tag:theconversation.com,2011:/uk/topics/coral-bleaching-3618/articlesCoral bleaching – The Conversation2024-03-09T08:43:31Ztag:theconversation.com,2011:article/2253482024-03-09T08:43:31Z2024-03-09T08:43:31ZThe Great Barrier Reef’s latest bout of bleaching is the fifth in eight summers – the corals now have almost no reprieve<p>For the fifth time in just the past eight summers – 2016, 2017, 2020, 2022 and now 2024 - huge swathes of the Great Barrier Reef are experiencing extreme heat stress that has triggered yet another <a href="https://www2.gbrmpa.gov.au/learn/reef-health/reef-health-updates">episode of mass coral bleaching</a>. </p>
<p>Including two earlier heating episodes – in 1998 (which was at the time the hottest year globally on record) and 2002 – this brings the tally to seven such extreme events in the past 26 years. </p>
<p>The most conspicuous impact of unusually high temperatures on tropical and subtropical reefs is wide-scale coral bleaching and death. Sharp spikes in temperature can destroy coral tissue directly even before bleaching unfolds. Consequently, if temperatures exceed 2°C above the normal summer maximum, heat-sensitive corals die very quickly. </p>
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<figcaption><span class="caption">Reef Health Update (8 March 2024) Great Barrier Reef Marine Park Authority.</span></figcaption>
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<h2>What is coral bleaching?</h2>
<p>Bleaching happens when marine heatwaves disrupt the relationship between corals and their “photosynthetic symbionts” – tiny organisms that live inside the corals’ tissues and help power their metabolism.</p>
<p>Severe bleaching is often fatal, whereas corals that are mildly bleached can slowly regain their symbionts and normal colour after the end of summer, and survive. </p>
<p>Before 1998, coral bleaching on the Great Barrier Reef was infrequent and localised. But over the past four decades, bleaching has increased in frequency, severity and sptial scale, as a result of <a href="https://www.science.org/doi/10.1126/science.aan8048">human-induced climate heating</a>.</p>
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Read more:
<a href="https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197">We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy</a>
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<p>“Mass coral bleaching” refers to bleaching that is severe and widespread, affecting reefs at a regional scale or even throughout the tropics triggered by rising global sea temperatures.</p>
<p>The Great Barrier Reef consists of more than 3,000 individual coral reefs. It’s the same size as Japan or Italy, and extends for 2,300km along the coast of Queensland. Widespread coral deaths during extreme heatwaves, affecting hundreds of millions of coral colonies, <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15805">far exceed the damage</a> typically caused by a severe cyclone.</p>
<h2>How bad is 2024?</h2>
<p>Heat stress this week is reaching record levels on large parts of the Great Barrier Reef. </p>
<p>Climate scientists can measure the accumulation of heat stress throughout the summer by using a metric called “<a href="https://www.pacioos.hawaii.edu/voyager/info/coral_bleaching_degree_heating_week.html">degree heating weeks</a>” (DHW), which factors in both the duration and intensity of extreme heat exposure. This measures how far the temperature is above the threshold that triggers mild bleaching (1°C hotter than the normal summer maximum), and how long it stays above that threshold.</p>
<p>The same DHW exposure can result either from a long, moderate heatwave or from a short, intense peak in temperatures. The 2023–24 summer has been a slow burner on the Great Barrier Reef – sea temperatures have not been as extreme as during previous bleaching events, but they have <a href="http://www.bom.gov.au/oceanography/oceantemp/sst-outlook-map.shtml">persisted for longer</a>.</p>
<p>As a general rule of thumb, 2–4 DHW units can trigger the onset of bleaching, and heat-sensitive species of coral begin to die at 6–8 DHW units. So far this summer, <a href="https://x.com/profterryhughes/status/1762293105175445921?s=12&t=jfoU3j0RiQtYeeHqbSpjlA">according to the US National Oceanographic and Atmospheric Administration</a>, heat stress on the Great Barrier Reef has climbed to 10–12 DHW units on many individual reefs, and has been north and south compared to the central region. Heat stress will likely peak in the next week or two at levels above all previous mass bleaching and mortality events since 1998, before falling as temperatures drop.</p>
<p>Coral bleaching is typically very patchy at the enormous scale of the Great Barrier Reef. In each of the previous events since 1998, <a href="https://www.cell.com/current-biology/pdfExtended/S0960-9822(21)01490-1">20–55% of individual reefs</a> experienced severe bleaching and coral deaths, whereas 14–48% of reefs were unharmed.</p>
<p>Given the near-record levels of heat stress this summer, we can expect heavy losses of corals to occur on hundreds of individual reefs over the next few months.</p>
<h2>What’s the longer-term outlook?</h2>
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<p>This latest, still-unfolding event was entirely predictable, as ocean temperatures continue to rise due to global heating. </p>
<p>Three of the seven mass bleaching events so far on the Great Barrier Reef coincided with El Niño conditions (1998, 2016 and this summer), and the remaining four did not. Increasingly, climate-driven coral bleaching and death is happening regardless of whether we are in an El Niño or La Niña phase. Average tropical sea surface temperatures are <a href="https://www.science.org/doi/10.1126/science.aan8048">already warmer today</a> under La Niña conditions than they were during El Niño events only three or four decades ago.</p>
<p>The Great Barrier Reef is now a chequerboard of reefs with different recent histories of coral bleaching. Reefs that bleached in 2017 or 2016 have had only five or six years to recover before being hit again this summer – assuming they escaped bleaching during the 2020 and 2022 episodes. </p>
<p>Clearly, the gap between consecutive heat extremes is shrinking – we are vanishingly unlikely to see another 14-year reprieve like 2002 to 2016 again in our lifetimes, until global temperatures stabilise.</p>
<p>Ironically, the corals that are now prevalent on many reefs are young colonies of fast-growing, heat-sensitive species of branching and table-shaped corals – analogous to the rapid recovery of flammable grasses after a forest fire. These species can restore coral cover quickly, but they also make the Great Barrier Reef more vulnerable to future heatwaves. </p>
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Read more:
<a href="https://theconversation.com/concern-for-the-great-barrier-reef-can-inspire-climate-action-but-the-way-we-talk-about-it-matters-216992">Concern for the Great Barrier Reef can inspire climate action - but the way we talk about it matters</a>
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<p>Attempts to restore depleted coral cover through coral gardening, assisted migration (by harvesting larvae) and assisted evolution (rearing corals in an aquarium) are prohibitively expensive and <a href="https://www.cell.com/one-earth/pdf/S2590-3322(23)00189-6.pdf">unworkable at any meaningful scale</a>. In Florida, coral nurseries <a href="https://thehill.com/homenews/ap/ap-u-s-news/ap-hot-seawater-killed-most-of-cultivated-coral-in-florida-keys-in-setback-for-restoration-effort/">suffered mass deaths</a> due to record sea temperatures last summer.</p>
<p>The only long-term way to protect corals on the Great Barrier Reef and elsewhere is to rapidly reduce global greenhouse emissions.</p><img src="https://counter.theconversation.com/content/225348/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Terry Hughes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Great Barrier Reef is facing its worst summer of sustained heat stress since the mass bleaching event of 1998, but now with less time to recover amid repeated brutal conditions.Terry Hughes, Distinguished Professor, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2232072024-02-22T03:21:11Z2024-02-22T03:21:11ZSentinels of the sea: ancient boulder corals are key to reef survival in a warmer world<figure><img src="https://images.theconversation.com/files/574821/original/file-20240212-20-avdzaz.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5568%2C3700&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Giacomo d Orlando </span></span></figcaption></figure><p>Seas surrounding Australia this month hit an <a href="https://coralreefwatch.noaa.gov/data_current/5km/v3.1_op/daily/png/ct5km_baa5-max-7d_v3.1_seel_current.png">alarming level</a> of warming. It comes on the back of serious <a href="https://research.noaa.gov/2023/06/28/global-ocean-roiled-by-marine-heatwaves-with-more-on-the-way/">marine heatwaves</a> in the Northern Hemisphere summer.</p>
<p>Such warming is <a href="https://floridakeys.noaa.gov/corals/climatethreat.html#:%7E:text=Rising%20(or%20even%20falling)%20water,the%20coral%20turns%20completely%20white.">highly dangerous</a> for corals. Every <a href="https://www.annualreviews.org/doi/pdf/10.1146/annurev-animal-021122-093315">half a degree</a> of ocean warming increases their risk of bleaching and potential death.</p>
<p>The best long-term strategy to protecting Earth’s coral reefs is to dramatically cut greenhouse gas emissions and so limit global warming. But in the meantime, we must urgently make corals more resilient and protect those that are vulnerable.</p>
<p>That is particularly true for the huge, ancient features of reefs known as boulder corals. Research suggests they will be a vital part of reef survival in a warmer world.</p>
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<img alt="A map of Australia surrounded by patches of yellow, red and purple" src="https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576928/original/file-20240221-26-asgzx0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&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">An image showing various levels of bleaching alert around Australia as of February 19, 2024.</span>
<span class="attribution"><span class="source">NOAA Coral Reef Watch</span></span>
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<h2>The old-growth trees of the sea</h2>
<p>Boulder corals (<em>Porites</em>) can grow to more than <a href="https://link.springer.com/referenceworkentry/10.1007/978-90-481-2639-2_273#:%7E:text=Porites%20has%20attracted%20the%20attention,10%20m%20(indeterminate%20growth).">10m high</a> and live for <a href="https://onlinelibrary.wiley.com/doi/10.1111/brv.12391">more than 600 years</a>. In Australia they are often referred to as “bommies”. Each bommie can comprise multiple species, but they’re often a single massive individual.</p>
<p>The corals <a href="https://www.sciencedirect.com/science/article/pii/S0169534716000574?via%3Dihub">play a crucial role</a> in reefs, including providing habitat for marine life. Importantly, they can <a href="https://www.pnas.org/doi/full/10.1073/pnas.1716643115">maintain these functions</a> even when other coral species are absent.</p>
<p><a href="https://www.nature.com/articles/s41598-019-40150-3">Some species</a> are thought to be <a href="https://www.int-res.com/articles/meps2011/434/m434p067.pdf">resistant to stress</a>. Old corals have <a href="https://www.nature.com/articles/s41558-018-0351-2">likely experienced</a>
– and survived – past warming episodes, proving <a href="https://www.science.org/doi/10.1126/sciadv.abq8349">their resilience</a>.</p>
<p>For example, a paper in 2021 described a giant boulder coral discovered on the Great Barrier Reef which <a href="https://www.nature.com/articles/s41598-021-94818-w">was thought to be</a> more than 400 years old. It has survived 80 major cyclones, numerous coral bleaching events and centuries of exposure to other threats.</p>
<p>This resilience can benefit the whole reef ecosystem. We can think of boulder corals as akin to old-growth trees in a forest. Just like forests containing big, old trees are <a href="https://theconversation.com/contrary-to-common-belief-some-forests-get-more-fire-resistant-with-age-95059">more resistent</a> <a href="https://www.jstor.org/stable/26267895#:%7E:text=The%20adaptations%20of%20large%20trees,to%20withstand%20and%20survive%20fire.">to fire</a>, studies show a mix of different growth forms, including old and large boulder corals, <a href="https://www.nature.com/articles/s41558-021-01037-2">fare better</a> in the long-term under marine warming. </p>
<p>Older and bigger corals may also produce <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1002/ecy.1588?casa_token=tFnyWSTHmk0AAAAA:RkR06I_gTJk6p3vOCCdJdwku2CXO5tpUsChBn5_Nmhxfojl11fVg4uibQsWM4JFigd3dXzUYl_H8">more offspring</a>, so can more rapidly replenish the reef after disturbances.</p>
<p>Clearly, as our oceans face unprecedented pressures under climate change, we must protect – and learn from – these sentinels of the sea.</p>
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Read more:
<a href="https://theconversation.com/snorkellers-discover-rare-giant-400-year-old-coral-one-of-the-oldest-on-the-great-barrier-reef-166278">Snorkellers discover rare, giant 400-year-old coral – one of the oldest on the Great Barrier Reef</a>
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<h2>Preparing for the challenges ahead</h2>
<p>Understanding boulder corals is crucial to predicting how they might cope under climate change, and planning for their protection.</p>
<p>But scientists still have much to learn about boulder corals. In particular, we <a href="https://www.nature.com/articles/s41559-023-02319-y">don’t know</a> exactly how many species exist, their life histories and how they evolved. </p>
<p>My colleagues and I are aiming to overcome this knowledge gap. We are studying reefs across Australia, with a particular focus on boulder corals at Ningaloo Reef off Western Australia.</p>
<p>We are creating maps of what species of boulder corals exist and where they are located. And using cutting-edge <a href="https://threatenedspeciesinitiative.com/">genomics technology</a>, such as DNA sequencing, we are measuring the tolerance of each species to warming and trying to predict when they will reproduce. </p>
<p>Importantly, we are also examining the mutually beneficial relationship between the corals and algae. This relationship provides algae with shelter, gives corals their colour and provides nutrients to both partners. It may also be a <a href="https://link.springer.com/chapter/10.1007/978-3-319-75393-5_6">main factor</a> in coral resistance to warmer temperatures.</p>
<p>So far, we have found more diversity than initially expected. This is exciting because it may signal an increased capacity to resist different types of stress. But the work to fully map Ningaloo’s coral diversity has only just begun.</p>
<p>We hope our findings, once finalised, can inform local community management actions such as:</p>
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<li>public education campaigns and signs</li>
<li>managing visitor numbers to reefs</li>
<li>installing public moorings to reduce harm from boat anchoring, especially during coral spawning.</li>
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<p>The information can also be used in broader management actions such as:</p>
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<li>establishing “baseline” conditions from which to measure change</li>
<li>zoning decisions, including the establishment or ramping up of of marine park protections, especially for resilient coral species and individuals</li>
<li>impact assessments following events such as heatwaves</li>
<li>direct conservation actions for iconic, at-risk bommies, such as providing shade to diminish stress from heat</li>
<li>the development of national reef management plans.</li>
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Read more:
<a href="https://theconversation.com/photos-from-the-field-why-losing-these-tiny-loyal-fish-to-climate-change-spells-disaster-for-coral-167119">Photos from the field: why losing these tiny, loyal fish to climate change spells disaster for coral</a>
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<h2>Something worth fighting for</h2>
<p>The stress to coral wrought by recent marine heatwaves compounds damage incurred over decades. The Great Barrier Reef, for example, has <a href="https://theconversation.com/5-major-heatwaves-in-30-years-have-turned-the-great-barrier-reef-into-a-bleached-checkerboard-170719">experienced five</a> major heatwaves in 30 years. </p>
<p>Broadly, making reefs more resilient to these pressures involves:</p>
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<li>resisting, recovering, managing and adapting to shocks across ecosystems</li>
<li>improving governance structures</li>
<li>preparing human communities for change. </li>
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<p>Awareness of the need to increase reef resilience is growing. For example, it formed the basis of a 2017 <a href="https://elibrary.gbrmpa.gov.au/jspui/bitstream/11017/3287/1/GBRMPA%20Blueprint%20for%20Resilience%20-%20Low%20Res.pdf">blueprint</a> for the Great Barrier Reef and a <a href="https://www.barrierreef.org/uploads/Ningaloo-Strategy-v230216.pdf">strategy</a> for the Ningaloo Coast released last year.
But more work is required. </p>
<p>There’s also a need for coordination across Australia’s reef areas. This might include the exchange of knowledge and data between researchers and combined lobbying efforts to better protect reef ecosystems.</p>
<p>What’s more, Traditional Owners must be offered the opportunity to be consulted about, and meaningfully engaged in, protection of reef areas, including <a href="https://theconversation.com/climate-change-will-strike-australias-precious-world-heritage-sites-and-indigenous-knowledge-is-a-key-defence-222393?utm_medium=Social&utm_source=Twitter#Echobox=1707258796-1">co-management of Sea Country</a>.</p>
<p>The <a href="https://australiancoralreefsociety.org">Australian Coral Reef Society</a>, of which I am a councillor, last week released <a href="https://australiancoralreefsociety.org/acrs-letter-calling-parliament-reduce-atmospheric-carbon/">an open letter</a> to the federal government, calling for action on climate change to protect reefs. The task has never been more urgent. </p>
<p>There is still a lot of reef worth fighting for – but only if we act now.</p>
<p><em>The author would like to acknowledge the contribution of Ningaloo marine park managers – in particular, Dr Peter Barnes – to the research she and her colleagues are undertaking.</em></p><img src="https://counter.theconversation.com/content/223207/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Quigley receives funding from the Australian Research Council in the form of the Discovery Early Career Researcher Award (DECRA) and holds a joint position as Principal Research Scientist at Minderoo Foundation, a philanthropic organisation.</span></em></p>The best strategy to protecting Earth’s coral reefs is to dramatically cut greenhouse gas emissions. But in the meantime, we must urgently make corals more resilient.Kate Marie Quigley, DECRA Research Fellow (James Cook University), Principal Research Scientist (Minderoo Foundation), James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2143082023-10-16T19:07:21Z2023-10-16T19:07:21ZCould ‘marine cloud brightening’ reduce coral bleaching on the Great Barrier Reef?<figure><img src="https://images.theconversation.com/files/553900/original/file-20231016-21-cc921e.jpg?ixlib=rb-1.1.0&rect=15%2C10%2C3079%2C1444&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Southern Cross University</span></span></figcaption></figure><p>It might sound like science fiction, but “marine cloud brightening” is being seriously considered as a way to shield parts of the ocean from extreme heat. </p>
<p>We’re using water cannons to spray seawater into the sky. This causes brighter, whiter clouds to form. These low marine clouds reflect sunlight away from the ocean’s surface, protecting the marine life below from the worst of climate change.</p>
<p>Australia’s <a href="https://gbrrestoration.org">Reef Restoration and Adaptation Program</a> – a collaboration between several universities, CSIRO and the Australian Institute of Marine Science – is exploring whether cloud brightening could <a href="https://meetingorganizer.copernicus.org/EGU23/EGU23-17057.html">reduce coral bleaching</a>. As an oceanographer and engineer I lead the program’s research into <a href="https://gbrrestoration.org/program/cooling-and-shading/">cooling and shading</a> techniques. </p>
<p>We started exploring cloud brightening after the mass bleaching event in 2016. First, we needed to develop and test the underlying technologies in the lab. Then we began pilot testing in the central Great Barrier Reef near Townsville during January 2020. After several iterations we have now moved beyond “proof of concept” to investigating the response of the clouds themselves.</p>
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<figcaption><span class="caption">The Cloud Brightening Field Trip of 2021 (Southern Cross University)</span></figcaption>
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Read more:
<a href="https://theconversation.com/new-australian-laws-for-engineering-the-ocean-must-balance-environment-protection-and-responsible-research-209036">New Australian laws for ‘engineering’ the ocean must balance environment protection and responsible research</a>
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<h2>A bright idea</h2>
<p>British cloud physicist John Latham originally proposed cloud brightening in 1990 as a way to <a href="https://www.nature.com/articles/347339b0">control global warming</a> by altering Earth’s energy balance. He calculated that brightening clouds across the most susceptible regions of the world’s oceans could counteract the global warming caused by a doubling of preindustrial atmospheric carbon dioxide. That’s a level likely to be reached by the year 2060.</p>
<p>Recently, scientists have begun to consider regional rather than global application of cloud brightening. Could brightening clouds directly over the Great Barrier Reef for a few months <a href="https://agu.confex.com/agu/os18/meetingapp.cgi/Paper/314949">reduce coral bleaching</a> during a marine heat wave? </p>
<p>Modelling studies are encouraging and suggest it could <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.201296">delay the expected decline in coral cover</a>. This could buy valuable time for the reef while the world transitions away from fossil fuels. </p>
<p>Lowering the heat stress on the ecosystem would produce <a href="https://gbrrestoration.org/wp-content/uploads/2020/09/T6-Modelling-Methods-and-Findings_26April_FINAL3.pdf">other benefits</a> when combined with other reef interventions – such as improved control of invasive crown of thorns starfish and planting of corals with increased heat tolerance. </p>
<p>But these studies also show there’s a limit to what can be achieved. Long-term benefits are only possible if the cloud brightening activity occurs alongside aggressive emissions reductions. </p>
<p>Cloud brightening does have <a href="https://www.youtube.com/watch?v=lylzQsZUZnk">risks as well as benefits</a>, but the prospect of intermittent regional use is very different to large-scale “solar geo-engineering” proposals for shading and cooling the whole planet.</p>
<p>We expect the regional effect will be short-lived and reversible, which is reassuring. The technology must be operated continuously to modify clouds and could be stopped at any time. The sea salt particles sprayed in the process typically only persist in the atmosphere for <a href="https://www.nature.com/articles/s41467-021-25579-3">one to several days</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo from the university's aircraft looking down at the Great Barrier Reef" src="https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553933/original/file-20231016-29-22ul5k.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">Southern Cross University’s aerosol and cloud microphysics aircraft operating over the Southern Great Barrier Reef.</span>
<span class="attribution"><span class="source">Southern Cross University</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-are-poised-to-pass-1-5-of-global-warming-world-leaders-offer-4-ways-to-manage-this-dangerous-time-213649">We are poised to pass 1.5℃ of global warming – world leaders offer 4 ways to manage this dangerous time</a>
</strong>
</em>
</p>
<hr>
<h2>How do you brighten a cloud?</h2>
<p>A warm cloud (as opposed to an ice cloud) is a collection of small water droplets floating in the air. </p>
<p>A cloud of many small droplets is brighter than one with fewer large droplets – even if both clouds contain the same amount of water overall. </p>
<p>Every droplet begins with the condensation of water vapour around a nucleus, which can be almost any kind of tiny particle suspended in air. </p>
<p>Typically, in the lower atmosphere over land there are thousands to tens of thousands of these tiny particles suspended in every cubic centimetre of air. We call these airborne particles “aerosols”.</p>
<p><a href="https://earth.gsfc.nasa.gov/climate/data/deep-blue/aerosols">Aerosols may be natural</a> such as dust, sea salt, pollen, ash and sulphates. Or they may come from human activity such as burning fossil fuels or vegetation, manufacturing, vehicle exhaust and aerosol spray cans. </p>
<p>In very clean maritime air, the aerosols available to form clouds are mainly <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2007.2043">sulphates and sea salt crystals</a>. And they are few and far between, only a <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2006GB002787">few hundred per cubic centimetre</a>.</p>
<p>When a cloud forms under these conditions, water vapour is forced to condense around fewer nuclei, creating <a href="https://www.sciencedirect.com/science/article/pii/0004698174900043">larger droplets and fewer of them</a>. Large droplets reflect less light for the same volume of cloud water. </p>
<p>To brighten such clouds, we can spray large quantities of microscopic seawater droplets into the air. This process of atomising seawater mimics the generation of sea salt aerosols by wind and waves in the ocean. If these are incorporated into a cloud and create extra droplets, the cloud will be brightened. </p>
<p>Sea salt also provides additional shade by <a href="https://acp.copernicus.org/articles/17/13071/2017/">direct scattering of light</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo of the latest cloud brightening generator (V model) in action, on board a vessel, with a person standing alongside it. The cannon is about as tall as the person." src="https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553894/original/file-20231016-23-h8j16h.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">The latest cloud brightening generator (V model) in action.</span>
<span class="attribution"><span class="source">Southern Cross University</span></span>
</figcaption>
</figure>
<h2>Testing the theory</h2>
<p>Although scientists have researched cloud brightening for more than 30 years, no one had ever directly tested the theory. In Australia, we have now developed technology to a point where we are starting to measure the response of the clouds. </p>
<p>We are beginning such tests with the support and permission of Traditional Owners, who have sustainably managed their Sea Country for tens of thousands of years. </p>
<p>Our research program involves more than 15 research institutions and has multiple levels of <a href="https://gbrrestoration.org/our-team/governance/">governance</a> and oversight. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/out-of-danger-because-the-un-said-so-hardly-the-barrier-reef-is-still-in-hot-water-210787">Out of danger because the UN said so? Hardly – the Barrier Reef is still in hot water</a>
</strong>
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<hr>
<h2>Not so far-fetched</h2>
<p>Most people probably don’t realise we are already inadvertently brightening the clouds. The Intergovernmental Panel on Climate Change estimates humanity’s unintentional release of aerosols <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter08_FINAL.pdf">offsets around 30%</a> of the warming effect due to greenhouse gases. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1577608215059120129"}"></div></p>
<p>Sulphates in ship exhaust are such a potent source of aerosols for droplet formation, the passage of ships leaves cloud trails called <a href="https://climate.nasa.gov/climate_resources/54/ship-tracks/">ship tracks</a>. </p>
<p>When the International Maritime Organisation introduced new rules limiting the sulphur content of marine fuels, the number and extent of ship tracks <a href="https://www.nasa.gov/missions/aqua/nasa-study-finds-evidence-that-fuel-regulation-reduced-air-pollution-from-shipping/">drastically reduced</a>, especially in the Northern Hemisphere. A <a href="https://www.science.org/content/article/changing-clouds-unforeseen-test-geoengineering-fueling-record-ocean-warmth">recent study</a> even suggests the devastating heat wave that swept the Northern Hemisphere earlier this year was worsened by the absence of ship tracks. </p>
<p>The world-first research we are conducting in Australia aims to determine if we could harness the clouds in an effective, environmentally responsible and socially acceptable manner for the future conservation of one of our most precious ecosystems.</p><img src="https://counter.theconversation.com/content/214308/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Patrick Harrison receives funding from the The Reef Restoration and Adaptation Program which is funded by the partnership between the Australian Governments Reef Trust and the Great Barrier Reef Foundation.
He would like to acknowledge the many indigenous traditional owners of the Great Barrier Reef whom have supported this work and thank them for their valuable insights and contribution to the design and conduct of the research. </span></em></p>Australian is experimenting with marine cloud brightening to cool and shade the Great Barrier Reef. Here’s how it works.Daniel Patrick Harrison, Senior Lecturer, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2110882023-10-12T21:13:09Z2023-10-12T21:13:09ZHow clouds protect coral reefs, but will not be enough to save them from us<iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/how-clouds-protect-coral-reefs-but-will-not-be-enough-to-save-them-from-us" width="100%" height="400"></iframe>
<p>Coral reefs are vital <a href="https://www.noaa.gov/education/resource-collections/marine-life/coral-reef-ecosystems">ecosystems</a> for people and coastal communities. They provide <a href="https://www.coast.noaa.gov/states/fast-facts/coral-reefs.html">food and livelihoods</a> and protect coastlines from storms, contribute to local economies and preserve cultural heritage.</p>
<p>However, warming ocean temperatures as a result of human-made climate change present considerable risks to the reefs. The recent rise in <a href="https://doi.org/10.1038/nature21707">coral bleaching</a> all over the world is the most visible impact.</p>
<p>But what is <a href="https://oceanservice.noaa.gov/facts/coral_bleach.html">coral bleaching</a>? Coral bleaching is a phenomenon that occurs when the white skeleton of the corals becomes visible after the microalgae that live inside their translucent tissues are expelled. </p>
<p>Even though coral reefs can <a href="https://reefresilience.org/stressors/bleaching/bleaching-biology/">recover</a> from bleaching events, the process, much like the regrowth of a forest following a windstorm or wildfire, requires a considerable amount of time. And, as our research has shown, an appreciation of the role of cloud cover.</p>
<h2>Relief in the clouds</h2>
<p>Although coral bleaching is generally linked only to ocean temperatures, the process itself is a product of the interaction between high <a href="https://reefresilience.org/stressors/bleaching/bleaching-biology/">temperatures and sunlight levels in a given area</a>. </p>
<p>If the temperatures are high enough, the coral and microalgae become more light-sensitive. When combined with <a href="https://doi.org/10.3389/fmicb.2014.00422">excessive sunlight</a>, this sensitivity harms the microalgae which, in turn, results in the production of chemical compounds called <a href="https://doi.org/10.1242/jeb.009597">reactive oxygen species</a>. These compounds are harmful to many species and in the case of reefs cause the coral to expel its microalgae.</p>
<p>In the same way that clouds protect us from harmful exposure to UV rays, clouds also provide a protective barrier for the world’s coral reefs. Field studies of coral bleaching events in <a href="https://www.int-res.com/abstracts/meps/v222/p209-216/">French Polynesia</a> and in the <a href="https://doi.org/10.1038/s41598-019-40150-3">Republic of Kiribati</a> found that periods of cloudiness may have reduced the bleaching severity and extent. </p>
<p>Climate change is projected to kill off most of the world’s coral reefs, even in scenarios with only <a href="http://dx.doi.org/10.1038/nclimate1674">1.5 C</a> of global warming. Yet, to date, most analysis has only considered the effect of temperature. Could incorporating clouds change the forecast?</p>
<h2>Considering cloudiness</h2>
<p>In order to understand how cloudiness might influence the response of coral reefs to climate change, <a href="https://doi.org/10.1371/journal.pclm.0000090">our recent study</a> used a <a href="https://doi.org/10.1371/journal.pone.0281719">global historical database</a> containing almost 38,000 coral bleaching reports to train an algorithm that estimates bleaching severity based on incoming light and temperature stress. </p>
<p>Our algorithm was then <a href="https://www.climateneutralgroup.com/en/news/five-future-scenarios-ar6-ipcc/">applied to four different future climate scenarios</a> on the world’s coral reefs to assess if and when bleaching conditions would become too frequent for reefs to recover. The results indicate that under a low emissions scenario, increased cloudiness would indeed have an effect on the coral bleaching conditions. This means that corals would have more time to recover from the impacts of rising temperatures and improve their resilience. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coral-reefs-how-climate-change-threatens-the-hidden-diversity-of-marine-ecosystems-211007">Coral reefs: How climate change threatens the hidden diversity of marine ecosystems</a>
</strong>
</em>
</p>
<hr>
<p>However, even under a low carbon emission scenario, this extra time will not be enough to prevent more than 70 per cent of global reefs experiencing frequent bleaching conditions with not enough time in between to fully recover.</p>
<p>This highlights the severity of the coral bleaching crisis caused by thermal stress and the limitations of relying solely on cloudiness as a protective mechanism. Simply put, while clouds can offer some relief to corals, they cannot mitigate the long-term consequences of climate change when the sea surface temperature becomes too high.</p>
<h2>Clear implications</h2>
<p>Cloud cover may offer temporary relief to coral reefs by delaying the adverse environmental conditions responsible for coral bleaching. However, that seems to be partially true only in the lowest emission scenario which would be possible only if we dramatically cut greenhouse gas emissions.</p>
<p>Without doing that, dangerously frequent bleaching conditions are unavoidable and reefs will continue to be threatened even if we cut down emissions now. Moreover, we also need to get serious about habitat and biodiversity protection <a href="https://www.epa.gov/coral-reefs/threats-coral-reefs">to increase resilience</a>. </p>
<p>Only by doing this could coral reefs stand a chance at surviving the increasing pressures of climate change. Any other approach has its head in the clouds.</p><img src="https://counter.theconversation.com/content/211088/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Pedro C. González Espinosa receives funding from the Nippon Foundation Ocean Nexus, School of Resource and Environmental Management (REM), Simon Fraser University (SFU). </span></em></p><p class="fine-print"><em><span>Simon Donner receives funding from Natural Sciences and Engineering Research Council and the Social Sciences and Humanities Research Council.</span></em></p>Understanding how both cloud cover and temperature work to promote coral bleaching provides valuable insight into how reefs will change over various climate scenarios.Pedro C. González Espinosa, Postdoctoral Reserach Fellow, The School of Resource and Environmental Management, Simon Fraser UniversitySimon Donner, Professor, Department of Geography, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2113992023-09-05T12:29:58Z2023-09-05T12:29:58ZClimate change is destroying reefs, but the effects are more than ecological – coral’s been woven into culture and spirituality for centuries<p>Hurricane Idalia made landfall on Florida’s Gulf Coast on Aug. 30, 2023, bringing <a href="https://theconversation.com/what-is-hurricane-storm-surge-and-why-can-it-be-so-catastrophic-145369">surging seas</a> and <a href="https://apnews.com/article/florida-hurricane-idalia-2136985ceea53f5deb600c43aeea1138">winds over 100 mph</a>. Meanwhile, another climate emergency has been unfolding along Florida’s coast this summer: a <a href="https://doi.org/10.1126/science.adk0565">marine heat wave</a> bleaching corals throughout the world’s <a href="https://www.floridamuseum.ufl.edu/southflorida/habitats/corals/geographical-distribution/">third-largest barrier reef</a>.</p>
<p>Similarly, ocean temperatures in many parts of the Atlantic and Pacific are at <a href="https://www.climatecentral.org/climate-matters/record-ocean-heat-impacts-from-hurricanes-to-corals">record highs</a>, with reefs <a href="https://www.theguardian.com/environment/2023/aug/11/coral-bleaching-central-america">from Colombia</a> <a href="https://www.sbs.com.au/news/podcast-episode/concern-grows-over-unexpected-coral-bleaching-on-the-great-barrier-reef/pbi69ju9t">to Australia</a> showing signs of stress in recent years. Scientists warn that the world may be witnessing the start of a <a href="https://earth.google.com/web/@24.4430141,123.8161774,1.99338294a,0d,60y,358.27417338h,113t,0r/data=CkoSSBIgY2EwYzk0ZGNhN2I4MTFlN2I1ZDBiNzRhMWFlNGU2MDMiJGVmZWVkX29jZWFuX2FnZW5jeV9jb3JhbF9ibGVhY2hpbmdfMSIwCixBRjFRaXBPQXhSWk82WHppY1Z0QkJWOVlPOThCMmt2NkRZNTViR2p5azNFcBAF">global coral-bleaching event</a>, which would be <a href="https://www.cnbc.com/2023/08/18/noaa-florida-coral-bleaching-event-could-go-global.html">the fourth on record</a> – and while corals <a href="https://oceanservice.noaa.gov/facts/coral_bleach.html">can survive bleaching</a>, they won’t if the waters stay warm for too long.</p>
<p>Large-scale reef destruction tends to be measured in <a href="https://coast.noaa.gov/states/fast-facts/coral-reefs.html">biological and economic terms</a>. Reefs support about 25% <a href="https://doi.org/10.1371/journal.pone.0025026">of all marine species</a>, protect human lives and property by buffering shorelines and bolster the worldwide economy through fishing and tourism. </p>
<p>But coral’s loss also takes an enormous spiritual, psychological and cultural toll – one of the main topics of <a href="https://miamioh.edu/profiles/cas/michele-navakas.html">my research</a> and recent book, “<a href="https://press.princeton.edu/books/paperback/9780691240091/coral-lives">Coral Lives</a>.” Centuries of writing, painting, storytelling and rituals show that coral has given meaning to human lives for nearly as long as we’ve been around to marvel at it.</p>
<h2>Protective powers</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A Renaissance painting of a woman in a white cap holding a baby who is draped in white fabric and wearing a red necklace." src="https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=756&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=756&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545609/original/file-20230830-19-ug6tbg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=756&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 detail from the 15th-century painting ‘The Senigallia Madonna,’ by Piero della Francesca, depicts Jesus with coral.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/italy-marche-pesaro-urbino-urbino-marche-national-gallery-news-photo/132702015?adppopup=true">Mondadori Portfolio/Hulton Fine Art Collection via Getty Images</a></span>
</figcaption>
</figure>
<p>From the Middle Ages until the 19th century, anxious new parents across Europe and North America clasped red coral necklaces and bracelets to their children’s bodies and gave them red coral to hold – and even teethe on – because coral symbolized physical and spiritual protection. Early Christian art from the medieval and Renaissance periods often features the infant Jesus in red coral, which scholars suggest may also be because its color <a href="https://surface.syr.edu/beads/vol16/iss1/4/">symbolized the blood of Christ</a>.</p>
<p>Coral encircles the necks and wrists of babies and children in more secular portraits, too, particularly during the 18th and 19th centuries. Often a child holds the “coral and bells,” a combination toy and teething aid: Children would alternately shake it as a rattle and chew on the red coral shaft to soothe sore gums. <a href="https://press.princeton.edu/books/paperback/9780691240091/coral-lives">The item was cherished</a> by the families of presidents and poets alike, from George Washington to Henry Wadsworth Longfellow, <a href="https://www.nps.gov/long/blogs/coral-and-silver-baby-rattle.htm">who even wrote about it</a>. “Coral and bells” were such a popular christening present that shops could barely keep it in stock.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up photo of a tiny red dagger-shaped item with an ornate silver handle." src="https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545614/original/file-20230830-25-feg4b1.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">A ‘coral and bells’ toy made in New York in the 18th century.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/rattle-whistle-and-bells-1735-45-made-in-new-york-new-york-news-photo/1216161314?adppopup=true">Sepia Times/Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<p>For these families and countless others across centuries, coral was far more than ornamental. By giving a child coral, parents were protecting what was most precious to them: their child’s life. </p>
<h2>The birth of coral</h2>
<p>Belief in the protective powers of coral dates to at least the classical period. According to <a href="https://www.bl.uk/collection-items/ovids-metamorphoses">the first-century Roman poet Ovid</a>, coral carried petrifying powers because it <a href="https://www.jstor.org/stable/3050690">originally emerged from the touch of Medusa</a>, the snake-haired Gorgon whose stare could turn others to stone. In <a href="https://ovid.lib.virginia.edu/trans/Metamorph4.htm">his epic poem “Metamorphoses</a>,” Ovid describes the hero Perseus severing Medusa’s head and laying it on a bed of seaweed that then hardened into coral. By the medieval period, this story gave rise to popular beliefs that wearing coral could ward off the “evil eye.” </p>
<p>Coral was also believed to have curative properties. In the “<a href="https://dpul.princeton.edu/gutenberg/catalog/q237hx283">Historia naturalis</a>,” an encyclopedia of the natural world, Roman author Pliny the Elder wrote of the <a href="https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D32%3Achapter%3D11">sacred and medicinal qualities of coral</a>. The material could remedy a variety of ailments when ingested, he claimed – which also explains why people once thought it was healthy for children to chew on coral.</p>
<p>Modern medicine, of course, argues against these ideas. But during historical periods when <a href="https://ourworldindata.org/child-mortality-in-the-past">child mortality rates may have been almost 50%</a>, coral calmed anxious parents’ fears.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A formal portrait of three young girls in brightly colored dresses." src="https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545640/original/file-20230830-16-camv9y.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">The child at left wears a coral necklace in William Matthew Prior’s portrait of three daughters of African American real estate investor Samuel Copeland.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/William_Matthew_Prior_-_Three_Sisters_of_the_Copeland_Family_-_48.467_-_Museum_of_Fine_Arts.jpg/512px-William_Matthew_Prior_-_Three_Sisters_of_the_Copeland_Family_-_48.467_-_Museum_of_Fine_Arts.jpg">BotMultichillT/Wikimedia Commons/Museum of Fine Arts Boston</a></span>
</figcaption>
</figure>
<p>To this day, in some parts of the world, coral continues to provide a sense of control over situations that are largely out of our hands. In southern Italy, people give one another the “cornicello” for good luck: a small, horn-shaped charm frequently made of red coral. Some rosaries, too, are still <a href="https://americanhistory.si.edu/collections/search/object/nmah_1143060">made of red coral beads</a>, just as they were in the Middle Ages.</p>
<h2>Community bonds</h2>
<p>Beyond protection, coral can also symbolize belonging. Throughout the African diaspora during the 18th and 19th centuries, free and enslaved women in many communities wore red coral jewelry, particularly on special occasions, to commemorate a shared past and create new bonds.</p>
<p>Groups of women in Jamaica and other parts of the Caribbean, for example, <a href="https://press.princeton.edu/books/paperback/9780691240091/coral-lives">wore coral necklaces, earrings and bracelets during Jonkonnu</a>, a Christmas holiday masquerade of West African origins that incorporates traditional music and dance. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A colored drawing of women in elaborate costumes with white and red skirts." src="https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=504&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=504&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=504&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=633&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=633&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545140/original/file-20230828-17-la7rj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=633&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 sketch of Jonkonnu celebrations by 19th century Jamaican artist Isaac Mendes Belisario.</span>
<span class="attribution"><a class="source" href="http://www.slaveryimages.org/s/slaveryimages/item/2308">Slavery Images: A Visual Record of the African Slave Trade and Slave Life in the Early African Diaspora</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>As historian <a href="https://www.gvsu.edu/history/steeve-buckridge-62.htm">Steeve O. Buckridge</a> explains, these women <a href="https://www.uwipress.com/9789766401436/the-language-of-dress/">used clothing and jewelry</a> to communicate their identities nonverbally. Wearing coral was a way to preserve links to the African cultures from which slavery had severed these women. In many cultures, red coral beads were – and in some cases still are – objects of spiritual, economic and cultural significance. </p>
<p>In fact, coral was so valuable that it came to play a violent role in history. In coastal areas of Western Africa, coral became <a href="https://hal.science/hal-01991948/">currency in the transatlantic slave trade</a>: Slave traders exchanged coral for people.</p>
<p>But when diasporic women wore coral, it became part of their choice to create a different present and future. As scholar <a href="https://cssh.northeastern.edu/faculty/elizabeth-dillon/">Elizabeth Maddock Dillon</a> has also observed, each piece of their elaborate Jonkonnu costumes announced “not only splendor and beauty but <a href="https://www.dukeupress.edu/new-world-drama">a form of social belonging</a>” within different “kinship groups” of their own devising. Coral simultaneously signified slavery and hope for new possibilities.</p>
<h2>Forging the future</h2>
<p>After the Civil War, Black communities in the United States embraced coral for another reason. During Reconstruction, as these communities struggled to create a more just country, writers, religious leaders and activists <a href="https://press.princeton.edu/books/paperback/9780691240091/coral-lives">turned to reefs as an inspiring model</a>.</p>
<p>Even massive coral reefs are made up of millions of microscopic animals called polyps, which many people in the 19th century understood as “laborers” working together to build the reef. According to African American poet and civil rights advocate <a href="https://www.womenshistory.org/education-resources/biographies/frances-ellen-watkins-harper">Frances Ellen Watkins Harper</a>, reefs expand by sustaining others, rather than devaluing or displacing them. In her 1871 poem “<a href="https://catalog.hathitrust.org/Record/009567459">The Little Builders</a>,” Harper chose reefs as an analogy for how listeners and readers, Black and white, should work to build the social and financial bonds equality would depend on.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white photograph of a woman in dark clothing standing formally while holding on to a chair." src="https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=769&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=769&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=769&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=967&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=967&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545641/original/file-20230830-27-x1m060.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=967&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Frances Ellen Watkins Harper, pictured in the 19th century book ‘Women of distinction: remarkable in works and invincible in character.’</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/internetarchivebookimages/14598047448/">Internet Archive Book Images/Flickr</a></span>
</figcaption>
</figure>
<p>But Harper knew that outcome was by no means certain. That’s why the coral analogy worked so well. As Charles Darwin explained in 1842 in a famous <a href="http://darwin-online.org.uk/content/frameset?pageseq=1&itemID=F271&viewtype=text">treatise on coral</a>, reefs are formed by so many relationships among different individual organisms across vast periods of time that their future form and shape can only be unpredictable.</p>
<p>As <a href="https://press.princeton.edu/books/paperback/9780691240091/coral-lives">my book</a> shows, in that unpredictability Black writers like Harper found hope. To them it meant that the actions of one single and seemingly insignificant individual might help transform an entire system.</p>
<h2>Grief and preservation</h2>
<p>Coral’s biological uniqueness and central role in sustaining other forms of life, including humans, are reasons enough to preserve it. And scientists <a href="https://theconversation.com/the-heroic-effort-to-save-floridas-coral-reef-from-extreme-ocean-heat-as-corals-bleach-across-the-caribbean-210974">are making extraordinary efforts</a>, such as <a href="https://www.nytimes.com/2023/07/31/climate/coral-reefs-heat-florida-ocean-temperatures.html">relocating threatened species</a> to dry tanks on land and developing <a href="https://doi.org/10.1126/science.adk4685">tools to predict marine heat waves</a> months in advance. </p>
<p>But for centuries, coral has also shaped thoughts about difficult human problems, from love and loss to social injustice. Reefs have provided knowledge, stories, hopes and histories in many cultures, far beyond the handful mentioned here. As we lose coral, then, we are also losing a material that has given us vital ways to understand and act within an increasingly chaotic world.</p><img src="https://counter.theconversation.com/content/211399/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michele Navakas has received funding from the National Endowment for the Humanities for research on which this article is based.</span></em></p>Coral has been incorporated into traditions, art and even religion in communities around the world.Michele Currie Navakas, Professor of English, Miami UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2118522023-08-22T14:24:09Z2023-08-22T14:24:09ZRemote Pacific coral reef shows at least some ability to cope with ocean warming – new study<figure><img src="https://images.theconversation.com/files/543575/original/file-20230820-225972-21eyt4.jpeg?ixlib=rb-1.1.0&rect=0%2C13%2C1736%2C1101&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A healthy coral reef in Palau in the western Pacific Ocean.</span> <span class="attribution"><span class="source">Liam Lachs</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Unprecedented ocean temperatures are triggering mass coral bleaching events across the <a href="https://coralreefwatch.noaa.gov/satellite/bleachingoutlook_cfs/weekly_90.php">world</a>. This year, the world’s third largest barrier reef, in Florida, is already being <a href="https://twitter.com/AFP/status/1685299136764280833">hit hard</a>.</p>
<p>New research by my colleagues and I offers a glimmer of hope: coral reefs we studied in the Pacific appear to have increased their resistance to high ocean temperatures. But this can only improve their long-term futures if there is strong global action on reducing carbon emissions.</p>
<p>We know that corals will need to withstand rising ocean temperatures to survive under climate change. And we know reef-building corals are acutely sensitive to even small increases in temperature. What we don’t yet know is whether their “thermal tolerance” – essentially their ability to handle high temperatures – can keep pace with ocean warming.</p>
<p>In normal conditions, corals live in symbiosis with microscopic algae housed within their tissue. These algae give corals their <a href="https://theconversation.com/revealed-why-some-corals-are-more-colourful-than-others-36866">beautiful colours</a>, and provide them with food through photosynthesis, just like plants (corals are animals, don’t forget). </p>
<p>However, this relationship <a href="https://www.cell.com/current-biology/pdf/S0960-9822(20)31591-8.pdf">breaks down when it’s too hot</a>: the microalgae are expelled, leaving the corals stark white, or bleached, which usually leads to death. Extreme temperatures can even kill corals outright, bypassing the gradual bleaching process.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bleached coral" src="https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543509/original/file-20230818-15-ee0qxl.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mass bleaching in the Maldives in 2016 which led to many corals dying.</span>
<span class="attribution"><a class="source" href="https://link.springer.com/chapter/10.1007/978-3-030-20389-4_13">Stephen Bergacker</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In our new study published in <a href="https://doi.org/10.1038/s41467-023-40601-6">Nature Communications</a> on the coral reefs of Palau, a nation of more than 300 small islands in the western Pacific Ocean, we found that the tolerance of corals to warm conditions has likely increased over the past three decades.</p>
<h2>Testing thermal tolerance</h2>
<p>Palau experienced intense marine heatwaves in 1998, 2010 and 2017, but interestingly, each successive event led to less coral bleaching. Such a phenomenon has also been recorded in <a href="https://www.sciencedirect.com/science/article/pii/S0960982221014901">Australia’s Great Barrier Reef</a>, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0033353">south-east Asia</a>, and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070443">French Polynesia</a>. </p>
<p>Is this evidence that coral communities are adapting to hotter temperatures? We set out to test whether thermal tolerance has likely increased for at least those reefs in Palau, and if so, how quickly. </p>
<p>Our international team of researchers designed a simulation study, drawing on 35 years of sea surface temperature data and historic observations of bleaching. We found that the thermal tolerance of the coral communities in Palau has likely increased at 0.1°C/decade. That’s slightly less than the increase in global temperatures (about <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature">0.18°C/decade</a>) but does suggest these coral reefs have an innate capacity for climate resilience.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="scuba diver above coral reef" src="https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543578/original/file-20230820-153592-nwaj3l.jpeg?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">Researcher conducting a 3D mapping survey of a coral reef in Palau.</span>
<span class="attribution"><span class="source">Eveline van der Steeg</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>How coral reefs are adapting to warmer oceans</h2>
<p>More work is needed to pin down exactly what has happened, but there are various mechanisms that could explain this. </p>
<p>One involves the turnover of species. There are hundreds of different coral species, each with a <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1461-0248.2012.01861.x?casa_token=8vXhQAvJA0cAAAAA:6E3XAgHUbuzWIXTrFc3Cq6mCXOI1w7cG8RrgsUb0tLnrOfYZK2aMenY5wMlsBb7Cg_EbafteVgUyVn0">unique evolutionary history and life strategy</a>. Some, like branching <em>Acropora</em>, are fast-growing yet sensitive to temperature, while others, like massive <em>Porites</em>, are slow-growing but more stress tolerant. </p>
<p>Severe heatwaves can weed out the sensitive species, leaving the coral reef dominated by the tougher ones, which can compromise important ecological functions like reef growth and habitat provision for seafood species.</p>
<p>The second mechanism is genetic adaptation. Thermal tolerance is a complex trait that is likely <a href="https://www.frontiersin.org/articles/10.3389/fmars.2017.00434/full">influenced by thousands of genes</a>, but most corals only have some of these. Following Darwin’s theory of survival of the fittest, natural selection can choose the winners under climate change. Over multiple generations and many rounds of selection, thermal tolerance genes can become more prevalent, and thus increase the thermal tolerance of species populations.</p>
<p>The final explanation involves individual acclimatisation. Even within the lifetime of a single coral, its ability to survive thermal stress events can change. As the saying goes, “<a href="https://www.the-scientist.com/features/environmental-memory-how-corals-are-adjusting-to-warmer-waters-69640">what doesn’t kill you makes you stronger</a>”, and so, being exposed to low-level thermal stress can later improve chances of survival under high-level thermal stress.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three photos of corals" src="https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543589/original/file-20230821-229778-hhvlx0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">a) Community of corals with high species diversity; b) two corals of the same species with contrasting bleaching susceptibility; c) the symbiotic microalgal community housed within coral tissues.</span>
<span class="attribution"><a class="source" href="https://www.oist.jp/image/coral-polyps-and-their-symbionts">Liam Lachs; Laurie Raymundo; OIST</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>To make things more complicated, all of these processes – species-turnover, genetic adaptation and acclimatisation – can also occur in the microalgae communities living within each coral. Scientists like me will need to disentangle the mechanisms that have driven potential shifts in thermal tolerance in Palau and elsewhere.</p>
<h2>What does the future hold?</h2>
<p>Can coral thermal tolerance continue increasing into the future? If so, then will it be fast enough to keep pace with ocean warming? Our study tackles these questions using high-resolution future temperature projections from 17 <a href="https://www.carbonbrief.org/qa-how-do-climate-models-work/">global climate models</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="three graphs" src="https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=942&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=942&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543593/original/file-20230821-25-dna4wg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=942&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Projections of coral bleaching in Palau: if the Paris Agreement is achieved, in a middle-of-the-road scenario, and a worst-case scenario. An increase in thermal tolerance (blue line) buys some time, but coral reefs will still struggle unless climate change is halted.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41467-023-40601-6">Lachs et al</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our analysis reaffirms the scientific consensus, that ultimately the future of coral reefs depends on rapidly reducing carbon emissions. However, if coral thermal tolerance can continue rising, then bleaching could be avoided on some reefs, or at least delayed. </p>
<p><a href="https://doi.org/10.1038/s41467-023-40601-6">Our study</a> and <a href="https://doi.org/10.1029/2021GL094128">others</a> have identified reefs with some level of innate climate resilience. This might buy us some time, but securing a future for coral reefs still hinges on rapid climate action. As our oceans get hotter, fewer reefs will escape bleaching conditions. </p>
<p>There are promising conservation measures, restoration efforts and more experimental interventions such as <a href="https://theconversation.com/coral-meet-coral-how-selective-breeding-may-help-the-worlds-reefs-survive-ocean-heating-166412">selective breeding</a> to increase thermal tolerance. All of these might <a href="https://www.sciencedirect.com/science/article/pii/S0006320721001592">help corals persist into the future</a>, but reducing carbon emissions is ultimately the only sure bet.</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>
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<p class="fine-print"><em><span>Liam Lachs receives funding from the Natural Environment Research Council's ONE Planet Doctoral Training Programme. </span></em></p>This may buy us time, but many reefs are still doomed without serious action on climate change.Liam Lachs, PhD Candidate in Climate Change Ecology and Evolution, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2093882023-08-10T19:59:25Z2023-08-10T19:59:25ZAccelerated evolution and automated aquaculture could help coral weather the heat<p>Coral on the Great Barrier Reef has regrown strongly after the big losses of 2016 and 2017, when <a href="https://www2.gbrmpa.gov.au/learn/threats/sea-temperature">water temperatures</a> were significantly above the long-term average. While this is good news, it’s largely luck. The reef experienced mass bleaching in 2020 and 2022, but temperatures cooled just in time to prevent extensive coral deaths. </p>
<p>But the reef’s luck may be about to run out. Hotter El Niño conditions are returning to the Pacific, driving <a href="https://coralreefwatch.noaa.gov/data_current/5km/v3.1_op/daily/png/ct5km_baa-max-7d_v3.1_nwcl_current.png">warmer ocean temperatures</a>. The past few months have seen global temperature records smashed. Already, reefs in Florida, the Caribbean and parts of the Pacific are bleaching. The looming southern summer is a significant concern. </p>
<p>Can anything be done? Keeping emissions under control is obviously vital. But we can also support the Great Barrier Reef’s resilience by speeding up natural adaptation processes. </p>
<p>In our paper <a href="https://doi.org/10.1126/science.adi3023">published today</a> in Science, we describe methods of accelerating the natural evolution of heat-tolerant corals, next-generation aquaculture to rear large numbers of baby corals, and collaborative decision-making with First Nations groups to place these corals onto the Great Barrier Reef at meaningful scale.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="national sea simulator corals" src="https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542086/original/file-20230810-23-ax7kkt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A scientist examines baby coral at our National Sea Simulator, where we research heat tolerant corals and large scale coral aquaculture.</span>
<span class="attribution"><span class="source">AIMS</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>How to breed heat-tolerant coral</h2>
<p>Corals are very different in how they tolerate heat. Some can put up with hot water for longer, whereas others bleach at lower temperatures. </p>
<p>Globally, bleaching thresholds have increased by 0.5°C in a decade. That is, reefs are actually becoming more tolerant of heat. This is likely because more sensitive species and colonies have died off or become less abundant. </p>
<p>Within species, we know individual corals in warmer waters are typically more tolerant than those in cooler waters. </p>
<p>Understanding why some corals have better heat tolerance, and how these attributes can be passed on, means we can figure out which corals are best placed to adapt. Then we can start selectively breeding them.</p>
<p>Coral reefs support a huge diversity of lifeforms, from fish to shrimp to rays and sharks. But on a tiny scale, coral polyps have their own microbial ecosystems, ranging from symbiotic algae which give coral its colour – and much of its food, from photosynthesis – through to the rest of the <a href="https://www.barrierreef.org/news/explainers/coral-microbiome">coral microbiome</a>. </p>
<p>To breed coral better able to adapt to the heat, we have to understand how their microbiome works. One group of symbiotic algae (<em>Durusdinium</em>) living inside coral can actually give their host the gift of increased heat tolerance, though often at the cost of reduced growth. </p>
<p>But if we assist the evolution of other coral-associated algae (<em>Cladocopium</em>), we find heat tolerance of both coral and algae improves, usually without compromising other survival traits. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="coral scientist" src="https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542088/original/file-20230810-29-ellk87.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">An AIMS coral scientist examining young coral on a seeding device.</span>
<span class="attribution"><span class="source">T.Whitman/AIMS</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This means we can inoculate the offspring of selectively bred corals with these algae to achieve greater heat tolerance. These methods have now been tested in the laboratory and should scale for mass production.</p>
<p>By interbreeding wild colonies of the same species of coral, we’ve found heat tolerance can be passed to the next generation. </p>
<p>Our researchers are developing tools to pick out these naturally more resilient individuals, during bleaching events or with rapid heat stress experiments. We are also analysing corals’ DNA to identify genetic markers.</p>
<p>Then we measure how heat tolerance and genetic diversity is maintained in the aquaculture facility and back in field conditions. </p>
<p>So while assisted evolution is still very new, our results are encouraging. There is real potential to increase coral heat tolerance to improve survival in hotter seas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="coral spawning" src="https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542077/original/file-20230810-28-7n4kt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coral spawning is an event on the reef. Can selective breeding of coral keep them healthy?</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Accelerate aquaculture to achieve scale</h2>
<p>This year’s marine heatwaves are breaking records. To boost our chances of preserving the Great Barrier Reef, we’ll need to be able to scale up these techniques. </p>
<p>To date, coral restoration and adaptation has been done at relatively small scale and high cost. Coral breeding has largely been done by hand, in small laboratory aquarium facilities, which is slow and expensive. </p>
<p>But this is changing. At our site in Townsville, we’ve made advances in coral aquaculture with the potential to significantly boost production rates while cutting costs. </p>
<p>How do you produce heat-tolerant corals at scale? Settle selected baby corals on small tabs in modular sheets. Separate the individual tabs, each now home to a thriving baby coral, and attach them to special fist-sized structures designed to protect the babies in the ocean. This greatly increases their survival rate once on the reef. </p>
<p>We’re trialling these technologies by depositing these structures in carefully chosen places along the reef where they can grow and, eventually, reproduce. As we scale up production, we will be able to deliver large numbers of structures without requiring divers, by using boats or robots. </p>
<p>These technologies mean we can increasingly automate coral rearing. At present, these techniques are available for around 50 coral species on the Great Barrier Reef. </p>
<p>Making sure human systems work well is also vital. To ensure heat-resistant baby coral thrive, we have to have good ecological models and decision-making processes which take economic, social, and environmental factors into account. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Woppaburra Traditional Custodians" src="https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542087/original/file-20230810-19-i6hwim.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">Science and traditional knowledge can complement each other.</span>
<span class="attribution"><span class="source">AIMS</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Success will also depend on meaningful partnerships with Traditional Owners. Combining conventional science and traditional knowledge can bring fresh insights. Marine management of Groote Eylandt in Australia’s north now uses <a href="https://www.frontiersin.org/articles/10.3389/fmars.2020.00716/full">maps produced</a> by scientists working with Anindilyakwa people to combine local knowledge, in-water surveys and satellite data. </p>
<p>As we move towards large-scale restoration and adaptation, Australia’s First Nations rangers could provide a vital community-based workforce to deliver a new suite of management and conservation activities, especially in remote regions. Traditional Owners could also play important roles in <a href="https://www.science.org/doi/10.1126/science.1232310#:%7E:text=Coral%20reef%20recovery%20from%20major,highly%20vulnerable%20to%20catastrophic%20disturbance.">monitoring progress</a>. </p>
<p>Until recently, conservation efforts were aimed at protecting ecosystems from damage and limiting access, allowing natural systems to bounce back. But in the era of global heating, this is no longer enough. Disruptions are coming faster, challenging nature’s resilience. </p>
<p>We have to help. Time is short and there is much to do.</p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/is-the-great-barrier-reef-reviving-or-dying-heres-whats-happening-beyond-the-headlines-210558">Is the Great Barrier Reef reviving – or dying? Here's what's happening beyond the headlines</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/209388/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Line K Bay receives research funding from the Reef Restoration and Adaptation Program, the Paul G Allen Family Foundation, BHP and Revive & Restore</span></em></p><p class="fine-print"><em><span>Paul Hardisty 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>We used to focus just on protection of vital ecosystems like the reef. But as climate change and other threats accelerate, we need to actively help nature get ready for the heat.Paul Hardisty, CEO, Australian Institute of Marine ScienceLine K Bay, Research Program Director, Australian Institute of Marine ScienceLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2109742023-08-09T12:32:33Z2023-08-09T12:32:33ZThe heroic effort to save Florida’s coral reef from extreme ocean heat as corals bleach across the Caribbean<figure><img src="https://images.theconversation.com/files/541348/original/file-20230806-200746-p7nvgb.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C828%2C580&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Elkhorn coral fragments rescued from overheating ocean nurseries sit in cooler water at Keys Marine Laboratory.</span> <span class="attribution"><a class="source" href="https://www.climate.gov/news-features/event-tracker/noaa-and-partners-race-rescue-remaining-florida-corals-historic-ocean">NOAA</a></span></figcaption></figure><p>Armed with scrub brushes, <a href="https://divingwithapurpose.org/">young scuba divers</a> took to the waters of Florida’s Alligator Reef in late July to try to help corals struggling to survive 2023’s extraordinary marine heat wave. They carefully scraped away harmful algae and predators impinging on staghorn fragments, under the supervision and training of interns from <a href="https://icareaboutcoral.org">Islamorada Conservation and Restoration Education</a>, or I.CARE.</p>
<p>Normally, I.CARE’s volunteer divers would be transplanting corals to waters off the Florida Keys this time of year, as part of a <a href="https://www.fisheries.noaa.gov/southeast/habitat-conservation/restoring-seven-iconic-reefs-mission-recover-coral-reefs-florida-keys">national effort to restore the Florida Reef</a>. But this year, everything is going in reverse.</p>
<p>As water temperatures spiked in the Florida Keys, scientists from universities, coral reef restoration groups and government agencies launched <a href="https://www.pbs.org/newshour/show/coral-reefs-off-coast-of-florida-bleached-as-water-temperatures-top-100-degrees-fahrenheit">a heroic effort</a> to save the corals. Divers have been in the water every day, <a href="https://www.pbs.org/newshour/show/coral-reefs-off-coast-of-florida-bleached-as-water-temperatures-top-100-degrees-fahrenheit?fbclid=IwAR1fhi0rBA2WrtlmBNFgAK5cIHqOcQDBo3dSUx_RS1XOFUvHoBHFoYwee7E">collecting thousands of corals</a> from ocean nurseries along the Florida Keys reef tract and moving them to cooler water and into giant tanks on land. </p>
<p>Marine scientist Ken Nedimyer and his team at <a href="https://reefrenewalusa.org/">Reef Renewal USA</a> moved an entire <a href="https://www.semanticscholar.org/paper/Coral-tree-nursery%C2%A9%3A-an-innovative-approach-to-in-Nedimyer-Gaines/02e1e8a6253b9a894edf92cf3131e0aaf56bc02c">coral tree nursery</a> from shallow waters off Tavernier to an area 60 feet deep and <a href="https://www.nytimes.com/2023/07/31/climate/coral-reefs-heat-florida-ocean-temperatures.html">2 degrees Fahrenheit (1.1 Celsius) cooler</a>. Even there, temperatures were running about 85 to 86 F (30 C). </p>
<figure class="align-center ">
<img alt="A diver with a collection bag retrieves corals from a stand underwater." src="https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=768&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=768&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=768&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=965&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=965&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541398/original/file-20230807-20-ec3q71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=965&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Marine scientist Ken Nedimyer collects still-healthy elkhorn coral fragments for moving. The tree structure keeps the corals free of harmful algae.</span>
<span class="attribution"><a class="source" href="https://reefrenewalusa.org/beat-the-heat/">Reef Renewal USA</a></span>
</figcaption>
</figure>
<p>Their efforts are part of an emergency response on a scale never before seen in Florida.</p>
<p>The <a href="https://floridascoralreef.org/">Florida Reef</a> – a nearly 350-mile arc along the Florida Keys that is crucial to fish habitat, coastal storm protection and <a href="https://sanctuaries.noaa.gov/science/socioeconomic/factsheets/floridakeys.html">the local economy</a> – began experiencing <a href="https://www.climate.gov/news-features/event-tracker/noaa-and-partners-race-rescue-remaining-florida-corals-historic-ocean">record-hot ocean temperatures</a> in June 2023, weeks earlier than expected. The continuing heat has triggered <a href="https://www.aoml.noaa.gov/cheeca-rocks-reef-completely-bleached/">widespread coral bleaching</a> off Florida in particular, but also beyond.</p>
<p>By mid-August, coral bleaching <a href="https://research.noaa.gov/wp-content/uploads/2023/08/NOAA-Deep-Dive-Coral-Briefing.pptx-5.pdf%22%22">had been reported</a> in the Bahamas, Cuba, Mexico, Belize, El Salvador, Costa Rica, Panama and Colombia, as well as Puerto Rico and the U.S. Virgin Islands. This is particularly devastating because some of the healthiest remaining coral reefs are in the <a href="https://www.iucn.org/sites/default/files/import/downloads/caribbean_coral_reefs___status_report_1970_2012.pdf">southern Caribbean</a>. Scientists worry they may be seeing the sixth mass bleaching of Caribbean corals since 1995 and the <a href="https://www.agrra.org/coral-bleaching">third within the past 12 years</a>, and the heat is <a href="https://www.epa.gov/climate-indicators/climate-change-indicators-sea-surface-temperature">likely to continue</a>.</p>
<figure class="align-center ">
<img alt="A white coral mound with groves and a tag on the side." src="https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541480/original/file-20230807-6265-nodvp1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A bleached mound of coral at the Cheeca Rocks monitoring site in the Florida Keys National Marine Sanctuary that had been previously tagged shows the coral skeleton.</span>
<span class="attribution"><a class="source" href="https://www.aoml.noaa.gov/cheeca-rocks-reef-completely-bleached/">NOAA AOML</a></span>
</figcaption>
</figure>
<p>While corals can recover from mass bleaching events, long periods of high heat can leave them weak and vulnerable to disease that can <a href="https://www.surfrider.org/news/soaring-ocean-temperatures-trigger-coral-bleaching-event-in-south-florida">ultimately kill them</a>.</p>
<p>That’s what scientists and volunteers have been scrambling to avoid. </p>
<h2>The heartbeat of the reef</h2>
<p>The Florida Reef has struggled for years under the pressure of overfishing, disease, storms and global warming that have decimated its live corals. </p>
<p>A massive <a href="https://www.fisheries.noaa.gov/southeast/habitat-conservation/restoring-seven-iconic-reefs-mission-recover-coral-reefs-florida-keys">coral restoration effort</a> – the National Oceanic and Atmospheric Administration’s Mission: Iconic Reef – has been underway since 2019 to restore the reef with transplanted corals, particularly those most resilient to the rising temperatures. But even the hardiest coral transplants are now at risk.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/PDJXgxHs7Ak?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Divers involved in NOAA’s Mission: Iconic Reef show how staghorn and elkhorn corals are being transplanted to help the Florida Reef recover.</span></figcaption>
</figure>
<p>Reef-building corals are the foundation species of shallow tropical waters due to their unique symbiotic relationship with microscopic algae in their tissues.</p>
<p>During the day, these algae photosynthesize, producing both food and oxygen for the coral animal. At night, coral polyps feed on plankton, providing nutrients for their algae. The result of this symbiotic relationship is the coral’s ability to build a calcium carbonate skeleton and reefs that <a href="https://www.fisheries.noaa.gov/corals#overview">support nearly 25% of all marine life</a>.</p>
<p>Unfortunately, corals are very temperature sensitive, and the extreme ocean heat off South Florida, with <a href="https://www.miamiherald.com/news/local/environment/climate-change/article277828813.html">some reef areas reaching temperatures in the 90s,</a> has put them under extraordinary stress.</p>
<figure class="align-center ">
<img alt="Two images show a colorful coral with fish swimming over it and the same coral bleached, looking ghostly white." src="https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541343/original/file-20230806-225752-p7nvgb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A boulder brain coral, <em>Colpophyllia natans</em>, before and after bleaching during the 2014 marine heat wave in the Florida Keys.</span>
<span class="attribution"><span class="source">Photos by Michael Childress and Kylie Smith</span></span>
</figcaption>
</figure>
<p>When corals get too hot, they expel their symbiotic algae. The corals appear white – bleached – because their carbonate skeleton shows through their clear tissue that lack any colorful algal cells.</p>
<p>Corals <a href="https://oceanservice.noaa.gov/facts/coral_bleach.html">can recover</a> new algal symbionts if water conditions return to normal within a few weeks. However, the increase in global temperatures due to the effects of greenhouse gas emissions from human activities is causing <a href="https://doi.org/10.1038/nature22901">longer and more frequent</a> periods of coral bleaching worldwide, leading to <a href="https://www.hawaii.edu/news/2022/10/11/coral-reefs-climate-change-threat/">concerns for the future</a> of coral reefs.</p>
<h2>A MASH unit for corals</h2>
<p>This year, the Florida Keys reached an alert level 2, indicating extreme risk of bleaching, about six weeks earlier than normal.</p>
<p>The early warnings and forecasts from <a href="https://coralreef.noaa.gov/">NOAA</a>’s <a href="https://coralreefwatch.noaa.gov/">Coral Reef Watch Network</a> gave scientists time to begin preparing labs and equipment, track the locations and intensity of the growing marine heat and, importantly, recruit volunteers.</p>
<figure class="align-center ">
<img alt="Two charts show ocean temperatures far above normal." src="https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544101/original/file-20230822-28-k0267g.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">This year’s maximum sea surface temperature (top chart, black bar) and degree heating weeks (lower chart, black bar), a measure of accumulated heat stress, have been the highest since record-keeping began.</span>
<span class="attribution"><a class="source" href="https://coralreefwatch.noaa.gov/data/vs/ts_figures/ts_multi_year/vs_ts_multiyr_florida_keys.png">NOAA</a></span>
</figcaption>
</figure>
<p>At the <a href="https://www.fio.usf.edu/keys-marine-lab/">Keys Marine Laboratory</a>, scientists and trained volunteers have dropped off thousands of coral fragments collected from heat-threatened offshore nurseries. Director Cindy Lewis described the lab’s giant tanks as looking like “a <a href="https://en.wikipedia.org/wiki/Mobile_Army_Surgical_Hospital">MASH unit</a> for corals.”</p>
<p>Volunteers there and at other labs across Florida will hand-feed the tiny creatures to keep them alive until the Florida waters cool again and they can be returned to the ocean and eventually transplanted onto the reef.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map shows high heat off Florida and the Bahamas, as well as in the tropical Pacific along the equator, where warm water indicates El Nino conditions." src="https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=505&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=505&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=505&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=634&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=634&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543388/original/file-20230818-19-i65j2j.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=634&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Degree heating weeks is a measure of accumulated heat stress over the previous 12 weeks. At 4-degree Celsius-weeks (7.2 Fahrenheit-weeks), coral bleaching is expected. Above 8 C-weeks (14.4 F-weeks), significant bleaching and mortality are expected to begin.</span>
<span class="attribution"><a class="source" href="https://coralreefwatch.noaa.gov/product/5km/index_5km_dhw.php">NOAA Coral Reef Watch</a></span>
</figcaption>
</figure>
<h2>Protecting corals still in the ocean</h2>
<p><a href="https://icareaboutcoral.org">I.CARE</a> launched another type of emergency response. </p>
<p>I.CARE co-founder Kylie Smith, a coral reef ecologist and a former student of mine in marine sciences, discovered a few years ago that coral transplants with large amounts of fleshy algae around them were <a href="https://doi.org/10.1007/s00338-019-01823-7">more likely to bleach</a> during times of elevated temperature. Removing that algae may give corals a better chance of survival.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two photos show young people being trained to work with coral fragments and then on a dive clearing algae from around corals." src="https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=299&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=299&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=299&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=375&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=375&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541347/original/file-20230806-213730-ugyy8l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=375&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Youth members of Diving With a Purpose attend a training session and coral maintenance dive with the Islamorada Conservation and Restoration Education team in Islamorada, Fla.</span>
<span class="attribution"><span class="source">I.CARE</span></span>
</figcaption>
</figure>
<p>Smith’s group typically works with local dive operators to train recreational divers to assist in transplanting and maintaining coral fragments in an effort to restore the reefs of Islamorada. In summer 2023, I.CARE has been training volunteers, like the young divers from <a href="https://divingwithapurpose.org/">Diving with a Purpose</a>, to remove algae and coral predators, such as <a href="https://www.marinespecies.org/aphia.php?p=taxdetails&id=419934">coral-eating snails</a> and <a href="https://www.marinebio.org/species/bearded-fireworms/hermodice-carunculata">fireworms</a>, to help boost the corals’ chances of survival.</p>
<h2>Monitoring for corals at risk</h2>
<p>To help spot corals in trouble, volunteer divers are also being trained as reef observers through Mote Marine Lab’s <a href="https://mote.org/research/program/coral-reef-science-monitoring/bleachwatch">BleachWatch</a> program.</p>
<p>Scuba divers have long been attracted to the reefs of the Florida Keys for their beauty and accessibility. The lab is training them to recognize bleached, diseased and dead corals of different species and then use an online portal to submit bleach reports across the entire Florida Reef. </p>
<p>The more eyes on the reef, the more accurate the maps showing the areas of greatest bleaching concern.</p>
<figure class="align-center ">
<img alt="A diver looks at a mounds of bleached corals" src="https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541346/original/file-20230806-96278-k8vdyv.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ian Enochs, a research ecologist and lead of NOAA’s Atlantic Oceanographic and Meteorological Lab Coral Program, found that every coral in the Cheeca Rocks area had bleached by Aug. 1, 2023.</span>
<span class="attribution"><a class="source" href="https://www.aoml.noaa.gov/cheeca-rocks-reef-completely-bleached/">NOAA AOML</a></span>
</figcaption>
</figure>
<h2>Rebuilding the reef</h2>
<p>While the marine heat wave in the Keys will inevitably kill some corals, many more will survive.</p>
<p>Through <a href="https://link.springer.com/article/10.1007/s00338-020-01948-0">careful analysis</a> of the species, genotypes and reef locations experiencing bleaching, scientists and practitioners are learning valuable information as they work to protect and rebuild a more resilient coral reef for the future.</p>
<p>That is what gives hope to Smith, Lewis, Nedimyer and hundreds of others who believe this coral reef is worth saving. Volunteers are crucial to the effort, whether they’re helping with coral reef maintenance, reporting bleaching or raising the awareness of what is at stake if humanity fails to stop warming the planet.</p>
<p><em>This article was updated Aug. 22, 2023, to correct the description of the impact of degree-heating weeks accompanying two charts. At 4-degree Celsius-weeks, coral bleaching is expected. Above 8 C-weeks, signficant bleaching and mortality are expected.</em></p><img src="https://counter.theconversation.com/content/210974/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Childress 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>Ocean temperatures have hit record highs off the Florida Keys. Scientists and volunteer divers are racing to save these valuable creatures.Michael Childress, Associate Professor of Biological Sciences & Environmental Conservation, Clemson UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2105582023-08-09T02:21:15Z2023-08-09T02:21:15ZIs the Great Barrier Reef reviving – or dying? Here’s what’s happening beyond the headlines<p>The Great Barrier Reef is not dead. Nor is it in good health. The truth is complex. To understand what’s going on takes more than a headline. </p>
<p>For the last 37 years, our organisation has monitored the health of the world’s largest reef. Each year, we add our findings to our dataset, the Reef’s longest running and largest coverage. This lets us produce annual updates for the northern, central and southern regions of the Reef. That makes us perhaps the team best qualified to answer the question many people have – how is the Reef going? </p>
<p>Released today, this <a href="https://www.aims.gov.au/monitoring-great-barrier-reef/gbr-condition-summary-2022-23">year’s update</a> paints a complex picture. It wasn’t long ago the Great Barrier Reef was reeling from successive disturbances, ranging from marine heatwaves and coral bleaching to crown-of-thorns starfish outbreaks and cyclone damage, with widespread death of many corals especially during the heatwaves of 2016 and 2017.</p>
<p>Since then, the Reef has rebounded. Generally cooler La Niña conditions mean hard corals have recovered significant ground, regrowing from very low levels after a decade of cumulative disturbances to record high levels in 2022 across two-thirds of the reef. </p>
<p>The Reef has shown an impressive ability to recover from widespread disturbances, when it gets a chance – it’s not all just bleaching and death. But it’s also true we’re heading towards a future where hotter water temperatures will <a href="https://www.nature.com/articles/srep39666">likely cause bleaching</a> every year, along with ongoing threats of cyclones and coral-eating starfish. Recovery requires reprieve – and those opportunities will diminish as climate change progresses.</p>
<p>Last year, for instance, parts of the Reef <a href="https://www.abc.net.au/news/2023-08-09/mass-coral-bleaching-halts-great-barrier-reef-recovery/102706194">experienced bleaching</a> in the middle of La Niña – the first time that’s happened on record. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="barrier reef coral trends 2023" src="https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541837/original/file-20230809-17-7xg9in.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trends in hard coral cover across the Great Barrier Reef’s three sections from 1986-2023.</span>
<span class="attribution"><span class="source">AIMS</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>What’s happening on the Reef?</h2>
<p>To take the pulse of the Great Barrier Reef, one indicator we use is hard coral cover. It’s a widely used, robust indicator of reef health, but it doesn’t tell the whole story. We also collect detailed data on coral and fish populations, diversity, structural complexity, and abundance of juvenile corals. And we take digital photographs and convert them into 3D photogrammetry models so we can analyse what’s happening in more depth than ever before.</p>
<p>Here’s what our analysis shows. </p>
<p>Over the last few years, the Reef was mostly in La Niña conditions. That gave the hard-hit northern and central parts of the reef a chance to begin recovery. Many reefs had a high proportion of <em>Acropora</em> corals, of which the best known are the staghorn and plate corals. These species have been a vital part of the reef over 37 years of monitoring – and probably for millennia.</p>
<p>These corals are the most common on many reefs, and grow fast. Because of that, they tend to dominate trends in hard coral cover.</p>
<figure class="align-center ">
<img alt="High cover of Acropora corals on the southern GBR." src="https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541826/original/file-20230808-31-49o8nw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This reef in the southern section has a high cover of Acropora corals.</span>
<span class="attribution"><span class="source">AIMS, CC BY-ND</span></span>
</figcaption>
</figure> <p></p>
<p>Does this mean the Great Barrier Reef’s recovery in 2022 relied on “weedy” corals which are taking over? Yes and no. The natural ecological niche of <em>Acropora</em> corals has always been to rapidly fill empty space, which means it tends to dominate trends in coral recovery. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/record-coral-cover-doesnt-necessarily-mean-the-great-barrier-reef-is-in-good-health-despite-what-you-may-have-heard-188233">Record coral cover doesn't necessarily mean the Great Barrier Reef is in good health (despite what you may have heard)</a>
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</em>
</p>
<hr>
<p>Again, the story is more complicated than the headlines. Some reefs have recovered strongly, some very little. Some reefs are recovering with less <em>Acropora</em> than before, some with more. Each reef is charting its own course on the journey from impact to recovery and back again. </p>
<p>Overall, the record high hard coral cover seen last year was welcome news, representing recovery across much of the Reef in the absence of common coral killers. </p>
<h2>But what about recent heating?</h2>
<p>This year, the rapid coral rebound paused. Some reefs continued to recover, but these were offset by others which lost coral. Coral loss came from effects of the 2022 bleaching event in northern and central regions, crown-of-thorns starfish predation in the northern and southern regions, damage from Tropical Cyclone Tiffany in the north and coral disease in some areas of the south. </p>
<p>The picture is complex. Recovery here, fresh losses there.</p>
<p>While the recovery we reported last year was welcome news, there are challenges ahead. The spectre of global annual coral bleaching will soon become a reality. </p>
<figure class="align-center ">
<img alt="Bleached corals on the central Great Barrier Reef during the summer of 2022" src="https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541819/original/file-20230808-25-fxdksi.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">Coral bleaching on on the central Great Barrier Reef during the summer of 2022.</span>
<span class="attribution"><span class="source">AIMS, CC BY-ND</span></span>
</figcaption>
</figure>
<p>Right now, marine heatwaves are <a href="https://www.washingtonpost.com/weather/2023/06/23/ocean-heatwave-northatlantic-uk-climate/">sweeping through</a> ocean basins in the northern hemisphere. Sea surface temperatures are far above long term averages. </p>
<p>At least eight countries are reporting coral bleaching, including <a href="https://www.theguardian.com/environment/2023/aug/04/florida-coral-bleached-ocean-heat">the United States</a> and Belize. This summer, it looks likely we’ll see our first El Niño on the Great Barrier Reef since 2016, bringing higher sea surface temperatures. That last El Niño – coupled with global heating – was the direct cause of the 2016–17 mass bleaching and mass death of corals.</p>
<p>The prognosis is, in short, extremely concerning. Yes, the Reef has rebounded beyond our expectations. But now the heat is back on. If we get mass bleaching like 2016 – or even worse – it could undo all the recent recovery. </p>
<p><hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/out-of-danger-because-the-un-said-so-hardly-the-barrier-reef-is-still-in-hot-water-210787">Out of danger because the UN said so? Hardly – the Barrier Reef is still in hot water</a>
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</p>
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</p><img src="https://counter.theconversation.com/content/210558/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Emslie works for the Australian Institute of Marine Science which receives funding from the Australian Government to conduct the Long-Term Monitoring Program.
AIMS also receives external funding from a number of sources including but not limited to the Australian Government's Reef Trust Partnership, Woodside Energy, Santos Ltd, BHP, Carnegie Institution for Science, The European Union’s Marie Skłodowska-Curie Actions, Taronga Conservation Society Australia, Taronga Foundation, Smithsonian Conservation Biology Institute, Accenture and the Allen Coral Atlas.
</span></em></p><p class="fine-print"><em><span>Daniela Ceccarelli works for the Australian Institute of Marine Science which receives funding from the Australian Government to conduct the Long-Term Monitoring Program.
</span></em></p><p class="fine-print"><em><span>David Wachenfeld works for the Australian Institute of Marine Science which receives funding from the Australian Government to conduct the Long-Term Monitoring Program. </span></em></p>In recent years, the Barrier Reef has had a reprieve – and coral has regrown strongly. But now the reprieve looks to be over and the heat is back onMike Emslie, Senior Research Scientist, Australian Institute of Marine ScienceDaniela Ceccarelli, Research fellow, Australian Institute of Marine ScienceDavid Wachenfeld, Research Program Director- Reef Ecology and Monitoring, Australian Institute of Marine ScienceLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2107872023-08-01T06:30:55Z2023-08-01T06:30:55ZOut of danger because the UN said so? Hardly – the Barrier Reef is still in hot water<figure><img src="https://images.theconversation.com/files/540330/original/file-20230801-198210-3bop0q.jpg?ixlib=rb-1.1.0&rect=0%2C162%2C5184%2C3282&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>Today is a good day to be Environment Minister Tanya Plibersek. UNESCO, the United Nations body expected to vote on whether to list the Great Barrier Reef as “in danger”, instead <a href="https://whc.unesco.org/archive/2023/whc23-45com-7B.Add-en.pdf#page26">deferred the decision</a> for another year. This, an insider told French newspaper Le Monde, was largely due to the change in approach between the former Coalition government and Labor. </p>
<p>“It’s a bit like night and day,” the insider said – which was promptly included in Plibersek’s <a href="https://minister.dcceew.gov.au/plibersek/media-releases/un-recognises-australian-government-action-protect-great-barrier-reef">media release</a>.</p>
<p>So, it’s a good day for the government. But is it a good day for the reef? No. The longstanding threats to the world’s largest coral ecosystem are still there, from agricultural runoff, to shipping pollution, to fisheries, although we have seen improvement in areas such as <a href="https://reportcard.reefplan.qld.gov.au">water quality</a>.</p>
<p>But any incremental improvement will be for naught if we don’t respond to the big one – climate change – with the necessary urgency. This year has seen <a href="https://www.theguardian.com/environment/2023/jul/05/tuesday-was-worlds-hottest-day-on-record-breaking-mondays-record">record-breaking heat</a> and extreme weather, with <a href="https://www.bbc.com/future/article/20230720-theres-a-heatwave-in-the-sea-and-scientists-are-worried">intense heating</a> of the oceans during the northern summer. These intense marine heatwaves have devastated efforts to <a href="https://www.local10.com/weather/2023/07/28/um-rescuers-are-urgently-trying-to-save-corals-from-what-could-be-devastating-for-oceans/">regrow or protect</a> coral in places like Florida. And our own summer is just around the corner. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/seriously-ugly-heres-how-australia-will-look-if-the-world-heats-by-3-c-this-century-157875">Seriously ugly: here's how Australia will look if the world heats by 3°C this century</a>
</strong>
</em>
</p>
<hr>
<p>It is not hyperbole to say the next two years are likely to be very bad for the Great Barrier Reef. It’s <a href="https://www.theguardian.com/environment/2023/jul/22/marine-heatwave-in-north-east-queensland-sets-off-alarm-over-health-of-great-barrier-reef">already enduring</a> a winter marine heatwave. Background warming primes the reef for mass coral bleaching and death. We’ve already experienced this in 2016-17, which brought <a href="https://link.springer.com/article/10.1007/s00338-018-01749-6">back-to-back</a> global mass coral bleaching and mortality events including on the Great Barrier Reef. We can expect more as global temperatures continue to soar. </p>
<p>While the government may congratulate itself on not being the previous one, it’s nowhere near enough. We’re facing D-Day for the reef, as for many other ecosystems. Incrementalism and politics as usual are simply not going to be enough. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1686102788005408769"}"></div></p>
<h2>What has the government done for the reef to date?</h2>
<p>To its credit, Labor has made some marginal improvements to the Great Barrier Reef’s prospects. The <a href="https://minister.dcceew.gov.au/plibersek/media-releases/un-recognises-australian-government-action-protect-great-barrier-reef">list</a> includes: legislating net zero greenhouse emissions, with a 43% cut within seven years; improving water quality with revegetation projects and work to reduce soil erosion; and <a href="https://www.theguardian.com/environment/2023/jun/05/conservationists-welcome-gillnet-fishing-ban-in-great-barrier-reef-world-heritage-area">ending gillnet use</a> in the Great Barrier Reef Marine Park by 2027.</p>
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<strong>
Read more:
<a href="https://theconversation.com/warm-is-the-new-norm-for-the-great-barrier-reef-and-a-likely-el-nino-raises-red-flags-206750">Warm is the new norm for the Great Barrier Reef – and a likely El Niño raises red flags</a>
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<p>For at least a century, cattle, sugarcane and other farmers have relied on rivers to take animal waste and fertiliser runoff away from their properties. In much of Queensland, that means the runoff heads for the Great Barrier Reef instead. We did see some improvement under the Coalition government, which put A$443 million into trying to <a href="https://www.abc.net.au/news/2023-04-22/remember-that-record-funding-for-the-great-barrier-reef/102252268">solve the issue</a>. Labor has put in a <a href="https://minister.dcceew.gov.au/plibersek/media-releases/joint-media-release-improving-water-quality-protect-great-barrier-reef">further $150 million</a>. But the water quality problem is still <a href="https://www.reefplan.qld.gov.au/tracking-progress/reef-report-card/2020">not solved</a>. </p>
<p>Ending gillnet use in the marine park is also welcome, given these nets can and do catch and kill sharks, dugongs and turtles. But challenging though these issues are, they pale in comparison to climate change. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="barrier reef" src="https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540364/original/file-20230801-25-vs9gal.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">Goldilocks zone: coral likes its water warm – but not too warm.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Tinkering while the reef burns</h2>
<p>When coral is exposed to warmer water than it has evolved to tolerate, it turns white (bleaches) – expelling its symbiotic algae. If the water stays too hot for too long, the corals simply die en masse. </p>
<p>You might have seen the <a href="https://www.whoi.edu/oceanus/feature/is-the-great-barrier-reef-making-a-comeback/">positive reports</a> on coral regrowth during the three recent cooler La Niña years and wonder what the issue is. Isn’t the reef resilient? </p>
<p>Yes – to a point. But after that point, the coral communities collapse. The world is having its <a href="https://www.nytimes.com/2023/07/06/climate/climate-change-record-heat.html">hottest days on record</a>. Coupled with a <a href="https://theconversation.com/its-official-australia-is-set-for-a-hot-dry-el-nino-heres-what-that-means-for-our-flammable-continent-209126">likely El Niño</a>, the reef will likely face the hottest waters yet.</p>
<p>That’s because we still haven’t tackled the root cause. Greenhouse gas emissions are <a href="https://www.theguardian.com/environment/2023/jun/08/global-greenhouse-gas-emissions-at-all-time-high-study-finds">still going up</a>. Year on year, we’re trapping more heat, of which 90% goes <a href="https://theconversation.com/two-trillion-tonnes-of-greenhouse-gases-25-billion-nukes-of-heat-are-we-pushing-earth-out-of-the-goldilocks-zone-202619">into the oceans</a>. Antarctic sea ice is <a href="https://www.sciencealert.com/6-4-sigma-event-antarctic-sea-ice-hits-lowest-point-since-official-records-began">not reforming</a> as it should after last summer. Coral restoration efforts in the United States had to <a href="https://www.nytimes.com/2023/07/31/climate/coral-reefs-heat-florida-ocean-temperatures.html">literally pull</a> their baby corals out of the sea to try to keep them alive, as the water was too hot to live in. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/two-trillion-tonnes-of-greenhouse-gases-25-billion-nukes-of-heat-are-we-pushing-earth-out-of-the-goldilocks-zone-202619">Two trillion tonnes of greenhouse gases, 25 billion nukes of heat: are we pushing Earth out of the Goldilocks zone?</a>
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<p>The North Atlantic Ocean is <a href="https://www.washingtonpost.com/weather/2023/07/28/ocean-temperature-maps-heat-records/">far warmer</a> than it should be, amid a record-breaking northern summer. After the equinox next month, it will be our turn to face the summer sun once more. </p>
<p>Is the Great Barrier Reef in danger? Of course it is. We should not pretend things are normal and can be handled routinely. This year, we’re beginning to see the full force of what the climate crisis will bring. We have clearly underestimated the climate’s sensitivity to rising carbon dioxide levels, and the <a href="https://www.publish.csiro.au/MF/MF99078">gloomy predictions</a> I made more than 20 years ago are looking positively optimistic. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1686120431298961409"}"></div></p>
<p>And still we fail to face up to the fact that the Great Barrier Reef is dying. We thought we might have had decades but it may be just years. Before 1980, no mass bleaching had <a href="https://www.publish.csiro.au/MF/MF99078">ever been recorded</a>. Since then it has only become more common. </p>
<p>Incremental efforts to save the reef, such as looking for <a href="https://www.smithsonianmag.com/science-nature/at-least-one-species-of-pacific-coral-may-thrive-in-warmer-waters-180982561/">heat-tolerant “supercorals”</a>, or replanting baby coral, now look unlikely to work. We don’t have decades or the capacity to find and cultivate resilient corals at scale. And we certainly do not have the <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/15-1077">massive funding required</a> to replant even a small coral reef. </p>
<p>For people like us who work in the field, it is a devastating time. I now know the feeling of having a broken heart. The pace and intensity of climate change risks rendering all our efforts over the years null and void. It’s almost impossible to look directly at what this will mean for this immense living assemblage, which first began growing more than 600,000 years ago along the Australian east coast. </p>
<p>Giving the government more time to show the reef is improving seems like a fool’s errand. Time is precisely what we don’t have. </p>
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Read more:
<a href="https://theconversation.com/corals-are-starting-to-bleach-as-global-ocean-temperatures-hit-record-highs-209770">Corals are starting to bleach as global ocean temperatures hit record highs</a>
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<img src="https://counter.theconversation.com/content/210787/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ove Hoegh-Guldberg is affiliated with the Great Barrier Reef Foundation and the ARC Centre for Excellence for Coral Reef Studies.
</span></em></p>Incrementalism and politics as usual cannot save the Barrier Reef from the largest threat it faces – the heat ramping up from climate changeOve Hoegh-Guldberg, Professor, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2103722023-07-27T01:28:14Z2023-07-27T01:28:14ZThrough the magnifying glass: how cutting-edge technology is helping scientists understand baby corals<p>New photographic technology has allowed scientists to dive beneath the ocean’s surface and peer into the hidden world of baby corals, to learn how these tiny organisms survive and grow in their crucial first year of life.</p>
<p>In a study <a href="https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/2041-210X.14175">just published</a>, researchers from Southern Cross University and CSIRO describe how advanced imaging techniques offer new ways to monitor baby corals. </p>
<p>Corals provide vital habitat for a large variety of marine life. So it’s useful to better understand how baby corals select and attach to reefs, establish themselves and grow into adult corals.</p>
<p>This knowledge is particularly important if we want to help reefs recover from devastating events such as mass bleaching and cyclones.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539177/original/file-20230725-23-wrtgjj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&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">3D animation of a 6-month old coral recruit approximately 2.1 mm in size.</span>
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</figure>
<h2>The secret life of corals</h2>
<p>The life of a coral begins in an annual, synchronised spawning event. Coral colonies release millions of tiny eggs and sperm into the water at the same time. They all rise to the surface where the eggs are fertilised, developing into embryos and then later, into larvae.</p>
<p>Over days or weeks, the millions of larvae disperse with ocean currents. If things go according to nature’s plan, the larvae eventually fall through the water, attach to a reef and grow into adult corals. This process is known as coral “recruitment”.</p>
<p>In healthy coral reefs, this recruitment occurs naturally. But as coral reefs become more degraded – such as through coral bleaching brought on by climate change – <a href="https://www.nature.com/articles/s41586-019-1081-y">fewer coral larvae are produced</a>. This often means recruitment slows down or stops, and natural recovery weakens.</p>
<p>Scientists are working on ways to ensure coral larvae attach to and grow on reefs. This includes collecting coral spawn from the ocean, rearing embryos in floating nurseries and <a href="https://www.nature.com/articles/s41598-017-14546-y">releasing larvae onto damaged reefs</a>.</p>
<p>Coral larvae are less than one millimetre in size, so recruitment occurs on a tiny scale, invisible to the human eye. To better understand the process, researchers traditionally <a href="https://doi.org/10.1007/s003380000081">attach artificial plates</a> to the reef. Once corals have established themselves, the plates are taken back to the lab to be inspected under a microscope.</p>
<p>This method can provide valuable insights, but it does not replicate the natural reef environment. That’s where our research comes in. Essentially, we brought the lab to the reef.</p>
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Read more:
<a href="https://theconversation.com/safe-havens-for-coral-reefs-will-be-almost-non-existent-at-1-5-c-of-global-warming-new-study-176084">Safe havens for coral reefs will be almost non-existent at 1.5°C of global warming – new study</a>
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<figure class="align-center ">
<img alt="bleached coral reef" src="https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539452/original/file-20230726-23-png2p0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Mass bleaching and other damaging events is limiting the establishment of baby corals.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<h2>Capturing the reef in incredible 3D detail</h2>
<p>Our new study explores the development and application of an innovative imaging approach known as underwater “macrophotogrammetry”.</p>
<p>The technology combines <a href="https://www.uwphotographyguide.com/macro-underwater-photography">macrophotography</a> – photographing small objects close-up, at very high resolution – and <a href="https://www.sciencedirect.com/science/article/pii/S0169534721001944?via%3Dihub">photogrammetry</a> – taking measurements from photos. In this case, we used photogrammetry to “stitch” photos together to recreate three-dimensional models, such as the one below.</p>
<p>The three round objects in the model are “targets” we placed to help the software stitch the photos together. Look closely, and you’ll see a nail head to the left of each target. To give you an idea of the scale of the model, the nail head is 2.8mm in diameter.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539176/original/file-20230725-25-r3sdrj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A 3D animation of approximately 400 cm² of the reef at micrometre resolution.</span>
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<p>Reef-scale photogrammetry can be a <a href="https://doi.org/10.1016/j.tree.2021.07.004">valuable tool</a> to track changes in coral cover and growth over time. However, it does not provide the detailed resolution needed to identify and observe tiny new corals. </p>
<p>Macrophotography provides this incredibly detailed scale. The coupling of the technologies also enables a comprehensive understanding of the entire ecosystem, from the smallest processes to the largest.</p>
<p>We conducted macrophotogrammetry surveys near Lizard Island on the Great Barrier Reef. We marked several 25cm x 25cm locations on the reef. We then captured hundreds of photographs taken at different angles using high-resolution cameras. </p>
<p>Photogrammetry software was used to process the photos, creating precise 3D models that represent the small sections of reef at very high resolution.</p>
<p>The models were examined to find where baby corals settle, to mark their location and measure their size. They reveal the complexity in the reef micro-structure, including tiny crevices, where coral larvae <a href="https://esajournals.onlinelibrary.wiley.com/doi/10.1890/15-0668.1">often settle</a>. </p>
<p>The models also reveal diverse micro-organisms such as small turf algae or invertebrates, <a href="https://www.nature.com/articles/s41598-020-59111-2">which interact with corals</a> during the recruitment process.</p>
<p>Macrophotogrammetry surveys can be conducted at the same reef locations over time. This allows us to monitor the survival and growth of baby corals, and observe changes in the organisms living near them. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/record-coral-cover-doesnt-necessarily-mean-the-great-barrier-reef-is-in-good-health-despite-what-you-may-have-heard-188233">Record coral cover doesn't necessarily mean the Great Barrier Reef is in good health (despite what you may have heard)</a>
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<figure class="align-center ">
<img alt="two divers in shallow water" src="https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539170/original/file-20230725-27-j2f1td.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">
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<span class="caption">The researchers monitor coral recruitment on a reef slope at Lizard Island.</span>
<span class="attribution"><span class="source">Lauren Hardiman CSIRO</span></span>
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<h2>Looking ahead</h2>
<p>Complementary techniques may increase the potential of macrophotogrammetry even further. For example, coral larvae can be <a href="https://doi.org/10.1371/journal.pbio.3001907">dyed various colours</a> before release, making them more visible when they swim to and settle on the reef. This could be captured in 3D models to allow even better tracking of larval restoration efforts.</p>
<p>The use of macrophotogrammetry will deepen our understandings of why some larvae settle and survive on reefs, and others do not. This knowledge can help support our efforts to improve the overall conservation and recovery of coral reefs. </p>
<p>Its application need not be limited to coral reef ecosystems. We are excited about the potential of the technology to drive marine research more broadly.</p>
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<strong>
Read more:
<a href="https://theconversation.com/thousands-of-photos-captured-by-everyday-australians-reveal-the-secrets-of-our-marine-life-as-oceans-warm-189231">Thousands of photos captured by everyday Australians reveal the secrets of our marine life as oceans warm</a>
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<img src="https://counter.theconversation.com/content/210372/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marine Gouezo works as a Postdoctoral researcher at Southern Cross University and CSIRO and is involved with the Moving Corals subprogram of the Reef Restoration and Adaptation Program, funded by the partnership between the Australian Government's Reef Trust and the Great Barrier Reef Foundation</span></em></p><p class="fine-print"><em><span>Christopher Doropoulos is a Research Scientist at CSIRO. He co-leads the Moving Corals and EcoRRAP Subprograms as part of the Reef Restoration and Adaptation Program (RRAP). RRAP is funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation.</span></em></p>This knowledge is particularly important if we want to help reefs recover devastating events such as mass bleaching and cyclones.Marine Gouezo, Postdoctoral research fellow, Southern Cross UniversityChristopher Doropoulos, Senior research scientist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2067502023-06-07T03:14:54Z2023-06-07T03:14:54ZWarm is the new norm for the Great Barrier Reef – and a likely El Niño raises red flags<p>The Bureau of Meteorology this week <a href="https://media.bom.gov.au/releases/1170/the-bureau-of-meteorology-issues-an-el-nino-alert/">declared</a> a 70% chance of an El Niño developing this year. This raises concern for the health of the Great Barrier Reef, which is under continuing threat from climate change.</p>
<p>Recent summers have shown the <a href="https://theconversation.com/5-major-heatwaves-in-30-years-have-turned-the-great-barrier-reef-into-a-bleached-checkerboard-170719">devastating damage</a> heat stress can wreak on the reef. We must act urgently to protect this underwater marvel – through this likely El Niño, and beyond.</p>
<p>We are coral reef and climate scientists, and policy experts. We’ve seen how the Great Barrier Reef is nearing its tipping point. After this point, it will become <a href="https://theconversation.com/adapt-move-or-die-repeated-coral-bleaching-leaves-wildlife-on-the-great-barrier-reef-with-few-options-179570">unrecognisable as a functioning ecosystem</a>.</p>
<p>But the scale of climate threat is beyond the tools currently used to manage the Great Barrier Reef. New measures and sustained effort are needed – at local, national, and international scales – if we’re serious about saving this natural wonder.</p>
<h2>International treasure under threat</h2>
<p>The Great Barrier Reef is internationally renowned for its <a href="https://elibrary.gbrmpa.gov.au/jspui/handle/11017/2787">biodiversity</a>, including more than 450 species of coral, 1,600 species of fish and 6,000 species of molluscs. </p>
<p>It is also an <a href="https://www2.gbrmpa.gov.au/learn/reef-facts">economic workhorse</a>, contributing about A$6 billion to the Australian economy and providing some 64,000 full-time jobs. Many industries and coastal communities in Queensland rely on a healthy Great Barrier Reef. </p>
<p>But Australia’s reefs are <a href="https://theconversation.com/the-great-barrier-reef-is-in-trouble-there-are-a-whopping-45-reasons-why-122930">in trouble</a> and climate change is the biggest threat – bringing heatwaves, severe cyclones and more acidic oceans.</p>
<p>The background temperature of the Great Barrier Reef has <a href="https://www2.gbrmpa.gov.au/learn/threats/sea-temperature">warmed by 0.8°C</a> since 1910. This warming can couple with ocean temperature variability, such as from El Niño and its counterpart, La Niña. But because the Great Barrier Reef is already struggling under climate change, an El Niño could mean even more pressure.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-the-next-australian-government-must-do-to-save-the-great-barrier-reef-182861">What the next Australian government must do to save the Great Barrier Reef</a>
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<figure class="align-center ">
<img alt="Graph showing changes in sea temperature, ocean pH, sea level and tropical cyclones" src="https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=327&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=327&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=327&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=410&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=410&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530022/original/file-20230605-29-jm1why.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=410&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Indicative changes in sea temperature, ocean pH, sea level and tropical cyclones based on climate projections (from Great Barrier Reef 2019 Outlook Report).</span>
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</figure>
<h2>The bathtub is filling</h2>
<p>We hope this analogy helps explain the situation.</p>
<p>Imagine a bathtub. The water inside it represents global sea-surface temperature. When the bathtub was only half-full, temporary heat variability (from El Niño) caused splashes, but they were contained in the tub.</p>
<p>Now fast-forward to the present day. For more than a century, humans have been heating the planet by burning fossil fuels. The background temperature has risen and the bathtub is now almost filled to the brim. Add a splash of heat from El Niño and the bath spills over.</p>
<p>These splashes bring consequences: more mass bleaching of coral and, in severe cases, widespread coral death.</p>
<p>El Niño and La Niña have become <a href="https://theconversation.com/new-study-helps-solve-a-30-year-old-puzzle-how-is-climate-change-affecting-el-nino-and-la-nina-205128">more variable</a> in recent decades. This has meant more frequent and stronger events – bigger splashes in the bathtub – that pose a grave threat to the Great Barrier Reef’s health and biodiversity. </p>
<p>All the while, the bathtub keeps filling. </p>
<p>The World Meteorological Organisation <a href="https://hadleyserver.metoffice.gov.uk/wmolc/WMO_GADCU_2023-2027.pdf">reported</a> that the next five years will be the warmest since records began. And 2023 will almost certainly be among the <a href="https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202304/supplemental/page-2">ten warmest years</a> on record. </p>
<p>Earth’s average temperature is <a href="https://theconversation.com/global-warming-to-bring-record-hot-year-by-2028-probably-our-first-above-1-5-c-limit-205758">predicted</a> to exceed 1.5°C of warming in at least one of the next five years. This would produce a big splash – but it doesn’t represent the bathtub level reaching the brim.</p>
<p>Under the global climate accord known as the Paris Agreement, nations <a href="https://unfccc.int/process-and-meetings/the-paris-agreement">are pursuing efforts to limit</a> the average global temperature increase to 1.5°C above pre-industrial levels. Background warming beyond 1.5°C is widely considered by climate scientists as dangerous. We’re entering an era in which hot and more frequent splashes are imminent – and the survival of coral reefs is becoming increasingly threatened.</p>
<p>Clearly, the global warming we’re seeing now is unprecedented. We must turn off the tap.</p>
<figure class="align-center ">
<img alt="graph showing increase in atmospheric CO₂ concentration" src="https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=349&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=349&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=349&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=438&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=438&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530226/original/file-20230606-23-9qrejq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=438&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Atmospheric carbon dioxide concentration from the Mauna Loa Observatory has increased from below 320 parts per million (ppm) to over 420 ppm since 1958 (Data: Scripps CO₂ Program).</span>
</figcaption>
</figure>
<h2>An inadequate tool kit</h2>
<p>Unless global emissions are drastically reduced, frequent severe bleaching is <a href="https://unesdoc.unesco.org/ark:/48223/pf0000265625">projected</a> this century for all 29 World Heritage-listed coral reefs.</p>
<p>This would cause untold ecological damage. It would also reduce the reefs’ ability to support human communities that depend on them.</p>
<p>Coral bleaching is not the only threat to the Great Barrier Reef. <a href="https://theconversation.com/we-all-know-the-great-barrier-reef-is-in-danger-the-un-has-just-confirmed-it-again-195551#:%7E:text=The%20most%20significant%20threats%20are,unsustainable%20fishing%20and%20coastal%20development.">Other</a> pressing problems include poor water quality from land-based runoff, crown-of-thorns starfish and unsustainable fishing and coastal development.</p>
<p>So how do we deal with all of this? A range of management actions exists. </p>
<p>Banning fishing in some areas and limiting exploitation elsewhere has benefited conservation, while also <a href="https://www.sciencedirect.com/science/article/pii/S0960982212003958">enhancing fisheries</a>.</p>
<p>But other actions have had mixed success. And not all available tools are being applied effectively.</p>
<p>For example, “<a href="https://www2.gbrmpa.gov.au/access/zoning/special-management-areas">special management areas</a>” were intended to restrict human use of the Great Barrier Reef for conservation or management purposes. But their use has been limited. And emergency implementations of these areas, allowed under the law, have never been used.</p>
<p>Crucially, none of the available actions were designed to respond to climate threats. The reality is, the scale of climate disturbance is beyond the available management tools.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-all-know-the-great-barrier-reef-is-in-danger-the-un-has-just-confirmed-it-again-195551">We all know the Great Barrier Reef is in danger – the UN has just confirmed it. Again</a>
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</em>
</p>
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<figure>
<iframe src="https://player.vimeo.com/video/404223289" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Source: Australian Academy of Science.</span></figcaption>
</figure>
<h2>What are we waiting for?</h2>
<p>The scientific evidence is unequivocal. We must work at local, national, and international scales to help the Great Barrier Reef better cope with climate change. The likely arrival of an El Niño makes this task ever more urgent. </p>
<p>Australian and international governments must take immediate and decisive action on emissions reduction. This includes banning new coal and gas projects and rapidly shifting to renewable energy. Communities reliant on fossil-fuel industries should be helped to transition to new livelihoods.</p>
<p>Reef management agencies need to tackle climate threats more effectively – at a scale commensurate with the problem. This requires a new way of managing key areas. That could mean, for example, temporarily closing off parts of the Great Barrier Reef affected by coral bleaching to give them a reprieve from other stressors such as fishing and tourism.</p>
<p>And individuals must also ensure our everyday choices – in transport, consumption and elsewhere – help tackle the climate threat.</p>
<p>It’s time for us all to double-down and ensure the survival of the Great Barrier Reef, and the planet. There is no room for complacency. So what are we waiting for?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/adapt-move-or-die-repeated-coral-bleaching-leaves-wildlife-on-the-great-barrier-reef-with-few-options-179570">Adapt, move, or die: repeated coral bleaching leaves wildlife on the Great Barrier Reef with few options</a>
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</p>
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<img src="https://counter.theconversation.com/content/206750/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Scott F. Heron is receiving and has received funding from Australian Research Council, as well as from international government sources. Together with Jon Day, Scott developed the Climate Vulnerability Index (CVI) for World Heritage that has also been applied to assess climate impacts upon other areas of significance.</span></em></p><p class="fine-print"><em><span>Jodie L. Rummer has received funding from the Australian Research Council. She is the current Vice President of the Australian Coral Reef Society.</span></em></p><p class="fine-print"><em><span>Jon Day previously worked for the Great Barrier Reef Marine Park Authority between 1986 and 2014, and was one of the Directors at GBRMPA between 1998 and 2014. He represented Australia as one of the formal delegates to the World Heritage Committee between 2007-2011.</span></em></p>The scale of climate threat is beyond the tools we have to manage the Great Barrier Reef. New measures and sustained effort are needed.Scott F. Heron, Associate Professor in Physics, James Cook UniversityJodie L. Rummer, Professor of Marine Biology, James Cook UniversityJon C. Day, PSM, Adjunct Senior Research Fellow, College of Science and Engineering, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1955512022-11-29T07:14:29Z2022-11-29T07:14:29ZWe all know the Great Barrier Reef is in danger – the UN has just confirmed it. Again<figure><img src="https://images.theconversation.com/files/497824/original/file-20221129-18-4gf988.jpg?ixlib=rb-1.1.0&rect=0%2C232%2C3519%2C2548&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Kristin Hoel/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>You might be forgiven for thinking it’s Groundhog Day <a href="https://www.abc.net.au/news/2022-11-29/united-nations-queensland-great-barrier-reef-danger-report/101705908">reading headlines</a> about the Great Barrier Reef potentially being listed on the World Heritage “in danger” list. After all, there have been similar calls in 2012, 2013, 2014 and 2017.</p>
<p>Successive federal governments have lobbied hard to keep the largest coral reef in the world off the <a href="https://whc.unesco.org/en/danger/">high-profile list</a> kept by the United Nations Educational, Scientific and Cultural Organization (UNESCO). </p>
<p>Only last year, former environment minister Sussan Ley jetted around the world in a successful effort to <a href="https://theconversation.com/not-declaring-the-great-barrier-reef-as-in-danger-only-postpones-the-inevitable-164867">stave off the inevitable</a>, pointing to hundreds of millions of dollars spent on issues such as water quality. The new minister, Tanya Plibersek, also <a href="https://abcnews.go.com/International/wireStory/australia-argues-endangered-barrier-reef-status-94118273">wants to avoid</a> having the reef “singled out” in this way. </p>
<p>The question is, what does in-danger mean? Everyone knows the reef is in trouble. An in-danger listing is not a sanction or punishment. Rather, it’s a call to the international community that a World Heritage property is under threat, requiring actions to protect it for future generations. In-danger listing is not permanent, nor does it mean the Reef will be permanently removed from the World Heritage list.</p>
<p>The reef faces a <a href="https://theconversation.com/the-great-barrier-reef-is-in-trouble-there-are-a-whopping-45-reasons-why-122930">multitude of threats</a>. The most significant threats are coral bleaching worsened by climate change, poor water quality from land-based runoff, and unsustainable fishing and coastal development. We already have regulations to tackle many of them – but we need more effective enforcement to ensure compliance. </p>
<h2>What just happened?</h2>
<p>The Great Barrier Reef has been <a href="https://whc.unesco.org/en/list/154/">World Heritage listed</a> since 1981. This means it’s considered an area of outstanding value to humanity. Covering an area the size of Italy, this iconic area includes some 3,000 separate reefs, over 1,000 islands and a variety of other significant habitats. </p>
<p>The latest UN mission has just <a href="https://whc.unesco.org/document/197090">reported back</a>, finding the reef’s condition is worsening and recommending it be listed as “in danger”. It also offered practical solutions.</p>
<p>Previous governments have fought to ensure the reef is not listed as in-danger despite their own five-yearly reviews demonstrating an obvious decline. In 2009, the reef’s condition was <a href="https://elibrary.gbrmpa.gov.au/jspui/handle/11017/199">rated poor</a> and declining. In 2014 it was <a href="https://elibrary.gbrmpa.gov.au/jspui/handle/11017/2855">poor</a> and declining and in 2019, <a href="https://www2.gbrmpa.gov.au/our-work/outlook-report-2019">very poor</a> and declining. </p>
<p>So the government knows the reef is in danger. We know, and the tourism industry knows. While some tourism operators worry about their business, the opposite appears to be true: <a href="https://theconversation.com/does-tourism-really-suffer-at-sites-listed-as-world-heritage-in-danger-60697">more people go</a>, thinking it might be their last chance to see it. And already, operators are adapting by taking tourists to areas still in good condition.</p>
<p>Federal governments just don’t want the reef on the list because of the hit to their international reputation – and to their domestic standing. </p>
<p>If the reef is officially listed as “in danger” next year, it will draw a much greater focus to the reef’s plight. And that may help galvanise effective national and global action. </p>
<p>Take the case of the famous coral reefs of Belize in Central America. When these reefs were listed, the government banned nearby oil exploration and protected mangroves. Belize’s reefs have now been <a href="https://whc.unesco.org/en/news/1838">taken off</a> the in-danger list. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/does-tourism-really-suffer-at-sites-listed-as-world-heritage-in-danger-60697">Does tourism really suffer at sites listed as World Heritage In Danger?</a>
</strong>
</em>
</p>
<hr>
<h2>So what has to be done?</h2>
<p>The mission’s report lays out what needs to be done for the major issues.</p>
<p>Australia already has a <a href="https://www.dcceew.gov.au/parks-heritage/great-barrier-reef/long-term-sustainability-plan">long-term plan</a> aimed at ensuring the reef’s sustainability. There are regulations governing, say, sediment and water quality in run off from agriculture and towns. We have some targets too, particularly around water quality. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="flood plume reef" src="https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497880/original/file-20221129-16-kzqmd9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&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 2019 photo shows two threats to the Great Barrier Reef: coal ships anchored near Abbot Point and a flood plume from the Burdekin River. These plumes can carry pollutants and debris to the reef.</span>
<span class="attribution"><span class="source">Matt Curnock</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The problem is delivery. There is a need to scale up efforts and improve compliance. Regulations mean very little if there’s ineffective enforcement. For example, while most farmers have taken on board the rules around fertiliser use, erosion and run-off, those flouting the rules get only a slap on the wrist. As the state government <a href="https://www.qld.gov.au/__data/assets/pdf_file/0017/110591/reef-protection-regulations-factsheet.pdf">notes</a>, enforcement is a “last resort”. </p>
<p>The UN mission has called on Australia to improve in four key areas: </p>
<p><strong>1. Look after land and water</strong></p>
<p>When native vegetation is cleared, it makes erosion more likely. Eroded soils are washed downstream and out to sea, where they can settle on coral and seagrass, smothering them. In Queensland, native vegetation is still being cleared at unsustainable levels. </p>
<p><strong>2. Phase out gillnets</strong></p>
<p>These long nets catch fish by their gills. But they also catch dugongs, dolphins and turtles, which then die. The UN mission made a very strong recommendation: phase out gillnets in the marine park. </p>
<p><strong>3. More effective disposal of dredge spoil</strong></p>
<p>Dredging shipping channels and ports produces a lot of silt and sand. If this is dumped in shallow areas, it can also spread to nearby corals and seagrass beds already under stress from climate change. A previous government policy ended the dumping of capital dredge spoil (dredging previously undisturbed areas). But maintenance dredge spoil is still being dumped at sea or used for reclamation, both causing adverse impacts. </p>
<p><strong>4. Tackle climate change</strong></p>
<p>This month, the northern reefs are sweltering in <a href="https://www.theguardian.com/environment/2022/nov/25/record-heat-over-great-barrier-reef-raises-fears-of-second-summer-of-coral-bleaching">record water temperatures</a> – raising the chance of further bleaching events. The UN report makes it clear that climate change is the biggest threat. Climate change heats up tropical waters, causing coral bleaching and potentially coral death. Australia, as one of the world’s top exporters of fossil fuels gas and coal, has long tried to go slow on climate action. The new government has moved to legislate a stronger 2030 emissions reduction target, but the UN report calls for even more ambition to keep warming under 1.5°C as this is widely accepted as the critical threshold for <a href="https://unesdoc.unesco.org/ark:/48223/pf0000265625">reef survival</a>. </p>
<p>The report doesn’t make reference to the impacts of shipping on nearby coral and seagrass areas, such as sediment churned up by propellers of large ships and tankers. </p>
<h2>Death by a thousand cuts</h2>
<p>If you dive the reef for the first time this year, you might wonder if there really is a problem. After all, there are still fish and coral. When I first dove on the reef more than 35 years ago, it was in much better condition. What you see now <a href="https://theconversation.com/why-grandparents-should-talk-to-children-about-the-natural-world-of-their-youth-144807">may seem okay</a> – but it’s a pale shadow of what it could or should be. It’s death by a thousand cuts. </p>
<p>As reef expert Professor Ove Hoegh-Guldberg <a href="https://www.thesaturdaypaper.com.au/news/politics/2016/06/04/the-real-story-the-great-barrier-reef/14649624003332">has said</a>: </p>
<blockquote>
<p>The reef is in dire trouble, but it’s decades away before it’s no longer worth visiting. That’s the truth. But unless we wake up and deal with climate change sincerely and deeply then we really will have a Great Barrier Reef not worth visiting.</p>
</blockquote>
<p>We’re never going to restore the reef to its pre-European conditions. But unless we take real action, future generations will wonder how and why we failed them so badly. We don’t need to wait for the World Heritage Committee to make in-danger listing to know the reef is in real trouble. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/severely-threatened-and-deteriorating-global-authority-on-nature-lists-the-great-barrier-reef-as-critical-151275">'Severely threatened and deteriorating': global authority on nature lists the Great Barrier Reef as critical</a>
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</p>
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<img src="https://counter.theconversation.com/content/195551/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jon Day previously worked for the Great Barrier Reef Marine Park Authority between 1986 and 2014, and was one of the Directors at GBRMPA between 1998 and 2014. He represented Australia as one of the formal delegates to the World Heritage Committee between 2007-2011.</span></em></p>Environment ministers from both sides are determined not to see the Barrier Reef listed as in danger. The question is – why?Jon C. Day, PSM, Adjunct Senior Research Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1828612022-05-12T20:01:34Z2022-05-12T20:01:34ZWhat the next Australian government must do to save the Great Barrier Reef<figure><img src="https://images.theconversation.com/files/462631/original/file-20220512-16-qljf6d.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4210%2C2791&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Getty Images</span></span></figcaption></figure><p>Widespread coral bleaching has <a href="https://www.theguardian.com/environment/2022/may/10/devastating-90-of-reefs-surveyed-on-great-barrier-reef-affected-by-coral-bleaching-in-2022">now occurred</a> on the Great Barrier Reef for the fourth time in seven years. As the world has heated up more and more, there’s less and less chance for corals to recover.</p>
<p>This year, the Morrison government announced a <a href="https://theconversation.com/the-1-billion-great-barrier-reef-funding-is-nonsensical-australians-and-their-natural-wonder-deserve-so-much-better-175924">A$1 billion plan</a> to help the reef. This plan tackles some of the problems the reef faces – like poor water quality from floods as well as agricultural and industrial runoff. But it makes no mention of the elephant in the room. The world’s largest living assemblage of organisms is facing collapse because of one major threat: climate change.</p>
<p>Our window of opportunity to act is narrowing. We and other scientists have warned about this for decades. Australia has doubled down on coal and gas exports with <a href="https://australiainstitute.org.au/post/australian-fossil-fuel-subsidies-surge-to-11-6-billion-in-2021-22/">subsidies of $20 billion</a> in the past two years. When these fossil fuels are burned, they produce carbon dioxide and other greenhouse gases that trap more heat in the atmosphere that also warms the ocean.</p>
<p>If our next federal government wants to save the reef, it must tackle the main reason it is in trouble by phasing out fossil fuel use and exports as quickly as possible. Otherwise it’s like putting bandaids on an arterial wound. But to help the reef get through the next decades of warming we’ve already locked in, we will still need that $1 billion to help reduce other stressors.</p>
<h2>Why is this new bleaching event such bad news?</h2>
<p>Past bleaching events have been linked to El Niño events. Stable atmospheric conditions can bring calm, cloud-free periods that heat up the water around the reef. That can bring extreme summer temperatures – and that is when corals bleach.</p>
<p>This year is a La Niña, which can bring warmer-than-usual temperatures but also tends to bring more clouds, rain, and storms that mix up the waters. These usually spread the heat to the deeper parts of the ocean and mean lower temperature for corals. Not this time. </p>
<p>Global warming means corals are already close to their bleaching threshold, and it doesn’t take much heat to tip the balance. Water temperatures across the reef have been several degrees hotter than the long-term average. And the corals are feeling the heat.</p>
<p>Four times in seven years means that bleaching events are accelerating. Predictions have suggested that bleaching will become an annual event in a little over two decades. It may not be that long. </p>
<p>You always remember the first time you see bleaching in real life. For co-author Jodie, that was in 2016, off Lizard Island, a previously pristine part of the reef far from human impacts or water quality issues. The water was shockingly warm. Looking at our dive computers, we saw that the temperatures we had been simulating in our laboratories for 2050 were already here. </p>
<p>For a week, the marine heatwave pushed the corals to their limits. When corals experience heat stress, some initially turn fluorescent while others go stark white. Then the water goes murky – that’s death in the water. It’s heartbreaking to see. Grief is common among marine scientists right now. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-1-billion-great-barrier-reef-funding-is-nonsensical-australians-and-their-natural-wonder-deserve-so-much-better-175924">The $1 billion Great Barrier Reef funding is nonsensical. Australians, and their natural wonder, deserve so much better</a>
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</em>
</p>
<hr>
<p>Corals can recover from bleaching if they get a recovery period. But annual bleaching means there is not enough time for proper recovery. Even the most robust corals can’t survive this year after year. </p>
<p>Some people hope the reef can adapt to hotter conditions – but there is little evidence it can happen fast enough to outpace warming. While some fish can move to cooler waters further south, corals face ocean acidification, yet another problem caused by carbon dioxide emissions. As CO₂ is absorbed by the ocean, the changed chemistry makes it harder for corals to build their skeleton (and for other marine organisms to form a shell). There’s no safe place for corals to go. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close up of coral" src="https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=534&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=534&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462633/original/file-20220512-24-gb6u6j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=534&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">More acidic seawater makes it harder for coral polyps to build their skeletons.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What does the next government need to do?</h2>
<p>The evidence is clear. We see it with our own eyes. We’re barrelling towards catastrophic levels of warming, and there’s not enough action. </p>
<p>As it stands, policies on offer by our two major parties will not save the reef, according to <a href="https://climateanalytics.org/publications/2022/australian-election-2022-political-party-and-independent-climate-goals-analysis/">new research</a> by Climate Analytics. Current Coalition emissions reduction targets of 26-28% by 2030 would lead to a 3°C warmer world, which would be devastating for the Great Barrier Reef. </p>
<p>Labor’s policies of a 43% reduction by 2030 still lead to 2°C of warming. The teal independents and the Greens have policies compatible with keeping warming to 1.5°C, though how to achieve those goals is unclear. What is clear is that every tenth of a degree matters.</p>
<p>We need leaders who are serious about climate action. Who can acknowledge the truth that the problem is real, that we’re causing it, and that it’s hurting us right now. </p>
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Read more:
<a href="https://theconversation.com/australias-next-government-must-tackle-our-collapsing-ecosystems-and-extinction-crisis-182048">Australia's next government must tackle our collapsing ecosystems and extinction crisis</a>
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<p>There are still a few people sceptical that humans can change the climate. But today the changes are apparent. </p>
<p>The words “unprecedented” and “record-breaking” are starting to lose relevance for natural disasters because they are used more and more. Australians faced the 2019/20 Black Summer of megafires. This year we’ve had major flooding. Marine heatwaves have killed off almost all of Tasmania’s giant kelp. </p>
<p>But climate impacts are also being seen around the world – extraordinary drought gripping California, fires in melting Siberia and events <a href="https://www.nytimes.com/2021/07/09/climate/marine-heat-wave.html">scientists consider</a> to be “virtually impossible without the influence of human-caused climate change”. That includes the accelerating impacts on coral reefs worldwide.</p>
<p>We need government policies matching the scale and urgency of the threat. That means getting to net zero as soon as possible. It isn’t only about the reef – it’s about all land and sea natural systems vulnerable to climate change, and the people who rely on them. </p>
<p>No developed country has more to lose from inaction on climate than Australia. But no country has more to gain by shifting to clean energy, through new economic opportunities, new jobs, and better protection for our natural treasures.</p><img src="https://counter.theconversation.com/content/182861/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jodie L. Rummer has received funding from the Australian Research Council (ARC) and the ARC Centre of Excellence for Coral Reef Studies. She is also affiliated with the Australian Coral Reef Society. </span></em></p><p class="fine-print"><em><span>Scott F. Heron has received funding from Australian Research Council and NASA ROSES Ecological Forecasting.</span></em></p>Efforts to save the reef aren’t tackling the main cause: climate change. What we need from our next federal government is strong leadership to avert the climate crisis.Jodie L. Rummer, Associate Professor & Principal Research Fellow, James Cook UniversityScott F. Heron, Associate Professor in Physics, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1823112022-05-05T18:01:15Z2022-05-05T18:01:15ZCorals and sea anemones turn sunscreen into toxins – understanding how could help save coral reefs<figure><img src="https://images.theconversation.com/files/461387/original/file-20220504-16-dvzlw6.jpg?ixlib=rb-1.1.0&rect=172%2C181%2C4820%2C3423&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Many places have banned sunscreens with certain chemicals in an attempt to help protect coral reefs.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/egypt-red-sea-hurghada-teenage-girl-snorkeling-at-royalty-free-image/932631960?adppopup=true">Westend61 via Getty Images</a></span></figcaption></figure><p>Sunscreen bottles are frequently labeled as “reef-friendly” and “coral-safe.” These claims generally mean that the lotions replaced oxybenzone – a chemical that can harm corals – with something else. But are these other chemicals really safer for reefs than oxybenzone?</p>
<p>This question led <a href="https://mitchlab.sites.stanford.edu/djordje-vuckovic">us</a>, two <a href="https://scholar.google.com/citations?hl=en&user=RQcNZ6QAAAAJ">environmental chemists</a>, to team up with <a href="https://med.stanford.edu/pringlelab/people/john-pringle.html">biologists</a> who study <a href="https://med.stanford.edu/pringlelab.html">sea anemones as a model for corals</a>. Our goal was to uncover how sunscreen harms reefs so that we could better understand which components in sunscreens are really “coral-safe.” </p>
<p>In <a href="https://www.science.org/doi/10.1126/science.abo4627">our new study</a>, published in Science, we found that when corals and sea anemones absorb oxybenzone, <a href="https://doi.org/10.1126/science.abn2600">their cells turn it into phototoxins</a>, molecules that are harmless in the dark but become toxic under sunlight.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dead coral reef." src="https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461392/original/file-20220504-19-dpmjpk.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">Reefs around the world – like the Great Barrier Reef seen here – are bleaching and dying because of stressors like increased water temperatures, and sunscreens may be exacerbating the issues.</span>
<span class="attribution"><span class="source">Amanda Tinoco</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Protecting people, harming reefs</h2>
<p>Sunlight is made of many different wavelengths of light. Longer wavelengths – like visible light – are typically harmless. But light at shorter wavelengths – like ultraviolet light – can pass through the surface of skin and damage DNA and cells. Sunscreens, including oxybenzone, work by absorbing most of the UV light and converting it into heat.</p>
<p>Coral reefs around the world have suffered in recent decades from <a href="https://oceanservice.noaa.gov/facts/coralreef-climate.html">warming oceans and other stressors</a>. Some scientists thought that sunscreens coming off of swimmers or from wastewater discharges could also be harming corals. They conducted lab experiments that showed that oxybenzone concentrations as low as 0.14 mg per liter of seawater can <a href="https://doi.org/10.1007/s00244-015-0227-7">kill 50% of coral larvae in less than 24 hours</a>. While most field samples typically have lower sunscreen concentrations, one popular snorkeling reef in the U.S. Virgin Islands <a href="https://doi.org/10.1007/s00244-015-0227-7">had up to 1.4 mg oxybenzone per liter of seawater</a> – more than 10 times the lethal dose for coral larvae. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chemical diagram of oxybenzone." src="https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=403&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=403&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461389/original/file-20220504-21-dognyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=403&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Oxybenzone is a common ingredient in many sunscreens.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Oxybenzone.svg#/media/File:Oxybenzone.svg">Fvasconcellos via WikimediaCommons</a></span>
</figcaption>
</figure>
<p>Likely inspired by this research and a number of <a href="https://dx.doi.org/10.1289%2Fehp.10966">other studies</a> <a href="https://doi.org/10.1080/10934529.2011.602936">showing damage</a> to <a href="https://doi.org/10.1016/j.aquatox.2008.08.018">marine life</a>, Hawaii’s legislators <a href="https://www.washingtonpost.com/news/energy-environment/wp/2018/05/02/hawaii-might-be-about-to-ban-your-favorite-sunscreen-to-protect-its-coral-reefs/">voted</a> in 2018 to ban oxybenzone and another ingredient in sunscreens. Soon after, lawmakers in other places with coral reefs, like the <a href="https://psmag.com/news/the-us-virgin-islands-bans-potentially-dangerous-sunscreen-chemicals">Virgin Islands</a>, <a href="https://www.nytimes.com/2018/11/02/world/asia/palau-sunscreen-ban-coral.html">Palau</a> and <a href="https://www.visitaruba.com/news/general/aruba-officially-bans-plastics-and-oxybenzone/">Aruba</a>, implemented their own bans.</p>
<p>There is still an <a href="https://theconversation.com/theres-insufficient-evidence-your-sunscreen-harms-coral-reefs-109567">open debate</a> whether the concentrations of oxybenzone in the environment are high enough to damage reefs. But everyone agrees that these chemicals can cause harm under certain conditions, so understanding their mechanism is important. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A number of small test tubes with little sea anemones growing inside of them." src="https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461396/original/file-20220504-15-7bssds.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">By putting sea anemones into test tubes with oxybenzone and controlling what kinds of light they were exposed to, we could see whether the sunscreen was reacting to light.</span>
<span class="attribution"><span class="source">Djordje Vuckovic</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Sunscreen or toxin</h2>
<p>While laboratory evidence had shown that sunscreen can harm corals, very little research had been done to understand how. Some studies suggested that oxybenzone <a href="https://doi.org/10.1016/j.envint.2014.05.015">mimics hormones</a>, disrupting reproduction and development. But another theory that our team found particularly intriguing was the possibility that the sunscreen behaved as a <a href="https://doi.org/10.1007/s00244-015-0227-7">light-activated toxin in corals</a>. </p>
<p>To test this, we used the sea anemones our colleagues breed as a model for corals. Sea anemones and corals are closely related and share a lot of biological processes, including a symbiotic relationship with algae that live within them. It is <a href="https://doi.org/10.1016/j.tree.2008.03.004">extremely difficult to perform experiments with corals under lab conditions</a>, so anemones are typically much better for lab-based studies like ours.</p>
<p>We put 21 anemones in test tubes full of seawater under a lightbulb that emits the full spectrum of sunlight. We covered five of the anemones with a box made of acrylic that blocks the exact wavelengths of UV light that oxybenzone normally absorbs and interacts with. Then we exposed all the anemones to 2 mg of oxybenzone per liter of seawater.</p>
<p>The anemones under the acrylic box were our “dark” samples and the ones outside of it our control “light” samples. Anemones, like corals, have a translucent surface, so if oxybenzone were acting as a phototoxin, the UV rays hitting the light group would trigger a chemical reaction and kill the animals – while the dark group would survive.</p>
<p>We ran the experiment for 21 days. On Day Six, the first anemone in the light group died. By Day 17, <a href="https://doi.org/10.1126/science.abn2600">all of them had died</a>. By comparison, none of the five anemones in the dark group died during the entire three weeks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up of a blue coral." src="https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461391/original/file-20220504-18-8tlovg.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">Corals – like the mushroom coral seen here – and sea anemones absorb oxybenzone and metabolize it, but in doing so, they turn it into a toxin.</span>
<span class="attribution"><span class="source">Christian Renicke</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Metabolism converts oxybenzone to phototoxins</h2>
<p>We were surprised that a sunscreen was behaving as a phototoxin inside the anemones. We ran a chemical experiment on oxybenzone and confirmed that, on its own, it behaves as a sunscreen and not as a phototoxin. It’s only when the chemical was absorbed by anemones that it became dangerous under light. </p>
<p>Any time an organism absorbs a foreign substance, its cells try to get rid of the substance using various metabolic processes. Our experiments suggested that one of these processes was turning oxybenzone into a phototoxin.</p>
<p>To test this, we analyzed the chemicals that formed inside anemones after we exposed them to oxybenzone. We learned that our anemones had replaced part of oxybenzone’s chemical structure – a specific hydrogen atom on an alcohol group – with a sugar. Replacing hydrogen atoms on alcohol groups with sugars is something that <a href="https://passel2.unl.edu/view/lesson/2aee31ac6c74/7#:%7E:text=Phase%20II%20-%20Introduction,-Phase%20II%20reactions&text=reactions%20are%20anabolic%20processes%20which,solubility%20and%20usually%20reduced%20mobility.">plants</a> and <a href="https://doi.org/10.1007/1-4020-4142-X_3">animals</a> commonly do to make chemicals less toxic and more water soluble so they are easier to excrete.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chemical chart showing two different molecular structures." src="https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=155&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=155&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=155&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=195&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=195&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461602/original/file-20220505-21-skvp4z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=195&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When cells try to process oxybenzone, they replace part of an alcohol group (highlighted in red on the left) with a sugar (in red on the right) and in doing so turn the sunscreen into a phototoxin.</span>
<span class="attribution"><span class="source">Djordje Vuckovic</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>But when you remove this alcohol group from oxybenzone, oxybenzone ceases to function as a sunscreen. Instead, it holds on to the energy it absorbs from UV light and kicks off a series of <a href="https://doi.org/10.1111/php.12716">rapid chemical reactions</a> that <a href="https://doi.org/10.1021/acsomega.9b03244">damage cells</a>. Rather than turning the sunscreen into a harmless, easy-to-excrete molecule, the anemones <a href="https://doi.org/10.1126/science.abn2600">convert oxybenzone into a potent, sunlight-activated toxin</a>.</p>
<p>When we ran similar experiments with mushroom corals, we found something surprising. Even though <a href="https://doi.org/10.1016/j.tree.2008.03.004">corals are much more vulnerable to stressors than sea anemones</a>, they did not die from oxybenzone and light exposure during our entire eight-day experiment. The coral made the same phototoxins from oxybenzone, but all of the toxins were stored in the symbiotic algae living in the coral. The algae seemed to absorb the phototoxic byproducts and, in doing so, likely protected their coral hosts. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two rows of photos of sea anemones, with the top row showing a slower death." src="https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=128&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=128&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=128&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=161&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=161&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461603/original/file-20220505-22-e336i2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=161&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 photo series shows how darker-colored anemones on top with algae in them lived longer than the lighter-colored anemones on the bottom that did not have algae living in them.</span>
<span class="attribution"><span class="source">Djordje Vuckovic and Christian Renicke</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We suspect that the corals would have died from the phototoxins if they did not have their algae. It is not possible to keep corals without algae alive in the lab, so we did some experiments on anemones without algae instead. These anemones died about two times faster and had almost three times as many phototoxins in their cells compared than the same anemones with algae.</p>
<h2>Coral bleaching, ‘reef-safe’ sunscreens and human safety</h2>
<p>We believe there are a few important takeaways from our effort to better understand how oxybenzone harms corals. </p>
<p>First, <a href="https://doi.org/10.1126/science.aan8048">coral bleaching events</a> – in which the corals expel their algal symbionts because of high seawater temperatures or other stressors – likely leave corals particularly vulnerable to the toxic effects of sunscreens. </p>
<p>Second, it’s possible that oxybenzone could also be dangerous to other species. In our study, we found that human cells can also turn oxybenzone into a potential phototoxin. If this happens inside the body, where no light can reach, it’s not an issue. But if this occurs in the skin, where light can create toxins, it could be a problem. Previous studies have suggested that oxybenzone <a href="https://doi.org/10.1097/PSN.0000000000000244">could pose health risks to people</a>, and some researchers have recently <a href="https://doi.org/10.1016/j.jaad.2021.12.011">called for more research into its safety</a>.</p>
<p>Finally, the chemicals used in many alternative “reef-safe” sunscreens contain the same alcohol group as oxybenzone – so could potentially also be converted to phototoxins.</p>
<p>We hope that, taken together, our results will lead to safer sunscreens and help inform efforts to protect reefs. </p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/182311/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Djordje Vuckovic has spoken with Soliome, a company involved in the production of novel sunscreen components. He received funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Bill Mitch has spoken with Soliome, a company involved in the production of novel sunscreen components. He receives funding from the U.S. National Science Foundation and the Stanford Woods Institute of the Environment.</span></em></p>Researchers have long suspected that an ingredient in sunscreen called oxybenzone was harming corals, but no one knew how. A new study shows how corals turn oxybenzone into a sunlight-activated toxin.Djordje Vuckovic, PhD candidate in Civil and Environmental Engineering, Stanford UniversityBill Mitch, Professor of Civil and Environmental Engineering, Stanford UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1801802022-03-29T03:49:22Z2022-03-29T03:49:22ZAnother mass bleaching event is devastating the Great Barrier Reef. What will it take for coral to survive?<figure><img src="https://images.theconversation.com/files/454879/original/file-20220329-4070-1pkrs9j.jpg?ixlib=rb-1.1.0&rect=0%2C31%2C5176%2C3414&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bleached coral beside the darker, healthier coral. Photo taken in February</span> <span class="attribution"><span class="source">Nathan Cook</span>, <span class="license">Author provided</span></span></figcaption></figure><p>It’s official: the Great Barrier Reef is suffering its <a href="https://www.bbc.com/news/world-australia-60870239">fourth mass bleaching event</a> since 2016. We dived into the reef yesterday and saw the unfolding crisis firsthand. </p>
<p>Descending beneath the surface at John Brewer Reef near Townsville, our eyes were immediately drawn to the iridescent whites, blues and pinks of stressed corals among the deeper browns, reds and greens of healthier colonies. </p>
<p>It’s a depressing, but all-too-familiar feeling. A sense of: “here we go again”</p>
<p>This is the first time the reef has bleached under the cooling conditions of the natural <a href="https://theconversation.com/back-so-soon-la-nina-heres-why-were-copping-two-soggy-summers-in-a-row-173684">La Niña weather pattern</a>, which shows just how strong the long-term warming trend of climate change is. Despite the cooling conditions, 2021 was one of <a href="https://theconversation.com/2021-was-one-of-the-hottest-years-on-record-and-it-could-also-be-the-coldest-well-ever-see-again-175238">the hottest years on record</a>.</p>
<p>When coral bleaches, it is not dead – yet. Coral reefs that suffer widespread bleaching can still recover if conditions improve, but it’s estimated to take <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2018.2908">up to 12 years</a>. That is, if there’s no new disturbance in the meantime, such as a cyclone or another bleaching event. </p>
<p>So what conditions are needed for coral recovery? And under what conditions will coral die?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diver inspects bleached coral" src="https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454882/original/file-20220329-4070-6lk17u.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">Bleaching at John Brewer Reef, near Townsville.</span>
<span class="attribution"><span class="source">Harriet Spark/Grumpy Turtle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>What it takes for coral to die</h2>
<p>Whether a coral can survive bleaching depends on how long conditions remain stressful, and to what level. What’s more, some <a href="https://doi.org/10.3389/fevo.2020.00178">species are more sensitive</a> than others, such as branching acropora corals, especially if they’ve bleached previously.</p>
<p>If water remains too warm for too long, corals will eventually die. But if the water temperature drops and the ultraviolet light becomes less intense, then the coral may recover and survive.</p>
<p>While the average sea temperatures in the reef currently remain above average, they’ve shown signs of cooling to a more amenable average for coral survival. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454880/original/file-20220329-25-1bs1wol.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bleaching at John Brewer Reef.</span>
<span class="attribution"><span class="source">Nathan Cook</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><a href="https://coralreefwatch.noaa.gov/">Sea temperatures</a> in Cleveland Bay, near Townsville, were above 31°C in early March, but thankfully have now reduced to below 29°C. <a href="https://coralreefwatch.noaa.gov/data_current/5km/v3.1_op/daily/png/coraltemp_v3.1_pacific_current.png">Similarly in</a> the Whitsundays, Hardy Reef experienced temperatures as high as 30°C but has receded to nearer 26°C in the past few weeks. </p>
<p>If coral does survives a bleaching event, it is still impacted physiologically, as bleaching can slow <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0088720">growth rates</a> and reduce <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(21)01346-4?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982221013464%3Fshowall%3Dtrue">reproductive capacity</a>. Surviving colonies also become more susceptible to other challenges, such as disease. </p>
<h2>Signs of stress</h2>
<p>Survival also depends on each individual coral’s own resilience: its ability to cope with higher temperatures and increased ultraviolet stress. </p>
<p>For example, fast growing branching corals are the most susceptible to bleaching and are generally the first to die. Long-lived massive corals, such as porites, may be less susceptible to bleaching, show minimal effects of bleaching and recover quicker.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Orange fish swim over bleached coral" src="https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454883/original/file-20220329-13-6efs8z.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">White and fluorescent corals are currently a common sight on many reefs.</span>
<span class="attribution"><span class="source">Harriet Spark/Grumpy Turtle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Corals can use fluorescent pigments to shield themselves from excessive ultraviolet radiation – a bit like sunscreen that lets coral manage, filter and attempt to regulate the incoming light. </p>
<p>To the casual observer, fluorescent corals look bright purple, pink, blue and yellow. For reef scientists, fluorescence is an obvious signal that corals are stressed and struggling to regulate their internal balance. As we’ve seen, white and fluorescent corals are currently a common sight on many reefs. </p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/adapt-move-or-die-repeated-coral-bleaching-leaves-wildlife-on-the-great-barrier-reef-with-few-options-179570">Adapt, move, or die: repeated coral bleaching leaves wildlife on the Great Barrier Reef with few options</a>
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<p>Most coral species have fluorescent pigments in their tissue. Some are always visible to humans, especially branching corals with bright blue or pink hues on the their branch tips. </p>
<p>Others are never visible, and some are visible only during times of heat stress when coral colonies boost these fluorescent pigments to fight the increasing ultraviolet intensity in warmer seas. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454884/original/file-20220329-19-qhgkr3.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">Bleaching can slow coral growth rates and reduce reproduction.</span>
<span class="attribution"><span class="source">Harriet Spark/Grumpy Turtle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Coral can’t adapt fast enough</h2>
<p>Scientists measure heat stress on corals using a metric called “<a href="https://ereefs.aims.gov.au/ereefs-aims/gbr1/dhw_heatstress">degree heating weeks</a>”. </p>
<p>One degree heating week is when the temperature at a given location is more than 1°C over the historical maximum temperature. If the water is 2°C above the historical maximum for one week, this would be considered two degree heating weeks. </p>
<p>Generally speaking, at four degree heating weeks, scientists expect to see signs of stress and coral bleaching. It usually takes eight degree heating weeks for coral to die. </p>
<p>According to Bureau of Meteorology <a href="http://www.bom.gov.au/environment/activities/reeftemp/reeftemp.shtml">data</a>, many parts of the Great Barrier Reef, such as off Cairns and Port Douglas, currently remain in the window of between four and eight degree heating weeks. But some areas, near Townsville and the Whitsundays, are experiencing severe bleaching stress beyond eight degree heating weeks. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1506414812904845316"}"></div></p>
<p>While we hope many coral reefs will recover from this round of bleaching, the long term implications cannot be understated.</p>
<p>When corals bleach, they eject their zooxanthellae – single-celled algae that gives coral colour and energy. Some corals may regain their zooxanthellae after the bleaching event is over, but this usually takes between three and six months. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/no-sunscreen-chemicals-are-not-bleaching-the-great-barrier-reef-179938">No, sunscreen chemicals are not bleaching the Great Barrier Reef</a>
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<hr>
<p>To make matters worse, full reef recovery requires no new bleaching events or other disturbances in the years that follow. Given the reef has bleached six times since the late 1990s, alongside global climate trajectories, this would appear an <a href="https://www.nature.com/articles/s41586-019-1081-y">unlikely scenario</a>. </p>
<p>While some corals may learn to cope with these new conditions by potentially acquiring more heat-tolerant zooxanthellae, the reality is that change is happening too fast for coral to adapt via evolution. </p>
<p>The severe bleaching in previous years also means future events may appear less severe. But this is simply because most of the heat sensitive corals have <a href="https://doi.org/10.1016/j.cub.2021.09.078">already died</a>, potentially resulting in a lower probability of widespread severe bleaching.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diver inspects bleached coral" src="https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454885/original/file-20220329-20-d73q6x.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">Any policy without action on climate change is ineffective.</span>
<span class="attribution"><span class="source">Harriet Spark/Grumpy Turtle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>We need stronger climate policies and action</h2>
<p>Australia has the world’s best marine scientists and marine park managers. And yet, our policies are rated “<a href="https://climateactiontracker.org/countries/australia/">highly insufficient</a>”, according to the latest Climate Action Tracker. </p>
<p>If global emissions continue unabated, Australia may warm <a href="https://theconversation.com/climate-change-has-already-hit-australia-unless-we-act-now-a-hotter-drier-and-more-dangerous-future-awaits-ipcc-warns-165396">by 4°C or more</a> this century. Under this scenario, widespread coral bleaching is likely on the Great Barrier Reef every year <a href="https://www.climatecouncil.org.au/resources/dire-warning-great-barrier-reef-un-inspection-begins-climate-council-briefing/">from 2044 onward</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1507209794368970758"}"></div></p>
<p>There has been some glimmers of hope in federal policy in recent years, such as <a href="https://elibrary.gbrmpa.gov.au/jspui/handle/11017/3460">statements recognising</a> the existential threat climate change poses to coral reefs. Despite this recognition, substantial action is lacking, as any policy without action on climate change is ineffective. </p>
<p>If the federal government, reef businesses and individuals are to show leadership and maintain healthy reefs, we need to work together and take rapid, drastic action to reduce carbon emissions. </p>
<p>Committing to a stronger emissions target for 2030 and a carbon neutral footprint for all Great Barrier Reef businesses would go a long way to exhibiting the kind of change required if coral reefs, in their current form, are to survive into the future. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-has-already-hit-australia-unless-we-act-now-a-hotter-drier-and-more-dangerous-future-awaits-ipcc-warns-165396">Climate change has already hit Australia. Unless we act now, a hotter, drier and more dangerous future awaits, IPCC warns</a>
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<img src="https://counter.theconversation.com/content/180180/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Smith receives funding from Australian and Queensland Government and the Great Barrier Reef Foundation.</span></em></p><p class="fine-print"><em><span>Nathan Cook is co-chair of the Australian Coral Restoration Consortium, a regional group of the Coral Restoration Consortium. </span></em></p>Coral reefs that suffer widespread bleaching can still recover if conditions improve, but it’s estimated to take up to 12 years. And that’s if no more bleaching events occur.Adam Smith, Adjunct Associate Professor, James Cook UniversityNathan Cook, Marine Scientist, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1799382022-03-27T19:12:25Z2022-03-27T19:12:25ZNo, sunscreen chemicals are not bleaching the Great Barrier Reef<figure><img src="https://images.theconversation.com/files/454291/original/file-20220325-21-5eoulu.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C5200%2C3448&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Getty Images</span></span></figcaption></figure><p>For the sixth time in the last 25 years, the Great Barrier Reef <a href="https://www.gbrmpa.gov.au/the-reef/reef-health">is bleaching</a>. During bleaching events, people are quick to point the finger at different causes, including <a href="https://owlcation.com/stem/Coral-Bleaching-and-Oxybenzone-Choose-Your-Sunscreen-Carefully">sunscreen</a>.</p>
<p>Why sunscreen? Some active ingredients can wash off snorkelers and into the reef, contaminating the area. So could this be the cause of the Barrier Reef’s bleaching? </p>
<p>In a word, no. I reviewed the evidence for sunscreen as a risk to coral in my <a href="https://www.publish.csiro.au/CH/CH21236">new research</a>, and found that while chemicals in sunscreen pose a risk to corals under laboratory conditions, they are only found at very low levels in real world environments. </p>
<p>That means when coral bleaching does occur, it is more likely to be due to the marine heatwaves and increased water temperatures that have come with climate change, as well as land-based run-off. </p>
<h2>Why have we been concerned over the environmental impact of sunscreens?</h2>
<p>After we apply sunscreen, the active ingredients can leach from our skin into the water. When we shower after swimming, soaps and detergents can further strip the these sunscreen chemicals off and send them into our waste water systems. They pass through treatment facilities, which cannot effectively remove them, and end up in rivers and oceans. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="hands putting on sunscreen" src="https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454296/original/file-20220325-21-1agae0v.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">Sunscreen isn’t the cause of the coral bleaching.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>It’s no surprise, then, that sunscreen contamination has been detected in freshwater and seas across the globe, from <a href="https://pubmed.ncbi.nlm.nih.gov/15996716/">Switzerland</a> to <a href="https://link.springer.com/article/10.1007/s11356-015-5174-3">Brazil</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/27235899/">Hong Kong</a>. Contamination is highest in the summer months, consistent with when people are more likely to go swimming, and peaks in the hours after people have finished swimming. </p>
<p>Four years ago, the Pacific island nation of Palau made world headlines by announcing plans to <a href="https://www.theguardian.com/world/2018/nov/02/pacific-island-to-introduce-world-first-reef-toxic-sunscreen-ban">ban all sunscreens</a> that contain specific synthetic active ingredients due to concern over the risk they posed to corals. <a href="https://www.cntraveler.com/story/these-destinations-are-banning-certain-sunscreens">Similar bans</a> have been announced by Hawaii, as well a number of other popular tourist areas in the Americas and Caribbean. </p>
<p>These bans are based on independent scientific studies and <a href="https://coralreefpalau.org/wp-content/uploads/2017/10/CRRF-UNESCO-Sunscreen-in-Jellyfish-Lake-no.2732.pdf">commissioned reports</a> which have found contamination from specific active ingredients in sunscreen in the water at beaches, rivers and lakes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/theres-insufficient-evidence-your-sunscreen-harms-coral-reefs-109567">There's insufficient evidence your sunscreen harms coral reefs</a>
</strong>
</em>
</p>
<hr>
<p>Notably, the nations and regions which have banned these active ingredients, like Bonaire and Mexico, have local economies heavily reliant on summer tourism. For these areas, coral bleaching is not only an environmental catastrophe but an economic loss as well, if tourists choose to go elsewhere.</p>
<h2>How do we know sunscreen isn’t the issue?</h2>
<p>So if contamination concerns over these active ingredients are warranted, how can we be sure they’re not the cause of the bleaching in the Great Barrier Reef? </p>
<p>Put simply, the concentrations of the chemicals are too low to cause the bleaching. </p>
<p>The synthetic ingredients used in most products are highly <a href="https://www.corrosionpedia.com/definition/653/hydrophobic#:%7E:text=Hydrophobic%20is%20a%20property%20of,Oils%20and%20fats%20are%20hydrophobic.">hydrophobic</a> and <a href="https://www.greenfacts.org/glossary/jkl/lipophilic.htm">lipophilic</a>. That means they shun water and love fats, making them hard to dissolve in water. They’d much prefer to stay in the skin until they break down.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/research-check-should-we-be-worried-that-the-chemicals-from-sunscreen-can-get-into-our-blood-116738">Research Check: should we be worried that the chemicals from sunscreen can get into our blood?</a>
</strong>
</em>
</p>
<hr>
<p>Because of this, the levels found in the environment are very low. How low? Think nanograms per litre (a nanogram is 0.000000001 grams) or micrograms per litre (a microgram is 0.00001 grams). Significantly higher levels are found only in waste water treatment sludge and some sediments, not in the water itself.</p>
<p>So how do we reconcile this with studies showing sunscreen can damage corals? Under laboratory conditions, many active ingredients in sunscreen have been found to damage corals as well as <a href="https://pubmed.ncbi.nlm.nih.gov/22828885/">mussels</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/17889917/#:%7E:text=BP%2D2%20was%20accumulated%20in,and%20female%20fish%20were%20observed.">fish</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/24359924/">small crustaceans</a>, and plant-like organisms such as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0269749111006713">algae and phytoplankton</a>.</p>
<p>The key phrase above is “under laboratory conditions”. While these studies would suggest sunscreens are a real threat to reefs, it’s important to know the context. </p>
<p>Studies like these are usually conducted under artificial conditions which can’t account for natural processes. They usually don’t account for the breakdown of the chemicals by sunlight or dilution through water flow and tides. These tests also use sunscreen concentrations up to thousands of times higher – milligrams per litre – compared to real world contamination levels found in collected samples.</p>
<p>In short, laboratory-only studies are not giving us a reliable indication of what happens to these chemicals in real world conditions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Sea wave seen side on" src="https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454298/original/file-20220325-21-1wft8gc.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">Laboratory studies don’t tend to account for dilution in seas or rivers.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>If it’s not sunscreen, what is it?</h2>
<p>The greatest threats to the reef are climate change, coastal development, land-based run-off like pesticides, herbicides, and other pollutants, and direct human use like illegal fishing, according to a <a href="https://www.gbrmpa.gov.au/our-work/outlook-report-2019">2019 outlook report</a> issued by the reef’s managing body. </p>
<p>Reefs get their striking colours from single-celled organisms called <a href="https://oceanservice.noaa.gov/education/tutorial_corals/coral02_zooxanthellae.html">zooxanthellae</a> which grow and live inside corals. Importantly, these organisms only grow under very specific conditions, including narrow bands of temperature and light levels. When conditions go outside the zooxanthellaes’ preferred zone, they die and the coral turns white. </p>
<p>As a result, the likeliest cause of this bleaching is <a href="https://www.gbrmpa.gov.au/our-work/threats-to-the-reef/climate-change">climate change</a>, which has increased ocean temperatures and acidity and resulted in more flooding, storms, and cyclones which block light and stir up the ocean floor. </p>
<p>So do you need to worry about the impact of your sunscreen on the environment? No. Sunscreen should remain a key part of our sun protection strategy, as a way to protect skin from UV damage, prevention skin cancers, and slow the visible signs of ageing. Our coral reefs face much bigger issues than sunscreen.</p><img src="https://counter.theconversation.com/content/179938/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Associate Professor Wheate in the past has received funding from the ACT Cancer Council, Tenovus Scotland, Medical Research Scotland, Scottish Crucible, and the Scottish Universities Life Sciences Alliance. He is Fellow of the Royal Australian Chemical Institute. Nial is the Science Director of Canngea Pty Ltd, chief scientific officer of Vairea Skincare LLC, a Board Director of the Australian Medicinal Cannabis Association, and a Standards Australia panel member for sunscreen agents.</span></em></p>Laboratory studies suggest sunscreen chemicals are dangerous to coral reefs. But in real world conditions, that’s not true. Bleaching must have another cause.Nial Wheate, Associate Professor of the Sydney Pharmacy School, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1788982022-03-23T19:07:01Z2022-03-23T19:07:01ZSaving the Great Barrier Reef: these recent research breakthroughs give us renewed hope for its survival<figure><img src="https://images.theconversation.com/files/453785/original/file-20220323-25-k2518z.jpg?ixlib=rb-1.1.0&rect=15%2C31%2C5160%2C3849&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">FNQ</span> <span class="attribution"><span class="source">Marie Roman </span>, <span class="license">Author provided</span></span></figcaption></figure><p>With yet another coral bleaching event underway on the Great Barrier Reef, we’re reminded of the tragic consequences of climate change. </p>
<p>Even if we manage to stop the planet warming beyond 1.5°C this century, <a href="https://theconversation.com/mass-starvation-extinctions-disasters-the-new-ipcc-reports-grim-predictions-and-why-adaptation-efforts-are-falling-behind-176693">scientists predict</a> up to 90% of tropical coral reefs will be severely damaged. </p>
<p>But we believe there’s a chance the Great Barrier Reef can still survive. What’s needed is ongoing, active management through scientific interventions, alongside rapid, enormous cuts to global greenhouse gas emissions. </p>
<p>In 2020, the federal government announced the <a href="https://gbrrestoration.org/">Reef Restoration and Adaptation Program</a>, which aims to help coral reefs adapt to the effects of warming oceans. It included <a href="https://theconversation.com/if-we-can-put-a-man-on-the-moon-we-can-save-the-great-barrier-reef-121052">research and development</a> funding into 35 cutting-edge technologies that could be deployed at large scale, from cloud brightening to seeding reefs with heat-tolerant corals. </p>
<p>Now, two years into the effort, we’re seeing a number of breakthroughs that bring us renewed hope for the reef’s future. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Coral in aquariums" src="https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453786/original/file-20220323-23-5njdpu.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">Coral aquaculture research at the National Sea Simulator.</span>
<span class="attribution"><span class="source">Roslyn Budd/Budd Photography</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Bleaching on the reef</h2>
<p>Aerial surveys of the entire reef are currently underway to determine the extent and severity of current bleaching. These should be complete before the end of March. </p>
<p>Meanwhile, United Nations’ reef monitoring delegates are visiting the Great Barrier Reef this week to determine whether its World Heritage status should be downgraded.</p>
<p>Early indications suggest bleaching is most severe in areas of greatest accumulated heat stress, particularly in the area around Townsville. In some places, water temperatures have reached <a href="https://www.climatecouncil.org.au/resources/dire-warning-great-barrier-reef-un-inspection-begins-climate-council-briefing/">3°C higher</a> than normal. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/adapt-move-or-die-repeated-coral-bleaching-leaves-wildlife-on-the-great-barrier-reef-with-few-options-179570">Adapt, move, or die: repeated coral bleaching leaves wildlife on the Great Barrier Reef with few options</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bleached coral" src="https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453788/original/file-20220323-17-hqiq7k.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">It seems bleaching is most severe in the area around Townsville.</span>
<span class="attribution"><span class="source">AIMS</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453789/original/file-20220323-21-133k5nm.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">Aerial surveys are underway to determine the extent and severity of current bleaching.</span>
<span class="attribution"><span class="source">LTMP</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Researchers involved in the Reef Restoration and Adaptation Program are examining a wide range of interventions to repair coral reefs. Unlike current reef restoration efforts, which are done by hand on a few square metres of reef, these interventions are designed to be applied at tremendous scales – across thousands of square kilometres.</p>
<p>Major scientific, technological, process, communication and management breakthroughs are required to see this become successful. We’re pleased to report that we’re already seeing the first successes, with others becoming more likely as research and development continues.</p>
<h2>Early success stories</h2>
<p>One key family of possible interventions involves culturing and deploying millions of heat-tolerant corals onto selected reefs. </p>
<p>Over the last two years, the research team has <a href="https://www.nature.com/articles/s41396-022-01203-0">accelerated the natural adaptation</a> of several coral species to warmer temperatures, allowing them to survive up to an additional four weeks of 1°C excess heat stress. We believe a total of eight weeks of 1°C excess heat stress can be achieved.</p>
<p>This level of additional heat tolerance can make a real difference for reef survival if we can limit greenhouse gas emissions driving climate change.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diver experimenting in the reef" src="https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453792/original/file-20220323-27-1opweqt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Reef interventions are designed to be applied across thousands of square kilometres.</span>
<span class="attribution"><span class="source">Marie Roman</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-we-can-put-a-man-on-the-moon-we-can-save-the-great-barrier-reef-121052">If we can put a man on the Moon, we can save the Great Barrier Reef</a>
</strong>
</em>
</p>
<hr>
<p>We’ve also developed <a href="https://www.researchgate.net/profile/Carly-Randall/publication/351513035_Enhancing_Coral_Survival_on_Deployment_Devices_With_Microrefugia/links/609b646f92851c490fd33269/Enhancing-Coral-Survival-on-Deployment-Devices-With-Microrefugia.pdf">novel seeding devices</a>, which allow mass delivery of juvenile corals to reefs in a way that enhances their survival, paving the way for larger field trials. </p>
<p>Seeding heat-tolerant corals onto the reef will require significant improvements in coral aquaculture – the process of raising healthy coral in an aquarium before transporting them to the Great Barrier Reef. While current methods are limited to producing and deploying a few thousand corals per year, new advanced methods are designed to produce tens of millions per year – faster and cheaper than ever before. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453784/original/file-20220323-23-1gwwqle.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">Advances in reef interventions must be paired with cuts to emissions.</span>
<span class="attribution"><span class="source">Roslyn Budd/Budd Photography</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Another breakthrough relates to the ongoing development of new models and the data to calibrate them. </p>
<p>These are set to vastly improve our ability to predict where interventions are best deployed, and how well they’ll function. Early modelling results suggest even at a modest scale, well-targeted interventions could be enough to shift the state of individual reefs from terminal decline to survival over several decades.</p>
<h2>4 conditions for lasting benefit</h2>
<p>For these early breakthroughs to bring lasting benefit at such tremendous scales, four key conditions must be met:</p>
<ol>
<li><p>interventions will have to be readily scalable and affordable. That means methods and technologies now being trialled in labs and on small patches of reef will have to be automated, mass-produced, up-sized and delivered in ways not previously considered feasible. All of this will take significant investment </p></li>
<li><p>interventions must be safe and acceptable to regulators and the public </p></li>
<li><p>a range of people, especially Traditional Owners of reef sea-country, must be involved in the effort. This includes through consultation, in decision-making and design</p></li>
<li><p>most importantly, global emissions must be brought rapidly under control, ideally to keep warming to under 1.5°C this century.</p></li>
</ol>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453790/original/file-20220323-25-1i9nfub.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">Much of the Great Barrier Reef was in the early stages of recovery following prior bleaching events.</span>
<span class="attribution"><span class="source">LTMP</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Grey fish swim over coral" src="https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453791/original/file-20220323-27-ab8o2u.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 healthy Great Barrier Reef is home to at least 1,625 species of fish.</span>
<span class="attribution"><span class="source">LTMP</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Over the coming months, the program will be conducting more trials on the reef. Alongside recent advances by other programs, such as approaches to control coral-eating crown of thorns starfish, there’s now real promise that a combined intervention at scale can be successful. </p>
<h2>Saving the reef</h2>
<p>Imagine a world where coral reefs have largely disappeared from the world. The few remaining reefs are a shadow of what they once were: grey, broken, covered in weeds and devoid of colourful fish. </p>
<p>Millions of people who’ve depended on reefs must turn to other livelihoods, which may contribute to <a href="https://theconversation.com/mass-starvation-extinctions-disasters-the-new-ipcc-reports-grim-predictions-and-why-adaptation-efforts-are-falling-behind-176693">climate-related migration</a>. Imagine, too, how we’d feel knowing it could have been prevented.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453793/original/file-20220323-19-1tl8evu.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">The program will be conducting more on-reef trials in coming months.</span>
<span class="attribution"><span class="source">Marie Roman</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We are hopeful for an alternative vision for the future of the world’s reefs. It’s one in which the amazing beauty and diversity, and the huge global economic benefits, are intact and thriving well into the next century.</p>
<p>The difference between these two possible futures depends on choices we make right now. To save our reefs, we must simultaneously mitigate global warming and adapt to impacts already locked in. Neither alone will be enough. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mass-starvation-extinctions-disasters-the-new-ipcc-reports-grim-predictions-and-why-adaptation-efforts-are-falling-behind-176693">Mass starvation, extinctions, disasters: the new IPCC report’s grim predictions, and why adaptation efforts are falling behind</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/178898/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>AIMS receives funding from the Commonwealth Government for its work on reef adaptation, directly and through the Reef Trust Partnership with the Great Barrier Reef Foundation.</span></em></p><p class="fine-print"><em><span>Rob Vertessy is an independent chair of the Reef Restoration and Adaptation Program governing board, a role for which he is remunerated.
</span></em></p>Coral in the Great Barrier Reef is once again bleaching, with water temperatures up to 3°C higher than normal in some places.Paul Hardisty, CEO, Australian Institute of Marine ScienceDavid Mead, Executive Director of Strategic Development at Australian Institute of Marine Science, Australian Institute of Marine ScienceRob Vertessy, Enterprise Professor in the School of Engineering, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1795702022-03-21T07:46:12Z2022-03-21T07:46:12ZAdapt, move, or die: repeated coral bleaching leaves wildlife on the Great Barrier Reef with few options<figure><img src="https://images.theconversation.com/files/453230/original/file-20220321-17-17ioogu.jpg?ixlib=rb-1.1.0&rect=22%2C97%2C3811%2C1965&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Grumpy Turtle Films</span>, <span class="license">Author provided</span></span></figcaption></figure><p>To our horror, another mass coral bleaching event may be striking the Great Barrier Reef, with water temperatures reaching up to <a href="https://www.climatecouncil.org.au/resources/dire-warning-great-barrier-reef-un-inspection-begins-climate-council-briefing/">3°C higher</a> than average in some places. This would be the sixth such event since the late 1990s, and the fourth since 2016. </p>
<p>It comes as a monitoring mission from the United Nations arrives in Queensland today to inspect the reef and <a href="https://theconversation.com/not-declaring-the-great-barrier-reef-as-in-danger-only-postpones-the-inevitable-164867">consider listing</a> the World Heritage site as “in danger”. </p>
<p>As coral reef scientists, we’ve seen firsthand how the Great Barrier Reef is nearing its <a href="https://theconversation.com/what-climate-tipping-points-are-and-how-they-could-suddenly-change-our-planet-49405">tipping point</a>, beyond which the reef will lose its function as a viable ecosystem. This is not only due to climate change exacerbating marine heatwaves, but also higher ocean acidity, loss of oxygen, pollution, and more. </p>
<p>Scientists are at our own tipping points, too. The reef is suffering environmental conditions so extreme, we’re struggling to simulate these scenarios in our laboratories. Even though Australia has <a href="https://www.aims.gov.au/seasim">world-class facilities</a>, we are proverbially beating our heads against the wall each year as conditions worsen. </p>
<p>It’s getting harder for scientists to predict how these conditions will affect individual species, let alone the health and biodiversity of reef ecosystems. But let’s explore what we do know. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=396&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=396&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453238/original/file-20220321-17-y02711.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=396&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coral bleaching seen due to the current marine heatwave.</span>
<span class="attribution"><span class="source">Grumpy Turtle Films</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>What is coral bleaching and why does it happen?</h2>
<p>Corals are animals that live in a mutually beneficial partnership with tiny single-celled algae called “zooxanthellae” (but scientists call them zooks). </p>
<p>Zooks benefit corals by giving them energy and colour, and in return the coral gives them a home in the coral tissue. Under stress, such as in too-hot water, the algae produce toxins instead of nutrition, and the coral ejects them. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-major-heatwaves-in-30-years-have-turned-the-great-barrier-reef-into-a-bleached-checkerboard-170719">5 major heatwaves in 30 years have turned the Great Barrier Reef into a bleached checkerboard</a>
</strong>
</em>
</p>
<hr>
<p>Without the algae, the corals begin to starve. They lose their vibrant colours, revealing the bright white limestone skeleton through the coral tissue. </p>
<p>If stress conditions abate, the algae can return and coral can recover over months. But if stress persists, the corals can die – the skeletons begin to crumble, removing vital habitat for other species. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=313&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=313&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=313&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=393&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=393&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453239/original/file-20220321-23-1k97j5m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=393&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Water temperatures reaching up to 3°C higher than average in some places.</span>
<span class="attribution"><span class="source">Grumpy Turtle Films</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>We had hoped for a reprieve</h2>
<p>Scientists and managers had hoped for a reprieve this year. Much of the Great Barrier Reef was <a href="https://theconversation.com/5-major-heatwaves-in-30-years-have-turned-the-great-barrier-reef-into-a-bleached-checkerboard-170719">in the early stages of recovery</a> following the 2016, 2017, and 2020 bleaching events.</p>
<p>In the tropical paradise of northern Queensland, we’ve been wishing for cloudy days and cooler temperatures, hoping for rain and even storms (but not big ones). These conditions typically come with La Niña – a natural climate phenomenon associated with cooler, wetter weather, which has now happened <a href="https://theconversation.com/back-so-soon-la-nina-heres-why-were-copping-two-soggy-summers-in-a-row-173684">two years in a row</a>. </p>
<p>But despite these effects of La Niña, climate change meant <a href="https://theconversation.com/2021-was-one-of-the-hottest-years-on-record-and-it-could-also-be-the-coldest-well-ever-see-again-175238%22%22">2021 was one of the hottest years on record</a>. Now, at the tail end of Australia’s summer, the reef is experiencing another marine heatwave and is tipping over the bleaching threshold. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1505058856941998086"}"></div></p>
<p>There’s not enough time for coral to recover between events. Even the most robust corals require <a href="https://doi.org/10.1098/rspb.2018.2908">nearly a decade to recover</a>. There is also no clear evidence corals are adapting to the new conditions.</p>
<p>To make matters worse, climate change is supercharging the atmosphere and making even the natural variations of <a href="https://research.noaa.gov/article/ArtMID/587/ArticleID/2685/New-research-volume-explores-future-of-ENSO-under-influence-of-climate-change">La Niña and its counterpart El Niño more variable and less predictable</a>. This means Australia will not only endure more intense heatwaves, but also flooding, droughts and storms. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=395&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=395&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453240/original/file-20220321-15-cdocak.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=395&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">At least 1,625 species of fishes live in the Great Barrier Reef.</span>
<span class="attribution"><span class="source">Grumpy Turtle Films</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>How will this hurt marine life?</h2>
<p>A healthy Great Barrier Reef <a href="https://www.gbrmpa.gov.au/the-reef/animals#:%7E:text=1625%20species%20of%20fish%2C%20including,3000%20species%20of%20molluscs%20(shells)">is home to</a> at least 1,625 species of fishes, 3,000 species of molluscs, 630 species of echinoderms (such as sea stars and urchins), and the list goes on.</p>
<p>Marine life in coral reefs have three options in warming waters: adapt, move, or die. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=396&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=396&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453241/original/file-20220321-15-17tqh2m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=396&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most shark species can’t adapt to warmer waters fast enough to survive.</span>
<span class="attribution"><span class="source">Grumpy Turtle Films</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><strong>1. Can they adapt?</strong> </p>
<p>Over generations, species can make changes at the molecular level – their DNA – so they’re more suited to or can adapt to new environmental conditions. This evolution may be possible for species with fast generation times, such as <a href="https://doi.org/10.1111/gcb.13419">damselfishes</a>.</p>
<p>But reef species with slower generation times can’t keep pace with the rate we’re changing their habitat conditions. This includes the iconic <a href="https://doi.org/10.2305%2FIUCN.UK.2018-2.RLTS.T132773A100561780.en">potato cod</a> and most sharks, which take a around a decade or longer to reach sexual maturity.</p>
<p><strong>2. Can they move?</strong> </p>
<p><a href="https://doi.org/10.1111/gcb.13488">Some species of reef fishes</a> may start moving to cooler waters before the harmful effects of warming take hold. </p>
<p>But this option isn’t available to all species, such as those that depend on a particular habitat, certain resources, or protection. This includes coral, as well as <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2004.00839.x">coral-dwelling gobies</a> and <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2007.01341.x">several damselfishes</a>. </p>
<p>A citizen science project called <a href="https://www.redmap.org.au/">Project RedMap</a>, has been documenting <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/faf.12036">the poleward migration of reef fish species</a> due to climate change. <a href="https://doi.org/10.1111/faf.12036">Studies have found</a> that larger, tropical fishes with a high swimming ability are more likely to survive in temperate waters, such as some butterflyfishes.</p>
<p><strong>3. They can die</strong></p>
<p>The third option is one we don’t like to talk about, but is becoming more of a threat. </p>
<p>If marine life can’t adapt or move , we’ll see <a href="https://theconversation.com/almost-60-coral-species-around-lizard-island-are-missing-and-a-great-barrier-reef-extinction-crisis-could-be-next-163714">extinctions at a local scale</a>, total extinction of some species, and dramatic declines in fish populations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=395&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=395&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453242/original/file-20220321-13-wwbv8w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=395&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">UNESCO representatives are visiting the reef to assess its World Heritage status.</span>
<span class="attribution"><span class="source">Grumpy Turtle Films</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Listing the reef as ‘in danger’</h2>
<p>While the reef is bleaching, UNESCO delegates have arrived in Queensland to monitor its health, as the World Heritage site is once again being considered for an “<a href="https://whc.unesco.org/en/158/">in danger</a>” listing. </p>
<p>The visit will likely include seeing the bleaching currently occurring, the damage to the reef still apparent from past events, and they’ll hear firsthand from scientists and managers who’ve witnessed these impacts. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"926001558747193344"}"></div></p>
<p>Listing the Great Barrier Reef as “in danger” would raise the alert level for the international community and hopefully inspire climate action. </p>
<p>Reducing the major source of stress the reef faces – climate change – will require ongoing collaborations between Australian and international governments, with work on local management issues also involving business owners, reef managers, Traditional Owners, scientists, civil society groups, and other stakeholders.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-1-billion-great-barrier-reef-funding-is-nonsensical-australians-and-their-natural-wonder-deserve-so-much-better-175924">The $1 billion Great Barrier Reef funding is nonsensical. Australians, and their natural wonder, deserve so much better</a>
</strong>
</em>
</p>
<hr>
<p>We’ve known for a long time the most important step to save the reef: cutting emissions to stop global warming. Indeed, <a href="https://www.publish.csiro.au/mf/MF99078">future projections</a> of coral bleaching from the 1990s suggested that frequent and severe events would begin from the late-2010s – and they’ve been alarmingly prescient.</p>
<p>The Great Barrier Reef’s continuing demise is one of the most visible examples of how our inaction as humans has profound and perhaps irreversible consequences. We are rapidly accelerating toward the tipping point.</p><img src="https://counter.theconversation.com/content/179570/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jodie L. Rummer receives funding from the Australian Research Council Centre of Excellence for Coral Reef Studies. </span></em></p><p class="fine-print"><em><span>Scott Heron receives funding from Australian Research Council and NASA ROSES Ecological Forecasting.</span></em></p>The reef is suffering environmental conditions that are so extreme, scientists are struggling to simulate these scenarios in laboratories.Jodie L. Rummer, Associate Professor & Principal Research Fellow, James Cook UniversityScott F. Heron, Associate Professor in Physics, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1760842022-02-01T19:01:55Z2022-02-01T19:01:55ZSafe havens for coral reefs will be almost non-existent at 1.5°C of global warming – new study<figure><img src="https://images.theconversation.com/files/443717/original/file-20220201-27-7t8bbg.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3409%2C2270&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/sun-rays-filtering-through-water-1655309398">Ajit S N/Shutterstock</a></span></figcaption></figure><p>Coral reefs have <a href="https://www.nature.com/articles/nclimate1674">long been regarded</a> as one of the earliest and most significant ecological casualties of global warming. In <a href="https://doi.org/10.1371/journal.pclm.0000004">new research</a> published in the journal PLOS Climate, we found that the future of these tropical ecosystems – thought to harbour <a href="https://www.iucn.org/resources/issues-briefs/coral-reefs-and-climate-change">more species than any other</a> – is probably worse than anticipated.</p>
<p>Climate change is causing more frequent <a href="https://theconversation.com/uk/topics/marine-heatwaves-39175">marine heatwaves</a> worldwide. Corals have adapted to live in a specific temperature range, so when ocean temperatures are too hot for a prolonged period, corals can bleach – losing the colourful algae that live within their tissue and nourish them via photosynthesis – and may eventually die. </p>
<p>Across the tropics, <a href="https://www.nature.com/articles/nature22901">mass bleaching and die-offs</a> have gone from being rare to a somewhat regular occurrence as the climate has warmed. More frequent heatwaves mean that the time corals have to recover is getting shorter.</p>
<figure class="align-center ">
<img alt="A boulder coral on a reef that has bleached white." src="https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443703/original/file-20220201-15-1sq3ipg.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">Bleached corals are more vulnerable to disease and starvation.</span>
<span class="attribution"><span class="source">Maria Beger</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In a 2018 report, the Intergovernmental Panel on Climate Change predicted that 1.5°C of global warming would cause <a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2019/02/SR15_Chapter3_Low_Res.pdf">between 70 and 90%</a> of the world’s coral reefs to disappear. Now, with models capable of examining temperature differences between coral reefs one kilometre apart, our team found that at 1.5°C of warming, which the world is predicted to reach in the <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/">early 2030s</a> without drastic action to limit greenhouse gas emissions, 99% of the world’s reefs will experience heatwaves that are too frequent for them to recover.</p>
<p>That would spell catastrophe for the thousands of species that depend on coral reefs, as well as the roughly <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/9461/-Marine%20and%20Coastal%20Ecosystems%20and%20Human%20Well-Being_%20A%20synthesis%20report%20based%20on%20the%20findings%20of%20the%20Millennium%20Ecosystems%20Assessment-2006652.pdf?sequence=3&%3BisAllowed=">one billion people</a> whose livelihoods and food supply benefits from coral reef biodiversity. </p>
<h2>Thermal refugia</h2>
<p>The thermal stress of a heatwave can affect corals over a <a href="https://www.science.org/doi/10.1126/science.aan8048">huge geographic area</a>, like the entire northern Great Barrier Reef or archipelagos like the Maldives. A marine heatwave in 2015-16 <a href="https://www.science.org/doi/10.1126/science.aan8048">caused widespread bleaching</a> in each of the Pacific, Atlantic and Indian Oceans. </p>
<p>Corals are small polyp-like animals that form colonies of thousands by secreting a calcium carbonate skeleton that builds a reef. Corals grow slowly, so their recovery following bleaching and die-offs can take a long time and can be hampered by pollution and overfishing. Some species grow faster and are more capable of recovering quicker.</p>
<p>Scientists hope that <a href="https://www.sciencedirect.com/science/article/pii/S000632071300284X">local conditions</a> on some reef tracts will ensure <a href="https://academic.oup.com/icesjms/article/75/1/43/4080230?login=true">suitable temperatures</a> for corals in the future, even when surrounding areas warm. These conditions may be possible due to upwelling, where cooler water is brought to the surface, or strong ocean currents. Reef managers can <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.12587">prioritise</a> these so-called refugia, which offer corals a greater chance of survival. </p>
<figure class="align-center ">
<img alt="A sunlit coral reef populated by lots of tropical fish." src="https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443702/original/file-20220201-14-1ol29sx.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">Healthy reefs can support a vast array of life.</span>
<span class="attribution"><span class="source">Maarten De Brauwer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Finding these refugia is difficult, though, as they are likely to be small and the resolution of climate projections that model changes in ocean temperatures over time tend to be too coarse. Our team increased the resolution of climate model projections by downscaling them with historical data from satellite observations to find out where refugia are likely to persist in the future. </p>
<p>We found that, from 1986 to 2019, 84% of the world’s reefs offered sufficient thermal refuge. This meant corals had enough time to recover in between bleaching events. With 1.5°C of global warming above pre-industrial levels, only 0.2% of these refugia remain. At 2°C of warming, safe havens from heat for coral reefs will no longer exist.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two world maps comparing coral reef refugia 1986-2019 versus at 1.5°C." src="https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443790/original/file-20220201-15324-1ilqrsk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Most of the world’s reef refugia disappear at 1.5°C.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1371/journal.pclm.0000004">Dixon et al. (2022)/PLOS Climate</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1002/essoar.10510201.1">Preliminary findings</a> from another study (yet to complete the peer-review process) would seem to confirm the catastrophic effects of 1.5°C of global warming on coral reefs. This research was carried out independently by scientists in the US using a different method but the same climate models and spatial resolutions.</p>
<h2>The future of coral reefs</h2>
<p>Global warming of 1.5°C is the lower limit that world leaders aspired to maintain when they signed the Paris agreement in 2015. This target is moving <a href="https://unfccc.int/sites/default/files/resource/cma2021_08r01_E.pdf">further out of reach</a>. For coral reefs, there is no safe limit to global warming. Given the rate at which the global average temperature is increasing, marine heatwaves are likely to become so frequent that most of the world’s coral reefs will experience intolerable heat stress regularly. Most reefs have already experienced at least one such event this decade.</p>
<p>Not all regions are stressed at the same time as heatwaves are not global, nor do all corals bleach. Some <a href="https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1461-0248.2001.00203.x%22">coral species</a> are more capable of coping with extreme temperatures than others due to their <a href="https://link.springer.com/article/10.1007/s00338-018-1702-1">growth form</a> or the <a href="https://link.springer.com/content/pdf/10.1007/s00338-010-0696-0.pdf">type of algae</a> within their tissue. Still, the magnitude and frequency of heatwaves predicted in this study will probably affect even resistant coral species, suggesting the world will lose most of its reef biodiversity. Coral reefs of the future are likely to look very different to the colourful and diverse ecosystems we know today. </p>
<figure class="align-center ">
<img alt="An underwater field of coral rubble smothered in algae." src="https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443778/original/file-20220201-25-a80n1z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A dead coral reef.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dead-coral-reef-killed-by-global-461420095">Rich Carey/Shutterstock</a></span>
</figcaption>
</figure>
<p>Climate change is already <a href="https://www.nature.com/articles/nature22901">degrading coral reefs globally</a>. Now we know that protecting the last remaining temperature refuges will not work on its own. Slashing greenhouse gas emissions this decade is the best hope for saving what remains.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Adele Dixon receives funding from NERC (UKRI). </span></em></p><p class="fine-print"><em><span>Maria Beger receives funding from NERC (UKRI). </span></em></p><p class="fine-print"><em><span>Peter Kalmus receives funding from NASA.</span></em></p><p class="fine-print"><em><span>Scott F. Heron receives funding from the Australian Research Council and NASA ROSES Ecological Forecasting.</span></em></p>Marine heatwaves will happen so often that reefs will struggle to weather successive bleaching events.Adele Dixon, PhD Candidate in Coral Biology, University of LeedsMaria Beger, Associate Professor in Conservation Science, University of LeedsPeter Kalmus, Data Scientist, NASAScott F. Heron, Associate Professor in Physics, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1752262022-01-25T19:03:20Z2022-01-25T19:03:20ZSome endangered species can no longer survive in the wild. So should we alter their genes?<figure><img src="https://images.theconversation.com/files/442159/original/file-20220124-17-fdh2zz.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1650%2C930&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Melbourne Zoo</span></span></figcaption></figure><p>Around the world, populations of many beloved species are declining at increasing rates. According to one <a href="https://www.theguardian.com/environment/2020/sep/30/world-plant-species-risk-extinction-fungi-earth">grim projection</a>, as many as 40% of the world’s species may be extinct by 2050. Alarmingly, many of these declines are caused by threats for which few solutions exist.</p>
<p>Numerous species now depend on conservation breeding programs for their survival. But these programs typically do not encourage species to adapt and survive in the wild alongside intractable threats such as climate change and disease.</p>
<p>This means some species can no longer exist in the wild, which causes major downstream effects on the ecosystem. Consider, for example, how a coral reef would struggle to function without corals.</p>
<p>What if there was another way? My colleagues and I have developed an intervention method that aims to give endangered species the genetic features they need to survive in the wild.</p>
<figure class="align-center ">
<img alt="bleached coral with fish" src="https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&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">Genetically altering coral may help them survive in a warmer world.</span>
<span class="attribution"><span class="source">Rick Stuart-Smith</span></span>
</figcaption>
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<h2>Bringing theory into practice</h2>
<p>Over generations, natural selection enables species to adapt to threats. But in many instances today, the speed at which threats are developing is outpacing species’ ability to adapt. </p>
<p>This problem is especially apparent in wildlife threatened by newly emerging infectious diseases such as chytridiomycosis in amphibians, and in climate-affected species such as corals. </p>
<p>The toolkit my colleagues and I developed is called “targeted genetic intervention” or TGI. It works by increasing the occurrence or frequency of genetic features that impact an organism’s fitness in the presence of the threat. We outline the method in a recent <a href="https://www.sciencedirect.com/science/article/abs/pii/S0169534721003384">research paper</a>.</p>
<p>The toolkit involves <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/artificial-selection">artificial selection</a> and <a href="https://www.frontiersin.org/articles/10.3389/fbioe.2019.00175/full">synthetic biology</a>. These tools are well established in agriculture and medicine but relatively untested as conservation tools. We explain them in more detail below.</p>
<p>Many tools in our TGI toolkit have been discussed in theory in conservation literature in recent decades. But rapid developments in genome sequencing and synthetic biology mean some are now possible in practice.</p>
<p>The developments have made it easier to understand the genetic basis of features which enable a species to adapt, and to manipulate them.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/we-name-the-26-australian-frogs-at-greatest-risk-of-extinction-by-2040-and-how-to-save-them-166339">We name the 26 Australian frogs at greatest risk of extinction by 2040 — and how to save them</a>
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<figure class="align-center ">
<img alt="frog on wet rock" src="https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442166/original/file-20220124-19-xc82dx.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">Some animal species cannot adapt in time to survive threats such as disease.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<h2>What is artificial selection?</h2>
<p>Humans have long used artificial (or phenotypic) selection to promote desirable characteristics in animals and plants raised for companionship or food. This genetic alteration has led to organisms, such as domestic dogs and maize, that are dramatically different from their wild progenitors.</p>
<p>Traditional artificial selection can lead to outcomes, such as high inbreeding rates, that affect the health and resilience of the organism and are undesirable for conservation. If you’ve ever owned a purebred dog, you might be aware of some of these genetic disorders.</p>
<p>And when it comes to conservation, determining which individuals from a species are resistant to, say, a deadly pathogen would involve exposing the animal to the threat – clearly not in the interests of species preservation.</p>
<p>Scientists in the livestock industry have developed a new approach to circumvent these problems. Called genomic selection, it combines data from laboratory work (such as a disease trial) with the genetic information of the animals to predict which individuals bear genetic features conducive to adaptation. </p>
<p>These individuals are then chosen for breeding. Over subsequent generations, a population’s ability to survive alongside pervasive threats increases.</p>
<p>Genomic selection has led to disease-resistant salmon and livestock that produce more milk and better tolerate heat. But it is yet to be tested in conservation.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-this-little-marsupials-poo-nurtures-urban-gardens-and-bushland-and-how-you-can-help-protect-them-175064">How this little marsupial's poo nurtures urban gardens and bushland (and how you can help protect them)</a>
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<figure class="align-center ">
<img alt="cows in green field" src="https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442161/original/file-20220124-27-11vyq0z.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">Artificial selection has been used to develop traits that humans desire in livestock.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<h2>What is synthetic biology?</h2>
<p><a href="https://www.genome.gov/about-genomics/policy-issues/Synthetic-Biology">Synthetic biology</a> is a toolkit for promoting change in organisms. It includes methods such as transgenesis and gene editing, which can be used to introduce lost or novel genes or tweak specific genetic features. </p>
<p>Recent synthetic biology tools such as <a href="https://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/">CRISPR-Cas9</a> have created a buzz in the medical world, and are also starting to gain the <a href="https://portals.iucn.org/library/node/48408">attention</a> of conservation biologists.</p>
<p>Such tools can accurately tweak targeted genetic features in an individual organism – making it more able to adapt – while leaving the rest of the genome untouched. The genetic modifications are then passed on to subsequent generations.</p>
<p>The method reduces the likelihood of unintended genetic changes that can occur with artificial selection.</p>
<p>Synthetic biology methods are currently being trialled for conservation in multiple species around the world. These include the <a href="https://www.esf.edu/chestnut/resistance.htm">chestnut tree</a> and black-footed <a href="https://neo.life/2021/05/cloning-wildlife-and-editing-their-genes-to-protect-them-and-us/">ferrets</a> in the United States, and <a href="https://theconversation.com/gene-editing-is-revealing-how-corals-respond-to-warming-waters-it-could-transform-how-we-manage-our-reefs-143444">corals</a> in Australia.</p>
<p>I am working with researchers at the University of Melbourne to develop TGI approaches in Australian frogs. We are trialling these approaches in the iconic southern corroboree frog, and plan to extend them to other species if they prove effective.</p>
<p>Worldwide, the disease chytridiomycosis is devastating frog populations. Caused by the fungal pathogen <em>Batrachochytrium dendrobatidis</em>, it has led to the extinction of about <a href="https://www.nationalgeographic.com/animals/article/amphibian-apocalypse-frogs-salamanders-worst-chytrid-fungus">90 frog species</a> and declines in as many as 500 others.</p>
<p>Many frog species now rely on conservation breeding for their continued survival. No effective solution for restoring chytrid-susceptible frogs to the wild exists, because the fungus cannot be eradicated.</p>
<figure class="align-center ">
<img alt="gloved hand removed portion of DNA strand" src="https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442155/original/file-20220124-23-cebr8a.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">CRISPR technology could potentially be used to edit the genes of endangered species.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Looking ahead</h2>
<p>As with many conservation approaches, targeted genetic intervention is likely to involve trade-offs. For example, genetic features that make a species resistant to one disease may make it more susceptible to another.</p>
<p>But the rapid rate of species declines means we should trial such potential solutions before it’s too late. The longer species are absent from an ecosystem, the greater the chance of irreversible environmental changes. </p>
<p>Any genetic intervention of this type should involve all stakeholders, including Indigenous peoples and local communities. And caution should be taken to ensure species are fit for release and pose no risk to the environment.</p>
<p>By bringing the concept of TGI to the attention of the public, government, and other scientists, we hope we will spur discussion and encourage research on its risks and benefits.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-major-heatwaves-in-30-years-have-turned-the-great-barrier-reef-into-a-bleached-checkerboard-170719">5 major heatwaves in 30 years have turned the Great Barrier Reef into a bleached checkerboard</a>
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<img src="https://counter.theconversation.com/content/175226/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tiffany Kosch is a member of One Health Research Group at the University of Melbourne. Her research is currently funded by the Australian Research Council (grants FT190100462 and LP200301370). Additionally, the genome of their target species, the Southern Corroboree frog is currently being sequenced at no cost to the group by the Vertebrate Genomes Project. </span></em></p>The rapid rate of species declines means we should trial potential solutions before it’s too late.Tiffany Kosch, Research Fellow, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1707192021-11-05T00:16:24Z2021-11-05T00:16:24Z5 major heatwaves in 30 years have turned the Great Barrier Reef into a bleached checkerboard<p>Just 2% of the Great Barrier Reef remains untouched by bleaching since 1998 and 80% of individual reefs have bleached severely once, twice or three times since 2016, <a href="https://www.sciencedirect.com/science/article/abs/pii/S0960982221014901">our new study</a> reveals today. </p>
<p>We measured the impacts of five marine heatwaves on the Great Barrier Reef over the past three decades: in 1998, 2002, 2016, 2017 and 2020. We found these bouts of extreme temperatures have transformed it into a checkerboard of bleached reefs with very different recent histories. </p>
<p>Whether we still have a functioning Great Barrier Reef in the decades to come depends on how much higher we allow global temperatures to rise. The bleaching events we’ve already seen in recent years are a result of the world warming by 1.2°C since pre-industrial times. </p>
<p>World leaders meeting at the climate summit in Glasgow must commit to more ambitious promises to drastically cut greenhouse gas emissions. It’s vital for the future of corals reefs, and for the hundreds of millions of people who depend on them for their livelihoods and food security.</p>
<h2>Coral in a hotter climate</h2>
<p>The Great Barrier Reef is comprised of more than 3,000 individual reefs stretching for <a href="https://www.gbrmpa.gov.au/the-reef/reef-facts">2,300 kilometres</a>, and supports more than 60,000 jobs in reef <a href="https://www.gbrmpa.gov.au/our-work/Managing-multiple-uses/tourism-on-the-great-barrier-reef">tourism</a>. </p>
<p>Under climate change, the frequency, intensity and scale of climate extremes is changing rapidly, including the record-breaking marine heatwaves that cause corals to bleach. Bleaching is a stress response by overheated corals, where they lose their colour and many struggle to survive. </p>
<p>If all new COP26 pledges by individual countries are actually met, then the projected increase in average global warming could be brought down <a href="https://www.climate-resource.com/tools/ndcs">to 1.9°C</a>. In theory, this would put us in line with the goal of the Paris Agreement, which is to keep global warming below 2°C, but preferably 1.5°C, this century. </p>
<p>However, it is still not enough to prevent the <a href="https://www.ipcc.ch/sr15/chapter/spm/">ongoing degradation</a> of the world’s coral reefs. The damage to coral reefs from anthropogenic heating so far is very clear, and further warming will continue to <a href="https://www.science.org/doi/10.1126/science.aan8048">ratchet down</a> reefs throughout the tropics. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/not-declaring-the-great-barrier-reef-as-in-danger-only-postpones-the-inevitable-164867">Not declaring the Great Barrier Reef as 'in danger' only postpones the inevitable</a>
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</em>
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<h2>Ecological memories of heatwaves</h2>
<p>Most reefs today are in early <a href="https://www.aims.gov.au/reef-monitoring/gbr-condition-summary-2020-2021">recovery mode</a>, as coral populations begin to re-build since they last experienced bleaching in 2016, 2017 and 2020. It takes about a decade for a decent recovery of the fastest growing corals, and much longer for slow-growing species. Many coastal reefs that were severely bleached in 1998 have never fully recovered. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=523&fit=crop&dpr=1 754w, https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=523&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/430169/original/file-20211104-19-1po1sc2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=523&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 fringing reef flat at Orpheus Island on the central Great Barrier Reef, prior to mass coral bleaching in 1998.</span>
<span class="attribution"><span class="source">Bette Willis and Andrew Baird</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=478&fit=crop&dpr=1 600w, https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=478&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=478&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=601&fit=crop&dpr=1 754w, https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=601&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/430168/original/file-20211104-27-16wyz5j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=601&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 same reef flat at Orpheus Island after further bleaching in 2002 and 2016.</span>
<span class="attribution"><span class="source">Bette Willis and Andrew Baird</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Each bleaching event so far has a different geographic footprint. Drawing upon <a href="https://www.mdpi.com/2072-4292/6/11/11579">satellite data</a>, we measured the duration and intensity of heat stress that the Great Barrier Reef experienced each summer, to explain why different parts were affected during all five events. </p>
<p>The bleaching responses of corals differed greatly in each event, and was strongly influenced by the recent history of previous bleaching. For this reason, it’s important to measure the extent and severity of bleaching directly, where it actually occurs, and not rely exclusively on water temperature data from satellites as an indirect proxy.</p>
<p>We found the most vulnerable reefs each year were the ones that had not bleached for a decade or longer. On the other hand, when successive episodes were close together in time (one to four years apart), the heat threshold for severe bleaching increased. In other words, the earlier event had hardened regions of the Great Barrier Reef to subsequent impacts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bleached coral" src="https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/430176/original/file-20211104-15-noksid.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">Bleaching is a stress response by overheated corals.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>For example, in 2002 and 2017, it took much more heat to trigger similar levels of bleaching that were measured in 1998 and 2016. The threshold for bleaching was much higher on reefs that had experienced an earlier episode of heat stress.</p>
<p>Similarly, southern corals, which escaped bleaching in 2016 and 2017, were the most vulnerable in 2020, compared to central and northern reefs that had bleached severely in previous events.</p>
<p>Many different mechanisms could generate these historical effects, or ecological memories. One is <a href="https://www.nature.com/articles/s41586-018-0041-2">heavy losses</a> of the more heat-susceptible coral species during an earlier event – dead corals don’t re-bleach.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197">We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy</a>
</strong>
</em>
</p>
<hr>
<h2>Nowhere left to hide</h2>
<p>Only a single cluster of reefs remains unbleached in the far south, downstream from the rest of the Great Barrier Reef, in a small region that has remained consistently cool through the summer months during all five mass bleaching events. These reefs lie at the outer edge of the Great Barrier Reef, where upwelling of cool water may offer some protection from heatwaves, at least so far.</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=657&fit=crop&dpr=1 600w, https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=657&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=657&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=826&fit=crop&dpr=1 754w, https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=826&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/430397/original/file-20211104-23-29h946.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=826&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the Great Barrier Reef showing the cumulative level of bleaching observed in 2016, 2017 and 2020. The colours represent the intensity of bleaching, ranging from zero (category 1, dark blue) to severe bleaching that affected more than 60% of corals (category 4, red)</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>In theory, a judiciously placed network of well-protected, climate-resistant reefs might help to repopulate the <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/conl.12587">broader seascape</a>, if greenhouse gas emissions are curtailed to stabilise temperatures later this century. </p>
<p>But the unbleached southern reefs are too few in number, and too far away from the rest of the Great Barrier Reef to produce and deliver sufficient coral larvae, to promote a long-distance recovery. </p>
<p>Instead, future replenishment of depleted coral populations is more likely to be local. It would come from the billions of larvae produced by recovering adults on nearby reefs that have not bleached for a while, or by corals inhabiting reef in deeper waters which tend to experience less heat stress than those living in shallow water. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/this-situation-brings-me-to-despair-two-reef-scientists-share-their-climate-grief-123520">'This situation brings me to despair': two reef scientists share their climate grief</a>
</strong>
</em>
</p>
<hr>
<p>Future recovery of corals will increasingly be temporary and incomplete, before being interrupted again by the inevitable next bleaching event. Consequently, the patchiness of living coral on the Great Barrier Reef will increase further, and corals will continue to decline under climate change.</p>
<p>Our findings make it clear we no longer have the luxury of studying individual climate-related events that were once unprecedented, or very rare. Instead, as the world gets hotter, it’s increasingly important to understand the effects and combined outcomes of sequences of rapid-fire catastrophes.</p><img src="https://counter.theconversation.com/content/170719/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Terry Hughes receives funding from The Australian Research Foundation. </span></em></p><p class="fine-print"><em><span>Sean Connolly has received funding from the Australian Research Councilfor research including effects of climate change on coral reefs, and he currently receives funding from the Mark and Rachel Rohr foundation for work on climate resilience in the Tropical East Pacific.
</span></em></p>New research shows just 2% of the Great Barrier Reef remains untouched by bleaching since 1998. Its future survival depends on how much higher we allow global temperatures to rise.Terry Hughes, Distinguished Professor, James Cook UniversitySean Connolly, Research Biologist, Smithsonian InstitutionLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1660312021-08-16T19:50:16Z2021-08-16T19:50:16ZThere’s no end to the damage humans can wreak on the climate. This is how bad it’s likely to get<p>A major new <a href="https://www.ipcc.ch/report/ar6/wg1/">report</a> published last week by the Intergovernmental Panel on Climate Change (IPCC) contained grave warnings on where Earth’s climate is headed. So what happens if humanity doesn’t get its act together? How bad could climate change actually get?</p>
<p>The IPCC report canvassed various scenarios, from the most terrifying to the best possible case. It’s <a href="https://www.nature.com/articles/d41586-020-00177-3">increasingly unlikely</a> Earth will follow the path of very high greenhouse gas emissions, represented in dark red on the graph below, which would very likely lead to global warming of 3.3°C to 5.7°C this century. </p>
<p>But <a href="https://www.nature.com/articles/d41586-020-00177-3">given</a> current policy settings, it’s <a href="https://link.springer.com/article/10.1007%2Fs10584-019-02500-y">plausible</a> Earth will follow a mid-range emissions scenario such as that represented in orange. Such a pathway would lead to global warming of between 2°C and 3.5°C, relative to pre-industrial levels.</p>
<p>So what will Earth look like under warming of that magnitude? And what will life on this planet be like? Academic research can shed light on those crucial questions. And a warning: the answers are confronting.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=830&fit=crop&dpr=1 754w, https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=830&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/416284/original/file-20210816-18-1uiozzb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=830&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>
<h2>An angrier, less hospitable world</h2>
<p>The IPCC report confirmed Earth has warmed 1.09°C since pre-industrial times. This level of warming is already causing significant damage. </p>
<p>Around the world over the past few months, the damage has been strikingly evident. Record-shattering heatwaves have struck <a href="https://theconversation.com/extreme-heat-waves-in-a-warming-world-dont-just-break-records-they-shatter-them-164919">North America’s west</a> and <a href="https://www.bbc.com/news/world-europe-58130893">southern Europe</a>, while extreme rain and flooding has hit <a href="https://www.sciencemag.org/news/2021/07/europe-s-deadly-floods-leave-scientists-stunned">central Europe</a> and <a href="https://www.aljazeera.com/news/2021/8/3/death-toll-in-chinas-henan-floods-triples-to-302-dozens-missing">China</a>. </p>
<p>At 3°C global warming, heatwaves would be even more frequent, intense and longer, while extreme rain will be heavier. The relationship between average global temperature and heat extremes is <a href="https://www.nature.com/articles/s41598-017-12520-2">very strong</a>, although this varies across regions.</p>
<p>Over Australia, heatwaves are expected to be slightly hotter than the corresponding global warming threshold. So with 3°C of global warming, the hottest day of a heatwave will be about 3.6°C warmer than pre-industrial conditions.</p>
<p>What’s more, heatwaves in Australia are projected to become four to five days longer for each degree of global warming. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/climate-change-has-already-hit-australia-unless-we-act-now-a-hotter-drier-and-more-dangerous-future-awaits-ipcc-warns-165396">Climate change has already hit Australia. Unless we act now, a hotter, drier and more dangerous future awaits, IPCC warns</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=634&fit=crop&dpr=1 600w, https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=634&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=634&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=797&fit=crop&dpr=1 754w, https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=797&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/415156/original/file-20210809-17-1lz4fv6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=797&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"><span class="source">IPCC</span></span>
</figcaption>
</figure>
<p>The IPCC findings show in <a href="https://interactive-atlas.ipcc.ch/regional-information#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">some parts of the world</a>, there’s a clear relationship between future increases in global warming and a rise in extreme rainfall events. This includes the eastern part of the United States, Alaska and western Canada, Europe and parts of Russia and Africa. The projected increase applies to both daily rainfall events and those lasting five days.</p>
<p>Explore future projections of extreme rainfall and other climate variables with the IPCC’s <a href="https://interactive-atlas.ipcc.ch/">interactive climate atlas</a>. </p>
<p>Climate change has already damaged the world’s coral reefs. The Great Barrier Reef has bleached three times in the past five years, giving little time for the ecosystem to recover. In a <a href="https://www.ipcc.ch/site/assets/uploads/sites/2/2019/05/SR15_SPM_version_report_LR.pdf">2018 report</a>, the IPCC found coral reefs would decline by a further 70-90% under global warming of 1.5°C. Virtually all reefs would be lost with 2°C warming.</p>
<p>Bushfire risk also increases the more we let the climate warm. As the Australian Academy of Science outlined in a <a href="https://www.science.org.au/supporting-science/science-policy-and-analysis/reports-and-publications/risks-australia-three-degrees-c-warmer-world">report</a> earlier this year, extreme fire days in Australia will increase with global temperatures. </p>
<p>Greater increases are projected for southern and eastern Australia. However, in much of Australia the frequency of extreme fire days increases by 100-300% once 3°C global warming is reached. </p>
<p>And conditions conducive to <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL083699">mega-fires</a> – such as those which occurred during the 2019-20 Black Summer – will occur more often over southeast Australia under continued climate change, especially during late spring. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/seriously-ugly-heres-how-australia-will-look-if-the-world-heats-by-3-c-this-century-157875">Seriously ugly: here's how Australia will look if the world heats by 3°C this century</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="diver swims above bleached coral" src="https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/416247/original/file-20210816-15-1fy5acx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">At 2°C warming, the Great Barrier Reef and others like it will be virtually gone.</span>
<span class="attribution"><span class="source">ARC Centre of Excellence/Tane Sinclair-Taylor</span></span>
</figcaption>
</figure>
<h2>On thin ice</h2>
<p>The more the planet warms, the more we risk triggering disastrous irreversible changes known as “tipping points”. Scientists have identified <a href="https://www.nature.com/articles/d41586-019-03595-0">several potential</a> tipping points which might occur – especially if the climate warms by more than 2°C, in line with the IPCC’s midway scenario.</p>
<p>For example, global warming may cause the West Antarctic ice sheet to collapse, resulting in several metres of sea level rise. The exact extent of global warming required to trigger such changes is <a href="https://www.carbonbrief.org/explainer-nine-tipping-points-that-could-be-triggered-by-climate-change">very uncertain</a>, and climate projections suggest we won’t hit any trigger points <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf">this century</a>.</p>
<p>However, these irreversible changes remain a distinct possibility if greenhouse gas emissions continue their current trajectory.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/rising-seas-and-melting-glaciers-these-changes-are-now-irreversible-but-we-have-to-act-to-slow-them-down-165527">Rising seas and melting glaciers: these changes are now irreversible, but we have to act to slow them down</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="thawed ice along Antarctic shoreline" src="https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=373&fit=crop&dpr=1 600w, https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=373&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=373&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=469&fit=crop&dpr=1 754w, https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=469&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/416257/original/file-20210816-19-105krdt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=469&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ice sheet collapse in Antarctica would trigger irreversible sea level rise.</span>
<span class="attribution"><span class="source">Natacha Pisarenko/AP</span></span>
</figcaption>
</figure>
<h2>The choice is ours</h2>
<p>Some climate changes we’ve described under the midway emissions scenario are awful for society and our environment. </p>
<p>And as CSIRO climate scientist Pep Canadell, a coordinating lead author of a chapter of the IPCC report, <a href="https://www.theguardian.com/australia-news/2021/aug/09/not-too-late-australian-scientists-call-for-urgent-action-to-avoid-the-worst-of-climate-crisis">told</a> the Guardian last week, if greenhouse gas emissions continue unabated “there is no bottom end to how much damage we can create”.</p>
<p>Humanity is now at a crossroads. The IPCC says if we halve global greenhouse gas emissions within the next 15 years, and reach net-zero emissions before 2060, we have a more than 90% chance of keeping <a href="https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf">global warming below 2°C</a>. </p>
<p>That means every action matters. Each fraction of a degree of global warming prevented will reduce the climate damage and increase the chance Earth avoids the most catastrophic impacts of global warming.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ipcc-says-earth-will-reach-temperature-rise-of-about-1-5-in-around-a-decade-but-limiting-any-global-warming-is-what-matters-most-165397">IPCC says Earth will reach temperature rise of about 1.5℃ in around a decade. But limiting any global warming is what matters most</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/166031/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew King receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Nerilie Abram receives funding from the Australian Research Council. She is a member of the international Climate Crisis Advisory Group. </span></em></p><p class="fine-print"><em><span>Sarah Perkins-Kirkpatrick receives funding from the Australian Research Council. She is a Future Fellow, and a chief investigator with the Centre of Excellence for Climate Extremes.</span></em></p>Academic research can shed light on crucial questions about what life on Earth will be like under the most plausible emissions scenarios. And a warning: the answers are confronting.Andrew King, ARC DECRA fellow, The University of MelbourneNerilie Abram, Chief Investigator for the ARC Centre of Excellence for Climate Extremes; Deputy Director for the Australian Centre for Excellence in Antarctic Science, Australian National UniversitySarah Perkins-Kirkpatrick, Chief Investigator on the ARC Centre of Excellence for Climate Extremes; ARC Future Fellow, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1648672021-07-24T12:51:35Z2021-07-24T12:51:35ZNot declaring the Great Barrier Reef as ‘in danger’ only postpones the inevitable<figure><img src="https://images.theconversation.com/files/412841/original/file-20210723-15-az4hmy.jpg?ixlib=rb-1.1.0&rect=0%2C28%2C3822%2C2240&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>After much anticipation, the World Heritage Committee on Friday <a href="https://www.abc.net.au/news/2021-07-23/great-barrier-reef-avoids-in-danger-unesco-tag/100319652">decided against</a> listing the Great Barrier Reef as “in danger”.</p>
<p>The decision ignored the recommendation of the International Union for Conservation of Nature (IUCN) and the UNESCO World Heritage Centre — a recommendation based on analyses by Australian scientific experts of the reef’s declining condition. </p>
<p>In many ways, the outcome from the committee was expected. The Australian government fought very hard against this decision, including lobbying all the committee members, as it has done in previous years. </p>
<p>There was consensus among most of the <a href="https://whc.unesco.org/en/committee/">21 committee members</a> to not apply the in-danger listing at this time. Instead, Australia has been requested to host a joint UNESCO/IUCN monitoring mission to the reef and provide an updated report by February, 2022. </p>
<p>This decision has only postponed the inevitable. It does not change the irrefutable evidence that dangerous impacts are already occurring on the Great Barrier Reef. Some, such as <a href="https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197">coral bleaching</a> and death from <a href="https://apo.org.au/sites/default/files/resource-files/2018-09/apo-nid193206.pdf">marine heatwaves</a>, will continue to accelerate.</p>
<p>The reef currently meets the criteria for in-danger listing. That’s unlikely to improve within the next 12 months. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-barrier-reef-is-not-listed-as-in-danger-but-the-threats-remain-42548">The Barrier Reef is not listed as in danger, but the threats remain</a>
</strong>
</em>
</p>
<hr>
<h2>Political distractions</h2>
<p>Last month, the World Heritage Committee released its <a href="https://whc.unesco.org/archive/2021/whc21-44com-7B.Add-en.pdf">draft decision</a> to list the reef as in-danger, noting the values for which the reef was internationally recognised had declined due to a <a href="https://theconversation.com/the-great-barrier-reef-is-in-trouble-there-are-a-whopping-45-reasons-why-122930">wide range of factors</a>. This includes <a href="https://www.gbrmpa.gov.au/our-work/threats-to-the-reef/declining-water-quality">water pollution</a> and coral bleaching.</p>
<p>The draft decision had expressed concerns that Australia’s progress:</p>
<blockquote>
<p>has been largely insufficient in meeting key targets of the Reef 2050 Plan [and the] deterioration of the ecological processes underpinning the [Reef has] been more rapid and widespread than was previously evident. </p>
</blockquote>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291894/original/file-20190911-190026-1mysner.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A photo depicting two threats to the Great Barrier Reef: coal ships anchored near Abbot Point and a flood plume from the Burdekin River (February 2019); such plumes can carry pollutants and debris to the Great Barrier Reef.</span>
<span class="attribution"><span class="source">Matt Curnock</span></span>
</figcaption>
</figure>
<p>In response, the government <a href="https://www.theguardian.com/environment/2021/jul/19/chinese-unesco-official-defends-plan-to-list-great-barrier-reef-in-danger">claimed it was</a> “blindsided”, and said the UNESCO Secretariat hadn’t followed due process in recommending the decision. It also suggested there had been undue interference from China in making the draft recommendation. </p>
<p>These were political distractions from the real issues. During last night’s debate, one committee member strongly refuted the claims about interference from China and expressed concerns the dialogue had become unnecessarily politicised.</p>
<p>Following the draft decision, the <a href="https://minister.awe.gov.au/ley/media-releases/minister-campaigns-support-great-barrier-reef">intense campaign</a> to reverse the decision began, with environment minister Sussan Ley undertaking a whirlwind visit to numerous countries to meet with ambassadors.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-great-barrier-reef-is-in-trouble-there-are-a-whopping-45-reasons-why-122930">The Great Barrier Reef is in trouble. There are a whopping 45 reasons why</a>
</strong>
</em>
</p>
<hr>
<p>The government even <a href="https://www.theguardian.com/environment/2021/jul/14/australia-to-fly-ambassadors-to-great-barrier-reef-ahead-of-in-danger-list-vote#:%7E:text=The%20government's%20official%20reef%20ambassador,upcoming%20world%20heritage%20committee%20meeting.">hosted international ambassadors</a> from 13 countries and the EU, taking them on a snorkelling trip. And it reported an increase in coral cover over the past two years as good news, ignoring the fact the <a href="https://www.aims.gov.au/reef-monitoring/gbr-condition-summary-2020-2021">assessment</a> had cautioned the recovery was driven by weedy coral species most vulnerable to future climate impacts.</p>
<p>This wasn’t the first time Australia has undertaken significant levels of diplomatic lobbying of World Heritage Committee members to gain support for its position. </p>
<p>In 1999, Australia also strongly opposed the recommended in-danger <a href="https://whc.unesco.org/en/decisions/5722/">listing of Kakadu National Park</a>, following the Jabiluka mine proposal. This led to an extraordinary meeting of the committee being convened in Paris, specifically to discuss this matter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Turtle" src="https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412845/original/file-20210723-13-14khpgf.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">Australia is expected to hand in an updated report on the reef in February 2022.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>More focus on climate change</h2>
<p>During its current meeting, the World Heritage Committee approved the <a href="https://whc.unesco.org/archive/2021/whc21-44com-7C-en.pdf">draft UNESCO Climate Action Policy</a>, which will guide the protection and conservation of World Heritage sites.</p>
<p>This policy will be ratified at the UN General Assembly later this year, but the fact it’s still a draft was one of several excuses the Australian government made as to why the reef should not be “<a href="https://www.theaustralian.com.au/subscribe/news/1/?sourceCode=TAWEB_WRE170_a&dest=https%3A%2F%2Fwww.theaustralian.com.au%2Fcommentary%2Faustralia-shouldnt-be-poster-boy-for-climate-change-perils%2Fnews-story%2Fdd4d6ae08358bbd6133ebb609f5be549&memtype=anonymous&mode=premium">singled out</a>”. </p>
<p>The reef is one of the most iconic marine protected areas on the planet. Given Australia continues to have one of the highest per capita emission rates in the world, and has more capacity to address climate change than most other countries, <a href="https://theconversation.com/is-australia-really-doing-enough-for-the-great-barrier-reef-why-criticisms-of-unescos-in-danger-recommendation-dont-stack-up-163641">it makes sense</a> for the spotlight to be on Australia’s actions. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial photo of part of the reef" src="https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412844/original/file-20210723-17-1swqtpf.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">Marine heatwaves and water pollution are major threats to the Great Barrier Reef.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Not surprisingly, climate change was the central issue during the committee’s debate last night. UNESCO is now more focused on climate change than ever before, recognising the “window of opportunity to act” is now.</p>
<p>The delegates broadly agreed climate change remains the most serious threat, not just to the Great Barrier Reef but also to many other iconic World Heritage properties. Venice, for example, also dodged a <a href="https://www.washingtonpost.com/world/venice-risks-move-to-unesco-world-heritage-site-in-danger/2021/07/22/69d9b3f2-eaf2-11eb-a2ba-3be31d349258_story.html">potential in-danger listing</a> at this meeting.</p>
<p>Rather than making challenging decisions now, it’s clear the committee is simply kicking the can down the road. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1418525715041898499"}"></div></p>
<p>Some committee members remarked during the meeting about the need to “maintain the credibility of the Convention” and acknowledged that the world is watching. The spotlight on the reef, and on Australia, will only intensify in coming years.</p>
<p>The government’s <a href="https://www.gbrmpa.gov.au/our-work/outlook-report-2019">own report</a> from 2019 shows many of the values for which the reef was inscribed on the World Heritage list in 1981 have declined in recent decades. Yet every delay weakens Australia’s claim it is doing all it can to protect the reef. </p>
<p>Later this year, the next <a href="https://ukcop26.org/">major international climate summit</a> will be held in Glasgow, Scotland, where even more attention will be placed on Australia’s inadequate actions. </p>
<h2>An in-danger listing is not a punishment</h2>
<p>It’s important to remember that throughout the meeting, UNESCO and the committee made it clear an in-danger listing is not a sanction or punishment. Rather, it’s a call to the international community that a World Heritage property is under threat, thereby triggering actions to protect it for future generations.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-australia-really-doing-enough-for-the-great-barrier-reef-why-criticisms-of-unescos-in-danger-recommendation-dont-stack-up-163641">Is Australia really doing enough for the Great Barrier Reef? Why criticisms of UNESCO’s 'in danger' recommendation don’t stack up</a>
</strong>
</em>
</p>
<hr>
<p>Now, more than ever, it is important to expand efforts to reduce the locally manageable impacts, such as poor water quality, while rapidly accelerating action on climate change. </p>
<p>These efforts must occur locally, nationally and globally. Reducing greenhouse gas emissions is critical to stop the worst of the impacts now unfolding, not just on the reef, but on all the world’s natural and cultural heritage.</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><em>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.</em></p>
<hr><img src="https://counter.theconversation.com/content/164867/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jon Day previously worked for the Great Barrier Reef Marine Park Authority between 1986 and 2014, and was one of the Directors at GBRMPA between 1998 and 2014. He represented Australia as one of the formal delegates to the World Heritage Committee between 2007-2011.</span></em></p><p class="fine-print"><em><span>Scott Heron receives funding from Australian Research Council and NASA ROSES Ecological Forecasting.</span></em></p><p class="fine-print"><em><span>Terry Hughes 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>Friday’s decision from the World Heritage Committee doesn’t change the irrefutable evidence that dangerous impacts are occurring on the Great Barrier Reef.Jon C. Day, PSM, Adjunct Senior Research Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook UniversityScott F. Heron, Associate Professor, James Cook UniversityTerry Hughes, Distinguished Professor, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1643182021-07-15T19:26:22Z2021-07-15T19:26:22ZWhen coral dies, tiny invertebrates boom. This could dramatically change the food web on the Great Barrier Reef<figure><img src="https://images.theconversation.com/files/411368/original/file-20210715-25-rw27zj.jpg?ixlib=rb-1.1.0&rect=28%2C22%2C3805%2C2132&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>This week, international ambassadors will <a href="https://www.theguardian.com/environment/2021/jul/14/australia-to-fly-ambassadors-to-great-barrier-reef-ahead-of-in-danger-list-vote">take a snorkelling trip</a> to the Great Barrier Reef as part of the Australian government’s efforts to stop the reef getting on the <a href="https://theconversation.com/australian-government-was-blindsided-by-un-recommendation-to-list-great-barrier-reef-as-in-danger-but-its-no-great-surprise-163159">world heritage</a> “in danger” list.</p>
<p>The <a href="https://whc.unesco.org/en/list/154/">World Heritage Centre</a> of UNESCO is set to make its final decision on whether to officially brand the reef as “in danger” later this month. </p>
<p>To many coral reef researchers like myself, who have witnessed firsthand the increasing <a href="https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197">coral bleaching</a> and <a href="https://doi.org/10.1111/gcb.13593">cyclone-driven destruction</a> of this global icon, an in-danger listing comes as no surprise. </p>
<p>But the implications of mass coral death are complex — just because coral is dying doesn’t mean marine life there will end. Instead, it will change. </p>
<p>In <a href="https://doi.org/10.1007/s00227-021-03911-1">recent research</a>, my colleagues and I discovered dead coral hosted 100 times more microscopic invertebrates than healthy coral. This means up to 100 times more fish food is available on reefs dominated by dead coral compared with live, healthy coral.</p>
<p>This is a near-invisible consequence of coral death, with dramatic implications for reef food webs. </p>
<h2>When coral dies</h2>
<p>Tiny, mobile invertebrates — between 0.125 and 4 millimetres in size — are <a href="https://doi.org/10.3354/meps13295">ubiquitous inhabitants</a> of the surfaces of all reef structures and are the main <a href="https://doi.org/10.1007/s00338-017-1588-3">food source</a> for approximately <a href="https://doi.org/10.1007/s00227-015-2710-0">70% of fish species</a> on the Great Barrier Reef. </p>
<p>These invertebrates, most visible only under a microscope, are commonly known as “epifauna” and include species of crustaceans, molluscs, and polychaete worms.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/australian-government-was-blindsided-by-un-recommendation-to-list-great-barrier-reef-as-in-danger-but-its-no-great-surprise-163159">Australian government was 'blindsided' by UN recommendation to list Great Barrier Reef as in-danger. But it's no great surprise</a>
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<p>When corals die, their skeletons are quickly overgrown by fine, thread-like “<a href="https://doi.org/10.3354/meps10513">turfing algae</a>”. Turf-covered coral skeletons then break down into beds of rubble. </p>
<p>We wanted to find out how the tiny epifaunal invertebrates — upon which many fish depend - might respond to the widespread replacement of live healthy coral with dead, turf-covered coral. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=601&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=601&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=601&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410982/original/file-20210713-19-tnqt2o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A sample of epifauna under the microscope.</span>
<span class="attribution"><span class="source">Kate Fraser</span></span>
</figcaption>
</figure>
<p>I took my SCUBA gear and a box of lab equipment, and dived into a series of reefs across eastern Australia, from the Solitary Islands in New South Wales to Lizard Island on the northern Great Barrier Reef. </p>
<p>Underwater, I carefully gathered into sandwich bags the tiny invertebrates living on various species of live coral and those living on dead, turf-covered coral. </p>
<p>But things really got interesting back in the laboratory under the microscope. I sorted each sandwich bag sample of epifauna into sizes, identified them as best I could (many, if not most, species remain <a href="https://doi.org/10.1046/j.1439-0485.2001.01726.x">unknown</a> to science), and counted them. </p>
<p>I quickly noticed samples taken from live coral took just minutes to count, whereas samples from dead coral could take hours. There were exponentially more animals in the dead coral samples.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411140/original/file-20210714-13-1bf7ccv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The Great Barrier Reef may soon be listed as ‘in danger’</span>
<span class="attribution"><span class="source">Rick Stuart-Smith</span></span>
</figcaption>
</figure>
<h2>Why do they prefer dead coral?</h2>
<p>Counting individual invertebrates is only so useful when considering their contribution to the food web. So we instead used the much more useful metric of “productivity”, which looks at how much weight (biomass) of organisms is produced daily for a given area of reef.</p>
<p>We found epifaunal productivity was far greater on dead, turf-covered coral. The main contributors were the tiniest epifauna — thousands of harpacticoid copepods (a type of crustacean) an eighth of a millimetre in size. </p>
<p>In contrast, coral crabs and glass shrimp contributed the most productivity to epifaunal communities on live coral. At one millimetre and larger, these animals are relative giants in the epifaunal world, with fewer than ten individuals in most live coral samples.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411136/original/file-20210714-17-1b3hhql.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">Dead coral rubble overgrown with turfing algae.</span>
<span class="attribution"><span class="source">Rick Stuart-Smith</span></span>
</figcaption>
</figure>
<p>These striking differences may be explained by two things. </p>
<p>First: <a href="https://doi.org/10.1016/j.cub.2014.03.026">shelter</a>. Live coral may look complex to the naked eye, but if you zoom in you’ll find turfing algae has more structural complexity that tiny epifauna can hide in, protecting them from predators.</p>
<p>A coral head is actually a community of individual coral polyps, each with a tiny mouth and fine tentacles to <a href="https://doi.org/10.1111/j.1469-185X.2008.00058.x">trap prey</a>. To smaller epifauna, such as harpacticoid copepods, the surface of live coral is a wall of mouths and a very undesirable habitat.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/almost-60-coral-species-around-lizard-island-are-missing-and-a-great-barrier-reef-extinction-crisis-could-be-next-163714">Almost 60 coral species around Lizard Island are 'missing' – and a Great Barrier Reef extinction crisis could be next</a>
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<p>Second: food. Many epifauna, regardless of size, are <a href="https://link.springer.com/content/pdf/10.1007/BF00649514.pdf">herbivores</a> (plant-eaters) or <a href="https://doi.org/10.1002/rcm.7443">detritivores</a> (organic waste-eaters). Turfing algae is a brilliant <a href="https://doi.org/10.1111/j.1461-0248.2012.01804.x">trap</a> for fine detritus and an excellent substrate for growing films of even smaller microscopic algae. </p>
<p>This means dead coral overgrown by turfing algae represents a smorgasbord of food options for the tiniest epifauna through to the largest.</p>
<p>Meanwhile, many larger epifauna like coral crabs have evolved to live exclusively on live coral, eating the <a href="https://doi.org/10.1007/s00338-011-0748-0">mucus</a> that covers the polyps or particles trapped by the polyps themselves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411371/original/file-20210715-27-u534ne.jpeg?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">Harpacticoid copepod are just an eighth of a millimetre in size.</span>
<span class="attribution"><span class="source">Naukhan/Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What this means for life on the reef?</h2>
<p>As corals reefs continue to decline, we can expect increased productivity at the base level of reef food webs, with a shift from larger crabs and shrimp to small harpacticoid copepods. </p>
<p>This will affect the flow of food and energy throughout reef food webs, markedly changing the structure of fish and other animal communities. The abundance of animals that eat invertebrates will likely <a href="https://doi.org/10.1038/s41586-018-0359-9">boom</a> with increased coral death. </p>
<p>We might expect higher numbers of fish such as <a href="https://doi.org/10.1007/s00227-015-2710-0">wrasses</a>, <a href="https://fishesofaustralia.net.au/home/family/22">cardinalfish</a>, <a href="https://fishesofaustralia.net.au/home/family/135">triggerfish</a>, and <a href="https://fishesofaustralia.net.au/home/family/344">dragonets</a>, with species preferring the smallest epifauna most likely to flourish.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411137/original/file-20210714-13-1894lqw.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 dragonet species, mandarinfish, feeds on the smallest harpacticoid copepod prey.</span>
<span class="attribution"><span class="source">Rick Stuart-Smith</span></span>
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</figure>
<p>Invertebrate-eating animals are food for a diversity of carnivores on a coral reef, and most fish Australians want to eat are <a href="https://doi.org/10.1371/journal.pone.0140270">carnivores</a>, such as coral trout, snapper, and Spanish mackerel.</p>
<p>While we didn’t investigate exactly which species are likely to increase following widespread coral death, it’s safe to say populations of fish targeted by recreational and commercial fisheries on Australia’s coral reefs are likely to change as live coral is lost, some for better and some for worse.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-outlook-for-coral-reefs-remains-grim-unless-we-cut-emissions-fast-new-research-160251">The outlook for coral reefs remains grim unless we cut emissions fast — new research</a>
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<p>The Great Barrier Reef is undoubtedly in danger, and it’s important that we make every effort to protect and conserve the remaining live, healthy coral. However, if corals continue to die, there will remain an abundance of life in their absence, albeit very different life from that to which we are accustomed. </p>
<p>As long as there is hard structure for algae to grow on, there will be epifauna. And where there is epifauna, there is food for fish, although perhaps not for all the fish we want to eat.</p><img src="https://counter.theconversation.com/content/164318/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Fraser did not receive funding for the research but worked under grants received by her colleagues from the Australian Research Council</span></em></p>Just because coral is dying, doesn’t mean marine life in reefs will end. New research found dead coral hosted 100 times more microscopic invertebrates than healthy coral.Kate Fraser, Marine Ecologist, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.