tag:theconversation.com,2011:/uk/topics/shellfish-6218/articlesShellfish – The Conversation2023-09-28T15:52:22Ztag:theconversation.com,2011:article/2134042023-09-28T15:52:22Z2023-09-28T15:52:22ZI’m a microbiologist and here’s what (and where) I never eat<figure><img src="https://images.theconversation.com/files/550869/original/file-20230928-17-d1ixap.jpg?ixlib=rb-1.1.0&rect=20%2C0%2C6689%2C4476&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/chafing-dish-food-1020163570">Alex Andrei/Shutterstock</a></span></figcaption></figure><p>Every year, around <a href="https://www.ukri.org/news/food-safety-network-to-tackle-9-billion-food-poisoning-challenge/#:%7E:text=Food%20poisoning%20key%20facts%3A,foodborne%20illness%20in%20the%20UK">2.4 million people</a> in the UK get food poisoning – mostly from viral or bacterial contamination. Most people recover <a href="https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/food-poisoning/">within a few days without treatment</a>, but <a href="https://bmjopengastro.bmj.com/content/7/1/e000377">not all are that lucky</a>.</p>
<p>As a microbiologist, I’m probably more acutely aware of the risk of food-borne infections than most. Here are some of the things I look out for.</p>
<h2>Eating outdoors</h2>
<p>I rarely eat alfresco – whether picnics or barbecues – as the risk of food poisoning goes up when food is taken outdoors. </p>
<p>Keeping your hands clean when handling food is key to not getting sick, but how often do you find hot running water and soap in a park or on a beach? You can use alcohol hand gels (they’re better than nothing), but they don’t kill all germs. </p>
<p>Also, food tends to attract an array of flying and crawling critters, such as flies, wasps and ants, all of which can transfer germs, including <em>E coli</em>, <em>Salmonella</em> and <em>Listeria</em>, to your food. </p>
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Read more:
<a href="https://theconversation.com/a-fruit-fly-has-landed-in-your-wine-is-it-ok-to-drink-211847">A fruit fly has landed in your wine – is it OK to drink?</a>
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<p>Keeping perishable food cold and covered is essential as germs can double in numbers if food is allowed to warm up to 30°C for more than a few hours. For barbecues, meat needs to be thoroughly cooked, and a meat thermometer is a good investment to avoid food poisoning. Do not eat meat if its internal temperature is <a href="https://www.betterhealth.vic.gov.au/health/healthyliving/food-safety-outdoors">less than 70°C</a>. </p>
<h2>Buffets</h2>
<p>Knowing what food-related conditions bacteria prefer to grow in, I am very mindful of the microbiological safety of hot and cold buffet displays. </p>
<p>Indoors, food can be exposed to contamination from insects, dust and above all, people. Food poisoning is, therefore, an inevitable risk when dining at a <a href="https://www.fda.gov/food/buy-store-serve-safe-food/serving-safe-buffets">buffet</a>. </p>
<p>Contamination comes from buffet visitors touching food, and germs can be sprayed on to buffets from people sneezing or coughing close to the food. Even indoors, one must consider contamination by insects, such as flies or wasps, settling on the uncovered food. Also, germs may be deposited from the air, which is rich in bacteria, fungi and viruses. </p>
<p>I always look at the clock when I’m at a buffet as there is a <a href="https://www.cdc.gov/foodsafety/serving-food-safely.html">two-hour catering rule</a>: perishable food will become unsafe to eat within two hours if not kept covered and refrigerated. The problem is buffets tend to be laid out before you arrive, so it is difficult to tell if the platters of cooked meat, seafood, salads, desserts and appetisingly arranged fruit and vegetables will have been sitting for more than two hours when you come to eat them. </p>
<p>For hot buffets, such as those served at breakfast in hotels, I always avoid lukewarm food, as bacteria that cause food poisoning can grow quickly when food is <a href="https://www.fda.gov/food/buy-store-serve-safe-food/serving-safe-buffets">kept at less than 60°C</a>. Hot food should be served hot, that is at a temperature of at least 60°C. If there is any uncertainty about the safety of the food on offer, I reluctantly breakfast on freshly toasted bread and individually packaged marmalade. </p>
<h2>Oysters</h2>
<p>There are some foods I never eat, and raw shellfish, such as oysters, is one of them. This is because oysters are filter feeders and can concentrate germs, such as <em>Vibrio</em> and norovirus, in their tissue. </p>
<p>A <em>Vibrio</em>-contaminated oyster does not look, smell, or taste different, but can still make you very ill. The US Centers for Disease Control and Prevention estimates that about 80,000 people get <em>Vibrio</em> infections from raw oysters, and in the US alone 100 people <a href="https://www.cdc.gov/foodsafety/communication/oysters-and-vibriosis.html">die from vibriosis</a> each year.</p>
<p>It is also possible to pick up food poisoning from eating any raw shellfish (clams, mussels, whelks, cockles). I only eat shellfish that are well-cooked because heat effectively kills harmful germs. </p>
<h2>Bagged salads</h2>
<p>I never eat bagged salads, largely because one of my research areas is fresh salad safety. It has been found that bagged lettuce can contain food poisoning germs such as <em>E coli</em>, <em>Salmonella</em> and <em>Listeria</em>. </p>
<p>My research group <a href="https://journals.asm.org/doi/10.1128/aem.02416-16">has found</a> that these pathogens grow more than a thousand times better when given juices from salad leaves, even if the salad bag is refrigerated. Worryingly, the same germs use the salad juices to become more virulent, and so better at causing an infection.</p>
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Read more:
<a href="https://theconversation.com/the-sniff-test-is-not-reliable-for-food-safety-heres-why-211808">The sniff test is not reliable for food safety – here's why</a>
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<p>For those salad lovers alarmed by this information, most bagged salads are safe if stored refrigerated, washed well before use (even ready-to-eat salad should be washed) and eaten as soon as possible after buying it. </p>
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<img alt="An open bag of lettuce." src="https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550872/original/file-20230928-15-irzk45.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">If there are salad ‘juices’, throw it out.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/open-bag-salad-lettuce-carrots-white-528025258">Noel V. Baebler/Shutterstock</a></span>
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<h2>Cooking practices</h2>
<p>In terms of cooking practices, I have a list of dos and don’ts. </p>
<p>For perishable foods, I regularly check use-by dates, but if it is before the expiry date and the food package looks swollen, or when opened the food looks or smells different than expected, I throw it in the bin as it could be contaminated.</p>
<p>I never use the same chopping boards for raw and cooked foods, and washing my hands before and after handling food is instinctual. </p>
<p>One of my “never do” practices is reheating cooked rice. This is because uncooked rice can contain spores of <em>Bacillus cereus</em>, a food-poisoning germ. </p>
<p>Although the <em>Bacillus</em> cells are killed by cooking, the spores survive. If the rice is left to cool and sit at room temperature, <a href="https://www.nhs.uk/common-health-questions/food-and-diet/can-reheating-rice-cause-food-poisoning/#:%7E:text=Yes%2C%20you%20can%20get%20food,been%20stored%20before%20it%E2%80%99s%20reheated">the spores grow into bacteria</a>, which will increase in numbers quickly as rice is a good <em>Bacillus</em> culture medium when at room temperature. </p>
<p>The rice-cultured <em>Bacillus</em> can produce toxins that, within a few hours of ingestion, can cause vomiting and diarrhoea lasting up to 24 hours.</p>
<h2>Dining out</h2>
<p>I find that having a high level of food safety awareness causes me to be first in line for buffets, to be cautious about eating from breakfast bars, and to watch the clock for how often perishable food is replaced. I never collect “doggy bags” of food leftovers (they have usually exceeded the two-hour time limit), even if they really are intended for a pet. </p>
<p>The benefits of being a microbiologist are that we know how to avoid food poisoning and, in return, people have confidence our cooking is very safe to eat.</p><img src="https://counter.theconversation.com/content/213404/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Primrose Freestone has previously received funding from the BBSRC for her salad research work..</span></em></p>You’ll never look at bagged lettuce the same way again.Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2034912023-06-05T12:09:28Z2023-06-05T12:09:28ZIs there life in the sea that hasn’t been discovered?<figure><img src="https://images.theconversation.com/files/529826/original/file-20230602-17-k2m7hu.jpeg?ixlib=rb-1.1.0&rect=6%2C2%2C1502%2C1002&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Rose-veiled fairy wrasse, a small reef fish discovered in 2022.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Cirrhilabrus_finifenmaa_underwater_photograph_from_Rasdhoo_Atoll,_Maldives_-_Oo_654790.jpg">Luiz A. Rocha/Wikimedia Commons</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&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://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<p>Is there life in the sea that hasn’t been discovered? – Haven W., age 12, McKinney, Texas</p>
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<p>Imagine going to a place on Earth where no one has ever been. There are many locations like that in the ocean, which covers <a href="https://www.usgs.gov/special-topics/water-science-school/science/how-much-water-there-earth">more than 70% of our planet</a>. </p>
<p>In the ocean, creatures live at many different depths, just as animals and birds live at different heights in a forest. Every ocean life form has to find a way to gather nourishment, reproduce and contribute to an ecological community. </p>
<p>The ocean is <a href="https://theconversation.com/how-deep-is-the-ocean-121168">thousands of feet deep in many areas</a> and offers millions of opportunities for life to thrive. Biologists don’t know how many species live in the ocean, but they estimate that <a href="https://oceanservice.noaa.gov/facts/ocean-species.html">fewer than 10% have been described</a>. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CszRZcWPjHH/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Black and white smokers</h2>
<p>Fifty years ago, no one imagined that entire biologic communities were thriving in extreme darkness under the crushing pressures of the deep sea. Then they found them, at spots called <a href="https://oceanservice.noaa.gov/facts/vents.html">hydrothermal vents</a> – first with underwater cameras and thermometers, next by sending humans down in <a href="https://www.whoi.edu/what-we-do/explore/underwater-vehicles/hov-alvin/">Alvin, an underwater vehicle</a>. </p>
<p>The researchers found spots where hot water jetted upward through cracks in the seafloor, like geysers on land. Some of the water was as hot as 750 degrees Fahrenheit (400 degrees Celsius) – more than twice as hot as the oven when you bake a cake. And it was full of dissolved minerals. </p>
<p>As the hot water spilled onto the seafloor, where the water around it was much colder – just 36 F (2 C) – it quickly cooled, and the minerals solidified into stacks that looked like chimneys. Some were tens or hundreds of feet high. </p>
<p>Even in these cold, dark zones, the vents were home to all kinds of living organisms, including giant tube worms, clams, crabs and other species. Sunlight doesn’t reach deep enough in the ocean to serve as an energy source for these communities as it does for ecosystems on land. Instead, these complex ecosystems run on <a href="https://oceanexplorer.noaa.gov/facts/photochemo.html">chemosynthesis</a> – energy from chemical reactions between bacteria and the water. </p>
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<figcaption><span class="caption">Deep-sea biologist Shannon Johnson describes hydrothermal vents and some of the creatures that thrive around them.</span></figcaption>
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<p>Bacteria that lived in the vents use chemicals such as hydrogen sulfide for energy to make carbohydrates. Then larger organisms feed on the bacteria and the creatures they nourish, and in turn are eaten by still larger creatures, creating a food chain.</p>
<p>Scientists first found “white smokers” – underwater vents where the superheated water deposited light-colored minerals, made of calcium and silicon – northeast of the <a href="https://oceanservice.noaa.gov/facts/vents.html">Galapagos Islands in 1977</a>. Then, in 1979, they found “black smokers,” made from darker, metal-rich minerals like iron sulfides, <a href="https://www.whoi.edu/feature/history-hydrothermal-vents/discovery/1979-2.html">at the southern tip of Baja Mexico</a>. </p>
<p>I was working at the Wood Hole Oceanographic Institution, which designed and built Alvin, when black smokers were discovered. The water around the vents was so hot that the plastic tip on Alvin’s external thermometer melted. We were worried for the safety of the researchers and pilot in Alvin because the thick plastic on the viewing portholes was the same composition as the thermometer tip. </p>
<p>But Alvin was well designed, and everyone survived. In fact, Alvin has been updated many times; scientists are still using it to explore deep reaches of the ocean.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Bti1AbFnFuD/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Fluffy crabs and glowing worms</h2>
<p>Every year, scientists discover new marine species. Some swim in deep water or crawl and wiggle near or on the seafloor. Some, like slow-growing bacteria that inhabit the deep ocean crust, barely move at all. </p>
<p>Just in the past two years, researchers have found dozens of new species in the oceans. For example, there’s the “<a href="https://marinespecies.org/aphia.php?p=image&tid=1579238&pic=159908">fluffy” sponge crab (<em>Lamarckdromia beagle</em>)</a>, which decorates its shell with sponges, probably as camouflage from predators. </p>
<p>Another striking find, the <a href="https://www.calacademy.org/press/releases/stunning-new-to-science-fairy-wrasse-is-first-ever-fish-described-by-a-maldivian">Rose-veiled fairy wrasse (<em>Cirrhilabrus finifenmaa</em>)</a>, is a stunning pink reef fish from the Maldives, an island nation in the Indian Ocean.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1637242518550061056"}"></div></p>
<p>In Australia, scientists had been speculating for years about the origin of an unusual shark egg case in their country’s <a href="https://www.csiro.au/en/about/facilities-collections/collections/anfc">National Fish Collection</a>. In May 2023, they identified a new species of shark that produced it: the <a href="https://shark-references.com/species/view/Apristurus-ovicorrugatus">ghost or demon catshark (<em>Apristurus ovicorrugatus</em>)</a>, so called because its eyes have <a href="https://www.cbsnews.com/news/scientists-identify-new-species-of-demon-catshark-with-white-shiny-irises/">spooky-looking white irises</a>. </p>
<p>Three of the most intriguing new species are <a href="https://www.popsci.com/environment/bioluminescent-sea-worm-species-japan/">bioluminescent sea worms</a> that emit a bluish-violet light. The researchers who found the worms in shallow waters near Japan named one <em>Polycirrus Ikeguchi</em>, after a notable Japanese marine biologist named Shinichiro Ikeguchi. They called the other two <em>Polycirrus aoandon</em>, which means “blue lantern ghost,” and <em>Polycirrus onibi</em>, which means “demon fire.” Both names refer to spirits in Japanese folklore.</p>
<p>You can follow new discoveries as they are entered into the <a href="https://www.marinespecies.org/">World Register of Marine Species</a>. With 90% of ocean life still to describe, there are countless new discoveries to be made. </p>
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<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/203491/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Suzanne OConnell does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>From fluffy crabs that wear sea sponge hats to worms that glow in the dark, scientists are constantly finding amazing new life forms in the ocean.Suzanne OConnell, Harold T. Stearns Professor of Earth Science, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2056122023-05-19T14:48:48Z2023-05-19T14:48:48ZCheck your tyres: you might be adding unnecessary microplastics to the environment<figure><img src="https://images.theconversation.com/files/527250/original/file-20230519-19-lbiwoo.jpg?ixlib=rb-1.1.0&rect=0%2C12%2C4288%2C2830&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Antrim coastal road, Northern Ireland.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/eastern-coast-northern-ireland-antrim-coastal-1359226952">Nahlik/Shutterstock</a></span></figcaption></figure><p>Cost-saving measures are key in today’s economic climate. But they can also have a positive impact on minimising your environmental footprint. A prime example is maintaining your cars’ optimal tyre pressure.</p>
<p>Over time, tyres naturally lose pressure – typically by around <a href="https://www.sciencedirect.com/science/article/pii/S0301421506003090">1 psi a month</a>. As pressure decreases, the tyre becomes flatter, causing increased friction between the road and the tyre itself. This heightened friction results in greater drag, reducing the lifespan of your tyre and meaning more fuel is needed for travel.</p>
<p>But driving with flatter tyres also <a href="https://www.actu-environnement.com/media/pdf/news-36643-rapport-ocde-emissions-hors-echappement.pdf">increases the number of tyre wear particles</a> that are released into the environment. These particles – less than a millimetre in size – have been classified as microplastics due to their chemical makeup.</p>
<p>Tyre wear stands out as a major source of microplastic pollution. Globally, each person is responsible for around 1kg of microplastic pollution from tyre wear released into the environment on average each year – with even higher rates observed in <a href="https://www.sciencedirect.com/science/article/pii/S0048969720313358">developed nations</a>. </p>
<p>It is estimated that between <a href="https://www.sciencedirect.com/science/article/pii/S0048969720313358">8% and 40% of these particles</a> find their way into surface waters such as the sea, rivers and lakes through runoff from road surfaces, wastewater discharge or even through <a href="https://www.sciencedirect.com/science/article/pii/S0025326X21009310">airborne transport</a>.</p>
<p>However, tyre wear microplastics have been largely overlooked as a microplastic pollutant. Their dark colour makes them difficult to detect, so these particles can’t be identified using the traditional spectroscopy methods used to identify other more colourful plastic polymers. </p>
<p>To understand the extent of tyre wear pollution, scientists have instead had to figure out ways to identify the chemicals that are associated with tyres in water samples. Using these methods, tyre wear chemicals have been found in <a href="https://pubs.acs.org/doi/abs/10.1021/es400871j">97% of river and estuary samples</a> tested in Europe, the US and Japan. </p>
<p>And yet, we still know relatively little about the effects of tyre wear pollutants on the health of marine animals. This is what my colleagues and I set out to discover in a <a href="https://www.sciencedirect.com/science/article/pii/S0269749122014580?via%3Dihub#bib2">recent study</a>. </p>
<h2>Filter feeders</h2>
<p>Our study focused on two species common to estuaries in the north-east Atlantic – a bivalve called the <a href="https://www.marlin.ac.uk/species/detail/1507">peppery furrow shell</a> and the <a href="https://www.marlin.ac.uk/species/detail/1426">ragworm</a>. The bivalve feeds by filtering organic particles from the water and sediment. </p>
<p>The worm is primarily carnivorous, eating small creatures that live on the seafloor, but it also obtains some of its food from seawater and sediment. Both animals are likely to be exposed to tyre wear particles and the potential toxins they contain.</p>
<p>We carried out two experiments. In the first, we exposed these animals to high concentrations of tyre particles (10%) mixed into the sediment they burrow in for three days to see whether they ingested them. We then dissected the animals and counted any tyre particles within their gastrointestinal tract.</p>
<p>Because the tyre particles are rubbery, and could be compressed with a needle, we were able to analyse them under a microscope. We found that the worms only consumed small concentrations of tyre particles (at most 33). </p>
<p>By contrast, the bivalves had large quantities of both sediment and tyre particles in their stomachs – one bivalve had consumed over 1,000 tyre particles.</p>
<figure class="align-center ">
<img alt="A man collecting small animals from the bed of a river estuary." src="https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/526795/original/file-20230517-11772-dlv1zx.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">Collecting animals in the Tamar Estuary, Cornwall.</span>
<span class="attribution"><span class="source">Plymouth Marine Laboratory</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>In the second experiment, we exposed the animals to three concentrations of tyre particles (0.2%, 1% and 5%) mixed into the sediment for three weeks. We did this to understand how this exposure affected their health. </p>
<p>We measured a number of health indicators, ranging from cellular to organism level. Bivalve health was affected at all of the concentrations tested, with feeding and burrowing impaired even at low concentrations (0.2%). At a high concentration (5%), we observed a decrease in protein content and an increase in <a href="https://www.healthline.com/health/oxidative-stress">oxidative stress</a>.</p>
<p>Oxidative stress occurs when there are too many unstable molecules called free radicals in the body. These free radicals can lead to cell and tissue damage. </p>
<p>At low concentrations, the health of the worm was not affected. But we did observe a decrease in protein and energy content and signs of oxidative stress as exposure to tyre wear particles increased.</p>
<h2>Should we be concerned?</h2>
<p>Concentrations of tyre wear particles as high as 5% are unlikely in the natural environment. But our results are still worrying, particularly as the time in which the animals were exposed to the particles was short. The observed decrease in bivalve feeding and burrowing at low concentrations suggests exposure to tyre wear microplastics in the wild will significantly impact this species.</p>
<p>Any decline in the health of these species could have a knock on effect on the wider marine ecosystem. Burrowing animals, like the bivalve, play crucial roles in recycling nutrients and enhancing photosynthesis. They are also an important food source for larger animals including birds, fish and crabs. </p>
<p>There is evidence that some of the chemicals that leach from these particles are toxic to marine animals. Research shows that they can reduce <a href="https://www.sciencedirect.com/science/article/pii/S0166445X22002259#:%7E:text=Abstract,be%20potentially%20toxic%20to%20biota.">phytoplankton growth</a> and harm the health of <a href="https://www.sciencedirect.com/science/article/pii/S0166445X22002259#:%7E:text=Abstract,be%20potentially%20toxic%20to%20biota.">mussels</a>.</p>
<figure class="align-center ">
<img alt="A glaucous-winged gull holding a large clam in its beak." src="https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527241/original/file-20230519-29-in874j.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">Bivalves are a food source for many larger animals.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/glaucouswinged-gull-holds-large-clam-beak-1911228703">Daniel Bruce Lacy/Shutterstock</a></span>
</figcaption>
</figure>
<p>The chemical make-up of tyres varies depending on brand and car model – subsequently, toxicity will <a href="https://www.emissionsanalytics.com/news/whats-in-a-tyre">vary too</a>. In the future, the complex mixture of components that go into the production of tyres must be risk assessed more rigorously. </p>
<p>The chemicals that are found to have a negative impact on human and environmental health should then be <a href="https://www.sciencedirect.com/science/article/pii/S0269749122011885#:%7E:text=If%20there%20are%20chemicals%20present,be%20provided%20to%20the%20customer.">substituted or removed</a>, thereby reducing the impact of these microplastics in the environment.</p>
<p>Until then, there are several simple things you can do to help. These include maintaining the correct tyre pressure, avoiding sharp braking or acceleration and reducing your vehicle load. All of these will <a href="https://www.actu-environnement.com/media/pdf/news-36643-rapport-ocde-emissions-hors-echappement.pdf">reduce the amount of microplastics</a> that your car releases into the environment.</p><img src="https://counter.theconversation.com/content/205612/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Garrard received her funding through a Daphne Jackson Fellowship, supported by the Natural Environment Research Council (NERC), in association with Plymouth Marine Laboratory and the University of Plymouth.</span></em></p>Inflating your cars’ tyres properly isn’t just good for your bank account - it can minimise your environmental footprint too.Samantha Garrard, Marine Ecosystem Services Researcher, Plymouth Marine LaboratoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2039592023-04-18T15:38:49Z2023-04-18T15:38:49ZHow to be sushi smart: tips on avoiding anisakis disease<figure><img src="https://images.theconversation.com/files/521270/original/file-20230417-16-akyh66.jpg?ixlib=rb-1.1.0&rect=0%2C25%2C1756%2C1014&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nematode larvae belonging to the genus _Anisakis_ can cause the disease anisakiasis, a threat to human health.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-photo/living-anisakis-worm-just-found-on-1142197133">Shutterstock / WH_Pics</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>From sushi and sashimi (Japan) to poke bowls (Hawaii) and ceviche (Peru), consumption of raw or undercooked fish and other seafood is becoming increasingly popular. Appealing as such dishes can be, they can also increase the risk of exposure to fish-borne parasites. </p>
<p>It’s not a matter to take lightly. Every year, almost one in ten people fall ill from eating contaminated food. The World Health Organisation estimates that some <a href="https://www.sciencedirect.com/science/article/pii/S0020751905002766">56 million cases</a> of parasitic infections associated with the consumption of fish products occur annually.</p>
<h2>Tiny but troublesome stowaways</h2>
<p>Among the fish-borne parasites that can affect humans, there are three major groups of parasitic worms, also known as <em>helminths</em>: flatworms, spiny-headed worms (acanthocephalans) and ciliated worms (nematodes).</p>
<p>Diagnoses of infection with Opisthorchis, a family of flatworms, are the most common, but they occur mainly in <a href="https://pubmed.ncbi.nlm.nih.gov/33158552/">East and Southeast Asia</a>. Of more global concern are those caused by some nematodes of the family Anisakidae, particularly species of the genera <em>Anisakis</em>, <em>Pseudoterranova</em> and <em>Contracaecum</em>. As a consequence, they’re the focus of much of the world’s medical and economic concern.</p>
<p>The parasitic disease <a href="https://www.cdc.gov/parasites/anisakiasis/index.html">anisakiasis</a>, caused by nematode larvae belonging to the genus <em>Anisakis</em>, is considered the main threat to human health. Every year and on all continents, countless cases are diagnosed in humans, in part because the rise in consumption of foods such as sushi and sashimi. In Japan alone, where it is traditional to eat raw fish and seafood dishes, more than <a href="https://pubmed.ncbi.nlm.nih.gov/33025215/">7,000 cases of anisakiasis occur annually</a>.</p>
<h2>From marine mammals to human stomachs</h2>
<p>Today, anisakiasis is not only an emerging global human health problem, but it is also an economic concern, due to the potential negative effects on consumer confidence and trade associated with infected fish products.</p>
<p>So how can this troublesome disease be avoided? The answer lies in understanding the parasites’ life cycle.</p>
<p>The genus <em>Anisakis</em> comprises nine species, three of which (<em>Anisakis simplex</em>, <em>Anisakis pegreffii</em> and <em>Anisakis physeteris</em>) have been confirmed as zoonotic pathogens. These nematodes infect a wide range of marine organisms; fish and cephalopods serve as intermediate hosts, while dolphins, whales, seals and other marine mammals are the <a href="https://www.nature.com/articles/s41598-022-17710-1">final hosts</a>.</p>
<p>Adult worms are found in the mucous membrane that lines the stomachs of marine mammals. The parasite’s eggs are expelled along with the animal’s faeces and hatch in seawater. There, krill – small crustaceans that form the basis of the ocean food chain – eat them and become infected with larval stages of the nematodes. When the krill are in turn eaten by fish or squid, another stage of larvae infects the predators’ guts and become embedded on the surface of their organs and eventually in their muscles.</p>
<p>And that’s where we humans come in. When we consume fish, squid, octopus or other seafood containing <a href="https://www.cdc.gov/parasites/anisakiasis/biology.html">third-stage <em>Anisakis</em> larvae</a> that’s raw or undercooked, we can become accidental hosts to <em>Anisakis</em> larvae. Once ingested, they settle in our stomach and sometimes the small intestine.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518175/original/file-20230329-14-yedtuz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-photo/parasites-under-microscope-woman-suffering-helminthiasis-2223896623">New Africa/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Stomach pain and worse</h2>
<p>While the parasite cannot reproduce in humans, it can survive for a short period of time and cause anisakiasis, which can range from mild to severe depending on the person infected. The most typical symptoms of gastric anisakiasis include abdominal pain, nausea and vomiting within hours of ingesting the larvae. Other symptoms can include <a href="https://pubmed.ncbi.nlm.nih.gov/25039016/">allergic reactions</a> and even <a href="https://www.mayoclinic.org/diseases-conditions/anaphylaxis/symptoms-causes/syc-20351468">anaphylactic shock</a>. Infection of the small intestine is less common, but when it occurs it can result in an inflammatory mass and symptoms similar to <a href="https://www.niddk.nih.gov/health-information/digestive-diseases/crohns-disease">Crohn’s disease</a>, which develops one to two weeks later.</p>
<p>Some workers in the fishing industry as well as cooks and other professionals who regularly deal with fish may suffer from occupational allergic anisakiasis. Here, ingestion of the parasite’s larvae is not necessary for the disease to occur – those affected become <a href="https://pubmed.ncbi.nlm.nih.gov/28429304/">sensitive to <em>Anisakis</em> proteins</a> that come into contact with the skin or respiratory tract.</p>
<p>Thankfully, the overall prognosis for anisakiasis is generally positive. Most infections are self-limiting and usually resolve spontaneously after several weeks. Person-to-person transmission is effectively impossible.</p>
<h2>Ceviche, sashimi and even pickled anchovies</h2>
<p>More than 90% of anisakiasis cases worldwide are reported in Japan, and most of the remaining 10% in countries such as Spain, Italy, the United States (Hawaii), the Netherlands and Germany. These are regions where we traditionally eat raw or undercooked fish dishes such as sushi and sashimi, ceviche and carpaccio, <a href="https://www.sciencedirect.com/science/article/pii/S0034528823000607">pickled or pickled anchovies</a>, Hawaiian-style <a href="https://en.wikipedia.org/wiki/Lomi-lomi_salmon">salmon lomi-lomi</a> and salted herring. The species that are <a href="https://www.sciencedirect.com/science/article/pii/S0078323422000446">most frequently parasitised</a> include salmon, tuna, squid, cod, hake, mackerel, mackerel, horse mackerel, blue whiting, sardines and anchovies.</p>
<p>How can anisakiasis be prevented? Preventive measures are essential to control and minimise the disease. While the worms can resist pickling and smoking, semi-preserves such as anchovies and traditionally salted dried fish such as cod or mojamas involve processes that kill the parasite. The best approach is to use a traditional cooking technique such as cooking, frying, baking or grilling. The <a href="https://www.aesan.gob.es/AECOSAN/web/seguridad_alimentaria/subdetalle/anisakis.htm">Spanish Agency for Food Safety and Nutrition</a> reports that when the cooking temperature of a seafood reaches or exceeds 60°C (140 Fahrenheit) for at least one minute, the parasite is killed.</p>
<p>While such methods aren’t an option for fans of sushi, sashimi, and ceviche, freezing is. When seafood is subjected to -20°C for seven days or -35°C for more than 15 hours, the <a href="https://pubmed.ncbi.nlm.nih.gov/32247867/">larvae are destroyed</a>. If you’re not sure that your freezer can go that low, it’s prudent to buy frozen fish. Indeed, to increase consumer food safety, in some countries, commercially prepared sushi is frozen before being sold.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=150&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=150&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=150&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=189&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=189&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521606/original/file-20230418-24-ei0c1n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=189&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Left: A coiled anisakid worm (<em>Pseudoterranova decipiens</em>) in a fillet of cod. Center: The head end of <em>Pseudoterranova decipiens</em>. Right: A <em>Pseudoterranova decipiens</em> recovered from a human patient.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/parasites/anisakiasis/index.html">DPDx/CDC</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><a href="https://food.ec.europa.eu/system/files/2016-10/biosafety_fh_eu_food_establishments-20111214_scfcah_guidance_parasites_en.pdf">European legislation</a> requires that seafood not be offered for sale with visible parasites. To avoid anisakiasis, it’s advisable to buy clean and gutted fish and to visually inspect them – even fish fillets merit examination. </p>
<p>There are a few exceptions from the freezing requirement. Oysters, mussels, clams, and other molluscs; fish from inland waters (rivers, lakes, marshes…) and freshwater fish farms (trout and carp, for example). Farm-raised fish may also be safe, providing that they were reared from embryos obtained in captivity, fed with feed without zoonotic parasites, and kept in a parasite-free environment.</p>
<p>While there’s much to be aware of, it’s better than suffering the consequences of inattention or inaction. With the correct steps and a measure of precaution, it’s possible to enjoy seafood in a safe and responsible way.</p><img src="https://counter.theconversation.com/content/203959/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Raúl Rivas González ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>Raw seafood dishes such as sushi, poke bowls and ceviche are increasingly popular, but can harbour fish-borne parasites. What’s the best way to protect ourselves?Raúl Rivas González, Miembro de la Sociedad Española de Microbiología. Catedrático de Microbiología, Universidad de SalamancaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2019852023-03-24T12:05:51Z2023-03-24T12:05:51ZPlastic fibres stunt growth in mussels by more than a third – here’s why this is a concern<figure><img src="https://images.theconversation.com/files/516996/original/file-20230322-921-v53f75.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3494%2C2321&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tiny pieces of plastic litter have a harmful impact on marine animals, including mussels.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mussels-on-rocks-229688521">Popova Tetiana/Shutterstock</a></span></figcaption></figure><p>Plastic pollution poses a threat to marine wildlife. The plastic bags, bottles and straws that we see strewn across beaches have long been identified as a danger. But tiny fragments of plastic – called microplastics – that are less than 5mm in size are also a major source. </p>
<p>Microfibres are the most common type of microplastic and account for <a href="https://www.sciencedirect.com/science/article/pii/S0269749117349400?via%3Dihub">up to 91%</a> of the microplastics that float around our seas. These minuscule fibres are <a href="https://www.sciencedirect.com/science/article/pii/S0025326X16307639?via%3Dihub">shed from textiles</a> as a result of the wearing and washing of clothes, and from the weathering and abrasion of marine equipment.</p>
<p>Marine animals will encounter and even consume these microplastics. Shellfish, which feed by filtering organic particles from the water, are particularly vulnerable. <a href="https://www.sciencedirect.com/science/article/pii/S0147651319313971">One study</a> found that shellfish ingest far higher concentrations of microplastics than most other marine animals.</p>
<p>At the Plymouth Marine Laboratory, my colleagues and I <a href="https://microplastics.springeropen.com/articles/10.1186/s43591-023-00052-8">studied</a> the effect of microfibre exposure on young blue mussels (only 1cm in length) over three months. Younger animals are generally more vulnerable than adults to changes in their environment. Younger mussels, for example, have <a href="https://academic.oup.com/icesjms/article/37/1/16/622175">higher mortality rates in the wild</a>, mainly due to predation. Therefore, the impact of microplastic contamination on younger mussels is likely to be profound.</p>
<p>We found that prolonged exposure to polyester microfibres led to smaller mussels that grew at a slower rate.</p>
<p>Blue mussels are an important indicator species for scientists as they reveal wider trends in the ecosystem. By constantly filtering water, blue mussels are exposed to pollutants, so are a good indicator of water quality. Mussels, as part of a group of shellfish called bivalves, are also an important part of marine food security. So, if reduced growth is also happening in the wild, it could send shockwaves through the marine ecosystem and the bivalve aquaculture industry.</p>
<h2>Smaller mussels</h2>
<p>In a controlled-temperature laboratory, we exposed the mussels to polyester microfibres (between 0.01mm and 0.5mm in size) at two concentrations: 8 and 80 microfibres per litre. We also exposed mussels to cotton microfibres at 80 microfibres per litre.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A group of mussels caught in a tangle of fishing line." src="https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516938/original/file-20230322-1047-h9fj4o.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">Spot the plastic: a group of mussels caught in a tangle of fishing line. Cornwall, UK.</span>
<span class="attribution"><span class="source">Chris Walkinshaw</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Scientists have found marine microplastic concentrations of <a href="https://www.sciencedirect.com/science/article/pii/S0269749117349400?via%3Dihub">10 particles per litre of seawater</a> to be common. So, the concentrations used by our study are representative of natural environments.</p>
<p>The blue mussels that were exposed to the higher concentration of polyester microfibres were significantly smaller and showed a 36% lower growth rate on average than mussels that were not exposed to any microfibres. This result was only observed in the mussels exposed to the highest concentration of polyester microfibres. Exposure to cotton microfibres did not cause a significant decline in the growth rate of young mussels. </p>
<h2>Spending energy wisely</h2>
<p>Toxicity studies have shown that microplastics can cause damage at the <a href="https://www.frontiersin.org/articles/10.3389/fenvs.2019.00033/full">molecular</a> and cellular level in adult mussels. <a href="https://pubs.acs.org/doi/10.1021/es302332w">One study</a> recorded a strong inflammatory response in mussel cells after six hours of exposure to polyethylene microplastic particles.</p>
<p>The reduction in mussel growth in response to plastic microfibre exposure could stem from a shift in their energetic budget (the balance between the energy taken in and the energy used). These changes could be caused by the mussels altering their feeding behaviours to avoid consuming microfibres, diverting energy away from growth into processing ingested microfibres, or towards repairing the damage caused by these microfibres.</p>
<p>Reduced growth rates in mussels could in turn affect the wider ecosystem. </p>
<p>Young mussels grow at a rapid rate – reaching marketable size in 12 to 24 months. However, they must compete for food and space both with each other and with other species. Younger mussels that cannot grow as fast may be outcompeted by other species and are subject to higher predation. </p>
<p>Smaller mussels are also of less nutritional value. Predators, like crabs, <a href="https://www.britannica.com/animal/whelk">whelks</a>, <a href="https://www.britannica.com/animal/sea-star">starfish</a> and many bird species, may find themselves having to eat more of these smaller mussels. This could impact the populations of both the mussels and their predators.</p>
<p>Humans, as consumers of seafood, will also be affected by smaller mussels. Oysters, mussels and scallops alone provide <a href="https://www.fao.org/publications/sofia/2022/en/">over 8 million tonnes of food</a> to the global population each year. But lower growth rates mean that mussels will take longer to grow to a harvestable size. Smaller animals and longer time-to-market may reduce the profitability of bivalve aquaculture in the future. </p>
<figure class="align-center ">
<img alt="Farmed mussels in the hands of a fisherman." src="https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516945/original/file-20230322-1047-g3fmhm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mussels are an important part of marine food security.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/small-sea-mussels-hands-local-fisherman-1486704878">pang_oasis/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Polluted waters</h2>
<p>Microplastics have a clear impact on the growth of young blue mussels. But the actual impact could be even more severe. </p>
<p>In some more polluted marine environments, scientists have identified microplastic concentrations of up to <a href="https://link.springer.com/article/10.1007/s00244-015-0209-9">182 particles per litre</a> – over double the concentration used in our experiment. <a href="https://www.sciencedirect.com/science/article/pii/S0269749120310253?via%3Dihub#sec3">Separate research</a> also suggests that microplastic concentrations in our oceans may be even higher than currently found, as many particles are too small to capture and count.</p>
<p>Our study highlights the importance of conducting long-term experiments when evaluating the impact of microplastics on marine life. The impact on the cells and tissues of an organism when exposed to microplastics can become evident over short timescales. </p>
<p>But the impact of environmentally relevant concentrations of microplastics on growth, reproduction and survival, which have the greatest relevance to entire populations, require far longer observation periods.</p>
<p>Marine environments are already threatened by overfishing and climate change. Studies like ours are now starting to shed light on the damaging effects of microfibres and other microplastics on the animals within our oceans.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<p class="fine-print"><em><span>Chris Walkinshaw received his PhD funding from the Natural Environment Research Council (NERC), in association with the University of East Anglia in partnership with Plymouth Marine Laboratory.</span></em></p>A study shows that exposure to polyester microfibres inhibits growth in mussels.Chris Walkinshaw, PhD Candidate, Plymouth Marine LaboratoryLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1964702023-02-07T13:34:48Z2023-02-07T13:34:48ZHurricane Harvey more than doubled the acidity of Texas’ Galveston Bay, threatening oyster reefs<figure><img src="https://images.theconversation.com/files/507440/original/file-20230131-4643-5mjeyj.jpg?ixlib=rb-1.1.0&rect=48%2C0%2C5400%2C3564&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Seabirds forage on an oyster shell island on the Texas Gulf Coast.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/an-american-oystercatcher-haematopus-palliatus-foraging-on-news-photo/1449679985">Jon G. Fuller/VW Pics/ Universal Images Group via Getty Images</a></span></figcaption></figure><p>Most people associate hurricanes with high winds, intense rain and rapid flooding on land. But these storms can also change the chemistry of coastal waters. Such shifts are less visible than damage on land, but they can have dire consequences for marine life and coastal ocean ecosystems. </p>
<p>We are oceanographers who study the <a href="https://scholar.google.com/citations?user=u7D6sQgAAAAJ&hl=en">effects of ocean acidification</a>, including on <a href="https://scholar.google.com/citations?user=MOYxO9MAAAAJ&hl=en">organisms like oysters and corals</a>. In a <a href="https://doi.org/10.1038/s43247-022-00608-1">recent study</a>, we examined how stormwater runoff from Hurricane Harvey in 2017 affected the water chemistry of Galveston Bay and the health of the bay’s oyster reefs. We wanted to understand how extreme rainfall and runoff from hurricanes influenced acidification of bay waters, and how long these changes could last. </p>
<p>Our findings were startling. Hurricane Harvey, which generated massive rainfall in the Houston metropolitan area, delivered a huge pulse of fresh water into Galveston Bay. As a result, the bay was two to four times more acidic than normal for at least three weeks after the storm.</p>
<p>This made bay water corrosive enough to damage oyster shells in the estuary. Because oyster growth and recovery rely on many factors, it is hard to tie specific changes to acidification. However, increased acidification certainly would have made it harder for oyster reefs damaged by Hurricane Harvey to recover. And while our study focused on Galveston Bay, we suspect that similar processes may be occurring in other coastal areas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Satellite photo of Houston and the gulf coast immediately after Harvey." src="https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507436/original/file-20230131-5037-8ovozq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This satellite image, taken six days after Harvey made landfall, shows Galveston Bay and other rivers and bays around Houston filled with brown sediment-laden floodwaters.</span>
<span class="attribution"><a class="source" href="https://earthobservatory.nasa.gov/images/90866/texas-waters-run-brown-after-harvey">NASA Earth Observatory</a></span>
</figcaption>
</figure>
<h2>Vast quantities of water</h2>
<p>Scientists predict that climate change will make hurricanes stronger and <a href="https://climate.nasa.gov/news/3184/a-force-of-nature-hurricanes-in-a-changing-climate/">increase the amount of rain they produce</a> over the next several decades. Changes in ocean chemistry, caused by runoff from these storms, are becoming an increasing threat to many marine ecosystems, especially coastal reefs built by oysters and corals. </p>
<p><a href="https://oceanservice.noaa.gov/facts/estuary.html">Coastal estuaries</a> like Galveston Bay, where rivers meet the sea, are some of the most productive ecosystems in the world. Galveston Bay is the largest bay on the Texas coast and one of the largest in the U.S.; it covers about 600 square miles, roughly half the size of Rhode Island. Its extensive oyster reefs provide <a href="https://doi.org/10.1016/j.scitotenv.2021.145132">about 9% of the national oyster harvest</a>. </p>
<p><a href="https://www.climate.gov/news-features/event-tracker/reviewing-hurricane-harveys-catastrophic-rain-and-flooding">Hurricane Harvey</a>, the wettest tropical cyclone in U.S. history, made landfall on the Texas coast as a Category 4 hurricane on Aug. 26, 2017. Harvey stalled at the coast for four days, sitting over both land and ocean. </p>
<p>Maintaining contact with warm Gulf of Mexico waters fueled the storm with both energy and rainfall, allowing it to persist and drop extreme amounts of rain directly onto Houston and surrounding areas – <a href="https://theconversation.com/what-made-the-rain-in-hurricane-harvey-so-extreme-83137">up to 50 inches in four days</a>. All of that rain and floodwater had to go somewhere, and much of it flowed into Galveston Bay. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YzQGgyrxXiI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">These videos show the scale of flooding across Houston from Hurricane Harvey.</span></figcaption>
</figure>
<h2>Climate change and ocean acidification</h2>
<p>The ocean acidification issues that we study are a <a href="https://theconversation.com/global-warmings-evil-twin-ocean-acidification-19017">well-known effect related to climate change</a>. Human activities, mainly burning fossil fuel, emit carbon dioxide into the atmosphere. The ocean absorbs about one-third of these emissions, which alters ocean chemistry, making seawater more acidic. </p>
<p>Acidification can <a href="https://www.epa.gov/ocean-acidification/effects-ocean-and-coastal-acidification-marine-life">harm many forms of marine life</a>. It is especially dangerous for animals that build their shells and skeletons out of calcium carbonate, such as oysters and corals. As seawater becomes more acidic, it makes these structures harder to build and easier to erode. </p>
<p>Oysters fuse together as they grow, creating large rocklike underwater reefs that <a href="https://www.youtube.com/watch?v=PbFQ5EndLso">protect shorelines from wave erosion</a>. These reefs <a href="https://www.fisheries.noaa.gov/national/habitat-conservation/oyster-reef-habitat">provide habitat</a> for other creatures, such as barnacles, anemones and mussels, which in turn serve as food sources for many fish species. </p>
<p>Rising atmospheric CO₂ levels are acidifying oceans worldwide. As our study shows, local events like tropical cyclones can add to global acidification. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"661924520496922624"}"></div></p>
<h2>Stormwater from Harvey caused extreme coastal acidification</h2>
<p>The main cause of the unprecedented acidification that occurred after Hurricane Harvey was the excessive amount of rainfall and runoff that entered Galveston Bay. To help manage large-scale flooding in the Houston area, the city released large volumes of water from reservoirs for more than two months after Harvey. These releases extended the time during which stormwater entered Galveston Bay and increased its acidity. </p>
<p>Scientists use the pH scale to measure how acidic or basic (alkaline) water is. A pH value of 7 is neutral; higher values are basic, and lower values are acidic. The pH scale is logarithmic, so a decrease of one full unit – say, from 8 to 7 – represents a tenfold increase in acidity. </p>
<p>Rainwater is more acidic than either river water or seawater, which pick up minerals from soil that are slightly basic and can balance out absorbed carbon dioxide from the atmosphere. Rainwater’s pH is around 5.6, compared with <a href="https://datastream.org/en/guide/ph">between 6.5 and 8.2 for rivers</a> and <a href="https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification">about 8.1 for seawater</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Th pH scale with values for common substances." src="https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=240&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=240&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=240&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=302&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=302&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508452/original/file-20230206-25-fdap84.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=302&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 pH scale shows how acidic or basic substances are.</span>
<span class="attribution"><a class="source" href="https://www.epa.gov/acidrain/what-acid-rain">USEPA</a></span>
</figcaption>
</figure>
<p>Galveston Bay contains a mix of fresh water from rivers and salty seawater from the Gulf of Mexico – oysters’ preferred habitat. We collected water samples in the bay two weeks after Harvey and found that the bay was made up almost entirely of river water and rainwater from the storm. </p>
<p>Since rainwater, river water and seawater all have different chemistries, we were able to calculate that rainwater made up almost 50% of the water in the bay. This means that acidic rainwater from Harvey replaced the basic seawater within the bay after the storm. The average bay water pH had dropped from 8 to 7.6, a 2.5-fold increase in acidity. Some zones had pH even as low as 7.4 – four times more acidic than normal. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bar charts showing combinations of seawater, river water and rainwater in Galveston Bay before and after Hurricane Harvey." src="https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=466&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=466&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=466&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507432/original/file-20230131-24-p6tcnw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These charts show how rainfall and runoff from Hurricane Harvey altered the composition of Galveston Bay after the storm made landfall on August 25, 2017.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s43247-022-00608-1">Tacey Hicks, modified from Hicks et al., 2022</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This extreme acidification lasted for more than three weeks. Bay waters became corrosive not only to more sensitive larval and juvenile oyster shells, but to adult oyster shells as well. <a href="https://doi.org/10.1002/jgrc.20378">Scientists had predicted</a> that increasing CO₂ could cause this scale of coastal acidification but did not expect to see it until around the year 2100. </p>
<p>The fresh water from Harvey also caused a <a href="https://doi.org/10.1016/j.scitotenv.2021.145132">severe oyster die-off</a> in the bay because oysters need slightly salty water to survive. Harvey struck in the middle of oyster spawning season, and acidification may have slowed reef recovery by making it harder for young oysters to form new shells. Officials at the <a href="https://tpwd.texas.gov/">Texas Parks and Wildlife Department</a> have told us that four years later, in late 2021, some Galveston Bay oyster reefs still showed <a href="https://doi.org/10.1038/s43247-022-00608-1">very low additions of new oysters</a>. </p>
<h2>Other coastal areas at risk</h2>
<p>Only a few studies, including ours, have analyzed how tropical cyclones affect coastal acidification. In our view, however, it is highly possible that other storms have caused the kind of extreme acidification that we detected in the wake of Harvey. </p>
<p>We reviewed the 10 wettest <a href="https://www.wpc.ncep.noaa.gov/tropical/rain/tcmaxima.html">tropical cyclones in the U.S. since 1900</a> and found that nine, including Harvey, caused large amounts of rain and flooding in coastal areas with bay or estuary ecosystems. Other storms didn’t produce as much rainfall as Harvey, but some of the affected bays were much smaller than Galveston Bay, so less rain would have been needed to replace seawater in the bay and cause a similar level of acidification to what Harvey produced.</p>
<p>We think that this likely has already occurred in other places struck by hurricanes but went unrecorded because scientists weren’t able to measure acidification before and after the storms. As climate change continues to make tropical cyclones larger and wetter, we see storm-induced acidification as a significant threat to coastal ecosystems.</p><img src="https://counter.theconversation.com/content/196470/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tacey Hicks received funding from Texas Sea Grant to support the publication of this study. Tacey Hicks is currently affiliated with the National Oceanic and Atmospheric Administration and Texas Sea Grant as part of the John A Knauss Marine Policy Fellowship. </span></em></p><p class="fine-print"><em><span>Kathryn Shamberger receives funding from the National Science Foundation, US Department of Energy, and US Environmental Protection Agency.</span></em></p>Climate change is making oceans more acidic globally. Now, scientists are finding that large storms can send pulses of acidic water into bays and estuaries, further stressing fish and shellfish.Tacey Hicks, PhD Candidate in Oceanography, Texas A&M UniversityKathryn Shamberger, Associate Professor of Oceanography, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1922742022-11-09T14:12:58Z2022-11-09T14:12:58ZClimate change: West Africa’s oceans at risk because of a lack of monitoring<figure><img src="https://images.theconversation.com/files/492280/original/file-20221028-53244-can6ka.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The West African coastline is a source of livelihood for millions.</span> <span class="attribution"><span class="source">Wikimedia Commons/Paul Walter</span></span></figcaption></figure><p>The <a href="https://www.britannica.com/place/Canary-Current">West African Canary Current</a> extends along the north-west African coast, from the northern Atlantic coast of Morocco to Guinea-Bissau. It’s a hotspot for changes in the oceans driven by climate change. These include rising temperatures, <a href="https://www.nrdc.org/stories/what-you-need-know-about-ocean-acidification">ocean acidification</a> and <a href="https://scripps.ucsd.edu/research/climate-change-resources/faq-ocean-deoxygenation#:%7E:text=Deoxygenation%20is%20the%20overall%20decline,through%20photosynthesis%2C%20ventilation%2C%20mixing.">ocean deoxygenation</a>. All affect marine life on multiple levels. </p>
<p>The current is one of the world’s most productive ocean ecosystems, a consequence of the upwelling of cold and nutrient-rich waters. Ecosystems like this provide around <a href="https://www.sciencedirect.com/science/article/pii/S2590332221004115#:%7E:text=Expanding%20ocean%20observation%20and%20climate%20services%20to%20build%20resilience%20in%20West%20African%20fisheries,-Author%20links%20open&text=The%20Canary%20Current%20is%20a,for%20national%20economies%20and%20livelihoods">20% of global fish catches</a> and support livelihoods in coastal communities. </p>
<p>From 2016 -2019, we worked with an international team to draw attention to the impacts of climate change on the West African Canary Current. In a <a href="https://www.sciencedirect.com/science/article/pii/S2590332221004115#:%7E:text=Expanding%20ocean%20observation%20and%20climate%20services%20to%20build%20resilience%20in%20West%20African%20fisheries,-Author%20links%20open&text=The%20Canary%20Current%20is%20a,for%20national%20economies%20and%20livelihoods.">recent publication</a>, we described the limited economic and institutional capacity to monitor and respond to climate variability and change in the countries bordering the West African Canary Current and the urgent need to build scientific capacity in the region in order address this shortcoming.</p>
<h2>What’s missing</h2>
<p>The waters of the West African Canary Current share a key characteristic with those of the coast of Oregon in the Pacific north west of America – namely ocean acidification. This happens when the large amounts of carbon dioxide being absorbed by the ocean dissolves in seawater as carbonic acid.</p>
<p>In 2007 shellfish growers in Oregon were nearly all wiped out economically due to increasing acidity of the ocean. The waters they grew their shellfish in had become corrosive to calcium carbonate – the building block for the skeletons and shells of shellfish and corals. The waters they farmed in had become corrosive to the shells of the sea butterfly, <em>Limacina helicina</em>, a delicate sea snail that is only 5mm across. The snail underpins key marine food webs that sustain herring, salmon, whales, seals, seabirds and other species. </p>
<p>But in California, people who depend on the ocean for their livelihood are in a position to understand, anticipate and to some degree adapt to the impacts of climate change on the region. This is thanks to an extensive network of state-of-the-art sensors and input from researchers from academia and the US government.</p>
<p>This is not the case in West Africa. There is only a single mooring – these are long anchored lines of scientific equipment and floats which are deployed to collect a range of ocean data over long periods – managed by French researchers to monitor the impacts of climate change on the West African Canary Current. </p>
<p>Communities are effectively left blind to the effects of climate change. So they can’t take informed measures to adapt.</p>
<p>For example, if a fishery or shellfish stock collapses, stakeholders won’t know what the cause is. It could be as a consequence of overharvesting, deoxygenation that causes fish to migrate to more oxygen-rich waters, or shellfish mortality brought on by acid waters. Or a combination of these factors – or others. </p>
<p>Scientists, managers and stakeholders who want to understand and address the management of fisheries in the Canary Current can’t build or use models because there isn’t data. </p>
<p>To be useful, models must take into account the changes, variations and interactions of the ocean in the region. They must also be supported by regional data.</p>
<p>Without this information, results of tests are incomplete at best and misleading at worst. They are thus unsuitable for guiding management, policy, or donor decisions.</p>
<h2>Solutions</h2>
<p>Scientists from Chile have shown how the rigorous monitoring of climate change, and assessing its impacts on local shellfish species, can inform adaptation efforts. Chile borders the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0079661109001049">Humboldt Current System</a>, an Eastern boundary upwelling ecosystem that extends along the west coast of South America. They have discovered shellfish strains that are relatively tolerant to ocean acidification and optimal habitats for their potential cultivation. This provides a potential means of adaptation to future, and likely more acidic, oceans. These findings are <a href="https://www.researchgate.net/publication/287360675_Shellfishing_and_shell_midden_construction_in_the_Saloum_Delta_Senegal">applicable to Senegal</a>, where shellfish have been for at least 5,000 years.</p>
<p>An essential step to building the capacity required to effectively anticipate and adapt to changing ocean chemistry in the Canary Current will the training of additional African Ph.D.-level scientists. This training could be in disciplines such as oceanography, ecology, and physiology. This could be accomplished through novel north-south or south-south partnerships among institutions of higher education or through the strengthening of existing international partnerships. West African scientists would be best suited to address context-specific adaptation measures and incorporate their findings into national policies and legislation. </p>
<p>Another benefit of understanding climate change impacts on West African oceans would be to add more voices to the global chorus calling for reductions in CO2 emissions. Greater representation for those that are most vulnerable, yet least responsible, for those emissions is also important. </p>
<p>Wealthy nations rely upon the data from programmes to monitor ocean acidification, deoxygenation and warming to develop reliable models and policies that provide guidance to industries and local stakeholders. The West African countries bordering the Canary Current, for whom climate change impacts on the oceans will impact livelihoods, food security, and development outcomes, deserve no less.</p><img src="https://counter.theconversation.com/content/192274/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There is only a single mooring managed by French researchers that monitors the impacts of climate change on West African Canary Current.Todd L Capson, Chercheur Associé, Institut de physique du globe de Paris (IPGP)Marie Boye, Research Director, CNRS, Institut de physique du globe de Paris (IPGP)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1822052022-05-16T17:57:40Z2022-05-16T17:57:40ZClimate change is now on the menu at seafood restaurants<figure><img src="https://images.theconversation.com/files/462902/original/file-20220512-22-fd3ssw.jpg?ixlib=rb-1.1.0&rect=30%2C90%2C6679%2C4124&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Warmer-water preferring fish species like sardines and squid may soon dominate seafood menus on the west coast of Canada. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/climate-change-is-now-on-the-menu-at-seafood-restaurants" width="100%" height="400"></iframe>
<p>Restaurant menus across the West Coast of Canada will soon see an influx of squid and sardine dishes, while the popular sockeye salmon makes a slow exit. As it turns out, <a href="https://news.ubc.ca/2022/04/21/vancouver-restaurant-menu-squid-sockeye-salmon/">climate change may have something to do with this</a>.</p>
<p>Restaurants update their menus all the time and this often goes unnoticed by diners. These changes are driven by culinary trends, consumer preferences and many environmental and socio-economic factors that affect the availability of the ingredients. According to <a href="https://doi.org/10.1007/s10641-022-01244-6">a recent study</a> published by my research team, we can now add climate change to this list. </p>
<p>We found that as the ocean temperature rises, many marine fish and shellfish move from their traditional habitats towards the North and South Poles in search of cooler waters. This movement of fish stocks affects the availability of seafood catch, compelling chefs to rewrite the menus of seafood restaurants on the West Coast of Canada.</p>
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Read more:
<a href="https://theconversation.com/species-on-the-move-4-ways-conservation-can-adapt-in-an-era-of-climate-change-179254">Species on the move: 4 ways conservation can adapt in an era of climate change</a>
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<h2>Climate change affects our ocean and fisheries</h2>
<p>The latest report from the UN’s <a href="https://www.ipcc.ch/report/ar6/wg2/">Intergovernmental Panel on Climate Change</a> confirmed that climate change is impacting the ocean, fish stocks and fisheries through ocean warming, loss of sea ice, <a href="https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification">ocean acidification</a>, heatwaves, <a href="https://www.iucn.org/theme/marine-and-polar/our-work/climate-change-and-oceans/ocean-deoxygenation">ocean deoxygenation</a> and other <a href="https://www.ipcc.ch/srocc/">extreme weather events</a>.</p>
<figure class="align-center ">
<img alt="Underwater bleached white corals surrounded by fish." src="https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463076/original/file-20220513-24-cnheuf.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">Fish stocks are affected by ocean warming, acidification, loss of sea ice and many other effects of climate change.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The impacts of warming-induced ecological shifts are also seen in our fisheries. Fish catches around the world are increasingly dominated by <a href="https://doi.org/10.1038/nature12156">species that prefer warmer water</a>.</p>
<p>We applied an index called “mean temperature of catch” to measure such changes in species of fish caught along the West Coast of Canada, and found that the catch of warmer-water species in this region has increased from 1961 to 2016. </p>
<h2>Relating seafood on menus to climate change</h2>
<p>But how exactly do these changes in fisheries catch dictate the food that appears in our plates? <a href="https://news.ubc.ca/tag/john-paul-ng/">My co-author John-Paul Ng</a> and I decided to tackle this question ourselves by focusing our efforts on the West Coast of Canada and the U.S. where many restaurants serve seafood.</p>
<p>We looked at present-day menus from restaurants in these areas, along with menus — some dating back to the 19th century — taken from historical archives in city halls and local museums. </p>
<figure class="align-center ">
<img alt="A restaurant menu from 1888" src="https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463081/original/file-20220514-21-ipvlc5.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">Caption Hotel Vancouver 1888 dinner menu. Restaurant menus show the seafood selection at different periods in time.</span>
<span class="attribution"><span class="source">(City of Vancouver Archives, AM1519-PAM 1888-17)</span></span>
</figcaption>
</figure>
<p>After looking at 362 menus, we used a similar approach to the one we developed to study fisheries catches and calculated a “<a href="https://doi.org/10.1007/s10641-022-01244-6">mean temperature of restaurant seafood</a>.” This index represents the average preferred temperature across all seafood species that appeared on the sampled menus from restaurants in a city for a specific time period. This index is a tool to help us gauge whether our restaurants are serving more or less warm and cold water seafood. </p>
<p>We found that the average preferred water temperature of fish and shellfish appeared in our menu increased to 14 C in recent times (2019-21) from 9 C in 1961-90 period. </p>
<p>This increase in the preferred water temperature of fish on restaurant menus is connected to changes in sea water temperature and the temperature-related changes in the composition of fish species caught during the same time period.</p>
<h2>More squid and sardine dishes</h2>
<p>Ocean warming is starting to change the variety of seafood available. </p>
<p>Driven by the higher ocean temperature in the northeast Pacific Ocean, <a href="https://doi.org/10.1073/pnas.0702043104">the Humboldt squid — a large, predatory squid species</a> that inhabits the eastern Pacific Ocean — is now making more frequent appearances on present-day restaurant menus in Vancouver.</p>
<p>British Columbia once had a commercially important Pacific sardine fishery, which was a common restaurant seafood. After the fishery collapsed in the <a href="https://doi.org/10.1139/f94-048">mid-1940s</a>, the fish seldom appeared in our sampled restaurant menus.</p>
<figure class="align-center ">
<img alt="A school of fish in the ocean water." src="https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463080/original/file-20220514-26-1fd1kh.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">Research shows that sardines will soon become more abundant in B.C. waters.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>According to research conducted by colleagues in <a href="https://doi.org/10.1371/journal.pone.0196127">fisheries research</a> and <a href="https://doi.org/10.1371/journal.pone.0145285">by our team at the Institute for the Oceans and Fisheries</a>, the sardines, which prefer warmer water, will soon make a big comeback on the West Coast of Canada. We expect that more sardine dishes will start appearing on the menus of restaurants here.</p>
<h2>Responding to changing seafood availability</h2>
<p>Globalization and the diversification of cuisines have brought a wider array of seafood options to coastal cities such as Vancouver and Los Angeles. Imported and farmed <a href="https://doi.org/10.1016/j.jcomm.2017.12.004">seafood are increasingly common ingredients in menus</a>.</p>
<p>As climate change continues to shuffle species’ distribution in ocean waters, we expect that climate-induced changes to seafood menus at restaurants will become even more pronounced. </p>
<p>Our study on restaurant menus underscores the <a href="https://www.downtoearth.org.in/news/climate-change/climate-crisis-may-destroy-aquatic-food-systems-and-livelihoods-economies-79066">wide-ranging impacts of climate change on our food system</a>. In cases where alternative seafood ingredients are available and consumer preferences are flexible, the impacts on our social, economic and cultural well-being may be limited. However, substantial <a href="https://www.vancity.com/viewport/mobile/SharedContent/documents/pdfs/News/Vancity-Report-Impact-of-Climate-Change-on-Seafood-in-BC-2015.pdf">negative consequences</a> are likely to be felt by many vulnerable communities that do not have the capacity to adapt to such changes. </p>
<p>Global and local actions to support both climate change adaptation and mitigation are essential if we want the ocean to continue to provide food for the people around the world who rely on it for nutritional security.</p><img src="https://counter.theconversation.com/content/182205/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William W. L. Cheung receives funding from NSERC, SSHRC, CIHR, and the David and Lucile Packard Foundation.</span></em></p>As the ocean temperature rises, many marine species are moving toward the north and south poles in search of cooler waters, thus rewriting the menus of seafood restaurants on the West Coast of Canada.William W. L. Cheung, Professor and Director, Institute for the Oceans and Fisheries, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1643302022-01-19T05:52:03Z2022-01-19T05:52:03ZLeaf oysters: the unsung heroes of estuaries are disappearing, and we know almost nothing about them<figure><img src="https://images.theconversation.com/files/441435/original/file-20220119-23-ibcqig.jpg?ixlib=rb-1.1.0&rect=11%2C23%2C3982%2C2970&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Charlotte Jenkins </span>, <span class="license">Author provided</span></span></figcaption></figure><p><em><strong><a href="https://theconversation.com/au/topics/am-i-not-pretty-enough-106740">Am I not pretty enough?</a></strong> This article is part of The Conversation’s series introducing you to Australia’s unloved animals that need our help.</em></p>
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<p>Camouflaged by a layer of silty mud, most people probably wouldn’t notice the large flat oysters lurking beneath shallow water in Australia’s coastal estuaries. These are remarkable “leaf oysters”, and they can form reefs, produce mauve pearls, and reach the size of a dinner plate.</p>
<p>Of the 14 species of reef-forming oysters and mussels in Australia, leaf oysters (<em>Isognomon ephippium</em>) are the least well known. <a href="https://www.tandfonline.com/doi/full/10.1080/13235818.2020.1837054">Our review</a>, published last year, found only 30 publications globally that mention leaf oysters. Half of those were only incidental recordings.</p>
<p>This is a huge problem because there is <a href="https://academic.oup.com/bioscience/article/61/2/107/242615">widespread evidence</a> of significant declines in the number and condition of shellfish reefs. In Australia, 99% of shellfish reefs have been <a href="https://www.shellfishrestoration.org.au/the-problem/">described as</a> “functionally extinct”, meaning the habitat these reefs previously provided has now been lost. </p>
<p>This has led to serious efforts in shellfish reef <a href="https://www.natureaustralia.org.au/what-we-do/our-priorities/oceans/ocean-stories/oyster-reef-habitat/">restoration</a>. Leaf oysters are crucial members of these ecosystems, and we need substantially more information about them to ensure they’re not left out of these programs. Let’s delve into what we do know.</p>
<h2>Meet the leaf oyster</h2>
<p>Oysters are often associated with <a href="https://theconversation.com/buy-australian-oysters-and-farmed-barramundi-5-tips-to-make-your-feast-of-summer-seafood-sustainable-172954">summer feasts and intensive aquaculture</a>. While leaf oysters are edible, they have a large shell to meat ratio and so aren’t particularly attractive as a source of food for humans. </p>
<p>But like the iconic pearl oysters, leaf oysters are members of the Pteridine family of bivalve molluscs and have an inner nacre layer. This means they can produce pearls mainly mauve in colour, or sometimes purple, bronze, cream or silver.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1006&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1006&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1006&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leaf oysters can be the size of a dinner plate.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Although not much is known about the life history of leaf oysters, we do know they reproduce by spawning. Thousands of eggs and sperm are released into the water and develop into swimming larvae after fertilisation. Only a fraction of these survive and settle onto the substrate, where they develop into juvenile oysters. </p>
<p>Like other reef-forming oysters such as the Sydney rock oyster and the Pacific oyster, leaf oyster larvae appear to be attracted to the shells of the adult oysters. They attach to the surface via “byssus” – a matt of strong hair-like threads. This enables shell clusters to form, which can develop into leaf oyster reefs.</p>
<p>Leaf oysters are ecosystem engineers. When they live in dense clumps, they support an entire ecosystem of fish and other invertebrates. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?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"></a>
<figcaption>
<span class="caption">Leaf oysters are crucial members of shellfish reef ecosystems.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The flat, plate-like shape of the leaf oysters provides a complex three-dimensional habitat, with many nooks and crannies for species to seek shelter from drying out at low tide, and to hide from predators at high tide. Their shells provide a hard surface for other invertebrates to attach to, and form biofilms grazed by snails and fish.</p>
<p>Our preliminary studies on leaf oyster beds have detected a high diversity of fish species. Using underwater videos, we recorded a number of important fishing species, including yellowfin bream, dusky flathead, sand whiting, sand mullet, leatherjacket and black spotted snapper. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=576&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=576&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=576&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A screenshot from our undersea survey videos.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Keeping estuaries clean</h2>
<p>Leaf oyster reefs are found on soft sediment in estuaries, on sand, mud and among mangroves, in tropical and subtropical regions around the world. In Australia, they’re found from Exmouth in Western Australia to the Macleay River on the mid-north coast of New South Wales. </p>
<p>We’ve also seen leaf oysters on artificial rock walls and in shallow water along the edge of small boat harbours. Some of these are likely to be remnant populations of larger clusters or reefs, but given they’re often partially buried, there’s little information available about their past distribution.</p>
<p>Like <a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">other oyster reefs</a>, we expect leaf oysters play a significant role in maintaining water quality and nutrient cycling in estuaries. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">The surprising benefits of oysters (and no, it's not what you're thinking)</a>
</strong>
</em>
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<p>Coastal lakes and estuaries are a major repository of run-off from agriculture and urban development, leading to poor water quality. Shellfish reefs in healthy estuaries can buffer this effect by removing particles and bacteria from the water, and reducing dissolved nutrients and algal blooms.</p>
<p>As animals that eat food suspended in water, leaf oysters can filter vast volumes of water each day. With their large gills and extremely flat shape, their filtration abilities are highly effective in slow-moving tidal waters.</p>
<p>Oyster reefs more generally also trap and stabilise sediment, which can provide an important buffer against coastal erosion.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&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 inside of a leaf oyster.</span>
<span class="attribution"><span class="source">Chamara Benthotage</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Threats to leaf oyster reefs</h2>
<p>The current condition of shellfish reefs in Australia <a href="https://theconversation.com/ah-shucks-how-bushfires-can-harm-and-even-kill-our-delicious-oysters-131294">is dire</a>. Declining water quality is recognised as one of the most serious threats to estuaries, with excessive nutrients leading to algal blooms, which can be harmful.</p>
<p>High amounts of sediment can clog up the gills of filter-feeding oysters and can lead to the complete burial of historical oyster reefs. In the past, dredging for oysters, boat harbours and breakwaters has also directly damaged oyster reefs. </p>
<p>Our recent surveys (which aren’t yet published) of leaf oyster beds across four estuaries in northern NSW suggest leaf oysters have disappeared from some locations where they were previously known to live. In the remaining beds, we found 30-67% of the shells to be dead. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fewer leaf oysters lead to poorer water quality.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Their deaths have terrible knock-on effects and are correlated with poor water quality after rain, high acidity, low dissolved oxygen, high nutrients and higher rates of sedimentation.</p>
<p>But one of biggest threats to leaf oyster populations is the lack of knowledge on the species. In particular, the lack of historical information on where they live and how many there are makes it difficult to document how they’ve declined. And this is necessary for listing them as threatened species. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.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">We need more comprehensive maps of leaf oyster distribution.</span>
<span class="attribution"><span class="source">Chamara Benthotage</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our concern extends beyond the survival and protection of the single species, to the entire ecosystem the leaf oysters underpin. </p>
<p>Improving our understanding of leaf oyster reefs requires more comprehensive mapping of the remaining populations and gaining a better understanding of their life cycle. This includes when they breed, how the larvae develop and where they settle, their age at sexual maturity and how long they live.</p>
<p>This will help us <a href="https://www.marine.nsw.gov.au/knowledge-centre/newsroom/news/leaf-oysters-a-potential-lifeline-in-reef-restoration">include them in reef restoration</a> and estuarine management plans, protecting Australia’s precious, fragile wildlife in the face of a difficult future.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ah-shucks-how-bushfires-can-harm-and-even-kill-our-delicious-oysters-131294">Ah shucks, how bushfires can harm and even kill our delicious oysters</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/164330/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kirsten Benkendorff receives funding from NSW Department of Primary Industries, Fisheries, Coffs Harbour City Council Environmental Levy and the Asia-Pacific Network for Global Change Research.</span></em></p><p class="fine-print"><em><span>Victoria Cole receives funding from the NSW Marine Estate and works for the NSW Department of Primary Industries, Fisheries.</span></em></p><p class="fine-print"><em><span>Chamara Benthotage 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>Leaf oysters can form reefs, produce mauve pearls, and reach the size of a dinner plate. They’ve been ignored for far too long.Kirsten Benkendorff, Associate Professor in Marine Biology, Southern Cross UniversityChamara Benthotage, PhD candidate, Southern Cross UniversityVictoria Cole, Adjuct, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1738712021-12-16T14:42:30Z2021-12-16T14:42:30ZHow the humble limpet helped humans develop, survive and thrive<figure><img src="https://images.theconversation.com/files/437805/original/file-20211215-19-1iyknrw.JPG?ixlib=rb-1.1.0&rect=16%2C0%2C3626%2C2730&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Louise Firth/University of Plymouth</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The humble <a href="https://www.wildlifetrusts.org/wildlife-explorer/marine/sea-snails-and-sea-slugs/limpet">limpet</a> generally doesn’t attract much attention. Most of us remember them from childhood as tenacious little creatures clinging to rocks, impossible to prise off. But this familiar, cone-shaped animal has played an important part in the development of humans across the globe.</p>
<p>As my recent <a href="http://press-files.anu.edu.au/downloads/press/n9154/pdf/01_firth.pdf">research</a> underscored, limpets have long been important to humans as food, cultural symbols, offerings in religious and spiritual rituals, and even currency.</p>
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<h2>From ancient middens to modern cuisine</h2>
<p>Unlike mussels and oysters, limpets are now widely seen as a distinctly unfashionable and underused shellfish, despite containing essential <a href="https://www.fitbit.com/foods/Abalone+Limpet+Shellfish/37930">vitamins and minerals</a>.</p>
<p>But limpets were harvested for food for hundreds of thousands of years by ancestors of modern humans including <a href="https://www.nhm.ac.uk/discover/who-were-the-neanderthals.html">Neanderthals</a>, our closest ancient relatives. And around 100,000 years ago, limpets constituted an important part of the diet of <a href="https://www.history.com/news/prehistoric-ages-timeline">Middle Stone Age</a> people.</p>
<p>In fact, it is generally understood that a <a href="https://www.theguardian.com/uk/2002/may/26/medicalscience.research">switch to a seafood diet</a> – fish and shellfish are rich in omega fatty acids which are <a href="https://www.eatright.org/health/wellness/healthy-aging/brain-health-and-fish">essential for brain health and vitality</a> – led to the evolution of the large, complex brain of <a href="https://humanorigins.si.edu/evidence/human-fossils/species/homo-sapiens"><em>Homo sapiens</em></a> (modern humans).</p>
<p>Indeed, when modern humans first began to migrate, they often followed coastal routes, so they easily could access a year-round <a href="https://www.bushcrafthub.com/common-limpet-foraging/#What_is_the_scientific_name_for_limpets">source of nutritious food</a> – including limpets. </p>
<p>Archaeological investigations into <a href="https://www.thoughtco.com/midden-an-archaeological-garbage-dump-171806">prehistoric middens</a> (rubbish heaps) has revealed that not only were limpets eaten all over the world, they were often the <a href="https://journals.co.za/doi/pdf/10.10520/EJC97636">dominant shellfish</a> in people’s diets. They were known to have been eaten by ancient civilisations, including the Greeks and Romans, and the early Vikings.</p>
<p>More recently, highly profitable commercial operations in Hawaii, California, Mexico, Chile and the Azores have collapsed <a href="https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/illegal-harvesting-affects-the-success-of-fishing-closure-areas/E7C5944A7DF22D8B8945BB341188B3DB">due to over-exploitation</a>. But some species of limpet are now highly-prized and considered delicacies in places like Madeira, the Azores and Hawaii. Known as <em>opihi</em> in Hawaii, the limpet is called the “fish of death” because many people lose their lives harvesting them from rocky locations exposed to pounding waves. </p>
<h2>Sustaining in times of starvation</h2>
<p>Limpets have long been associated with poverty and starvation, and are often referred to as “<a href="https://link.springer.com/article/10.1007/s11457-018-9218-y">famine food</a>” or “poor food”. In Scotland, limpets are symbolic of the <a href="https://scottishhistorysociety.com/the-highland-clearances/">Highland Clearances</a> (1750-1860) when tenant crofters were evicted from their homes by estate landowners to make way for sheep. Most were driven to hunger and destitution.</p>
<p>This symbolism is epitomised by author <a href="https://www.bbc.co.uk/programmes/profiles/2SMhK7YlrfpdsCQVyNpPQ4Q/neil-m-gunn">Neil Gunn</a> who makes myriad references to eating limpets in his books, which describe the harsh lives of rural communities in the northeast of Scotland in the early part of the 20th century.</p>
<p>In Ireland, too, there are many stories about people surviving off seaweed, limpets and other common shellfish during the many famines that hit the country in the 1800s. Before the 19th century, it was mainly the poor that gathered shellfish from the shore. Such fare was referred to as <em>cnuasach mara</em> (sea pickings).</p>
<p>Many people in Ireland still associate limpets with destitution and starvation, often referring to them as <em>bia bocht</em> – “poor food” or “famine food”. This is perhaps best captured by the old Irish saying: <em>Bia rí isea dúilicíní ach bia tuathaigh isea báirnigh</em>, which translates as “mussels are the food of kings, limpets are the food of peasants”.</p>
<figure class="align-center ">
<img alt="A famine-hit Irish family collecting limpets and seaweed on the beach in the 19th century." src="https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437806/original/file-20211215-19-kj03lo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A famine-hit family collecting limpets and seaweed on Inishbofin Island, Donegal, in the 19th century.</span>
<span class="attribution"><a class="source" href="https://www.alamy.com/christian-herald-and-signs-of-our-times-new-york-300-the-christian-herald-and-signs-of-our-times-may-13-mr-sam-small-the-evangelist-a-starving-irish-family-gathering-seaweed-and-limpets-seejage-the-flesh-of-a-heifer-without-counting-a-largequantity-of-bones-for-there-only-remained-a-ribor-two-and-even-many-of-the-marrow-bones-hadbeen-broken-as-if-with-a-hammer-mr-sam-small-see-portrait-on-this-age-unlike-mr-moody-sam-jones-has-chosen-ashis-helper-in-gospel-work-not-a-singer-but-apreacher-sam-small-is-affectionately-spokenof-by-his-leader-as-his-son-timothy-for-image339226977.html?pv=1&stamp=2&imageid=203C2D0B-2B91-4720-A432-EACC420D44D3&p=1221884&n=8&orientation=0&pn=1&searchtype=0&IsFromSearch=1&srch=foo%3Dbar%26st%3D0%26sortby%3D2%26qt%3Dgathering%2520limpets%26qt_raw%3Dgathering%2520limpets%26qn%3D%26lic%3D3%26edrf%3D0%26mr%3D0%26pr%3D0%26aoa%3D1%26creative%3D%26videos%3D%26nu%3D%26ccc%3D%26bespoke%3D%26apalib%3D%26ag%3D0%26hc%3D0%26et%3D0x000000000000000000000%26vp%3D0%26loc%3D0%26ot%3D0%26imgt%3D0%26dtfr%3D%26dtto%3D%26size%3D0xFF%26blackwhite%3D%26cutout%3D%26archive%3D1%26name%3D%26groupid%3D%26pseudoid%3D%26userid%3D%26id%3D%26a%3D%26xstx%3D0%26cbstore%3D1%26resultview%3DsortbyPopular%26lightbox%3D%26gname%3D%26gtype%3D%26apalic%3D%26tbar%3D1%26pc%3D%26simid%3D%26cap%3D1%26customgeoip%3D%26vd%3D0%26cid%3D%26pe%3D%26so%3D%26lb%3D%26pl%3D0%26plno%3D%26fi%3D0%26langcode%3Den%26upl%3D0%26cufr%3D%26cuto%3D%26howler%3D%26cvrem%3D0%26cvtype%3D0%26cvloc%3D0%26cl%3D0%26upfr%3D%26upto%3D%26primcat%3D%26seccat%3D%26cvcategory%3D*%26restriction%3D%26random%3D%26ispremium%3D1%26flip%3D0%26contributorqt%3D%26plgalleryno%3D%26plpublic%3D0%26viewaspublic%3D0%26isplcurate%3D0%26imageurl%3D%26saveQry%3D%26editorial%3D1%26t%3D0%26filters%3D0">Illustrated London News/Alamy</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Cultural traditions</h2>
<p>The importance of limpets as food was even recognised by the famous Greek playwright <a href="https://www.greekmythology.com/Plays/Aristophanes/aristophanes.html">Aristophanes</a>. His play <a href="_Ecclesiazousae_">Assemblywomen</a> on gender equality includes one of the longest words ever (182 Latin characters), which <a href="https://longestwords.wordpress.com/2008/05/12/lepadotemachoselachogaleokranioleipsanodrimhypotrimmatosilphioparaomelitokatakechymenokichlepikossyphophattoperisteralektryonoptekephalliokigklopeleiolagoiosiraiobaphetraganopterygon/">describes a dish that includes limpets</a> by stringing together its ingredients. And here it is: </p>
<blockquote>
<p>Lepadotemachoselachogaleokranioleipsanodrimhypotrimmatosilphioparaomelitokata-kechymenokichlepikossyphophattoperisteralektryonoptekephalliokigklopeleiolagoiosiraio-baphetraganopterygon.</p>
</blockquote>
<p>Limpets were – and are – also popular as bait for catching fish and crustaceans. In Scotland, it could be argued that an entire <a href="https://dsl.ac.uk/results/limpet/fulltext/withquotes/both/">culture and language</a> has developed around the use of limpets for this purpose, a tradition that is reflected in <a href="https://www.theguardian.com/stage/2009/sep/08/silver-darlings-review">literature</a> and <a href="http://www.songlyrics.com/runrig/rubh-nan-cudaigean-lyrics/">song</a>.</p>
<p>In the past, limpet shells have been used for a wide variety of uses, including tools, currency, offerings, traditional medicine, jewellery and artworks. The “<a href="https://www.papier.com/thefold/articles/the-story-of-sailors-valentines">sailor’s valentine</a>”, which originated in Barbados in the 1830s, is a form of shell craft, a type of souvenir or sentimental gift made from small seashells, with limpets forming a prominent feature. </p>
<p>In Hawaii, limpet shells were placed on shrines, and certain families revered them as their ancestral spirits or “aumakua”. In the east of Scotland, it is thought that limpets were part of the <a href="https://www.cambridge.org/core/journals/proceedings-of-the-prehistoric-society-of-east-anglia/article/abs/evidence-of-human-sacrifice-in-seacliff-cave-scotland/0652521CB7957C3C0AA09625DCD2A32B">ritual of pagan human sacrifice</a>. <a href="https://members.cogwa.org/living-christianity-blog/lessons-from-the-limpet-1/">For Christians</a>, there is also a strong tradition of eating limpets on Good Friday, particularly around the UK, Ireland and the Azores; the steadfast shellfish is an analogy for the way Christians should cling to God – the way a limpet holds tightly to the rocks.</p>
<p>Its symbolism may be mighty, but the humble limpet has been unjustly underestimated. This marine relative of the familiar terrestrial snail helped humans evolve and provided much needed nutrition and physical and cultural nourishment along the way. It was always so much more than the popular notion of famine food and memories of rock pooling adventures. The limpet deserves some proper recognition at last.</p><img src="https://counter.theconversation.com/content/173871/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Firth 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>Without this tiny, ubiquitous shellfish, the story of human life on Earth may have played out quite differently.Louise Firth, Associate Professor in Marine Ecology, University of PlymouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1546342021-02-09T20:13:18Z2021-02-09T20:13:18ZHundreds of fish species, including many that humans eat, are consuming plastic<figure><img src="https://images.theconversation.com/files/383173/original/file-20210209-19-mk7rt.jpg?ixlib=rb-1.1.0&rect=50%2C8%2C5568%2C3659&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A biologist examines microplastics found in sea species at the Hellenic Centre for Marine Research in Greece, Nov. 26, 2019.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/biologist-looks-at-microplastics-found-in-sea-species-at-news-photo/1185691931?adppopup=true">Louisa Gouliamaki/AFP via Getty Images</a></span></figcaption></figure><p>Trillions of <a href="https://theconversation.com/far-more-microplastics-floating-in-oceans-than-thought-51974">barely visible pieces of plastic</a> are floating in the world’s oceans, from surface waters to the <a href="https://doi.org/10.1038/s41598-019-44117-2">deep seas</a>. These particles, known as microplastics, typically form when larger plastic objects such as shopping bags and food containers break down. </p>
<p>Researchers are concerned about microplastics because they are minuscule, widely distributed and easy for wildlife to consume, <a href="https://theconversation.com/bait-and-switch-anchovies-eat-plastic-because-it-smells-like-prey-81607">accidentally or intentionally</a>. We study <a href="https://scholar.google.com/citations?user=uo1sSBwAAAAJ&hl=en">marine science</a> and <a href="https://scholar.google.com/citations?user=8Gb9COIAAAAJ&hl=en">animal behavior</a>, and wanted to understand the scale of this problem. In a newly published study that we conducted with ecologist <a href="https://scholar.google.com/citations?user=mI9gJxIAAAAJ&hl=en">Elliott Hazen</a>, we examined how marine fish – including species consumed by humans – are ingesting synthetic particles of all sizes. </p>
<p>In the broadest review on this topic that has been carried out to date, we found that, so far, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.15533">386 marine fish species are known to have ingested plastic debris</a>, including 210 species that are commercially important. But findings of fish consuming plastic are on the rise. We speculate that this could be happening both because detection methods for microplastics are improving and because ocean plastic pollution continues to increase.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LiH3f6AKFbc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Researchers at California’s Monterey Bay Aquarium have found microplastic particles from the surface to the seafloor, where they can be ingested by a wide range of sea creatures.</span></figcaption>
</figure>
<h2>Solving the plastics puzzle</h2>
<p>It’s not news that wild creatures ingest plastic. The first scientific observation of this problem came <a href="https://doi.org/10.2307/4083505">from the stomach of a seabird in 1969</a>. Three years later, scientists reported that fish off the coast of southern New England were <a href="http://dx.doi.org/10.1126/science.178.4062.749">consuming tiny plastic particles</a>.</p>
<p>Since then, well over 100 scientific papers have described plastic ingestion in numerous species of fish. But each study has only contributed a small piece of a very important puzzle. To see the problem more clearly, we had to put those pieces together.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>This story is part of <a href="https://theconversation.com/uk/topics/oceans-21-96784">Oceans 21</a></em></strong>
<br>Our series on the global ocean opened with <a href="https://oceans21.netlify.app/">five in depth profiles</a>. Look out for new articles on the state of our oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.</p>
<hr>
<p>We did this by creating the largest existing database on plastic ingestion by marine fish, drawing on every scientific study of the problem published from 1972 to 2019. We collected a range of information from each study, including what fish species it examined, the number of fish that had eaten plastic and when those fish were caught. Because some regions of the ocean have more plastic pollution than others, we also examined where the fish were found. </p>
<p>For each species in our database, we identified its diet, habitat and feeding behaviors – for example, whether it preyed on other fish or grazed on algae. By analyzing this data as a whole, we wanted to understand not only how many fish were eating plastic, but also what factors might cause them to do so. The trends that we found were surprising and concerning.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Plastic bag drifting in shallow water." src="https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/383117/original/file-20210208-17-6vwa8h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leopard sharks swim past plastic debris in shallow water off southern California.</span>
<span class="attribution"><a class="source" href="https://www.ralphpace.com">Ralph Pace</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>A global problem</h2>
<p>Our research revealed that marine fish are ingesting plastic around the globe. According to the 129 scientific papers in our database, researchers have studied this problem in 555 fish species worldwide. We were alarmed to find that more than two-thirds of those species had ingested plastic.</p>
<p>One important caveat is that not all of these studies looked for microplastics. This is likely because finding microplastics requires specialized equipment, like microscopes, or use of more complex techniques. But when researchers did look for microplastics, they found five times more plastic per individual fish than when they only looked for larger pieces. Studies that were able to detect this previously invisible threat revealed that plastic ingestion was higher than we had originally anticipated.</p>
<p>Our review of four decades of research indicates that fish consumption of plastic is increasing. Just since an international <a href="http://www.gesamp.org/publications/microplastics-in-the-marine-environment-part-2">assessment conducted for the United Nations in 2016</a>, the number of marine fish species found with plastic has quadrupled. </p>
<p>Similarly, in the last decade alone, the proportion of fish consuming plastic has doubled across all species. Studies published from 2010-2013 found that an average of 15% of the fish sampled contained plastic; in studies published from 2017-2019, that share rose to 33%.</p>
<p>We think there are two reasons for this trend. First, scientific techniques for detecting microplastics have improved substantially in the past five years. Many of the earlier studies we examined may not have found microplastics because researchers couldn’t see them. </p>
<p>Second, it is also likely that fish are actually consuming more plastic over time as ocean plastic pollution <a href="http://dx.doi.org/10.1126/science.aba9475">increases globally</a>. If this is true, we expect the situation to worsen. Multiple studies that have sought to quantify plastic waste project that the amount of plastic pollution in the ocean will <a href="http://dx.doi.org/10.1126/science.aba3656">continue to increase</a> over the <a href="http://dx.doi.org/%2010.1126/sciadv.1700782">next several decades</a>.</p>
<p><iframe id="vmUzZ" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/vmUzZ/3/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>Risk factors</h2>
<p>While our findings may make it seem as though fish in the ocean are stuffed to the gills with plastic, the situation is more complex. In our review, almost one-third of the species studied were not found to have consumed plastic. And even in studies that did report plastic ingestion, researchers did not find plastic in every individual fish. Across studies and species, about one in four fish contained plastics – a fraction that seems to be growing with time. Fish that did consume plastic typically had only one or two pieces in their stomachs. </p>
<p>In our view, this indicates that plastic ingestion by fish may be widespread, but it does not seem to be universal. Nor does it appear random. On the contrary, we were able to predict which species were more likely to eat plastic based on their environment, habitat and feeding behavior. </p>
<p>For example, fishes such as sharks, grouper and tuna that hunt other fishes or marine organisms as food were more likely to ingest plastic. Consequently, species higher on the food chain were at greater risk. </p>
<p>We were not surprised that the amount of plastic that fish consumed also seemed to depend on how much plastic was in their environment. Species that live in ocean regions known to have a lot of plastic pollution, such as the Mediterranean Sea and the coasts of East Asia, were found with more plastic in their stomachs. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1339067730306031618"}"></div></p>
<h2>Effects of a plastic diet</h2>
<p>This is not just a wildlife conservation issue. Researchers don’t know very much about the effects of ingesting plastic on fish or humans. However, there is evidence that that microplastics and even smaller particles called <a href="https://doi.org/10.1038/s41565-019-0437-7">nanoplastics</a> can move from a fish’s stomach to its <a href="https://doi.org/10.1016/j.scitotenv.2019.134625">muscle tissue</a>, which is the part that humans typically eat. Our findings highlight the need for studies analyzing how frequently plastics transfer from fish to humans, and their potential effects on the human body.</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>Our review is a step toward understanding the global problem of ocean plastic pollution. Of more than 20,000 marine fish species, only roughly 2% have been tested for plastic consumption. And many reaches of the ocean remain to be examined. Nonetheless, what’s now clear to us is that “out of sight, out of mind” is not an effective response to ocean pollution – especially when it may end up on our plates.</p><img src="https://counter.theconversation.com/content/154634/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexandra McInturf is affiliated with The Ethogram (<a href="https://theethogram.com/">https://theethogram.com/</a>). </span></em></p><p class="fine-print"><em><span>Matthew Savoca receives funding from The National Geographic Society and the National Science Foundation. </span></em></p>As more and more plastic trash permeates the oceans, fragments are making their way into fish and shellfish – and potentially into humans.Alexandra McInturf, PhD Candidate in Animal Behavior, University of California, DavisMatthew Savoca, Postdoctoral researcher, Stanford UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1462912020-11-12T13:25:32Z2020-11-12T13:25:32ZAmericans don’t eat enough fish and miss out on robust health benefits<figure><img src="https://images.theconversation.com/files/362000/original/file-20201006-18-sjzgsw.jpg?ixlib=rb-1.1.0&rect=0%2C307%2C3019%2C3721&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sardines are rich in oils and protein.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/9I3aLTYnWa4">Photo by Ahmed Nadar for Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><figure class="align-center ">
<img alt="26 lbs. - Recommended annual amount of seafood that Americans should eat" src="https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368646/original/file-20201110-15-ov7t7r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Eating fish can provide powerful advantages for the <a href="https://www-tandfonline-com.ezproxy.lib.umb.edu/doi/pdf/10.1080/10408398.2018.1425978?needAccess=true">heart and brain</a>, yet Americans eat <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353403/">less than half</a> of the 26 pounds per year that experts recommend. By contrast, Americans buy <a href="https://www.ers.usda.gov/data-products/ag-and-food-statistics-charting-the-essentials/food-availability-and-consumption/">seven times more chicken and beef</a> annually than fish. </p>
<p>Why Americans don’t eat more fish has been pondered <a href="https://www.theatlantic.com/health/archive/2012/11/how-to-get-americans-to-eat-fish/265150/">for a long time</a> by health experts, fish farmers and fishermen themselves. One way to consider this question is production. Consumers can buy a product only if it’s available. The more they buy, theoretically, the more that item will be produced. In this case, a greater demand for fish would be stimulated if more fish were offered for sale. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Wild-caught salmon from the Pacific Ocean are a prized fish for consumers." src="https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=494&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=494&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359146/original/file-20200921-22-1pcuggj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=494&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Salmon caught in the Pacific Ocean is a prize catch.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/xp3xtQW3pqs">Photo by NOAA for Unsplash.</a></span>
</figcaption>
</figure>
<p>More seafood could be made available for American consumers from <a href="https://oceanpanel.org/sites/default/files/2019-11/19_HLP_BP1%20Paper.pdf">global ocean sources</a> given that at least <a href="https://doi.org/10.1073/pnas.1905650116">60% of seafood</a> in the U.S. is imported. U.S. aquaculture has the capacity to <a href="https://blogs.scientificamerican.com/observations/its-time-to-be-honest-about-seafood/">significantly increase</a>. Research conducted by the <a href="https://www.fisheries.noaa.gov/national/population-assessments/status-us-fisheries">National Oceanic and Atmospheric Administration Fisheries</a> also indicates slightly more domestic wild-caught fish can be harvested. </p>
<h2>Why eat fish?</h2>
<p>Rich in lean protein and long chain omega-3 fatty acids, fish provides robust nutritional benefits that can help ward off <a href="https://www.seafoodnutrition.org/press-releases/eat-seafood-america-boost-health/">chronic disease, boost immunity and reduce inflammation</a> in the body. Seafood provides your body with critical omega-3 fats and minerals, like selenium, zinc, iron and iodine. It also provides vitamins B12 and D that fend off heart disease, among other benefits. </p>
<p>Fish provides such positive benefits for the body that recent <a href="https://www.dietaryguidelines.gov/2020-advisory-committee-report">USDA Dietary Guidelines</a> offer guidance specific to pregnant women and children based on the finding that seafood consumption leads to <a href="https://doi.org/10.1016/j.plefa.2019.10.001">cognitive improvement in children</a>. Research shows that integrating seafood into a diet as a way to prevent coronary disease can lead to a potential annual health care <a href="https://doi.org/10.1371/journal.pmed.1002981">savings of US$12.7 billion</a>.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Wild Pacific Ocean Dungeness crab." src="https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359148/original/file-20200921-18-1mikw8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dungeness crab are fished off the Pacific coast from California to the Gulf of Alaska.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/Mqe3P62_Nfc">Photo by Sidney Pearce for Unsplash</a></span>
</figcaption>
</figure>
<p>Additionally, seafood, as a protein, has a relatively <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/fee.1822">low greenhouse gas production</a>. This benefit is heightened when analyzing the <a href="https://doi.org/10.1016/j.jclepro.2019.04.229">many species</a> that offer both high nutrient density and low greenhouse gas production. </p>
<h2>Fish beyond shrimp</h2>
<p>The <a href="https://health.gov/sites/default/files/2019-09/2015-2020_Dietary_Guidelines.pdf">2015-2020 USDA Dietary Guidelines</a> suggest that Americans eat 26 pounds of seafood each year. The recommended amount would ideally provide 250 mg per day of the important omega-3 fats. Yet because of how American consumers purchase seafood, this provides them with, on average, only 38% of the recommended daily omega-3’s.</p>
<p>Many of the most popular seafoods purchased by consumers are relatively low in omega-3’s, such as shrimp, the most popular seafood in the U.S., comprising nearly 30% of annual fish sales. Considering the <a href="https://www.intrafish.com/markets/here-are-americas-most-consumed-seafood-species/2-1-760884">10 species</a> that make up 85% of fish available for Americans to buy in restaurants and markets, only salmon, the second most popular seafood item, has <a href="https://www.seafoodnutrition.org/wp-content/uploads/2020/03/RDN-Toolkit-2020_Omega3-Chart.pdf">relatively high levels of omega-3’s</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Eat fish more often." src="https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359144/original/file-20200921-24-k77m33.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">Fish oil can protect the heart.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/GbfBGZ5Netw">Photo by Gunnar Ridderstrom for Unsplash.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>There are many species of fish high in omega-3’s that are not regularly purchased or eaten, such as anchovies, herring and sardines. People can replace eating fish by <a href="https://doi.org/10.3390/nu11010177">taking supplements</a> or eating other foods, <a href="https://doi.org/10.1016/j.japr.2019.10.002">such as eggs</a> that contain omega-3’s, to help overcome this deficiency. However, research shows that eating fish itself is <a href="https://link.springer.com/article/10.1007/s11745-003-1077-x">better</a> than supplements, given that a fish filet has a full complement of <a href="https://www.health.harvard.edu/blog/fish-oil-friend-or-foe-201307126467">fats, vitamins, minerals and other supporting molecules</a>. </p>
<p>The health and environmental benefits of fish make it a smart choice to buy and eat. With more people <a href="https://www.forbes.com/sites/daphneewingchow/2020/03/31/five-ways-that-coronavirus-will-change-the-way-we-eat/#241f04ae1a2b">at home</a> because of the pandemic, this is a good time to explore <a href="https://www.seafoodnutrition.org/recipes/">recipes</a> and <a href="https://www.thespruceeats.com/seafood-basics-4162172">enjoy</a> this nutritionally important food. </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><img src="https://counter.theconversation.com/content/146291/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Tlusty receives funding from the National Science Foundation, the Atlantic States Marine Fisheries Commission, and the National Sea Grant College Program. He is on the Science and Nutrition Advisory Council of the Seafood Nutrition Partnership, a judge for the F3 Challenge, a board member for the Center for Responsible Seafood, and on the Advisory Committee of the Marine Conservation Action Fund.</span></em></p>The oils in fish are excellent buffers against disease. Why don’t we eat more fish?Michael Tlusty, Associate Professor of Sustainability and Food Solutions, UMass BostonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1494102020-11-05T15:16:32Z2020-11-05T15:16:32ZMetal pollution is leaving scallops helpless against crabs and lobsters<figure><img src="https://images.theconversation.com/files/367728/original/file-20201105-20-iif35j.JPG?ixlib=rb-1.1.0&rect=8%2C0%2C5455%2C3071&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Will Notley</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Shellfish such as scallops, mussels and oysters – bivalve molluscs – <a href="http://www.int-res.com/abstracts/meps/v211/p157-167/">readily take up tiny specs of metals</a> into their tissues and shells. In sufficient concentrations this can harm their growth and survival chances, and even threaten the health of any human who eats their contaminated meat. Such shellfish provide <a href="http://www.fao.org/state-of-fisheries-aquaculture">one-quarter of the world’s seafood</a>, so the impact of pollution from the “heavy metals” such as lead, zinc and copper, is hugely important.</p>
<p>We recently investigated the effects of metal pollution on the great scallop, <em>Pecten maximus</em>, for a new <a href="https://www.sciencedirect.com/science/article/pii/S0048969720365499">scientific study</a>. This is a common species which supports the <a href="https://www.gov.uk/government/statistics/uk-sea-fisheries-annual-statistics-report-2019">most valuable fishery</a> in England and the third most valuable in the UK overall. </p>
<p>We first discovered these effects of pollution by chance. While carrying out routine stock assessment surveys around the Isle of Man, a self-governing island that lies between Britain and Ireland, we noticed that scallops found on the Laxey fishing ground off the east coast were much more likely to have lethally damaged shells than scallops from elsewhere.</p>
<p>Laxey is famous for the world’s largest working <a href="https://www.visitisleofman.com/experience/great-laxey-wheel-and-mine-trail-p1292251">waterwheel</a>, a spectacular example of Victorian engineering used to pump water <a href="https://www.nmrs.org.uk/mines-map/metal/isle-man-mines/laxey-mine/">from a mine</a> which produced lead, copper, silver and zinc. The mine closed in 1929, but its legacy is that sediments in the rivers, estuary and sea waters around Laxey are unnaturally high in metals. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large red and white wheel next to a tower." src="https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367722/original/file-20201105-17-1tjxqsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The 22-metre diameter Laxey Wheel is now a tourist attraction.</span>
<span class="attribution"><span class="source">Powerofflowers / shutterstock</span></span>
</figcaption>
</figure>
<p>It looked as though metal pollution may be responsible for the damaged shells we discovered. To test this hypothesis, we analysed the strength of scallop shells that had been collected from Laxey and other fishing grounds around the Isle in both 2004 and 2013. In both groups the shells from Laxey were found to be significantly weaker than those from all other areas.</p>
<p>A detailed analysis revealed the Laxey shells were proportionally thinner than shells found at other areas, and that the internal structure of shells contained a disruption, or fault line. We were not able to detect metals in the shells themselves, but we think that even in low quantities the metals are either affecting the physiology of the scallops or disrupting chemical reactions during the mineralisation (shell-growing) process.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of heavy metal pollution and impact on scallops." src="https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367727/original/file-20201105-21-1ke2lxx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scallops with unnaturally thin shells are also more likely to be damaged when being captured.</span>
<span class="attribution"><span class="source">Stewart et al (2020)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In ecotoxicology terms, what we observed is called a <a href="https://www.oecd.org/chemicalsafety/testing/49963576.pdf">non-apical endpoint effect</a>. Weakened shells don’t directly kill scallops, but instead leave them more vulnerable to mortality. Such responses are rarely considered when assessing the effects of environmental contaminants, but could have significant implications. This is a concern, because the levels of metal contamination we observed were generally below the current regulatory limits thought to affect marine life, and the scallops were considered perfectly safe to eat.</p>
<h2>Metals at sea</h2>
<p>It is remarkable that mining from 100 years ago is still affecting marine life in this way. But, given that metal contamination is <a href="https://link.springer.com/article/10.1007/s40726-015-0018-9">a common and increasing threat</a> in coastal areas around the world, and that many other shellfish and marine species such as corals produce calcified structures chemically-similar to scallop shells, we believe metals may be having unseen effects on a large scale. We may therefore need to rethink how we assess and manage the risks of metal contamination.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo showing four scallop shells" src="https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=665&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=665&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=665&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=836&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=836&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367729/original/file-20201105-16-rc110n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=836&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">King scallops showing different levels of damage after being caught in dredges around the Isle of Man. This type of damage is much more likely in areas contaminated with heavy metals.</span>
<span class="attribution"><span class="source">Bryce Stewart</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Metals are a natural component of marine systems and in trace concentrations may be essential for supporting life. However, human activities have <a href="https://oap.ospar.org/en/ospar-assessments/intermediate-assessment-2017/pressures-human-activities/contaminants/metals-fish-shellfish/">elevated their concentrations</a> in many marine environments to the point where they have become toxic. This pollution comes from <a href="https://scialert.net/fulltext/?doi=jas.2004.1.20">a variety of sources</a> such as run off from mining, agricultural and industrial activity; offshore oil and gas exploitation; and leaching of anti-fouling paint from ships hulls. As a result, metal pollution tends to be highest in estuaries, around ports and in inshore waters. </p>
<p>Despite stricter recent regulations controlling the use of metals in marine environments, they continue to be an increasing threat. This is because heavy metals are highly persistent (they do not disappear over time) and ongoing coastal development and bottom-towed fishing gear is <a href="https://www.sciencedirect.com/science/article/abs/pii/S0269749112003284">remobilising contaminated sediments</a>. Climate change is also <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12048">exacerbating the threat</a> because higher rainfall is increasing run-off from contaminated areas, and ocean warming and acidification is increasing the rate of uptake and toxicity of metals in seawater.</p>
<p>Most previous studies have concentrated on the direct effects of metals on shellfish <a href="https://www.sciencedirect.com/science/article/abs/pii/0141113687900523">survival</a> or <a href="https://www.sciencedirect.com/science/article/pii/B9780081006740000217">food safety</a>. However, our new study has unearthed that even relatively low concentrations of metal contamination appears to be causing scallops to grow weaker shells. This leaves the scallops more vulnerable to being <a href="https://link.springer.com/article/10.1007/s00227-002-0977-4">eaten by crabs and lobsters</a> and to disturbance from storms and fishing activity, with potentially substantial ecological and economic repercussions.</p><img src="https://counter.theconversation.com/content/149410/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bryce Stewart receives funding from the European Maritime and Fisheries Fund, the Economic and Social Research Council, the Global Challenges Research Fund and the Blue Marine Foundation. He is a member of the ICES Scallop Working Group, the Marine Conservation Society and the Yorkshire Wildlife Trust </span></em></p><p class="fine-print"><em><span>Roland Kröger receives funding from EPSRC, NERC, Leverhulme Trust, European Comission. </span></em></p>New research points to ‘heavy metals’ having unseen effects on a much larger scale than previously thought.Bryce Stewart, Senior Lecturer in Marine Ecosystem Management, University of YorkRoland Kröger, Professor, Department of Physics, University of YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1384052020-06-03T12:15:15Z2020-06-03T12:15:15ZParasitic worms in your shellfish lead a creepy but popular lifestyle<figure><img src="https://images.theconversation.com/files/336189/original/file-20200519-152344-gc94zt.jpg?ixlib=rb-1.1.0&rect=1%2C2%2C697%2C520&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Parasites do very well for themselves, which is why they are so common in the animal kingdom.</span> <span class="attribution"><a class="source" href="http://www.marinespecies.org/introduced/aphia.php?p=image&pic=99515">Geoffrey Read</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>If you’re an oyster lover, seeing a shaggy worm slither across your appetizer is revolting – even though such worms are harmless to people. An internet search using the keywords “oyster” and “worm” will bring up a large cache of images, each one less palatable than the next. </p>
<p>As a <a href="https://scholar.google.com/citations?user=DtgT_YIAAAAJ&hl=en">biologist</a>, I study invasive species including these mud blister worms. Despite their high gross-out factor, their parasitic lifestyles are fascinating. While parasites do cause harm to their hosts, they are also a crucial piece of the planet’s ecosystem.</p>
<h2>Shell-boring worms</h2>
<p>Mud blister worms belong to a larger group of segmented worms, collectively known as <a href="https://www.smithsonianmag.com/science-nature/14-fun-facts-about-marine-bristle-worms-180955773/">polychaetes</a>. “Poly” means many and “chaete” means bristles in ancient Greek. Mud blister worms are one of many species that burrow into the shells of animals like oysters, abalone and scallops, where they spend their entire adult life.</p>
<p>Considering the shells of oysters and scallops are made up of calcium carbonate, which has limited nutritional value, it might seem an odd location for a worm infestation. But rather than feeding on the shell itself, these worms create an amazing network of tunnels within the shell’s matrix, using it as a house rather than a food source. </p>
<figure>
<img src="https://cdn.theconversation.com/static_files/files/1045/vl6Q3M.gif?1589988051" width="100%">
<figcaption><span class="caption">This worm, <i>Polydora cornutanhas</i>, uses tentacles to snag passing algae and food particles, while its body remain safely ensconced in the shell of its host organism.</span></figcaption>
</figure>
<p>The worms feed by protruding their tentacles out of tiny openings in the shell, where they capture food particles from the surrounding seawater. Unlike other parasites, which feed directly on their hosts, mud blister worms invade their hosts’ outer covering and must have food delivered to them for survival.</p>
<p>How many worms can a single shell harbor? I once counted more than 120 worms emerging from the shell of a heavily infested Pacific oyster. The surface of the oyster looked like any other, but once it was immersed into a special irritating solution, a stunning number of worms began to rise up, just like a creature in a zombie film. </p>
<h2>Sibling cannibalism</h2>
<p>Adult worms are sedentary, meaning they remain within the tunnels they create and do not actively leave their quarters. The offspring of these worms, however, are free-swimming larvae, which are released into the water column after birth and <a href="https://doi.org/10.1007/s00227-013-2388-0">disperse the species throughout the ocean</a>. </p>
<p>After mating, females produce an egg case containing thousands of eggs, some of which hatch into larvae and some of which do not hatch at all. The latter become “nurse eggs,” or food that <a href="https://doi.org/10.1007/s00227-013-2388-0">nourish the developing offspring</a>. This is where things get interesting. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/zqXuh82_D6c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">It’s ‘eat or be eaten’ among larvae.</span></figcaption>
</figure>
<p>In one of my earliest <a href="http://hdl.handle.net/10019.1/96594">studies of these worms</a>, my colleagues and I found that in situations where nurse eggs were depleted, larger larvae often viciously attacked and cannibalized their siblings within the egg case. In other situations, the cannibalism occurred even in the presence of nurse eggs. </p>
<p>The mother is in charge of releasing the larvae, using a <a href="https://doi.org/10.1016/j.jembe.2014.07.012">pair of tentacles to rupture the egg</a> cases at a time of her choosing. Because she is solely responsible for liberating the offspring from the egg case, she has complete <a href="https://doi.org/10.1016/j.jembe.2014.07.012">control over which siblings live and which die</a>. </p>
<p>Sibling cannibalism, as brutal as it sounds, is actually quite common across the <a href="https://doi.org/10.1016/j.aaf.2016.12.001">animal</a> <a href="https://doi.org/10.1111/j.1439-0310.2010.01792.x">kingdom</a>. Sand tiger sharks, for example, exhibit a similar behavior where <a href="https://doi.org/10.1098/rsbl.2013.0003">siblings fight each other to the death</a> in the womb although, in this case, the mother shark does not exert as much control as a mud blister worm matriarch does. </p>
<p>The evolutionary significance of sibling cannibalism – and why it seems to have emerged in animals as far apart on the tree of life as worms and sharks – is still not fully known and remains an <a href="https://doi.org/10.1073/pnas.1911677117">active area of evolutionary biology research</a>. </p>
<h2>Threats to humans and the aquaculture industry</h2>
<p>Luckily, shell-boring worms pose no threat to humans. Aside from an unexpected protein boost, accidental consumption will not lead to any health problems. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Oysters under siege.</span>
<span class="attribution"><a class="source" href="https://youtu.be/zqXuh82_D6c">Federal University of Recôncavo da Bahia and State University of Santa Cruz</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>However, these worms are <a href="https://www.adfg.alaska.gov/static/species/disease/pdfs/bivalvediseases/shellboring_polychaetes.pdf">notorious pests in the aquaculture industry</a>. Heavy infestations can cause reduced growth in shellfish, because the mollusk must <a href="https://www.int-res.com/abstracts/aei/v7/n2/p147-166/">divert energy from growth to shell repair</a>. In addition, the meat of infested oysters has been reported as having a <a href="http://masgc.org/projects/details/maximizing-the-return-on-investment-of-oyster-aquaculture-by-managing-mud-b">more “watery” consistency</a> than uninfested oysters. Together, these effects result in a commercial loss for aquaculture farms. </p>
<p>In past years, scientist have proposed the <a href="https://doi.org/10.1016/j.aquaculture.2010.10.031">use of chemical compounds</a> and the <a href="https://doi.org/10.1016/0044-8486(95)01212-5">heat-shocking of oysters</a> to control the worms, but there has yet to be a silver bullet for eradication. </p>
<p>Perhaps one of the most overlooked facts in zoology is that parasitism is the <a href="https://doi.org/10.1016/j.biocon.2010.10.025">most predominant lifestyle on Earth</a> and plays an important role in maintaining ecosystems by <a href="https://doi.org/10.1007/s10393-004-0028-3">stabilizing food webs and regulating population sizes</a>. Like many marine invertebrates, the larvae of these worms serve as planktonic food for animals higher up in the food chain, thereby <a href="https://doi.org/10.1093/icb/icq037">contributing to the overall structure of the marine community</a>. </p>
<p>So next time you are at a seafood restaurant and you order a couple of raw oysters, try breaking apart the shells – perhaps after you’ve finished eating. You might discover a few hidden freeloaders. </p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>.]</p><img src="https://counter.theconversation.com/content/138405/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Davinack does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Mud blister worms make their homes in the shells of oysters and other shellfish, where they weaken their hosts.Andrew Davinack, Assistant Professor of Biology, Clarkson UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1186682019-08-13T22:17:20Z2019-08-13T22:17:20ZThe demand for luxury shellfish is polluting the ocean with plastic<figure><img src="https://images.theconversation.com/files/287411/original/file-20190808-144855-jh0m8e.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5155%2C3261&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Segments of PVC pipe washed up on shore in Denman Sound, B.C. </span> <span class="attribution"><span class="source">Paul Nicklen/Sea Legacy</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The federal government has taken action recently to reduce the amount of plastic waste found on land and in oceans, rivers and lakes. </p>
<p>In June, for example, it said it would <a href="https://pm.gc.ca/eng/news/2019/06/10/canada-ban-harmful-single-use-plastics-and-hold-companies-responsible-plastic-waste">ban single-use plastics by 2021</a>. “It is tough to explain to your children why <a href="https://pm.gc.ca/en/news/speeches/2019/06/14/prime-ministers-speaking-notes-plastics-announcement">dead whales are washing up on our beaches with their stomachs jammed packed with plastic bags</a>,” Prime Minister Justin Trudeau commented at the time. </p>
<p>Despite this progress, one of the main plastic polluters — shellfish aquaculture — continues to threaten marine ecosystems. </p>
<p>Coastal British Columbia is rugged and jagged. Its drowned fjords are home to wild salmon and the ecosystems that depend on them. Tucked away between Vancouver and Denman islands is Baynes Sound, a serene inland sea, home to sea mammals, globally important duck and bird populations, and a <a href="https://www.crcpress.com/Stewarding-the-Sound-The-Challenge-of-Managing-Sensitive-Coastal-Ecosystems/Bendell-Gallaugher-Wood-McKeachie/p/book/9780367112035">biological diversity unmatched along our coast</a>. </p>
<p>So unique is this ecosystem that, 20 years ago, the Department of Fisheries and Oceans (DFO) <a href="http://publications.gc.ca/site/eng/9.807120/publication.html">recommended regions within this area be set aside as protected areas</a>.</p>
<p>Threats to the sound include increased tourism, urbanization and an-as-yet-unregulated seaweed harvest. The greatest threat, however, is an expanding shellfish industry that provides a continual source of plastics to the sound. </p>
<h2>Shellfish aquaculture</h2>
<p>For the past 14 years, community beach cleanups have measured the plastic in Baynes Sound. An astonishing four to six tonnes of plastic debris, including anti-predator netting, plastics trays, ropes and styrofoam, is collected from the beaches annually. Now polyvinyl chloride (PVC) piping, used for the farming of geoducks is also being washed ashore. </p>
<p>In 2017, the DFO gave the West Coast shellfish industry a green light to expand its farming practices to include the lucrative geoduck, a luxury protein used in sashimi, to meet the demand from Hong Kong and the rest of China.</p>
<p>Geoducks (pronounced “gooey ducks”) are large salt-water clams, found naturally along the Pacific coast. Sales of farmed geoduck to this select market <a href="https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/statistics/industry-and-sector-profiles/year-in-review/bcseafood_yearinreview_2017.pdf">netted close to $56 million in 2017</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281879/original/file-20190629-94688-h3c8x9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Rows of PVC piping inserted into the beach shoreline for geoduck farming.</span>
<span class="attribution"><span class="source">Association for Denman Island Marine Stewards</span></span>
</figcaption>
</figure>
<p>Farming them involves placing juvenile geoducks into rows and rows of 18-inch long segments of PVC piping, planted vertically into the intertidal sediments, at a density of one pipe per square foot. Nets are secured with elastic bands over the pipe to protect the immature geoduck. </p>
<p>But <a href="http://coalitiontoprotectpugetsoundhabitat.org/?page_id=493">the pipes become loose within days, especially after storm events</a>, and the beach becomes littered with the plastic netting, elastics and pipes. Wave action and ultraviolet light from the sun degrade the pipes, creating fragments and then microplastics (items smaller than five millimetres in diametre) that further pollute the marine environment. </p>
<h2>Ecosystem and health impacts</h2>
<p>PVC is <a href="https://www.thermofisher.com/blog/materials/polymer-profiles-a-guide-to-the-worlds-most-widely-used-plastics/">one of the most common plastic polymers</a> in use, and <a href="http://dx.doi.org/10.1021/acs.est.6b02569">its breakdown can damage ecosystem and human health</a>. </p>
<p>The particles may <a href="http://www.gesamp.org/publications/reports-and-studies-no-90">harm invertebrates, fish, seabirds and other organisms that consume them</a>. The chemicals in the plastic debris, including plasticizers, phthalates, flame retardants and stabilizers, can <a href="https://www.epa.gov/sites/production/files/2016-12/documents/plastics-aquatic-life-report.pdf">leach out of particles and have the potential to harm marine organisms</a>. Finally, the pipe fragments can also act as a substrate, providing <a href="http://www.gesamp.org/publications/reports-and-studies-no-90">pathogenic marine organisms and parasites in near-shore environments with a place to grow and multiply</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287416/original/file-20190808-144873-30344f.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">Live geoducks in a restaurant tank.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>“Canadians know first-hand the impacts of plastic pollution, and are tired of seeing their beaches, parks, streets and shorelines littered with plastic waste,” Trudeau said in a statement after he announced the single-use plastics ban. </p>
<blockquote>
<p>“We have a responsibility to work with our partners to reduce plastic pollution, protect the environment and create jobs and grow our economy. <a href="https://pm.gc.ca/eng/news/2019/06/10/canada-ban-harmful-single-use-plastics-and-hold-companies-responsible-plastic-waste">We owe it to our kids to keep the environment clean and safe for generations to come</a>.”</p>
</blockquote>
<p>So, why the paradox? </p>
<p>The government says it’s <a href="https://www.dfo-mpo.gc.ca/acts-lois/rules-reglements/rule-reglement04-eng.htmlink">intent on protecting at least 10 per cent of our coastal ecosystems</a> and reducing the threat of plastics to our marine environments. Yet the industry, which is managed by our federal government, has been given permission to introduce hazardous plastics into one of B.C.’s most sensitive ecosystems. </p>
<p>The ban on plastic holds consumers accountable. It targets their behaviour and will force change. But this is only part of the problem. </p>
<p>The other part of the problem is the industry practice of discharging dangerous plastics into sensitive ecosystems. Government is regulating a change in consumer behaviour. Why not do the same for industry? </p>
<p>If the government’s goal is to protect these sensitive marine ecosystems, it needs to stop the flow of plastics from industrial sources including the unregulated shellfish industry. The economic gain of farming sashimi for a select market is not worth the environmental cost.</p>
<p><em>Shelley McKeachie, a founding member, past chair and director of the Association for Denman Island Marine Stewards, co-authored this article.</em></p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/118668/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leah Bendell 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>Growing demand for large salt-water clams is leaving parts of the B.C. coast littered with plastic debris.Leah Bendell, Professor of Marine Conservation and Ecotoxicology, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1121432019-03-11T19:03:46Z2019-03-11T19:03:46ZShellfish allergies: can they be treated?<figure><img src="https://images.theconversation.com/files/260734/original/file-20190225-26174-14nymou.jpg?ixlib=rb-1.1.0&rect=2%2C26%2C794%2C507&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Shrimp cocktail: Tasty to some, potentially deadly for others.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Cocktail_sauce#/media/File:Cocktail_1_bg_060702.jpg">Legoktm/Wikimedia</a></span></figcaption></figure><p>Seafood platters? Bouillabaisse? Arroz de Marisco? Seafood paella? Oysters Rockefeller? Lobster Thermidor? Dining out with friends, a romantic meal, celebrating Christmas or a holiday on a wind-swept coast with these seafood dishes on your table are enjoyable moments.</p>
<p>But have any of you, your friends or family experienced swelling of lips or eyelids, itchiness and rashes developed over your face or body, or even difficulty in breathing just a few minutes after eating shrimp, lobster, crab, clam, mussels, oysters or scallops? If yes, you could well have a shellfish allergy.</p>
<h2>What is shellfish allergy?</h2>
<p>Shellfish allergy is a type of hyper-immune response mediated by <a href="https://fr.wikipedia.org/wiki/Immunoglobuline_E">Immunoglobulin E</a> (IgE), an antibody produced by B cells.</p>
<p>When someone who is allergic eats some shellfish, the allergens – primary <a href="https://en.wikipedia.org/wiki/Tropomyosin">tropomyosin</a>, a muscle protein – bind with IgE. This allergen-IgE complex then cross-links on mast cells. These cells play a key role in the inflammatory process, by which they contain many granules rich in inflammatory mediators like <a href="https://en.wikipedia.org/wiki/Histamine">histamine</a>. Histamine can increase the permeability of the blood capillaries, exert effects on mucous glands and bronchila tubes, and is a central mediator of allergic reactions like itching.</p>
<h2>A lifelong condition</h2>
<p>As designated by the United States <a href="https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/Allergens/ucm106890.htm">Food Allergen Labelling and Consumer Protection Act</a>, crustacean shellfish are one of the top eight allergens alongside with milk, eggs, peanuts, tree nuts, wheat, soybeans and fish accounting for 90% of food-related allergic reactions.</p>
<p>Unlike allergies to egg and cow’s milk for which children often gradually acquire <a href="https://link.springer.com/article/10.1007%2Fs11882-016-0627-4">natural tolerance</a>, shellfish allergies usually <a href="https://link.springer.com/article/10.1007%2Fs11882-016-0627-4">persist throughout life</a>.</p>
<p>Shellfish is the leading offending food in the United States, Canada, Portugal, and in the Asia-Pacific regions, including <a href="https://www.ncbi.nlm.nih.gov/pubmed/18808390">Hong Kong and Taiwan</a>. A <a href="https://www.ncbi.nlm.nih.gov/pubmed/24372074">multi-centre survey</a> conducted in Europe, on the other hand, reported 4.8% of adults with IgE sensitisation to shrimp and in some areas like Zurich, the sensitisation rate can be up to 7%.</p>
<h2>Poor diagnosis</h2>
<p>Despite such a high impact, diagnosis and treatment of shellfish allergy remains suboptimal. The standard clinical diagnostic involves a thorough review of a patient’s clinical history followed by <a href="https://www.mayoclinic.org/tests-procedures/allergy-tests/about/pac-20392895">skin prick test</a> (SPT) and measurement of shellfish-specific IgE level. A SPT reaction spot that is 3mm or more in diameter and an IgE level of greater than or equal to 0.35 kUA/L which stands for kilo unit of allergen-specific IgE per litre, are commonly defined as a positive diagnosis of a shellfish allergy.</p>
<p>However, the rapidly growing number of diagnoses have highlighted concerning the <a href="https://www.ncbi.nlm.nih.gov/pubmed/21651567">shortcomings of these conventional procedures</a>. SPT and IgE measurement with shellfish extract have low specificity of only 50%, meaning that 50% of people with a positive result in these tests may never experience clinical symptoms of shellfish allergy.</p>
<figure>
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<figcaption><span class="caption">Skin prick tests are usually efficient to determine allergies but also present several shortcomings (Imperial College London).</span></figcaption>
</figure>
<p>Although reactions to all sorts of shellfish is common, <a href="https://www.ncbi.nlm.nih.gov/pubmed/18498545">reports</a> have suggested species-specific allergic reactions – for example, you may be able to eat one species of prawn even if you are allergic to another. However, because tests cannot identify cross-reactivity, patients are often suggested to avoid all types of shellfish if they have allergic reactions to one type of shellfish.</p>
<p>The oral food challenge, a test that involve giving increasing amounts of a food to a patient to determine if he or she has a food allergy, remains the gold standard. But it is resource-intensive, time-consuming, costly and risky. Subjects’ reluctance due to a fear of <a href="https://www.ncbi.nlm.nih.gov/pubmed/30298065">side effects</a> preclude the implementation of this procedure in clinical settings.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/261883/original/file-20190304-110134-1tnj447.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">If you’re allergic to mussels, you might not be allergic to clams. Tracking shellfish allergies need to take into consideration species-specific allergic reactions.</span>
<span class="attribution"><a class="source" href="https://pxhere.com/en/photo/493227">Pxhere</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Treatment could be improved</h2>
<p>“Active” treatment options that would desensitize shellfish-allergic patients are unfortunately not yet available. Patients are recommended to avoid shellfish that trigger symptoms, educated to read food labels to avoid accidental consumption, take antihistamines to alleviate mild symptoms, and use epinephrine auto-injector – a hand-held device that delivers epinephrine to relax the airways by intramuscular injection – in case of an anaphylactic reaction. However, none of these first-line measures cures the disease.</p>
<p>Food desensitisation and tolerance induction could be achieved by “re-educating” the immune system through giving small doses of the offending food and increasing it over time. However, existing interventions have reservations and limitations: the efficacy in developing tolerance is debatable; the adherence of patients is poor as the treatment is lengthy (2 to 5 years to “complete”); there are risks such as developing allergic side effects; and they’re costly, running between US$800 and $1,000 per year.</p>
<p>Our research team therefore focused our effort to address these shortcomings through investigating the value of <a href="https://www.ncbi.nlm.nih.gov/pubmed/26610061">peptide-based oral immunotherapy</a>, by which these peptides are short fragments of tropomyosin with molecular nature of modifying the immune system, and also by constructing hypoallergens of shrimp <a href="https://www.ncbi.nlm.nih.gov/pubmed/25365343">tropomyosin</a> and hypoallergen-based vaccines. Hypoallergens are modified from tropomyosin to be less than normally allergenic.</p>
<h2>Using a small DNA molecule to counter the allergy</h2>
<p>With the lower IgE reactivity, hypoallergens are of lower risk in triggering allergic reactions. We also adopted the concept of <a href="https://www.livescience.com/37247-dna.html">DNA</a> vaccination – the injection the DNA sequence of the hypoallergen in a small circular piece of bacterial DNA.</p>
<p>When taken up by body cells, this piece of circular DNA is used by the cells’ machinery to produce the hypoallergen protein. Because these proteins are regarded as foreign, the immune system is alerted to trigger immune response. The continual production of the hypoallergen protein by the vaccine and body cells therefore “educates” the immune system as in the conventional immunotherapy but achieved with fewer shots.</p>
<p>This combinatorial approach offers the advantages of improved vaccine stability, relative ease of large-scale manufacture, reduced shots and treatment duration, and thus a lower cost of immunotherapy.</p>
<figure>
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<figcaption><span class="caption">Dr. Wai explaining her hypoallergene-DNA vaccine project.</span></figcaption>
</figure>
<p>From our <a href="https://patents.google.com/patent/US20170107265A1/en">animal experiments</a> three shots of this hypoallergen-DNA vaccine resulted in the decrease of IgE level by 70%, accompanied by the increase in the number and activity of immune cells with regulatory functions. This suggests that this vaccine may be a valuable treatment for inducing immune tolerance against shellfish allergy achievable with much fewer injections and within shorter time period.</p>
<p>However, the only FDA-approved plasmid, pVAX1, has limited immunogenicity in human, meaning that DNA vaccines constructed using pVAX1 has limited capacity in provoking immune responses in the body of a human.</p>
<p>Engineering next-generation vaccines with optimised plasmids and studying their effects and mechanism would be our next steps, and we hope to provide a promising option in the future. Until then, be cautious with that lobster.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=121&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=121&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=121&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=152&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=152&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202296/original/file-20180117-53314-hzk3rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=152&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
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<p><em>Created in 2007 to help accelerate and share scientific knowledge on key societal issues, the AXA Research Fund has been supporting nearly 600 projects around the world conducted by researchers from 54 countries. To learn more about this author’s research, visit her <a href="https://www.axa-research.org/en/project/christine-yee-yan-wai">dedicated page</a> on the AXA Research Fund website.</em></p><img src="https://counter.theconversation.com/content/112143/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christine Wai receives funding from the Health and Medical Research Fund, HKSAR. </span></em></p>Alongside with milk, eggs, peanuts, tree nuts, wheat, soybeans and fish, shellfish are one of the eight allergens that account for 90% of food-related allergic reactions. What if a vaccine could exist?Christine Wai, Post-doctoral researcher, Axa research fund fellow, Chinese University of Hong KongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1038682019-01-28T15:06:03Z2019-01-28T15:06:03ZThe world’s shellfish are under threat as our oceans become more acidic<figure><img src="https://images.theconversation.com/files/255808/original/file-20190128-108370-1p0dgzp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fresh-oysters-seafood-557230198?src=jm6KWwOXZ4YNCPlmoRG_lQ-2-64">Shutterstock</a></span></figcaption></figure><p>For the past few million years the world’s oceans have existed in a slightly alkaline state, with an average <a href="https://www.britannica.com/science/pH%22%22">pH</a> of 8.2. Now, with <a href="https://www.nytimes.com/2018/03/22/climate/global-energy-demand.html">carbon emissions escalating</a>, there is more <a href="https://www.britannica.com/science/carbon-dioxide">CO₂</a> in the world’s atmosphere. This dissolves in the oceans, altering the chemistry of the seawater by lowering the pH and making it more acidic – up to <a href="https://ocean.si.edu/ocean-life/invertebrates/ocean-acidification">30% more</a> in the past 200 years. This growing <a href="https://nerc.ukri.org/planetearth/stories/265/">acidification</a> of the oceans is becoming a serious <a href="https://www.theguardian.com/environment/2017/oct/23/ocean-acidification-deadly-threat-to-marine-life-finds-eight-year-study">problem</a> for the production of shellfish around the world.</p>
<p>Shellfish are creatures which produce calcium carbonate shells and skeletons, such as mussels, oysters and corals. They create their protective shell structures through a process known as <a href="https://academic.oup.com/mbe/article/34/1/66/2670196">biomineralisation</a> – producing hard minerals such as <a href="https://www.britannica.com/animal/bivalve/The-shell#ref1074513">calcium carbonate</a> by filtering calcium and carbonate from the water. If the amount of carbonate available in the oceans is reduced by acidification, it limits the ability of these creatures to create shells.</p>
<p>But now <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.4416">coastal acidification</a> is happening close to land in regions where freshwater run-off can release <a href="https://www.environment.nsw.gov.au/topics/land-and-soil/soil-degradation/acid-sulfate-soils">sulphate soils</a> and excess carbon, which also lowers pH and carbonate available for producing shells. This is being exacerbated by flooding and rises in sea levels caused by climate change.</p>
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</figure>
<h2>A global problem</h2>
<p><a href="https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.4416">Recent studies</a> reported these implications for the <a href="https://www.sydneyfishmarket.com.au/seafood-school/seafood-info/species-info/species-details?specieID=202&fishID=97#.XE8JGM_7Su4">Sydney rock oyster</a> in New South Wales, Australia. <a href="https://bioone.org/journals/journal-of-shellfish-research/volume-28/issue-4/035.028.0409/The-Changing-Face-of-Oyster-Culture-in-New-South-Wales/10.2983/035.028.0409.short">Historically</a>, oyster production in the region has seen a decline in larger “plate-grade” oysters and an increase in smaller oysters. This can be due to a number of reasons which are physical, biological and economic, including pressures on farmers to harvest oysters early to avoid high winter mortalities in cold dry weather.</p>
<p>But our recent <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.4416">study</a> suggests that coastal acidification in Australia is damaging oysters’ ability to grow properly as well. The change in shell growth mechanisms could have implications for the future, such as producing thinner shells which are prone to fracture, causing potential risk of shell damage during culture and harvesting.</p>
<p>The situation in New South Wales is not an isolated case. In Washington state in the US, acidification caused by deeper, colder seawater with high levels of CO2 rising to the surface has caused malformations in oyster larvae and loss of hatchery seed production.</p>
<hr>
<p><em>Read more: <a href="https://theconversation.com/explainer-why-ocean-acidification-is-the-evil-twin-of-climate-change-2508">Explainer: why ocean acidification is the evil twin of climate change</a></em> </p>
<hr>
<p>A <a href="http://tos.org/oceanography/article/impacts-of-coastal-acidification-on-the-pacific-northwest-shellfish-industr">report</a> by one shellfish hatchery detailed the impact on shell formation in oyster larvae under these detrimental conditions. Oyster farms in Washington, have put measures in place to sustain oyster shellfisheries under increasingly acidic conditions. This includes treating hatchery water to increase pH, making more carbonate available for early larvae shell formation, and growing oyster seed in different locations to ensure their survival for future production. </p>
<p>In Scotland, a country famous for its high-quality shellfish, acidification is less of an imminent threat. There are no sulphate soils or deeper water with high levels of CO2 rising to the surface, as can be found in Australia and America. But as coastal acidification is made worse by climate change – in particular freshwater run-off from increased rainfall and sea-level rise – this could have a serious effect on commercial shellfisheries all over the world, including Scotland.</p>
<p>The changes in seawater chemistry associated with freshwater run-off include lowered salinity and pH, and carbonate availability. This, coupled with increasing temperatures, adds pressures to shellfish farmers producing mussels and oysters.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255811/original/file-20190128-108364-ey7rrs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An acidic seawater environment can produce thinner shells in oysters that can be more easily damaged in transit.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-placing-metal-bag-oysters-on-456531082">Shutterstock</a></span>
</figcaption>
</figure>
<p>I have previously <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsif.2014.1227">reported</a> on the effect of experimentally induced high CO2 acidification on mussels, where shells showed reduced growth and became more brittle. Shellfish are predicted to produce thinner shells which may also be more prone to fracture throughout harvesting, transportation or when another animal attempts to eat them.</p>
<h2>Breeding and resilience</h2>
<p>The industry needs to consider ways to reduce this risk. In Washington producers have adjusted the <a href="http://tos.org/oceanography/article/impacts-of-coastal-acidification-on-the-pacific-northwest-shellfish-industr">carbonate chemistry</a> in oyster hatcheries to develop larvae before release into farms where acidification has the potential to reduce early shell development.</p>
<p>In New South Wales, the <a href="https://www.dpi.nsw.gov.au/content/research/areas/aquaculture/outputs/2009/2070">Department of Primary Industries</a> has done studies on the Sydney rock oyster to examine the potential for selective breeding to develop resilient strains that can cope better with more acidic seawater conditions. Researchers have <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.13111">reported</a> on the potential for selective breeding for disease resistance and faster shell growth, which could create acidification resilience in the oyster.</p>
<p>Our next step working with Australia’s DPI is to examine these selectively bred oysters to understand the potential for combating the acidification problem. It is important for the Scottish shellfish industry to understand the risks posed by climate change already playing out in Australia and the US. With climate change in the future threatening freshwater and CO2-induced ocean acidification in UK waters, the country could suffer the same fate.</p><img src="https://counter.theconversation.com/content/103868/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Fitzer receives funding from the Natural Environment Research Council.</span></em></p>Acidic seawater conditions are interfering with the ability of shellfish to produce strong, resilient shells, and it’s happening all over the world.Susan Fitzer, Research fellow Environmental Management, Institute of Aquaculture, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1054792018-11-06T11:46:07Z2018-11-06T11:46:07ZHurricanes and water wars threaten the Gulf Coast’s new high-end oyster industry<figure><img src="https://images.theconversation.com/files/243967/original/file-20181105-74783-1ifvea0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Gulf Coast oysters on the half shell at Wintzell's, Mobile, Ala. </span> <span class="attribution"><a class="source" href="https://flic.kr/p/bofSen">donireewalker</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>For Cainnon Gregg, 2018 started out as a great year. After leaving his job as an installation artist to become a full-time oyster farmer in Wakulla County, Florida in 2017, Gregg began raising small oysters in baskets or bags suspended in the shallow, productive coastal waters of Apalachicola Bay. </p>
<p>Raising oysters “off-bottom” this way takes a lot of time and money, but has a big potential payoff. They are destined for the high-end raw bar market, where offerings are denoted by specific appellations, like “Salty Birds” (Cainnon’s oysters), “Navy Coves” (from Alabama) and “Murder Points” (also from Alabama), and can retail for twice the price of oysters harvested from traditional on-bottom reefs.</p>
<p>When Hurricane Michael made landfall at Mexico Beach, Florida, on Oct. 10, 2018, it dealt a devastating blow to this nascent industry. Preliminary reports indicate significant damage and heavy crop losses. Raising oysters by any method is not an easy job, but if off-bottom farming can become established along the Gulf Coast, it could give the industry a much-needed boost, give consumers more choices, and provide a new stream of environmental benefits.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BdXjq1PDEvP/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Premium products</h2>
<p>The United States produces multiple species of oysters, but historically the eastern oyster (<em>Crassostrea virginica</em>) has accounted for over 70 percent of total harvests. The Gulf Coast generally accounts for 80 percent of those, with production generating <a href="https://repository.library.noaa.gov/view/noaa/16121">US$1 billion in annual revenues</a>. </p>
<p>Louisiana is the national leader in oyster production, with a handful of other states vying for second place, including Washington, South Carolina and Texas. However, when states are ranked by value per unit – that is, total value over total landings – states like Massachusetts, Maryland and Virginia dominate.</p>
<p>This is partly due to regional differences in how oysters are grown and marketed. Traditional harvesting of oyster reefs on the sea bottom still dominates in the Gulf region. These oysters are generally sold as a commodity, appearing on menus as simply “oysters” or “Gulf Coast oysters.” </p>
<p>Elsewhere, most oysters come from off-bottom farming and tend to be marketed under the names of specific reefs, growers or appellations. Off-bottom oyster farming has been a <a href="https://www.fisheries.noaa.gov/national/aquaculture/us-aquaculture">major driver in the growth of marine aquaculture production nationally</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.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">Oysters are grown in cages at Island Creek Oyster Farm in Duxbury, Mass.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/bDGAqU">MA Office of Travel and Tourism/Hanks</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The Gulf’s first commercial off-bottom farms started up in Alabama and Louisiana in 2010. Today more than 50 farms are operating in Florida, Alabama and Louisiana, with permits pending for others in Mississippi. Harvest data are limited, but in Alabama alone, eleven farms collectively reported <a href="http://masgc.org/assets/uploads/publications/1312/alabama_shellfish_aquaculture_situation_and_outlook_report_2016.pdf">nearly $2 million in sales in 2016</a>. In recent years Alabama has ranked among the top five states in per-unit value.</p>
<h2>Reasons to diversify</h2>
<p>Raising off-bottom oysters is good for more than oystermen’s bottom lines. Oysters improve water clarity by filtering out phytoplankton, thereby removing nitrogen from the water column. They also provide forage grounds and habitat for fish and act as breakwaters, protecting nearby shorelines. </p>
<p>Off-bottom farms deliver the same types of benefits as traditional on-bottom reefs, although in slightly different ways and at different times, depending on local conditions and farming methods. In our view, raising oysters in multiple ways is beneficial because it avoids putting all of our eggs in one basket, so to speak, and makes the industry more resilient. </p>
<p>We come at this topic from different perspectives. <a href="https://scholar.google.com/citations?user=yPXqOj8AAAAJ&hl=en">Daniel Petrolia</a> focuses on the economics of <a href="http://dx.doi.org/10.3368/le.92.2.292">coastal resources</a> and <a href="http://dx.doi.org/10.3368/le.91.2.272">natural hazards</a>. <a href="https://scholar.google.com/citations?user=DzRuv-cAAAAJ&hl=en">William Walton</a> directs Auburn University’s <a href="https://mifralabgroup.wixsite.com/home">Marine Invertebrate Fisheries, Restoration and Aquaculture Lab</a>. We have worked together since 2011 to better understand <a href="https://restoreactscienceprogram.noaa.gov/projects/oyster-planning-tool">oyster habitats</a>, <a href="https://doi.org/10.1017/aae.2016.30">evaluate market opportunities</a> and identify and tackle challenges for the new industry. Disaster preparation and recovery clearly are top priorities.</p>
<p>We see off-bottom oyster farming as especially interesting economically, given its novelty on the Gulf Coast, the new market opportunities it affords growers and the diversity it brings to the Gulf Coast’s oyster habitat “portfolio.” It also offers new choices for people who like to eat Gulf Coast oysters.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9iPXluPr7V0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Marketing video from Panacea Oyster Co-Op in Wakulla County, Florida.</span></figcaption>
</figure>
<h2>Natural and man-made disasters</h2>
<p>Hurricanes and storms pose serious threats to the Gulf oyster industry. They can harm reefs by burying them in sediments or drastically altering water salinity. </p>
<p>Storm impacts tend to be highly localized. Prior to Hurricane Katrina in 2005, Mississippi was the fourth-largest oyster-producing state in the nation. Katrina <a href="https://www.st.nmfs.noaa.gov/commercial-fisheries/commercial-landings/annual-landings/index">slashed the state’s output by 80 percent that year</a>, and fishermen were unable to harvest oysters at all in 2006. Production recovered somewhat over the next several years, but Mississippi harvests have remained around one-tenth of pre-Katrina levels. </p>
<p>Louisiana, whose oyster reefs lie just west of where Katrina made landfall, saw just a 6 percent drop in production following Katrina. The impacts of the Deepwater Horizon disaster were shorter-lived, but Louisiana’s 2010 harvest was cut in half due to precautionary closures during and after the spill. Oysters were also killed by releases of fresh water from the Mississippi River, which were conducted in an effort to keep oil out of coastal estuaries.</p>
<p>Storms are not the only threat. Florida and Georgia have been fighting for decades over <a href="https://www.tampabay.com/news/environment/Supreme-Court-finally-rules-on-Florida-s-30-year-water-war-with-Georgia-And-it-s-not-over-_169506140">allocating water from the Apalachicola River</a>; when Georgia draws a high level of water, it reduces freshwater flow to Apalachicola Bay, which can lead to increases in oyster mortality from predation and disease. And harmful algal blooms, such as <a href="https://theconversation.com/what-is-causing-floridas-algae-crisis-5-questions-answered-101305">Florida’s massive 2018 red tide outbreak</a>, can close waters to harvesting.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1012001134343573505"}"></div></p>
<p>Beyond direct impacts on oyster farms, Hurricane Michael damaged state laboratories that conduct water quality testing required to re-open waters to harvesting. Testing delays could lead to prolonged closures and even affect areas not hit by the storm. Michael also disrupted red tide sampling in several Panhandle counties. In Gulf and Escambia counties, red tide concentrations actually <a href="http://myfwc.com/RedTideStatus">increased in late October</a>.</p>
<p>Farmers will be looking for more oyster seed – the small oysters that they need to restock their bags and baskets. This could drive up demand and strain the industry’s capacity. Unlike crop farmers on land, oyster farmers cannot buy subsidized insurance to help them with losses of oysters and gear, so those who suffered heavy damage will be challenged to rebuild their operations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=558&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=558&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=558&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=701&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=701&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=701&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hurricane Michael failed to break up the red tide outbreak along Florida’s west coast.</span>
<span class="attribution"><a class="source" href="http://myfwc.com/RedTideStatus">Florida Fish and Wildlife Conservation Commission</a></span>
</figcaption>
</figure>
<h2>Not an easy business</h2>
<p>As we write, oyster farmers in the Panhandle are still inspecting their farms for damage and seeing how their oysters fared. Some estimate that they may have lost <a href="https://www.nbcnews.com/news/us-news/hurricane-michael-may-have-dealt-deadly-blow-florida-s-nascent-n922356">60 to 90 percent of their crops</a>.</p>
<p>Oystermen have strategies for dealing with hurricanes, such as sinking baskets loaded with oysters to the bottom before the storm arrives. But they can only reduce risk, not eliminate it. The threat of <a href="https://tidesandcurrents.noaa.gov/publications/techrpt86_PaP_of_HTFlooding.pdf">rising sea levels</a> and <a href="https://opensky.ucar.edu/islandora/object/technotes:552">more intense storms</a> will force them to continue adapting and improving their strategies. </p>
<p>Earlier this year, Cainnon Gregg started selling “Salty Birds” to some of the finest oyster bars in the South. Two days after Hurricane Michael passed through, he was back on the water checking lines and making repairs. “There’s nothing easy about any of this, and all you can do is get back out here and get back to work,” he said. He could have been speaking for all Gulf oystermen.</p><img src="https://counter.theconversation.com/content/105479/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel R. Petrolia receives funding from the National Oceanic and Atmospheric Administration (NOAA), the Mississippi-Alabama Sea Grant Consortium, and the Bureau of Ocean Energy Management. </span></em></p><p class="fine-print"><em><span>William C. Walton receives funding from National Sea Grant, Mississippi-Alabama Sea Grant Consortium and the USDA. He is affiliated with Oyster South, a non-profit dedicated to advancing oyster aquaculture in the southern US.</span></em></p>Oysters are big business along the Gulf Coast, but raising them off-bottom – which yields a premium product – is just starting there. Hurricane Michael showed it won’t be easy.Daniel R. Petrolia, Professor of Agricultural Economics, Mississippi State UniversityWilliam C. Walton, Associate Professor of Fisheries Science, Auburn UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1018232018-10-11T19:07:39Z2018-10-11T19:07:39ZArchaeology can help us prepare for climates ahead – not just look back<figure><img src="https://images.theconversation.com/files/237680/original/file-20180924-7728-1ks7cm2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Remains of meals at Haua Fteah cave reveal a lot about past climates in in the Gebel Akhdar region of Libya. </span> <span class="attribution"><span class="source">Amy Prendergast </span>, <span class="license">Author provided</span></span></figcaption></figure><p><em>This article is part of our occasional long read series <a href="https://theconversation.com/au/topics/zoom-out-51632">Zoom Out</a>, where authors explore key ideas in science and technology in the broader context of society and humanity.</em></p>
<hr>
<p>Watching the weather for today and tomorrow is relatively easy with apps and news programs – but knowing what the climate was like in the past is a little more difficult. </p>
<p>Archaeological evidence can show us how humans coped with long-gone seasonal and environmental changes. For me, it’s fascinating because it reveals what life was like back then. But it’s useful beyond that too. This body of data helps us understand and build resilience to climate change in the modern world.</p>
<p>Archaeological data is now of a standard where it can map past climate variability, offer context for human-induced climate change, and even improve future climate predictions.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/friday-essay-how-archaeology-helped-save-the-franklin-river-92510">Friday essay: how archaeology helped save the Franklin River</a>
</strong>
</em>
</p>
<hr>
<h2>Surviving all the seasons</h2>
<p>As Earth takes its annual trip around the Sun, temperature, daylight hours and water availability vary through the <a href="https://www.youtube.com/watch?v=WgHmqv_-UbQ">seasons</a>. These dictate natural cycles of animal breeding and migration, and plant fruiting and flowering. Such cycles control the availability of food, shelter, and raw material resources.</p>
<p>People living in cities might notice the changing seasons: autumn leaves turn a golden hue, and in summer fresh berries fill the supermarket shelves. </p>
<p>However, modern technology and global trade networks lessen the impact of the seasons on our daily lives. We can buy strawberries at any time of year (if we pay a premium). We can escape summer heatwaves by turning on air conditioners. </p>
<p>In most parts of Australia, our lives no longer depend on tracking the changes in plants and animals throughout the year. But in the past, if you weren’t in tune with seasonal patterns, you wouldn’t survive.</p>
<p>In my work I study how past people interacted with seasonal changes, using evidence from archaeological sites around the world.</p>
<p>Past and present <a href="https://theconversation.com/early-birds-how-climate-change-is-shifting-time-for-animals-and-plants-34766">seasonal patterns</a> have changed due to climate change, causing <a href="https://www.sciencedirect.com/science/article/pii/S027737910500003X">cooler winters</a>, <a href="https://www.nature.com/articles/nclimate2468">warmer summers</a>, or altered <a href="https://www.nature.com/articles/nclimate2258">rainfall</a>. Different seasons may occur <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12755">earlier</a> or <a href="http://science.sciencemag.org/content/357/6351/588">later</a>, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12568">last longer</a> or be <a href="https://www.nature.com/articles/nclimate2468">more extreme</a>. </p>
<p>These changes have flow-on effects that can be detected in the archaeological record. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sustainable-shopping-want-to-eat-healthy-try-an-eco-friendly-diet-89086">Sustainable shopping: want to eat healthy? Try an eco-friendly diet</a>
</strong>
</em>
</p>
<hr>
<h2>Life in ancient Libya</h2>
<p>One archaeological site where seasonal changes have been well studied is the <a href="https://www.arch.cam.ac.uk/research/projects/haua-fteah-project">Haua Fteah</a> cave in the Gebel Akhdar region of Libya. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/237645/original/file-20180924-170656-1ffn8wx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The entrance to the Haua Fteah cave site, Libya.</span>
<span class="attribution"><span class="source">Giulio Lucarini, University of Cambridge</span></span>
</figcaption>
</figure>
<p>The Haua Fteah covers the transitions from prehistoric hunter-gatherers (beginning around <a href="https://www.sciencedirect.com/science/article/pii/S0047248417300283">150,000 years ago</a>), and prehistoric farmers (beginning around <a href="https://www.sciencedirect.com/science/article/pii/S0047248413002261">7,500 years ago</a>), right the way through to more recent times.</p>
<p>We found the Haua Fteah experienced the <a href="https://www.sciencedirect.com/science/article/pii/S0277379116300464">most arid</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0277379117308521">highly seasonal</a> conditions just after the last global ice age. This changed the plant and animal resources available in the local landscape over 17,000 to 15,000 years ago. </p>
<p>However, despite the climate and resource instability, human activity was the <a href="https://www.cambridge.org/core/journals/libyan-studies/article/cyrenaican-prehistory-project-2010-the-fourth-season-of-investigations-of-the-haua-fteah-cave-and-its-landscape-and-further-results-from-the-20072009-fieldwork/7A3C6CCC383AFB48FA66E16ADACDE28D">most intense</a> during this period.</p>
<p>To investigate this, we compared climate records from the Gebel Akhdar and adjacent regions of North Africa. </p>
<p>It turns out that even though the Gebel Akhdar had an arid and highly seasonal climate, it was <a href="https://www.sciencedirect.com/science/article/pii/S0277379116300464">not as arid</a> as surrounding regions at this time. Scientists believe that increasingly dry conditions elsewhere led to population increases at the Haua Fteah – people were simply seeking a less hostile place to live. </p>
<p>Additionally, use of <a href="https://www.sciencedirect.com/science/article/pii/S1040618215009039">shellfish as a food source</a> changed from a predominantly winter-focused activity to a year-round activity during this period. </p>
<p>Year-round shellfish reliance was probably an adaptation to supplement the diet when other resources were less available. A mixture of climate and population pressures likely drove the restriction of resources and reliance on shellfish.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-crab-and-prawn-shells-go-red-after-they-have-been-cooked-94297">Curious Kids: Why do crab and prawn shells go red after they have been cooked?</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/237643/original/file-20180924-117383-1o20zg5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Amy Prendergast excavating a shell rich layer from the archaeological site of Haua Fteah.</span>
<span class="attribution"><span class="source">Giulio Lucarini, University of Cambridge</span></span>
</figcaption>
</figure>
<p>But beyond just knowing what people ate, and when, hiding in such shells (and other items) are clues about regional differences in seasonality. </p>
<p>Here’s how it works.</p>
<h2>The remains of ancient meals</h2>
<p>Archaeologists are essentially trash sifters. We use clues preserved in artefacts, plant and animal remains that people threw away or left behind to reconstruct the past. </p>
<p>Hard animal parts, including <a href="https://www.sciencedirect.com/science/article/pii/S0305440315000412">mollusc shells</a>, <a href="https://www.sciencedirect.com/science/article/pii/S1040618215009684">teeth</a>, fish ear bones (<a href="https://theconversation.com/how-were-using-fish-ear-bones-as-time-capsules-of-past-river-health-95369">otoliths</a>) and <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/rcm.7670">antlers</a>, are routinely preserved in archaeological sites. These items accumulate from hunting, fishing, farming, and foraging activities. </p>
<p>The growth of these animal parts over time forms periodic growth rings, or increments. Much like tree rings in <a href="https://www.environmentalscience.org/dendrochronology-tree-rings-tell-us">dendrochronology</a>, the structure and chemical composition of these increments is influenced by the <a href="https://www.sciencedirect.com/science/article/pii/S0277379115301888">environment</a>. By analysing these increments, we can understand what the environmental conditions during the animal’s life may have been like.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-bling-makes-us-human-101094">How 'bling' makes us human</a>
</strong>
</em>
</p>
<hr>
<p>Seasonal variations in climate parameters such as <a href="https://www.sciencedirect.com/science/article/pii/S0031018217302614">temperature</a>, <a href="https://www.sciencedirect.com/science/article/pii/S0016703718303284">rainfall</a>, and <a href="https://www.sciencedirect.com/science/article/pii/S0277379117308521">humidity</a> can be reconstructed by analysing the chemical composition of these growth increments using the presence of <a href="https://www.sciencedirect.com/science/article/pii/S0031018217302614">stable isotopes</a> and <a href="https://www.sciencedirect.com/science/article/pii/S0012821X11003475">trace elements</a>.</p>
<p>Analyses of the annual — and in some cases, fortnightly, daily and even tidal — increments allow us to reconstruct a detailed timeline of environmental change. This field of study is known as <a href="https://www.sciencedirect.com/science/article/pii/S0031018217305862">sclerochronology</a> and it has expanded exponentially in the past couple of decades. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=359&fit=crop&dpr=1 600w, https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=359&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=359&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=451&fit=crop&dpr=1 754w, https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=451&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/233204/original/file-20180823-149484-cdhoo8.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">
<figcaption>
<span class="caption">Image of shell growth increments from a limpet shell. A shows where the shell is cut to reveal the cross section in B. The shell cross section in C has been stained to enhance the visibility of the increments.</span>
<span class="attribution"><span class="source">Amy Prendergast</span></span>
</figcaption>
</figure>
<p>The shells, teeth and animal bones that we analyse are the remains of food collected and consumed by people. Therefore climate reconstructions from them can be directly linked to human activity. </p>
<p>We can establish the animal’s <a href="https://www.sciencedirect.com/science/article/pii/S1040618215009039">season of death</a> and season of exploitation by humans by examining the growth pattern or chemistry of the most recent growth increment. For example, we can use oxygen isotopes to reconstruct the <a href="https://www.sciencedirect.com/science/article/pii/S0031018217302614">sea surface temperature</a> when the animal died. A very cool temperature tells us that the animal was collected by humans during the winter. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/233209/original/file-20180823-149475-l17quo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Marine mollusc shells (<em>Phorcus turbinatus</em>) from the Haua Fteah archaeological site.</span>
<span class="attribution"><span class="source">Amy Prendergast</span></span>
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<p>My colleagues and I recently wrote a <a href="https://www.sciencedirect.com/science/article/pii/S2352409X18305315">review article</a> and edited a journal <a href="https://www.sciencedirect.com/science/article/pii/S2352409X18305315">special issue</a> highlighting some of the latest research using these methods. The studies – which included evidence from <a href="https://www.sciencedirect.com/science/article/pii/S2352409X17305862">prehistoric hunter-gatherers</a> in the Mediterranean to <a href="https://www.sciencedirect.com/science/article/pii/S2352409X1830097X">historic Inuit sites</a> in Canada – show how people dealt with seasonal variability in the past. </p>
<h2>Learning from the past</h2>
<p>Climate change is one of the most pressing issues in today’s world. </p>
<p>However, our understanding of how human-induced climate change fits into natural climate variability (pre-industrial) is limited by the instrumental record, which rarely extends beyond <a href="http://science.sciencemag.org/content/292/5517/662">a century or so</a>. </p>
<p>Proxy records of past climate variability — such as increments from animal teeth or mollusc shells — extend our understanding of long-term climate variability.</p>
<p>Such abundant archaeological evidence can fill in the gaps from climate records about seasonal and sub-seasonal variation.</p>
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Read more:
<a href="https://theconversation.com/rising-seas-will-displace-millions-of-people-and-australia-must-be-ready-101906">Rising seas will displace millions of people – and Australia must be ready</a>
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<p>We need the robust, quantitative, detailed data we are now getting from archaeological sites around the globe. It helps to <a href="http://www.ipcc.ch/report/ar5/wg1/">contextualise</a> current and future climate change, and to form <a href="https://www.frontiersin.org/articles/10.3389/fmars.2016.00176/full">baselines for environmental monitoring</a>. </p>
<p>Additionally, these climate records are useful for testing and refining global and regional <a href="https://www.clim-past.net/10/221/2014/cp-10-221-2014.pdf">climate models</a>. More accurate climate models give us a better understanding of the overall climate system, and an enhanced ability to predict future climate change. </p>
<p>Such data may help us build resilience to climate change in our modern world.</p>
<p>So next time you tuck into your shellfish dinner, or juicy steak, take a moment to reflect on all of the useful information preserved in the intricate hard parts these creatures leave behind.</p>
<p>Will archaeologists of the future study your discarded shells and bones?</p><img src="https://counter.theconversation.com/content/101823/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amy Prendergast previously received funding from the Alexander von Humboldt Foundation. She is currently employed by the University of Melbourne and receives funding from a McKenzie Fellowship.</span></em></p>Archaeologists are trash sifters. They use clues preserved in artefacts, plant and animal remains that people threw away or left behind to reconstruct the past.Amy Prendergast, Lecturer in Physical Geography, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/906972018-02-18T19:13:46Z2018-02-18T19:13:46ZThe surprising benefits of oysters (and no, it’s not what you’re thinking)<figure><img src="https://images.theconversation.com/files/204773/original/file-20180205-19918-f0cg36.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Oysters can do a lot more than they're given credit for.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Think of oysters, and what comes to mind? You’ll probably picture a plate of seafood with a generous squeeze of lemon, or you might think of oysters’ <a href="https://theconversation.com/mondays-medical-myth-eating-oysters-makes-you-randy-4588">reputation as an aphrodisiac</a>. But oysters have many talents beyond their famed gastronomic (and other) qualities.</p>
<p>Oysters also help coastal ecosystems in many different ways, from cleaning the water to sheltering other animals. Yet despite their usefulness, newly published research led by the Nature Conservancy shows that <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190914">more than 90% of Australia’s shellfish reefs have been lost since European settlement</a>. Unless they can be restored, we risk missing out on their many benefits.</p>
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Read more:
<a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">Huge restored reef aims to bring South Australia's oysters back from the brink</a>
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<p>Oysters are multi-talented marine warriors with an impressive bag of tricks up their calcareous sleeves. Their filter-feeding improves water quality and nutrient cycling. They provide safe haven for young fish and small invertebrates, reduce coastal erosion, and even soak up carbon. </p>
<p>To capture these hidden talents, restoration of Australia’s <a href="https://blogs.adelaide.edu.au/environment/2017/07/24/oyster-reef-restoration-series-history-of-australias-oyster-reefs/">once abundant oyster reefs</a> is on the national agenda, culminating in the <a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">Southern Hemisphere’s largest oyster reef restoration project</a>, currently underway in South Australia. The latest research in this area will be showcased this week at a <a href="https://www.shellfishrestoration.org.au/news-events/19th-international-conference-on-shellfish-restoration-shellfish-reef-restoration-network-meeting/">conference</a> in Adelaide.</p>
<h2>Living on the edge</h2>
<p>Life is tough for animals living on intertidal rocky shores, such as snails and crabs. These animals experience extreme temperature swings during low tide, and are vulnerable to marine predators during high tide. </p>
<p>But oysters can help, by providing shelter for small invertebrates, giving them refuge from both weather and predators. The convoluted shells of oysters cast shade and trap moisture during low tide. This <a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12757/full">buffers the extremities of climate that animals’ experience</a>, with temperatures up to 10°C cooler than adjacent habitat during hot days. </p>
<p>At the landscape scale, <a href="http://onlinelibrary.wiley.com/doi/10.1890/15-0651.1/full">oysters remove the influence that changes in climate over latitude have on invertebrate communities</a>. In dampening the extremities of climate that organisms experience, oysters can buy intertidal species some time to adapt to climate change.</p>
<p>Another major benefit of oysters comes from their feeding habits. Oysters are filter feeders that improve water clarity by drawing in particles from the water column and sending them to the seafloor. A single oyster is like a pool pump, filtering up to 100 litres of water a day. Multiply that by the millions of oysters on a reef, and they become the kidneys of the coast, capable of <a href="https://link.springer.com/article/10.1007/s12237-012-9559-y">filtering entire estuaries within a matter of days</a>. </p>
<p>Clearer waters let in more sunlight. Meanwhile, the deposition of oyster faeces creates a nutrient-rich seafloor. This combination allows seagrass to thrive, in turn encouraging species such as burrowing clams, worms and crabs, and ultimately underpinning the entire coastal food web.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/-B6VV5kYmxU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Oysters sheltering fish (video by Francisco Martinez Baena).</span></figcaption>
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<p>Furthermore, these sediments promote the growth of particular bacteria that <a href="http://onlinelibrary.wiley.com/doi/10.4319/lo.2002.47.5.1367/full">convert excess organic nitrogen into inert nitrogen gas</a>, thus preventing algal blooms that can harm other species. This process has been <a href="https://academic.oup.com/bioscience/article/62/10/900/238172">valued at more than US$4,000 per hectare per year</a>. </p>
<p>Oysters’ filter-feeding is so efficient that Swedish researchers have evaluated it as a <a href="http://onlinelibrary.wiley.com/doi/10.1002/9780470960967.ch8/summary">cost-effective alternative to wastewater treatment plants</a>. Across the Atlantic, the loss of oyster reefs in Chesapeake Bay, the largest estuary on North America’s east coast, transformed the ecosystem from clear waters teeming with fish, to a murky, algae-choked mess. </p>
<h2>Living defences</h2>
<p>Sea levels and storm surge erosion are on the rise. In response, we are fortifying our coasts with solid seawalls. But these merely deflect wave energy, potentially shifting the problem along the coast. </p>
<p>Living oyster reefs, in contrast, dissipate wave energy. And unlike seawalls, their <a href="https://www.nature.com/articles/nclimate2216?WT.feed_name=subjects_ecosystem-services">growth can outpace sea level rise</a>. Oyster reefs’ role as <a href="http://www.oceanwatch.org.au/community/current-programs/">natural breakwaters</a> could be particularly helpful in estuaries where high boat traffic intensifies shoreline erosion, such as Sydney Harbour. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.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>
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<span class="caption">Sydney Harbour’s rock oysters can play a protective role.</span>
<span class="attribution"><span class="source">Maria Vozzo</span></span>
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<p>In sheltered bays, Sydney rock oysters grow vertically, providing a haven for invertebrates looking for somewhere to live. On exposed shorelines with intense wave action, oysters grow more horizontally, reducing drag against wave action. These hardy flattened oysters also shelter invertebrates, most of which would be dislodged in the oysters absence.</p>
<p>Oysters’ inherent adaptability has long been appreciated by aquaculture managers. The New South Wales oyster industry, the state’s oldest and most valuable aquaculture industry, has <a href="http://archive.dpi.nsw.gov.au/content/science-and-research/science-news/fisheries/aquaculture/disease-resistant-oysters">selectively bred oysters for more than 25 years</a>, breeding the best oysters together en masse to promote traits such as fast growth and disease-resistance. </p>
<p>But new techniques allows the production of oysters with specific characteristics while avoiding inbreeding, by <a href="https://www.selectoysterco.com.au/family-breeding-program">mating individual parents with desired traits</a>. This precise breeding could allow researchers to tailor-make oysters to endure specific environmental conditions, offering a boost to the various restoration projects around the world.</p>
<p>The future is looking bright for oyster restoration in Australia. Following <a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">South Australia’s lead</a>, <a href="http://www.natureaustralia.org.au/our-work/oceans/restoring-shellfish-reefs/port-phillip-bay/">Victoria</a>, <a href="http://www.natureaustralia.org.au/our-work/oceans/putting-the-oyster-reefs-back-into-oyster-harbour/">Western Australia</a> and <a href="http://restorepumicestonepassage.org/">Queensland</a> are increasing their efforts to re-establish reefs where they once thrived. New South Wales, meanwhile, is <a href="http://www.worldharbourproject.org/workgroups/green-engineering/">using green engineering techniques to enhance oyster communities on seawalls</a>.</p>
<p>With luck, in years to come oysters will still be sharing their many talents with us, and with their fellow marine creatures.</p><img src="https://counter.theconversation.com/content/90697/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian McLeod receives research funding from the National Environmental Science Program Tropical Water Quality Hub and Marine Biodiversity Hub.</span></em></p><p class="fine-print"><em><span>Dominic McAfee, Maria Vozzo, and Vivian Cumbo 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>Oysters aren’t just good for a feed. They also give a vital boost to coastal ecosystems, which is why efforts are underway to restore Australia’s once-abundant oyster reefs to their former glory.Dominic McAfee, Postdoctoral researcher, marine ecology, University of AdelaideIan McLeod, Senior Research Scientist - Coastal Restoration, James Cook UniversityMaria Vozzo, PhD in Marine Ecology, Macquarie UniversityVivian Cumbo, Postdoctoral Research, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/889802017-12-14T11:07:59Z2017-12-14T11:07:59ZPutting algae and seaweed on the menu could help save our seafood<figure><img src="https://images.theconversation.com/files/199053/original/file-20171213-27593-sfv3nk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>If we have to feed <a href="https://www.un.org/development/desa/en/news/population/world-population-prospects-2017.html">9.8 billion people</a> by 2050, food from the ocean will have to play a major role. Ending hunger and malnutrition while meeting the demand for more meat and fish as the world grows richer will require <a href="http://www.fao.org/fileadmin/templates/wsfs/docs/expert_paper/How_to_Feed_the_World_in_2050.pdf">60% more food</a> by the middle of the century.</p>
<p>But <a href="https://www.theguardian.com/environment/2016/jul/07/global-fish-production-approaching-sustainable-limit-un-warns?CMP=share_btn_tw">around 90%</a> of the world’s fish stocks are already seriously depleted. Pollution and increasing levels of carbon dioxide (CO₂) in the atmosphere, which is making the oceans warmer and more acidic, are also a significant threat to marine life.</p>
<p>There is potential to increase ocean food production but, under these conditions, eating more of the species at the top of the food chain, such as tuna and salmon, is just not sustainable. As a <a href="https://www.sapea.info/wp-content/uploads/FFOFINALREPORT.pdf">recent EU report</a> highlighted, we should instead be looking at how we can harvest more smaller fish and shellfish, but also species that aren’t as widely eaten such as seaweed and other algae.</p>
<p>The oceans have absorbed <a href="https://cloudfront.escholarship.org/dist/prd/content/qt8r14828w/qt8r14828w.pdf">around one third</a> of the CO₂ emitted into the atmosphere since the Industrial Revolution. The absorbed CO₂ goes through a series of chemical reactions that form carbonic acid and <a href="https://theconversation.com/global-warmings-evil-twin-ocean-acidification-19017">lower the pH of the water</a>. These reactions also reduce the concentration of carbonate ions, which are vital for those creatures that grow external skeletons such as corals and shellfish.</p>
<p>The acid and the lack of carbonate mean these organisms <a href="https://phys.org/news/2016-02-ocean-acidification-coralline-algae-robust.html">form weaker skeletons</a> and have to use more energy to do so, leaving less energy for growth and reproduction. Consequently, they up smaller in size. Aside from the <a href="https://theconversation.com/mussel-power-how-ocean-acidification-is-changing-shells-54976">impact this has on shellfish</a>, several of the species affected, such as corals in the tropics or <a href="https://www.nature.com/articles/srep20572">coralline algae</a> in the waters around the UK, also play a key role in providing food and nursing grounds for fish. And less fish food leads to fewer fish for us to catch.</p>
<h2>Climate change is affecting food production</h2>
<p>The impact of ocean acidification <a href="http://ec.europa.eu/research/sam/pdf/topics/food_ocean_sapea_report.pdf">varies widely across the globe</a>. But it is already affecting marine food production, particularly of shellfish. For example, CO₂-rich water along the west coast of the US means more oysters in local hatcheries are dying when <a href="http://tos.org/oceanography/article/impacts-of-coastal-acidification-on-the-pacific-northwest-shellfish-industr">they are still larvae</a>.</p>
<p>Warmer seas due to climate change are also affecting food supplies. Some species are <a href="https://www.theguardian.com/environment/2017/jan/08/fish-ocean-warming-migration-sea">moving towards the poles</a> in search of cooler water, forcing fishermen into more northerly waters or leaving them without stocks altogether. Some fishing fleets in northern locations will find more fish available but many will see the amount of fish available to catch fall by between <a href="https://www.nature.com/news/nutrition-fall-in-fish-catch-threatens-human-health-1.20074">6% and 30% depending on the region</a>. The biggest impact will be on areas that are already the most dependent on fishing, such as <a href="https://link.springer.com/article/10.1007/s11160-013-9326-6">Southeast Asia and West Africa</a>. </p>
<p>One possible solution is to eat more smaller fish and shellfish such as mussels. Large fish need to eat smaller fish to grow. If we eat smaller fish instead then we remove a step from the food chain and reduce the amount of energy lost in the process. What’s more, it might become easier to farm these smaller fish because the algae, cyanobacteria and other plankton they eat could actually benefit from warmer waters and higher levels of CO₂ in the atmosphere. This is because they get their energy from <a href="http://www.open.edu/openlearn/science-maths-technology/across-the-sciences/sunlight-powered-food-key-life-on-earth">photosynthesis</a> and so <a href="https://www.ncbi.nlm.nih.gov/pubmed/19093090">use CO₂ like fuel</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/199054/original/file-20171213-27575-1vq58v9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Spirulina, the new seafood cocktail.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p>It might also be possible to take this a step further and add some of these organisms directly to our diet, giving us an abundant new source of food. Seaweed, for example, is a type of algae that has been eaten for centuries, but only <a href="http://www.fao.org/docrep/006/y4765e/y4765e04.htm">35 countries commercially harvest</a> it today. Spirulina cyanobacteria is already eaten as a food supplement and <a href="http://www.independent.co.uk/life-style/food-and-drink/first-algae-based-vegan-eggs-holland-and-barrett-caked-omlettes-scrambled-eggs-plant-based-a7543901.html">several companies</a> are trying to turn other forms of algae into a <a href="https://link.springer.com/article/10.1007/s10811-016-0974-5">human food source</a>.</p>
<p>Farming these organisms in the right way could even help counter some of the effects of climate change on the rest of the food chain. For example, growing more seaweed <a href="https://www.greenwave.org/">lowers the amount of CO2</a> in the surrounding water, reduces acidification, and improves the environment for oysters and other shellfish. Managing seaweed harvest correctly will also maintain the dissolved oxygen and nutrient levels in the water, contributing to the overall health of the ocean.</p>
<p>Making algae a common part of more people’s diets won’t be easy. We need to ensure that any new algae food products on our dinner plates have the needed nutritional value but are also attractive and safe to eat. But sticking with our traditional salmon and tuna diet isn’t sustainable. Expanding our seafood menus could be a vital way of keeping the ocean healthy while it supplies the food we need.</p><img src="https://counter.theconversation.com/content/88980/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pallavi Anand receives funding from the UK Ocean Acidification research programme of Natural Environment Research Council and the Cushman Foundation for Foraminiferal research. </span></em></p><p class="fine-print"><em><span>Daniela Schmidt receives funding from the Natural Environment Research Council of the UK and the Royal Society (UK)</span></em></p>The ocean is getting warmer and more acidic but changing our diet could help us cope.Pallavi Anand, Lecturer in Ocean Biogeochemistry, The Open UniversityDaniela Schmidt, Professor in Palaebiology, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/716812017-09-11T00:40:32Z2017-09-11T00:40:32ZA deadly herpes virus is threatening oysters around the world<figure><img src="https://images.theconversation.com/files/176279/original/file-20170629-16069-z9yweh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Colleen Burge counts oysters on an oyster aquaculture lease in California. </span> <span class="attribution"><a class="source" href="http://imet.umces.edu/cburge/?gallery=california-field-work-2015">Collin Closek</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Oysters, a delicacy eaten on most coastlines of the world, are a multi-billion-dollar industry. They also are intriguing to study from a health perspective. Oysters feed by filtering tiny plankton from the surrounding water, processing <a href="http://www.habitat.noaa.gov/abouthabitat/oysterreefs.html">up to 50 gallons</a> per oyster daily. In doing so, they improve water quality and make their ecosystems healthier. But the water that they grow in can be filled with disease-causing microorganisms that can affect both oysters and humans. </p>
<p>Today a deadly herpes virus, <a href="http://dx.doi.org/10.1099/vir.0.80382-0">Ostreid herpesvirus 1 (OsHV-1)</a>, is threatening Pacific oysters (<em>Crassostrea gigas</em>), the world’s most popular and valuable oyster species. It is almost certain to spread more widely in our globally connected world. </p>
<p>I know what you’re thinking: “Oysters get herpes??” Yes, and they can also can get sick from other types of pathogens and stresses. But you won’t contract this virus from eating an oyster, whether you enjoy them on the half-shell or cooked. OsHV-1 can infect other bivalve species, like some animal herpes viruses that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2815145/">can cross species barriers</a>, but it is genetically distinct from other animal herpes viruses and does not infect humans.</p>
<p>With support from the <a href="http://seagrant.noaa.gov/WhatWeDo/CurrentFocusAreas/SustainableFisheriesandAquaculture.aspx">NOAA Sea Grant aquaculture program</a>, I’m working with a diverse team that includes researchers, regulators and outreach specialists in the United States and abroad to better prepare the U.S. oyster industry for the spread of this virus.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.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">Dead Pacific oyster sampled during a OsHV-1 mortality event this summer in Tomales Bay, California.</span>
<span class="attribution"><span class="source">Colleen Burge</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Deadly and spreading</h2>
<p>Pacific oysters are native to Asia and are the most popular and valued oyster for aquaculture globally. Humans transferred them from their native range to multiple grow-out areas <a href="http://www.fao.org/fishery/culturedspecies/Crassostrea_gigas/en">globally</a>, including France, the United States and Australia. They are the primary species grown on the U.S. West Coast, whereas both wild and cultured Eastern oysters grow on the East and Gulf coasts. In contrast to Eastern oysters, Pacific oysters were relatively resistant to infectious diseases until OsHV-1 emerged in the early 1990s. </p>
<p>Herpes is often fatal to Pacific oysters. That’s especially true for OsHV-1 microvariants – mutant variants of OsHV-1 which are more virulent than the original reference strain. These viruses are <a href="http://dx.doi.org/10.1098/rstb.2015.0213">spreading globally</a>, causing mass mortalities of Pacific oysters. </p>
<p>An OsHV-1 microvariant was first detected in France in 2008, where it <a href="http://dx.doi.org/10.1016/j.virusres.2010.07.011">killed 80 to 100 percent</a> of affected oyster beds. Since then, similar variants have caused mass mortalities of oysters in many <a href="https://doi.org/10.1007/s10499-015-9919-2">European countries</a>. A 2010 outbreak in England killed <a href="https://www.theguardian.com/environment/2010/jul/23/virus-kent-oysters">over eight million oysters</a>.</p>
<p>OsHV-1 microvariants also infect Pacific oysters in New Zealand and Australia. Their spread in Australia, in particular to Tasmania, has <a href="http://www.abc.net.au/news/2016-02-12/the-human-toll-behind-a-deadly-oyster-disease/7164712">crippled the Australian Pacific oyster aquaculture industry</a>. </p>
<h2>Resistance is the best defense</h2>
<p>U.S. oyster growers are strongly concerned about the spread of OsHV-1 microvariants globally. I was part of the team that first detected OsHV-1 in <a href="http://www.int-res.com/articles/dao2005/63/d063p033.pdf">Tomales Bay, California</a>. To date the virus has been detected only in oysters in Tomales Bay and an adjacent bay, and no microvariants have been found yet in U.S. waters. The California OsHV-1 <a href="http://www.int-res.com/articles/dao2006/72/d072p031.pdf">causes mortalities of young Pacific oysters</a>, but is thought to be less virulent than OsHV-1 microvariants.</p>
<p>Given the spread of the OsHV-1 microvariants elsewhere around the world, it may only be a matter of time until they reach U.S. coastal bays or other nonimpacted oyster growing areas. We spent the summer of 2017 conducting experiments in Tomales Bay to determine whether any cultured U.S. oysters species are resistant to OsHV-1, and soon will also conduct laboratory challenges with OsHV-1 microvariants. </p>
<p>Once OsHV-1 is established within a bay, mass oyster deaths typically occur each year during the summer when water temperatures are warm. The situation is analogous to a human who is infected with herpes and periodically get cold sores. Normally the virus is latent (present at a low level) and does not cause cold sores. But after a stressful situation, the virus replicates and cold sores emerge. </p>
<p>Not all oysters die of herpes, and if OsHV-1 behaves like other herpes viruses, it probably remains present latently within infected oysters’ tissues and is reactivated after a stressful event. For oysters, most of the evidence for virus reactivation points to warm summer water conditions.</p>
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<figcaption><span class="caption">Genetic improvements through breeding can improve Pacific oyster survival rates against the OsHV-1 virus.</span></figcaption>
</figure>
<h2>Cultivating oyster resistance</h2>
<p>We can’t vaccinate oysters, and even if antibiotics were effective against viruses, they are not permitted for treating oysters in the United States. Though oysters have an innate immune system that destroys foreign invaders, it lacks an adaptive response, including cells that “remember,” recognize and destroy specific pathogens, as human B or T lymphocytes do. Most vaccines rely on this “immune memory” to be effective. Recent research indicates that oysters’ innate immune systems <a href="https://doi.org/10.1016/j.molimm.2016.09.002">can be stimulated by a virus mimic</a>, but we do not know whether this effect is long-lasting. </p>
<p>The most effective strategy to date has been developing <a href="https://doi.org/10.1016/j.jip.2015.05.010">disease-resistant oyster lines</a>, which can limit both mortalities and oysters’ susceptibility to infection. But this approach involves exposing healthy oysters to the virus – and moving oysters infected with OsHV-1 to naive (disease-free) areas could spread the virus. This means that we can use this approach only in places where OsHV-1 already exists.</p>
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<figcaption>
<span class="caption">Pacific oyster seed ready for planting in Tomales Bay, California.</span>
<span class="attribution"><span class="source">Colleen Burge</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Toward that end, breeding programs in locations including France, New Zealand and Australia are working to develop OsHV-1-resistant Pacific oysters. A complementary approach is to expose oysters and determine genes involved in OsHV-1 resistance. I am currently working with two strains of OsHV-1 – the California virus and a microvariant in France – to determine OsHV-1 resistance genes, including a collaboration with the <a href="https://wwz.ifremer.fr/en/">Ifremer</a> station in La Tremblade, France.</p>
<p>The most effective way to limit damage in new locations from OsHV-1 is to limit its spread. However, we also want to be ready in case OsHV-1 microvariants spread to the United States. Beyond their cash value and the benefits that oysters provide by filtering water, <a href="http://www.habitat.noaa.gov/pdf/value_of_oysters.pdf">oyster reefs provide food and habitat</a> for many commercial fish species. Oysters can’t move themselves out of harm’s way, nor can we move all susceptible oysters, so we need to protect them where they grow.</p><img src="https://counter.theconversation.com/content/71681/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Colleen Burge is currently funded by the NOAA Sea Grant Aquaculture Program and the UMBC-UMB Research and Innovation Partnership Grant Program for her work on OsHV-1. She has been funded in the past by California Sea Grant College Program and National Sea Grant.</span></em></p>Oysters grow in seawater and filter their food from it, so how do you shield them from waterborne diseases? Scientists are working to develop strains that are resistant to a fast-spreading herpes virus.Colleen Burge, Assistant Professor, Institute of Marine and Environmental Technology, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/826802017-09-06T00:15:22Z2017-09-06T00:15:22ZHow a tiny portion of the world’s oceans could help meet global seafood demand<figure><img src="https://images.theconversation.com/files/184375/original/file-20170901-27284-18i667.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pike Place Market, Seattle.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/aauT4r">Doug Kerr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Seafood is an essential staple in the diets of people around the world. Global consumption of fish and shellfish has <a href="http://www.fao.org/3/a-i5555e.pdf">more than doubled over the last 50 years</a>, and is expected to keep rising with global population growth. Many people assume that most seafood is something that we catch in the wild with lines, trawls and traps. In fact, aquaculture (aquatic farming) accounts for just over half of all the seafood <a href="http://www.nmfs.noaa.gov/aquaculture/faqs/faq_aq_101.html">consumed worldwide</a>.</p>
<p>Today aquaculture is the fastest-growing food sector in the world. Most farmed seafood is currently produced in freshwater environments such as ponds, land-based tanks and <a href="http://worldwideaquaculture.com/quick-easy-fish-farming-the-raceway-aquaculture-system/">raceways</a>, but some producers are expanding to the open ocean.</p>
<p>Aquaculture <a href="http://www.fao.org/docrep/field/009/ag158e/AG158E02.htm">dates back thousands of years</a>, but has only recently become an essential part of our global food system. However, most of the world’s wild fisheries are <a href="http://www.fao.org/news/story/en/item/231522/icode/">already fished at their maximum sustainable yield</a>, so aquaculture will have to be the primary source of our seafood now and into the future. </p>
<p>This means that we need to understand how to farm fish and shellfish sustainably. We do not have broad-scale understanding today about the ecological limits and potential of cultivating seafood in the oceans. As a first step, we recently published a <a href="http://dx.doi.org/10.1038/s41559-017-0257-9">study</a> that estimated the offshore potential for aquaculture in marine waters, based on the growth performance of 180 farmed fish and shellfish species. We calculated that marine aquaculture could produce as much seafood as all of the world’s wild marine fisheries, using less than 0.015 percent of the space in the world’s oceans.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/vuRZNLGZ2zw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Open-ocean fish farming is a new industry with potential to grow along many of the world’s coastlines.</span></figcaption>
</figure>
<h2>Conflicting views of ocean aquaculture</h2>
<p>Total global wild catches have remained relatively unchanged for the past two decades. In 2015, <a href="http://www.fao.org/3/a-i5555e.pdf">92 million tons of wild species were harvested worldwide</a> – the same amount as in 1995. In contrast, seafood production from aquaculture increased from 24 million tons to 77 million tons during the same time period, and is still rising to help meet growing demand. In fact, it’s estimated that the world will need around <a href="http://www.nmfs.noaa.gov/aquaculture/faqs/faq_aq_101.html">40 million more tons of seafood as soon as 2030</a>.</p>
<p>Like all food production, aquaculture affects the environment and can be done in ways that are more or less sustainable. We want our science to help avoid destructive forms of aquaculture, such as <a href="http://dx.doi.org/10.1007/s002670010212">converting mangrove forests into shrimp farms</a>, and support more sustainable production. When it is done properly, aquaculture can be an <a href="https://www.wri.org/resources/data-visualizations/protein-scorecard">efficient farming method with reduced impacts</a>, compared to other types of protein such as <a href="http://www.nationalgeographic.com/foodfeatures/aquaculture/">beef, pork and even chicken</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"897992447409573888"}"></div></p>
<p>Interestingly, some of our previous research shows that people in developed countries such as the United States – the world’s <a href="http://www.fao.org/3/a-i5555e.pdf">second-largest seafood consuming country</a>, after China – tend to have <a href="https://doi.org/10.1371/journal.pone.0169281">more negative sentiment towards aquaculture</a> than people in developing countries. This is especially true for <a href="https://doi.org/10.3389/fmars.2017.00154">offshore aquaculture</a> in the open ocean. </p>
<p>The main concerns that we found did not focus on any particular species or impact. Rather, people were more worried about broad impacts on the environment and fishing. Just as unchecked fishing practices can damage ecosystems and wildlife, poorly sited and improperly managed fish farms can <a href="https://www.seafoodwatch.org/ocean-issues/aquaculture/pollution-and-disease">produce significant quantities of pollution and have the potential to spread diseases to wild species</a>.</p>
<p>However, not all aquaculture is created equal, and many of these issues can be addressed through good siting and oversight of offshore farming. Several studies have shown that siting fish and shellfish farms more than one nautical mile offshore, where water is deeper and currents are faster, can significantly <a href="https://doi.org/10.3389/fmars.2017.00154">reduce pollution and improve the condition of farmed species</a> when compared to nearshore production of the same species in the same region.</p>
<h2>Using big data to map aquaculture’s global potential</h2>
<p>Our recent <a href="http://dx.doi.org/10.1038/s41559-017-0257-9">study</a> used publicly available open source data and previous physiological and growth research to model and map the potential of aquaculture in the oceans for fish and bivalves, such as oysters and mussels. In addition to accounting for the biological limits of each species, we avoided areas of the ocean that are used for shipping and oil extraction, as well as <a href="https://theconversation.com/momentum-grows-for-ocean-preserves-how-well-do-they-work-65625">marine protected areas</a>. We also avoided depths greater than 200 meters, as a proxy for the limitations of cost and <a href="https://www.seafoodsource.com/news/aquaculture/7-cutting-edge-offshore-aquaculture-innovations-and-designs">current farm technology</a>.</p>
<p>After two years of analysis by our <a href="http://snappartnership.net/groups/sustainable-open-ocean-aquaculture/">expert working group</a>, we found that 3 percent of the world’s oceans appears very suitable for marine aquaculture. This may sound small, but it is actually an extraordinary amount of area, spread across nearly every coastal country in the world – about four million square miles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/184767/original/file-20170905-25593-irieqs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global hotspots for finfish aquaculture.</span>
<span class="attribution"><span class="source">Adapted from Gentry et al., Nature Ecology & Evolution 1, 1317–1324 (2017).</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Moreover, we don’t even need to use that entire area to meet world seafood demand. If aquaculture were developed in only the most productive areas, the oceans could theoretically produce the same amount of seafood that is currently caught by all of the world’s wild-caught fisheries, using less than 0.015 percent of the total ocean surface – a combined area the size of Lake Michigan. This is possible because many aquatic species can be farmed very efficiently, and because farming in the oceans can spread in three dimensions, across the surface of the ocean and downward below the waves.</p>
<p>From a conservation perspective, this means there is tremendous flexibility in where we can develop aquatic farms sustainably. And there is plenty of space in the oceans to produce huge amounts of food, while still <a href="http://dx.doi.org/10.1111/conl.12247">protecting vast areas</a>.</p>
<p>Our findings are also encouraging for global development. Many regions that are likely to contend with high population growth and food insecurity, such as India, the Middle East and Pacific island nations, show particularly high potential for marine aquaculture, which suggests that we can produce food where it is most needed.</p>
<p>Even so, expanding sustainable marine aquaculture will depend on creating economic and regulatory policies that help the industry grow while also protecting the health of the marine environment and the local communities that depend on it.</p>
<h2>A case for ocean optimism</h2>
<p>Our study has provided some of the initial science for exploring sustainable marine aquaculture’s role in the future of food production, while also considering key conservation goals on land and in the water. To expand on this work, we recently founded the <a href="http://www.cart-sci.org/">Conservation Aquaculture Research Team (CART)</a> at the University of California, Santa Barbara’s <a href="https://www.nceas.ucsb.edu/">National Center for Ecological Analysis and Synthesis</a>. Our future work will explore how climate change could impact aquaculture, and how aquaculture may impact people and nature compared to other food production systems.</p>
<p>We know that aquaculture will grow in the coming decades, but where and how this growth will happen depends on good governance, sustainable investment and rock-solid science. We hope to help guide aquaculture’s growth in a way that will feed a hungry world while also protecting our oceans.</p><img src="https://counter.theconversation.com/content/82680/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Halley Froehlich receives funding from the Science for Nature and People Partnership (SNAPP)</span></em></p><p class="fine-print"><em><span>Rebecca Gentry has received funding from SeaGrant and the Waitt Foundation</span></em></p>A new study shows that sustainable fish farming in deep ocean waters could produce as much seafood as all of the world’s wild fisheries, in a space the size of Lake Michigan or Africa’s Lake Victoria.Halley Froehlich, Postdoctoral Scholar, National Center for Ecological Analysis and Synthesis, University of California, Santa BarbaraRebecca Gentry, Ph.D. Candidate, University of California, Santa BarbaraLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/774052017-06-27T20:06:50Z2017-06-27T20:06:50ZHuge restored reef aims to bring South Australia’s oysters back from the brink<figure><img src="https://images.theconversation.com/files/172759/original/file-20170607-29563-agdn8h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mud oysters played a largely unappreciated part in Australia's history.</span> <span class="attribution"><span class="source">Cayne Layton</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The largest oyster reef restoration project outside the United States is underway in the coastal waters of Gulf St Vincent, near Ardrossan in South Australia. Construction began earlier this month. Some 18,000 tonnes of limestone and 7 million baby oysters are set to provide the initial foundations for a 20-hectare reef. </p>
<p>The A$4.2-million project will be built in two phases and should be complete by December 2018. The first phase is the 4-hectare trial currently being built by <a href="http://www.pir.sa.gov.au/">Primary Industries and Regions South Australia</a>; the second phase will see the reef expand to 20 hectares, led by <a href="http://www.natureaustralia.org.au/">The Nature Conservancy</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the 18,000 tonnes of limestone destined for the seafloor.</span>
<span class="attribution"><span class="source">D. McAfee</span></span>
</figcaption>
</figure>
<p>Just 200 years ago the native mud oyster, <em>Ostrea angasi</em>, formed extensive reefs in the Gulf, along more than 1,500km of South Australia’s coastline. Today there are no substantial accumulations of mud oysters anywhere around mainland Australia, with just <a href="http://www.abc.net.au/news/rural/2016-01-06/angasi-oyster-reef-research-restoration/7068628">one healthy reef remaining in Tasmania</a>. </p>
<p>This restoration project aims to pull our native mud oyster back from the brink of extinction in the wild, and restore a forgotten ecosystem that once teemed with marine life.</p>
<h2>More than just seafood</h2>
<p>Oysters played a large role in Australia’s colonial history. When European settlers first arrived they had to navigate a patchwork of oyster reefs (also called <a href="https://www.shellfishrestoration.org.au/">shellfish reefs</a>) that filled the shallow waters of our temperate bays. These enormous structures could cover 10 hectares in a single patch, providing an easily exploited food resource for the struggling early settlers. Oyster shell was burned to produce lime, and the colony’s first buildings were built with the help of oyster cement. </p>
<p>Collectively, these pre-colonial oyster reefs would have rivalled the geographic extent of the Great Barrier Reef, covering thousands of kilometres of Australia’s eastern and southern coastlines.</p>
<p>The history goes back much further too. For thousands of years oyster reefs fed and fuelled trade among Aboriginal communities. Shell middens <a href="http://www.tandfonline.com/doi/abs/10.1080/08920750601169618">dating back 2,000 years</a> attest to the cultural importance of oysters for coastal communities, who ate them in abundance and used their shells to fashion fishhooks and cutting tools. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.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">Health oyster reef in Tasmania.</span>
<span class="attribution"><span class="source">C. Gillies</span></span>
</figcaption>
</figure>
<p>The insatiable appetite of the newly settled Europeans for this bountiful resource was devastating. Not only were live oysters harvested for food, but the dead shell foundations that are critical for the settlement of new oysters were scraped from the seabed for lime burning. Armed with bottom-dredges a wave of exploitation spread across the coast, first overexploiting oyster reefs <a href="http://www.pnas.org/content/101/35/13096.short">close to major urban centres and then further afield</a>. The combination of the lost hard shell bed and increased sediment runoff from the rapidly altered coastal landscape saw oyster populations crash within a century of colonisation.</p>
<p>Today oyster populations are at <a href="http://www.bioone.org/doi/abs/10.1525/bio.2011.61.2.5">less than 1% of their pre-colonial extent</a> in Australia. This is not a unique story – globally it is estimated that <a href="http://www.bioone.org/doi/abs/10.1525/bio.2011.61.2.5">85% of oyster habitat has been lost</a> in the past few centuries, making it one of the most exploited marine habitats in the world. </p>
<p>Today, across much of Australia’s east coast you will see <a href="http://onlinelibrary.wiley.com/doi/10.1890/15-0651/full">Sydney rock oysters</a> encrusting rocky shores, creating a thin veneer around the edge of our bays and estuaries. On the south coast you occasionally see a solitary mud oyster clinging to a jetty pylon. Many Australians don’t realise that this familiar sight represents a mere shadow of the incredible and <a href="http://onlinelibrary.wiley.com/doi/10.1111/cobi.12452/abstract">largely forgotten</a> ecosystems that oysters once supported.</p>
<p>Oysters are an <a href="https://academic.oup.com/bioscience/article/62/10/900/238172/Economic-Valuation-of-Ecosystem-Services-Provided">unsung ecological superhero</a>, with the capacity to increase marine biodiversity, clean coastal waters, enhance neighbouring seagrass, reduce coastal erosion, and even slow the rate of climate change. When oysters cement together, their aggregations form habitat for a great diversity of other invertebrates. A 25cm-square patch of oysters can host more than 1,000 individual invertebrates from a range of different biological groups, in turn providing a smorgasbord for fish. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.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">Restoration site, formerly covered with dense oyster habitat.</span>
<span class="attribution"><span class="source">D. McAfee</span></span>
</figcaption>
</figure>
<p>A solitary oyster can <a href="http://darc.cms.udel.edu/ibog/newellecobivalve2.pdf">filter about 100 litres of water a day</a>, which means that <em>en masse</em> they can function as the “kidneys” of our bays, filtering excess nutrients from the water and depositing them on the seafloor. In doing so, they encourage seagrass growth, while their physical structures help to <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022396">dissipate wave energy</a> and thus reduce the impact of storm surges. </p>
<p>As if all that weren’t enough, oysters are also a <a href="https://academic.oup.com/bioscience/article/62/10/900/238172/Economic-Valuation-of-Ecosystem-Services-Provided">carbon sink</a>, building calcium carbonate shells that are buried in the seafloor after death and eventually compacted to rock, thus helping to prevent carbon dioxide from cycling back into the atmosphere.</p>
<h2>Building it back</h2>
<p>Restoring oyster reefs has the potential to return these ecosystem services and increase the productivity of our coastal ecosystems. The Gulf of St Vincent project came about through an <a href="http://www.environment.sa.gov.au/goodliving/posts/2016/08/artificial-shellfish-reef">election promise by the South Australian Government to boost recreational fishing</a>. A collaboration between <a href="http://www.natureaustralia.org.au/our-work/oceans/restoring-shellfish-reefs/south-australian-reef-to-revive-the-gulf/">The Nature Conservancy</a>, <a href="https://yorke.sa.gov.au/">Yorke Penninsula Council</a> and the <a href="http://pir.sa.gov.au/fishing/community_engagement/habitat_enhancement">South Australian Government</a> will deliver the reef’s foundations, while my colleagues and I at the University of Adelaide are working to ensure that the restored oysters survive and thrive, and that the reef continues to grow.</p>
<p>Hopefully this is just the beginning for large-scale <a href="https://www.shellfishrestoration.org.au/">oyster restoration in Australia</a>, and the lessons learned from this project will guide more restoration projects to improve the health of our oceans. With other restoration projects also underway in <a href="http://www.natureaustralia.org.au/our-work/oceans/restoring-shellfish-reefs/port-phillip-bay/">Victoria</a> and <a href="http://www.natureaustralia.org.au/2016/12/oyster-reefs-back-to-oyster-harbour/">Western Australia</a>, the tide is hopefully turning for our once numerous oysters.</p><img src="https://counter.theconversation.com/content/77405/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sean Connell receives funding from The Ian Potter Foundation and Department of Environment Water and Natural Resources and The Environment Institute of The University of Adelaide for this research. </span></em></p><p class="fine-print"><em><span>Dominic McAfee 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>In colonial times Australia’s waters were teeming with mud oysters that provided food, cement, and cleaned the oceans. Now a 20-hectare man-made reef aims to restore some of their former glory.Dominic McAfee, Postdoctoral researcher, marine ecology, University of AdelaideSean Connell, Professor, Ecology, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/770192017-05-16T20:08:48Z2017-05-16T20:08:48ZCurious Kids: why are some shells smooth and some shells corrugated?<figure><img src="https://images.theconversation.com/files/167617/original/file-20170503-4124-13chwma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some sea animals with smooth shells can dig themselves into the sand in just a few seconds.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/jridgewayphotos/6960539216/in/photolist-bB5zNQ-c3wPQo-a8gPTP-nLuv5-ajgZVG-9tG9w-d15s2C-nNeWX4-bUngjy-aPbXi6-9rFv7u-84vo2x-hJjpg-c3wPRY-fFzvd3-GKJ2Q2-cS4cff-dGx2X6-boGvv-ghRgP-dD1Wo-SrixbQ-5V8VxX-9KQoeQ-5egrxX-pfz9CS-p7RCUV-98EHXP-85zuiA-4tZqpd-8kRxDW-64i19X-6k9viY-4vmznJ-9oetLM-91pakw-9WQ4NE-XPerM-pDvqhm-7fYUAr-b1ihVD-4nmsYZ-dQnXrZ-neTKRF-jUkAV-8JhL9Q-M3mKC-F9tLj-59tsiy-2VPJE">Flickr/jridgewayphotography</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p><em>This a piece from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a new series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky! Email your question to curiouskids@theconversation.edu.au</em> </p>
<hr>
<blockquote>
<p>Why are some shells smooth and why do others have a corrugated shell? <strong>– Maëlle, 7, Cebu City, Philippines.</strong></p>
</blockquote>
<p>What an interesting question! There are a few possible answers.</p>
<p>Squishy, soft-bodied animals like pipis, oysters, mussels and scallops live inside shells.</p>
<p>A lot of animals (including many humans) think these shellfish are pretty tasty, so they need shells to protect them from hunters who want to eat them. </p>
<p>Some fish can pick up the shell in their mouths and smash it open against a rock. Other animals, like octopuses and snails, can drill a hole into the shell and inject poison that can kill and digest the animal that lives inside.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/167615/original/file-20170503-4128-1w09bjp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Corrugated shells are strong, but smooth shells are fast. Not always fast enough, though – a hunter has drilled a hole in this little shell to suck the animal out.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/cluczkow/3498687815/in/photolist-6kaFZH-qJit7j-9ndQbz-4stCgH-7RW2V-gh1Es-4CEY7Y-6t9jP5-agptH-eZaTMZ-cDGwmN-9KoBs5-PjHcc-6KtG7D-4WkssB-cDxy2C-hZpcAV-4LK8S4-6JsPj7-dVGh3R-BEHiys-nD4zkU-pgNk7W-4beKGu-8UCCB-aDS9e-7UqpD2-6iC1Hp-wuWfk-z4Z7LZ-4RsNad-5WB6Gt-6K99cE-29RPeK-zPGBV-dYX8Rf-gTWTM-28z5qx-bTtKbx-2qDJvz-6zajC-6mMKNF-evHPwc-akdtDn-6h1iW7-9EUDc8-bqiAra-mowHH-j1PNn-DYQ6x">Flickr/Chris Luczkow</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>They then suck the digested animal out through the hole they drilled, much like you might suck up a drink through a straw. Having a strong shell may help protect the mollusc living in the shell from these kinds of attack.</p>
<p>It is possible that the corrugations may help strengthen these shells. Have you ever seen a corrugated iron roof on a house? Corrugating it strengthens the iron and makes the roof stronger. Scientists think perhaps that is also true for corrugated shells. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=537&fit=crop&dpr=1 754w, https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=537&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/167612/original/file-20170503-17251-zijzjs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=537&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Corrugation makes something stronger – that’s why humans often use corrugated iron for the roof of a house.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/mikecogh/7949449638/in/photolist-d7t1qw-n8CCP2-4xWxeu-oma5kW-8xedMu-6yk97y-bNcSRT-dRbrnh-aixJLM-8fB7SD-51jM6d-4Ktc2r-cCxWZL-dcbBxv-kkqLqV-DxQbYN-d7TWsb-iG95X8-nycMWJ-94ekBe-8WrZVh-6pZF2C-dQmZsq-6pZEXC-4nEwK7-arUhjm-fMTdfP-arUdoG-myns4n-fBtJm5-pbc1Vo-iSXuhm-jrccNQ-6nTCtt-7aBhHD-8vZaU6-oUcCid-7HFxdA-e8MMWi-dhZ3fo-EPHSFU-HWr8Rw-j9HmUr-nEeBv2-58Lky-4m5Y8B-58Lkx-83x9J3-eLQQLW-UbSfou">Flickr/Michael Coghlan</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Scallops have a fan-shaped corrugated shell which is hard to break, even if you drop it or hit it. These corrugations are called ribs and provide scallops with strong and rather heavy shells.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/167613/original/file-20170503-4135-189zkmx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Here are some scallop shells from the US.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/casgeology/5518353498/in/photolist-9pD1eQ-mHzj4-ouKe9G-qCpZs7-78NwJX-6bKM4h-aXZjLP-aXZjhR-DSPTro-Doz1Vn-8Mjf8o-8Mgbun-8Mgb8K-8Mgbse-NTjFY-8Mgbna-8MgbhF-jYrAe-3dUZN8-6kxE4D-5RQ5tQ-78yUip-8MgbDe-qRSvHs-buonRf-8MjeMs-b6VLQi-7rqgFs-nWDiHC-7xxrm9-88J1Sy-8r3Pw-9Hzeri-7SbmZe-3XqMnM-5nHPDS-3mRCMy-3ZJ1F-4YCXw1-2U7egX-aotZZ7-brcSBK-6kBPaf-6kBP5A-24FdDY-y6d9A-fxwXEn-MiTcg-81m9qt-LhXCi">Flickr/california academy of sciences geology.</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The corrugations may also help with camouflage. Other animals and plants can grow on their shells, making the scallops masters of disguise! But when camouflage does not work, scallops can <a href="http://www.bbc.co.uk/nature/life/Pectinidae#p00br2z8">swim in a clumsy way</a> by opening and closing their valves quickly.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/kw6wGwKEdT8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scallops can swim – they often look a bit funny when they do it!</span></figcaption>
</figure>
<p>Giant clams do not move or dig themselves into the sand. Their main strategy for protection is to grow super strong, thick and heavy shells and, as you can see, these also have corrugations. Giant clams are the largest clams in the world. They can reach up to 1.2 metres in length (around the height of a six-year-old kid!), weight more than 200 kilograms and can live for more than 100 years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/167504/original/file-20170502-17251-1ptomkl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A giant clam’s main strategy for protection is to grow super strong, thick and heavy shells. They must be doing something right because they can live for more than 100 years.</span>
<span class="attribution"><a class="source" href="http://www.joaoinacio.net">João Inacio</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The animals that have smooth shells use a different approach to protect themselves from other animals. They can move away quickly and dig themselves into the sand really fast! It is like sliding in the playground; having a smooth shell would make it easier for these animals to move more quickly, just like a smooth slide would let you go faster than a bumpy slide. </p>
<p>Look how fast this pipi can dig down!</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/HRj0a99ybcg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Pipis use their foot to dig down. Maybe their smooth shells help them go faster.</span></figcaption>
</figure>
<p>Clams with smooth shells (including pipis) can dig themselves into the sand in just a few seconds! They use their foot (which looks more like a tongue) for digging. And they use their long siphon to breathe when burrowed, much like you would use a snorkel to breathe when you are underwater. </p>
<p>This way, they are protected but are still able to feed and breathe.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/hsBVvlJjNtc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Dig, dig, dig.</span></figcaption>
</figure>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_KVFDfv6R2M?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Clams don’t have brains, but they can dig fast using their foot (which looks like a tongue).</span></figcaption>
</figure>
<p>Animals can use many different strategies to protect themselves. It is likely that many of these animals evolved to have different types of shells that are good – in different ways – at keeping the squishy animals inside safe and sound.</p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p class="fine-print"><em><span>Jan Strugnell receives funding from the Australian Research Council and the Fisheries Research and Development Corporation. </span></em></p><p class="fine-print"><em><span>Catarina Silva 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>Maëlle, 7, wants to know why some shells are smooth, while others are corrugated. It turns out that while corrugated shells are strong, smooth shells can move fast.Jan Strugnell, Associate Professor Marine Biology and Aquaculture, James Cook UniversityCatarina Silva, Postdoctoral Research Fellow, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.