Saving Seafood

Ocean acidification causing coral ‘osteoporosis’ on iconic reefs

August 28, 2020 — In a paper published Aug. 27, 2020, in the journal Geophysical Research Letters, researchers show a significant reduction in the density of coral skeleton along much of the Great Barrier Reef — the world’s largest coral reef system — and also on two reefs in the South China Sea, which they attribute largely to the increasing acidity of the waters surrounding these reefs since 1950.

“This is the first unambiguous detection and attribution of ocean acidification’s impact on coral growth,” says lead author and WHOI scientist Weifu Guo. “Our study presents strong evidence that 20th century ocean acidification, exacerbated by reef biogeochemical processes, had measurable effects on the growth of a keystone reef-building coral species across the Great Barrier Reef and in the South China Sea. These effects will likely accelerate as ocean acidification progresses over the next several decades.”

Roughly a third of global carbon dioxide emissions are absorbed by the ocean, causing an average 0.1 unit decline in seawater pH since the pre-industrial era. This phenomenon, known as ocean acidification, has led to a 20 percent decrease in the concentration of carbonate ions in seawater. Animals that rely on calcium carbonate to create their skeletons, such as corals, are at risk as ocean pH continues to decline. Ocean acidification targets the density of the skeleton, silently whittling away at the coral’s strength, much like osteoporosis weakens bones in humans.

“The corals aren’t able to tell us what they’re feeling, but we can see it in their skeletons,” said Anne Cohen, a WHOI scientist and co-author of the study. “The problem is that corals really need the strength they get from their density, because that’s what keeps reefs from breaking apart. The compounding effects of temperature, local stressors, and now ocean acidification will be devastating for many reefs.”

Read the full story at Science Daily

Runaway warming could sink fishing and reef tourism, researchers warn

December 9, 2019 — Countries from Egypt to Mexico could lose 95% of their income from coral reef tourism, and parts of West Africa could see their ocean fisheries decline by 85% by the turn of the century if planet-warming emissions continue to rise, oceans experts warned Friday.

“Action in reducing emissions really needs to be taken, or we will be facing very important impacts” on oceans and people, said Elena Ojea, one of the authors of a new paper looking at the potential impacts of climate change on ocean economies.

The study, released at the U.N. climate negotiations in Madrid, was commissioned by the leaders of 14 countries with ocean-dependent economies, and looked at ocean fisheries and seafood cultivation industries, and coral reef tourism.

It found that reef tourism, a nearly $36-billion-a-year industry today, could see more than 90% losses globally by 2100 under a high-emissions scenario.

Countries particularly dependent on coral reef tourism – Egypt, Indonesia, Mexico, Thailand and Australia – could see income cut by 95%, the paper noted.

Ove Hoegh-Guldberg, an ocean expert at Australia’s University of Queensland and one of paper’s authors, said his country’s Great Barrier Reef tourism industry – worth billions a year a year – was already seeing losses as corals bleached and died.

Read the full story at Reuters

Climate Change Is Cooking The Oceans

August 16, 2018 — Heat waves aren’t just for land lubbers. Climate change has turned the oceans into cauldrons of scalding water, upending marine ecosystems around the world.

A new paper in Nature shows how marine heat waves have become more common and intense in recent decades, largely due to climate change. What’s worse, it shows that even if the world manages to limit warming to two degrees Celsius, the trend will continue and humans will ultimately be the main driving force for virtually every marine heat wave. If we let the world warm past that mark, the results could be catastrophic for the high seas.

The results point to the need to get marine life ready for a world of extreme heat and also take a greater focus on protecting the ocean wilderness we have left.

The role of human-caused climate change in intensifying land-based heat waves is now well-established. But less research has focused on the ocean, where extreme heat events in recent years have wiped out portions of the Great Barrier Reef, caused bull sharks to migrate further north, and left scientists scrambling to find ways to save coral. Individual events like the 2016 heat wave in the Great Barrier Reef have been tied to climate change (it made the heat wave 175 times more likely), but there hasn’t been a big picture look at the topic featuring projections into the future.

That’s what led a team of Swiss researchers used a mix of models and satellite measurements to get a handle on how marine heat waves have already changed and what the future holds for the globe. The satellite record, which runs from 1982-2016, helped ground truth the models they used to create a pre-industrial baseline—what the oceans looked like without all the extra heat trapped by greenhouse gas emissions. They then used the models to understand how climate change is affecting the extent, duration, and intensity of marine heat waves as well as project future changes.

The findings show the number of marine heat wave days doubled between 1982 and 2016, while heat waves also increased in extent and intensity. Moreover, they show that 87 percent of marine heat waves can be attributed to climate change, meaning they would not have occurred without it.

Read the full story at Gizmodo

Australia Seeks to Extend Commercial Fishing in Protected Waters

July 21, 2017 — Australia plans to allow fishing across 80 percent of its protected maritime sanctuaries, the government said on Friday in a proposal that would vastly extend commercial activity in the world’s largest marine-reserves network.

If the plan, backed by the government of Prime Minister Malcolm Turnbull, is approved by Parliament, it would be the first time a nation has scaled back its regulations in protected maritime areas. The move could potentially set a precedent for other countries, including the United States, which are considering similar reversals.

More than one-third of Australia’s waters — home to endangered species of sharks, turtles and whales — are protected by law.

Under the government’s proposal, “the boundaries of Australian Marine Parks will not change,” Josh Frydenberg, the environment minister, said in a statement. Instead, he said, the country would increase “the total area of the reserves open to fishing from 64 percent to 80 percent.”

Much of the increased fishing would take place in the Coral Sea Reserve, one of the country’s most stringently protected areas, where large-scale operations would be allowed for first time in at least five years. Most fishing is now prohibited in the park, off the continent’s northeast coast, by a so-called no-take zone.

Read the full story at the New York Times

Large Sections of Australia’s Great Reef Are Now Dead, Scientists Find

March 16, 2017 — The Great Barrier Reef in Australia has long been one of the world’s most magnificent natural wonders, so enormous it can be seen from space, so beautiful it can move visitors to tears.

But the reef, and the profusion of sea creatures living near it, are in profound trouble.

Huge sections of the Great Barrier Reef, stretching across hundreds of miles of its most pristine northern sector, were recently found to be dead, killed last year by overheated seawater. More southerly sections around the middle of the reef that barely escaped then are bleaching now, a potential precursor to another die-off that could rob some of the reef’s most visited areas of color and life.

“We didn’t expect to see this level of destruction to the Great Barrier Reef for another 30 years,” said Terry P. Hughes, director of a government-funded center for coral reef studies at James Cook University in Australia and the lead author of a paper on the reef that is being published Thursday as the cover article of the journal Nature. “In the north, I saw hundreds of reefs — literally two-thirds of the reefs were dying and are now dead.”

Read the full story at the New York Times

How a Fish That Hatches in Coral Reefs Finds Its Way Home

December 28, 2016 — The larvae of fish that live in coral reefs are tiny, and they are not very good swimmers. They are pushed by currents away from the reefs on which they were hatched for days or weeks until they learn to swim. Then, somehow, around 60 percent of them make their way back to their birthplaces, where they spend the rest of their lives.

Scientists know that they can navigate using the position of the sun by day. But they find their way at night, too, and now researchers think they know how: They are magnetic.

Researchers studied the larvae of Doederlein’s cardinalfish, Ostorhinchus doederleini, a reef fish that grows to about five inches long. They collected specimens near One Tree Island in the Great Barrier Reef, off the northeast coast of Australia.

When the larvae hatch, currents carry them north-northwest, and experiments have shown that they consistently swim south-southeast guided by the sun back to their birthplace. But to see whether magnetic forces are also at work, the researchers tested them by using a device that creates a uniform magnetic field whose direction can be manipulated.

With the larvae in a tank surrounded by the device, the scientists turned the earth’s normal magnetic north 120 degrees clockwise. The fish followed right along, swimming in the direction the researchers steered them. The study is online in Current Biology.

Read the full story at The New York Times

The Great Barrier Reef is not actually dead, but it is in serious trouble

October 17, 2016 — There is a big difference between dead and dying.

Outside Magazine published a somewhat tongue-in-cheek obituary for the Great Barrier Reef earlier this week, citing its lifespan from 25 million BC-2016. The article detailed the life of the reef, its active membership in the ecological community, its worldwide fame and the coral bleaching that has led to its deteriorating health. “The Great Barrier Reef of Australia passed away in 2016 after a long illness. It was 25 million years old,” read the article.

Immediate response on social media

The obituary was met with horror and disbelief, both by scientists and social media users alike. Russell Brainard, chief of the Coral Reef Ecosystem Program at NOAA’s Pacific Islands Fisheries Science Center, told HuffPost that he believes the article was highlighting the urgency of the situation, but that those who don’t have any context “are going to take it at face value that the Great Barrier Reef is dead.”

Many people on social media are indeed taking it at face value. Twitter users have been grieving the loss of the reef and urging followers to pay serious attention to the consequences. Many are spreading false information entirely. Rowan Jacobsen, the writer of the obituary, is a food and environmental writer, not a scientist. But the article has led some outlets to claim that scientists have declared the reef officially dead, further spreading the exaggeration.

Read the full story at WREG

Biodiversity makes reef fish more resilient in the face of climate change, research confirms

May 17, 2016 — New research confirms that biodiversity can help reef fish weather the impacts of global warming.

Reef systems with greater numbers of fish species are not just more productive but also more resilient to rising sea-surface temperatures and the temperature swings associated with climate change, according to a new study led by researchers with the Smithsonian’s Tennenbaum Marine Observatories Network.

After analyzing data from more than 4,500 fish surveys of reefs around the world to compare the effects of biodiversity and other environmental factors on global reef fish biomass, the authors of the study found that biodiversity, measured by the number of species (species diversity) and the variety of functional traits (functional diversity) within a reef system, was one of the strongest predictors of fish biomass, second only to mean sea-surface temperature.

A direct impact of the carbon emissions that continue to concentrate in Earth’s atmosphere is warmer, more acidic ocean waters, which has contributed to the bleaching of reefs around the world. Just last month, scientists announced that 99 percent of coral reefs surveyed in Australia’s Great Barrier Reef have been hit by the global bleaching event that has already taken a toll on reefs at the Pacific islands of Hawaii, Vanuatu, American Samoa, and Fiji, as well as parts of the Caribbean, the Florida Keys, and the Indian Ocean.

Read the full story at Mongabay