Ocean acidification takes a toll on California’s tide pools at nighttime

A new study, based on the most extensive set of measurements ever made in tide pools, suggests that ocean acidification will increasingly put many marine organisms at risk by exacerbating normal changes in ocean chemistry that occur overnight. Conducted along California’s rocky coastline, the study shows that the most vulnerable organisms are likely to be those with calcium carbonate shells or skeletons.

Ocean acidification is occurring as the oceans absorb increasing amounts of carbon dioxide from the atmosphere, where carbon dioxide concentrations are steadily rising due to emissions from the burning of fossil fuels. Absorption of carbon dioxide changes seawater chemistry, pushing it toward the lower, acidic end of the pH scale, although it remains slightly alkaline. A small decrease in pH affects the chemical equilibrium of ocean water, reducing the availability of carbonate ions needed by a wide range of organisms to build and maintain structures of calcium carbonate, such as the shells of mussels and oysters.

Kristy Kroeker, assistant professor of ecology and evolutionary biology at UC Santa Cruz, is a coauthor of the new study, published March 18 in Scientific Reports. “There is a lot of concern about how ocean acidification is going to affect marine species in the future, but most of our understanding comes from laboratory studies where a single organism is exposed to acidified seawater under very controlled conditions for a short period of time,” Kroeker explained. “In reality, every organism is embedded in a complex community that experiences dynamic environmental conditions that will gradually change over time.”

Calcifying organisms

In the new study, researchers closely monitored conditions in tide pools along California’s rocky coast, which are isolated from the open ocean during low tides. During the daytime, photosynthesis—the mechanism by which plants use the sun’s energy to convert carbon dioxide and water into sugar, giving off oxygen in the process—takes up carbon dioxide from the seawater and acts to reverse ocean acidification’s effects. At night, however, photosynthesis stops, while the respiration of plants and animals takes up oxygen and releases carbon dioxide. This adds carbon dioxide to the seawater and exacerbates the effects of ocean acidification, increasing the risk to calcifying organisms.

“Tide pools are home to lots of different species that regularly experience daily swings in chemistry,” Kroeker said. “Tide pools can experience particularly corrosive seawater during nighttime low tides, when all of the animals are ‘exhaling’ carbon dioxide into the water that has been cut off from the ocean.”

The research team, led by scientists at the Carnegie Institution of Science, used these natural nighttime spikes in corrosive conditions to examine how entire communities of marine species respond to natural acidification. Observing a variety of California’s natural rocky tide pools near the Bodega Marine Laboratory, they found that the rate of shell and skeletal growth was not greatly affected by seawater chemistry in the daytime. However, during low tide at night, water in the tide pools became corrosive to calcium carbonate shells and skeletons. The study found evidence that the rate at which these shells and skeletons dissolved during these nighttime periods was greatly affected by seawater chemistry.

“Unless carbon dioxide emissions are rapidly curtailed, we expect ocean acidification to continue to lower the pH of seawater,” said lead author Lester Kwiatkowski of the Carnegie Institution of Science. “This work highlights that even in today’s temperate coastal oceans, calcifying species, such as mussels and coralline algae, can dissolve during the night due to the more acidic conditions caused by community respiration.”

These results highlight the vulnerability of marine species in even the most dynamic conditions to the global process of ocean acidification, Kroeker said.

According to coauther Ken Caldeira of the Carnegie Institution, “If what we see happening along California’s coast today is indicative of what will continue in the coming decades, by the year 2050 there will likely be twice as much nighttime dissolution as there is today. Nobody really knows how our coastal ecosystems will respond to these corrosive waters, but it certainly won’t be well.”

The study was a collaborative effort by the Carnegie Institution for Science, UC Davis, and UC Santa Cruz. This work was funded by the Carnegie Institution for Science, UC Multi-campus Research Initiatives and Programs, and the National Science Foundation.

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Dual Impact of Ocean Acidification and Low-Oxygen on West Coast Foretells Future for World Oceans

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

Copyright © 2016 Seafoodnews.com

SEAFOODNEWS.COM [UW Today] By Michelle Ma – January 12, 2016

The Pacific Ocean along the West Coast serves as a model for how other areas of the ocean could respond in coming decades as the climate warms and emission of greenhouse gases like carbon dioxide increases. This region — the coastal ocean stretching from British Columbia to Mexico — provides an early warning signal of what to expect as ocean acidification continues and as low-oxygen zones expand.

Now, a panel of scientists from California, Oregon and Washington has examined the dual impacts of ocean acidification and low-oxygen conditions, or hypoxia, on the physiology of fish and invertebrates. The study, published in the January edition of the journal BioScience, takes an in-depth look at how the effects of these stressors can impact organisms such as shellfish and their larvae, as well as organisms that have received less attention so far, including commercially valuable fish and squid.

The results show that ocean acidification and hypoxia combine with other factors, such as rising ocean temperatures, to create serious challenges for marine life. These multiple-stressor effects will likely only increase as ocean conditions worldwide begin resembling those off the West Coast, which naturally expose marine life to stronger low-oxygen and acidification stressors than most other regions of the seas.

“Our research recognizes that these climate change stressors will co-occur, essentially piling on top of one another,” said co-author Terrie Klinger, professor and director of the University of Washington’s School of Marine and Environmental Affairs.

“We know that along the West Coast temperature and acidity are increasing, and at the same time, hypoxia is spreading. Many organisms will be challenged to tolerate these simultaneous stressors, even though they might be able to tolerate individual stressors when they occur on their own.”

Oceans around the world are increasing in acidity as they absorb about a quarter of the carbon dioxide released into the atmosphere each year. This changes the chemistry of the seawater and causes physiological stress to organisms, especially those with calcium carbonate shells or skeletons, such as oysters, mussels and corals.

Hypoxia, on the other hand, is a condition in which ocean waters have very low oxygen levels. At the extreme, hypoxia can result in “dead zones” where mass die-offs of fish and shellfish occur. The waters along the West Coast sometimes experience both ocean acidification and hypoxia simultaneously.

“Along this coast, we have relatively intensified conditions of ocean acidification compared with other places. And at the same time we have hypoxic events that can further stress marine organisms,” Klinger said. “Conditions observed along our coast now are forecast for the global ocean decades in the future. Along the West Coast, it’s as if the future is here now.”

Klinger is co-director of the Washington Ocean Acidification Center based at the UW and served on the West Coast Ocean Acidification and Hypoxia Science Panel, which was convened two years ago to promote coast-wide collaboration and cooperation on science and policy related to these issues.

For this paper, the authors examined dozens of scientific publications that reported physiological responses among marine animals exposed to lower oxygen levels, elevated acidity and other stressors. The studies revealed how physiological changes in marine organisms can lead to changes in animal behavior, biogeography and ecosystem structure, all of which can contribute to broader-scale effects on the marine environment.

The tri-state panel has completed this phase of its work and will wrap things up in the coming months. Among the products already published or planned are a number of scientific publications — including this synthesis piece — as well as resources for policymakers and the general public describing ocean research priorities, monitoring needs and management strategies to sustain marine ecosystems in the face of ocean acidification and hypoxia.

The group’s other papers and findings related to ocean acidification and hypoxia will soon be available on its website.

Co-authors of this paper include George Somero, Jody Beers and Steve Litvin at Stanford University’s Hopkins Marine Station; Francis Chan of Oregon State University; and Tessa Hill of the University of California, Davis.

The research was funded by the California Ocean Protection Council, the California Ocean Science Trust, the Institute for Natural Resources at Oregon State University and the National Science Foundation.

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New research maps areas most vulnerable to ocean acidification

New NOAA-led research maps the distribution of aragonite saturation state in both surface and subsurface waters of the global ocean and provides further evidence that ocean acidification is happening on a global scale. The study identifies the Arctic and Antarctic oceans, and the upwelling ocean waters off the west coasts of North America, South America and Africa as regions that are especially vulnerable to ocean acidification.

“These findings will help us better understand and develop strategies to adapt to the severity of ocean acidification in different marine ecosystems around the world,” said Richard A. Feely, a NOAA oceanographer and co-author of the study, which has been accepted for publication and can be read online in the American Geophysical Union journal Global Biogeochemical Cycles.

Ocean acidification is caused by humankind’s release of carbon dioxide emissions to the atmosphere. Excess carbon dioxide enters the ocean, reacts with water, decreases ocean pH and lowers carbonate ion concentrations, making waters more corrosive to marine species that need carbonate ions and dissolved calcium to build and maintain healthy shells and skeletons. The saturation state of seawater for a mineral such as aragonite is a measure of the potential for the mineral to form or to dissolve.

In the new study, scientists determined the saturation state of aragonite in order to map regions that are vulnerable to ocean acidification. Waters with higher aragonite saturation state tend to be better able to support shellfish, coral and other species that use this mineral to build and maintain their shells and other hard parts.

This study shows that aragonite saturation state in waters shallower than 328 feet or 100 meters depth decreased by an average of 0.4 percent per year from the decade spanning 1989-1998 to the decade spanning 1998-2010. “A decline in the saturation state of carbonate minerals, especially aragonite, is a good indicator of a rise in ocean acidification,” said Li-Qing Jiang, an oceanographer with NOAA’s Cooperative Institute for Climate and Satellites at the University of Maryland and lead author.

The most vulnerable areas of the global ocean are being hit with a double whammy of sorts. In these areas, deep ocean waters that are naturally rich in carbon dioxide are upwelling and mixing with surface waters that are absorbing carbon dioxide from the atmosphere. The carbon dioxide from the atmosphere is coming primarily from human-caused fossil fuel emissions.

“When oyster larvae are born they must draw on the energy in their yolk to build their aragonite shells to protect themselves from predators and grow into healthy adults,” said Feely. In waters depleted of carbonate ions, young oysters must expend more energy to build their shell and may not survive. This has significant consequences for the seafood industry.”

Read the original post: http://www.eurekalert.org/

Climate change will irreversibly force key ocean bacteria into overdrive

Researchers Say Ocean Acidification Poses Legitimate Extinction Threat to West Coast Shellfish

— Posted with permission of SEAFOODNEWS.COM. Please do not republish without their permission. —

SEAFOODNEWS.COM [San Francisco Chronicle] by Lizzie Johnson – August 21, 2015

Long before scientists and shellfish companies were aware of what was happening, a silent killer began devastating California’s oyster industry.

About 10 years ago, baby oysters, or spat, began to die at an alarming rate. Farms along the West Coast lost more than half of their bivalves before they reached maturity, creating a shortage of seed. That deficit hit Hog Island Oyster Co. in Marshall especially hard.

So owners Terry Sawyer and John Finger began collaborating with UC Davis’ Bodega Marine Laboratory to figure out what was plaguing the water in Tomales Bay, their backyard.

After more than two years of tests, they have a better understanding of the condition afflicting West Coast oysters, mussels and clams. But there is trouble ahead for California’s shellfish industry as it faces the threat of species extinction.

“We are talking about something that’s going to happen in my lifetime and my children’s lifetime,” said Tessa Hill, an associate professor of geology at UC Davis. “We are going to see dramatic changes in terms of what animals can be successful on the California coast because of ocean acidification.”

That culprit, ocean acidification, is the caustic cousin of climate change, and it shifts the chemistry of ocean water, making it harder for oysters to grow. That’s because about 30 percent of the carbon dioxide released into the atmosphere is absorbed by the ocean, causing pH levels to plummet and making the water more acidic. The more pollution in the air, the more carbon dioxide the ocean absorbs.

Larval stage stunted

The hostile conditions stunt the growth of oysters in the larval stage, making it difficult to build their fragile calcium carbonate shells. If acidification doesn’t kill them outright, an increased susceptibility to disease and predators often will. The stress also weakens many small oysters, so it takes them longer to reach reproductive age.

“It’s definitely scary,” said Zane Finger, who runs the Marshall oyster farm for his father, John. “If you’re doing any kind of job that depends on the environment, whether it’s farming on land or farming in the water, it can be uncertain. Things are changing, and it makes me nervous about the future of this business.”

Oyster growers in Oregon were the first to sound the alarm 10 years ago on ocean acidification. Whiskey Creek Shellfish Hatchery, based in Oregon’s Netarts Bay, and Oregon State University were among the first to work together and publish research on the phenomenon. They established the link between acidification and the collapse of oyster seed production.

Dire prediction

“It was one of the first times that we have been able to show how ocean acidification affects oyster larval development at a critical life stage,” OSU chemical oceanographer Burke Hales said in a statement. He was a co-author on one of the first studies in Oregon. “The predicted rise of atmospheric carbon dioxide in the next two to three decades may push oyster larval growth past the break-even point in terms of production.”

And in 2010, a mix of scientists and industry partners formed the California Current Acidification Network (C-CAN), which works for more research on acidification. UC Davis and Hog Island, both members, have helped expand research along the coast. The relationship has helped Hog Island prepare for future water conditions and allowed the university to conduct research on the link between climate change and acidification.

For the first two years of the company’s collaboration with Hill, data were collected only once a month from a buoy in the estuary. Then the federal Central and Northern California Ocean Observing System (which goes by the mile-long acronym of CeNCOOS), offered to upgrade the system.

Now, it’s a round-the-clock operation that gives minute-by-minute data on water conditions. Hill runs a small lab tucked in the back of a shed at Hog Island’s Marshall oyster farm. The structure is damp and filled with loudly whining equipment. Tubes pump seawater directly in from the bay so the team can closely monitor changes in acidity, salinity, temperature and oxygen.

‘Stressful for oysters’

“You can get up in the morning and look at the charts and say, ‘Oh, the water is stressful for the oysters today,’” Hill said, pointing to a zigzagging line on the computer screen. “It gives them real-time information and a big picture of what’s happening in the bay.”

They’ve learned that the high acidity in the water is related to seasonal upwelling, or when the wind pushes surface water offshore, allowing the deeper, more acidic water to rise up. For now, hatcheries can grow spat during spring and summer, considered the off seasons. But by 2030, upwellings are expected to last longer, and by 2050, they could occur year-round, Hill said.

“The rate of change is something that we have never seen before as a planet,” Sawyer said. “And it’s measurable; you can’t argue with that. We have the data. We should pay attention to it now, immediately, and not later.”

High mortality rate

The mortality rate for baby oysters is still high — anywhere from 50 to 100 percent. But oyster companies have learned to compensate for it by growing more spat in different locations. They’ve also put a quota on the amount of shellfish customers can buy. Diversifying will hopefully prevent another shortage like the one that hit from 2007 to 2010.

Sawyer and John Finger are planning to expand the company’s aquaculture operation. Within the next two years, they will open a $1.5 million oyster hatchery in Humboldt Bay. It will provide seeds to grow in Tomales Bay and, eventually, harvest some of its own oysters as well. Permits have been approved, and cultivation will start later this year.

A day on the farm

For now, operations at Hog Island Oyster Co.’s Marshall farm remain the same. Most mornings, workers slide on their rubber waders and guide a flat-bottomed boat onto the water. Then they slosh to the oyster racks nestled on the muddy floor, dragging them to the surface with long hooks. The smell of musty water and saltwater fills the air as they work.

Soon — and Sawyer hopes for a long time — those oysters will make their way to someone’s plate.

“I care about this on so many levels,” he said. “From a farming point of view, from business, from caring about my kids and the future generations who will have to deal with this. We live in a pretty amazing world, and I would like to preserve that as much as possible.”

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Chemical clues in fossil shells may help us understand today’s ocean acidification

By: Brendan Bane

As atmospheric CO2 levels rise, so too do those in the sea, leading to ocean acidification that outpaces that of any other time in tens of millions of years. Some effects of ocean acidification are imminent, like the fact that calcified organisms such as corals and shellfish will have access to less and less of the chemical components they need to build their shells and skeletons. Other outcomes are less clear, and scientists wanting to predict what may come of our quickly acidifying waters are looking to past climatic events that were similar to our own.

One such event, the Paleo-Eocene Thermal Maximum (PETM), which occurred 56 million years ago, is likely our closest analog to modern ocean acidification. Researchers who refer to the PETM as a case study have long suspected that ancient waters acidified then, but until recently, they never had physical evidence of it actually happening. Then just this past year, researchers uncovered the PETM’s chemical chronology encrypted in the shells of fossilized plankton, called foraminifera, and learned that the two timelines aren’t entirely similar; today’s surface ocean is acidifying ten times faster than it did during the PETM. Their findings were published in Paleoceanography in June, 2014.

Penman (the lead author) offered this image of himself (center), Richard Norris (Scripps) and Pincelli Hull (Yale) inspecting sediment cores from the PETM while aboard a scientific drilling vessel.
Penman (the lead author) offered this image of himself (center), Richard Norris (Scripps) and Pincelli Hull (Yale) inspecting sediment cores from the PETM while aboard a scientific drilling vessel. Photo credit Donald Penman.
“While foraminifera are alive, they incorporate the chemistry of the water into their shells,” said Bärbel Hönisch, associate professor of earth and environmental sciences at Columbia University and coauthor of the study. “When they die, they take that information with them into the sediment.”

Hönisch and several other scientists analyzed the chemical composition of fossilized foraminifera embedded in “nannofossil ooze,” a section of rock particularly rich with tiny fossilized organisms, which they drilled out of sub-ocean sediment near Japan.

Foraminifera, like coral and shellfish, pull carbonate ions from the surrounding seawater to build their shells. In a way, the chemical composition of these shells acts as a snapshot of the chemical composition of the water the foraminifer lived in. When water grows increasingly acidic, foraminifera replace whole carbonate molecules with borate molecules. When the scientists of this study inspected the boron composition of shells from plankton that died during the PETM, they learned not only how acidic the ocean was at the time, but also how quickly its chemistry shifted and how long it stayed that way.

“Acidification during the PETM was relatively rapid,” said oceanographer Richard Zeebe of the University of Hawaii at Manoa, another coauthor of the study, “but it was also sustained. The whole event took a very long time.” A massive surge in atmospheric carbon, its cause still unknown, warmed the globe by four to eight degrees and dropped the ocean’s pH by about 100 percent. Conditions remained that way for approximately 70,000 years. These environmental changes triggered many biological ones. Seafloor-dwelling foraminifera suffered mass extinction while another type of tiny aquatic organism, dinoflagellates, thrived and expanded.

Foraminifera like the one pictured above record their environment’s chemistry in calcium carbonate shells, essentially leaving a trail of chemical breadcrumbs for future investigators. Photo by Howard Spero.
Foraminifera like the one pictured above record their environment’s chemistry in calcium carbonate shells, essentially leaving a trail of chemical breadcrumbs for future investigators. Photo by Howard Spero.
Although the PETM ocean did acidify quickly, it happened ten times slower than what’s happening today. Our ocean’s pH has dropped from 8.2 to 8.1 in the last 150 years, an amount that took a few thousand years in the PETM. Scientists predict the drop will only continue, with the seas reaching a pH of 7.8 to 7.9 by 2100. That change was and continues to be fueled by manmade carbon being pumped into the atmosphere and subsequently absorbed by the ocean.

In understanding how to compare the two events and what outcomes will emerge from modern acidification, rate is key.

“In any aspect of environmental change, particularly global change, rate matters” said lead author Donald Penman of the University of California Santa Cruz. Natural buffers like deep seawater mixing likely mitigated acidification during the PETM. But those same buffers will surely be outpaced by today’s heightened rate. “If you put carbon dioxide into the ocean faster than its natural processes can deal with it,” Penman said, “then they don’t do you any good.”

Marine animals will also be challenged by the speed at which their environment is changing. “We know that organisms and ecosystems can adapt and evolve to slow changes as they have throughout earth’s history,” Penman said. “However, when you invoke the same change over a shorter time, then you can outstrip organisms’ ability to evolve with that change. Species go extinct, and marine ecosystems change dramatically, perhaps irrecoverably.”

The researchers noticed that extinctions occurred during the PETM even at a pH change rate of 0.1 per thousands of years – which may not bode well for today’s foraminifera.

“The fact that some organisms went extinct during the PETM puts our current activities in perspective,” said Hönisch. “If the organisms died then, it is even more likely that some organisms will die now.”

With a clearer picture of the PETM painted, researchers can begin to draw more detailed analogies between the two events, and hopefully catch any drastic environmental changes before they surprise us.

“Now that we have [ocean acidification during PETM] quantified,” Penman said, “we can begin to make calculations of how much and how quickly carbon was emitted during the PETM. This will help us disentangle what sources of carbon and feedbacks were in operation during the PETM, and whether or not they are something we need to worry about in the future.”

Penman (the lead author) offered this image of himself (center), Richard Norris (Scripps) and Pincelli Hull (Yale) inspecting sediment cores from the PETM while aboard a scientific drilling vessel. Photo credit Donald Penman.

Foraminifera like the one pictured above record their environment’s chemistry in calcium carbonate shells, essentially leaving a trail of chemical breadcrumbs for future investigators. Photo by Howard Spero.

Citations:
Penman, D. E., Hönisch, B., Zeebe, R. E., Thomas, E., & Zachos, J. C. (2014). Rapid and sustained surface ocean acidification during the Paleocene‐Eocene Thermal Maximum. Paleoceanography.
Hönisch, B., Ridgwell, A., Schmidt, D. N., Thomas, E., Gibbs, S. J., Sluijs, A., … & Williams, B. (2012). The geological record of ocean acidification. science, 335(6072), 1058-1063.

Read the original post Mongabay.com.

Why isn’t anyone talking about Ocean Acidification?

Climate change is not the only outcome of increased greenhouse gas concentrations. The oceans have absorbed a lot of the excess carbon in the atmosphere, reducing the impacts of climate change to date, but at a cost. Higher concentrations of carbon dioxide (CO2) in the atmosphere have led to an increase in acidity of ocean water, a process known as ocean acidification. The process of acidification is laid out by Cheryl Logan in a user-friendly 2010 summary in the journal Bioscience.

Ocean acidification occurs when CO2 dissolves in ocean water, undergoing a chemical reaction that produces carbonic acid. The rate of this reaction is completely predictable and as a result the progression of acidification as CO2 levels increase is completely predictable. Unlike climate change, ocean acidification is not controversial at all—basically nobody disputes that it is happening—and happening rapidly.

As Logan explains, acidity is measured through the concentration of hydrogen ions—called the pH scale, for power of hydrogen—more hydrogen equals greater acidity. Since the late 19th century, the concentration of hydrogen ions in the ocean has increased by 30%, and that will increase another 150% by 2100, according to common emissions projections.

That is a massive change to ocean chemistry in a short amount of time, and many of the ocean’s inhabitants are struggling to adapt. The shells of many marine organisms are made of calcium carbonate, which is highly susceptible to acid. Logan explains how some organisms are starting to have trouble forming new shells, and in extreme cases, existing shells are getting thinner.

Just in case the plight of a few snails seems like a relatively minor concern, the issue goes well beyond snails. Corals, sea urchins, many species of plankton- organisms crucial to marine habitats and food webs- all rely on calcium carbonate as part of their structure. Some research even suggests that acidification can disrupt the ability of plants to perform photosynthesis. As marine organisms are responsible for much of the Earth’s oxygen production, this might one day threaten our very survival.

Acidification has the potential to completely disrupt the ocean’s—and perhaps even the planet’s—ecosystem before climate change has a chance to do so. Despite the urgency Logan describes, the American public is largely unaware of the issue. Public awareness notwithstanding, the solution to ocean acidification is straightforward: burn less carbon. Efforts to curb the climate change will address acidification as well, but progress is slow. It is astounding that such a key issue, one that might genuinely threaten our survival as a species, is still so little-known.

JSTOR Citations:

A Review of Ocean Acidification and America’s Response
Cheryl A. Logan
BioScience
Vol. 60, No. 10 (November 2010), pp. 819-828
Published by: Oxford University Press

Marine and Coastal Science: Will Ocean Acidification Erode the Base of the Food Web?
Carol Potera
Environmental Health Perspectives
Vol. 118, No. 4 (APRIL 2010), p. A157
Published by: The National Institute of Environmental Health Sciences (NIEHS)

View original post: JSTOR|Daily

Is Ocean Acidification Affecting Squid?

A key animal in the marine food web may be vulnerable

By Daniel Cojanu, Elise Hugus :: Originally published online September 26, 2014

Click below to begin video — or view the original video here. Produced by Woods Hole Oceanographic Institution.

Bluefin Tuna Are Showing Up in the Arctic—and That’s Not Good News

By | Takepart.com September 15, 2014 4:30 PM Takepart.com

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When you throw a net into the ocean, you never know what you’ll pull out.

That was the case for researchers cruising the freezing Arctic waters off Greenland in August 2012 in search of mackerel to see if there were enough of the fish to support a commercial fishery. In one haul, three endangered bluefin tuna, each weighing roughly 220 pounds, were pulled onto the ship’s deck amid six metric tons of mackerel.

“It was a bit surprising,” said Brian MacKenzie, a marine ecologist at the National Institute for Aquatic Resources at the Technical University of Denmark. The research ship was sailing in the Denmark Strait, between Greenland and Iceland, where water temperatures have historically been too cold for bluefin tuna.

More bluefin tuna have been caught off eastern Greenland since then. From June to the end of August of this year, Greenland fishing vessels caught 21 tuna—in addition to 65,000 metric tons of mackerel, according to Greenland Today.

The ever warmer Arctic waters could have profound impacts on how fisheries and food webs are managed and conserved in the future as tropical and Mediterranean species migrate into what were once colder waters.

With Arctic waters warming and attracting bluefin tuna, Iceland and Norway in 2014 implemented commercial quotas for the prized fish. “It’s small, only 30 [metric] tons each,” said MacKenzie. “But it indicates that the distribution is really changing.”

“Climate change is really challenging political and diplomatic relationships,” said Nick Dulvy, a professor of marine biodiversity and conservation at Simon Fraser University, in Burnaby, British Columbia. “Species names will change, and if your quotas are tied to a species name, that’s a problem for the fishery,”

In 2009, after mackerel had spread to the coastlines of Iceland and the Faroe Islands, Iceland set itself a mackerel quota of 112,000 metric tons. That angered the European Union, and conservationists worried that stocks of the humble fish would suffer.

MacKenzie and his colleagues analyzed the water temperatures east of Greenland using satellite imagery, oceanographic buoys, and measurements from ships. They found warm water had spread from the southeast Atlantic toward eastern Greenland. August temperatures in 2010 and 2012 were warmer than any other time since 1870. They recently published their findings in the journal Global Change Biology.

In fact, between 1985 and 1994 and 2007 and 2012, waters with temperatures greater than 11 degrees Celsius in the Denmark Strait and Irminger Sea has increased by 278,000 square miles—an area larger than Texas. “It’s only in the past two to three years that we can see that the temperatures of the waters east of Greenland have gotten above 10 degrees Celsius in the summer time,” MacKenzie said.

Not only can bluefin tuna tolerate warming Arctic waters more easily, their prey can too.

Mackerel have been increasing their reach since the mid-2000s, according to MacKenzie, moving from the European continental shelf out toward the Faroe Islands and on to Iceland.

The oily fish is a preferred sustenance for tuna, which usually only search for prey in waters where the minimum surface temperature is above 11 degrees Celsius, said MacKenzie. That the tuna were brought in with a load of mackerel in 2012 suggests there was a school of tuna hunting the smaller fish, he said.

Finding bluefin tuna off Greenland is more evidence that climate change is shuffling the species swimming about the world’s oceans. Fish generally found in warmer waters are being spotted in regions formerly filled by cold-tolerant species, or are expanding their range. Mackerel have moved into the waters south of Iceland, and anchovy now swim the North Sea.

“Around Denmark, we’re seeing species that 15 to 20 years ago would have been extremely rare, such as anchovy and red mullet,” said MacKenzie.

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Tags: bluefin tuna, ocean acidification

Sep 9 2014

UN warns on ocean acidification as GHG levels soar

Carbon dioxide emissions in 2013 were largest on record since 1984, says World Meteorological Organization 

Shellfish are vulnerable to acidification, as acid in waters prevents species developing calcium shells (Pic: NOAA)

By Ed King

Current levels of ocean acidification are “unprecedented” and directly linked to rising emissions of carbon dioxide, according to the UN’s World Meteorological Organization (WMO). 

In a greenhouse gas analysis of 2013, released on Tuesday, it said concentrations of CO2 in the air had risen more than any other year since 1984. Methane and nitrous oxide levels also rose.

Carbon dioxide levels in the atmosphere are now 142% higher than 1750, before the industrial revolution.

And the WMO said data showed the warming effect on the world’s climate due to greenhouse gases, known as radiative forcing, had risen 34% between 1990 and 2013.

“Carbon dioxide remains in the atmosphere for many hundreds of years and in the ocean for even longer,” said WMO secretary general Michel Jarraud.

“Past, present and future CO2 emissions will have a cumulative impact on both global warming and ocean acidification. The laws of physics are non-negotiable.”

Jarraud added the latest data should be used as a “scientific base for decision-making”.

World leaders are primed to meet in New York in two weeks for a UN summit to discuss options to reduce emissions of climate warming gases.

This report is the latest evidence of the levels of atmospheric gases burning fossil fuels has released.

A leaked draft of the UN’s IPCC climate science panel syntheses report, due out in November, stressed that “human influence on the climate system is clear”.

Earlier this year the Mauna Loa observatory in Hawaii recorded for the first time in recorded history that concentrations of carbon dioxide in the atmosphere had passed 400 parts per million (ppm).

Report: Alaska fisheries hit by rising acidifiction levels

Equally concerning, WMO scientists said the ability of the biosphere to absorb rising carbon levels had diminished, leaving the oceans to compensate.

“The ocean cushions the increase in CO2 that would otherwise occur in the atmosphere, but with far-reaching impacts,” it said in a press release.

“The current rate of ocean acidification appears unprecedented at least over the last 300 million years, according to an analysis in the report.”

Caused when the oceans suck in CO2, acidification is likely to lead to the decline of corals, algae, molluscs and some plankton, say scientists.

The ocean currently absorbs around a fourth of manmade CO2 emissions. The WMO said if emissions continue to rise, acidification is likely to accelerate until the 2050s.

Earlier this year the IPCC said ocean warming and acidification linked to rising CO2 levels would undermine food production and threaten the world’s poorest people.

Wendy Watson-Wright, executive secretary of the Intergovernmental Oceanographic Commission of UNESCO welcomed the WMO’s focus on oceans in its report.

“The inclusion of a section on ocean acidification in this issue of WMO’s greenhouse gas bulletin is appropriate and needed,” she said.

“It is high time the ocean, as the primary driver of the planet’s climate and attenuator of climate change, becomes a central part of climate change discussions.”

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Read the original post at www.rtc.org:

http://www.rtcc.org/2014/09/09/un-warns-on-ocean-acidification-as-ghg-levels-soar/

Permalink | Categories Research, View from the Ocean on September 9, 2014 by FishingNews | Comments Off on UN warns on ocean acidification as GHG levels soar
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