Their fate isn’t sealed: Pacific nations can survive climate change – if locals take the lead


Rachel Clissold, The University of Queensland; Annah Piggott-McKellar, University of Melbourne; Karen E McNamara, The University of Queensland; Patrick D. Nunn, University of the Sunshine Coast; Roselyn Kumar, University of the Sunshine Coast, and Ross Westoby, Griffith University

They contribute only 0.03% of global carbon emissions, but small island developing states, particularly in the Pacific, are at extreme risk to the threats of climate change.

Our study, published today in the journal Nature Climate Change, provides the first mega-assessment on the progress of community-based adaptation in four Pacific Island countries: the Federated States of Micronesia, Fiji, Kiribati and Vanuatu.




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Pacific Island nation communities have always been resilient, surviving on islands in the middle of oceans for more than 3,000 years. We can learn a lot from their adaptation methods, but climate change is an unprecedented challenge.

Effective adaptation is critical for ensuring Pacific Islanders continue living fulfilling lives in their homelands. For Australia’s part, we must ensure we’re supporting their diverse abilities and aspirations.

Short-sighted adaptation responses

Climate change brings wild, fierce and potentially more frequent hazards. In recent months, Cyclone Harold tore a strip through multiple Pacific countries, killing dozens of people, levelling homes and cutting communication lines. It may take Vanuatu a year to recover.

Expert commentary from 2019 highlighted that many adaptation responses in the Pacific have been short-sighted and, at times, even inadequate. The remains of failed seawalls, for example, litter the shorelines of many island countries, yet remain a popular adaptive solution. We cannot afford another few decades of this.




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International climate aid commitments from rich western countries barely scratch the surface of what’s needed, yet it’s likely funding will dry up for regions like the Pacific as governments scramble together money for their own countries’ escalating adaptation costs.

This includes Australia, that has long been, and continues to be, the leading donor to the region. Our government contributed about 40% of total aid between 2011 and 2017 and yet refuses to take meaningful action on climate change.

Understanding what successful adaptation should look like in developing island states is urgent to ensure existing funding creates the best outcomes.

Success stories

Our findings are based on community perspectives. We documented what factors lead to success and failure and what “best practice” might really look like.

We asked locals about the appropriateness, effectiveness, equity, impact and sustainability of the adaptation initiatives, and used this feedback to determine their success.




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The results were mixed. While our success stories illustrate what “best practice” involves, issues still emerged.

Our top two success stories centred on community efforts to protect local marine ecosystems in the Federated States of Micronesia and Vanuatu. Nearby communities rely on these ecosystems for food, income and for supporting cultural practice.

One initiative focused on establishing a marine park with protected areas while the other involved training in crown-of-thorns starfish control. As one person told us:

we think it’s great […] we see the results and know it’s our responsibility.

Initiatives that focus on both the community and the ecosystem support self-sufficiency, so the community can maintain the initiatives even after external bodies leave and funding ceases.

Pele Island, Vanuatu. Can you see coral in the water? The community initiative was aiming to protect this coral ecosystem from crown-of-thorns starfish.
Karen McNamara, Author provided

In these two instances, the “community” was expanded to the whole island and to anyone who utilised local ecosystems, such as fishers and tourism operators.

Through this, benefits were accessible to all: “all men, all women, all pikinini [children],” we were told.

Standing the test of time

In Vanuatu, the locals deemed two initiatives on raising climate change awareness as successful, with new scientific knowledge complementing traditional knowledge.

And in the Federated States of Micronesia, locals rated two initiatives on providing tanks for water security highly. This initiative addressed the communities’ primary concerns around clean water, but also had impact beyond merely climate-related vulnerabilities.

This was a relatively simple solution that also improved financial security and minimised pollution because people no longer needed to travel to other islands to buy bottled water.

Aniwa, Vanuatu. A communal building in the village has a noticeboard, put up as part of one of the climate-awareness raising initiatives.
Rachel Clissold, Author provided

But even among success stories, standing the test of time was a challenge.

For example, while these water security initiatives boosted short-term coping capacities, they weren’t flexible for coping with likely future changes in drought severity and duration.




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Pacific islands are not passive victims of climate change, but will need help


Adaptation needs better future planning, especially by those who understand local processes best: the community.

Listening to locals

For an adaptation initiative to be successful, our research found it must include:

  1. local approval and ownership

  2. shared access and benefit for community members

  3. integration of local context and livelihoods

  4. big picture thinking and forward planning.

To achieve these, practitioners and researchers need to rethink community-based adaptation as more than being simply “based” in communities where ideas are imposed on them, but rather as something they wholly lead.

Communities must acknowledge and build on their strengths and traditional values, and drive their own adaptation agendas – even if this means questioning well-intentioned foreign agencies.

Being good neighbours

Pacific Islands are not passive, helpless victims, but they’ll still need help to deal with climate change.

Pacific Island leaders need more than kind words from Australian leaders.




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Pacific Island nations will no longer stand for Australia’s inaction on climate change


Last year, Fijian prime minister, Frank Bainimarama, took to Facebook to remind Australia:

by working closely together, we can turn the tides in this battle – the most urgent crisis facing not only the Pacific, but the world.

Together, we can ensure that we are earthly stewards of Fiji, Australia, and the ocean that unites us.

Together, we can pass down a planet that our children are proud to inherit.The Conversation

Rachel Clissold, Researcher, The University of Queensland; Annah Piggott-McKellar, Postdoctoral research fellow, University of Melbourne; Karen E McNamara, Associate professor, The University of Queensland; Patrick D. Nunn, Professor of Geography, School of Social Sciences, University of the Sunshine Coast; Roselyn Kumar, , University of the Sunshine Coast, and Ross Westoby, Research Fellow, Griffith University

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

Climate change threatens Antarctic krill and the sea life that depends on it



Brett Wilks

Devi Veytia, University of Tasmania and Stuart Corney, University of Tasmania

The Southern Ocean circling Antarctica is one of Earth’s richest marine ecosystems. Its food webs support an abundance of life, from tiny micro-organisms to seals, penguins and several species of whales. But climate change is set to disrupt this delicate balance.

Antarctic krill – finger-sized, swarming crustaceans – might be small but they underpin the Southern Ocean’s food web. Our research published today suggests climate change will cause the ocean habitat supporting krill growth to move south. The habitat will also deteriorate in summer and autumn.

The ramifications will reverberate up the food chain, with implications for other Antarctic animals. This includes humpback whales that feed on krill at the end of their annual migration to the Southern Ocean.

Changes in krill habitat could affect species up the food chain including the humpback whale.
Mike Hutchings/AAP

What we found

Antarctic krill are one of the most abundant animal species in the world. About 500 million tonnes of Antarctic krill are estimated to exist in the Southern Ocean.

Antarctic krill play a critical role in the ocean’s food webs. But their survival depends on a delicate balance of food and temperature. Scientists are concerned at how climate change may affect their population and the broader marine ecosystem.

We wanted to project how climate change will affect the Southern Ocean’s krill “growth habitat” – essentially, ocean areas where krill can thrive in high numbers.

Krill growth depends largely on ocean temperature and the abundance of its main food source, phytoplankton (microscopic single-celled plants).




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Under a “business as usual” climate change scenario, future changes in ocean temperature and phytoplankton varied depending on the region and season.

In the mid-low latitudes, our projections showed temperatures warmed towards the limits krill can tolerate. For example, by 2100 the waters during summer around South Georgia island warmed by 1.8℃.

Warming water was often accompanied by decreases in phytoplankton; in the Bellingshausen Sea during summer a 1.7℃ rise halved the available phytoplankton.

However, phytoplankton increased closer to the continent in spring and summer – most dramatically by 175% in the Weddell Sea in spring.

Antarctic krill habitat will shift south under climate change.
Simon Payne, Australian Antarctic Division

Shifting habitat

Across all seasons, krill growth habitat remained relatively stable for 85% of the Southern Ocean. But important regional changes still occurred.

Krill growth habitat shifted south as suitable ocean temperatures contracted towards the poles. Combined with changes in phytoplankton distribution, growth habitat improved in spring but deteriorated in summer and autumn.




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This early end to the growth season could have profound consequences for krill populations. The krill life cycle is synchronised with the Southern Ocean’s dramatic seasonal cycles. Typically this allows krill to both maximise growth and reproduction and store reserves to survive the winter.

A shift in habitat timing could create a mismatch between these two cycles.

For example, female krill need access to plentiful food during the summer in order to spawn. Since larger females produce exponentially more eggs, a decline in summer growth habitat could result in smaller females and far less spawning success.

Antarctic predators including penguins rely on krill for survival.
Royal Navy

Why this matters

Krill’s significant role in the food chain means the impacts of these changes may play out through the entire ecosystem.

If krill shift south to follow their retreating habitat, less food would be available for predators on sub-Antarctic islands such as Antarctic fur seals, penguins and albatrosses for whom krill forms a significant portion of the diet.

In the past, years of low krill densities has coincided with declines in reproductive success for these species.

Shifts in krill habitat timing may also affect migratory predators. For example, each year humpback whales migrate from the tropics to the poles to feed on the huge amount of summer krill. If the krill peak occurs earlier in the season, the whales must adapt by arriving earlier, or be left hungry.

Krill predators. a. crabeater seal (Lobodon carcinophaga), b. Adelie penguins (Pygoscelis adeliae), c. Antarctic fur seal (Arctocephalus gazella), d. humpback whale (Megaptera novaeangliae).
Photo credits (in order a-d): Kevin Neff, Australian Antarctic Division; Mark Hindell, Institute for Marine and Antarctic Studies; Colin Lee Hong, Australian Antarctic Division; Anthony Hull, Australian Antarctic Division.

Looking ahead

Changes to krill growth habitat may damage more than the ocean food web. Demand for krill oil in health supplements and aquaculture feed is on the rise, and krill are the target of the Southern Ocean’s largest fishery. Anticipating changes in krill availability is crucial to informing the fishery’s sustainable management.

Many environmental drivers interact to create good krill habitat. More research is required, including better models, and an improved understanding of what drives krill to reproduce and survive.

But by examining changes in phytoplankton, we’ve taken significant strides towards predicting climate change impacts on krill and the wider Antarctic marine ecosystem.




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The Conversation


Devi Veytia, PhD student , University of Tasmania and Stuart Corney, Senior lecturer, University of Tasmania

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

Seafloor currents sweep microplastics into deep-sea hotspots of ocean life



A rockfish hides in a red tree coral in the deep sea.
Geofflos

Ian Kane, University of Manchester and Michael Clare, National Oceanography Centre

What if the “great ocean garbage patches” were just the tip of the iceberg? While more than ten million tonnes of plastic waste enters the sea each year, we actually see just 1% of it – the portion that floats on the ocean surface. What happens to the missing 99% has been unclear for a while.

Plastic debris is gradually broken down into smaller and smaller fragments in the ocean, until it forms particles smaller than 5mm, known as microplastics. Our new research shows that powerful currents sweep these microplastics along the seafloor into large “drifts”, which concentrate them in astounding quantities. We found up to 1.9 million pieces of microplastic in a 5cm-thick layer covering just one square metre – the highest levels of microplastics yet recorded on the ocean floor.

While microplastics have been found on the seafloor worldwide, scientists weren’t sure how they got there and how they spread. We thought that microplastics would separate out according to how big or dense they were, in a similar manner to natural sediment. But plastics are different – some float, but more than half of them sink.




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Plastics which once floated can sink as they become coated in algae, or if bound up with other sticky minerals and organic matter. Recent research has shown that rivers transport microplastics to the ocean too, and laboratory experiments revealed that giant underwater avalanches of sediment can transport these tiny particles along deep-sea canyons to greater depths.

We’ve now discovered how a global network of deep-sea currents transports microplastics, creating plastic hotspots within vast sediment drifts. By catching a ride on these currents, microplastics may be accumulating where deep-sea life is abundant.

Once plastic debris has broken down and sinks to the ocean floor, currents sweep the particles into vast drifts.
Ian Kane, Author provided

From bedroom floors to the seafloor

We surveyed an area of the Mediterranean off the western coast of Italy, known as the Tyrrhenian Sea, and studied the bottom currents that flow near the seafloor. These currents are driven by differences in water salinity and temperature as part of a system of ocean circulation that spans the globe. Seafloor drifts of sediment can be many kilometres across and hundreds of metres high, forming where these currents lose their strength.

We analysed sediment samples from the seafloor taken at depths of several hundred metres. To avoid disturbing the surface layer of sediment, we used samples taken with box-cores, which are like big cookie cutters. In the laboratory, we separated microplastics from the sediment and counted them under microscopes, analysing them using infra-red spectroscopy to find out what kinds of plastic polymer types were there.

A microplastic fibre seen under a microscope.
Ian Kane, Author provided

Most microplastics found on the seafloor are fibres from clothes and textiles. These are particularly insidious, as they can be eaten and absorbed by organisms. Although microplastics on their own are often non-toxic, studies show the build-up of toxins on their surfaces can harm organisms if ingested.

These deep ocean currents also carry oxygenated water and nutrients, meaning that the seafloor hotspots where microplastics accumulate may also be home to important ecosystems such as deep-sea coral reefs that have evolved to depend on these flows, but are now receiving huge quantities of microplastics instead.

What was once a hidden problem has now been uncovered – natural currents and the flow of plastic waste into the ocean are turning parts of the seafloor into repositories for microplastics. The cheap plastic goods we take for granted eventually end up somewhere. The clothes that may only last weeks in your wardrobe linger for decades to centuries on the seafloor, potentially harming the unique and poorly understood creatures that live there.The Conversation

Ian Kane, Reader in Geology, University of Manchester and Michael Clare, Principal Researcher in Marine Geoscience, National Oceanography Centre

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

5 big environment stories you probably missed while you’ve been watching coronavirus



Shutterstock

Rod Lamberts, Australian National University and Will J Grant, Australian National University

Good news: COVID-19 is not the only thing going on right now!

Bad news: while we’ve all been deep in the corona-hole, the climate crisis has been ticking along in the background, and there are many things you may have missed.

Fair enough – it’s what people do. When we are faced with immediate, unambiguous threats, we all focus on what’s confronting us right now. The loss of winter snow in five or ten years looks trivial against images of hospitals pushed to breaking point now.




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As humans, we also tend to prefer smaller, short-term rewards over larger long-term ones. It’s why some people would risk illness and possible prosecution (or worse, public shaming) to go to the beach with their friends even weeks after social distancing messages have become ubiquitous.

But while we might need to ignore climate change right now if only to save our sanity, it certainly hasn’t been ignoring us.

So here’s what you may have missed while coronavirus dominates the news cycle.

Heatwave in Antarctica

Antarctica is experiencing alarmingly balmy weather.
Shutterstock

On February 6 this year, the northernmost part of Antarctica set a new maximum temperature record of 18.4℃. That’s a pleasant temperature for an early autumn day in Canberra, but a record for Antarctica, beating the old record by nearly 1℃.

That’s alarming, but not as alarming as the 20.75℃ reported just three days later to the east of the Antarctic Peninsula at Marambio station on Seymour Island.




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Bleaching the reef

The Intergovernmental Panel on Climate Change has warned a global average temperature rise of 1.5℃ could wipe out 90% of the world’s coral.

As the world looks less likely to keep temperature rises to 1.5℃, in 2019 the five-year outlook for Australia’s Great Barrier Reef was downgraded from “poor” to “very poor”. The downgrading came in the wake of two mass bleaching events, one in 2016 and another in 2017, damaging two-thirds of the reef.

And now, in 2020, it has just experienced its third in five years.

Of course, extreme Antarctic temperatures and reef bleaching are the products of human-induced climate change writ large.

But in the short time since the COVID-19 crisis began, several examples of environmental vandalism have been deliberately and specifically set in motion as well.




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Coal mining under a Sydney water reservoir

The Berejiklian government in New South Wales has just approved the extension of coal mining by Peabody Energy – a significant funder of climate change denial – under one of Greater Sydney’s reservoirs. This is the first time such an approval has been granted in two decades.

While environmental groups have pointed to significant local environmental impacts – arguing mining like this can cause subsidence in the reservoir up to 25 years after the mining is finished – the mine also means more fossil carbon will be spewed into our atmosphere.

Peabody Energy argues this coal will be used in steel-making rather than energy production. But it’s still more coal that should be left in the ground. And despite what many argue, you don’t need to use coal to make steel.




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Victoria green-lights onshore gas exploration

In Victoria, the Andrews government has announced it will introduce new laws into Parliament for what it calls the “orderly restart” of onshore gas exploration. In this legislation, conventional gas exploration will be permitted, but an existing temporary ban on fracking and coal seam gas drilling will be made permanent.

The announcement followed a three-year investigation led by Victoria’s lead scientist, Amanda Caples. It found gas reserves in Victoria “could be extracted without harming the environment”.

Sure, you could probably do that (though the word “could” is working pretty hard there, what with local environmental impacts and the problem of fugitive emissions). But extraction is only a fraction of the problem of natural gas. It’s the subsequent burning that matters.




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Trump rolls back environmental rules

Meanwhile, in the United States, the Trump administration is taking the axe to some key pieces of environmental legislation.

One is an Obama-era car pollution standard, which required an average 5% reduction in greenhouse emissions annually from cars and light truck fleets. Instead, the Trump administration’s “Safer Affordable Fuel Efficient Vehicles” requires just 1.5%.

The health impact of this will be stark. According to the Environmental Defense Fund, the shift will mean 18,500 premature deaths, 250,000 more asthma attacks, 350,000 more other respiratory problems, and US$190 billion in additional health costs between now and 2050.

And then there are the climate costs: if manufacturers followed the Trump administration’s new looser guidelines it would add 1.5 billion tonnes of carbon dioxide to the atmosphere, the equivalent of 17 additional coal-fired power plants.




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And so…

The challenges COVID-19 presents right now are huge. But they will pass.

The challenges of climate change are not being met with anything like COVID-19 intensity. For now, that makes perfect sense. COVID-19 is unambiguously today. Against this imperative, climate change is still tomorrow.

But like hangovers after a large celebration, tomorrows come sooner than we expect, and they never forgive us for yesterday’s behaviour.The Conversation

Rod Lamberts, Deputy Director, Australian National Centre for Public Awareness of Science, Australian National University and Will J Grant, Senior Lecturer, Australian National Centre for the Public Awareness of Science, Australian National University

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

We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy



Author supplied

Terry Hughes, James Cook University and Morgan Pratchett, James Cook University

The Australian summer just gone will be remembered as the moment when human-caused climate change struck hard. First came drought, then deadly bushfires, and now a bout of coral bleaching on the Great Barrier Reef – the third in just five years. Tragically, the 2020 bleaching is severe and the most widespread we have ever recorded.

Coral bleaching at regional scales is caused by spikes in sea temperatures during unusually hot summers. The first recorded mass bleaching event along Great Barrier Reef occurred in 1998, then the hottest year on record.




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Since then we’ve seen four more mass bleaching events – and more temperature records broken – in 2002, 2016, 2017, and again in 2020.

This year, February had the highest monthly sea surface temperatures ever recorded on the Great Barrier Reef since the Bureau of Meteorology’s records began in 1900.

Not a pretty picture

We surveyed 1,036 reefs from the air during the last two weeks in March, to measure the extent and severity of coral bleaching throughout the Great Barrier Reef region. Two observers, from the ARC Centre of Excellence for Coral Reef Studies and the Great Barrier Reef Marine Park Authority, scored each reef visually, repeating the same procedures developed during early bleaching events.

The accuracy of the aerial scores is verified by underwater surveys on reefs that are lightly and heavily bleached. While underwater, we also measure how bleaching changes between shallow and deeper reefs.




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Of the reefs we surveyed from the air, 39.8% had little or no bleaching (the green reefs in the map). However, 25.1% of reefs were severely affected (red reefs) – that is, on each reef more than 60% of corals were bleached. A further 35% had more modest levels of bleaching.

Bleaching isn’t necessarily fatal for coral, and it affects some species more than others. A pale or lightly bleached coral typically regains its colour within a few weeks or months and survives.

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

But when bleaching is severe, many corals die. In 2016, half of the shallow water corals died on the northern region of the Great Barrier Reef between March and November. Later this year, we’ll go underwater to assess the losses of corals during this most recent event.

Compared to the four previous bleaching events, there are fewer unbleached or lightly bleached reefs in 2020 than in 1998, 2002 and 2017, but more than in 2016. Similarly, the proportion of severely bleached reefs in 2020 is exceeded only by 2016. By both of these metrics, 2020 is the second-worst mass bleaching event of the five experienced by the Great Barrier Reef since 1998.

The unbleached and lightly bleached (green) reefs in 2020 are predominantly offshore, mostly close to the edge of the continental shelf in the northern and southern Great Barrier Reef. However, offshore reefs in the central region were severely bleached again. Coastal reefs are also badly bleached at almost all locations, stretching from the Torres Strait in the north to the southern boundary of the Great Barrier Reef Marine Park.



CC BY-ND

For the first time, severe bleaching has struck all three regions of the Great Barrier Reef – the northern, central and now large parts of the southern sectors. The north was the worst affected region in 2016, followed by the centre in 2017.

In 2020, the cumulative footprint of bleaching has expanded further, to include the south. The distinctive footprint of each bleaching event closely matches the location of hotter and cooler conditions in different years.

Poor prognosis

Of the five mass bleaching events we’ve seen so far, only 1998 and 2016 occurred during an El Niño – a weather pattern that spurs warmer air temperatures in Australia.

But as summers grow hotter under climate change, we no longer need an El Niño to trigger mass bleaching at the scale of the Great Barrier Reef. We’ve already seen the first example of back-to-back bleaching, in the consecutive summers of 2016 and 2017. The gap between recurrent bleaching events is shrinking, hindering a full recovery.

For the first time, severe bleaching has struck all three regions of the Great Barrier Reef.
ARC Centre of Excellence for Coral Reef Studies

After five bleaching events, the number of reefs that have escaped severe bleaching continues to dwindle. Those reefs are located offshore, in the far north and in remote parts of the south.

The Great Barrier Reef will continue to lose corals from heat stress, until global emissions of greenhouse gasses are reduced to net zero, and sea temperatures stabilise. Without urgent action to achieve this outcome, it’s clear our coral reefs will not survive business-as-usual emissions.




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The Conversation


Terry Hughes, Distinguished Professor, James Cook University and Morgan Pratchett, Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University

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

I studied what happens to reef fish after coral bleaching. What I saw still makes me nauseous



Victor Huertas, Author provided

Jodie L. Rummer, James Cook University

The Great Barrier Reef is suffering its third mass bleaching event in five years. It follows the record-breaking mass bleaching event in 2016 that killed a third of Great Barrier Reef corals, immediately followed by another in 2017.

While we don’t know if fish populations declined from the 2016 bleaching disaster, one 2018 study did show the types of fish species on some coral reefs changed. Our study dug deeper into fish DNA.

I was part of an international team of scientists that, for the first time, tracked wild populations of five species of coral reef fish before, during, and after the 2016 marine heatwave.

From a scientific perspective, the results are fascinating and world-first.

Marine heatwaves are now becoming more frequent and more severe with climate change. Corals are bleaching, as pictured here.
Jodie Rummer, Author provided

We used gene expression as a tool to survey how well fish can handle hotter waters. Gene expression is the process where a gene is read by cell machinery and creates a product such as a protein, resulting in a physical trait.

We know many tropical coral reef fish are already living at temperatures close to their upper limits. Our findings can help predict which of these species will be most at risk from repeated heatwaves.




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But from a personal perspective, I still feel nauseous thinking about what the reef looked like during this project. I’ll probably feel this way for a long time.

Rewind to November 2015

We were prepared. Back then we didn’t know the reef was about to bleach and lead to widespread ecological devastation. But we did anticipate that 2016 would be an El Niño year. This is a natural climate cycle that would mean warm summer waters in early 2016 would stick around longer than usual.

But we can’t blame El Niño – the ocean has already warmed by 1°C above pre-industrial levels from continued greenhouse gas emissions. What’s more, marine heatwaves are becoming more frequent and severe with climate change.

Given this foresight, we took some quick liver biopsies from several coral reef fish species at our field site in December 2015, just in case.

Coral bleaching at Magnetic Island, March 2020.
Victor Huertas, Author provided

A couple months later, we were literally in hot water

In February 2016, my colleague and I were based on Lizard Island in the northern part of the Great Barrier Reef working on another project.

The low tides had shifted to the afternoon hours. We were collecting fish in the shallow lagoon off the research station, and our dive computers read that the water temperature was 33°C.




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We looked at each other. These are the temperatures we use to simulate climate change in our laboratory studies for the year 2050 or 2100, but they’re happening now.

Over the following week, we watched corals turn fluorescent and then bone-white.

The water was murky with slime from the corals’ immune responses and because they were slowly exuding their symbiotic zooxanthellae – the algae that provides corals with food and the vibrant colours we know and love when we think about a coral reef. The reef was literally dying before our eyes.

A third of the corals on the Great Barrier Reef perished after the 2016 heatwave.
Jodie Rummer, Author provided

Traits for dealing with heatwaves

We sampled fish during four time periods around this devastating event: before, at the start, during, and after.

Some genes are always “switched on”, regardless of environmental conditions. Other genes switch on or off as needed, depending on the environment.

If we found these fish couldn’t regulate their gene expression in response to temperature stress, then the functions – such as metabolism, respiration, and immune function – also cannot change as needed. Over time, this could compromise survival.




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The plasticity (a bit like flexibility) of these functions, or phenotypes, is what buffers an organism from environmental change. And right now, this may be the only hope for maintaining the health of coral reef ecosystems in the face of repeated heatwave events.

So, what were the fish doing?

We looked at expression patterns of thousands of genes. We found the same genes responded differently between species. In other words, some fish struggled more than others to cope with marine heatwaves.

Ostorhinchus doederleini, a species of cardinalfish, is bad at coping with marine heatwaves.
Göran Nilsson, Author provided

The species that coped the least was a nocturnal cardinalfish species (Cheilodipterus quinquelineatus). We found it had the lowest number of differentially expressed genes (genes that can switch on or off to handle different stressors), even when facing the substantial change in conditions from the hottest to the coolest months.

In contrast, the spiny damselfish (Acanthochromis polyacanthus) responded to the warmer conditions with changes in the expression of thousands of genes, suggesting it was making the most changes to cope with the heatwave conditions.

What can these data tell us?

Our findings not only have implications for specific fish species, but for the whole ecosystem. So policymakers and the fishing industry should screen more species to predict which will be sensitive and which will tolerate warming waters and heatwaves. This is not a “one size fits all” situation.

One of the species that showed the least amount of change under warming was Cheilodipterus quinquelineatus.
Moises Antonio Bernal de Leon, Author provided

Fish have been on the planet for more than 400 million years. Over time , they may adapt to rising temperatures or migrate to cooler waters.

But, the three recent mass bleaching events is unprecedented in human history, and fish won’t have time to adapt.




Read more:
Attention United Nations: don’t be fooled by Australia’s latest report on the Great Barrier Reef


My drive to protect the oceans began when I was a child. Now it’s my career. Despite the progress my colleagues and I have made, my nauseous feelings remain, knowing our science alone may not be enough to save the reef.

The future of the planet, the oceans, and the Great Barrier Reef lies in our collective actions to reduce global warming. What we do today will determine what the Great Barrier Reef looks like tomorrow.The Conversation

Jodie L. Rummer, Associate Professor & Principal Research Fellow, James Cook University

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

For decades, scientists puzzled over the plastic ‘missing’ from our oceans – but now it’s been found


Britta Denise Hardesty, CSIRO and Chris Wilcox, CSIRO

You’ve probably heard that our oceans have become a plastic soup. But in fact, of all the plastic that enters Earth’s oceans each year, just 1% has been observed floating on the surface. So where is the rest of it?

This “missing” plastic has been a longstanding scientific question. To date, the search has focused on oceanic gyres such as the Great Pacific Garbage Patch, the water column (the part of the ocean between the surface and the sea bed), the bottom of the ocean, and the stomachs of marine wildlife.

But our new research suggests ocean plastic is being transported back onshore and pushed permanently onto land away from the water’s edge, where it often becomes trapped in vegetation.

Of course, plastic has been reported on beaches around the world for decades. But there has been little focus on why and how coastal environments are a sink for marine debris. Our findings have big implications for how we tackle ocean plastic.

New research shows a significant amount of plastic pollution from our oceans ends up back on land, where it gets trapped.

The hunt for marine pollution

Our separate, yet-to-be-published research has found around 90% of marine debris that enters the ocean remains in the “littoral zone” (the area of ocean within 8km of the coast). This new study set out to discover what happens to it.

We collected data on the amount and location of plastic pollution every 100 kilometres around the entire coast of Australia between 2011 and 2016. Debris was recorded at 188 locations along the Australian coastline. Of this, 56% was plastic, followed by glass (17%) and foam (10%).

Data was recorded approximately every 100 kilometres along the coast of Australia. Of the marine debris recorded, more than half was plastic.

The debris was a mix of litter from people and deposition from the ocean. The highest concentrations of plastic pollution were found along coastal backshores – areas towards the inland edge of the beach, where the vegetation begins. The further back from the water’s edge we went, the more debris we found.

The amount of marine debris, and where it ends up, is influenced by onshore wave activity and, to a lesser extent, wind activity. Densely populated areas and those where the coast was easily accessible were hotspots for trapped plastics.




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Think about what you see on your beach. Smaller debris is often found near the water’s edge, while larger items such as drink bottles, plastic bags and crisp packets are often found further back from the water, often trapped in vegetation.

We also found more debris near urban areas where rivers and creeks enter the ocean. It could be that our trash is being trapped by waterways before it gets to the sea. We’re finding similar patterns in other countries we’re surveying around the Asia Pacific and beyond.

This pollution kills and maims wildlife when they mistake it for food or get tangled in it. It can damage fragile marine ecosystems by smothering sensitive reefs and transporting invasive species and is potentially a threat to human health if toxins in plastics make their way through the food chain to humans.

It can also become an eyesore, damaging the economy of an area through reduced tourism revenue.

Onshore waves, wind and areas with denser human populations influences where and how much marine debris there is along our coastlines.
CSIRO

Talking rubbish

Our findings highlight the importance of studying the entire width of coastal areas to better understand how much, and where, debris gets trapped, to inform targeted approaches to managing all this waste.

Plastic pollution can be reduced through local changes such as water refill stations, rubbish bins, incentives and awareness campaigns. It can also be reduced through targeted waste management policies to reduce, reuse and recycle plastics. We found container deposit schemes to be a particularly effective incentive in reducing marine pollution.




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This discussion is particularly timely. The National Plastics Summit in Canberra last week brought together governments, industry and non-government organisations to identify new solutions to the plastic waste challenge, and discuss how to meet targets under the National Waste Policy Action Plan. Understanding that so much of our debris remains local, and trapped on land, provides real opportunities for successful management of our waste close to the source. This is particularly critical given the waste export ban starting July 1 at the latest.

Plastic in our oceans is increasing. It’s clear from our research that waste management strategies on land must accommodate much larger volumes of pollution than previously estimated. But the best way to keep plastic from our ocean and land is to stop putting it in.

Arianna Olivelli contributed to this article, and the research upon which it was based.




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The Conversation


Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO and Chris Wilcox, Senior Research Scientist, CSIRO

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

The story of a wave: from wind-blown ripples to breaking on the beach



By the time a wave reaches shore, it may have travelled tens of thousands of kilometres.
Ian Mitchinson / Shutterstock

Shane Keating, UNSW

It’s a cliché, but Aussies love the beach. And little wonder: with 36,000 kilometres of coastline, Australia is blessed with some of the best beaches in the world.

Around 20 million Australians live within 50 kilometres of the coast. As summer temperatures soar, we flock to the ocean to splash, swim, surf, paddle, and plunge in the waves.

But where do those waves come from? How do they form, and why do they break? As it turns out, what we see at the shore is just the last few moments of an epic journey.




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Great waves from tiny ripples grow

The waves we see crashing on the beach can begin their lives tens of thousands of kilometres away. Surface waves, as they are known, are born when the wind blows over the ocean, amplifying small ripples and transferring momentum from the atmosphere to the water.

The height of the wave depends on how long the wind is blowing and the distance – or fetch – over which it blows. The largest waves are created by distant storms, which churn up the surface of the ocean and radiate waves outwards like ripples in a pond.

Surface waves don’t move the water itself very far – each water molecule travels forward and back in a circle a few meters across and ends up back at its starting point.

As the wave crest rises, water molecules gather gravitational potential energy that is released as kinetic energy when the water descends into the trough of the wave. This energy is then passed onto the next crest in a see-saw of kinetic and potential energy that can propagate across an entire ocean basin.

The mounting wave

Once a wave leaves the open ocean and approaches land, the sea floor begins to exert its influence. Surface waves transmit their energy more slowly in shallow water than in deep water. This causes energy to pile up near the shore. Waves start to shoal, becoming taller, steeper, and more closely spaced.

Once a wave grows too steep to hold together, it breaks. Breaking waves come in different varieties.

Spilling breakers, which crumble gently into white water, occur when the sea floor rises relatively slowly.

By contrast, plunging breakers – the classic rolling waves favoured by surfers – form when the sea floor rises sharply, particularly near reefs and rocky headlands.

Finally, surging waves occur when the shore is almost vertical. These waves don’t produce breakers but rather a rhythmic rise and fall of the sea surface.

Bend it like bathymetry

The shape or topography of the sea floor – called bathymetry – can have remarkable effects on breaking waves. If the depth of the sea floor changes parallel to the coast, incoming waves will refract or bend so their crests line up with the shoreline.

The effect can be clearly seen near headlands: waves close to the headland move slowly because the water is shallow, while waves further out move more quickly. This causes waves to curl around the headland like a marching band rounding a corner.

Bathymetry is also responsible for some of the biggest waves on Earth. Famous big wave surf spots like Mavericks in Northern California and Nazaré in Portugal benefit from undersea canyons that refract incoming waves and focus them into monsters. The Nazaré wave originates from an undersea canyon almost 5 kilometres deep to produce waves as tall as an eight-storey building.




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Don’t risk the rip

The story of a wave doesn’t end when it breaks, however. Breaking waves push water towards the shore, raising the water level. This water will try to flow back offshore via the lowest point along the beach. The result is a rip current: a swift, narrow current that flows out to sea.

Rip currents are Australia’s number one coastal hazard, responsible for more fatalities per year than shark attacks, bush fires, floods, and cyclones combined. Inexperienced swimmers caught in a rip can panic and try to swim against the current, which is a dangerous recipe for exhaustion. Yet most Australians are unable to identify a rip current, and two-thirds of those who think they can get it wrong.

Purple dye traces the path of a rip current.
Rob Brander

To spot a rip, look for a gap in the waves, a dark channel, or ripples surrounded by smoother water. The safest thing to do is to stick to patrolled beaches and swim between the flags. If you do find yourself caught in a rip, Surf Lifesaving Australia advises you to stay calm and conserve your energy.

Rip currents are usually quite narrow, so swim at right angles to the current until you are outside the rip. If you are too tired to swim, tread water and let yourself go with the flow until the rip weakens and you can signal for help.

Above all, if you are unsure, don’t risk the rip. Sit back and enjoy the waves from a safe distance instead.The Conversation

Shane Keating, Senior Lecturer in Mathematics and Oceanography, UNSW

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

Acidic oceans are corroding the tooth-like scales of shark skin



CT scan of a catshark hatchling head. Note the ridged scales.
Rory Cooper, Kyle Martin & Amin Garbout/Natural History Museum London, Author provided

Rory Cooper, University of Sheffield

Shark skin might look perfectly smooth, but inspect it under a microscope and you’ll notice something strange. The entire outer surface of a shark’s body is actually covered in sharp, little scales known as denticles. More remarkable still, these denticles are incredibly similar to human teeth, as they’re also comprised of dentine and enamel-like materials.

Your dentist will no doubt have warned you that acidic drinks like fizzy cola damage your teeth. This is because acid can dissolve the calcium and phosphate in the enamel tooth covering. For the first time, scientists have discovered a similar process acting on the tooth-like scales of sharks in the ocean.




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The carbon dioxide (CO₂) that humans release into the atmosphere doesn’t just heat the planet. As more of it dissolves in the ocean, it’s gradually increasing the acidity of seawater. In the past 200 years, the ocean has absorbed 525 billion tonnes of CO₂ and become 30% more acidic as a result. Now scientists worry that the lower pH is affecting one of the ocean’s top predators.

Denticles have sharp ridges and are arranged in an overlapping pattern, similar to chainmail.
Rory Cooper, Author provided

An unwelcome sea change

Over hundreds of millions of years, the denticles that make up shark skin have evolved to allow sharks to thrive in different environments. Different species have distinct denticle shapes and patterns that enable a range of remarkable functions. I’ve spent the last four years attempting to understand how the development of these scales is genetically controlled in shark embryos, and how their intricate details give each species an edge.

Denticles have highly specialised ridges which help reduce drag by up to 10%, allowing sharks to swim further and faster while using less energy. This works in a similar fashion to the ridges in the hulls of speed boats, which help the vessel move more efficiently through the water. In fact, these scales are so effective at reducing drag that scientists and engineers have long tried to create shark skin-inspired materials for boats and aircraft that can help them travel further on less fuel.

A catshark embryo about 80 days after fertilisation.
Rory Cooper, Kyle Martin & Amin Garbout/Natural History Museum London, Author provided

The patterning of denticles also works as a defensive armour, which protects sharks from their environment and from other predators. Some female sharks – such as the small-spotted catshark – have even developed a region of enlarged denticles which provide protection from a male shark’s bites during mating.

The changing chemistry of the ocean has been linked to coral bleaching, but its effect on other marine animals is less clear. To address this, researchers exposed puffadder shysharks – a species found off the coast of South Africa – to different levels of acidity in aquariums, and used a high-resolution imaging technique to examine the effect of acid exposure on their skin. After just nine weeks, they found that increased water acidity had weakened the surfaces of their denticles.

The puffadder shyshark (Haploblepharus edwardsii) is a slow moving species that lives on the sea floor.
Derekkeats/Wikipedia, CC BY-SA

Corrosion and weakening of the denticle surface could degrade the highly specialised drag-reducing ridges, affecting the ability of these sharks to swim and hunt. Many shark species are top-level predators, so if they’re not able to hunt as effectively, this might have an unpredictable impact on the population size of their prey and other animals in the complex marine environment. Some species of shark need to swim constantly to keep oxygen-rich water flowing over their gills and to expel CO₂ – another process which might be hindered by increased drag.




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Sharks belong to an ancient group of vertebrates known as the cartilaginous fishes, which split from the bony fishes – a lineage that later gave rise to humans – roughly 450 million years ago. Sharks, and other cartilaginous fish like rays, arose long before the dinosaurs, and have outlived multiple mass extinction events. But the rate of change in the marine environment over the last few centuries is an unprecedented challenge. These ancient predators may struggle to adapt to the fastest known change in ocean chemistry in the last 50 million years.The Conversation

Rory Cooper, PhD Researcher in Evolutionary Developmental Biology, University of Sheffield

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