Dugong and sea turtle poo sheds new light on the Great Barrier Reef’s seagrass meadows


Samantha J Tol, James Cook University; Alana Grech, James Cook University; Paul York, James Cook University, and Rob Coles, James Cook University

Just like birds and mammals carrying seeds through a rainforest, green sea turtles and dugong spread the seeds of seagrass plants as they feed. Our team at James Cook University’s TropWATER Centre has uncovered a unique relationship in the seagrass meadows of the Great Barrier Reef.

We followed feeding sea turtle and dugong, collecting samples of their floating faecal matter. Samantha then had the unenviable job of sifting through hundreds of smelly samples to find any seagrass seeds. These seeds range in size from a few centimetres to a few millimetres, and therefore can require the assistance of a microscope to be found. Once any seeds were found, they were stained with a chemical dye (Tetrazolium) to see if they were still viable (capable of growing).

PhD candidate Samantha Tol holding dugong poo collected from Cleveland Bay in Townsville.
TropWATER, JCU

Why is this important for turtles and dugong?

Green sea turtles and dugong are iconic animals on the reef, and seagrass is their food. Dugong can eat as much as 35 kilograms of wet seagrass a day, while sea turtles can eat up to 2.5% of their body weight per day. Without productive seagrass meadows, they would not survive.

This relationship was highlighted in 2010-11 when heavy flooding and the impact of tropical cyclone Yasi led to drastic seagrass declines in north Queensland. In the year following this seagrass decline there was a spike in the number of starving and stranded sea turtles and dugong along the entire Queensland coast.

The seagrass team at James Cook University has been mapping, monitoring and researching the health of the Great Barrier Reef seagrasses for more than 30 years. While coral reefs are more attractive for tourists, the Great Barrier Reef World Heritage Area actually contains a greater area of seagrass than coral, encompassing around 20% of the world’s seagrass species. Seagrass ecosystems also maintain vibrant marine life, with many fish, crustaceans, sea stars, sea cucumbers, urchins and many more marine animals calling these meadows their home.

These underwater flowering plants are a vital component of the reef ecosystem. Seagrasses stabilise the sediment, sequester large amounts of carbon from the atmosphere and filter the water before it reaches the coral reefs. Further, the seagrass meadows in the Great Barrier Reef support one of the largest populations of sea turtles and dugong in the world.

Seagrass meadows are more connected than we thought

Samantha’s research was worth the effort. There were seeds of at least three seagrass species in the poo of both sea turtles and dugong. And lots of them – as many as two seeds per gram of poo. About one in ten were viable, meaning they could grow into new plants.

Based on estimates of the number of animals in the coastal waters, the time it takes for food to pass through their gut, and movement data collected from animals fitted with satellite tags, there are potentially as many as 500,000 viable seeds on the move each day in the Great Barrier Reef. These seeds can be transported distances of up to 650km in total.

Green Island seagrass meadow exposed at low tide.
TropWATER, JCU

This means turtles and dugong are connecting distant seagrass meadows by transporting seeds. Those seeds improve the genetic diversity of the meadows and may help meadows recover when they are damaged or lost after cyclones. These animals help to protect and nurture their own food supply, and in doing so make the reef ecosystem around them more resilient.

Understanding recovery after climate events

Seagrass meadows have been under stress in recent years. A series of floods and cyclones has left meadows in poor condition, and recovery has been patchy and site-dependent.

This research shows that these ecosystems have pathways for recovery. Provided we take care with the environment, seagrasses may yet recover without direct human intervention.

The ConversationThis work emphasises how much we still have to learn about how the reef systems interconnect and work together – and how much we need to protect every part of our marvellous and amazing reef environment.

Samantha J Tol, PhD Candidate, James Cook University; Alana Grech, Assistant Director, ARC Centre of Excellence for Coral Reef Studies, James Cook University; Paul York, Senior Research Scientist in Marine Biology, James Cook University, and Rob Coles, Team leader, Seagrass Habitats, TropWATER, James Cook University

This article was originally published on The Conversation. Read the original article.

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$500 million for the Great Barrier Reef is welcome, but we need a sea change in tactics too



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The new funding is focused on measures that are already in the foreground.
Robert Linsdell/Flickr, CC BY

Jon Brodie, James Cook University

The federal government’s announcement of more than A$500 million in funding for the Great Barrier Reef is good news. It appears to show a significant commitment to the reef’s preservation – something that has been lacking in recent years.

The new A$444 million package, which comes in the wake of the A$60 million previously announced in January, includes:

  • A$201 million to improve water quality by cutting fertiliser use and adopting new technologies and practices

  • A$100 million for research on coral resilience and adaptation

  • A$58 million to continue fighting crown-of-thorns starfish

  • A$45 million for community engagement, particularly among Traditional Owners

  • A$40 million to enhance monitoring and management on the GBR.

A spokesperson for federal environment minister Josh Frydenberg said the funding would be available immediately to the Great Barrier Reef Foundation, and that there was no predetermined time frame for the spending.

But one concern with the package is that it seems to give greatest weight to the strategies that are already being tried – and which have so far fallen a long way short of success.

Water quality

The government has not yet announced the timelines for rollout of the program. But if we assume that the A$201 million is funding for the next two years, this matches the current rate of water quality management funding – A$100 million a year, which has been in place since 2008.

Yet it is already clear that this existing funding is not reducing pollution loads on the GBR by the required extent. The federal and Queensland governments’ own annual report cards for 2015 and 2016 reveal limited success in improving water quality. It is also known from joint Australian and Queensland government analyses that the required funding to meet water quality targets is of the order of A$1 billion per year over the next 10 years.

In the region’s main industries, such as sugarcane cultivation and beef grazing, most land is still managed using methods that are well below best practice for water quality, such as fertiliser rates of application in sugarcane cultivation. According to the 2017 Scientific Consensus Statement on the GBR’s water quality, very limited progress has been made so far.

Progress towards targets and assigned scores in the 2015 Great Barrier Reef Report Card.
2017 Scientific Consensus Statement, Author provided

The respective load reduction targets set for 2018 and 2025 are highly unlikely to be met at current funding levels. For example, shown below are the current projections for levels of dissolved inorganic nitrogen (DIN).

Progress on reducing total GBR wide dissolved inorganic nitrogen loads and trajectories towards targets.
CREDIT, Author provided

This likely failure to meet any of the targets was noted by UNESCO in 2015 and again in 2017 as a major concern, amid deliberations on whether to put the GBR on the World Heritage in Danger list. The UNESCO report criticised Australia’s lack of progress towards achieving its 2050 water quality targets and failure to pass land clearing legislation.

As the 2017 Scientific Consensus Statement also pointed out, improvements to land management oversight are “urgently needed”. Continued government spending on the same programs, at the same levels, and with no federal legislation to mandate improvements, is unlikely to bring water pollution to acceptable levels or offer significant protection to the GBR.

In contrast to the federal government, the Queensland government is taking what are likely to be more effective measures to manage water quality. These include regulations such as the revised Vegetation Management Act, which is likely to be passed by the parliament in the next few weeks; and the updated Reef Protection Act, currently out for review. Queensland is also directing funds towards pollution hotspots under the Major Integrated Projects framework.




Read more:
Cloudy issue: we need to fix the Barrier Reef’s murky waters


Crown-of-thorns starfish

The government’s new package has pledged A$58 million for further culling of this coral-eating animal. Yet the current culling program has faced serious criticism over its effectiveness.

Udo Engelhardt, director of consultancy Reefcare International, and a pioneer in the control of crown-of-thorns starfish, has claimed that his analysis of the culling carried out in 2013-15 in reef areas off Cairns and to the south of Cairns, reveals a “widespread and consistent failure” to protect coral cover.

Nor does there seem to have been a major independent review of the program since these findings came to light. Without one, it seems a shaky bet to assume that we will expect any more success simply by continuing to fund it.

Overcoming crown-of-thorns starfish might take some more creative thinking.
Paul Asman/Jill Lenoble/Wikimedia Commons, CC BY

Reef restoration

Similar question marks hover over the A$100 million being provided to harness the best science to help restore and protect the reef, and to study the most resilient corals. Like other aspects of the package, the government has not yet promised a timeline on which to roll out the funds.

While reef restoration may be significant for the long-term (decades to centuries) status of the GBR, it is hard to believe that these studies will help within the coming few decades. And even long-term success will hinge either on our ability to stabilise the climate, or on science’s ability to keep pace with the rate of future change.

In the meantime, reef restoration seems at best to be a band-aid that could preserve select tourism sites, but is inconceivable on the scale of the entire GBR.




Read more:
Not out of hot water yet: what the world thinks about the Great Barrier Reef


Herein lies the most significant criticism of the new funding package. It avoids any mention of reducing Australia’s greenhouse gas emissions, or of working closely with the international community to help deliver significant global reductions. Yet climate change is routinely described as the biggest threat to the reef.

The ConversationThe new announcement dodges that issue, while providing a moderate amount of funding for the continuation of largely unsuccessful programs. Given that the new funding is to be managed by the Great Barrier Reef Foundation – which is a charity rather than a statutory management body – we can only hope that the foundation finds new and innovative ways to improve greatly on the current efforts.

Jon Brodie, Professorial Fellow, ARC Centre of Excellence for Coral Reef Studies, James Cook University

This article was originally published on The Conversation. Read the original article.

How the 2016 bleaching altered the shape of the northern Great Barrier Reef



File 20180418 163978 1aql97h.jpg?ixlib=rb 1.1
Staghorn and tabular corals suffered mass die-offs, robbing many individual reefs of their characteristic shapes.
ARC Centre of Excellence for Coral Reef Studies/ Mia Hoogenboom

Selina Ward, The University of Queensland

In 2016 the Great Barrier Reef suffered unprecedented mass coral bleaching – part of a global bleaching event that dwarfed its predecessors in 1998 and 2002. This was followed by another mass bleaching the following year.

This was the first case of back-to-back mass bleaching events on the reef. The result was a 30% loss of corals in 2016, a further 20% loss in 2017, and big changes in community structure. New research published in Nature today now reveals the damage that these losses caused to the wider ecosystem functioning of the Great Barrier Reef.

Fast-growing staghorn and tabular corals suffered a rapid, catastrophic die-off, changing the three-dimensional character of many individual reefs. In areas subject to the most sustained high temperatures, some corals died without even bleaching – the first time that such rapid coral death has been documented on such a wide scale.




Read more:
It’s official: 2016’s Great Barrier Reef bleaching was unlike anything that went before


The research team, led by Terry Hughes of James Cook University, carried out extensive surveys during the two bleaching events, at a range of scales.

First, aerial surveys from planes generated thousands of videos of the reef. The data from these videos were then verified by teams of divers in the water using traditional survey methods.

Finally, teams of divers took samples of corals and investigated their physiology in the laboratory. This included counting the density of the microalgae that live within the coral cells and provide most of the energy for the corals.

The latest paper follows on from earlier research which documented the 81% of reefs that bleached in the northern sector of the Great Barrier Reef, 33% in the central section, and 1% in the southern sector, and compared this event with previous bleaching events. Another previous paper documented the reduction in time between bleaching events since the 1980s, down to the current interval of one every six years.

Different colour morphs of Acropora millepora, each exhibiting a bleaching response during mass coral bleaching event.
ARC Centre of Excellence for Coral Reef StudiesStudies/ Gergely Torda

Although reef scientists have been predicting the increased frequency and severity of bleaching events for two decades, this paper has some surprising and alarming results. Bleaching events occur when the temperature rises above the average summer maximum for a sufficient period. We measure this accumulated heat stress in “degree heating weeks” (DHW) – the number of degrees above the average summer maximum, multiplied by the number of weeks. Generally, the higher the DHW, the higher the expected coral death.

The US National Oceanic and Atmospheric Administration has suggested that bleaching generally starts at 4 DHW, and death at around 8 DHW. Modelling of the expected results of future bleaching events has been based on these estimates, often with the expectation the thresholds will become higher over time as corals adapt to changing conditions.

In the 2016 event, however, bleaching began at 2 DHW and corals began dying at 3 DHW. Then, as the sustained high temperatures continued, coral death accelerated rapidly, reaching more than 50% mortality at only 4-5 DHW.

Many corals also died very rapidly, without appearing to bleach beforehand. This suggests that these corals essentially shut down due to the heat. This is the first record of such rapid death occurring at this scale.

This study shows clearly that the structure of coral communities in the northern sector of the reef has changed dramatically, with a predominant loss of branching corals. The post-bleaching reef has a higher proportion of massive growth forms which, with no gaps between branches, provide fewer places for fish and invertebrates to hide. This loss of hiding places is one of the reasons for the reduction of fish populations following severe bleaching events.




Read more:
The world’s coral reefs are in trouble, but don’t give up on them yet


The International Union for Conservation of Nature (IUCN), which produces the Red List of threatened species, recently extended this concept to ecosystems that are threatened with collapse. This is difficult to implement, but this new research provides the initial and post-event data, leaves us with no doubt about the driver of the change, and suggests threshold levels of DHWs. These cover the requirements for such a listing.

Predictions of recovery times following these bleaching events are difficult as many corals that survived are weakened, so mortality continues. Replacement of lost corals through recruitment relies on healthy coral larvae arriving and finding suitable settlement substrate. Corals that have experienced these warm events are often slow to recover enough to reproduce normally so larvae may need to travel from distant healthy reefs.

Although this paper brings us devastating news of coral death at relatively low levels of heat stress, it is important to recognise that we still have plenty of good coral cover remaining on the Great Barrier Reef, particularly in the southern and central sectors. We can save this reef, but the time to act is now.

This is not just for the sake of our precious Great Barrier Reef, but for the people who live close to reefs around the world that are at risk from climate change. Millions rely on reefs for protection of their nations from oceanic swells, for food and for other ecosystem services.

The ConversationThis research leaves no doubt that we must reduce global emissions dramatically and swiftly if we are save these vital ecosystems. We also need to invest in looking after reefs at a local level to increase their chances of surviving the challenges of climate change. This means adequately funding improvements to water quality and protecting as many areas as possible.

Selina Ward, Senior Lecturer, School of Biological Sciences, The University of Queensland

This article was originally published on The Conversation. Read the original article.

Citizens of the Great Barrier Reef: going beyond our backyard to protect the reef



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Photo Jorge Alvarez Romero.

Georgina Gurney, James Cook University

From place-based to problem-based campaigns, we are seeing a rise in initiatives aiming to foster collective environmental stewardship among concerned citizens across the globe. These international communities have arisen to meet new environmental challenges and seize the opportunities presented by our increasingly connected world.

Traditional approaches to community engagement have tended to focus only on the involvement of local people. However, the recently launched Citizens of the Great Barrier Reef initiative highlights the changing nature of community engagement aimed at fostering environmental stewardship.

In a globalised world, maintaining treasures like the Great Barrier Reef and other ecosystems affected by global-scale threats demands new approaches that involve participation not only of people living locally, but also those in distant places.

A connected world

Today’s environmental problems tend to be characterised by social and environmental connections with distant places.

In terms of environmental connections, places such as the Great Barrier Reef are increasingly affected by global threats. These include: poor water quality associated with port dredging driven by international mining; reef fisheries influenced by national and international markets; and, most importantly, coral bleaching caused by climate change. Social and political action beyond the local is need to combat these threats.




Read more:
Coral bleaching comes to the Great Barrier Reef as record-breaking global temperatures continue


Social connections are increasing through both ease of travel and social media and other forms of virtual communication. This provides opportunities to engage more people across the globe to take meaningful action than ever before. People are able to form and maintain attachments to special places no matter where they are in the world.

Our recent research, involving more than 5,000 people from over 40 countries, shows that people living far from the Great Barrier Reef can have strong emotional bonds comparable to locals’ attachments. These bonds can be strong enough to motivate them to take action.

Harnessing social media

Increasing social connections across the globe don’t only allow people in distant locations to maintain their attachments to a place. They also provide a vehicle to leverage those attachments into taking meaningful actions to protect these places.

Such strategies can now be used even in the most remote of locations – such as 60 metres above the forest floor in a remote part of Tasmania.

During her 451-day tree sit, activist Miranda Gibson co-ordinated an online action campaign. She was able to engage a global audience through blogging, live streaming and posting videos and photos.




Read more:
Digital tree-sitting: environmental protest when media is everywhere


Social media provide a new way to foster a sense of community among people far and wide. In this sense, “community” doesn’t have to be local; individuals with common interests and identities can share a sense of community globally. Indeed, this is a key ingredient for collective action.

Employing images and language targeted to appeal to people’s shared attachments to a place can help increase collective stewardship of that place.

These global communities reflect “imagined communities”, a concept developed by political scientist Benedict Anderson to analyse nationalism. Anderson suggests that nations are imagined in the sense that members “will never know most of their fellow members or even hear of them, yet in the minds of each lives the image of their communion”.

Such communities of environmental stewardship can have significant impact. For example, this type of community – which UTAS Professor Libby Lester termed “transnational communities of concern” – played a key role in the decline in Japanese market demand for Tasmanian forest products.

Beyond slacktivism

An important challenge in engaging distant communities in environmental stewardship is to avoid the pitfalls of “slacktivism”.

This refers to the phenomenon of people taking online actions that require little effort, such as joining a Facebook group. It makes them feel good about contributing to a cause but can stop them from taking further action that has real on-the-ground impacts.




Read more:
‘Slacktivism’ vs ‘snarktivism’: how do you take your online activism?


More meaningful options are available to people in remote places that can result in real change. These include lobbying national governments, international organisations (such as the World Heritage Committee), or transnational corporations (to prioritise corporate social responsibility, for example). Most organisations that have successfully engaged distant people in environmental stewardship, including Fight for Our Reef, have tended to take a political approach to help with lobbying efforts.

Other meaningful actions that can be undertaken remotely include supporting relevant NGOs and reducing individual consumption.

A new approach to global citizenship

The Citizens for the Reef emphatically state that they are “not looking for Facebook likes” but seek “real action”.

The six actions being promoted include reducing consumption of four disposable products, eliminating food wastage, and financially supporting crown-of-thorns starfish control. Signed-up citizens are given an “impact score”, based on undertaking these actions and recruiting others, and can compare their progress to others around the world.

The initiative provides an example of a new form of environmental activism that is emerging in response to increasing global environmental and social connection. The significant challenge for this initiative is to gain the sustained engagement of enough people to achieve real-world impact.

The ConversationUltimately, however, while the local to global public certainly have a critical part to play in addressing these threats, this does not diminish the responsibility of government and the private sector for safeguarding the future livelihood of the Great Barrier Reef.

Georgina Gurney, Environmental Social Science Research Fellow, James Cook University

This article was originally published on The Conversation. Read the original article.

$60 million to save the Great Barrier Reef is a drop in the ocean, but we have to try


David Suggett, University of Technology Sydney

The Great Barrier Reef has never faced such a dire future. Amid increasingly doom-laden headlines, the federal government this week unveiled a recovery package aimed at securing the reef’s prospects. The question is whether this is indeed a rescue, or just a smokescreen of false hope.

The A$60 million package will be split between various projects:

  • A$36.6 million will be spent on reducing the runoff of land-based agricultural fertilisers and pesticides onto the reef

  • A$10.4 million will go towards an “all-out assault” on the coral-eating crown-of-thorns starfish

  • A$4.9 million will fund improved monitoring and early warning of issues such as mass bleaching

  • A$6 million will be spent on a new national Reef Restoration and Adaptation program.

But what return can we expect for this A$60 million investment, which is only 0.1% of the A$56 billion estimated economic value of the Great Barrier Reef?

Value for money

At face value, splitting the funding across several priority areas seems logical. Many local stressors, from pollution to overfishing, affect the Great Barrier Reef in different ways and in different places, so tackling them locally seems like a nice direct way to intervene.

But here’s the problem: these stressors interact and amplify each others’ effects. This means that spreading the money so thinly is a risky move, because successfully tackling any one problem rests on successfully tackling all the others.

Crown-of-thorns starfish is a great example. Even if we can remove or destroy them in sufficient numbers to make a difference, their populations will simply bounce back unless we also reduce the agricultural pollution that feeds their larvae. Alongside this, we need to ensure that their natural predators such as the giant triton mollusc also thrive.

Local impacts on the Great Barrier Reef are also amplified by global climate factors, such as the warming and increased ocean acidity caused by rising atmospheric carbon dioxide levels.

Focusing purely on local issues risks diverting attention from this wider problem. The unprecedented back-to-back mass bleaching that catastrophically damaged the Great Barrier Reef in 2016 and 2017 was a direct result of global climate change.

Preventing this from accelerating further requires global and collective
action on greenhouse gas emission reductions. As custodian of the Great Barrier Reef, as well as a major coal exporter and a signatory to the Paris Climate Agreement, Australia has a responsibility to lead from the front to find alternatives to fossil fuels.

For this reason, the new funding package has unsurprisingly been criticised for not attempting to “cure” the ultimate problem that ails the Great Barrier Reef. Local interventions such as the ones being funded are often called out for being band-aid solutions. But the reality is that we need band-aids more than ever – although perhaps “tourniquets” would be more apt.

Cutting emissions and curbing climate change must remain our absolute priority.
However, even relatively optimistic emissions reduction scenarios will leave us
with warmer and acidic reefs for the coming decades. This means we will have to think well outside the box if we are to ensure that the Barrier Reef stays great. We cannot deny treatment while we attempt to find the cure.




Read more:
The Great Barrier Reef can repair itself, with a little help from science


The problem is that most current local reef interventions are considered too risky or too expensive, and are therefore dismissed without trying them. But unless we try alternatives, and are prepared to learn by trial and error, how can we find the solutions that work? What the government’s new package ultimately therefore provides is the incentive to innovate.

In this sense it follows parallel calls from the Queensland government to find new ways to boost coral abundance. As such, the federal funding may only be successful if we ensure that the proposed investment focuses on tackling the priority areas in new ways, rather than simply scaling up the current efforts.

As the stress builds on the Great Barrier Reef, one thing is certain: its future will depend on maximising its resilience. This necessarily calls for a range of efforts, focusing on biology, ecosystems, and changing human behaviour – not just defaulting to a single solution. Intensifying efforts to harness corals that are already adapted to extreme conditions will likely be crucial.

The ConversationAnd of course, all of this will count for nothing unless we also take parallel action to tackle the underlying problem: climate change.

David Suggett, Associate Professor in Marine Biology, University of Technology Sydney

This article was originally published on The Conversation. Read the original article.

How can we halt the feminisation of sea turtles in the northern Great Barrier Reef?


Ana Rita Patricio, University of Exeter

In the northern part of Australia’s Great Barrier Reef, the future for green sea turtles appears to be turning female.

A recent study has revealed that climate change is rapidly leading to the feminisation of green turtles in one of the world’s largest populations. Only about 1% of these juvenile turtles are hatching male.


Read more: What does climate change mean for sea turtles?


Among sea turtles, incubation temperatures above 29ºC produce more female offspring. When incubation temperatures approach 33ºC, 100% of the offspring are female. Cooler temperatures yield more males, up to 100% near a lower thermal limit of 23ºC. And if eggs incubate at temperatures outside the range of 23-33ºC the risk of embryo malformation and mortality becomes very high.

As current climate change models foresee increases in average global temperature of 2 to 3ºC by 2100, the future for these turtles is in danger. Worryingly, warmer temperatures will also lead to ocean expansion and sea-level rise, increasing the risk of flooding of nesting habitats.

How scientists are tackling the problem

Green sea turtles’ sensitivity to incubation temperatures is such that even a few degrees can dramatically change the sex ratio of hatchlings.

Sea turtles are particularly vulnerable because they have temperature-dependent sex determination, or TSD, meaning that the sex of the offspring depends on the incubation temperature of the eggs. This is the same mechanism that determines the sex of several other reptile species, such as the crocodilians, many lizards and freshwater turtles.

Scientists and conservationists are well aware of how future temperatures may threaten these species. For the past two decades they have been investigating the incubation conditions and resulting sex ratios at several sea turtle nesting beaches worldwide.

This is mostly done using temperature recording devices (roughly the size of an egg). These are placed inside nest chambers among the clutch of eggs, or buried in the sand at the same depth as the eggs. When a clutch hatches (after 50 to 60 days) the device is recovered and the temperatures recorded are analysed.

Research has revealed that most nesting beaches studied to date have sand temperatures that favour female hatchling production. But this female bias is not immediately a bad thing, because male sea turtles can mate with several females (polygyny). So having more females actually enhances the reproductive potential of a population (i.e. more females equals more eggs).

But given that climate change will likely soon increase this female bias, important questions arise. How much of a female bias is OK? Will there be enough males? What is the minimum proportion of males to keep a sustainable population?

These questions are being investigated. But, in the meantime, alarming reports of populations with more than 99% of hatchlings being female stress the urgency of science-based management strategies. These strategies must be designed to promote (or maintain) cooler incubation temperatures at key nesting beaches to prevent population decline or even extinction.

The challenge of reversing feminisation

There are two general approaches to the problem:

  1. mitigate impacts at the most endangered nesting beaches
  2. identify and protect sites that naturally produce higher proportions of males.

Several studies emphasise that the natural shading native vegetation provides is essential to maintain cooler incubation temperatures. Thus, a key conservation action is to protect beach vegetation, or reforest nesting beaches.

Coastal vegetation also protects the nesting beach against wave erosion during storms, which will worsen under climate change. This strategy further requires coastal development to allow for buffer zones. Construction setback regulations should be enforced or implemented.

When natural shading is not an option, clutches of eggs can be moved either to more suitable beaches, or to hatcheries with artificial shading. Researchers have tested the use of synthetic shade cloth and found it is effective in reducing sand and nest temperatures.

Other potential strategies involve adding light-coloured sand on top of nests. This can help by absorbing less solar radiation (heat) compared to darker sand. Beach sprinklers have also been tested to simulate the cooling effect of rainfall.

The effectiveness of these actions has yet to be fully tested, but there is concern about some potential negative side effects. For example, excess water from sprinklers may cause fungal infections on eggs.

Finally, as much as mitigation measures are important, these are always short-term solutions. In the long run, prevention is always the best strategy, i.e. protecting the nesting beaches that currently produce more males from deforestation, development and habitat degradation.

Our recent research on the largest green turtle population in Africa reports unusually high male hatchling production. We found almost balanced hatchling sex ratios (1 female to 1.2 males). We attributed this mostly to the cooling effect of the native forest.

This, and similar nesting beaches, should be designated as priority conservation sites, as they will be key to ensuring the future of sea turtles under projected global warming scenarios.

Sea turtles face an uncertain future

Sea turtles are resilient creatures. They have been around for over 200 million years, surviving the mass extinction that included the dinosaurs, and enduring dramatic climatic changes in the past.

There is potential for these creatures to adapt, as they did before. This could be through, for example, shifting the timing of nesting to cooler periods, changing their distribution to more suitable habitats, or evolution of critical incubation temperatures that produce males.


Read more: Turtle hatchlings lend each other a flipper to save energy


But the climate today is changing at an unprecedented rate. Along with the feminisation of these turtles in the northern Great Barrier Reef, sea turtles globally face many threats from humans. These include problems associated with by-catch, poaching, habitat degradation and coastal development, plus a history of intense human exploitation.

The ConversationIn 2018, the prevalence of these species depends now more than ever on the effectiveness of conservation measures.

Ana Rita Patricio, Postdoctoral research fellow, University of Exeter

This article was originally published on The Conversation. Read the original article.

It’s official: 2016’s Great Barrier Reef bleaching was unlike anything that went before


Sophie Lewis, Australian National University and Jennie Mallela, Australian National University

It is no longer news that the Great Barrier Reef has suffered extreme bleaching.

In early 2016, we heard that the reef had suffered the worst bleaching ever recorded. Surveys published in June that year estimated that 93% of coral on the vast northern section of the reef was bleached, and 22% had already been killed.

Further reports from this year show that bleaching again occurred. The back-to-back bleaching hit more than two-thirds of the Great Barrier Reef and may threaten its UNESCO World Heritage listing.

After recent years of damage, what does the future hold for our priceless reef?

Our new research, published in the Bulletin of the American Meteorological Society’s special report on climate extremes, shows the news isn’t good for the Great Barrier Reef’s future.


Read more: How to work out which coral reefs will bleach, and which might be spared


Coral reefs are complex ecosystems that are affected by many factors. Changes in sea surface temperatures, rainfall, cloudiness, agricultural runoff, or water quality can affect a reef’s health and resilience to stress.

Early analysis of the 2016 bleaching suggested that the Great Barrier Reef was suffering from thermal stress brought on by human-caused climate change.

Our study took a new and comprehensive approach to examine these multiple climatic and environmental influences.

We set out to answer the crucial question: could anything else have bleached the Great Barrier Reef, besides human-induced climate change?

Clear fingerprint

The results were clear. Using a suite of climate models, we found that the significant warming of the Coral Sea region was likely caused by greenhouse gases from human activities. This warming was the primary cause of the extreme 2016 bleaching episode.

But what about those other complex factors? The 2016 event coincided with an El Niño episode that was among the most severe ever observed. The El Niño-Southern Oscillation system, with its positive El Niño and negative La Niña phases, has been linked to bleaching of various coral reefs in the past.

Our study showed that although the 2016 El Niño probably also contributed to the bleaching, this was a secondary contributor to the corals’ thermal stress. The major factor was the increase in temperatures because of climate change.

We next analysed other environmental data. Previous research has found that corals at sites with better water quality (that is, lower concentrations of pollution particles) are more resilient and less prone to bleaching.

Pollution data used in our study show that water quality in 2016 may have been better than in previous bleaching years. This means that the Great Barrier Reef should have been at lower risk of bleaching compared to long-term average conditions, all else being equal. Instead, record bleaching hit the reef as a result of the warming temperature trend.

Previous events

The final part of our investigation involved comparing the conditions behind the record 2016 bleaching with those seen in previous mass bleaching episodes on the Great Barrier Reef, in 1997-98 and 2010-11.

When we analysed these previous events on the Reef, we found very different factors at play.

In 1997-98 the bleaching coincided with a very strong El Niño event. Although an El Niño event also occurred in 2016, the two were very different in terms of the distribution of unusually warm waters, particularly in the eastern equatorial Pacific. In 1997-98, the primary cause of the bleaching – which was less severe than in 2016 – was El Niño.

In 2010-11, the health of the Great Barrier Reef was impaired by runoff. That summer brought record high rainfall to eastern Australia, causing widespread flooding across Queensland. As a result of the discharge of freshwater onto the reef reducing the salinity, bleaching occurred.


Read more: Feeling helpless about the Great Barrier Reef? Here’s one way you can help


There have been many reports in recent years warning of trouble for the Great Barrier Reef. Sadly, our study is yet another warning about the reef’s future – perhaps the most comprehensive warning yet. It tells us that the 2016 bleaching differed from previous mass bleaching events because it was driven primarily by human-induced climate warming.

This puts the Great Barrier Reef in grave danger of future bleaching from further greenhouse warming. The local environmental factors that have previously helped to protect our reefs, such as good water quality, will become less and less able to safeguard corals as the oceans warm.

The ConversationNow we need to take immediate action to reduce greenhouse gas emissions and limit further warming. Without these steps, there is simply no future for our Great Barrier Reef.

Sophie Lewis, Research fellow, Australian National University and Jennie Mallela, Research Fellow in Coral Reef Monitoring and Reef Health Appraisal, Australian National University

This article was originally published on The Conversation. Read the original article.