tag:theconversation.com,2011:/global/topics/seagrass-meadows-49853/articlesSeagrass meadows – The Conversation2023-06-20T16:00:02Ztag:theconversation.com,2011:article/2070642023-06-20T16:00:02Z2023-06-20T16:00:02ZUnprecedented marine heatwave underlines the urgency to clean up UK rivers and coasts<figure><img src="https://images.theconversation.com/files/532920/original/file-20230620-17-f21hil.jpg?ixlib=rb-1.1.0&rect=1386%2C0%2C3138%2C2924&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Seagrass meadows are an important part of the UK’s marine environment.</span> <span class="attribution"><span class="source">Benjamin Jones/Project Seagrass</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Thousands of people took to the UK’s seas and rivers recently in a <a href="https://www.reuters.com/world/uk/sick-sewage-britons-protest-water-companies-pollution-2023-05-20/">nationwide “paddle-out” protest</a> to demand an end to sewage spilling into the country’s waterways. The campaigners were largely concerned about the consequences of this filth for human health and nature.</p>
<p>But as the UK’s coastal seas boil under what is an <a href="https://www.theguardian.com/environment/2023/jun/19/marine-heatwave-uk-irish-coasts-threat-oysters-fish-high-temperatures">unprecedented marine heatwave</a>, these calls have new urgency. At the time of writing, some areas off the coast of England are up to 5°C warmer than usual.</p>
<p>The degradation of the UK’s rivers and coasts caused by pollution, coupled with the impact of marine heatwaves, poses a threat to the future of a vital coastal plant species called seagrass. </p>
<p>Seagrasses are plants that have adapted to live in the ocean, forming vast meadows that often span hundreds of hectares. These meadows provide habitats for marine wildlife and nurseries for commercially important species such as Atlantic cod. They also trap carbon from our atmosphere, help reduce coastal erosion and even filter <a href="https://link.springer.com/article/10.1007/s00227-021-03963-3">harmful bacteria from seawater</a>. </p>
<p>But unlike humans, <a href="https://www.sciencedirect.com/science/article/abs/pii/S1385110198000045#:%7E:text=In%20low-light%20environments%2C%20the%20respiring%20below-ground%20biomass%20%28which,and%20rhizomes%20may%20undermine%20plant%20vitality%20as%20well.">plants cannot control their body heat</a>. So higher seawater temperatures lead to increased respiration rates (the process living things use to create energy to live and grow) and a greater need for food.</p>
<p>A higher respiration rate is not necessarily a problem for seagrass if it has lots of light to photosynthesise effectively. The problem is that light is often limited in polluted waterways.</p>
<p>Stopping the flow of pollution into our rivers is no longer a luxury for another day, but an urgent necessity. Failing to clean up our water systems now will result in the loss of marine and aquatic life, undermining the functioning of our natural world.</p>
<h2>Algal growth</h2>
<p>Seagrasses also need a supply of nutrients like nitrate and phosphate, without which they will be unable to grow. In UK waterways, the discharge of sewage and farming waste into rivers and streams, and the <a href="https://www.frontiersin.org/articles/10.3389/fpls.2018.00133/full">excessive use of fertilisers</a> on the land contributes to elevated nutrient levels. However, these increased nutrient levels stimulate the growth of various types of algae in seawater, including those in the water, on seagrass leaves and on sediments. </p>
<p>This competition for nutrients puts seagrass at a disadvantage. Seagrasses primarily extract nutrients directly from the sediment, while algae can access them in the water more effectively.</p>
<p>As nutrient concentrations rise, algae populations continue to increase and form extensive blooms. The proliferation of algae turns the water green, covers the seagrass leaves and smothers the habitat. This overload of algae prevents seagrass from photosynthesising at such a rapid rate.</p>
<p>During a marine heatwave, seagrass experiences elevated respiration rates, which increases their need for light. In clear and healthy water, seagrasses respond by raising their photosynthetic rate to meet their additional energy requirements. However, when the water becomes overwhelmed by excessive algae growth, seagrass struggles to keep pace and eventually deteriorates.</p>
<figure class="align-center ">
<img alt="Seagrass covered in algae." src="https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532784/original/file-20230619-32911-4a5amn.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Seagrass smothered in algae in a lagoon in North Wales.</span>
<span class="attribution"><span class="source">Richard Unsworth/Project Seagrass</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Seagrass is suffocating</h2>
<p>The UK’s waterways and coastal seas are some of the most heavily polluted in Europe. Over 75% of the country’s rivers and streams <a href="https://www.newscientist.com/article/dn25737-the-most-polluted-rivers-and-streams-in-europe/">contain levels of organic pollutants</a> that are either lethal to aquatic life or have the potential to cause chronic harm. </p>
<p>However, nutrient pollution affects seagrass far beyond the boundaries of the UK. In 2021, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0258898">one study</a> estimated that 88% of seagrass meadows worldwide are exposed to nutrient inputs from wastewater.</p>
<p>Over the past two years, we’ve been documenting the health of seagrass meadows around the UK at <a href="https://www.projectseagrass.org/">Project Seagrass</a> (a marine conservation charity dedicated to saving the world’s seagrass) and <a href="https://www.swansea.ac.uk">Swansea University</a>. This research adds to a database initially <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.150596">published in 2016</a>. </p>
<p>Despite being located in <a href="https://www.gov.uk/guidance/marine-protected-areas-mpas#:%7E:text=MPAs%20are%20areas%20of%20the,damage%20caused%20by%20human%20activities.">marine protected areas</a>, most of the seagrass meadows we have studied are in “poor” condition. The levels of nitrogen recorded in these meadows are up to 75% higher than the global average. </p>
<p>By analysing seagrass leaves for nutrients, including nitrogen and a stable isotope of nitrogen called <sup>15</sup>N, we can identify the sources of these nutrients. Notably, sewage and livestock waste exhibit higher levels of <sup>15</sup>N compared to other nutrient sources. These results support our suspicion that the excess nitrogen found in seagrass primarily originates from sewage discharges and nutrients running off farmland.</p>
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<a href="https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A healthy seagrass meadow." src="https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532886/original/file-20230620-23-3odps6.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">Healthy seagrass meadows can reduce water pollution by sucking up nutrients and harmful bacteria.</span>
<span class="attribution"><span class="source">Benjamin Jones/Project Seagrass</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Costly pollution</h2>
<p>Interestingly, seagrass meadows can also play a crucial role in controlling nutrient pollution. Research has demonstrated the significant financial value of seagrass meadows in terms of their capacity to absorb and store nutrients. </p>
<p>For instance, a study in Sweden observed that the <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.3658">loss of 1,000 hectares of seagrass</a> over a 20-year period resulted in the release of 60,000 Mg of nitrogen back into the environment. This nitrogen release was more than three times the annual nitrogen load carried by rivers to Sweden’s north-west coastline.</p>
<p>The economic cost associated with this nitrogen release was estimated to be over US$140 million (£110 million). This calculation accounted for the expense required to meet the nitrogen reduction targets set by the <a href="https://water.europa.eu/freshwater/europe-freshwater/water-framework-directive">EU Water Framework Directive</a>, which includes things like the cost of building new wastewater treatment plants.</p>
<p>The loss of seagrass due to more intense marine heatwaves could exacerbate the ongoing deterioration of European waters. In our view, addressing water pollution, specifically from fertilisers and sewage, is just as urgent as tackling the climate and biodiversity crises.</p>
<p>Although we cannot accurately predict the intensity, duration and location of severe marine heatwaves, it seems that they are becoming more frequent as our climate system collapses. The only line of defence for the natural world against the rapidly changing climate is to make species and habitats more able to resist and recover from extreme events. This will require a fundamental change in the polluting practices that currently suffocate aquatic environments.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Richard K.F. Unsworth receives funding from the Natural Environment Research Council (UK). He is also Chief Scientific Officer for the marine conservation charity Project Seagrass.</span></em></p><p class="fine-print"><em><span>Benjamin L.H. Jones is Chief Conservation Officer for the marine conservation charity Project Seagrass. He is also president of the World Seagrass Association.</span></em></p>Seagrasses need light to remain resilient to marine heatwaves – water pollution disrupts that balance.Richard K.F. Unsworth, Associate professor in marine biology, Swansea UniversityBenjamin L.H. Jones, Chief Conservation Officer, Project Seagrass & Postdoctoral Associate, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1986262023-02-16T17:21:34Z2023-02-16T17:21:34ZTropical seagrass meadows are sand factories that can help defend coral reef islands from sea-level rise<figure><img src="https://images.theconversation.com/files/507827/original/file-20230202-20-iwyq0q.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5991%2C3988&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/shallow-seagrass-meadow-surrounds-tropical-island-1184202124">Ethan Daniels/Shutterstock</a></span></figcaption></figure><p>Seagrasses are flowering plants that form dense underwater meadows in coastal waters <a href="https://www.sciencedirect.com/science/article/pii/S002209810700305X?casa_token=a3O4U_oCNVEAAAAA:0pzHeTdFrjdLKCP4MyW1rbNyi0_J6cDrGcZkgtSDCVZ7HUhuf8_Up9Nca2nipymKAY2bRc9ygg">worldwide</a>, from the frigid seas of the Arctic to the warm shallows of the Caribbean. These meadows provide a <a href="https://docs.niwa.co.nz/library/public/NZAEBR-137.pdf">refuge</a> for young fish, food for grazing sea turtles and manatees, and help to slow climate change by absorbing carbon from the atmosphere up to <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/110004?casa_token=xVPsw9mgHHUAAAAA%3A-Sz2X6atZTjTAaHYxTSFrpnOycA04PDcsYztj-3ONSym0E2CqST_jtnWjFb7qipAFdJoUl0AE2OcVg">35 times faster</a> than rainforests.</p>
<p>In <a href="https://www.nature.com/articles/s43247-023-00675-y">a new study</a>, we discovered another reason to preserve the world’s remaining seagrass meadows: they can build and maintain coral reef islands.</p>
<p>Throughout the tropics, the breakdown of shells and skeletons belonging to organisms living on coral reefs has produced enough sand to form entire islands. These coral reef islands are inhabited by over 700,000 people globally in nations including Kiribati, the Marshall Islands and the Maldives. Our research showed that seagrass meadows can make the right type of sand for building and maintaining the shorelines of these islands. This sand could help protect them from sea-level rise, which threatens the <a href="https://earthobservatory.nasa.gov/images/148158/preparing-for-rising-seas-in-the-maldives">existence</a> of low-lying nations.</p>
<p>Islands in the Maldives are <a href="https://theconversation.com/maldives-climate-change-could-actually-help-coral-islands-rise-again-but-theyre-still-at-risk-106586">primarily built from coral</a>, but rising sea temperatures have caused reefs to <a href="https://www.theguardian.com/environment/2016/jun/01/coral-bleaching-spreads-to-maldives-devastating-spectacular-reefs">bleach</a> in recent years, which can kill corals. Seagrass may be vital for building and maintaining these islands in the future if reefs are lost to <a href="https://theconversation.com/safe-havens-for-coral-reefs-will-be-almost-non-existent-at-1-5-c-of-global-warming-new-study-176084">climate change</a>.</p>
<h2>How seagrass builds islands</h2>
<p>If you are ever lucky enough to swim in a tropical seagrass meadow, take a close look at the leaves. You may notice that, instead of being completely smooth and green, there are what look like white grains of sand stuck to their surface.</p>
<p>A microscope reveals that these white grains are in fact tiny plants and animals. These creatures – scientists call them seagrass epibonts – are made of calcium carbonate and can include sea snails, single-celled foraminifera, crusts of coralline algae and colonies of invertebrates called bryozoans.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A seagrass meadow with microscopic organisms highlighted." src="https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=332&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=332&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=332&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=418&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=418&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507433/original/file-20230131-16-7624mi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=418&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seagrass leaves are host to a wide variety of life forms.</span>
<span class="attribution"><span class="source">Holly East</span></span>
</figcaption>
</figure>
<p>Some epibionts fall off the leaves or are whisked away when the seagrass dies to be deposited with other sediment on nearby islands. Over time, this accumulation helps to build and maintain the island shorelines. In our study, we aimed to find out how much sand was produced by organisms living in a seagrass meadow in the southern Maldives.</p>
<p>We used satellite images to map the density of seagrass and <a href="https://www.youtube.com/watch?v=Wqf-qUQWPpQ">counted the leaves</a> by randomly placing grids on the seafloor. We repeated this process 300 times, counting 27,528 individual seagrass leaves – not how most visitors to the Maldives spend their trip.</p>
<p>We collected 400 leaves and analysed them in a laboratory to work out the mass of epibionts living on them. The sand samples we collected from the meadow indicated how many of these organisms were the right size for building an island (between 0.063 and 2mm).</p>
<h2>How much sand does a seagrass meadow make?</h2>
<p>The rate at which different parts of the meadow produced sand-sized grains ranged from 0.22 to 0.86kg per square metre per year. Across the 1.1 square kilometres of seagrass meadow we studied, total annual sediment production was 762,000kg, with 482,000kg of this being the right size for island-building.</p>
<p>The volume of sand-sized sediment produced across the meadow would be large enough to build the neighbouring island of Faathihutta in just 18 years. Not all of this sand will go on to build islands – some will remain in the ocean. Nonetheless, this is a huge volume of sand being produced near islands in desperate need of sediment to bolster shorelines threatened by rising seas.</p>
<figure class="align-center ">
<img alt="A tropical coral reef island of white sand." src="https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507435/original/file-20230131-16182-kpf32l.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The coral reef island of Faathihutta, which neighbours the study site. Coral reef island nations are among the lowest-lying territories on Earth.</span>
<span class="attribution"><span class="source">Holly East</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Reef island nations will need to protect seagrass meadows and aid their recovery in areas where they have been damaged. Another challenge will be ensuring that the movement of sand from seagrass meadows to islands is not obstructed by sea walls, harbours or jetties.</p>
<p>The societal benefits of seagrass meadows remain underappreciated. In the Maldives, seagrass is often removed from tourist resorts to meet visitor expectations of pristine white sands. This is a misconception of what the shallow waters around tropical islands are supposed to look like – and one that deprives visitors of the wide variety of marine life that call seagrass meadows home, such as schools of baby fish, seahorses and turtles.</p>
<p>Tourists should now also be aware that the very survival of the coral reef islands may depend on the sand that these seagrass meadows produce.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Holly East receives funding from the British Society for Geomorphology.</span></em></p><p class="fine-print"><em><span>Jamie Johnson 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>One meadow made enough sand to create a new island in 18 years.Holly East, Lecturer in Physical Geography, Northumbria University, NewcastleJamie Johnson, Research Assistant, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1906632022-09-19T05:18:50Z2022-09-19T05:18:50ZDugongs and turtles are starving to death in Queensland seas – and La Niña’s floods are to blame<p>To rescue a turtle, University of the Sunshine Coast PhD candidate Caitlin Smith half-swam, half-crawled across mud on an inner tube. She tied a harness around its chest and front flippers, so the rest of the team could carefully pull it to safety. It was just one of 15 sick green turtles our team discovered in recent weeks in the Great Sandy Strait near Queensland’s Hervey Bay. </p>
<p>It’s not just turtles struggling at the moment. A dead dugong was found nearby, while another emaciated dugong was found still alive up the Noosa River. </p>
<p>They’re starving. Huge rains and floods have washed large quantities of sediment out to sea, where it smothers the seagrass these marine creatures rely on. There’s no relief in sight, as we enter our <a href="https://theconversation.com/la-nina-3-years-in-a-row-a-climate-scientist-on-what-flood-weary-australians-can-expect-this-summer-190542">third wet year</a> of La Niña. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485188/original/file-20220919-62013-xnmf00.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">This is the rescued green sea turtle, showing signs of poor health linked to the flooding. It was taken to a wildlife hospital.</span>
<span class="attribution"><span class="source">Caitlin Smith/Author supplied</span></span>
</figcaption>
</figure>
<h2>Why is this happening?</h2>
<p>Most of the sick sea turtles we found – as well as those found by Queensland’s Department of Environment and Science team – showed signs of starvation and illness, including the newly identified <a href="https://www.usc.edu.au/about/unisc-news/news-archive/2022/may/floods-new-mystery-disease-impact-starving-marine-turtles">soft shell disease</a>. </p>
<p>What lies behind these deaths are the rains and floods brought by <a href="https://theconversation.com/la-nina-3-years-in-a-row-a-climate-scientist-on-what-flood-weary-australians-can-expect-this-summer-190542">La Nina</a>. </p>
<p>Like much of New South Wales and Queensland, the Great Sandy Strait has been heavily hit by flooding this year, with three major floods engorging the Mary River. Floodwaters have carried huge amounts of sediment into Hervey Bay, reducing the water quality and flushing pollutants into sea turtle and dugong habitat. </p>
<p>In normal years, sediment from rivers brings a flush of nutrients, which can actually cause a seagrass boom once the water quality improves. The problem is, there’s been just too much sediment. With one La Niña after another, it’s been harder for seagrass to recover or regrow. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/restoring-seagrasses-can-bring-coastal-bays-back-to-life-147798">Restoring seagrasses can bring coastal bays back to life</a>
</strong>
</em>
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<p>As sediment from the floods spread out over the shallow seas, it made the water murkier. Soon, sunlight couldn’t penetrate the gloom to reach the seagrass meadows. Worse, <a href="https://link.springer.com/article/10.1007/s10652-013-9295-2">floods release</a> a cocktail of chemicals, including pesticides and herbicides, unintentionally washed down from farms and inundated townships. </p>
<p>The result has been widespread devastation in the Great Sandy Straits region. In May this year, a James Cook University team surveyed 2,300 square kilometres across the region and found <a href="https://www.theguardian.com/environment/2022/may/21/dugongs-and-sea-turtles-at-risk-after-queensland-floods-wipe-out-seagrass-study-shows">almost no seagrass</a> left in waters ranging from 1 metre to 17 metres. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&rect=60%2C96%2C3965%2C2921&q=45&auto=format&w=1000&fit=clip"><img alt="dead dugong" src="https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&rect=60%2C96%2C3965%2C2921&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485225/original/file-20220919-63122-5sdvl5.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">This dead dugong was found in Hervey Bay - a likely casualty of the floods.</span>
<span class="attribution"><span class="source">Ali Hammond</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Green sea turtles and dugongs are the grazers of the Australian seas and rely heavily on seagrass. In good years, they drift over these lush meadows of seagrass – which resemble grassy fields on land – eating as they go. </p>
<p>Summers are when our seagrass meadows usually flourish, letting turtles and dugong fatten up for the winter. During winter, seagrass naturally dies back. This year, local sea turtles and dugongs went into winter in poor condition, having missed out on fattening up during the summer season. </p>
<p>That’s why we’re seeing so many sick or dying animals. From January 1 to August 31 this year, volunteers from Turtles in Trouble Rescue have taken 91 sea turtles from the region to the nearest wildlife hospital, 300 kilometres away. By contrast, in 2019, before the La Niña cycle began, the group had only 12 transports. </p>
<h2>Is there nowhere else they can get food from?</h2>
<p>In flood-affected areas, turtles and dugongs have only two choices: move away, or try eating something else. </p>
<p>During the large 2010 floods, dugongs from Hervey Bay were found more than 200 kilometres south in Moreton Bay, offshore from Brisbane. Unfortunately, their migration didn’t leave them much better off – the seagrass in Moreton Bay had been hit by Brisbane River sediment. But we do know some survived. </p>
<p>Others were found dead, washed up 900 kilometres south after trying to find food and failing. Turtles can migrate too, but they’re often so weak from starvation that disease and parasites that they die before finding an alternative food source. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485201/original/file-20220919-60301-web8d0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&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">Mangrove leaves are acting as alternative food sources for desperate sea turtles.</span>
<span class="attribution"><span class="source">Photo by Kathy Townsend</span></span>
</figcaption>
</figure>
<p>What about finding something else to eat? When our team analysed the stomachs of dead sea turtles from the Hervey Bay region, we found many were full of mangrove leaves. </p>
<p>Unfortunately, these trees have a range of natural toxins designed to stop animals eating them, such as the toxic sap of the milky mangrove. Worse, as the “kidneys of the coast”, mangroves use their leaves to store concentrated salt and toxins such as <a href="https://www.frontiersin.org/articles/10.3389/fmars.2018.00484/full">heavy metals</a>. In short, this diet is no substitute. </p>
<h2>Is this part of a natural cycle of boom and bust?</h2>
<p>While turtles and dugongs do have natural variation in their populations over time – and often due to food availability – there are limits. Turtles and dugongs cannot respond to climate-induced pressures the same way fast-breeding mice can. </p>
<p>Female green sea turtles have to be 30 to 40 years old before they can <a href="https://environment.des.qld.gov.au/wildlife/animals/discovering-wildlife/turtle-watching/turtle-species/green-turtle">begin to reproduce</a>. They only undertake their long migrations to breed every three to eight years. They lay over 1,000 eggs <a href="https://www.barrierreef.org/the-reef/animals/green-turtle">in the hope</a> just one hatchling will survive the perilous seas long enough to hit reproductive age. </p>
<p>Dugongs, meanwhile, only raise a <a href="https://www.publish.csiro.au/zo/zo9840767">single calf</a> every three to seven years. These reproductive strategies make it very difficult to respond to fast changes to their environments. </p>
<p>Successive lean years caused by back-to-back La Niña events will hit both the survival rate and reproductive ability of these animals.</p>
<p>Sea turtles in poor condition will not be able to migrate successfully, which means they’re heading for a poor nesting season. Dugongs, too, will struggle. Without stores of fat, the females won’t be able to support their calves through to weaning stage. That will make it harder to replenish the population and recover from losses from starvation or relocation. We won’t know the full impact of this event until years from now. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485237/original/file-20220919-15948-magzxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">More volunteers have put up their hand to help the stranded sea turtles.</span>
<span class="attribution"><span class="source">Kathy Townsend</span></span>
</figcaption>
</figure>
<p>In response to the crisis, local volunteers have stepped up. The Turtles in Trouble Rescue group has gone from five to 50 trained members, and are working with the University of the Sunshine Coast to create a sea turtle rehabilitation centre in the area. We’ll be better prepared for the next flooding event. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dugongs-looking-to-the-gentle-sea-creatures-past-may-guard-its-future-122902">Dugongs: looking to the gentle sea creature's past may guard its future</a>
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</em>
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<img src="https://counter.theconversation.com/content/190663/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kathy Ann Townsend receives funding from Australian Research Council. </span></em></p>Floodwater carries dense clouds of sediment, choking the lush seagrass meadows on which these gentle grazers rely.Kathy Ann Townsend, Senior Lecturer in Animal Ecology, University of the Sunshine CoastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1840562022-05-31T23:14:11Z2022-05-31T23:14:11ZMeet the world’s largest plant: a single seagrass clone stretching 180 km in Western Australia’s Shark Bay<figure><img src="https://images.theconversation.com/files/466144/original/file-20220531-24-oph25e.jpeg?ixlib=rb-1.1.0&rect=6%2C34%2C4594%2C3028&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Rachel Austin</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Next time you go diving or snorkelling, have a close look at those wondrously long, bright green ribbons, waving with the ebb and flow of water. They are seagrasses – marine plants which produce flowers, fruit, and seedlings annually, like their land-based relatives. </p>
<p>These underwater seagrass meadows grow in two ways: by sexual reproduction, which helps them generate new gene combinations and genetic diversity, and also by extending their rhizomes, the underground stems from which roots and shoots emerge. </p>
<p>To find out how many different individual plants are growing in a seagrass meadow, you have to test their DNA. We did this for meadows of ribbon weed seagrass called <em>Posidonia australis</em> in the shallow sun-drenched waters of the Shark Bay World Heritage Area, in Western Australia.</p>
<p>The result blew us away: <a href="https://doi.org/10.1098/rspb.2022.0538">it was all one plant</a>. One single plant has expanded over a stretch of 180 km making it the largest known plant on Earth.</p>
<p>We collected shoot samples from ten seagrass meadows from across Shark Bay, in waters where the salt levels range from normal ocean salinity to almost twice as salty. In all samples, we studied 18,000 genetic markers to show that 200 km² of ribbon weed meadows expanded from a single, colonising seedling.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Underwater photo showing scuba diver and some equipment with seagrass." src="https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=818&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=818&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=818&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1029&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1029&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466148/original/file-20220531-24-puluwo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1029&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sampling Posidonia.</span>
<span class="attribution"><span class="source">Rachel Austin</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>How did it evolve?</h2>
<p>What makes this seagrass plant unique from others, other than its enormous size, is that it has twice as many chromosomes as its relatives. This makes it what scientists call a “polyploid”.</p>
<p>Most of the time, a seagrass seedling will inherit half the genome of each of its parents. Polyploids, however, carry the entire genome of each of their parents. </p>
<p>There are many polyploid plant species, such as potatoes, canola, and bananas. In nature they often reside in places with extreme environmental conditions. </p>
<p>Polyploids are often sterile, but can continue to grow indefinitely if left undisturbed. This seagrass has done just that.</p>
<h2>How old is this plant?</h2>
<p>The sandy dunes of Shark Bay flooded some 8,500 years ago, when the sea level rose after the last ice age. Over the following millennia, the expanding seagrass meadows made shallow coastal banks and sills through creating and capturing sediment, which made the water saltier. </p>
<p>There is also a lot of light in the waters of Shark Bay, as well as low levels of nutrients and large temperature fluctuations. Despite this hostile environment, the plant has been able to thrive and adapt.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial photograph showing coastline and shallow waters filled with dark seagrass meadows." src="https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466153/original/file-20220531-14-puluwo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The shallow, salty waters of Shark Bay.</span>
<span class="attribution"><span class="source">Angela Rossen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>It is challenging to determine the exact age of a seagrass meadow, but we estimate the Shark Bay plant is around 4,500 years old, based on its size and growth rate. </p>
<p>Other huge plants have been reported in both marine and land systems, such as a <a href="https://en.wikipedia.org/wiki/Pando_(tree)">6,000-tonne quaking aspen in Utah</a>, but this seagrass appears to be the largest to date. </p>
<p>Other huge seagrass plants have also been found, including a closely related Mediterranean seagrass called <em>Posidonia oceanica</em>, which covers more than 15 km and may be around 100,000 years old.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/100-000-year-old-seagrass-could-be-the-worlds-oldest-organism-5212">100,000-year-old seagrass could be the world's oldest organism</a>
</strong>
</em>
</p>
<hr>
<h2>Why does this matter?</h2>
<p>In the summer of 2010–11, a <a href="https://theconversation.com/climate-change-threatens-western-australias-iconic-shark-bay-32428">severe heatwave</a> hit land and sea ecosystems along the Western Australian coastline.</p>
<p>Shark Bay’s seagrass meadows suffered <a href="https://doi.org/10.3389/fmars.2019.00455">widespread damage</a> in the heatwave. Yet the ribbon weed meadows have started to recover.</p>
<p>This is somewhat surprising, as this seagrass does not appear to reproduce sexually – which would normally be the best way to adapt to changing conditions.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-threatens-western-australias-iconic-shark-bay-32428">Climate change threatens Western Australia's iconic Shark Bay</a>
</strong>
</em>
</p>
<hr>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=860&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=860&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=860&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1081&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1081&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466176/original/file-20220531-16-3vveuv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1081&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Flowers emerging from Posidonia australis seagrass.</span>
<span class="attribution"><span class="source">Angela Rossen</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We have observed seagrass flowers in the Shark Bay meadows, which indicates the seagrass are sexually active, but their fruits (the outcome of successful seagrass sex) <a href="http://doi.org/10.1093/aobpla/plaa038">are rarely seen</a>.</p>
<p>Our single plant may in fact be sterile. This makes its success in the variable waters of Shark Bay quite a conundrum: plants that don’t have sex tend to also have low levels of genetic diversity, which should reduce their ability to deal with changing environments. </p>
<p>However, we suspect that our seagrass in Shark Bay has genes that are extremely well-suited to its local, but variable environment, and perhaps that is why it does not need to have sex to be successful.</p>
<p>Even without successful flowering and seed production, the giant plant appears to be very resilient. It experiences a wide range of water temperatures (from 17°C to 30°C in some years) and salt levels. </p>
<p>Despite these variable conditions and the high light levels (which are typically stressful for seagrass), the plant can maintain its physiological processes and thrive. So how does it cope?</p>
<p>We hypothesize that this plant has a small number of somatic mutations (minor genetic changes that are not passed on to offspring) across its 180 km range that help it persist under local conditions. </p>
<p>However, this is just a hunch and we are tackling this hypothesis experimentally. We have set up a series of experiments in Shark Bay to really understand how the plant survives and thrives under such variable conditions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Underwater photo shows labelled seagrass plants on the seabed." src="https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466151/original/file-20220531-12-iqy0fg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Transplant experiments.</span>
<span class="attribution"><span class="source">Martin Breed</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The future of seagrass</h2>
<p>Seagrasses protect our coasts from storm damage, store large amounts of carbon, and provide habitat for a great diversity of wildlife. Conserving and also restoring seagrass meadows has a vital role in climate change mitigation and adaptation. </p>
<p>Seagrasses are not immune from climate change impacts: warming temperatures, ocean acidification and extreme weather events are a significant challenge for them. </p>
<p>However, the detailed picture we now have of the great resilience of the giant seagrass of Shark Bay provides us hope they will be around for many years to come, especially if serious action is taken on climate change.</p><img src="https://counter.theconversation.com/content/184056/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Sinclair receives funding from the Australian Government's National Environmental Science Program (NESP) Marine Biodiversity Hub and Australian Research Council.</span></em></p><p class="fine-print"><em><span>Gary Kendrick receives funding from the ARC, through ARC Discovery Grants, and the Australian National Environmental Science Program (NESP) Marine Biodiversity Hub</span></em></p><p class="fine-print"><em><span>Martin Breed receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jane Edgeloe 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 single seagrass plant in Shark Bay is around 4,500 years old, covers 200 square kilometres of seabed, and thrives in harsh conditions.Elizabeth Sinclair, Senior Research Fellow, The University of Western AustraliaGary Kendrick, Winthrop Professor, Oceans Institute, The University of Western AustraliaJane Edgeloe, PhD candidate (Marine Biology), The University of Western AustraliaMartin Breed, Senior Lecturer in Biology, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1564592021-03-04T15:16:24Z2021-03-04T15:16:24ZSeagrass meadows shrank by 92% in UK waters - restoring them could absorb carbon emissions and boost fish<figure><img src="https://images.theconversation.com/files/387609/original/file-20210303-19-1hcyzfs.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2102%2C1182&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A healthy seagrass meadow outside of Porthdinllaen harbour, North Wales.</span> <span class="attribution"><span class="source">Richard Unsworth</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The native oyster beds are gone. The vast saltmarshes that soaked up carbon and buffered the coast from stormy seas have been reclaimed for farms and towns. The <a href="https://theconversation.com/one-of-earths-most-biodiverse-habitats-lies-off-the-scottish-west-coast-but-climate-change-could-wipe-it-out-144832">species-rich maerl</a> and horse mussel beds have vanished and now, in <a href="https://www.frontiersin.org/articles/10.3389/fpls.2021.629962/full">new research</a>, we’ve uncovered the decline of another jewel in the UK’s marine environment: seagrass meadows.</p>
<p>Seagrass is a flowering plant that forms rippling underwater meadows in shallow coastal seas. Our study is the first to analyse all published data on this habitat in the UK, gathered from newspapers, diaries and other sources throughout history. We found that at least 44% of the UK’s seagrass has been lost since 1936 – most of it since the 1980s. But when we modelled which coastal areas were likely to have been suitable for seagrass, we found that as much as 92% of it might have disappeared.</p>
<p>Thankfully, there are still 8,493 hectares (20,987 acres) of mapped seagrass in UK waters. That’s about the same size as Newcastle upon Tyne. But seagrass may have once covered 82,000 hectares of seabed – an area as large as 115,000 football fields. While we may never know exactly how much of the UK’s seabed was once covered by this habitat – old data sets are often light on detail and contain inaccuracies – we know these underwater meadows were vast. We can only imagine how their loss has transformed the country’s coastal seas.</p>
<h2>Widespread loss</h2>
<p>Seagrass meadows are one of the world’s most efficient sinks of <a href="https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0204431">carbon</a> and support <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.12566">20%</a> of the world’s biggest fisheries. We estimated that the UK’s meadows once stored 11.5 million tonnes of carbon, equivalent to the annual emissions of 7.7 million cars. With the destruction of the seagrass, much of that carbon has been added to the atmosphere and needs to be returned. These huge meadows could also have sheltered <a href="https://www.sciencedirect.com/science/article/abs/pii/S0025326X13004633?via%3Dihub">400 million fish</a>, and annually <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969720342108?via%3Dihub">filtered pollution</a> equivalent to the amount of urine produced by the entire population of Liverpool each year.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/q92E-qeXGNI?wmode=transparent&start=6" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The first estimates of seagrass around the UK emerged in the 1930s. Descriptions and anecdotes suggest it was a common sight at the coast. Seagrass abounded in sheltered and protected spots, and there were plentiful populations in the lochs of Ireland and the west of Scotland. </p>
<p>Seagrass was considered so abundant in the 1860s that entrepreneurs writing in the Times of London described it as a potential cash crop that could rival imported cotton. While accurate data on the past size and extent of seagrass meadows is rare, the information we do have paints a picture of widespread loss. And these declines continue. The seagrass that has persisted is in a <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.150596">poor state</a> – beset by pollution, coastal development, and disturbance from boating.</p>
<p>Seagrass losses were widespread from urban coastlines to remote estuaries. While huge areas of the Humber, the Essex and Suffolk estuaries lost seagrass, so did more rural locations on the east coast of Anglesey in Wales, the Cromarty Firth in Scotland, and the inlets and estuaries of Cornwall. Areas once covered by seagrass are now lifeless seabeds in many cases.</p>
<p>These losses have numerous and complex causes, but most involve <a href="https://theconversation.com/sewage-and-livestock-waste-is-killing-britains-seagrass-meadows-new-study-91805">poor water quality</a> resulting from sewage discharges and nutrients running off farmland. Coastal developments – and mines in the past – have also polluted and disturbed seagrass.</p>
<figure class="align-center ">
<img alt="A long, thin fish stirs in a thick clump of seagrass." src="https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387703/original/file-20210304-17-1cx5tyo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Seagrass meadows support UK species such as the greater pipefish (<em>Syngnathus acus</em>).</span>
<span class="attribution"><span class="source">Naturepl.com/Alex Mustard/WWF</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A chance for renewal</h2>
<p>Our findings should not inspire blame, though. They should highlight the massive opportunities in restoring these habitats. Reviving the UK’s seagrass meadows could help fight the climate emergency, rebuild wildlife populations and put beleaguered fisheries back on a path to productivity.</p>
<p>The tide is turning for some marine habitats in the UK. Work led by the WWF is <a href="https://www.projectseagrass.org/seagrass-ocean-rescue/">replanting seagrass in West Wales</a>, oysters are being laid in <a href="https://nativeoysternetwork.org/portfolio/deep/">the Durnoch Firth</a> and coastlines are being reshaped to encourage saltmarshes in Somerset. But these projects must aspire to a bigger vision of coastal biodiversity, mirroring achievements in the US. In Virginia, thousands of hectares of seagrass <a href="https://advances.sciencemag.org/content/6/41/eabc6434">have been planted</a>. This is the scale of ambition the UK needs. </p>
<p>The evidence of its decline is stark, but seagrass was once common throughout UK waters and could be again. The opportunity for the restoration of this vital habitat is immense.</p><img src="https://counter.theconversation.com/content/156459/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard K.F. Unsworth is a founding director of the conservation charity Project Seagrass.</span></em></p><p class="fine-print"><em><span>Alix Green received funding from the Natural Environmental Research Council.</span></em></p><p class="fine-print"><em><span>Michael A. Chadwick and Peter JS Jones do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Seagrass meadows are a powerful ally in the effort to slow climate change and reverse wildlife losses.Richard K.F. Unsworth, Senior Lecturer in Marine Biology, Swansea UniversityAlix Green, PhD Candidate in Conservation Biology, UCLMichael A. Chadwick, Senior Lecturer in Aquatic Biology, King's College LondonPeter JS Jones, Reader in Environmental Governance, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1501762020-11-19T03:14:02Z2020-11-19T03:14:02ZChina’s Belt and Road mega-plan may devastate the world’s oceans, or help save them<figure><img src="https://images.theconversation.com/files/370236/original/file-20201119-20-mge5ja.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5464%2C3623&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock </span></span></figcaption></figure><p>China’s signature foreign policy, the Belt and Road initiative, has garnered much attention and controversy. Many have voiced fears about how the huge infrastructure project might expand China’s military and political influence across the world. But the environmental damage potentially wrought by the project has received scant attention.</p>
<p>The policy aims to connect China with Europe, East Africa and the rest of Asia, via a massive network of <a href="https://merics.org/en/analysis/mapping-belt-and-road-initiative-where-we-stand">land and maritime routes</a>. It includes building a series of deepwater ports, dubbed a “<a href="https://www.researchgate.net/publication/307522284_Silk_Roads_and_Strings_of_Pearls_The_Strategic_Geography_of_China%27s_New_Pathways_in_the_Indian_Ocean">string of pearls</a>”, to create <a href="https://www.aph.gov.au/about_parliament/parliamentary_departments/parliamentary_library/pubs/briefingbook45p/chinasroad">secure and efficient</a> sea transport.</p>
<p>All up, the cost of investments associated with the project have been estimated at as much as <a href="https://www.independent.co.uk/environment/china-belt-and-road-initiative-silk-route-cost-environment-damage-a8354256.html">US$8 trillion</a>. But what about the environmental cost? </p>
<p>Coastal development typically damages habitats and species on land and in the sea. So the Belt and Road plan may irreversibly damage the world’s oceans – but it also offers a chance to better protect them.</p>
<figure class="align-center ">
<img alt="A map showing sea and land routes planned under the Belt and Road initiative." src="https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/370229/original/file-20201119-13-1393edh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A map showing sea and land routes planned under the Belt and Road initiative.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Controversial deals</h2>
<p>China’s President Xi Jinping announced the Belt and Road initiative in 2013. Since then, China has <a href="https://www.itf-oecd.org/sites/default/files/docs/belt-road-initiative-maritime-trade-flows_1.pdf">already</a> helped build and operate at least 42 ports in 34 countries, including in Greece, Sri Lanka and Pakistan. As of October this year, 138 countries had <a href="https://www.eastasiaforum.org/2020/10/27/building-chinas-belt-and-road-initiative-bit-by-bit/">signed onto</a> the plan. </p>
<p>The Victorian government <a href="https://www.vic.gov.au/sites/default/files/2019-02/Belt-and-Road-Initiative-MOU.pdf">joined</a> in 2018, in a move that stirred <a href="https://www.abc.net.au/news/2018-10-26/victoria-and-china-belt-and-road-signing-mou/10435148">political controversy</a>. Those tensions have heightened in recent weeks, as the federal government’s relationship with China <a href="https://www.abc.net.au/news/2020-11-18/china-australia-relations-sour--diplomat-releases-list/12897788">deteriorates</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-is-there-so-much-furore-over-chinas-belt-and-road-initiative-139461">Why is there so much furore over China's Belt and Road Initiative?</a>
</strong>
</em>
</p>
<hr>
<p>Victorian Premier Daniel Andrews recently reiterated his commitment to the deal, <a href="https://www.theage.com.au/politics/victoria/china-s-gateway-daniel-andrews-belt-and-road-pitch-to-beijing-20201002-p561b9.html">saying</a>: “I think a strong relationship and a strong partnership with China is very, very important.”</p>
<p>However, political leaders signing up to the Belt and Road plan must also consider the potential environmental consequences of the project.</p>
<figure class="align-center ">
<img alt="Dan Andrews in Beijing" src="https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/370233/original/file-20201119-15-5ks8g7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Victorian Premier Daniel Andrews is committed to the Belt and Road initiative.</span>
<span class="attribution"><span class="source">Twitter</span></span>
</figcaption>
</figure>
<h2>Bigger ports and more ships</h2>
<p>As well as ports, the Belt and Road plan involves roads, rail lines, dams, airfields, pipelines, cargo centres and telecommunications systems. <a href="https://www.sciencedirect.com/science/article/pii/S0308597X19307675">Our research</a> has focused specifically on the planned port development and expansion, and increased shipping traffic. We examined how it would affect coastal habitats (such as seagrass, mangroves, and saltmarsh), coral reefs and threatened marine species.</p>
<p>Port construction can <a href="https://www.sciencedirect.com/science/article/pii/S0025326X13003822">impact species and habitats</a> in several ways. For example, developing a site often requires clearing mangroves and other coastal habitats. This can harm animals and release carbon stored by these productive ecosystems, accelerating climate change. Clearing coastal vegetation can also increase run-off of pollution from land into coastal waters. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ships-moved-more-than-11-billion-tonnes-of-our-stuff-around-the-globe-last-year-and-its-killing-the-climate-this-week-is-a-chance-to-change-150078">Ships moved more than 11 billion tonnes of our stuff around the globe last year, and it’s killing the climate. This week is a chance to change</a>
</strong>
</em>
</p>
<hr>
<p>Ongoing <a href="https://www.sciencedirect.com/science/article/pii/S0025326X06003778">dredging</a> to maintain shipping channels stirs up sediment from the seafloor. This sediment smothers sensitive habitats such as seagrass and coral and damages wildlife, including fishery species on which many coastal communities depend. </p>
<p>A rise in shipping traffic associated with trade expansion increases the risk to animals being <a href="https://theconversation.com/thames-humpback-whale-killed-by-ship-the-casualty-of-a-global-problem-125284">directly struck by vessels</a>. More ships also means a greater risk of shipping accidents, such as the <a href="https://theconversation.com/mauritius-must-protect-vulnerable-coastal-communities-from-the-effects-of-the-oil-spill-145411">oil spill</a> in Mauritius in July this year. </p>
<figure class="align-center ">
<img alt="Seagrass in the Pacific Ocean" src="https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369759/original/file-20201117-13-1dj6ap8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dredging can cause sediment to smother seagrass.</span>
<span class="attribution"><span class="source">iStock</span></span>
</figcaption>
</figure>
<h2>Ocean habitat destroyed</h2>
<p>Our spatial analysis found construction of new ports, and expansion of existing ports, could lead to a loss of coastal marine habitat equivalent in size to 69,500 football fields.</p>
<p>These impacts were proportionally highest in small countries with relatively small coastal areas - places such as Singapore, Togo, Djibouti and Malta - where a considerable share of coastal marine habitat could be degraded or destroyed. </p>
<p>Habitat loss is particularly concerning for small nations where local livelihoods depend on coastal habitats. For example, mangroves, coral reefs, and seagrass protect coasts from <a href="https://theconversation.com/as-communities-rebuild-after-hurricanes-study-shows-wetlands-can-significantly-reduce-property-damage-83935">storm surges</a> and sea-level rise, and provide <a href="https://theconversation.com/loss-of-marine-habitats-is-threatening-the-global-fishing-industry-new-research-96561">nursery habitat for fish and other marine species</a>.</p>
<p>Our analysis also found more than 400 threatened species, including mammals, could be affected by port infrastructure. More than 200 of these are at risk from an increase in shipping traffic and noise pollution from ships. This sound can travel many kilometres and affect the mating, nursing and feeding of species such as dolphins, manatees and whales. </p>
<figure class="align-center ">
<img alt="A manatee" src="https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/370234/original/file-20201119-14-147h7x8.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">Noise pollution from ships can affect threatened species such as manatees.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>But there are opportunities, too</h2>
<p>Despite these environmental concerns, the Belt and Road initiative also offers an <a href="https://www.cell.com/one-earth/fulltext/S2590-3322(20)30429-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2590332220304292%3Fshowall%3Dtrue">opportunity</a> to improve biodiversity conservation, and progress towards environmental targets such as the United Nations’ <a href="https://sdgs.un.org/goals">Sustainable Development Goals</a>. </p>
<p>For example, China could implement a broad, consistent environmental framework that ensures individual infrastructure projects are held to the same high standards. </p>
<p>In Australia, <a href="https://www.transport.wa.gov.au/Freight-Ports/ports-legislation-and-policies.asp">legislation</a> helps prevent damage to wildlife from port activities. For example, <a href="https://doi.org/10.1016/j.ocecoaman.2017.03.028">go-slow zones</a> minimise the likelihood of vessels striking iconic wildlife such as turtles and dugongs. Similarly, protocols for the transport, handling, and export of mineral concentrates and other potentially hazardous materials minimise the risk of pollutants entering waterways.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/china-just-stunned-the-world-with-its-step-up-on-climate-action-and-the-implications-for-australia-may-be-huge-147268">China just stunned the world with its step-up on climate action – and the implications for Australia may be huge</a>
</strong>
</em>
</p>
<hr>
<p>The Belt and Road initiative should require similar environmental protections across all its partner countries, and provide funding to ensure they are enacted. </p>
<p>China has recently sought to boost its environment credentials on the world stage – such as by <a href="https://theconversation.com/china-just-stunned-the-world-with-its-step-up-on-climate-action-and-the-implications-for-australia-may-be-huge-147268">adopting a target</a> of net-zero carbon emissions by 2060. The global nature of the Belt and Road initiative means China is in a unique position: it can cause widespread damage, or become an international leader on environmental protection.</p><img src="https://counter.theconversation.com/content/150176/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mischa Turschwell receives funding from the Blue Economy Cooperative Research Centre </span></em></p><p class="fine-print"><em><span>Christopher Brown receives funding from the Australian Research Council, private philanthropy, the Blue Economy Cooperative Research Centre and the National Environmental Science Program. </span></em></p><p class="fine-print"><em><span>Ryan M. Pearson receives funding from the NSW Saving Our Species Program. </span></em></p>China’s signature foreign policy is controversial for lots of reasons. But the environmental damage potentially wrought by the project has received scant attention.Mischa Turschwell, Research Fellow, Griffith UniversityChristopher Brown, Senior Lecturer, School of Environment and Science, Griffith UniversityRyan M. Pearson, Research Fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1477982020-10-20T12:19:26Z2020-10-20T12:19:26ZRestoring seagrasses can bring coastal bays back to life<figure><img src="https://images.theconversation.com/files/364103/original/file-20201018-13-1fbnw6t.jpg?ixlib=rb-1.1.0&rect=17%2C35%2C3944%2C2934&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eelgrasses covered with small snails, which keep the leaves clean by feeding on algae that live on them.</span> <span class="attribution"><span class="source">Jonathan Lefcheck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>A century ago Virginia’s coastal lagoons were a natural paradise. Fishing boats bobbed on the waves as geese flocked overhead. Beneath the surface, miles of seagrass gently swayed in the surf, making the seabed look like a vast underwater prairie. </p>
<p>More than <a href="https://ocean.si.edu/ocean-life/plants-algae/seagrass-and-seagrass-beds">70 species</a> of seagrasses grow in shallow waters around the world, on every continent except Antarctica. In Virginia, beds of <a href="https://www.fisheries.noaa.gov/feature-story/importance-eelgrass">eelgrass</a> (<em>Zostera marina</em>) provided habitat for bay scallops and food for birds, and kept barrier islands from washing away. Eelgrass was so common that people who lived near the shore packed and baled it to <a href="https://www.jlconline.com/how-to/insulation/a-history-of-eel-grass-insulation_o">use as insulation</a> for homes, schools and hospitals. </p>
<p>In the 1930s, however, pandemic plant disease and repeated hurricanes eliminated the eelgrass along Virginia’s eastern shore. The once-vibrant seafloor became barren mud, leading to a loss of “wildfowl, the cream of salt-water fishing, most of the clams and crabs, and all of the bay scallops,” sportsman and publisher <a href="https://cpl.org/the-derrydale-press/">Eugene V. Connett</a> <a href="https://www.jamescumminsbookseller.com/pages/books/239493/eugene-v-connett/duck-shooting-along-the-atlantic-tidewater-chapters-by-frederick-c-lincoln-lynn-bogue-hunt">wrote in 1947</a>. </p>
<p>We are marine scientists who study <a href="https://scholar.google.com/citations?user=bVEVdsEAAAAJ&hl=en">seagrasses</a>, <a href="https://scholar.google.com/citations?user=wTArpJgAAAAJ&hl=en">marine biodiversity</a> and <a href="https://scholar.google.es/citations?user=l6zTkPUAAAAJ&hl=en">coastal ecosystems</a>. In a newly published study, we describe the results of a 20-year mission to reintroduce eelgrass into Virginia coastal bays using a <a href="http://dx.doi.org/%2010.1126/sciadv.abc6434">novel seed-based approach</a>. </p>
<p>This project has now restored 9,600 acres of seagrasses across four bays – one of the most successful marine restoration efforts anywhere in the world. It has triggered large increases in fishes and invertebrates, made the water clearer and trapped large quantities of carbon in seafloor sediments, helping to slow climate change. We see this work as a blueprint for restoring and maintaining healthy ecosystems along coastlines around the world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic of seagrasses and other near-shore ecosystems." src="https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364122/original/file-20201018-13-mda8ht.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=451&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seagrasses and other coastal habitats stabilize coastlines, store carbon and provide habitat for fish and shellfish.</span>
<span class="attribution"><a class="source" href="https://live.staticflickr.com/65535/49983475236_35e2e8d974_o.png">Hisham Ashkar/GRID-Arendal</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why didn’t seagrasses recover naturally?</h2>
<p>Development, nutrient runoff and other human impacts have damaged marshes, mangroves, coral reefs and seagrasses in many bays and estuaries worldwide. Loss or shrinkage of these key habitats has reduced commercial fisheries, increased erosion, made coastlines more vulnerable to floods and storms and harmed many types of aquatic life. Rapid climate change has compounded these effects through <a href="https://theconversation.com/ocean-warming-has-fisheries-on-the-move-helping-some-but-hurting-more-116248">rising global temperatures</a>, more <a href="https://theconversation.com/more-frequent-and-intense-tropical-storms-mean-less-recovery-time-for-the-worlds-coastlines-123335">frequent and severe storms</a> and <a href="https://theconversation.com/as-climate-change-alters-the-oceans-what-will-happen-to-dungeness-crabs-61501">ocean acidification</a>.</p>
<p>In the late 1990s, local residents told two of us who are longtime students of seagrasses (Robert “JJ” Orth and Karen McGlathery) that they had spotted small patches of eelgrass in shallow waters off Virginia’s eastern shore. For years the conventional view had been that seagrasses in this area had not recovered from the events of the 1930s because human activities had <a href="https://doi.org/10.1016/j.aquabot.2005.07.007">made the area inhospitable for them</a>.</p>
<p>But studies showed that water quality in these coastal bays was <a href="https://doi.org/10.1007/BF02782971">comparatively good</a>. This led us to explore a different explanation: Seeds from healthy seagrass populations elsewhere along the Atlantic coast simply weren’t reaching these isolated bays. Seagrasses are underwater flowering plants, so seeds are among the main ways they reproduce and spread to new environments.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite map showing project area in coastal Virginia." src="https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=674&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=674&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364352/original/file-20201019-17-1ed9xo2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=674&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eelgrass beds were restored in four bays at the southern tip of Virginia’s eastern shore on the Atlantic coast.</span>
<span class="attribution"><span class="source">David J. Wilcox/VIMS</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Sowing a new crop</h2>
<p>From our <a href="https://doi.org/10.2307/1941597">earlier research</a>, we knew that when eelgrass seeds fall from the parent plant, they sink to the sea bottom quickly and don’t move far from where they land. We also knew that these seeds don’t germinate until late fall or early winter. This meant that if we collected the seeds in spring, when eelgrass flowers, we could hold them until the fall, helping them survive over the months in between.</p>
<p>We decided to try reseeding eelgrass in the areas where they were missing. Starting in 1999, we collected seeds by hand from underwater meadows in nearby Chesapeake Bay – plucking the long reproductive shoots, bringing them back to our laboratory and holding them in large outdoor seawater tanks until they released their seeds naturally. After about 10 years we started gathering the grasses using a custom-built underwater “lawn mower” to collect many more of the reproductive shoots than we could by hand. </p>
<p>In 2001 we sowed our first round by simply tossing seeds from a boat. Our first test plots covered 28 acres of mud flats in waters 2 to 3 feet deep. Returning the following year, we saw new seedlings sprouting up. </p>
<p>Each year since then, the <a href="https://www.vims.edu">Virginia Institute of Marine Science</a> and the <a href="https://www.nature.org/en-us/about-us/where-we-work/united-states/virginia/">Nature Conservancy’s Virginia Coast Reserve</a>, along with staff and students from the <a href="https://www.vcrlter.virginia.edu">University of Virginia</a>, have led a team of scientists and citizens to collect and seed a combined 536 acres of bare bottom in several coastal bays.</p>
<p>These initial plots took off and rapidly expanded. By 2020 they covered 9,600 acres across four bays. Several factors helped them flourish. These bays are naturally flushed with cool, clean water from the Atlantic Ocean. And they lie off the tip of Virginia’s eastern shore, where there is little coastal development. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/K9NyfPLINtk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">To restore eelgrasses to Virginia coastal bays, scientists collected grasses in other areas, harvested their seeds and spread them by hand.</span></figcaption>
</figure>
<h2>Sheltering marine life and storing carbon</h2>
<p>Since eelgrass disappeared from these bays in the 1930s, human understanding of seagrass ecosystems has evolved. Today people don’t pack their walls full of seagrass insulation but instead value different services they provide, such as habitat for fish and shellfish – including many <a href="https://doi.org/10.1111/conl.12645">commercially and recreationally important species</a>.</p>
<p>Scientists and government agencies also have recognized the importance of coastal systems in capturing and storing so-called “<a href="https://oceanservice.noaa.gov/facts/bluecarbon.html">blue carbon</a>.” In fact, we now know that seagrasses constitute a globally significant <a href="https://doi.org/10.1038/ngeo1477">carbon sink</a>. They are a key tool for reducing carbon dioxide in the atmosphere and <a href="https://doi.org/10.1038/s41598-020-64094-1">slowing climate change</a></p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>We are working to understand the valuable services that our restored seagrass beds provide. To our surprise, fish and invertebrates returned within only a few years as the meadows expanded. These organisms have established extensive food webs that include species ranging from tiny seahorses to 6-foot-long sandbar sharks.</p>
<p>Other benefits were equally dramatic. Water in the bays become clearer as the seagrass canopy trapped floating particles and deposited them onto the bottom, burying significant stocks of carbon and nitrogen in sediments bound by the grasses’ roots. Our research is the first to verify the overall net carbon captured by seagrass, and is now being used to issue carbon offset credits that in turn <a href="https://vaseagrant.org/eelgrass-carbon-credits/">create more funds for restoration</a>. </p>
<p>One big question was whether restoring seagrasses could make it possible to bring back bay scallops, which once generated millions of dollars for the local economy. Since bay scallops no longer existed in Virginia, we obtained broodstock from North Carolina, which we have <a href="https://chesapeakebaymagazine.com/return-of-the-bay-scallop/">reared and released annually</a> since 2013. Regular surveys now reveal a growing population of bay scallops in the restored eelgrass, although there is still some way to go before they reach levels seen in the 1930s.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial photo of restored seagrass beds" src="https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/364124/original/file-20201018-19-186i0gd.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">Restored seagrass beds (dark areas) along Virginia’s Atlantic coast, with sunlight reflecting from a small island.</span>
<span class="attribution"><span class="source">Jonathan Lefcheck</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A model for coastal restoration</h2>
<p>Repairing damaged ecosystems is such an urgent mission worldwide that the United Nations has designated 2021-2030 as the <a href="https://www.decadeonrestoration.org/">U.N. Decade on Ecosystem Restoration</a>. We see the success we have achieved with eelgrass restoration as a prime model for similar efforts in coastal areas around the world. </p>
<p>Our project focused not only on reviving this essential habitat, but also on charting how restoring seagrasses affected the ecosystem and on the co-restoration of bay scallops. It provides a road map for involving scholars, nonprofits organizations, citizens and government agencies in an ecological mission where they can see the results of their work.</p>
<p>Recent assessments show that the restored zone only covers about 30% of the total habitable bottom in our project area. With continued support, eelgrass – and the many benefits it provides – may continue to thrive and expand well into the 21st century.</p><img src="https://counter.theconversation.com/content/147798/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert J. Orth receives funding from the Virginia Department of Environmental Quality, National Oceanographic and Atmospheric Administration Office of Coastal Zone Management, U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, Virginia Recreational Fishing License Fund, Maryland Department of Natural Resources, Maryland Department of the Environment, Keith Campbell Foundation for the Environment, Virginia Sea Grant . He is an elected official on the Gloucester County Board of Supervisors as an independent. </span></em></p><p class="fine-print"><em><span>Jonathan Lefcheck is supported by the Michael E. Tennenbaum Secretarial Scholar gift to the Smithsonian Institution.</span></em></p><p class="fine-print"><em><span>Karen McGlathery receives funding from the National Science Foundation, the National Fisheries and Wildlife Foundation, and Virginia Sea Grant.</span></em></p>Healthy seagrasses form underwater meadows teeming with fish and shellfish. A successful large-scale restoration project in Virginia could become a model for reseeding damaged seagrass beds worldwide.Robert J. Orth, Professor of Marine Science, Virginia Institute of Marine ScienceJonathan Lefcheck, Research Scientist, Smithsonian Environmental Research Center, Smithsonian InstitutionKaren McGlathery, Professor of Environmental Sciences and Director, Environmental Resilience Institute, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1238392019-09-24T14:29:58Z2019-09-24T14:29:58ZRevealed: how underwater plants and corals can help animals survive marine heatwaves<figure><img src="https://images.theconversation.com/files/293802/original/file-20190924-51452-1ha3xbs.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">Damsea / shutterstock</span></span></figcaption></figure><p>Most of the heat from global warming has gone <a href="https://theconversation.com/new-findings-on-ocean-warming-5-questions-answered-106215">into the oceans</a>, so it is no wonder that the seas are experiencing massive heatwaves too. What’s more, climate change is causing a fall in global <a href="https://www.carbonbrief.org/guest-post-how-global-warming-is-causing-ocean-oxygen-levels-to-fall">ocean oxygen levels</a>.</p>
<p>Hotter oceans, with less oxygen, sounds like bad news for marine life. But new research colleagues and I have published in <a href="https://advances.sciencemag.org/content/5/9/eaax1814.abstract">Science Advances</a> has shown how marine plants and organisms that live along the coasts – algae, seagrasses, mangrove and corals – can add oxygen to the water. We found this extra oxygen protects animals from heat stress and will make them more resilient to climate change.</p>
<p>Scientists have often studied the effect of temperature on the physiological response of marine animals. But, until now, the role of the oxygen produced by organism such as plants, algae and corals has been overlooked.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293804/original/file-20190924-51410-130nzy1.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bubbles of oxygen produced by seagrass photosynthesis are visible on the leaves.</span>
<span class="attribution"><span class="source">Marco Fusi</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To see if this effect would be apparent across a variety of animals you’d find in the sea, we rounded up a total of 249 animals from six species belonging to four distantly related groups. Two of the species, we found in mangroves near our fieldwork site on the Saudi coast of the Red Sea: the spiny rock crab and the small silverside fish. From a nearby coral reef we found the black sea cucumber and the colourful fish <em>Dascyllus</em>. And finally we gathered up samples of the horsemussel and <em>Ophiocoma</em>, a “brittle star” closely related to starfish.</p>
<p>We then took these sample animals back to the lab, where we could measure their tolerance to increased water temperature at normal and high levels of oxygen. In this way, we could mimic the real condition these animals experience in the environment.</p>
<p>The animals we tested are all unable to “thermoregulate” like mammals, and so their metabolisms accelerate with the temperature. The warmer it is, the more oxygen is required. </p>
<p>We found that high levels of oxygen allowed them to cope with higher temperature. This is because oxygen is the combustive agent that helps them produce more energy from their food. (Something similar is also used in human medicine: hyperbaric oxygen therapy can form part of the treatment for cancers and <a href="https://theconversation.com/multiple-sclerosis-survivors-swear-by-hyperbaric-oxygen-but-does-it-work-64405">other conditions</a>.)</p>
<p>It makes sense, therefore, for these animals to live close to organisms like seagrass or coral which can guarantee a good supply of oxygen during the warmest hours of the day, when photosynthesis is also at its peak.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/293805/original/file-20190924-51452-3dhckb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fish benefit from the oxygen produced by tiny photosynthetic algae that live on coral.</span>
<span class="attribution"><span class="source">Marco Fusi</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our research also looked at which plants were responsible for adding oxygen to the water, and when. Every five minutes for a whole year we monitored the temperature and oxygen levels of the seawater among mangrove trees, seagrasses and a coral reef – again, all near our research site in the Red Sea. We showed that the level of oxygen in the water fluctuated significantly. In fact, during the warmest hours of the day it was more than double the normal saturation. </p>
<p>Mangroves, coral reefs and seagrass meadows are all vital for marine biodiversity, for fisheries and as habitable links to help individual animals jump from one population to another. But often they are threatened by human activities, such as dredge fishing and the expansion and development of coastal cities.</p>
<p>If more oxygen can make marine species more resilient to temperature stress then oxygen – and the organisms that generate it – must be taken into account in environmental policies along the coasts. In Scotland, for example, kelp is an important source of oxygen which may help associated animals face a rapidly changing environment. It therefore deserves scientific attention and governmental protection.</p><img src="https://counter.theconversation.com/content/123839/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marco Fusi 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>Oxygen produced by these plants helps animals boost their metabolism to match the heat.Marco Fusi, Post Doctoral Fellow in Ecology, Edinburgh Napier UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1198822019-07-05T06:17:22Z2019-07-05T06:17:22ZEelgrass keeps the oceans alive and preserves shipwrecks, so just cope when it tickles your feet<figure><img src="https://images.theconversation.com/files/282800/original/file-20190705-51273-cs9ef0.png?ixlib=rb-1.1.0&rect=0%2C8%2C2079%2C1486&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sea grass meadows at Bonna Point. </span> <span class="attribution"><span class="source">Valentina Hurtado-McCormick, Author provided</span></span></figcaption></figure><p><em>Sign up to the Beating Around the Bush newsletter <a href="https://theconversation.com/au/newsletters">here</a>, and suggest a plant we should cover at batb@theconversation.edu.au.</em></p>
<hr>
<p>Have you ever walked into the ocean from a stunning Australian beach and realised the sand was covered with hundreds of ticklish leaves? This submerged canopy is a seagrass meadow, and while you might see them as a nuisance to swim past, they’re a hidden treasure. </p>
<p>Seagrasses are the only group of flowering plants that have adapted to the marine environment. This group comprises nearly 60 species, which typically occupy tropical and temperate regions of the world distributed across 1,646,788 km2.</p>
<p>There is a disproportionately large number of temperate seagrass species in southern Australia, with <em>Zostera</em> species dominating extensive and very diverse meadows. </p>
<p>Eelgrass (<em>Zostera muelleri</em>) is one of the dominant meadow-forming species in Australia. It has the widest distribution of its family (<em>Zosteraceae</em>) in temperate Australian waters, and is vital to our oceans’ health.</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=802&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=802&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=802&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1008&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1008&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282809/original/file-20190705-51258-4oiuqk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1008&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"></span>
<span class="attribution"><span class="source">The Conversation</span></span>
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<hr>
<h2>Don’t call me weedy!</h2>
<p>These aquatic plants have evolved myriad adaptations to survive in the seas, and contrary to what many people think, seagrasses are very different from seaweeds. </p>
<p>Seaweeds are comparatively simple organisms: they are macroalgae with no vascular tissue, which is what conducts water and nutrients throughout a plant. In comparison, eelgrass has leaves, root and rhizomes, with flowers, fruits and seeds for reproduction. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282782/original/file-20190705-51292-1o32apa.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"></span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jmaughn/11866178586/in/photolist-j5zgtY-GBqXjh-iLbnAG-5tcCuv-5VVnwM-Hmy77-i2XzEB-cQqsgq-9Ut18t-J72Lf-5tcsXn-aeefio-H3w7c-4GW736-eh9ykD-8Qvgjq-LCSGZj-9F3CCR-3d3GuP-26LmfNQ-5tcCgt-23o58PT-iL8ESt-5DdFbz-Td3SXi-9F6xH5-8im7bV-ZMNmbf-5th1zy-4w4enc-6bWMiP-eoL5vP-8ipkYo-c1jVyh-6bWyAa-6bWPkK-7zxJqG-5N6wSE-66uTXP-bBn8Wy-5nEjrU-cXNSh7-aca1ie-H3vWX-H3u4Y-H3w4P-6bWQ6a-6c1Ytq-c1jVvY-8Fzqtf">J. Maughn/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>They do, however, share one thing. Seagrasses and seaweeds are “holobionts” – meaning that they each play host to a range of microorganisms such as bacteria, fungi and microalgae that help to support their health and survival.</p>
<p>Research has shown that these <a href="https://www.ncbi.nlm.nih.gov/m/pubmed/29977008/">crucial host-microbe relationships</a> can be <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2019.01011/full">easily disrupted</a>. </p>
<p>Climate change is not just affecting the seagrass host; the entire holobiont and even the environment it occupies are suffering from <a href="https://www.frontiersin.org/articles/10.3389/fmars.2018.00190/full">rising temperatures</a>. </p>
<h2>Purple plants in warm waters</h2>
<p>My research involves studying the response of seagrass and their associated microbes to environmental degradation. I realised how much warming oceans were affecting eelgrass when I suddenly came across <em>purple</em> shoots in a meadow I was sampling once a month. </p>
<p>I was shocked. I had never seen anything like it. </p>
<p>While previous research has described the phenomenon of <a href="https://www.researchgate.net/publication/272536989_Leaf_reddening_in_seagrasses">seagrass leaf reddening</a>, I’d never heard of seagrass going purple in this specific black-purple-white pattern. </p>
<p>We already knew that the eelgrass accumulates red pigments as a sunscreen against the increased <a href="https://pubs.rsc.org/en/content/articlehtml/2015/pp/c4pp90032d">UV radiation</a> that results from ozone depletion and related consequences of climate change. My PhD (soon to be published) has found that this colour change has a strong effect on the microbial communities that live on seagrass leaves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282793/original/file-20190705-51288-1be14ky.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">Seagrasses establish and maintain fundamental relationships with the microbes that live among them.</span>
<span class="attribution"><span class="source">Valentina Hurtado McCormick</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Why should we care?</h2>
<p>Besides producing weird sensations on human feet, eelgrass and its counterparts are a crucial part of our coastal ecosystems. Probably the best example is their nursery role in supporting juvenile fish and crustaceans.</p>
<p>They also provide food for a wide range of grazers, from dugongs to the green sea turtle (as featured in the movie Finding Nemo), which feed on bounteous seagrass meadows. </p>
<p>Finally, we can also thank them for sequestering <a href="https://theconversation.com/we-desperately-need-to-store-more-carbon-seagrass-could-be-the-answer-105524">huge amounts of organic carbon</a> that would otherwise contribute enormously to the greenhouse effect. Referred to as “blue carbon sinks”, researchers have calculated seagrass meadows could store <a href="https://books.google.com.au/books?id=t8aPBQAAQBAJ&pg=PA132&lpg=PA132&dq=19.9+Pg+of+organic+carbon&source=bl&ots=y4OULZ9BAK&sig=ACfU3U00_YW9lj0FFV6hVb_VsyPt971WCQ&hl=en&sa=X&ved=2ahUKEwjVkKmoy5zjAhUVmuYKHQPnAAoQ6AEwCnoECAkQAQ#v=onepage&q=19.9%20Pg%20of%20organic%20carbon&f=false">19.9 gigatonnes of organic carbon worldwide</a>.</p>
<p>I could keep writing about the virtues of <em>Zostera</em> species (and seagrasses in general) for much, much longer, but I will leave you with a single thought: we breathe and eat from a healthy ocean, and the ocean is not healthy without seagrass.</p>
<h2>Not just grass under your feet</h2>
<p>Seagrass is so protective, I think of them as one of the most altruistic plants on the planet. They keep <a href="https://www.nature.com/news/ocean-meadows-scrub-seawater-of-harmful-bacteria-1.21504">waterborne pathogens in check and neutralise harmful bacteria</a>, keeping coral reefs healthy, and acting as an important part of the ocean’s well-being.</p>
<p>On the other hand, these aquatic plants also help preserve human heritage. They create a thick sediment layer on the seafloor, beneath which <a href="https://theconversation.com/seagrass-protector-of-shipwrecks-and-buried-treasure-103364">shipwrecks and other treasures</a> are buried and protected from decomposition.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/seagrass-protector-of-shipwrecks-and-buried-treasure-103364">Seagrass, protector of shipwrecks and buried treasure</a>
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</em>
</p>
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<p>For some <a href="https://link.springer.com/content/pdf/10.1007%2F978-3-319-71354-0.pdf">400 million years</a>, eelgrass and other seagrass species have protected the ocean, our planet, and the creatures who live here.</p>
<p>In return, we have managed to create uncountable ways to directly or indirectly threaten seagrass-based ecosystems. As a result, meadows have declined globally at the accelerated rate of <a href="https://www.pnas.org/content/pnas/106/30/12377.full.pdf">7% per year</a>.</p>
<p>For many of us, seagrass meadows are simply an obstacle to get past on the way to the waves. But for those of us who spend our days with a snorkel and collection tubes, these little watery plants mean far more. When I look at a single seagrass leaf, I see an entire microcosm of interacting entities.</p>
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<img alt="" src="https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=199&fit=crop&dpr=1 600w, https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=199&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=199&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=251&fit=crop&dpr=1 754w, https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=251&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/238283/original/file-20180927-48650-1veiqyi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=251&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><a href="https://www.facebook.com/groups/BeatingAroundTheBush">Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.</a></em></p><img src="https://counter.theconversation.com/content/119882/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Valentina Hurtado-McCormick receives funding from the Faculty of Science, the Graduate Research School (GRS), and the Climate Change Cluster (C3), University of Technology Sydney (UTS). This PhD research was also funded through the Australian
Research Council (ARC) Discovery Program scheme (Future Fellowship Grant FT130100218 to Justin Seymour) and the William Macleay Microbiological Scientific Research Fund, Linnean Society of New South Wales (William Macleay Award for Microbiology Research to Valentina Hurtado-McCormick).</span></em></p>Seagrass may look unassuming, but healthy oceans depend on the huge meadows that grow in temperate and tropical waters.Valentina Hurtado-McCormick, PhD Candidate, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1161772019-05-21T19:41:25Z2019-05-21T19:41:25ZFrom sharks in seagrass to manatees in mangroves, we’ve found large marine species in some surprising places<p>When we think of mangrove forests, seagrass meadows and saltmarshes, we don’t immediately think of shark habitats. But the first <a href="https://doi.org/10.1016/j.tree.2019.04.004">global review</a> of links between large marine animals (megafauna) and coastal wetlands is challenging this view – and how we might respond to the biodiversity crisis.</p>
<p>Mangrove forests, seagrass meadows and saltmarshes support rich biodiversity, underpin the <a href="https://theconversation.com/loss-of-marine-habitats-is-threatening-the-global-fishing-industry-new-research-96561">livelihoods</a> of more than a billion people worldwide, <a href="https://theconversation.com/rising-seas-allow-coastal-wetlands-to-store-more-carbon-113020">store carbon</a>, and protect us from extreme weather events.</p>
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<img alt="" src="https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=251&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=251&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275559/original/file-20190521-23823-1ket9ng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=251&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">Mangrove forests, seagrass meadows and saltmarshes are the three key vegetated habitats found in coastal wetlands.</span>
<span class="attribution"><span class="source">Tom Rayner/www.shutterstock.com</span></span>
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<p>We know marine megafauna also use these habitats to live, feed and breed. Green turtles and manatees, for instance, are known to eat seagrass, and dolphins hunt in mangroves. </p>
<p>But new associations are also being discovered. The bonnethead shark – a close relative of hammerheads – was <a href="https://theconversation.com/omnivore-sharks-and-cannibal-hippos-the-strange-truth-about-dinnertime-in-the-animal-kingdom-103492">recently found</a> to eat and digest seagrass.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/omnivore-sharks-and-cannibal-hippos-the-strange-truth-about-dinnertime-in-the-animal-kingdom-103492">Omnivore sharks and cannibal hippos – the strange truth about dinnertime in the animal kingdom</a>
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</em>
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<p>The problem is that we’re losing these important places. And until now, we’ve underestimated how important they are for large, charismatic and ecologically important marine animals. </p>
<h2>Counting wetland megafauna</h2>
<p>Today our review of the connections between marine megafauna and vegetated coastal wetlands was <a href="https://doi.org/10.1016/j.tree.2019.04.004">published in the journal Trends in Ecology and Evolution</a>. As it turns out, far more megafauna species use coastal wetlands than we thought.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275366/original/file-20190520-69195-r18lbn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&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="attribution"><span class="source">Author provided/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Before our review, the number of marine megafauna species known to use these habitats was 110, according to the <a href="https://iucn.org">International Union for Conservation of Nature</a> (IUCN) <a href="https://www.iucnredlist.org/">Red List</a>, which assesses species’ conservation status. </p>
<p>We identified another 64 species from 340 published studies, bringing the total number to 174 species. This means 13% of all marine megafauna use vegetated coastal wetlands.</p>
<p>We predominantly documented these habitat associations by electronic tracking, direct observation or from analysing stomach contents or chemical tracers in animal tissues. </p>
<p>Less commonly, acoustic recordings and <a href="https://www.youtube.com/watch?v=8nmmYAtmag0">animal-borne video</a> studies – strapping a camera on the back of turtle, for instance – were used.</p>
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<h2>Deepening our understanding of how species use their habitats</h2>
<p>In recent weeks, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) released a damming <a href="https://www.ipbes.net/news/ipbes-global-assessment-summary-policymakers-pdf">assessment</a> of humanity’s stewardship of the natural world. Up to 1 million species were reported to be facing extinction within decades.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/revolutionary-change-needed-to-stop-unprecedented-global-extinction-crisis-116166">'Revolutionary change' needed to stop unprecedented global extinction crisis</a>
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<p>We need to dramatically change how we relate to and engage with species and their habitats, if we are to fix this problem. </p>
<p>But the question is, how can we make global change real, relevant and feasible at local and regional scales? And, as the international community rises to this challenge, what information is needed to support such efforts?</p>
<p>Our study suggests a critical first step to addressing the global biodiversity crisis is to deepen our understanding of links between species and their habitats. We also need to elevate how the evidence is used to both assess extinction risk and prioritise, plan and deliver conservation actions.</p>
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<a href="https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275563/original/file-20190521-23841-16dho2c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A juvenile lemon shark swimming in mangroves. More than half of the world’s coastal wetlands have been lost.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<p>More than <a href="http://www.publish.csiro.au/mf/MF14173">half of all coastal wetlands have been lost globally</a> and the rest are at risk from a range of serious threats, including deforestation. There is an urgent need to limit and reverse the loss of coastal wetlands to stop biodiversity loss, protect communities and tackle climate change.</p>
<p>Targeting places where high rates of mangrove loss intersect with threatened megafauna could lead to more efficient and effective conservation outcomes. Southeast Asia, Mexico and northern Brazil are <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/geb.12449">such places</a>. </p>
<p>In Southeast Asia, for example, the world’s largest mangrove forest is losing trees at a rate far exceeding global averages, largely due to <a href="https://www.pnas.org/content/113/2/344.short">aquaculture and agriculture</a>. This is threatening the critically endangered green sawfish, which relies on these mangrove habitats.</p>
<h2>Habitats should always be considered in assessments</h2>
<p>The IUCN Red List assesses the extinction risk for almost 100,000 species. It provides comprehensive information on global conservation statuses, combining information on population sizes, trends and threats. </p>
<p>The wealth of data collected during species’ assessments, including habitat associations of threatened species, is one of the Red List’s most valuable features. </p>
<p>But our study shows many known associations are yet to be included. And for more than half of the assessments for marine megafauna, habitat change is yet to be listed as a threat.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275557/original/file-20190521-23838-1n7q4w3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘Proportion species’ refers to all species within key taxonomic groups that are associated with coastal wetlands.</span>
<span class="attribution"><span class="source">Author supplied</span></span>
</figcaption>
</figure>
<p>This is concerning because assessments that overlook habitat associations or lack sufficient detail, may not allow conservation resources be directed at the most effective recovery measures. </p>
<p>But it’s also important to note habitat associations have varying strengths and degrees of supporting evidence. For example, a population of animals shown to consume substantial amounts of seagrass is clearly a stronger ecological link than an individual simply being observed above seagrass.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275564/original/file-20190521-23835-1q3yrip.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The data on habitat associations must be strengthened in species assessments.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>In our paper, we propose a simple framework to address these issues, by clarifying habitat associations in conservation assessments. Ideally, these assessments would include the following:</p>
<ul>
<li>list all habitat types the species is known to associate with</li>
<li>indicate the type of association (occurrence, grazing, foraging or breeding)</li>
<li>cite the source of supporting evidence</li>
<li>provide an estimate of the level of habitat dependence.</li>
</ul>
<h2>Data for decision making</h2>
<p>Habitat loss is accelerating a global extinction crisis, but the importance of coastal habitats to marine megafauna has been significantly undervalued in assessments of extinction risk.</p>
<p>We need to strive to protect remaining coastal wetland habitats, not only for their ecological role, but also for their economic, social and cultural values to humans. We can do this by strengthening how we use existing scientific data on habitat associations in species assessments and conservation planning.</p><img src="https://counter.theconversation.com/content/116177/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Sievers receives funding from a private philanthropic trust. </span></em></p><p class="fine-print"><em><span>Rod Connolly receives funding from the Australian Research Council, Australia's National Environmental Science Program, a private philanthropic trust, and the Queensland State Government.</span></em></p><p class="fine-print"><em><span>Tom Rayner receives funding from a private philanthropic trust and is a member of the political party Independents for Climate Action Now.</span></em></p>Far more megafauna species use coastal wetlands than we thought. And it affects the way we need to address the extinction crisis.Michael Sievers, Research Fellow, Global Wetlands Project, Australia Rivers Institute, Griffith UniversityRod Connolly, Professor in Marine Science, Griffith UniversityTom Rayner, Science Communicator, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1033642018-11-01T19:07:52Z2018-11-01T19:07:52ZSeagrass, protector of shipwrecks and buried treasure<figure><img src="https://images.theconversation.com/files/237444/original/file-20180921-129865-14kzjwc.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C1760%2C990&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nature's bank vault.</span> <span class="attribution"><span class="source">Julius Glampedakis</span>, <span class="license">Author provided</span></span></figcaption></figure><p>For more than 6,000 years, seagrass meadows in Australia’s coastal waters have been acting as security vaults for priceless cultural heritage. </p>
<p>They’ve locked away thousands of shipwrecks in conditions perfect for preserving the fragile, centuries-old timbers of early European and Asian explorers, and could even hold secrets of seafaring by Aboriginal Australians. </p>
<p>Seagrass meadows accumulate marine sediments beneath their leaves, slowly burying and safeguarding wrecks in conditions that museum curators can only dream of. It’s a process that takes centuries, as mats of seagrass and sediments cover the wrecks and all their buried treasure.</p>
<p>Seagrass sedimentary deposits also hold archives of wider environmental change over millennia and are important sinks for atmospheric carbon dioxide, known as Blue Carbon. </p>
<p>But human development, climate change and storms are <a href="https://academic.oup.com/bioscience/article/56/12/987/221654">threatening fragile seagrass meadows around the world</a>, and that risks the loss of the important cultural heritage they protect as well as some of the world’s most productive marine ecosystems.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dugong-and-sea-turtle-poo-sheds-new-light-on-the-great-barrier-reefs-seagrass-meadows-95143">Dugong and sea turtle poo sheds new light on the Great Barrier Reef's seagrass meadows</a>
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<p>Our <a href="https://link.springer.com/article/10.1007/s13280-018-1083-2">research</a>, carried out by an international team of scientists in Australia, Denmark, Saudi Arabia and Greece, shows that seagrass meadows, hidden beneath our oceans, gradually build up the seafloor over millennia by trapping sediments and particles and depositing those materials as they grow. </p>
<p>The organic and chemical structure of seagrass sedimentary deposits is key to its ability to protect shipwrecks and submerged prehistoric landscapes. These structures are extraordinarily resistant to decay, creating thick sediment deposits that seal oxygen away from archaeological sites, preventing ships’ timbers and other materials from rotting away. </p>
<p>Seagrass meadows are under environmental stress due to climate change, storms and human activity. Recent disturbances and losses have exposed shipwrecks and archaeological artefacts that were previously preserved beneath the sediment. Once the protective cover of seagrass is gone, the ships and other sites begin to break down. If you lose seagrass, you lose cultural heritage. </p>
<p>Seagrass meadow losses in the Mediterranean have exposed Phoenician, Greek and Roman ships and cargo, many of which are thousands of years old. Unless these effects can be stemmed, the frequency of exposures is likely to increase. This has already put European archaeologists and marine scientists in a race against the clock. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=674&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=674&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=674&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=847&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=847&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243473/original/file-20181101-83638-1o00gcv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=847&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Roman amphorae from a late Roman shipwreck in South Prasonisi islet, Greece, surrounded by seagrass meadows.</span>
<span class="attribution"><span class="source">T. Theodoulou.</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Around <a href="http://www.environment.gov.au/heritage/historic-shipwrecks/australian-national-shipwreck-database">7,000 shipwrecks</a> are thought to lie in Australia’s coastal waters. Seagrass disturbance led to the unearthing in 1973 of the <a href="http://museum.wa.gov.au/research/research-areas/maritime-archaeology/treasures-from-the-deep/james-matthews">James Matthews</a>, a former slave ship that sank in 1841 in Cockburn Sound, Western Australia, and the <a href="https://www.abc.net.au/news/2017-05-30/survival-story-sydney-coves-shipwrecked-sailors/8536714">Sydney Cove</a>, which ran aground off Tasmania’s Preservation Island in 1797, forcing survivors to walk 700km to Sydney. </p>
<p>Artefacts and pieces of the James Matthews’ hull have been recovered and studied at the WA Museum. Meanwhile, the recovery of beer bottles from the Sydney Cove has led, remarkably, to 220-year-old brewing yeast being cultivated and used to create a new beer – fittingly enough called <a href="https://www.jamessquire.com.au/craft-beer/the-wreck-preservation-ale/">The Wreck</a>.</p>
<h2>Revealing wrecks</h2>
<p>We and our colleagues are aiming to match shipwreck data with seagrass meadow maps. From there, we hope new acoustic techniques for below-seabed imaging will allow exploration of underwater sites without disturbing the overlying seagrass meadows. Controlled archaeological excavation could then be undertaken to excavate, document and preserve sites and artefacts. </p>
<p>We also believe there’s significant potential to find archaeological heritage of early Indigenous Australians buried and preserved in seagrass meadows. Sea level around Australia rose around 6,000 years ago, potentialy submerging ancient indigenous settlements located in coastal areas, which may now be covered by seagrass.</p>
<p>The danger of not putting these protections in place is evidenced by treasure-hunters off the Florida coast, who have adopted a destructive technique called “mailboxing” to <a href="https://books.google.es/books?hl=en&lr=&id=QI6BNveaUAoC&oi=fnd&pg=PA1&dq=Heritage+Resources+Law:+Protecting+the+Archeological+and+Cultural+Environment&ots=OYHK-vqdDY&sig=OHGfsNVC22phfWc74KTbVCUR3Nk#v=onepage&q=Heritage%20Resources%20Law%3A%20Protecting%20the%20Archeological%20and%20Cultural%20Environment&f=false">search for gold in Spanish galleons</a>. This involves punching holes into sediment to find and then pillage wrecks, an action that damages seagrass meadows and archaeological remains.</p>
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Read more:
<a href="https://theconversation.com/we-desperately-need-to-store-more-carbon-seagrass-could-be-the-answer-105524">We desperately need to store more carbon – seagrass could be the answer</a>
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<p>The accumulated sediments in seagrass meadows could also help build a record of environmental conditions, including fingerprints of human culture. These archives can be used to reconstruct prehistoric changes in land use and agriculture, mining and metallurgical activities, impacts of human activities on coastal ecosystems, and changes associated with colonisation events by different cultures. Think of it as a coastal equivalent to <a href="https://theconversation.com/chasing-ice-how-ice-cores-shape-our-understanding-of-ancient-climate-55235">polar ice cores</a>. Seagrass records could even help us understand, predict and manage the effects of current environmental changes.</p>
<p>But to do all this, we first need to realise what a truly valuable resource seagrass is. Granted, it doesn’t look spectacular, but it can do some pretty spectacular things – from sucking carbon out of the skies, to underpinning entire ecosystems, and even guarding buried treasure.</p><img src="https://counter.theconversation.com/content/103364/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Oscar Serrano receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>David John Gregory has received funding from the Danish Ministry of Culture, and the European Union, and is a member of Europa Nostra, a non-profit lobbying body that promotes cultural heritage within the EU.</span></em></p><p class="fine-print"><em><span>Carlos M. Duarte, Dorte Krause-Jensen, and Eugenia Apostolaki do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The sediments that accumulate beneath seagrass meadows can act as secure vaults for shipwrecks and other precious artefacts, by stopping water and oxygen from damaging the delicate timbers.Oscar Serrano, Doctor of Global Change, Edith Cowan UniversityCarlos M. Duarte, Adjunct professor, King Abdullah University of Science and TechnologyDavid John Gregory, Senior Researcher, National Museum of DenmarkDorte Krause-Jensen, Senior Researcher, Marine Ecology, Aarhus UniversityEugenia Apostolaki, Researcher, Institute of Oceanography, Hellenic Centre for Marine ResearchLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/951432018-05-24T20:07:12Z2018-05-24T20:07:12ZDugong and sea turtle poo sheds new light on the Great Barrier Reef’s seagrass meadows<p>Just like birds and mammals carrying seeds through a rainforest, <a href="https://www.nature.com/articles/s41598-017-04421-1">green sea turtles and dugong</a> spread the seeds of <a href="http://ocean.si.edu/seagrass-and-seagrass-beds">seagrass plants</a> as they feed. Our team at James Cook University’s <a href="https://research.jcu.edu.au/tropwater">TropWATER Centre</a> has uncovered a unique relationship in the seagrass meadows of the Great Barrier Reef.</p>
<p>We followed feeding sea turtle and dugong, collecting samples of their floating faecal matter. Samantha then had the unenviable job of sifting through hundreds of smelly samples to find any seagrass seeds. These seeds range in size from a few centimetres to a few millimetres, and therefore can require the assistance of a microscope to be found. Once any seeds were found, they were stained with a chemical dye (Tetrazolium) to see if they were still viable (capable of growing).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/220051/original/file-20180523-51115-vt5hm0.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">PhD candidate Samantha Tol holding dugong poo collected from Cleveland Bay in Townsville.</span>
<span class="attribution"><span class="source">TropWATER, JCU</span></span>
</figcaption>
</figure>
<h2>Why is this important for turtles and dugong?</h2>
<p><a href="https://www.nationalgeographic.com/animals/reptiles/g/green-sea-turtle/">Green sea turtles</a> and <a href="https://www.nationalgeographic.com/animals/mammals/d/dugong/">dugong</a> are iconic animals on the reef, and seagrass is their food. Dugong can eat as much as 35 kilograms of wet seagrass a day, while sea turtles can eat up to 2.5% of their body weight per day. Without productive seagrass meadows, they would not survive. </p>
<p>This relationship was highlighted in 2010-11 when heavy flooding and the impact of tropical cyclone Yasi led to drastic seagrass declines in north Queensland. In the year following this seagrass decline there was a spike in the number of <a href="https://www.telegraph.co.uk/news/worldnews/australiaandthepacific/australia/8753630/Mass-starvation-of-dugongs-and-turtles-on-Great-Barrier-Reef.html">starving and stranded sea turtles and dugong</a> along the entire Queensland coast.</p>
<p>The <a href="https://research.jcu.edu.au/tropwater/research-programs/seagrass-ecology-1/seagrass-ecology">seagrass team at James Cook University</a> has been <a href="https://eatlas.org.au/map/gbr-seagrass">mapping</a>, monitoring and researching the health of the Great Barrier Reef seagrasses for more than 30 years. While coral reefs are more attractive for tourists, the <a href="https://www.sciencedirect.com/science/article/pii/S0272771414002078?via%3Dihub">Great Barrier Reef World Heritage Area</a> actually contains a greater area of seagrass than coral, encompassing around 20% of the world’s seagrass species. Seagrass ecosystems also maintain vibrant marine life, with many fish, crustaceans, sea stars, sea cucumbers, urchins and many more marine animals calling these meadows their home.</p>
<p>These underwater flowering plants are a <a href="https://academic.oup.com/bioscience/article/56/12/987/221654">vital component</a> of the reef ecosystem. Seagrasses stabilise the sediment, sequester large amounts of carbon from the atmosphere and <a href="http://science.sciencemag.org/content/355/6326/731">filter the water</a> before it reaches the coral reefs. Further, the seagrass meadows in the Great Barrier Reef support one of the largest populations of sea turtles and dugong in the world.</p>
<h2>Seagrass meadows are more connected than we thought</h2>
<p>Samantha’s research was worth the effort. There were seeds of at least three seagrass species in the poo of both sea turtles and dugong. And lots of them – as many as two seeds per gram of poo. About one in ten were viable, meaning they could grow into new plants. </p>
<p>Based on estimates of the number of animals in the coastal waters, the time it takes for food to pass through their gut, and movement data collected from animals fitted with satellite tags, there are potentially as many as 500,000 viable seeds on the move each day in the Great Barrier Reef. These seeds can be transported distances of up to 650km in total.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/220052/original/file-20180523-51105-16my7yr.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">Green Island seagrass meadow exposed at low tide.</span>
<span class="attribution"><span class="source">TropWATER, JCU</span></span>
</figcaption>
</figure>
<p>This means turtles and dugong are <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ddi.12479">connecting distant seagrass meadows</a> by transporting seeds. Those seeds improve the genetic diversity of the meadows and may help meadows recover when they are damaged or lost after cyclones. These animals help to protect and nurture their own food supply, and in doing so make the reef ecosystem around them more resilient. </p>
<h2>Understanding recovery after climate events</h2>
<p>Seagrass meadows have been under stress in recent years. A series of <a href="https://link.springer.com/article/10.1007/s12038-015-9516-6">floods and cyclones</a> has left meadows in poor condition, and recovery has been <a href="https://www.sciencedirect.com/science/article/pii/S0025326X1400109X?via%3Dihub">patchy and site-dependent</a>. </p>
<p>This research shows that these ecosystems have pathways for recovery. Provided we take care with the environment, seagrasses may yet recover without direct human intervention. </p>
<p>This work emphasises how much we still have to learn about how the reef systems interconnect and work together – and how much we need to protect every part of our marvellous and amazing reef environment.</p><img src="https://counter.theconversation.com/content/95143/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Tol receives funding from various research grants and income from coastal projects and consultancies.</span></em></p><p class="fine-print"><em><span>Paul York receives funding from various research grants and income from coastal projects and consultancies.</span></em></p><p class="fine-print"><em><span>Rob Coles receives funding from various research grants and income from coastal projects and consultancies. </span></em></p><p class="fine-print"><em><span>Alana Grech 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>New research highlights the role of sea turtles and dugong in the dispersal of seeds and maintenance of seagrass meadows, an important marine habitat and the primary food source for both animals.Samantha J Tol, PhD Candidate, James Cook UniversityAlana Grech, Assistant Director, ARC Centre of Excellence for Coral Reef Studies, James Cook UniversityPaul York, Senior Research Scientist in Marine Biology, James Cook UniversityRob Coles, Team leader, Seagrass Habitats, TropWATER, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/965612018-05-21T09:29:58Z2018-05-21T09:29:58ZLoss of marine habitats is threatening the global fishing industry – new research<figure><img src="https://images.theconversation.com/files/219569/original/file-20180518-42245-18jkw6c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fishing ships in Lauwersoog, The Netherlands. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fishing-ships-lauwersoog-which-harbours-one-789709630?src=1pZV_51sQhTbbT1o8qDMyQ-1-63">Rudmer Zwerver/Shutterstock</a></span></figcaption></figure><p>Seafood consumption is both a love and a necessity for hundreds of millions of people worldwide. And its supply is a key part of maintaining food security for the whole planet. But during a time of rapid population growth and increasing demand, stocks of wild fish and invertebrates (such as mussels and prawns) <a href="http://www.fao.org/3/a-i5555e.pdf">are declining</a>. </p>
<p>The problem is that policies and plans designed to make sure there are enough fish and invertebrates almost exclusively target fishing activity. But we also need to protect the critical habitats that are essential for the sustainability of these stocks and fisheries.</p>
<p>Most species that are fished require more than a single habitat to live and thrive. Atlantic cod (<em>Gadus morhua</em>), for example, spends its adult life shoaling in deep water where it lives, feeds and spawns. But juveniles <a href="https://www.sciencedirect.com/science/article/pii/S235198941400050X">require more stable habitat</a> such as seagrass meadows. So, if we want to manage fish and invertebrate stocks for sustainability reasons, it is essential to protect the supporting habitats of targeted species. </p>
<p>Seagrass meadows are just one of these critical habitats. These large areas of marine flowering plants are abundant in shallow seas on all continents except Antarctica. They support biodiversity and in turn the productivity of the worlds fisheries. As seagrass meadows occur from the intertidal – the area exposed by the daily ebb of the tide – to about a depth of 60 metres in clear waters, they are an easily exploitable fishing habitat. </p>
<p>Though it is clear that <a href="https://theconversation.com/seagrass-is-a-marine-powerhouse-so-why-isnt-it-on-the-worlds-conservation-agenda-66503">seagrasses are a vital part of ocean ecosystems</a>, until now, there has been no information on the role that meadows play in supporting the productivity of world fisheries. But we have now published the <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/conl.12566">first quantitative global evidence</a> on the significant roles that seagrasses play.</p>
<h2>Habitats and fisheries</h2>
<p>Nursery grounds in seagrass meadows are a safer, less exposed, environment for eggs to be laid and young animals to find food and protection from predators as they grow. The very fact that they are there means that there are places for commercial fish stocks such as tiger prawns, conch, Atlantic cod and white spotted spinefoot to be caught by global fisheries. In fact, a fifth of the world’s most landed fish – including Atlantic cod and Walleye pollock – <a href="https://onlinelibrary.wiley.com/journal/1755263x#">benefit from the persistence</a> of extensive seagrass meadows.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219631/original/file-20180519-42210-19px09z.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">Many seagrass meadows are visited at low tide for the collection of animals such as sea cucumbers and clams.</span>
<span class="attribution"><span class="source">RKF Unsworth</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But it is not just large-scale fishing industries that benefit from the presence of seagrass meadows. As they are an easily accessible fishing ground, small scale artisanal and subsistence fisheries around the world also use them. </p>
<p>Seagrass is also essential for communities that take part in gleaning – fishing for invertebrates such as sea cucumbers in water that is shallow enough to walk in. This is often done by women and children, and provides a source of essential protein and income for some of the most vulnerable people in tropical coastal communities. It is a common and increasingly visible activity, but it is not usually included in fishery statistics and rarely considered in resource management strategies.</p>
<p>And the benefits of seagrasses don’t only lie in the meadows themselves, their presence supports nearby fishing areas, as well as deep water habitats. They do this by creating expansive areas rich in fauna, from which there are vast quantities of living material, organic matter and associated animal biomass that supports other fisheries. Seagrasses also promote the health of connected habitats (like coral reefs), and have the capacity to support whole food webs in deep sea fisheries.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1885&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1885&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219709/original/file-20180521-78999-1kdklap.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1885&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How seagrass supports the world’s fisheries.</span>
<span class="attribution"><span class="source">Unsworth et al.</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The coastal distribution of seagrass means that it is vulnerable to a multitude of threats from <a href="https://theconversation.com/sewage-and-livestock-waste-is-killing-britains-seagrass-meadows-new-study-91805">both land</a> and sea. These include land runoff, coastal development, boat damage and trawling. On a global scale, <a href="http://www.pnas.org/content/106/30/12377">seagrass is rapidly declining</a>, and when seagrass is lost associated fisheries and their stocks are likely to become compromised with profound and <a href="https://www.sciencedirect.com/science/article/pii/S0304380006000603">negative economic consequences</a>. </p>
<p>The importance of seagrass meadows for fisheries productivity and hence food security is not reflected by the policies currently in place. These are urgently needed to continue enjoying the benefits that healthy and productive seagrass meadows provide. </p>
<p>Fisheries management must be broadened from just targeting fishing activity to also targeting the habitats on which fisheries depend. Awareness of the role of seagrass in global fisheries production – and, so, food security – must be central to any policy, and major manageable threats to seagrass, such as declining water quality, must be dealt with. </p>
<p>Seagrass can be a resilient and supportive habitat – but only if we take action to continue to enjoy the benefits it provides.</p><img src="https://counter.theconversation.com/content/96561/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leanne Cullen-Unsworth is co-director of the marine conservation charity Project Seagrass</span></em></p><p class="fine-print"><em><span>Lina Mtwana Nordlund receives funding from The Swedish Research Council for Environment, Agricultural Sciences and Spatial Plannings. Dr Nordlund is the treasurer of the World Seagrass Association, and coordinator of the Indo-Pacific Seagrass Network. </span></em></p><p class="fine-print"><em><span>Richard K.F. Unsworth is a founding director of the marine conservation charity Project Seagrass.</span></em></p>Seagrass meadows play a significant role in supporting world fishery productivity.Leanne Cullen-Unsworth, Research Fellow, Cardiff UniversityLina Mtwana Nordlund, Researcher in coastal environmental sciences, Stockholm UniversityRichard K.F. Unsworth, Lecturer, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/918052018-02-14T13:51:50Z2018-02-14T13:51:50ZSewage and livestock waste is killing Britain’s seagrass meadows – new study<figure><img src="https://images.theconversation.com/files/206269/original/file-20180213-44642-1qjmxjh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Microscopic algae smothering seagrass leaves</span> <span class="attribution"><span class="source">Richard Unsworth</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Britain’s seagrass is a refuge for numerous species of fish, stabilises sandy beaches, and helps to lock away the carbon which humans produce. The meadows that surround the country’s coast have been called the “canaries of the sea”, due to their sensitivity to a changing environment. And like a canary in a coal mine, their health can be used as an indicator of the condition of coastal areas.</p>
<p>We know that the seagrass meadows surrounding the UK are in <a href="http://rsos.royalsocietypublishing.org/content/3/1/150596">a perilous state of decline</a>, and our recently published research has now uncovered one of the biggest causes. <a href="https://www.frontiersin.org/articles/10.3389/fpls.2018.00133/full">Our study</a> suggests that a major driver of seagrass decline is nutrient pollution from sewage and livestock waste. </p>
<p>Though a new finding, it sadly comes as no surprise, given that about <a href="https://www.wwf.org.uk/updates/40-rivers-england-and-wales-polluted-sewage">40% of rivers</a> in England and Wales are polluted with sewage.</p>
<p>This nutrient pollution puts the long term viability of seagrass meadows <a href="https://www.sciencedirect.com/science/article/pii/S0025326X15005202">in doubt</a>. Over-enrichment results in the suffocation of seagrass. The nutrients cause microscopic algae – called epiphytes – to smother the seagrass leaves, decreasing their ability to capture light, ultimately killing them, and destroying the habitat for fish and other marine animals.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206304/original/file-20180213-175001-qlw0ng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The seagrass, Zostera marina, covered in epiphytes.</span>
<span class="attribution"><span class="source">Richard Unsworth</span></span>
</figcaption>
</figure>
<p>In addition to this environmental impact, we found that several areas, including the Thames waterway seagrass, and a meadow in Studland Bay, Dorset – which are popular with swimmers and boaters – were considerably enriched in nutrients from sewage, livestock effluent and/or human waste. Despite this, neither location, nor any other we identified with the same problem, were classed as unsuitable for swimmers.</p>
<h2>Outdated treatment</h2>
<p>Clearly, we have a massive problem at hand – but water companies, farmers and the government have not done and are still not doing enough to prevent it.</p>
<p>Though efforts have been made to develop a British marine protected area network, and EU legislation has <a href="https://www.theguardian.com/environment/2016/may/25/95-of-british-beaches-clean-enough-to-swim-eu-tests-show">improved water quality</a> in the last few decades, we have found these initiatives to be insufficient. Ten of the 11 sites we studied were in areas with designated EU protection, but most of these seagrass meadows were still polluted with nutrients derived from urban sewage and livestock waste.</p>
<p>So how has this happened? Analysis of the seagrass tissues points to constant sewage exposure. Old and outdated water treatment facilities are one of the likely culprits, resulting in discharges of untreated sewage during times of heavy rainfall. These are legal, but evidently the capacity of these facilities is insufficient to handle the country’s needs, and waterways are suffering because of it.</p>
<p>There is also the problem of livestock waste. Farming is now one of the UK’s <a href="https://www.thebureauinvestigates.com/stories/2017-08-21/farming-pollution-fish-uk">leading causes of water pollution</a>, and inefficiencies <a href="https://www.theguardian.com/environment/2017/aug/21/serious-farm-pollution-breaches-increase-many-go-unprosecuted">in storage and disposal</a> of slurry mean that it ends up in rivers and coastal waters. </p>
<h2>Local and national</h2>
<p>Evidently, in addition to national and international initiatives, we need to start quickly identifying and understanding all local threats to seagrass. Especially if we are going to harmonise conservation goals with sustainable economic development. Only by finding out specifically where the nutrients affecting seagrass areas have come from can we really start to think about a targeted solution for each meadow.</p>
<p>Unfortunately, to date, the conservation of specific seagrass meadows is rarely based on the explicit consideration of local threats and drivers. Instead, projects focus on conserving seagrass as part of a broader plan, incorporating other specific habitats or species. While this may be effective at dealing with problems such as <a href="http://www.southern-ifca.gov.uk/byelaws#Prohibitionofgathering(seafisheriesresources)inSeagrassBeds">fisheries impacts</a>, and is certainly a step forward for the marine environment, it doesn’t deal with the persistent and chronic problem of pollution – which can go largely unnoticed.</p>
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<p>Poor water quality isn’t just a problem for seagrass in the British Isles, it’s a global concern. But if we want to solve it, we must look beyond “protecting” seagrasses with legislation, and challenge the way we think about marine protection overall. Serious infrastructure changes and better management of river catchments – for example, restoration of riverbanks – are vital if we are going to develop long term waste water management plans that span both land and sea.</p><img src="https://counter.theconversation.com/content/91805/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Benjamin L. Jones is a founding director of the marine conservation charity Project Seagrass, and received funded from the Welsh Government Ecosystem Resilience Fund, SEACAMS Project and the Milford Haven Port Authority to conduct this study.</span></em></p><p class="fine-print"><em><span>Leanne Cullen-Unsworth is co-director and trustee of Project Seagrass</span></em></p><p class="fine-print"><em><span>Richard K.F. Unsworth is a founding director of the marine conservation charity Project Seagrass, and was the principal researcher funded from the Welsh Government Ecosystem Resilience Fund, SEACAMS Project and the Milford Haven Port Authority to conduct this study.</span></em></p>The ‘canaries of the sea’ are sending a worrying message about the health of our oceans.Benjamin L.H. Jones, Research Associate, Cardiff UniversityLeanne Cullen-Unsworth, Research Fellow, Cardiff UniversityRichard K.F. Unsworth, Research Officer, Swansea UniversityLicensed as Creative Commons – attribution, no derivatives.