Indonesia and Australia are sleeping ocean superpowers


Ove Hoegh-Guldberg, The University of Queensland and Jamaluddin Jompa, Universitas Hasanuddin

In many ways, Australia and Indonesia represent ocean superpowers. The two neighbouring countries share huge marine resources and opportunities. At the same time both face increasing challenges to their oceans and coastal regions brought about by climate change and over-exploitation.

Recently, marine scientists from Australia and Indonesia identified possible areas of collaboration for their countries to solve these challenges.

The scientists came together at the inaugural Australia Indonesia Science Symposium organised by the Australian and Indonesian scientific academies. We were conveners for the two-day discussion between the Australian and Indonesian marine experts.

The scientists highlighted at least eight potential areas of collaboration on marine science and climate change:

  1. Scientists from both countries believe it’s important for Australia and Indonesia to work together to understand the impact of climate change on marine resources, and to create solutions. Climate change is causing rising sea levels and surface temperatures as well as ocean acidification. These have resulted in the bleaching of corals and mortality that affect livelihoods in both countries. Both scientific communities urge their governments to do more to rapidly reduce greenhouse gases.

  2. They pointed out that Australia and Indonesia should look into developing a strategy to reduce CO₂ and other emissions by maximising their coastal ecosystems and oceans as carbon sinks.

  3. The scientists recommended the two countries explore ways to increase cooperation and knowledge sharing in new technologies for the rapid monitoring of key marine resources. Many breakthroughs in technologies, such as image recognition, neural networks and machine learning, are set to rapidly reduce the time and costs of detailed reef monitoring.

  4. The two scientific communities also suggested the countries work together to advance the sciences to better manage migratory species such as turtles, sharks and other megafauna.

  5. They recommended a holistic approach to developing coastal fisheries. These fisheries require the development of whole-of-system thinking, with integrated management/governance that recognises the multiple uses and activities across space and time.

  6. They noted that development of national parks has been successful to a substantial extent in both countries. But more work must be done in both countries. Baseline datasets need to be developed in order to detect and respond to present and future impacts.

  7. The scientists see a need for Indonesia and Australia to develop greater cooperation on research, innovation and business development. The links between science and innovation and the blue economy need to be strengthened and reinforced.

  8. They identified a need and interest to develop a regional partnership to collaborate on problem solving in the ocean space and to develop databases that readily available to multiple cultural and language groups.

Why is this important?

Both Australia and Indonesia are heavily dependent on their extensive coastal regions and oceans for their food, income and well-being. The ocean holds enormous economic potential, which runs into billions of dollars each year.

Australia’s ocean spans over 13 million square kilometres – an area twice that of Australia’s landmass. Indonesia’s ocean stretches across almost 2 million square kilometres and the country is endowed with one of the longest coastlines of the world – almost 100,000km long!

An estimated 70% of Indonesia’s population, or around 180 million people, lives on this coastline. Similarly, 85% of Australia’s population lives within 50km of the coast.

But marine ecosystems of both countries are facing threats of over-exploitation and destruction.

Pollution from chemicals and plastics has begun to choke entire coastlines, destroying ecosystems and opportunity. At the same time, ocean ecosystems such as coral reefs, kelp forests and mangroves are disappearing at rates up to 2% per year from many coastal areas.

Most fisheries are under-performing. According to the FAO, 80% of the fish stocks are fully exploited or are collapsing. That is, we are getting much less than the sustainable yield should give us.

On top of this, ocean ecosystems and fisheries are severely threatened by climate change – through ocean warming and acidification. These impacts – from the deepest sea to our coasts – are threatening to foreclose on our future ocean wealth and opportunity.

The blue economy

The World Wildlife Fund recently estimated the asset value of the ocean to be US$24 trillion – which if it were a country would be the seventh-largest economy on the planet. This oceanic “wealth” fund delivers US$2.5 trillion in benefits to humanity each year – an economic activity associated with the marine economy that is growing three times faster than Australia’s GDP.

Increasingly, countries and businesses are turning to the ocean to generate novel industries and opportunities for food and income. Termed the “blue economy”, there is increasing focus on better using ocean resources to feed our hungry world.

By 2050 the world’s population will have added 3 billion people and will reach 9 billion. To feed those extra 3 billion people the Food and Agriculture Organisation has indicated that food production must increase by 70%.

The FAO has said that 80% of the required production increases will have to come from increases in crop yields, with only 20% coming from new farmlands.

But the stark reality is that the rate of growth in yields of the major cereal crops has been steadily declining – from about 3.2% per year in 1960 to 1.5% today. Consequently, we must find another alternative or risk ecological disaster as we turn more and more parts of the world’s crucial ecosystems into food production systems.

And it is much more than a matter of simply finding more food.

For industries, such as tourism, new fisheries, energy production and the development of new pharmaceuticals, the blue economy represents an enormous untapped potential.

Tackling the future as Marine Team Indonesia and Australia

It is critical to strike a balance between harvesting the economic potential of our ocean and safeguarding its longer-term health and well-being.

Unfortunately, despite the economic value of these opportunities, the marine resources of Australia and Indonesia are at serious risk of being degraded before we develop these opportunities.

There is a great opportunity and imperative for Australia and Indonesia to join forces to solve these critical challenges.

But to solve the problems, we need greater knowledge about our ocean wealth. We also need to build the capacity to understand and sensibly exploit these ocean resources.

All this means more people and infrastructure. We also need to promote greater regional knowledge and regional information exchange. We need to come together much more regularly to swap ideas and develop new solutions and approaches.

And if we do, then the power of our respective oceans will be unleashed for the greater good.

The Conversation

Ove Hoegh-Guldberg, Director, Global Change Institute, The University of Queensland and Jamaluddin Jompa, Professor and Dean of Marine Science and Fisheries, Universitas Hasanuddin

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

Changes to Australia’s marine reserves leave our oceans unprotected


Jessica Meeuwig, University of Western Australia; Craig Johnson, University of Tasmania; David Booth, University of Technology Sydney, and Ove Hoegh-Guldberg, The University of Queensland

Ocean health relies on a strong backbone of protection and management. Marine reserves can be part of the solution, but only if they’re constructed in the right way. Recent recommendations on Australia’s marine reserves would leave more ocean unprotected.

Marine reserves are a mix of multiple-use zones that allow activities such as mining and fishing, and highly-protected zones called marine national parks that are free of extractive activities. These marine national parks are the gold standard for protecting our oceans. Globally, less than 1% of the world’s oceans are fully protected in no-take marine national parks or their equivalents.

Australia is currently deciding how much of its ocean territory it will place in marine national parks and where. To this end, the government recently released its commissioned review of Australia’s Commonwealth Marine Reserve Network.

Such a review is welcome as Australia has yet to provide comprehensive, adequate and representative protection for its oceans. This is despite the general recognition within the Australian community that economic growth depends on a healthy and properly functioning environment.

Marine national parks play a fundamental role in contributing to ocean ecosystem function and provide a means to assess the health of areas outside of these zones that are open to greater use by humans.

This understanding of the interdependence of how we protect and sustainably use our oceans is, unfortunately, largely missing from the review’s recommendations.

The gold standard

In early 2016 the Ocean Science Council of Australia (OSCA) prepared a scientific analysis aimed at helping define what Australia’s marine reserves should deliver.

Based on hundreds of peer-reviewed publications and myriad international consensus statements from researchers on the need for strong ocean protection, the Council concluded that science-based decisions and actions should:

(1) Prevent fishing, mining and other extractive activities on at least 30% of each marine habitat, according to the international standard for ocean protection to deliver protection of both biodiversity and ecosystem services

(2) Improve representation of marine national parks in bioregions (regions of the ocean defined by particular species and climate) and key ecological features (such as the continental shelf and offshore reefs) that were already under-represented in the 2012 marine reserve plans

(3) Build and maintain large, contiguous, highly-protected marine national parks in regions such as the Coral Sea

(4) Quantify the benefits of Australia’s marine reserves so as to make their value to Australia clearer.

We need to monitor and study our ocean ecosystems to understand how they work.
David Booth, Author provided

What the review says

The government review reflects science and community concerns in some respects, recommending for instance that more bioregions have at least one marine national park. This review also recommends more protection for some important coral reefs and there is an expansion of protection from mining in some areas.

Most importantly, the review recognises the fundamental role of highly-protected marine national park zones in the conservation of species and ecosystems. As a corollary of this, the review also recognises that “partial protection” zones within reserves are primarily used to address narrow sector-based concerns such as fishing, and result in reduced conservation outcomes (as reviewed here and here).

It requires explanation therefore that the review mostly fails to recommend zoning changes consistent with its own findings on the science. In comparison with the 2013 recommended zoning, the review’s recommended zoning would:

(1) Remove a total of 127,000 square kilometres of marine national park from the overall network, an area 1.9 times the size of Tasmania, with a net loss of 76,000 sq km

(2) Reduce by 25% the contiguous Coral Sea marine national park

Changes to Coral Sea marine national park proposed by review. Map generated from shape files provided by the Department of the Environment.

(3) Demote 18 areas from marine national park zones to varying forms of partial protection

(4) Shift the location of some marine national parks from the continental shelf to offshore areas as a way of maintaining cover but further eroding representation and indeed reducing protection on the shelf where it is most needed.

Overall, the review’s recommendations would see only approximately 13% of Australia’s Exclusive Economic Zone protected in marine national parks. This falls well below the recommended international standard of at least 30% of habitats being under high protection, or indeed higher levels as recently determined.

Smoke and mirrors

The recommendations in the review are tainted by a feeling of smoke and mirrors. While some of the review’s authors suggest that their recommendations would increase protection, there would indeed be a net loss of highly-protected zones should these recommendations be adopted by the government.

Under the review’s recommendations, Australia would do a great job of protecting the deep water abyss, but achieve little to protect ocean wildlife on the continental shelf where human pressures are highest. This out-of-sight-out-of-mind approach does not address the principles of marine conservation and also departs from recommendations from the research community.

Australian marine national parks are too-often relegated to residual areas of relatively little conservation value simply because these areas are of little value to commercial interests.

The significant erosion of protection in the Coral Sea is further evidence of this failure. Much of the erosion of this important reserve reflects a shift from full protection to partial protection in order to open up more ocean to tuna fishing.

The 25% reduction in large marine national park would increase tuna catch and value by 8-10% across the fishery, worth a mere A$26,376 to individual tuna fishers. This recommendation fails both the science and the economic test.

Where to from here?

The changes recommended by the review in many cases appear to prioritise economic benefits, no matter how trivial, over conservation. This is despite conservation being the core reason behind the marine reserves.

This stands in stark contrast to international moves towards protection of large areas of the ocean as a response to ongoing declines in ocean health.

Key examples of such large-scale protection are US President Barack Obama’s recent expansion of the Papahānaumokuākea Marine National Monument over the North West Hawaiian Islands and New Zealand Prime Minister John Key’s declaration of the Kermadec Marine Sanctuary in New Zealand’s waters.

Australia still has a major opportunity to protect and secure its marine ecosystems and make a significant contribution to global ocean conservation. At the same time we can develop important economic activities such as fishing and mining. Large and well-managed areas are going to become more important, not less, as climate change intensifies.

This will require the federal government to acknowledge and build on the global body of science and create a backbone of representative marine national parks. This will include retention of the Coral Sea’s high level protection and resisting the temptation to shift of marine national parks offshore. At a time of great environmental change, these moves are not just important, but urgent.

This is a contribution from the Ocean Science Council of Australia.

The Conversation

Jessica Meeuwig, Professor & Director, Centre for Marine Futures, University of Western Australia; Craig Johnson, Professor, University of Tasmania; David Booth, Professor of Marine Ecology, University of Technology Sydney, and Ove Hoegh-Guldberg, Director, Global Change Institute, The University of Queensland

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

The silencing of the seas: how our oceans are going quiet


Ivan Nagelkerken, University of Adelaide; Sean Connell, University of Adelaide, and Tullio Rossi, University of Adelaide

Despite appearances, the oceans are far from silent places. If you dunk your head underwater you’ll hear a cacophony of sounds from wildlife great and small, crashing waves, and even rain. And it’s louder still for creatures attuned to these sounds.

However, humans are changing these ocean soundscapes. Our recent research showed that changes caused by people, from ocean acidification to pollution, are silencing the seas’ natural noises. (We’re also filling the oceans with human noise).

This is bad news for the species that depend on these noises to find their way.

Ocean soundscapes

All over the world you can hear a lively crackling sound made by thousands of snapping shrimp that live along coastlines.

These common shrimp, often referred to as pistol shrimp, have a large claw that they can close with such force that a cavitation bubble is formed. As this bubble implodes on itself a loud snap is created – like a pistol shot – which can be heard over long distances.

In fact, snapping shrimp are the loudest marine invertebrates, and second only to the noisest marine animals, which are sperm whales! Snapping shrimp are found all over the world, including in coral reefs, kelp forests, seagrass beds and mangroves.

Other types of animals create ocean noise too. Urchins and parrotfish make clearly audible chomping sounds as they scrape algae off rocks. Many fish are frequent and loud talkers and make an array of sounds such as chirps, burps, whistles, knocks and so on. They use these to mark out their territory, during fights and to locate mates.

These biological sounds, together with those from rain, crashing waves and seismic activities, form the so-called underwater soundscape.

Learn more about marine soundscapes watching this video.

Sounds that are emitted from temperate and tropical reefs are loud and quite constant. As such these sounds form a reliable source of information for animals, particularly for navigation.

Most animals in the sea let go of their fertilised eggs without providing any parental care. As these eggs hatch, small babies (larvae) are dispersed by ocean currents. Growing up away from coastal areas provides a safer place with fewer predators.

However, after growing for a few weeks or months in the open ocean, it is time for these young animals to return to the coast to find a home. How do they find their way in the vast and uniform open ocean? Sounds and odours from coastal habitats are key cues that allow marine animals to find their new homes and replenish adult populations.

Going quiet

Humans are increasingly dominating the physical and chemical environment. We are altering the carbon cycle through the burning of fossil fuels and the nitrogen cycle by extracting vast amounts of nitrogen for food production and releasing it as waste. Large amounts of this carbon and nitrogen liberation end up in the ocean.

About one-third of the carbon dioxide that humans emit into the atmosphere dissolves in the ocean, leading to increased seawater acidity (or ocean acidification). This is an obvious problem for animals that produce a calcium carbonate shell or skeleton (such as corals, some plankton, and snails). Remarkably, ocean acidification also alters the behaviour of many animals by messing up their brain functioning.

Earlier studies (see also here) have shown that ocean acidification can change the response of fish larvae to settlement habitat sounds by deterring them rather than attracting them.

Learn more about the effects of ocean acidification on fish behaviour watching this animation video.

Two of our recent studies (see also here) showed that ocean acidification not only affects sound reception, but also the sounds that ocean ecosystems produce. If we don’t reduce greenhouse gas emissions, rocky reefs could be much quieter in 2100 than now. And snapping shrimps are the reason.

Coastal discharge of nutrients from sewage plants and catchment runoff also degrades kelp forests and seagrass beds. These coasts are more silent than their healthy counterparts.

In many parts of the world, kelp forests, seagrass beds and coral reefs have been replaced by carpets of turf-forming or mat-forming algae. These weedy types of algae have much lower diversity of species and provide less shelter and feeding opportunities for shrimps and other noisy animals.

Degraded habitat means fewer animals, which means less noise. For larvae that use sound as a navigational cue, this means that fewer larvae will be able to successfully locate their home. And fewer returning larvae means less replenishment of fish stocks.

The effects of ocean acidification on fish orientation and soundscapes.
Dr Tullio Rossi

Options for restoration

Climate change and ocean acidification act at global scales and are difficult to stop in the short term. In contrast, nutrient pollution is a local stressor, which makes it more manageable.

Various options exist for local communities to reduce nutrient pollution of coastal areas. These include improved sewage treatment, restoration of coastal vegetation (such as mangroves) and swamps that extract sediment and nutrients from stormwater runoff, and decreasing the use of rivers as outlets for polluted waters.

Reducing the impacts of nutrient pollution on coastal ecosystems makes these systems more robust and provides them with increased resilience to cope with the impacts of ocean warming and acidification.

The Conversation

Ivan Nagelkerken, Associate Professor, Marine Biology, University of Adelaide; Sean Connell, Professor, University of Adelaide, and Tullio Rossi, PhD student, University of Adelaide

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

Ocean acidification is already harming the Great Barrier Reef’s growth


Kennedy Wolfe, University of Sydney and Maria Byrne, University of Sydney

A new experiment on the Great Barrier Reef has shown, for the first time, that ocean acidification is already harming the growth of coral reefs in their natural setting.

As our research published in Nature today shows, the reduction in seawater pH – caused by carbon dioxide from human activities such as burning fossil fuels – is making it more difficult for corals to build and maintain their skeletons.

We and our colleagues, led by Rebecca Albright and Ken Calderia from the Carnegie Institution for Science in Stanford, California, carried out the first experimental manipulation of seawater chemistry in a natural coral reef ecosystem. Previous climate change studies on coral reefs have been done either in the laboratory or in closed-system tanks on the reef.

One Tree Island forms a naturally isolated lagoon where pH levels can be manipulated.
One Tree Island Research Station/University of Sydney/Nature

Coral reefs are particularly vulnerable to ocean acidification because calcium carbonate, the mineral building blocks of their skeletons, dissolves easily in acid. Below a certain pH, this dissolution is predicted to outweigh the accumulation of new calcium carbonate that allows reefs to grow and to recover from erosion processes such as storms.

Previous studies have shown large-scale declines in coral reefs over recent decades. Rates of reef calcification were 40% lower in 2008-09 than in 1975-76.

However, it was hard to pinpoint exactly how much of the decline was due to acidification, and how much was caused by other human-induced stresses such as ocean warming, pollution and overfishing. Understanding this is essential to predicting how coral reefs may fare in the face of continued global climate change.

The study used pink dye to track the movement of the experimental seawater.
Rebecca Albright/Nature

To answer this question, we manipulated the pH of seawater flowing over a reef flat at One Tree Island in the southern Great Barrier Reef. By adding sodium hydroxide (an alkali), we brought the reef’s pH closer to levels estimated for pre-industrial times, based on estimates of atmospheric carbon dioxide from that era. In doing so, we pushed the reef “back in time”, to find out how fast it would have been growing before human-induced acidification began.

It was clear from our results that reef calcification was around 7% higher under pre-industrial conditions than those experienced today.

Most other ocean acidification experiments manipulate seawater conditions based on the low pH levels predicted for coming decades, to understand the potential effects of future ocean conditions. But we have shown that present-day conditions are already taking their toll on corals.

As Albright explains:

Our work provides the first strong evidence from experiments on a natural ecosystem that ocean acidification is already causing reefs to grow more slowly than they did 100 years ago. Ocean acidification is already taking its toll on coral reef communities. This is no longer a fear for the future; it is the reality of today.

With greenhouse gas emissions continuing to rise, our results suggest a bleak future for coral reefs over the coming decades, with reduced calcification and increased dissolution. This is particularly concerning in light of the major coral bleaching events observed globally over the past few years amid prolonged high sea surface temperatures. The mixed effects of ocean warming and acidification, as well as other human-induced and natural stressors, pose serious threats to the ecosystems we know today.

Increasing the alkalinity of ocean water around coral reefs has been proposed as a geoengineering measure to save shallow marine ecosystems. Our results suggest that this could be effective in isolated areas, but implementing such measures at large scales would be almost impossible.

As our colleague Ken Caldeira has pointed out, the only real and lasting solution is to make deep, rapid cuts in our carbon dioxide emissions. Otherwise the next century could be one without coral reefs.

Kennedy Wolfe will be online to answer questions about this research from 11.30 am to 12.30 pm AEDT on Thursday February 25. Leave your comments below.

The Conversation

Kennedy Wolfe, PhD Candidate, University of Sydney and Maria Byrne, Professor of Developmental & Marine Biology, University of Sydney

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

The Great Barrier Reef faces a mixed future in acidifying oceans


Mathieu Mongin, CSIRO; Andrew Lenton, CSIRO; Jennifer Skerratt, CSIRO, and Mark Baird, CSIRO

Those of us who have been fortunate enough to have travelled to spectacular coral reefs marvel at their colour and biodiversity.

At around 2,000 km long, the Great Barrier Reef is the largest coral reef system in the world. It includes 3,581 individual reefs and an immense lagoon. But the likelihood of future generations being able to enjoy the beauty of the Great Barrier Reef is dwindling, as it comes under increasing pressure from the degradation of water quality and climate change.

Warming water is one of the greatest threats facing the reef in the long term. But what about another consequence of rising carbon dioxide, ocean acidification?

When carbon dioxide dissolves in water it (slightly) increases the water’s acidity, or lowers its pH. This affects the ability of marine creatures such crustaceans, corals and coralline algae to build their skeletons. But exactly how it will affect the whole reef ecosystem is unknown.

In research published in Nature Communications, we mapped parts of the reef that are most exposed to ocean acidification. As you’d expect, there will be some regions more strongly affected than others, indicating where we might focus our efforts to preserve the reef.

Building skeletons

Conditions in the marine tropics are becoming less friendly for coral. Coral bleaching, cyclones, outbreaks of pest species and nutrient-impacted river run-off are now regular events that impact coral reef health.

What’s more, and perhaps more ominously, as the world’s oceans take up more carbon dioxide, it becomes harder for corals to secrete and maintain their calcium carbonate skeletons. While the exact response remains unknown, at some point thresholds will be reached at which dissolution exceeds calcification, leading to overall coral loss.

But ocean acidification doesn’t affect the whole reef equally. Corals change the chemistry of the seawater around them. In fact, corals are constantly building and dissolving their skeletons, taking up and releasing calcium carbonate into the water, thus increasing or lowering the pH.

The fine balance between these processes changes over the course of the day. Ocean circulation, as well as photosynthesis and respiration of other non-calcifying marine organisms, also determine the overall variability in pH of water above reefs, and therefore a coral’s ability to produce and maintain their structure.

While scientists have researched these effects on individual reefs, how do they play out on the thousands of reefs that make up the entire Great Barrier Reef?

To find the answer we used a new information system developed for the Great Barrier Reef. We found that some inshore reefs experience a lower pH now than is projected for offshore reefs in the future.

Which reefs are most threatened?

On the Great Barrier Reef, the ability for coral to build skeletons tends to decrease towards the coast. This is a consequence of the lower pH, and more nutrients, fresh water and sediment coming from the land.

GBR Coral reef’s exposure to global ocean acidification, green reefs have some protection, white are neutral and red are already exposed.
CSIRO

But details of a more complex picture emerged from the study, highlighting the interaction between the thousands of reefs.

The outer reefs generally have Coral Sea water flowing over them, and for a thin band, especially in the north, their ability to build skeletons is actually driven by large scale oceanographic processes. But as the outer reef corals build their skeletons, the water flowing off them has lowered pH (more acidic). Circulation carries this water onto parts of the inner reefs, changing the average pH above their corals.

In other words, good coral health in the outer reefs, especially in the northern and southern regions, creates less favourable conditions for the mid lagoon central reefs.

What can we do?

While atmospheric carbon dioxide concentrations are increasing, focus should shift to conserve parts of the Great Barrier Reef and its corals which can be achieved through changes in the way we manage the reef. The new map of pH on the Great Barrier Reef presents the exposure to ocean acidification on each of the 3,581 reefs, providing managers with the information they need to tailor management to individual reefs.

Thus we see the Great Barrier Reef is not a singular reef nor a physical barrier that prevents exchange between reefs; it is a mixture of thousands of productive reefs and shallow areas lying on a continental shelf with complex oceanic circulation.

We cannot treat the Great Barrier Reef as one entity. We cannot summarise the impact of global ocean acidification as one number, and we cannot have one management strategy (aside from cutting global carbon emissions) to protect it.

The Conversation

Mathieu Mongin, Biogeochemical Modeller, CSIRO; Andrew Lenton, Senior Research Scientist, CSIRO Oceans and Atmosphere Flagship, CSIRO; Jennifer Skerratt, Coastal and enivronmental modeller, CSIRO, and Mark Baird, Team leader, Coastal and Environmental Modelling, CSIRO

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

Ocean acidification causes young corals to develop deformed skeletons


Taryn Foster, University of Western Australia and Peta Clode, University of Western Australia

Coral reefs around the world are facing a whole spectrum of human-induced disturbances that are affecting their ability to grow, reproduce and survive. These range from local pressures such as overfishing and sedimentation, to global ones such as ocean acidification and warming. With the third global coral bleaching event underway, we now more than ever, need to understand how coral responds to these stressors.

Our new research, published in Science Advances, now shows that young corals develop deformed and porous skeletons when they grow in more acidified waters, potentially making it more difficult for them to establish themselves on the reef and survive to adulthood.

Juvenile corals

Corals vary in their responses to stress, not only between species and location, but also among different stages of their life cycle. Juvenile corals are extremely important to the health of a reef, as they help to replenish the reef’s coral population and also help it recover from severe disturbances such as bleaching and storms.

However, newly settled young corals are small (typically about 1 mm across) and therefore very vulnerable to things like overgrowth and predation. To survive into adulthood they need to grow quickly out of this vulnerable size class. To do that they need to build a robust skeleton that can maintain its structural integrity during growth.

Two major factors that affect coral skeletal growth are ocean temperature and carbon dioxide concentration. Both are on the rise as we continue to emit huge amounts of CO₂ into the atmosphere. Generally with adult corals, increased temperature and CO₂ both reduce growth rates. But this varies considerably depending on the species and the environmental conditions to which the coral has been exposed.

Much less is known about the impacts of these factors on juvenile corals. This is mainly because their small size makes them more difficult to study, and they are only usually around once a year during the annual coral spawn. The corals we studied spawn for just a couple of hours, on one night of the year, meaning that our study hinged on taking samples during a crucial one-hour window.

When collecting the samples, at Western Australia’s Basile Island in the Houtman Abrolhos archipelago in March 2013, we watched the adult spawners each night waiting to see if they would spawn and, when they did, we worked all night fertilising the eggs to collect our juvenile samples.

Having collected our elusive coral samples, we cultured and grew newly settled coral recruits under temperature and CO₂ conditions that are expected to occur by the end of the century if no action is taken to curb the current trajectory of CO₂ emissions.

We then used three-dimensional X-ray microscopy to look at how these conditions affect the structure of the skeleton. This technique involves taking many X-ray projection images of the sample (in this case around 3,200) and then reconstructing them into a 3D image.

A 3D X-ray microscopy image of a one-month-old coral skeleton.
Taryn Foster/Science Advances, Author provided

Deformed and porous skeletons

Corals grown under high-CO₂ conditions not only showed reduced skeletal growth overall, but developed a range of skeletal deformities.

These included reduced overall size, gaps, over- and under-sized structures, and in some cases, large sections of skeleton completely missing. We also saw deep pitting and fractures in the skeletons of corals grown under high CO₂, typical of skeletal dissolution and structural fragility.

Surprisingly, increased temperature did not have a negative impact on skeletal growth and for some measures even appeared to help to offset the negative impacts of high CO₂ – a response we think may be unique to sub-tropical juveniles.

Nevertheless, our study highlights the vulnerability of juvenile corals to ocean acidification.

Under the current CO₂ emissions trajectory, our findings indicate that young corals will not be able to effectively build their skeletons. This could have wider implications for coral reef health, because without healthy new recruits, reefs will not replenish and will be less able to bounce back from disturbances.

The effect of temperature in this study however, was both a surprising and welcome finding. There is a lot of variation even between species, but it is possible that subtropical organisms have more plasticity due to their natural exposure to a wider range of conditions. This could indicate that subtropical juveniles may have an unexpected edge when it comes to ocean warming.

The Conversation

Taryn Foster, PhD Candidate, School of Earth and Environment, University of Western Australia and Peta Clode, Associate Professor, University of Western Australia

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

Don’t go in the water: a world of pain awaits in Australia’s deep blue seas


Lisa-ann Gershwin, CSIRO

Australia’s reputation for deadly creatures of all kinds is known the world over. Tourists worry about it, and comedians have a field day with it. Here’s what Bill Bryson says in his book In a Sunburned Country:

[Australia] has more things that will kill you than anywhere else. Of the world’s ten most poisonous snakes, all are Australian. Five of its creatures – the funnel web spider, box jellyfish, blue-ringed octopus, paralysis tick and stonefish – are the most lethal of their type in the world.

Bryson certainly has a way with words. But, to be honest, he forgot a few things.

The long list

Australia has at least nine species of Irukandjis, a group of jellyfish so nasty that their drop-for-drop toxicity leaves the box jellyfish in the dust.

Impressive, considering the box jelly has long been considered the world’s most venomous animal. A massive sting from a box jelly kills in as little as two minutes; for other victims, it’s generally painful with some scarring, but that’s about it.

Irukandji, in contrast, with just an imperceptible brush of venom leaves almost no mark. But after about a half hour you develop Irukandji syndrome, a debilitating mix of nausea, vomiting, severe pain, difficulty breathing, drenching sweating and sense of impending doom. You get so sick that your biggest worry is that you’re not going to die!

And that’s just the beginning: up to a third of victims require life support and a quarter have ongoing complications, including permanent heart damage or neurological damage.

Bryson also forgot the blue bottles that sting some 25,000 to 45,000 people each year in Australia, at least one species of which causes Irukandji syndrome.

And he forgot the bullrout, which is kind of a brackish-water version of the stonefish – caution, they hang out at boat ramps and these suckers hurt.

And stingrays, which combine stabbing and venom into the one injury. And the cone snail, which looks mild-mannered, but can imperil your life with one stab of its lightning-fast barb.

Then there are sea urchins and stinging hydroids and venomous sponges, which will put you in a world of hurt. But nobody ever thinks to include them.

And the sea snakes: if you get one in your fishing net, or your dive equipment, or your hair, remember the old adage “don’t grab a snake by its tail”. Well, I’m not sure if that’s an adage or not, but it should be. In fact, “don’t grab a snake” would be better.

Bryson also forgot the world’s only venomous mammal, the platypus: males have a venomous spur on the back legs, and they seriously hurt. And my new favourite, the arrow worm. Yes, the arrow worm.

Granted, there aren’t any reported deaths from arrow worms, but they deserve respect. They look like a beansprout with fish fins, with a fish tail at one end and rows of big scary spines at the other, which they use to grasp their food. And they “bite” with tetrodotoxin – the same venom that makes fugu (the pufferfish delicacy) and blue ring octopus so lethal.

And swans. Bryson forgot swans. At least three people have reportedly been killed by swans. I’m just sayin’. (Good news: these are not the native Australian black swans).

But why?

Okay, venomous beansprouts, swans and fear of not dying aside, what is it with Australia’s dangerous creatures? The typical explanation for powerful venoms is subduing dinner or dealing quickly with danger, especially for delicate creatures or those that aren’t able to track prey for long distances.

But certainly the box jellyfish’s venom is overkill, while the Irukandji takes too long. What’s more, fish don’t appear to get Irukandji syndrome … although I’ve never been sure how to tell if a fish is sweating.

Similarly, the dinner-or-danger hypothesis doesn’t seem to hold true for stabbing fish wounds, such as those delivered by stonefish, bullrouts and stingrays. Certainly, the stabbing must be far more effective than all but the most instant venom effects.

But one must keep in mind that these creatures evolved their toxins long before Homo sapiens fossicked the tide pools or snorkelled the reefs. So although their venoms can harm us, this may just be coincidental.

A question that often arises is what effect climate change will have on these creatures or their venoms. Well, the answer is we really don’t know yet.

With regard to species, there will be winners and losers. Many of the venomous sea creatures are tropical, and many tropical species are expanding southward. To what extent this may put the more populated southerly areas at higher risk is still unclear.

One group, however, seems particularly poised to benefit: the jellyfishes. As warmer water stimulates their metabolism, they grow faster, eat more, breed more and live longer. Irukandjis and box jellyfish become more toxic as they mature, so getting there faster and staying there longer could have undesirable outcomes for sea users.

How, then, can we possibly navigate these dangers when curious sea snakes want to swim with us, duckbilled platypus, stones and beansprouts must be viewed with suspicion, blue is sounding like the new warning colour, invisible jellyfish will lay us flat, and even the swans, a symbol of romance, are scary?

Four tips for keeping safe

Rule 1: First and foremost, try to make it a rule never to touch an animal that isn’t a personal friend. This will prevent the vast majority of bite and sting injuries, and not just from sea creatures.

Rule 2: Do the stingray shuffle when moving in sandy water: drag your feet in such a way that you’re continuously kicking sand in front to where you’re about to step. This will scare most creatures away so that you don’t step on them.

Rule 3: Wear protective clothing (a full-body lycra suit, for instance) when swimming in areas where box jellyfish or Irukandjis may appear. If stung by box jellyfish or Irukandjis or unknown jellyfish in the tropics, douse with vinegar to neutralise undischarged stinging cells.

Rule 4: Don’t try to make friends with swans.

Finally, read the Australian Resuscitation Council website for the latest on prevention and first aid for bites and stings.

This article is part of our series Deadly Australia. Stay tuned for more pieces on the topic in the coming days.

The Conversation

Lisa-ann Gershwin, Research scientist, CSIRO

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