3D">Andes</a>. Climate change is a crisis multiplier and threatens to make water scarcity or flooding an impending reality for increasingly more people.</p>
<h2>Algal blooms on the rise</h2>
<p>Warmer summers, coupled with <a href="https://doi.org/10.1139/facets-2020-0022">intense storms</a> that deliver large quantities of nutrients and pollutants in bursts, are creating the perfect conditions for <a href="https://doi.org/10.1038/s41586-019-1648-7">earlier, more frequent and intense algal blooms</a>. Harmful toxin-producing cyanobacteria (blue-green algae that frequently form floating surface blooms) can lead to mass mortality of fish and birds, as well as pose a serious health threat for cattle, pets, wildlife and humans.</p>
<p>In 2014, over half a million people could not use their water supply in Toledo, Ohio, because of a <a href="https://www.nationalgeographic.com/science/article/140804-harmful-algal-bloom-lake-erie-climate-change-science">toxic algal bloom in Lake Erie</a>. Lake Taihu, China, which <a href="https://doi.org/10.1007/s00267-009-9393-6">supplies water to 40 million people</a> often has blooms so large that they can be <a href="https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=31.23217880603803&lng=120.10940551757812&zoom%22%22">detected from space</a> and leave millions of people in a drinking water supply crisis. </p>
<figure class="align-center ">
<img alt="A lake near Parry Sound, Ont., covered in algal bloom." src="https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410844/original/file-20210712-70646-12ggbkz.jpeg?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">An algal bloom in a lake near Parry Sound, Ont., located on the Canadian Shield.</span>
<span class="attribution"><span class="source">(Andrew Paterson/Ontario Ministry of the Environment, Conservation and Parks)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In Ontario, there are now <a href="https://doi.org/10.1007/s10933-019-00074-4">reports of algal blooms</a> in formerly pristine northern lakes occurring as late as November. Study after study now links warmer conditions and the associated lake changes as important contributing factors to toxic blooms.</p>
<h2>Rapid change requires rapid responses</h2>
<p>Climatic extremes are now occurring more frequently and with greater intensity than were <a href="https://theconversation.com/just-how-hot-will-it-get-this-century-latest-climate-models-suggest-it-could-be-worse-than-we-thought-137281">predicted by even the most pessimistic climate models</a>. We are already crossing ecosystem thresholds and tipping points that were not even projected to occur until the end of this century. </p>
<p>Climatic extremes will not appear gradually, but impacts will be felt quickly and often without warning, leaving little time for adaptation. We need to immediately <a href="https://www.cbc.ca/news/canada/lytton-fire-climate-emergency-preparedness-1.6096370">develop and implement evidence-based climate adaptation plans</a>, so that we are prepared for the inevitable emergencies already underway, including massive wildfires, coastal and <a href="https://www.reuters.com/business/environment/thirty-missing-germany-house-collapses-heavy-rain-media-2021-07-15/">local flooding</a>, disruption of food supplies and freshwater shortages.</p>
<p>The apocalyptic future, once portrayed only in books and movies, is becoming our reality and the time for assessing our options is running out. Numerous studies have shown the benefits of reducing greenhouse gas emissions. Human innovation and originality, coupled with a sense of urgency, are required to lessen future impacts.</p>
<p>Without mitigation efforts, we must prepare for the fallout of the developing climate catastrophe and protect our citizens and ecosystems.</p><img src="https://counter.theconversation.com/content/164227/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sapna Sharma receives funding from NSERC, Ontario Ministry of Economic Development and Innovation, Ontario Ministry of Environment, Conservation and Parks, Genome Canada, and the York University Research Chair Program. She is affiliated with the Royal Canadian Institute for Science. </span></em></p><p class="fine-print"><em><span>John P. Smol receives funding from NSERC and the Canada Research Chairs program.</span></em></p><p class="fine-print"><em><span>Iestyn Woolway 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 growing frequency of climate extremes affected human health and caused wide-scale damages to the ecosystems that people depend upon, including agriculture, fisheries and freshwater.Sapna Sharma, Associate Professor and York University Research Chair in Global Change Biology, York University, CanadaIestyn Woolway, Research Fellow, Climate Office, European Space AgencyJohn P. Smol, Distinguished University Professor and Canada Research Chair in Environmental Change, Queen's University, OntarioLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1561482021-06-07T13:53:55Z2021-06-07T13:53:55ZClimate change: world’s lakes are in hot water – threatening rare wildlife<figure><img src="https://images.theconversation.com/files/404829/original/file-20210607-23-1ael54s.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6275%2C3902&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/pink-flamingos-during-brilliant-sunset-1060482575">Jdross75/Shutterstock</a></span></figcaption></figure><p>The Earth’s surface is splotched with 117 million lakes. Some are scarcely more than ponds, while others are so big they can be seen from space. At 395 miles long, 49 miles wide and just over 1 mile deep, <a href="https://theconversation.com/lake-baikal-incredible-ecosystem-threatened-by-mongolian-dam-and-pipeline-40025">Lake Baikal in Siberia</a> is one of the world’s largest and it’s home to 2,500 species, including the Baikal seal – Earth’s only species of freshwater seal. </p>
<p>Lakes and rivers occupy just 1% of the Earth’s surface but are incredible hotspots for biodiversity, sheltering <a href="https://bioone.org/journals/journal-of-the-north-american-benthological-society/volume-29/issue-1/08-171.1/Freshwater-biodiversity-conservation-recent-progress-and-future-challenges/10.1899/08-171.1.full">10% of all species globally</a>. Particularly in older and deeper lakes, life has had millions of years to evolve and adapt to the peculiarities of that habitat, giving rise to unique forms. But since 1970, numbers of freshwater vertebrates, including birds, fish, amphibians, reptiles and mammals, have declined by <a href="https://c402277.ssl.cf1.rackcdn.com/publications/1187/files/original/LPR2018_Full_Report_Spreads.pdf">a staggering 83%</a> through the extraction of lake water, pollution, invasive species and disease. Now, climate change threatens to drive even deeper losses.</p>
<p>Lake heatwaves – when surface water temperatures rise above their average for longer than five days – are a relatively new phenomenon. But by the end of this century, heatwaves could last between <a href="https://www.carbonbrief.org/lake-heatwaves-will-be-hotter-and-longer-by-the-end-of-the-century">three and 12 times longer</a> and become 0.3°C to 1.7°C hotter. In some places, particularly near the equator, lakes may enter a permanent heatwave state. Smaller lakes may shrink or disappear entirely, along with the wildlife they contain, while deeper lakes will face less intense but longer heatwaves.</p>
<p><a href="https://www.nature.com/articles/s41586-021-03550-y">In a new study</a>, researchers examined 393 lakes worldwide between 1981 and 2017 and found their temperatures rose by 0.39°C every decade, while dissolved oxygen fell by 5% at the surface and 19% in the depths. It’s in these cooler, deeper parts of lakes where trout, burbot and salmon usually thrive thanks to sufficient oxygen, especially in the summer. Largely due to warming air temperatures, 68% of the lakes in the study had lost this important niche to rising temperatures and falling oxygen levels.</p>
<p>So what do these changes mean for the other forms of life that call lakes home?</p>
<h2>How lake life will change</h2>
<p>Most organisms that live in lakes can only thrive in water with just the right temperature and concentration of nutrients and oxygen. Warmer lakes hold less oxygen and lose more water through evaporation, forcing species to live in saltier and less oxygenated habitats. </p>
<p>Things won’t be easy for species which live above the water for most of their lives either. Dragonflies are a common sight flitting among the reeds on the lake side. They lay their eggs in the shallows, but as lakes are lowered or dry out during more frequent and severe heatwaves, this protection is lost. Those larvae which survive are likely to emerge early, when food and habitat <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/een.12175">may be lacking</a>.</p>
<p>Climate change will shift the types of organisms we find in lakes. Cold water fish, such as trout and salmon, need cooler temperatures and higher oxygen concentrations than warm water species such as largemouth bass and white perch. One cold-loving species, Arctic char, could vanish from <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3535054/">73% of its Swedish range</a> by 2100 just as a result of warming. Meanwhile, rising temperatures could mean parasites that infect fish grow <a href="https://www.researchgate.net/profile/David-Marcogliese/publication/23285586_The_impact_of_climate_change_on_the_parasites_and_infectious_diseases_of_aquatic_animals/links/00b7d529392e96d406000000/The-impact-of-climate-change-on-the-parasites-and-infectious-diseases-of-aquatic-animals.pdf">faster and larger</a>. In one study, parasitic worms infecting stickleback fish <a href="https://www.nationalgeographic.com/science/article/tapeworm-stickleback-parasite-hea">grew four times faster</a> in water at 20°C compared to 15°C.</p>
<p>Heatwaves could accelerate the spread and size of pathogens in fish, with huge consequences for the aquaculture industry and wild populations. Human diseases, transmitted by freshwater organisms, may also increase. <a href="https://www.cdc.gov/parasites/naegleria/general.html"><em>Naegleria fowleri</em></a> is a lake parasite that flourishes in warmer temperatures. Known as the brain-eating amoeba, this microbe can cause fatal meningoencephalitis if it enters the body through the nose. Prolonged periods when lake waters remain warmer than average could see this parasite expand into more temperate waters.</p>
<p>Since warmer surface waters hold more nutrients, climate change could cause an explosion in the number of microscopic algae that live in lakes. These microorganisms are the base of the food web and the foundation of life in these habitats. But this isn’t the good news it seems. When nutrients are abundant, huge quantities of these algae can form a thick green (or sometimes red) blanket on the lake surface. These algal blooms not only look unsightly, they often produce harmful toxins.</p>
<p>Heatwaves are increasing the frequency of <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2486.2007.01510.x">harmful algal blooms</a> and causing mass mortality events where thousands of animals die in a few days. Algal blooms block out the light and suffocate fish, either by crashing oxygen levels or clogging up their gills. A 100 metre-wide, 15cm-deep algal bloom in Loch Leven in Scotland in 1992 killed 1,000 brown trout <a href="https://www.researchgate.net/profile/H-Rodger/publication/229574439_Cyanobacterial_blue-green_algal_bloom_associated_pathology_in_brown_trout_Salmo_trutta_L_in_Loch_Leven_Scotland/links/59da43480f7e9b12b36d845c/Cyanobacterial-blue-green-algal-bloom-associated-pathology-in-brown-trout-Salmo-trutta-L-in-Loch-Leven-Scotland.pdf">over 24 hours</a>.</p>
<figure class="align-center ">
<img alt="Six dead fish float in algae-choked water." src="https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/404831/original/file-20210607-28372-lg24vv.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">Lake algal blooms are likely to be more frequent and severe as Earth warms.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dead-fish-floating-algae-bloom-pollution-1732509536">O Partime Photo/Shutterstock</a></span>
</figcaption>
</figure>
<p>Unlike those living elsewhere, most lake animals cannot simply move to another habitat once their lake becomes uninhabitable. But even migratory species will suffer. In August 2004, 15,000 flamingos died on a lake in Tanzania after consuming toxins <a href="https://www.sciencedirect.com/science/article/pii/S1568988305001101?casa_token=8biWViaxpvwAAAAA:be-RaUvehMkvkM6Lgn2SmWHR3RSfBv8Lz_qAwIcLWIfXGzP49koxROsu-ptZbRWM583jYugziGc">produced by algal blooms</a>.</p>
<p>As heatwaves proliferate and oxygen levels decline, <a href="https://www.nature.com/articles/s41558-019-0520-y">mass fish die-offs</a> are predicted to double from the 2040s in lakes in the northern hemisphere and increase fourfold in the southern hemisphere from the 2080s onwards. Without immediate action to curb emissions and slow climate change, many of the world’s lakes are on course for a sweltering, breathless and lifeless future.</p><img src="https://counter.theconversation.com/content/156148/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antonia Law 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 lives of one in ten of Earth’s species are connected to lakes and their tributaries.Antonia Law, Lecturer in Physical Geography, Keele UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1590922021-04-19T12:28:39Z2021-04-19T12:28:39ZInterstate water wars are heating up along with the climate<figure><img src="https://images.theconversation.com/files/395345/original/file-20210415-20-oo9nth.jpg?ixlib=rb-1.1.0&rect=13%2C4%2C2925%2C1912&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Aerial view of Lake Powell on the Colorado River along the Arizona-Utah border.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/ColoradoRiverManagement/d12a55f700714682baf7468c24e4aea4/photo">AP Photo/John Antczak</a></span></figcaption></figure><p>Interstate water disputes are as American as apple pie. States often think a neighboring state is using more than its fair share from a river, lake or aquifer that crosses borders. </p>
<p>Currently the U.S. Supreme Court has on its docket a case between <a href="https://www.scotusblog.com/case-files/cases/texas-v-new-mexico-and-colorado/">Texas, New Mexico and Colorado</a> and another one between <a href="https://www.scotusblog.com/case-files/cases/mississippi-v-tennessee/">Mississippi and Tennessee</a>. The court has already ruled this term on cases pitting <a href="https://www.oyez.org/cases/2020/65-orig">Texas against New Mexico</a> and <a href="https://www.law.cornell.edu/supremecourt/text/20O0142">Florida against Georgia</a>. </p>
<p>Climate stresses are raising the stakes. Rising temperatures require farmers to use more water to grow the same amount of crops. Prolonged and severe droughts decrease available supplies. Wildfires are <a href="https://theconversation.com/the-year-the-west-was-burning-how-the-2020-wildfire-season-got-so-extreme-148804">burning hotter and lasting longer</a>. Fires bake the soil, reducing forests’ ability to hold water, increasing evaporation from barren land and compromising water supplies.</p>
<p>As a longtime <a href="https://robertglennon.net/">observer of interstate water negotiations</a>, I see a basic problem: In some cases, more water rights exist on paper than as wet water – even before factoring in shortages caused by climate change and other stresses. In my view, states should put at least as much effort into reducing water use as they do into litigation, because there are no guaranteed winners in water lawsuits.</p>
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<h2>Dry times in the West</h2>
<p>The situation is most urgent in California and the Southwest, which currently face “<a href="https://droughtmonitor.unl.edu/">extreme or exceptional” drought conditions</a>. California’s reservoirs are <a href="https://www.bloomberg.com/news/articles/2021-04-01/california-reservoirs-are-half-empty-recalling-historic-drought?sref=Hjm5biAW">half-empty</a> at the end of the rainy season. The Sierra snowpack sits at <a href="https://www.kxan.com/weather/spring-2021-nasty-drought-in-forecast-for-much-of-us/">60% of normal</a>. In March 2021, federal and state agencies that oversee California’s Central Valley Project and State Water Project – regional water systems that each cover hundreds of miles – issued “<a href="https://www.sacbee.com/news/california/water-and-drought/article250145884.html">remarkably bleak warnings</a>” about cutbacks to farmers’ water allocations.</p>
<p>The Colorado River Basin is mired in a <a href="https://www.doi.gov/water/owdi.cr.drought/en/">drought that began in 2000</a>. Experts disagree as to <a href="https://theconversation.com/western-states-buy-time-with-a-7-year-colorado-river-drought-plan-but-face-a-hotter-drier-future-119448">how long it could last</a>. What’s certain is that the “<a href="https://www.usbr.gov/lc/region/pao/lawofrvr.html">Law of the River</a>” – the body of rules, regulations and laws governing the Colorado River – has allocated <a href="https://www.grandcanyontrust.org/advocatemag/spring-summer-2016/problem-math">more water to the states than the river reliably provides</a>.</p>
<p>The <a href="https://www.usbr.gov/lc/region/pao/pdfiles/crcompct.pdf">1922 Colorado River Compact</a> allocated 7.5 million acre-feet (one acre-foot is roughly 325,000 gallons) to California, Nevada and Arizona, and another 7.5 million acre-feet to Utah, Wyoming, Colorado and New Mexico. A treaty with Mexico secured that country 1.5 million acre-feet, for a total of 16.5 million acre-feet. However, estimates based on <a href="https://www.environmentalscience.org/dendrochronology-tree-rings-tell-us">tree ring analysis</a> have determined that the actual yearly flow of the river over the last 1,200 years is <a href="https://www.doi.gov/water/owdi.cr.drought/treeringdata/index.html">roughly 14.6 million acre-feet</a>. </p>
<p>The inevitable train wreck has not yet happened, for two reasons. First, Lakes <a href="https://en.wikipedia.org/wiki/Lake_Mead">Mead</a> and <a href="https://en.wikipedia.org/wiki/Lake_Powell">Powell</a> – the two largest reservoirs on the Colorado – can hold a combined 56 million acre-feet, roughly four times the river’s annual flow. </p>
<p>But diversions and increased evaporation due to drought are <a href="https://www.crwua.org/assets/downloads/2020-annual-conference/CRWUA-Federal-Friday-Presentation-2020-System-Status.pdf">reducing water levels in the reservoirs</a>. As of Dec. 16, 2020, both lakes were less than half full.</p>
<p>Second, the Upper Basin states – Utah, Wyoming, Colorado and New Mexico – have never used their full allotment. Now, however, they want to use more water. Wyoming has several new dams on the drawing board. So does Colorado, which is also planning a new diversion from the headwaters of the Colorado River to Denver and other cities on the Rocky Mountains’ east slope. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Much of the U.S. Southwest and California are in extreme or exceptional drought." src="https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395354/original/file-20210415-14-1e6n98a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Drought conditions in the continental U.S. on April 13, 2021.</span>
<span class="attribution"><a class="source" href="https://droughtmonitor.unl.edu/data/png/20210413/20210413_conus_text.png">U.S. Drought Monitor</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Utah stakes a claim</h2>
<p>The most controversial proposal comes from one of the nation’s fastest-growing areas: St. George, Utah, home to approximately 90,000 residents and lots of golf courses. St. George has <a href="https://www.bloomberg.com/news/articles/2018-05-18/st-george-utah-is-booming-and-guzzling-water">very high water consumption rates and very low water prices</a>. The city is proposing to augment its water supply with a <a href="https://blogs.scientificamerican.com/observations/john-wesley-powell-great-explorer-of-the-american-west/">140-mile pipeline from Lake Powell</a>, which would carry 86,000 acre-feet per year.</p>
<p>Truth be told, that’s not a lot of water, and it would not exceed Utah’s unused allocation from the Colorado River. But the six other Colorado River Basin states have protested as though St. George were asking for their firstborn child. </p>
<p>In a joint letter dated Sept. 8, 2020, the other states implored the Interior Department to refrain from issuing a final environmental review of the pipeline until all seven states could “<a href="https://www.scribd.com/document/475439148/Six-States-Letter-to-SOI-Sep-8-2020#from_embed">reach consensus regarding legal and operational concerns</a>.” The letter explicitly threatened a high “probability of <a href="https://www.scribd.com/document/475439148/Six-States-Letter-to-SOI-Sep-8-2020#from_embed">multi-year litigation</a>.”</p>
<p>Utah blinked. Having earlier insisted on an expedited pipeline review, the state asked federal officials on Sept. 24, 2020 <a href="https://www.sltrib.com/news/environment/2020/09/24/after-insisting-expedited/">to delay a decision</a>. But Utah has not given up: In March 2021, Gov. Spencer Cox signed a bill creating a <a href="https://www.sltrib.com/news/environment/2021/03/04/utah-senate-backs-new/">Colorado River Authority of Utah</a>, armed with a US$9 million legal defense fund, to protect Utah’s share of Colorado River water. One observer predicted “<a href="https://tucson.com/news/local/colorado-river-outlook-darkens-dramatically-in-new-study/article_15e0185d-60d7-597d-ba7f-366b8e69920e.html">huge, huge litigation</a>.”</p>
<p>How huge could it be? In 1930, Arizona sued California in an <a href="https://en.wikipedia.org/wiki/Arizona_v._California">epic battle</a> that did not end until 2006. Arizona prevailed by finally securing a <a href="https://www.usbr.gov/lc/region/pao/pdfiles/scconsolidateddecree2006.pdf">fixed allocation from the water apportioned to California, Nevada and Arizona</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rWpui1P9cAY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Southwest Utah’s claim to Colorado River water is sparking conflict with other western states.</span></figcaption>
</figure>
<h2>Litigation or conservation</h2>
<p>Before Utah takes the precipitous step of appealing to the Supreme Court under the court’s original jurisdiction over disputes between states, it might explore other solutions. Water conservation and reuse make obvious sense in St. George, where per-person water consumption is <a href="https://islandpress.org/books/unquenchable">among the nation’s highest</a>.</p>
<p>St. George could emulate its neighbor, Las Vegas, which has paid residents up to $3 per square foot to <a href="https://apnews.com/article/1d38cf067394498fac0f9f623892eab6">rip out lawns</a> and replace them with native desert landscaping. In April 2021 Las Vegas went further, asking the Nevada Legislature to <a href="https://tucson.com/news/state-and-regional/las-vegas-pushes-to-become-first-to-ban-ornamental-grass/article_1771f7c0-dde6-53e1-9ccc-3c27e0729eb6.html">outlaw ornamental grass</a>. </p>
<p>The Southern Nevada Water Authority estimates that the Las Vegas metropolitan area has eight square miles of “nonfunctional turf” – grass that no one ever walks on except the person who cuts it. Removing it would <a href="https://tucson.com/news/state-and-regional/las-vegas-pushes-to-become-first-to-ban-ornamental-grass/article_1771f7c0-dde6-53e1-9ccc-3c27e0729eb6.html">reduce the region’s water consumption by 15%</a>. </p>
<p>Water rights litigation is fraught with uncertainty. Just ask Florida, which thought it had a strong case that Georgia’s water diversions from the Apalachicola-Chattahoochee-Flint River Basin were harming its oyster fishery downstream. </p>
<p>That case extended over 20 years before the U.S. Supreme Court ended the final chapter in April 2021. The court used a procedural rule that places the burden on plaintiffs to provide “clear and convincing evidence.” Florida <a href="https://www.law.cornell.edu/supremecourt/text/20O0142">failed to convince the court</a>, and walked away with nothing.</p><img src="https://counter.theconversation.com/content/159092/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Glennon received funding from the National Science Foundation in the 1990s and 2000s.</span></em></p>The Supreme Court recently dealt defeat to Florida in its 20-year legal battle with Georgia over river water. Other interstate water contests loom, but there are no sure winners in these lawsuits.Robert Glennon, Regents Professor and Morris K. Udall Professor of Law & Public Policy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1579872021-04-13T11:29:03Z2021-04-13T11:29:03ZFloating solar farms could cool down lakes threatened by climate change<figure><img src="https://images.theconversation.com/files/394308/original/file-20210409-19-7tdcx3.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4031%2C2268&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The future of solar energy?</span> <span class="attribution"><span class="source">Giles Exley</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Solar power is now the <a href="https://www.carbonbrief.org/solar-is-now-cheapest-electricity-in-history-confirms-iea">cheapest source of electricity in history</a>, according to a <a href="https://webstore.iea.org/world-energy-outlook-2020">2020 report</a> by the International Energy Agency. But there’s something holding this clean energy powerhouse back: space. Unlike fossil fuel power stations, solar farms need a lot of room to generate enough electricity to keep up with demand. Most solar farms are composed of ground-mounted panels that <a href="https://www.nature.com/articles/s41893-019-0309-z">take up land</a> that could be used to grow food or provide habitat for wildlife.</p>
<p>Although electricity and water don’t usually mix, a growing number of <a href="https://www.mdpi.com/2071-1050/12/19/8154">floating solar farms</a> are being deployed worldwide. Floating solar panels on a lake or reservoir might sound like an accident waiting to happen, but recent studies have shown the technology <a href="https://www.sciencedirect.com/science/article/pii/S0038092X20311853">generates more electricity</a> compared with rooftop or ground-mounted solar installations. This is thanks to the cooling effect of the water beneath the panels, which can boost how efficiently these systems generate electricity by as much as <a href="https://ietresearch.onlinelibrary.wiley.com/doi/10.1049/iet-rpg.2015.0120">12.5%</a>.</p>
<p>That said, lakes and reservoirs are already very important for people and the planet. While these freshwater bodies cover less than 1% of Earth’s surface, they nurture almost <a href="https://onlinelibrary.wiley.com/doi/abs/10.1017/S1464793105006950">6% of its biodiversity</a> and provide drinking water and crop irrigation that’s vital to billions of people. Worryingly, <a href="https://www.nature.com/articles/s43017-020-0067-5">climate change</a> has raised the surface temperatures of lakes globally by an average of <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL066235">0.34°C per decade since 1985</a>, encouraging <a href="https://science.sciencemag.org/content/320/5872/57?ijkey=42eb549c22938ef3ce5a0daec395d340e1bd6748&amp;keytype2=tf_ipsecsha">toxic algal blooms</a>, <a href="https://www.nature.com/articles/s41561-018-0114-8">lowering water levels</a> and <a href="https://www.nature.com/articles/s41561-019-0322-x">preventing water mixing</a> between the distinct layers which naturally form in larger and deeper lakes, starving the depths of oxygen.</p>
<p>In the rush to decarbonise energy in order to slow global warming, might turning to floating solar farms simply add to the strain on the world’s precious freshwater reserves? Remarkably, in <a href="https://www.sciencedirect.com/science/article/pii/S0038092X2100116X">new research</a>, we found that carefully designed floating solar farms could actually reduce the threats posed by climate change to lakes and reservoirs.</p>
<h2>A buffer against warming</h2>
<p>Along with colleagues, I used a computer model to simulate how floating solar farms are likely to affect lake water temperatures. Our simulations are based on Windermere, the largest lake in England and one of the most <a href="https://www.ceh.ac.uk/our-science/monitoring-site/lake-observatories">well-studied</a> lakes in the world.</p>
<p>Floating solar farms reduce how much wind and sunlight reaches the lake’s surface, changing many of the processes that occur within. As each floating solar farm has a different design, we ran simulations to see how lake temperatures changed with over 10,000 unique combinations of wind speed and solar radiation.</p>
<figure class="align-center ">
<img alt="A raft of solar panels held in place on a reservoir's surface with a mooring rope." src="https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/394010/original/file-20210408-23-16423l.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">A floating solar farm generating electricity for a water treatment works at a reservoir in north-west England.</span>
<span class="attribution"><span class="source">Giles Exley</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0038092X2100116X">Our results</a> suggest that the changes to water temperatures caused by floating solar farms could be as big as climate change itself, only in the opposite direction.</p>
<p>A floating solar farm that reduces wind speed and solar radiation by 10% across the entire lake could offset a decade of warming from climate change. Designs that shaded the lake more than sheltered it, by reducing sunlight more than wind, had the greatest cooling effect. Evaporation fell and the lake was mixed more frequently, which helps oxygenate the deeper water.</p>
<p>These effects might vary depending on a lake’s <a href="https://iopscience.iop.org/article/10.1088/1748-9326/abbf7b">depth, surface area and location</a>. But ecological processes in lakes are most affected by wind speed and sunlight, which is what our simulations focused on.</p>
<h2>Global potential</h2>
<p>While most of our simulations indicated a win-win for lakes and floating solar farms, some suggested undesirable side effects. In a small number of simulations, we found that floating solar farms that reduced wind speed at the lake’s surface more than they reduced sunlight might actually mimic or amplify the effects of climate change, increasing how long deeper lakes remain stratified. Thankfully, we think the careful design of floating solar farms should reduce these risks.</p>
<p>Floating solar power has grown more than a <a href="https://www.sciencedirect.com/science/article/pii/S2211285520306893">hundredfold</a> in the past five years, reaching <a href="https://www.pv-magazine.com/2020/09/22/floating-solar-pv-gains-global-momentum/">2.6 gigawatts of installed capacity</a> across 35 countries. If just 1% of the surface area of all human-made water bodies (which are easier to access and typically less ecologically sensitive than natural lakes) was covered by floating solar panels, <a href="https://openknowledge.worldbank.org/bitstream/handle/10986/31880/Floating-Solar-Market-Report.pdf?sequence=1&isAllowed=y">it could generate 400 gigawatts</a> – enough electricity to power 44 billion LED light bulbs for a year.</p>
<p>Floating solar is likely to make an important contribution to the decarbonisation of the world’s energy supplies. In a stroke of serendipity, our research suggests this could have the added benefit of offsetting part of the damage to lakes caused by rising temperatures.</p>
<p>Still, our simulations only covered the physical effects of floating solar, while other questions remain unresolved. How would floating solar farms interact with other lake uses, such as sport or aquaculture? How would the wildlife sharing the lake fare? And which lakes are best suited to hosting a floating solar farm? The work to fully understand the potential of this technology is only just beginning.</p><img src="https://counter.theconversation.com/content/157987/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Giles Exley receives funding from NERC and United Utilities for their Envision DTP PhD studentship.</span></em></p>Earth’s floating solar power capacity has grown one-hundredfold in the last five years.Giles Exley, Associate Lecturer of Energy and Environment, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.