Snorkellers discover rare, giant 400-year-old coral – one of the oldest on the Great Barrier Reef


Richard Woodgett

Adam Smith, James Cook University; Nathan Cook, James Cook University, and Vicki Saylor, Indigenous KnowledgeSnorkellers on the Great Barrier Reef have discovered a huge coral more than 400 years old which is thought to have survived 80 major cyclones, numerous coral bleaching events and centuries of exposure to other threats. We describe the discovery in research published today.

Our team surveyed the hemispherical structure, which comprises small marine animals and calcium carbonate, and found it’s the Great Barrier Reef’s widest coral, and one of the oldest.

It was discovered off the coast of Goolboodi (Orpheus Island), part of Queensland’s Palm Island Group. Traditional custodians of the region, the Manbarra people, have called the structure Muga dhambi, meaning “big coral”.

For now, Muga dhambi is in relatively good health. But climate change, declining water quality and other threats are taking a toll on the Great Barrier Reef. Scientists, Traditional Owners and others must keep a close eye on this remarkable, resilient structure to ensure it is preserved for future generations.

coral and snorkellers
Muga dhambi is the widest coral structure recorded on the Great Barrier Reef.
Richard Woodgett

Far older than European settlement

Muga dhambi is located in a relatively remote, rarely visited and highly protected marine area. It was found during citizen science research in March this year, on a reef slope not far from shore.

We conducted a literature review and consulted other scientists to compare the size, age and health of the structure with others in the Great Barrier Reef and internationally.

We measured the structure at 5.3 metres tall and 10.4 metres wide. This makes it 2.4 metres wider than the widest Great Barrier Reef coral previously measured by scientists.

Muga dhambi is of the coral genus Porites and is one of a large group of corals known as “massive Porites”. It’s brown to cream in colour and made of small, stony polyps.

These polyps secrete layers of calcium carbonate beneath their bodies as they grow, forming the foundations upon which reefs are built.

Muga dhambi’s height suggests it is aged between 421 and 438 years old – far pre-dating European exploration and settlement of Australia. We made this calculation based on rock coral growth rates and annual sea surface temperatures.

The Australian Institute of Marine Science has investigated more than 328 colonies of massive Porites corals along the Great Barrier Reef and has aged the oldest at 436 years. The institute has not investigated the age of Muga dhambi, however the structure is probably one of the oldest on the Great Barrier Reef.

Other comparatively large massive Porites have previously been found throughout the Pacific. One exceptionally large colony in American Samoa measured 17m × 12m. Large Porites have also been found near Taiwan and Japan.

Mountainous island and blue sea
Muga dhambi was discovered in waters off Goolboodi (Orpheus Island).
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Resilient, but under threat

We reviewed environmental events over the past 450 years and found Muga dhambi is unusually resilient. It has survived up to 80 major cyclones, numerous coral bleaching events and centuries of exposure to invasive species, low tides and human activity.

About 70% of Muga dhambi consisted of live coral, but the remaining 30% was dead. This section, at the top of the structure, was covered with green boring sponge, turf algae and green algae.

Coral tissue can die from exposure to sun at low tides or warm water. Dead coral can be quickly colonised by opportunistic, fast growing organisms, as is the case with Muga dhambi.

Green boring sponge invades and excavates corals. The sponge’s advances will likely continue to compromise the structure’s size and health.

We found marine debris at the base of Muga dhambi, comprising rope and three concrete blocks. Such debris is a threat to the marine environment and species such as corals.

We found no evidence of disease or coral bleaching.




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to come
The structure may be compromised by the advance of a sponge species across Muga dhambi (sponge is the darker half in this image).
Richard Woodgett

‘Old man’ of the sea

A Traditional Owner from outside the region took part in our citizen science training which included surveys of corals, invertebrates and fish. We also consulted the Manbarra Traditional Owners about and an appropriate cultural name for the structure.

Before recommending Muga dhambi, the names the Traditional Owners considered included:

  • Muga (big)
  • Wanga (home)
  • Muugar (coral reef)
  • Dhambi (coral)
  • Anki/Gurgu (old)
  • Gulula (old man)
  • Gurgurbu (old person).

Indigenous languages are an integral part of Indigenous culture, spirituality, and connection to country. Traditional Owners suggested calling the structure Muga dhambi would communicate traditional knowledge, language and culture to other Indigenous people, tourists, scientists and students.




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coral rock under water with sky
It’s hoped the name Muga dhambi will encourage recognition of the connection Indigenous people have to the coral structure.
Richard Woodgett

A wonder for all generations

No database exists for significant corals in Australia or globally. Cataloguing the location of massive and long-lived corals can be benefits.

For example from a scientific perspective, it can allow analyses which can help understand century-scale changes in ocean events and can be used to verify climate models. Social and economic benefits can include diving tourism and citizen science, as well as engaging with Indigenous culture and stewardship.

However, cataloguing the location of massive corals could lead to them being damaged by anchoring, research and pollution from visiting boats.

Looking to the future, there is real concern for all corals in the Great Barrier Reef due to threats such as climate change, declining water quality, overfishing and coastal development. We recommend monitoring of Muga dhambi in case restoration is needed in future.

We hope our research will mean current and future generations care for this wonder of nature, and respect the connections of Manbarra Traditional Owners to their Sea Country.




Read more:
Not declaring the Great Barrier Reef as ‘in danger’ only postpones the inevitable


The Conversation


Adam Smith, Adjunct Associate Professor, James Cook University; Nathan Cook, Marine Scientist , James Cook University, and Vicki Saylor, Manbarra Traditional Owner, Indigenous Knowledge

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Coral, meet coral: how selective breeding may help the world’s reefs survive ocean heating


Anna Scott, Author provided

Emily Howells, Southern Cross University and David Abrego, Southern Cross UniversityA single generation of selective breeding can make corals better able to withstand extreme temperatures, according to our new research. The discovery could offer a lifeline to reefs threatened by the warming of the world’s oceans.

Our research, published in Science Advances, shows corals from some of the world’s hottest seas can transfer beneficial genes associated with heat tolerance to their offspring, even when crossbred with corals that have never experienced such temperatures.

Across the world, corals vary widely, both in the temperatures they experience and their ability to withstand high temperatures without becoming stressed or dying. In the Persian Gulf, corals have genetically adapted to extreme water temperatures, tolerating summer conditions above 34℃ for weeks at a time, and withstanding daily averages up to 36℃.

These water temperatures are 2-4℃ higher than any other region where corals grow, and are on a par with end-of-century projections for reefs outside the Persian Gulf.

This led us to ask whether beneficial gene variants could be transferred to coral populations that are naïve to these temperature extremes. To find out, we collected fragments of Platygyra daedalea corals from the Persian Gulf, and cross-bred them with corals of the same species from the Indian Ocean, where summer temperatures are much cooler.

Platygyra coral colony
Platygyra, a brain-shaped coral found in many parts of the world.
Emily Howells, Author provided

We then heat-stressed the resulting offspring (more than 12,000 individual coral larvae) to see whether they could withstand temperatures of 33°C and 36°C — the summer maximums of their parents’ respective locations.

Immediate gains

We found an immediate transfer of heat tolerance when Indian Ocean mothers were crossed with Persian Gulf fathers. These corals showed an 84% increase in survival at high temperatures relative to purebred Indian Ocean corals, making them similarly resilient to purebred Persian Gulf corals.

Genome sequencing confirmed that gains in heat tolerance were due to the inheritance of beneficial gene variants from the Persian Gulf corals. Most Persian Gulf fathers produced offspring that were better able to withstand heat stress, and these fathers and their offspring had crucial variants associated with better heat tolerance.

Conversely, most Indian Ocean fathers produced offspring that were less able to survive heat stress, and were less likely to have gene variants associated with heat tolerance.




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Survival of the fittest

Encouragingly, gene variants associated with heat tolerance were not exclusive to Persian Gulf corals. Two fathers from the Indian Ocean produced offspring with unexpectedly high survival under heat stress, and had some of the same tolerance-associated gene variants that are prevalent in Persian Gulf corals.

This suggests that some populations have genetic variation upon which natural selection can act as the world’s oceans grow hotter. Selective breeding might be able to accelerate this process.




Read more:
Heat-tolerant corals can create nurseries that are resistant to bleaching


We are now assessing the genetic basis for heat tolerance in the same species of coral on the Great Barrier Reef and in Western Australia. We want to find out what gene variants are associated with heat tolerance, how these variants are distributed within and among reefs, and whether they are the same as those that allow corals in the Persian Gulf to survive such extreme temperatures.

This knowledge will help us understand the potential for Australian corals to adapt to rapid warming.

Although our study shows selective breeding can significantly improve the resilience of corals to ocean warming, we don’t yet know whether there are any trade-offs between thermal tolerance and other important traits, and whether there are significant genetic risks involved in such breeding.

Platygyra larvae
Platygyra larvae. It remains to be seen whether the genetic benefits of heat-tolerance genes persist throughout life.
Emily Howells, Author provided

Our study was done on coral larvae without the algae that live in close harmony with corals after they settle on reefs. So it will also be important to examine whether the genetic improvements to heat tolerance continue into the corals’ later life stages, when they team up with these algae.

Of course, saving corals from the perils of ocean warming will require action on multiple fronts — there is no silver bullet. Selective breeding might provide some respite to particular coral populations, but it won’t be enough to protect entire ecosystems, and nor is it a substitute for the urgent reduction of greenhouse emissions needed to limit the oceans’ warming.The Conversation

Emily Howells, Senior Research Fellow in Marine Biology, Southern Cross University and David Abrego, Lecturer, National Marine Science Centre, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Not declaring the Great Barrier Reef as ‘in danger’ only postpones the inevitable


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Jon C. Day, James Cook University; Scott F. Heron, James Cook University, and Terry Hughes, James Cook UniversityAfter much anticipation, the World Heritage Committee on Friday decided against listing the Great Barrier Reef as “in danger”.

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.

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.

There was consensus among most of the 21 committee members 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.

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 coral bleaching and death from marine heatwaves, will continue to accelerate.

The reef currently meets the criteria for in-danger listing. That’s unlikely to improve within the next 12 months.




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The Barrier Reef is not listed as in danger, but the threats remain


Political distractions

Last month, the World Heritage Committee released its draft decision to list the reef as in-danger, noting the values for which the reef was internationally recognised had declined due to a wide range of factors. This includes water pollution and coral bleaching.

The draft decision had expressed concerns that Australia’s progress:

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.

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.
Matt Curnock

In response, the government claimed it was “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.

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.

Following the draft decision, the intense campaign to reverse the decision began, with environment minister Sussan Ley undertaking a whirlwind visit to numerous countries to meet with ambassadors.




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The government even hosted international ambassadors 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 assessment had cautioned the recovery was driven by weedy coral species most vulnerable to future climate impacts.

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.

In 1999, Australia also strongly opposed the recommended in-danger listing of Kakadu National Park, following the Jabiluka mine proposal. This led to an extraordinary meeting of the committee being convened in Paris, specifically to discuss this matter.

Turtle
Australia is expected to hand in an updated report on the reef in February 2022.
Shutterstock

More focus on climate change

During its current meeting, the World Heritage Committee approved the draft UNESCO Climate Action Policy, which will guide the protection and conservation of World Heritage sites.

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 “singled out”.

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, it makes sense for the spotlight to be on Australia’s actions.

Aerial photo of part of the reef
Marine heatwaves and water pollution are major threats to the Great Barrier Reef.
Shutterstock

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.

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 potential in-danger listing at this meeting.

Rather than making challenging decisions now, it’s clear the committee is simply kicking the can down the road.

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.

The government’s own report 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.

Later this year, the next major international climate summit will be held in Glasgow, Scotland, where even more attention will be placed on Australia’s inadequate actions.

An in-danger listing is not a punishment

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.




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Is Australia really doing enough for the Great Barrier Reef? Why criticisms of UNESCO’s ‘in danger’ recommendation don’t stack up


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.

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.


This story is part of Oceans 21

Our series on the global ocean opened with five in-depth profiles. 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.The Conversation


Jon C. Day, PSM, Adjunct Senior Research Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook University; Scott F. Heron, Associate Professor, James Cook University, and Terry Hughes, Distinguished Professor, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

When coral dies, tiny invertebrates boom. This could dramatically change the food web on the Great Barrier Reef


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Kate Fraser, University of TasmaniaThis week, international ambassadors will take a snorkelling trip to the Great Barrier Reef as part of the Australian government’s efforts to stop the reef getting on the world heritage “in danger” list.

The World Heritage Centre of UNESCO is set to make its final decision on whether to officially brand the reef as “in danger” later this month.

To many coral reef researchers like myself, who have witnessed firsthand the increasing coral bleaching and cyclone-driven destruction of this global icon, an in-danger listing comes as no surprise.

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.

In recent research, 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.

This is a near-invisible consequence of coral death, with dramatic implications for reef food webs.

When coral dies

Tiny, mobile invertebrates — between 0.125 and 4 millimetres in size — are ubiquitous inhabitants of the surfaces of all reef structures and are the main food source for approximately 70% of fish species on the Great Barrier Reef.

These invertebrates, most visible only under a microscope, are commonly known as “epifauna” and include species of crustaceans, molluscs, and polychaete worms.




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When corals die, their skeletons are quickly overgrown by fine, thread-like “turfing algae”. Turf-covered coral skeletons then break down into beds of rubble.

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.

A sample of epifauna under the microscope.
Kate Fraser

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.

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.

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 unknown to science), and counted them.

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.

The Great Barrier Reef may soon be listed as ‘in danger’
Rick Stuart-Smith

Why do they prefer dead coral?

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.

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.

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.

Dead coral rubble overgrown with turfing algae.
Rick Stuart-Smith

These striking differences may be explained by two things.

First: shelter. 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.

A coral head is actually a community of individual coral polyps, each with a tiny mouth and fine tentacles to trap prey. To smaller epifauna, such as harpacticoid copepods, the surface of live coral is a wall of mouths and a very undesirable habitat.




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Second: food. Many epifauna, regardless of size, are herbivores (plant-eaters) or detritivores (organic waste-eaters). Turfing algae is a brilliant trap for fine detritus and an excellent substrate for growing films of even smaller microscopic algae.

This means dead coral overgrown by turfing algae represents a smorgasbord of food options for the tiniest epifauna through to the largest.

Meanwhile, many larger epifauna like coral crabs have evolved to live exclusively on live coral, eating the mucus that covers the polyps or particles trapped by the polyps themselves.

Harpacticoid copepod are just an eighth of a millimetre in size.
Naukhan/Wikimedia, CC BY

What this means for life on the reef?

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.

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 boom with increased coral death.

We might expect higher numbers of fish such as wrasses, cardinalfish, triggerfish, and dragonets, with species preferring the smallest epifauna most likely to flourish.

The dragonet species, mandarinfish, feeds on the smallest harpacticoid copepod prey.
Rick Stuart-Smith

Invertebrate-eating animals are food for a diversity of carnivores on a coral reef, and most fish Australians want to eat are carnivores, such as coral trout, snapper, and Spanish mackerel.

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.




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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.

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.The Conversation

Kate Fraser, Marine Ecologist, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Almost 60 coral species around Lizard Island are ‘missing’ – and a Great Barrier Reef extinction crisis could be next


Michael Emslie

Zoe Richards, Curtin UniversityThe federal government has opposed a recommendation by a United Nations body that the Great Barrier Reef be listed as “in danger”. But there’s no doubt the natural wonder is in dire trouble. In new research, my colleagues and I provide fresh insight into the plight of many coral species.

Worsening climate change, and subsequent marine heatwaves, have led to mass coral deaths on tropical reefs. However, there are few estimates of how reduced overall coral cover is linked to declines in particular coral species.

Our research examined 44 years of coral distribution records around Lizard Island, at the northern end of the Great Barrier Reef. We found 16% of coral species have not been seen for many years and are at risk of either local extinction, or disappearing from parts of their local range.

This is alarming, because local extinctions often signal wider regional – and ultimately global – species extinction events.

Healthy coral near Lizard Island in 2011, top, then six years later after two bleaching events, bottom.
Healthy coral near Lizard Island in 2011, top, then six years later after two bleaching events, bottom.
Zoe Richards

Sobering findings

The Lizard Island reef system is 270 kilometres north of Cairns. It has suffered major disturbances over the past four decades: repeated outbreaks of crown-of-thorns seastars, category 4 cyclones in 2014 and 2015, and coral bleaching events in 2016, 2017 and 2020.

Our research focused on “hermatypic” corals around Lizard Island. These corals deposit calcium carbonate and form the hard framework of the reef.

We undertook hard coral biodiversity surveys four times between 2011 and 2020, across 14 sites. We combined the results with published and photographic species records from 1976 to 2020.

red fleshy coral with blue spots
Micromussa lordhowensis is popular in the aquarium trade.
Zoe Richards

Of 368 hard coral species recorded around Lizard Island, 28 (7.6%) have not been reliably recorded since before 2011 and may be at risk of local extinction. A further 31 species (8.4%) have not been recorded since 2015 and may be at risk of range reduction (disappearance from parts of its local range).

The “missing” coral species include:

  • Acropora abrotanoides, a robust branching shallow water coral that lives on the reef crest and reef flat has not been since since 2009
  • Micromussa lordhowensis, a low-growing coral with colourful fleshy polyps. Popular in the aquarium trade, it often grows on reef slopes but has not been seen since 2005
  • Acropora aspera, a branching coral which prefers very shallow water and has been recorded just once, at a single site, since 2011.

The finding that 59 coral species are at risk of local extinction or range reduction is significant. Local range reductions are often precursors to local species extinctions. And local species extinctions are often precursors to regional, and ultimately global, extinction events.

Each coral species on the reef has numerous vital functions. It might provide habitat or food to other reef species, or biochemicals which may benefit human health. One thing is clear: every coral species matters.




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reddish coral underwater
Acropa abrotanoides, one of the corals ‘missing’ from around Lizard Island.
Zoe Richards

A broader extinction crisis?

As human impacts and climate threats mount, there is growing concern about the resilience of coral biodiversity. Our research suggests such concerns are well-founded at Lizard Island.

Coral reef communities are dynamic, and so detecting species loss can be difficult. Our research found around Lizard Island, the diversity of coral species fluctuated over the past decade. Significant declines were recorded from 2011 to 2017, but diversity recovered somewhat in the three following years.

Local extinctions often happen incrementally and can therefore be “invisible”. To detect them, and to account for natural variability in coral communities, long-term biodiversity monitoring across multiple locations and time frames is needed.

Green coral
Acropora aspera has been recorded just once, at a single location, since 2011.
Anne Hoggett

In most locations however, data on the distribution and abundance of all coral species in a community is lacking. This means it can be hard to assess changes, and to understand the damage that climate change and other human-caused stressors are having on each species.

Only with this extra information can scientists conclusively say if the level of local extinction risk at Lizard Island indicates a risk that coral species may become extinct elsewhere – across the Great Barrier Reef and beyond.




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Is Australia really doing enough for the Great Barrier Reef? Why criticisms of UNESCO’s ‘in danger’ recommendation don’t stack up


The Conversation


Zoe Richards, Senior Research Fellow, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Is Australia really doing enough for the Great Barrier Reef? Why criticisms of UNESCO’s ‘in danger’ recommendation don’t stack up


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Terry Hughes, James Cook University; Jon C. Day, James Cook University, and Ove Hoegh-Guldberg, The University of QueenslandIn case you missed it, last week the World Heritage Centre of UNESCO revealed its draft decision to list the Great Barrier Reef as “in danger” — a decision that appeared to shock the Australian government.

In an opinion piece published yesterday in The Australian newspaper, Environment Minister Sussan Ley acknowledged climate change is the biggest threat to the Great Barrier Reef, and that it “has been through a few rough years”.

She has also suggested, however, UNESCO’s draft in-danger decision is a surprise and was politically motivated. Neither of these claims is credible.

So let’s look at Australia’s reaction so far, and why criticisms of UNESCO’s draft decision don’t stack up.

The poster child for climate change

An in-danger listing of a World Heritage property recognises a decline in the “outstanding universal value” that makes the site internationally significant. It sets off alarm bells to identify the underlying causes of decline, and triggers stronger interventions to prevent further damage.

Ley foresees a negative effect of the proposed in-danger listing on reef tourism. However, there’s no evidence from the Galapagos Islands, the Belize Barrier Reef or the Everglades National Park — all World Heritage properties and tourism hotspots — that an in-danger listing led to any discernible impacts on tourist numbers.

Most tourists, international or domestic, are already well aware of the pressures facing the Great Barrier Reef, but they are still keen to see it. From 2015–2018, more than two million visitors each year used a tourism operator to visit the reef. During 2020, COVID led to significant decline in visitor numbers so this period has been particularly difficult for the tourism industry.

Ley also claimed Australia, and the reef, didn’t deserve to be the poster child for climate change perils. But why can’t they be? The Great Barrier Reef is one of the most obvious examples of the costs of inaction on anthropogenic climate change.

The Great Barrier Reef was inscribed as a World Heritage Area in 1981. And for the past two decades Australia has meticulously documented its ongoing deterioration.

According to Australia’s regular reporting to UNESCO, the major causes of the reef’s decline in outstanding universal value is pollution from agricultural runoff, which has now been eclipsed by heat stress from climate change.




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Extreme summer temperatures in 1998, 2002, 2016, 2017 and 2020 have reduced coral cover and changed the mix of species, altering the biodiversity and other World Heritage attributes of the reef for many decades to come.

Unless global warming is stabilised soon, the reef will become unrecognisable. Indeed, in 2019, Australia’s latest five-yearly Great Barrier Reef Outlook Report projected the future of the reef as “very poor”.

Is Australia doing enough?

Ley also suggests Australia is doing everything it can to protect the reef — but is it really?

UNESCO certainty doesn’t think so. The draft decision from UNESCO, which will be considered next month by the World Heritage Committee, noted that interventions to reduce inshore pollution over the past five years have been “largely deficient”.

Bleached coral
There has been slow progress in meeting reef water quality targets.
Shutterstock

There have been some positive achievements in reducing water pollution levels. But the slow progress in meeting many of the water quality targets is documented clearly in the 2017–2018 and 2019 reef Water Quality Report Cards, produced jointly by the federal and Queensland governments.

UNESCO cites Australia’s poor progress on reducing emissions as an additional area requiring considerable improvement, to meet the objectives of the Paris Agreement and Australia’s responsibilities under the World Heritage Convention.




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UNESCO has also asked Australia to work with it to develop corrective measures and to ensure the revised Reef 2050 Plan — the overarching framework for protecting the reef to 2050 — addresses the threats.

An in-danger listing is a call to arms to all countries to work together to save the reef from human-caused heating. So the ongoing collaboration between Australia and UNESCO could then enable the Great Barrier Reef’s removal from the in-danger list.

Is Australia suddenly being singled out?

Ley wrote that the Great Barrier Reef was suddenly and unexpectedly “singled out” for an in-danger listing, which she interpreted as a suggestion that “Australia can single-handedly change the emissions trajectory of the whole world”.

However, the dialogue between UNESCO and Australia on the Great Barrier Reef’s protection has a long history. And in making its in-danger recommendation, UNESCO acknowledged Australia “on its own cannot address the threats of climate change”. But UNESCO does appear to have concerns about Australia’s record on emissions reduction.

For example, in 2011 the World Heritage Committee expressed “extreme concern” over the approval for liquefied natural gas facilities on Curtis Island within the boundary of the Great Barrier Reef World Heritage area. A year later, it asked Australia to ensure coastal development isn’t permitted if it effects the outstanding universal value of the property.

In 2012, 2013 and 2014, prior to the annual meetings of the World Heritage Committee, UNESCO raised the possible inscription of the Great Barrier Reef on the in-danger list.

Significantly, in 2017, the World Heritage Committee emphasised the importance of state parties (countries adhering to the world heritage convention, such as Australia) undertaking the most ambitious implementation of the Paris Agreement. This is an important pathway to reduce the risks and impacts of climate change on World Heritage properties.

UNESCO invited all state parties to act on climate change under the Paris Agreement “consistent with their common but differentiated responsibilities and respective capabilities”.

So what are Australia’s responsibilities?

Ley is correct to point out that all 29 World Heritage listed coral reefs, scattered throughout the tropics, are extremely vulnerable to human-caused climate change.

However, Australia is responsible for the world’s largest coral reef system, and has far higher capabilities to reduce greenhouse gas emissions than other, less wealthy countries.

But Australia’s record on protecting ecosystems and people from climate change is comparatively very poor. And despite being responsible for 20 World Heritage Areas, we have one of the highest per capita emission rates in the world.

The federal government continues to spruik a fossil-fuelled, gas-led COVID recovery, with ongoing subsidies for new coal mines. This support for coal and fossil gas is inconsistent with Australia’s commitments to the World Heritage Convention.

Rejecting the science-based assessments by UNESCO is further damaging Australia’s reputation as a laggard on addressing climate change. Surely, Australia can do better.




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The Conversation


Terry Hughes, Distinguished Professor, James Cook University; Jon C. Day, PSM, Adjunct Senior Research Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook University, and Ove Hoegh-Guldberg, Professor, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australian government was ‘blindsided’ by UN recommendation to list Great Barrier Reef as in-danger. But it’s no great surprise


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Jon C. Day, James Cook University; Scott F. Heron, James Cook University, and Terry Hughes, James Cook UniversityThe Australian government on Tuesday expressed shock at a draft decision to list the Great Barrier Reef as “in danger”. But the recommendation has been looming for some time.

The recommendation, by the United Nations Educational, Scientific and Cultural Organisation (UNESCO) and the International Union for Conservation of Nature (IUCN), acknowledges Australia’s commitment to implementing the Reef 2050 Plan, an overarching framework to protect the natural wonder for future generations.

But the “outstanding universal value” of the Great Barrier Reef has continued to decline.

The draft decision will now be considered at the World Heritage Committee meeting, to be held online next month. The development is significant for several reasons – not least that Australia’s progress under the Paris Agreement is being linked to its stewardship of the reef.

Last year, severe bleaching struck all three regions of the Great Barrier Reef.
ARC Centre of Excellence for Coral Reef Studies

What did UNESCO say?

In recommending the in-danger listing, UNESCO and IUCN cited a 2019 report by the Great Barrier Reef Marine Park Authority which found the ecosystem’s long-term outlook had deteriorated from poor to very poor. It said global warming had also triggered coral bleaching events in 2016 and 2017 – which were followed by another mass bleaching event in 2020.

The report said Australia’s progress on the Reef 2050 Plan “has been insufficient in meeting key targets”. It said the plan requires stronger and clearer commitments, in particular on urgently addressing threats from climate change, and improving water quality and land management.

Among other recommendations, the draft decision called on the international community to “implement the most ambitious actions to address climate change […] and fulfil their responsibility to protect the Great Barrier Reef”.




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‘Severely threatened and deteriorating’: global authority on nature lists the Great Barrier Reef as critical


The 2020 coral bleaching event was the second-worst in more than two decades.
ARC Centre of Excellence for Coral Reef Studies

No real surprise

Federal Environment Minister Sussan Ley’s said the government was “blindsided” by the draft recommendation. However the move has been a long time coming.

As noted above, the government’s 2019 Outlook Report documented the impacts and threats to the Great Barrier Reef in no uncertain terms, and identified climate change as the most serious threat.

There were other indicators the recommendation was looming. In 2020, the IUCN World Heritage Outlook listed the Great Barrier Reef as “critical” due to threats including climate change and poor water quality. The rating – the worst on a four-point scale — was a decline from the 2017 rating of “significant concern”.

And in 2018, a report predicted that without major reductions in greenhouse gas emissions, all 29 World Heritage coral reefs, including the Great Barrier Reef, will cease to be “functioning ecosystems by the end of the century”.

Finally in 2012, the World Heritage Committee warned the Great Barrier Reef could be placed on the in-danger list “in the absence of substantial progress”.




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Climate change isn’t the only concern

While climate change is a major concern in the draft decision, it is but one of numerous pressures on the Great Barrier Reef. Poor water quality due to nutrient and sediment runoff – the latter linked to land clearing – are also big problems.

The IUCN outlook report said climate change is the biggest threat to all the world’s natural heritage places. In this regard, this week’s draft decision sets an important precedent for the World Heritage Committee. It would seem the committee is now prepared to directly address the issue of climate change, after being less so inclined in previous years.

The Reef 2050 Plan does not adequately address the climate change threat. The UNESCO report calls on Australia to correct this, and ensure the plan sufficiently addresses other threats including water quality.

Decisions by the World Heritage Committee are not binding on any country. Still, we expect the committee’s concerns to result in Australia amending the Reef 2050 Plan to better acknowledge climate change as a significant issue.

The draft decision will be considered at the annual meeting of the World Heritage Committee in July, chaired by China and comprising 21 countries.

Two snorkelers
Getting placed on the in-danger list isn’t likely to impact tourism.
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An end to tourism?

The experience of other major tourist destinations suggests an in-danger listing may not damage tourism at the Great Barrier Reef, as some have feared.

Take the Everglades in the United States, Belize in the Caribbean and the Galapagos Islands. An analysis of these World Heritage properties showed no discernible tourism downturn after an in-danger listing. However, if the Great Barrier Reef’s condition continues to deteriorate, industries that rely on a healthy Reef are likely to endure long-term damage.

An in-danger listing is not permanent, nor does it mean the Great Barrier Reef will be permanently removed from the World Heritage list. Currently, 53 World Heritage properties are on the in-danger list; others were taken off the list once concerns were addressed.

The Great Barrier Reef will continue to be harmed until nations collectively adopt more ambitious climate goals, global emissions of greenhouse gases fall to net-zero and sea temperatures stabilise.

Without real and urgent actions at all levels — global, national, and local — the values that make all heritage places special will decline. That makes it less likely that future generations will be able to enjoy these wonders as we have done.




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The Conversation


Jon C. Day, PSM, Adjunct Senior Research Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook University; Scott F. Heron, Associate Professor, James Cook University, and Terry Hughes, Distinguished Professor, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Life on the hidden doughnuts of the Great Barrier Reef is also threatened by climate change



A sea cucumber living on the Great Barrier Reef inter-reef seafloor.
Kent Holmes/Nature Ecology and Evolution, Author provided

Mardi McNeil, Queensland University of Technology; Andrew Hoey, James Cook University; Jody Webster, University of Sydney, and Luke Nothdurft, Queensland University of Technology

Mention the Great Barrier Reef, and most people think of the rich beauty and colour of corals, fish and other sea life that are increasingly threatened by climate change.

But there is another part of the Great Barrier Reef that until recently was largely hidden and under-explored.

In the northern section of the Great Barrier Reef Marine Park there are large Halimeda algal habitats called bioherms (also known as doughnuts because of their shape).

They are constructed by a type of algae (Halimeda) with a limestone skeleton. The tops of the bioherms are carpeted by a living meadow of the algae, yet much of the plant community includes other types of green, red and brown algae and some seagrasses.

A type of green seaweed.
Halimeda is a genus of green macroalgae (seaweed).
Mardi McNeil, Author provided

The bioherms cover an area greater than 6,000km², more than twice the area of shallow coral reefs.

Several maps showing the location of the _Halimeda_ bioherms.
The distribution of Halimeda bioherms in the Great Barrier Reef.
Figshare/Mardi McNeil, CC BY

Scientists have known for decades of this unusual inter-reef seafloor habitat that lies between the coast and the outer barrier reefs. But they’ve never investigated the diversity of marine life that lives there, until now.

In a new study published today in Nature Ecology and Evolution, scientists examined the community of plants and animals that inhabit these unique areas.

Let’s go deeper

Most studies of tropical marine biodiversity come from shallow coastal and coral reef habitats. We know a great deal about the biodiversity of these parts of the Great Barrier Reef.

But beyond the vision of scuba divers, deeper inter-reef habitats on the shelf, such as the bioherms, have been largely under-explored.




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In our study, we used a dataset of all the plants and animals recorded from the bioherms and surrounding seafloor habitats. The data came from the Seabed Biodiversity Project, a large study published back in 2007 of the inter-reef biodiversity in the Great Barrier Reef World Heritage Area.

What we found was surprising. An exceptional diversity of marine life and a distinct community was found to be living on the bioherms.

A diverse community

The biodiversity of marine life was up to 76% higher on the bioherms than the surrounding inter-reef habitats. Species richness was especially high for plants and invertebrates.

The average number of fish species per site was about the same in both Halimeda and non-Halimeda habitats. In total, 265 species of fish were observed in the bioherms, including sharks and rays.

Overall, more than 1,200 species of animals were recorded from the bioherms. The majority of these (78%) are invertebrates.

A feather star invertebrate.
Most of the animals living on the Halimeda bioherms are invertebrates, such as this feather star.
Mardi McNeil, Author provided

A distinct community

The composition of plant and animal communities on the bioherms was also distinctly different to the surrounding inter-reef areas.

Some 40% of bioherm species were unique to that habitat in the study area. The community included many sponges, snails and slugs, crabs and shrimps, brittle stars, sea urchins and sea cucumbers.

The fish community on the bioherms was also distinct from surrounding habitats. The two-spot wrasse, threadfin emperor and black-banded damselfish were particularly common.

A small black fish with a yellow tail and a white band near its neck.
A yellowtail angelfish (Chaetodontoplus meredithi) seen in coral waters of the Great Barrier Reef.
Sascha Schultz/iNaturalist.org/FishofAustralia, CC BY-NC

Most interesting about the bioherm fish community was the occurrence of some species such as the yellowtail angelfish generally thought to live mostly on coral reefs. Some of these reef-associated fishes have been increasingly observed in a range of non-reef habitats.

These multi-habitat users may be using the bioherms for shelter, feeding, spawning or as nursery grounds. Understanding the connections between shallow coral reefs and deeper bioherms is important to better understand how the reef and inter-reef habitats function.

An unusual habitat

The Halimeda bioherms are arguably the weirdest habitat in the Great Barrier Reef.

Recent high-resolution seafloor mapping using airborne lasers revealed the bioherms form a seafloor that looks like fields of giant doughnuts 20 metres high and 200 metres across.

The doughnuts are the connected circles on the seafloor in the yellow/green bioherm part. They look quite small but each circle is about 200 metres across.

The tops of the bioherms lie some 25-30 metres below the surface, so can’t be seen from boats passing over.

Deeper water and the remote location has meant the bioherms have been mostly invisible to marine biologists that work on the nearby shallow coral reefs.

Under threat from climate change

We are only just beginning to understand the importance of Halimeda bioherms as a habitat to support biodiversity in the Great Barrier Reef.

But just as the rest of the Great Barrier Reef is likely to be impacted by the effects of climate change, so too are the bioherms.

Potential threats to the bioherms include marine heating, ocean acidification and changes to circulation patterns.




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It has been more than 15 years since the inter-reef Seabed Biodiversity Project. The five-yearly Great Barrier Reef Outlook Report says little is known about any ecological trends in the bioherm habitat.

Our new study provides a baseline of the biodiversity of Halimeda bioherms at a single point in time. But questions remain about the present state of this ecosystem and its resilience on short and long-term physical and biological cycles.

Long-term monitoring of these unique and hidden habitats is critical to more fully understand the overall health of the Great Barrier Reef.The Conversation

Mardi McNeil, Postdoctoral researcher, Queensland University of Technology; Andrew Hoey, Senior Research Fellow, James Cook University; Jody Webster, Professor of Marine Geoscience, University of Sydney, and Luke Nothdurft, Senior Lecturer – Earth Science, Queensland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

‘Severely threatened and deteriorating’: global authority on nature lists the Great Barrier Reef as critical



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Jon C. Day, James Cook University and Scott F. Heron, James Cook University

The Great Barrier Reef is now in “critical” condition and the health of four other Australian World Heritage properties has worsened, according to a sobering report just released by the International Union for Conservation of Nature (IUCN).

The IUCN is the global authority on nature. Its third outlook report marks the first time the IUCN has declared an Australian property as critical, which means its values are severely threatened and deteriorating. The health of the Blue Mountains, Gondwana Rainforests, Shark Bay and the Ningaloo Coast has also been downgraded.




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The assessment, while chastening, is not surprising. The Great Barrier Reef has endured three mass coral bleaching events in five years, and last summer’s bushfires caused untold damage in the Blue Mountains and Gondwana Rainforests (not to mention the current fires at the reef’s Fraser Island).

Climate change remains the key issue for World Heritage places, not just in Australia but globally. In fact, the IUCN assessment found climate change threatens 11 of Australia’s 16 properties. This raises further questions over our national climate response.

World Heritage: the best of the best

The latest report builds on previous reports from 2014 and 2017, and shows the status and trends of World Heritage properties identified for their outstanding natural values. As the report states:

our ability to conserve these sites is thus a litmus test for the broader success of conservation worldwide.

To qualify for World Heritage listing for natural values, a place must meet one or more of four criteria: exceptional beauty, geology, ecological processes, and species and habitats.

Some properties are also recognised for cultural values and, if they have both, they’re referred to as “mixed”. Across the world there are 252 natural and mixed World Heritage properties, of which 16 are in Australia.

The IUCN is the official advisor on nature to UNESCO’s World Heritage Committee. The IUCN Outlook report involves assessments by hundreds of international experts, who examine the conservation prospects of all natural and mixed World Heritage properties. It focuses on their natural values, the threats to these values and the effectiveness of actions to protect them.

Threats to our iconic places

Climate change is now the most prevalent threat to natural World Heritage sites, and to many cultural sites.

Overall, the report assessed climate change as a high or a very high threat in 83 out of 252 global properties (33%). This rate is double in Australia, with climate change listed as a threat to 69% (11 of 16) of Australian properties.

And when considering the four natural criteria individually, climate change is the greatest threat to each. This is likely to get worse in future, as climate change is expected to affect more than three times the number of properties impacted by any other threat.

For many properties, the deteriorated conservation outlook is the result of accumulated threats. Impacts of climate change, like coral bleaching and bushfires, are often exacerbated by other threats. For example, the federal government’s 2019 Outlook Report for the Great Barrier Reef listed 45 threats including climate change. This included poor water quality from land-based runoff, coastal development and fishing.

Aerial view of seagrass meadows and headlands in Shark Bay
Seagrass meadows and headlands in the World Heritage-listed Shark Bay Conservation Area, now rated as ‘good with some concerns’.
Shutterstock

At the time of writing, the website which provides the full rationale behind the IUCN outlook was not yet publicly available. However the threats facing the five downgraded Australian sites are well documented.

These include marine heatwaves, which lead to coral bleaching in the Great Barrier Reef and Ningaloo. In Shark Bay, marine heatwaves also cause seagrass — critical habitat for a vast diversity of species — to die-off. Poor water quality, such as from urban and agricultural run-off, is another big threat to the Great Barrier Reef.




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More frequent and intense bushfires are a problem for the Blue Mountains, Shark Bay, and Gondwana Rainforests. These ancient rainforests, along with Ningaloo and Shark Bay, also face threats of invasive species, diseases and storms.

Punching below our weight

While there have been some successes globally, the threats facing our heritage places are escalating.

Since the 2017 assessment, of the 252 properties analysed globally, 16 (6%) have deteriorated and only eight (3%) showed improvement. Notably, Australia is punching below its weight, with 31% of properties having deteriorated (5 of 16) and zero with improvement.




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All of Australia’s World Heritage properties are recognised as having “highly effective” or “mostly effective” protection and management activities.

But the deterioration of the Great Barrier Reef, the Blue Mountains, Gondwana Rainforests, Shark Bay and Ningaloo Coast casts doubt on whether these actions are an effective response to threats, especially climate change.

A whale shark
Western Australia’s Ningaloo Coast, now downgraded to ‘good with some concerns’, is famous for its vast diversity of wildlife, including whale sharks.
Shutterstock

Australia’s climate response has been widely criticised, most recently by Christiana Figueres, the former chief of the UN Climate Framework. In a keynote to open the Australian Emissions Reductions Summit yesterday, Figueres said:

I have been pretty vocal about my frustration for so many years of the completely unstable, volatile, unpredictable stand and position on climate change in Australia.

“Meeting and beating” Australia’s 2030 emissions targets has been the Morrison government’s catch-cry. But the target lacks ambition and the government hasn’t ruled out using Kyoto carry-over credits to help meet it. The government has also refused to commit to a target of net-zero emissions by mid century, in contrast to the policies of many of our international peers.

Management of non-climate stressors is, and will remain, essential to halt the decline of the values of our properties. But Australia must adopt more ambitious climate goals to avoid losing those values that make our heritage places special, preserving them for future generations.




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Jon C. Day, PSM, Post-career PhD candidate, ARC Centre of Excellence for Coral Reef Studies, James Cook University and Scott F. Heron, Associate professor, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The first step to conserving the Great Barrier Reef is understanding what lives there


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Tom Bridge, James Cook University; Andrea Quattrini, Smithsonian Institution; Andrew Baird, James Cook University, and Peter Cowman, James Cook University

Look at this photo of two coral skeletons below. You’d be forgiven for thinking they’re the same species, or at least closely related, but looks can be deceiving. These two species diverged tens of millions of years ago, probably earlier than our human lineage split from baboons and macaques.

Two white branches of coral
The skeletons of two staghorn coral species with the same ‘bottlebrush’ growth form. They might look similar, but they’re not closely related.
source, Author provided

Scientists have traditionally used morphology (size, shape and colour) to identify species and infer their evolutionary history. But most species were first described in the 19th century, and based solely on features of the coral skeleton visible under a microscope.

Morphology remains important for species recognition. The problem is we don’t know whether a particular morphological feature reflects species ancestry, or evolved independently.

Our new study examined the traditional ideas of coral species and their evolutionary relationships using “phylogenomics” – comparing thousands of DNA sequences across coral species.

Our results revealed the diversity and distributions of corals are vastly different to what we previously thought. It shows we still don’t know many fundamental aspects about the corals on Great Barrier Reef.




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And after three mass bleaching events in five years, not having a handle on the basics could mean our attempts to intervene and help coral survive climate change may have unexpected consequences.

An international team of scientists have developed a new genetic tool that can help them better understand and ultimately work to save coral reefs.

How do we know which species is which?

Despite being one of the best-studied marine ecosystems on Earth, there are fundamental knowledge gaps around the Great Barrier Reef, including:

  1. how many coral species live there?
  2. how do we identify them?
  3. where are they found across the vast Great Barrier Reef ecosystem?

Finding the answers to these questions starts with accurate “taxonomy” – the science of naming and classifying living things.

Identifying species based on how similar they look may seem straightforward. As Darwin famously said, closely related species often share morphological features because they inherited them from a common ancestor.




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However, this can be misleading if two unrelated species independently acquire similar features. This process, called convergent evolution, often occurs when different species are faced with similar ecological challenges.

A classic example of convergent evolution is dolphins and the prehistoric ichthyosaurs. These animals are unrelated, but share many similarities since they both occupy a similar ecological niche.

Ichthyosaurs dominated the world’s oceans for millions of years.

At the other end of the spectrum, morphology can vary considerably within a single species. An alien taxonomist visiting Earth could be forgiven for describing the Chihuahua and the Irish Wolfhound as two distinct species.

Bringing coral taxonomy into the 21st century

We used molecular phylogenetics, a field of research that uses variations in DNA sequences to reconstruct genealogies. From corals to humans, molecular phylogenetics has revolutionised our understanding of the origins and evolution of life on Earth.

Molecular approaches have revolutionised our understanding of the diversity and evolution of corals, shedding light on deeper branches in the coral “tree of life”. But within hyper-diverse, ecologically-important coral groups, such as the staghorn corals from the genus Acropora, we are still in the dark.




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Our new technique addresses this by comparing thousands of key regions across coral genomes (the entire genetic code of an organism) to help identify species in this ecologically important group for the first time. This method will also allow us to identify morphological features that do reflect shared ancestry and help us recognise species when diving in the reef.

About a quarter of all coral species on the Great Barrier Reef are staghorn corals, and they provide much of the three-dimensional structure fishes and many other coral reef animals rely on, just like trees in a forest.

Staghorn coral
Staghorn coral from the Houtman Abrolhos Islands.
Thomas Bridge, Author provided

Unfortunately, staghorn corals are also highly susceptible to threats such as thermal bleaching and crown-of-thorns seastar predation. The future of reefs will be heavily influenced by the fate of staghorn corals.

The risk of ‘silent extinctions’

While we don’t yet know how many coral species occur on the Great Barrier Reef or how widespread they are, many species appear to have far smaller ranges than we previously thought.

For example, we now know some of the corals on Lord Howe Island are endemic to only a few reefs in subtropical eastern Australia and occur nowhere else, not even on the Great Barrier Reef. They evolved in isolation and bleach at much lower temperatures than corals on tropical reefs.

An aerial view of Lord Howe Island
Lord Howe Island is home to the world’s southern-most coral reef.
Shutterstock

This means Lord Howe Island’s corals are of far greater conservation concern than currently recognised, because one severe bleaching event could cause the extinction of these species.




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The risk of “silent extinctions”, where species go extinct without even being noticed, is one of the reasons behind the Australian Academy of Science’s Decadal Plan for Taxonomy, which has led to the ambitious goal to document all Australian species in the next 25 years.

Intervening now may have unexpected consequences

In April, the Reef Restoration and Adaptation Program concept feasibility study found 160 possible interventions to help save the Great Barrier Reef. Proposed interventions include moving corals from warm to cooler waters, introducing genetically-engineered heat-tolerant corals into wild populations, and the harvest and release of coral larvae.

Bleached coral
The Great Barrier Reef has undergone yet another mass bleaching event.
Shutterstock

What could go wrong? Well-intentioned interventions may inadvertently threaten coral communities, for example, through introduction or movement of diseases within the Great Barrier Reef. Cane toads are a famous example of unintended consequences: introduced in the 1930s to control an insect pest, they are now wreaking havoc on Australian ecosystems.

Any intervention affecting the ecology of a system as complex as the Great Barrier Reef requires a precautionary approach to minimise the chance of unintended and potentially negative consequences.

What we need, at this time, is far greater investment in fundamental biodiversity research. Without this information, we are not in a position to judge whether particular actions will threaten the resilience of the reef, rather than enhance it.The Conversation

Tom Bridge, Senior Curator – Corals, James Cook University; Andrea Quattrini, Researcher, Smithsonian Institution; Andrew Baird, Professorial fellow, James Cook University, and Peter Cowman, Research Fellow in Ecosystem Dynamics, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.