How we found 112 ‘recovery reefs’ dotted through the Great Barrier Reef


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Some reefs are strong sources of coral larvae.
Peter Mumby, Author provided

Peter J Mumby, The University of Queensland

The Great Barrier Reef is better able to heal itself than we previously imagined, according to new research that identifies 112 individual reefs that can help drive the entire system towards recovery.

The back-to-back bleaching events in 2016 and 2017 that killed many corals on the Great Barrier Reef have led many researchers to ask whether and how it can recover. Conventionally, we tend to focus on what controls recovery on individual reefs – for example, whether they are fouled by seaweed or sediments.

But in our study, published in PLoS Biology, my colleagues and I stepped back to view the entire Great Barrier Reef as a whole entity and ask how it can potentially repair itself.


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


We began by asking whether some reefs are exceptionally important for kick-starting widespread recovery after damage. To do this we set three criteria.

First, we looked for reefs that are major sources of coral larvae – the ultimate source of recovery. Every year corals engage in one of nature’s greatest spectacles, their mass reproduction during a November full moon. Fertilised eggs (larvae) travel on ocean currents for days or weeks in search of a new home.

With our partners at the CSIRO we’ve been able to model where these larvae go, and therefore the “connectivity” of the reef. By using this modelling (the Great Barrier Reef is far too large to observe this directly), we looked for reefs that strongly and consistently supply larvae to many other reefs.

Healthy reefs supply far more larvae than damaged ones, so our second criterion was that reefs should have a relatively low risk of being impacted by coral bleaching. Using satellite records of sea temperature dating back to 1985, we identified reefs that have not yet experienced the kind of temperature that causes mass coral loss. That doesn’t mean these reefs will never experience bleaching, but it does mean they have a relatively good chance of surviving at least for the foreseeable future.

Our final criterion was that reefs should supply coral larvae but not pests. Here we focused on the coral-eating crown-of-thorns starfish, whose larvae also travel on ocean currents. We know that outbreaks of these starfish tend to begin north of Cairns, and from that we can predict which reefs are most likely to become infested over time.

Fortunately, many good sources of coral larvae are relatively safe from crown-of-thorns starfish, particularly those reefs that are far offshore and bathed in oceanic water from the Coral Sea rather than the currents that flow past Cairns. Indeed, the access to deep – and often cooling – ocean water helps moderate temperature extremes in these outer reefs, which also reduces the risk of bleaching in some areas.

Using these three criteria, we pinpointed 112 reefs that are likely to be important in driving reef recovery for the wider system. They represent only 3% of the reefs of the Great Barrier Reef, but are so widely connected that their larvae can reach 47% of all the reefs within a single summer spawning season.

Unfortunately, their distribution across the reef is patchy. Relatively few are in the north (see map) so this area is relatively vulnerable.

Black dots show reefs identified as strong sources of coral larvae; grey dots show other reefs.
Hock et al., PLoS Biol.

Our study shows that reefs vary hugely, both in their exposure to damage and in their ability to contribute to the recovery of corals elsewhere. Where these patterns are pretty consistent over time – as is the case for the reefs we identified – it makes sense to factor this information into management planning.

It would be sensible to improve surveillance of these particular reefs, to check that crown-of-thorns starfish do not reach them, and to eradicate the starfish if they do.

To be clear, these are not the only reefs that should be managed. The Great Barrier Reef already has more than 30% of its area under protection from fishing, and many of its other individual reefs are important for tourism, fisheries and cultural benefits.

But the point here is that some reefs are far more important for ecosystem recovery than others. Factoring these patterns into tactical management – such as how best to respond in the aftermath of a cyclone strike – is the next step. It’s a need that has been articulated repeatedly by the Great Barrier Reef Marine Park Authority.


Read more: Coal and climate change: a death sentence for the Great Barrier Reef


Taking the long-term view, the greatest threats to the reef are rising sea temperatures and ocean acidification caused by elevated carbon dioxide levels. This is clearly a challenge for humanity and one that requires consistent policies across governments.

But local protection is vital in order to maintain the reef in the best state possible given the global environment. Actions include improvements to the quality of the water emerging from rivers, controlling crown-of-thorns starfish, and maintaining healthy fish populations.

The ConversationThis is an expensive process and resources need to be deployed as effectively as possible. Our results help target management effectively by revealing the underlying mechanisms of repair on the reef. If management can help protect and facilitate corals’ natural processes of recovery, this might go a long way towards sustaining the Great Barrier Reef in an already challenging environment.

Peter J Mumby, Chair professor, The University of Queensland

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

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Mexico: New Ocean Reserve


The link below is to an article reporting on the creation of a new vast ocean reserve by Mexico in the Pacific Ocean.

For more visit:
https://www.theguardian.com/environment/2017/nov/25/mexico-creates-vast-new-ocean-reserve-to-protect-galapagos-of-north-america

Explainer: mass coral spawning, a wonder of the natural world


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During mass spawning events coral young rise from their parents to ocean surface.
Australian Institute of Marine Science, Author provided

Line K Bay, Australian Institute of Marine Science; Andrew Heyward, Australian Institute of Marine Science, and Andrew Negri, Australian Institute of Marine Science

During the late spring, corals on the Great Barrier Reef release little balls that float to the ocean surface in a slow motion upside-down snowstorm.

These beautiful events are studied avidly by scientists: the tiny bundles will become young corals, and unlocking their secrets is vital to the continuing life of our coral reefs.


Read more: Newly discovered hermit crab species lives in ‘walking corals’


The first major mass spawning of 2017 unfolded last week following the early November full moon, with another spawning event predicted for December.

https://giphy.com/embed/l2QEeZl0oICDd4eqI

Mass spawning after the full moon

Coral species have a varied sex life. The majority of species are simultaneously male and female (hermaphrodites) and typically pack both eggs and sperm (gametes) into tight, buoyant bundles that are released after dark with remarkable synchronisation. The bundles float to the surface and open, allowing the eggs meet compatible sperm.

Less commonly, some coral species have separate sexes, and a few species even release asexually produced clones of themselves. For all species with sexual reproduction fertilised eggs develop into mobile larvae that settle on the sea floor and become polyps: the beginning of a new coral colony on the reef.

Mass spawnings are spectacular events, in which dozens of coral species release their gametes at specific times. Sometimes more than 100 species spawn on a single night, or over a few successive nights.


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


This iconic celebration of sex on the reef was first described in the central Great Barrier Reef in 1984 by a group of early-career scientists. The discovery earned them a prestigious Australian Museum Eureka Award for Environmental Research in 1992.

The precise timing of this seasonal phenomenon is linked to seawater temperature, lunar phases, and other factors such as the daily cycle of light and dark. Mass coral spawning is the dominant reproductive mode for corals on the Great Barrier Reef, and has also been recorded on reefs around the world.

https://giphy.com/embed/3o6fJd19E49uAPpkw8

The release of egg and sperm bundles is the culmination of many months of development. In years when the full moon falls early in October and November, many colonies are not quite ready and delay spawning for another lunar cycle. That’s why this year will see some action in November and another mass spawning event after the December full moon.

An important date in the scientific calendar

Spawning can be replicated in aquarium settings, which provide unique opportunities to researchers. All three of us work in the Australian Institute of Marine Science’s (AIMS) unique Sea Simulator, where large numbers of coral larvae are produced for scientific experiments.

Scientists from the Institute and around the world work through the spawning nights to collect gamete bundles, separate sperm and fertilise the eggs, then rear millimeter-long larvae and juveniles. Many experiments continue for days, weeks and even years to address critical knowledge gaps in how corals respond to and recover from stress.

New tools for coral reef management

The extensive coral death in the northern Great Barrier Reef following back-to-back bleaching events in 2016 and 2017 highlights the impacts of rapidly changing ocean conditions. AIMS scientists focus on developing ways to help coral adapt and restore damaged reefs.

Corals reefs are at a crossroads, but there is still hope. Experiments during this year’s spawning season will test whether surviving corals from recent bleaching events are naturally adapted to warmer reef temperatures, and if they produce more heat-tolerant young.


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


This knowledge underpins the development of active reef management tools such as assisted gene flow.

The huge Sea Simulator lets researchers carefully test how corals respond to stress.
Australian Institute of Marine Science, Author provided

Assisted gene flow involves moving heat-tolerant corals (or their young) to reefs that are warming. This technique proposes to improve the overall heat tolerance of local coral populations, to help the buffer the reef against future bleaching events caused by warmer than normal water temperatures.

More local threats to corals include poor water quality and pollution from coastal development. The early stages of a coral’s life are very sensitive to exposure to pesticides, oil spills and sediments from dredging.

Carefully controlled experiments with aquarium-reared coral larvae provide insights into the role of these local pressures on the rate of recovery and replenishment following large-scale disturbances.

The present reality for coral reefs is one of increasing strain from climate change, cyclones, crown-of-thorns starfish predation, and declining water quality. The ability of coral reef ecosystems to recover from these challenges relies on the success of mass coral spawning both on the reef and advances in the laboratory to generate new options to enhance reef resilience.

The ConversationExploring reef restoration and adaptation needs to go hand-in-hand with ongoing (and increasing) efforts in conventional management, such as climate change mitigation, regional management of water quality and control of crown-of-thorns starfish.

Line K Bay, Senior Research Scientist and Team Leader, Australian Institute of Marine Science; Andrew Heyward, Principal Research Scientist, Exploring Marine Biodiversity, Australian Institute of Marine Science, and Andrew Negri, Principal Research Scientist, Australian Institute of Marine Science

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

Don’t give up on Pacific Island nations yet


Jon Barnett, University of Melbourne

Fiji’s presidency of this year’s United Nations climate summit has put a renewed focus on the future of low-lying Pacific Islands. And while we should not ignore the plight of these nations, it is just as damaging to assume that their fate is already sealed.

Many people in Australia consider island nations such as Kiribati, Tuvalu and the Marshall Islands to be almost synonymous with impending climate catastrophe. After returning from Papua New Guinea in 2015, federal immigration minister Peter Dutton infamously joked that “time doesn’t mean anything when you’re about to have water lapping at your door”.

If influential and everyday Australians, and the rest of the world, hold the view that Pacific Island nations are doomed to succumb to climate change, the danger is that this will become a self-fulfilling prophecy.


Read more: Australia doesn’t ‘get’ the environmental challenges faced by Pacific Islanders


When we deny the possibility of a future for low-lying small islands, we are
admitting defeat. This in turn undermines the impetus to reduce greenhouse gas emissions and find ways to help communities carry on living in their island homes. It leaves us unable to discuss any options besides palliative responses for climate refugees.

There are other consequences of this pessimistic framing of islands. It may
undermine efforts to sustainably manage environments, because a finite future is
anathema to the sustaining resources in perpetuity. It can also manifest itself in harmful local narratives of denial or self-blame. And it can lead to climate change being blamed for environmental impacts that arise from local practices, which then remain unchanged.

We would do well to listen instead to what the leaders of low-lying island nations are saying, such as Tuvalu’s Prime Minister Enele Sopoaga, who told the 2013 Warsaw climate summit:

… some have suggested that the people of Tuvalu can move elsewhere. Let
me say in direct terms. We do not want to move. Such suggestions are
offensive to the people of Tuvalu. Our lives and culture are based on our
continued existence on the islands of Tuvalu. We will survive.

Those sentiments were echoed by the late Tony de Brum, former foreign minister of the Marshall Islands and described as the “voice of the Pacific Islands on climate change”, who said in 2015:

Displacement is not an option we relish or cherish and we will not operate on that basis. We will operate on the basis that we can in fact help to prevent this from happening.

Determined to survive

These leaders are determined for good reasons. Small islands are likely to respond in a host of different ways to climate change, depending on their geology, local wave patterns, regional differences in sea-level rise, and how their corals, mangroves and other wildlife respond to changing temperatures and weather patterns.

Evidence suggests that even seemingly very similar island types may respond very differently to one another. In many cases it is too early to say for sure that climate change will make a particular island uninhabitable.

But perhaps even more important in the future of low-lying small islands is the
way people adapt to climate change. There are all sorts of ways in which people can adapt their environments to changing conditions. Indeed, when the first migrants arrived in the low-lying atolls of Micronesia more than 3,000 years ago they found sand islands with no surface water and little soil, and settled them with only what they had in their small boats. Modern technologies and engineering systems can transform islands even more substantially, so that people can still live meaningful lives on them under changed climate conditions.

Adapting islands to climate change will not be easy. It will involve changes in where and how things are built, what people eat, how they get their water and energy, and what their islands look like.

It will also involve changes in institutions that are fundamental to island
societies, such as those concerned with land and marine tenure. But it can be done, with ingenuity, careful and long-term planning, technology transfer, and
meaningful partnerships between governments and international agencies.

Failure so far

Frustratingly, however, the international community is so far failing island states when it comes to this crucial adaptation. Despite their acute vulnerability having been recognised for at least 30 years, low-lying atoll countries such as Kiribati, the Marshall Islands and Tuvalu are attracting only low or moderate amounts of international adaptation funding. This is mostly as part of larger regional projects, and often focused on building capacity rather than implementing actual changes.

It is we who have failed to reduce greenhouse gas emissions and to help low-lying islands adapt, and it is we who cannot imagine any long-term future for them. It seems all we can do is talk about loss, migration, and waves of climate refugees. Having let them down twice, this defeatist thinking risks denying them an independent future for a third time. This is environmental neo-colonialism.


Read more: Islands lost to the waves: how rising seas washed away part of Micronesia’s 19th-century history


The international community has a moral responsibility to deliver a
comprehensive strategy to minimise the risks climate change poses to remote
low-lying islands. People living on these islands have a legal and moral right to lead dignified lives in their homelands, free from the interference of climate impacts. People who live in affluent countries high above sea level have several responsibilities here.

First, as most of us agree, we should reduce our greenhouse gas emissions. We have some control over that through how we consume, invest, vote and travel. Second, we should insist that our governments do more to help low-lying states to adapt to climate change. It is our pollution, after all. And we should argue for a reversal in our declining aid budgets.

The ConversationAnd finally, and perhaps most importantly, we should all stop talking down the future of low-lying small islands, because all this does is hasten their demise.

Jon Barnett, Professor, School of Geography, University of Melbourne

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

Did they mean to do that? Accident and intent in an octopuses’ garden



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A gloomy octopus perched above a bed of discarded scallop shells.
Peter Godfrey-Smith , Author provided

Martin Hing, University of Wollongong and Peter Godfrey-Smith, University of Sydney

We recently published a scientific report of octopuses living together in unusual numbers at a site on the south coast of New South Wales.

Then things got a little out of hand.


Read more: Octopuses invade Welsh beach – here are the scientific theories why


Gloomy octopus

The gloomy octopus, named for large eyes that can give the animal a doleful appearance, is the most common local octopus in NSW waters. Octopus tetricus, to use its scientific name, has usually been thought of as a solitary animal, and that has been the stereotype associated with most octopus species for many years.

The recent discovery of a site in Jervis Bay, Australia where these octopuses gather in quite high numbers is challenging that perception, and revealing some striking behaviours.

The site consists of three rocky outcrops, around which octopuses have built up an extensive bed of discarded scallop shells, mixed with some human debris.

A gloomy octopus swims over scattered scallop shells.
Peter Godfrey-Smith, Author provided

We think there is a process of “positive feedback” operating at the site. As scallops are brought back to the site to eat, the discarded shells provide material for additional octopuses to dig burrows. The shells line and stabilise the shaft-like dens. When the site was discovered in 2016, a total of 15 octopuses were present, along with several unoccupied dens.

This is the second site of its kind discovered. The first, reported in 2012, seems to have been formed around a discarded object, now very encrusted, of human origin.

The second site, which is entirely “natural,” shows that the same gathering of octopuses can occur without a “seeding” of the process by a human artefact.

At both sites, octopuses engage in quite complicated interactions – they produce displays, probe each other with their arms, and often try to evict other octopuses from their dens.

Other individuals of this species probably do live more solitary lives – when observed around Sydney, for example, they are almost always alone. This suggests that the octopuses have an ability to individually adapt their behaviour according to their circumstances.

Underwater city?

In September 2017, our scientific report of the second site was published, written with our colleagues David Scheel, Stephanie Chancellor, Stefan Linquist, and Matt Lawrence.

This paper received a good deal of media attention, with initial stories fairly accurate. But they seem to have started a self-sustaining process of their own, especially as a couple of early reports used the term “city” in their title. For example: “Scientists discover an underwater city full of gloomy octopuses.”

Gloomy octopus on the move.
Peter Godfrey-Smith, Author provided

This was probably influenced by the nickname chosen for the site, “Octlantis,” though our article did not talk about “cities” or anything similar. Soon the authors were fielding interview requests from around the world, wanting more details of the hidden octopus city and the lives of its denizens.

New online articles about the site seemed to build successively on exaggerations made in earlier articles, until our octopuses were reported as making “art” and building “fences”.

Octlantis is not a city, and no artworks, fences, or buildings have been made. In an era of rapid and unconstrained circulation of information around the internet, often with important political ramifications, the buzz around Octlantis is a reminder of how quickly rumours can arise and feed off each other, generating a literature that becomes less and less accurate at each step.

Accident versus intent

The Octlantis site does raise interesting questions about what the octopuses intend to do, and which effects of their actions are entirely inadvertent. Questions of “intent” are very difficult in work on animal behaviour, but we think some distinctions can be made – provisionally at least – in these terms.

Octopuses collect scallops for use as food. This requires them to make excursions from their den and find their way home. They bring the scallops home to eat, we assume, because it is safer than eating in the open. They also dig dens in the shell bed, and sometimes arrange shells and other objects around the edge of their den.

It seems quite likely to us that the collection of scallops and the building and maintenance of dens are all intentional behaviours (in a low-key sense of that term).

Why so gloomy, octopus?
Peter Godfrey-Smith, Author provided

Dens are sometimes maintained with some care, and octopuses will expel debris either by carrying it away, or with use of their jet propulsion mechanism, the “siphon.” But this does not imply that octopuses have any inkling that when they bring scallops back to the site, they are improving the den-building possibilities for themselves or others. Those effects may be entirely inadvertent.

Work is continuing on these animals and their unusual homes. One interesting question is whether other octopus species behave like this in some circumstances.

Another is why we observe groups of gloomy octopuses at these particular sites, and not in other areas where a solid object has been placed on the sea floor in what looks like similar circumstances.

The ConversationHow many octopuses’ gardens are out there, waiting to be discovered?

Martin Hing, PhD Researcher in marine and behavioural ecology, University of Wollongong and Peter Godfrey-Smith, Professor of History and Philosophy of Science, University of Sydney

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

Citizen scientist scuba divers shed light on the impact of warming oceans on marine life



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A volunteer diver surveys marine life at Lord Howe Island.
Rick Stuart-Smith/Reef Life Survey, Author provided

Madeleine De Gabriele, The Conversation

Rising ocean temperatures may result in worldwide change for shallow reef ecosystems, according to research published yesterday in Science Advances.

The study, based on thousands of surveys carried out by volunteer scuba divers, gives new insights into the relationship of fish numbers to water temperatures – suggesting that warmer oceans may drive fish to significantly expand their habitat, displacing other sea creatures.

Citizen science

The study draws from Reef Life Survey, a 10-year citizen science project that trains volunteer scuba divers to survey marine plants and animals. Over the past ten years, more than 200 divers have surveyed 2,406 ocean sites in 44 countries, creating a uniquely comprehensive data set on ocean life.

Reef Life Survey takes volunteers on surveying expeditions at hard-to-reach coral reefs around the world.
Rick Stuart-Smith/Reef Life Survey, Author provided

Lead author Professor Graham Edgar, who founded Reef Life Survey, said the unprecedented scope of their survey allowed them to investigate global patterns in marine life. The abundance of life in warm regions (such as tropical rainforests and coral reefs) has long intrigued naturalists. At least 30 theories have been put forward, but most studies have been based on relatively limited surveys restricted to a single continent or group of species.

By tapping into the recreational scuba diving community, Reef Life Survey has vastly increased the amount of information researchers have to work with. Professor Edgar and his colleagues provide one-on-one training to volunteers, teaching them how to carry out comprehensive scans of plants and animals in specific areas.

Dr Adriana Vergés, a researcher at the University of New South Wales specialising in the impact of climate change on ocean ecosystems, said that the Reef Life Survey has already substantially improved our understanding of the marine environment.

“For example, Reef Life Survey data has greatly contributed to our understanding of the factors that determine the effectiveness of effectiveness of marine-protected areas worldwide. The team have made all their data publicly available and more and more research is increasingly making use of it to answer research questions,” she said.

Some of the divers have been working with Reef Life Survey for a decade, although others participate when they can. One volunteer, according to Professor Edgar, was so inspired by the project that he began a doctorate in marine biology (he graduated this year).

There’s a strong link between fish numbers and water warmth, which means warming oceans are likely to change global fish distribution.
Rick Stuart-Smith/Reef Life Survey, Author provided

Warming oceans means fish on the move

One of the important insights delivered by the Reef Life Survey datatbase is the relationship between water temperature and the ratio of fish to invertebrates in an ecosystem. Essentially, the warmer the water, the more fish. Conversely, colder waters contain more invertebrates like lobster, crabs and shrimp.

Professor Stewart Frusher, director of the Centre for Marine Socioecology at the University of Tasmania (and a former colleague of Professor Edgar) told The Conversation that he believes we will see wide-scale changes in fish distribution as climate change warms the oceans.

“Species are moving into either deeper water or towards the poles. We also know that not all species are moving at the same rate, and thus new mixtures of ecosystems will occur, with the fast-moving species of one ecosystem mixing with the slower moving of another,” he said.

As species migrate or expand into newly warmed waters, according to Professor Frusher, they will compete with and prey on the species already living in that area. And while it’s uncertain exactly how disruptive this will be, we do know that small ecosystem changes can rapidly lead to larger-scale impacts.

In order to predict and manage these global changes, scientists need reliable and detailed world-wide data. Professor Frusher said that, with research funding declining, scientists do not have the resources to monitor at the scales required.

The Conversation“Well-developed citizen science programs fill an important niche for improving our understanding of how the earth is responding to change,” he said.

Madeleine De Gabriele, Deputy Editor: Energy + Environment, The Conversation

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