On ocean acidification

Eight-Year Study Confirms "All Sea Life" Will Be Affected by Acidic Oceans

Dahr Jamail

Sardines congregate at Espiritu Santo, Mexico, on June 13, 2015. (Photo: Alejandro Prieto / Barcroft Imag / Barcroft Media via Getty Images)

The recently published Biological Impacts of Ocean Acidification report is an eight-year-long study by more than 250 scientists investigating the impact of increasingly acidic oceans on sea life.

The chemistry of oceans has been changed by anthropogenic climate disruption (ACD), as the oceans absorb carbon dioxide humans are emitting into the atmosphere. Carbon dioxide produces carbonic acid, which lowers the pH of seawater.

The study is a product of the BIOACID project, which is based in Germany.

The research shows that all sea life will be affected by the increasing acidification. Just one example: The numbers of baby cod that grow into full adulthood could fall anywhere from one-quarter to just one-twelfth of today's numbers.

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Ocean acidification

Damage wrought by acidic oceans hurts more than marine life, lasts longer than you think

Phys.org,

11 July, 2016

A milky white cloud blooms in the Barents Sea, so vast it can be seen from space.

It's not the result of some toxic chemical spill or the sinking of a dairy-filled tanker - it's the handiwork of millions of microscopic algae, doing what their kind have done for millions of years.

The algae, Emiliania huxleyi, somewhat mysteriously produce ultra-thin scales made of chalk that surround their single-celled bodies.

While it's not exactly clear how the scales benefit the algae, scientists say they provide an important benefit to the rest of the world

.

To build up their chalky armor, E. huxleyi eat up the dissolved carbon in the water around them. When the phytoplankton grow new shells, they shed the old ones, which sink to the bottom of the ocean.

As more carbon dioxide builds up in the atmosphere and gets absorbed into the ocean, E. huxleyi and similar types of these calcifying phytoplankton are there to capture and store it away - just as trees "inhale" carbon dioxide.

The operation is so massive and industrious that an ancient species of phytoplankton, through a similar process of scale-building and shedding, gave the famous White Cliffs of Dover in southeastern England their distinctive color as their shells piled up over tens of millions of years.

Though carbon dioxide fuels this undersea industry, it also threatens to destroy it, according to a study published Friday in Science Advances.

For calcifying phytoplankton, of which E. huxleyi is the most abundant species, some extra carbon in the environment means more fuel for scale-making. But that's only beneficial to a certain point.

As humans fill the air with the carbon dioxide and greenhouse gases that cause global warming, much of that carbon gets dissolved in the ocean, causing the water to acidify.

Sometimes called the twin of global warming, ocean acidification causes corals and shellfish, whose shells are made of the same stuff as E. huxleyi's scales, to disintegrate.

A more acidic ocean eventually will cause phytoplankton like E. huxleyi to abandon their calcifying process. As the phytoplankton lose their appetite for carbon, they leave more of it in the environment. This, in turn, could worsen the effects of climate change, said Thorsten Reusch, a marine ecologist at the GEOMAR Helmholtz Centre for Ocean Research Kiel and senior author of the study.

To find out how phytoplankton will adapt to future sea changes, Reusch and Lothar Schlueter, then a doctoral student, needed to simulate the ocean conditions of the future.

In the lab, the scientists placed identical clones of E. huxleyi in varying levels of "acidified" oceans, including one that replicated conditions found today.

In the lab, E. huxleyi grow extremely fast, producing a new generation about once a day. Over four years, the algae copied themselves 2,100 times, essentially allowing the scientists to watch how the species will evolve under future ocean conditions.

"We can have the organisms of tomorrow in the lab of today," Reusch said. "It's like 'Jurassic Park' in reverse."

In the first year of the experiment, acidified E. huxleyi reacted by initially reducing their scale productivity. However, the algae eventually adapted to the new conditions and took up calcification again.

But in highly acidified oceans, phytoplankton can't produce scales and maintain their proper body chemistry. Instead of forming scales, they switch to survival mode. After four years of simulated ocean acidification, the phytoplankton shut off their scale production.

"They don't like a more acidic ocean," Reusch said.

When the researchers returned the algae to "normal" conditions, they went right back to work making their sales.

"They know when to reduce calcification," Reusch said. "They just switch it off when it's costly, but they switch it back on when the conditions are normal."

Phytoplankton are vitally important to the way oceans - and the world - work.

The microscopic algae form the base of the marine food web and are responsible for producing much of the world's oxygen.

"Every second breath you take comes from their photosynthesis," Reusch said.

Even though the study found it's possible to restore phytoplankton's carbon-cycling ability by returning them to an un-acidified ocean, such a scenario is "not foreseeable," Reusch said. Even if we reduce atmospheric carbon dioxide now, he said, ocean acidification is likely to continue.

"We have to live with ocean acidification for hundreds of years," he said.

 Explore further: Researchers explore plankton's shifting role in deep sea carbon storage

More information: Long-term dynamics of adaptive evolution in a globally important phytoplankton species to ocean acidification, Science Advances  08 Jul 2016: Vol. 2, no. 7, e1501660, DOI: 10.1126/sciadv.1501660 , http://advances.sciencemag.org/content/2/7/e1501660 

The sixth extinction

Tuna and mackerel populations suffer catastrophic 74% decline, research shows

WWF says we risk losing species critical to human food security unless action is taken to halt overfishing and other threats to marine life

the Guardian,

16 September, 2015

Tuna and mackerel populations have suffered a “catastrophic” decline of nearly three quarters in the last 40 years, according to new research.

WWF and the Zoological Society of London found that numbers of the scombridae family of fish, which also includes bonito, fell by 74% between 1970 and 2012, outstripping a decline of 49% for 1,234 ocean species over the same period.

The conservation charity warned that we face losing species critical to human food security, unless drastic action is taken to halt overfishing and other threats to marine life.

Louise Heaps, chief advisor on marine policy at WWF UK, said: “This is catastrophic. We are destroying vital food sources, and the ecology of our oceans.”

Attention in recent years has focused on species such as bluefin tuna, now on the verge of extinction in the Pacific, but other close relatives commonly found on restaurant menus or in tins, such as yellowtail tuna and albacore, are now also becoming increasingly scarce. Only skipjack, also often tinned, is showing “a surprising degree of resilience”, according to Heaps, one of the authors of the Living Blue Planet report, published on Wednesday.

Other species suffering major declines include sea cucumbers, a luxury food in Asia, which have fallen 98% in number in the Galapagos and 94% in in the Egyptian Red Sea. Populations of endangered leatherback turtles, which can be seen in UK waters, have plummeted.

Overfishing is not the only culprit behind a halving of marine species since 1970. Pollution, including plastic detritus which can build up in the digestive systems of fish; the loss of key habitats such as coastal mangrove swamps; and climate change are also taking a heavy toll, with the oceans becoming more acidic as a result of the carbon dioxide we are pouring into the atmosphere.

“I am terrified about acidification,” Heaps told the Guardian. “That situation is looking very bleak. We were taught in the 1980s that the solution to pollution is dilution, but that suggests the oceans have an infinite capacity to absorb our pollution. That is not true, and we have reached the capacity now.”

She predicts that all of the world’s coral reefs could be effectively lost by 2050, if current trends are allowed to continue unchecked, and said that evidence of the effects of acidification – which damages tiny marine animals that rely on calcium to make their shells and other organs - could be found from the Antarctic to the US west coast.

Although overfishing is a global problem, the Pacific is of particular concern, as the Chinese, Japanese and Korean fleets are among the world’s biggest, greater in size and fishing capacity than Europe’s

Chinese fishermen are also increasingly fishing in other waters, expanding their reach. Shark-finning, the practice of removing only the fins from sharks and throwing the bodies back, to make the Asian delicacy shark-fin soup, has taken a severe toll on stocks, with a quarter of shark species predicted to become extinct in a decade if nothing is done

However, Heaps said there were solutions. “It’s not all doom-and-gloom. There are choices we can make. But it is urgent.”

Overfishing can be managed with better governance – Heaps points to the recovery in North Sea cod stocks as an example of how management can work. She also urged governments to adopt the sustainable development goals, proposed by the United Nations and including provisions for protecting marine life, at the UN general assembly later this month.

Earth has lost half of its wildlife in the past 40 years, says WWF

Heaps urged people to eat fish certified as sustainable by the Marine Stewardship Council (MSC), which examines fisheries against a range of criteria to ensure that they are being properly managed. An increasing number of fisheries have been accredited by the MSC, and at present about half of global white fish stocks are certified, including many in the North Sea.

She called for more partnerships between private sector fishing fleets and governments, in order to conserve stocks. “We need to keep [fishermen] on board, because they must see that good governance is in their interests,” she said.