Increased Ocean Acidification In Alaska

The uptake of anthropogenic carbon since colonial times has resulted in an average decrease in seawater pH of 0.1 units. Increasing atmospheric CO2 concentrations will exacerbate this acidification as dissolved CO2 levels (and consequently H2CO3 levels) rise. Projections based on the IPCC Special Report on Emissions Scenarios (SRES) show a reduction in average global surface ocean pH of between 0.14 and 0.35 units over the 21st century, which would be a doubling of H+ ions. (Fields et al. 1993; IPCC 2007) New research out of the University of Alaska finds that "ocean acidification is likely more severe and is happening more rapidly in Alaska than in tropical waters."
Via ScienceDaily.com
Increased Ocean Acidification In Alaska Waters, New Findings Show

The same things that make Alaska's marine waters among the most productive in the world may also make them the most vulnerable to ocean acidification. According to new findings by a University of Alaska Fairbanks scientist, Alaska's oceans are becoming increasingly acidic, which could damage Alaska's king crab and salmon fisheries.

Read the entire article at Science Daily.

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Modulation of Ocean Acidification

Via PNAS:
Reasearch suggests that acidification rate of the oceans is modulated by physical and biogeochemical processes which must be considered "when designing and interpreting ocean pH monitoring efforts and predictive models."

Physical and biogeochemical modulation of ocean acidification in the central North Pacific

Here we report the results of nearly 20 years of time-series measurements of seawater pH and associated parameters at Station ALOHA in the central North Pacific Ocean near Hawaii. We document a significant long-term decreasing trend of −0.0019 ± 0.0002 y−1 in surface pH, which is indistinguishable from the rate of acidification expected from equilibration with the atmosphere. Superimposed upon this trend is a strong seasonal pH cycle driven by temperature, mixing, and net photosynthetic CO2 assimilation.

Read the Open Access article at PNAS.


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Elevated CO2 levels cause abnormally large otoliths in fish

A study out of Scripps, featured in this week's Science, reports that elevated levels of dissolved carbon dioxide cause the growth of abnormally large otoliths in white seabass.

Rising carbon dioxide levels in the ocean have been shown to adversely affect shell-forming creatures and corals, and now a new study by researchers at Scripps Institution of Oceanography at UC San Diego has shown for the first time that CO2 can impact a fundamental bodily structure in fish.

A brief paper published in the June 26 issue of the journal Science describes experiments in which fish that were exposed to high levels of carbon dioxide experienced abnormally large growth in their otoliths, or ear bones. Otoliths serve a vital function in fish by helping them sense orientation and acceleration.

Read the press release here.
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Is regulation on ocean acidification on the horizon?

Noreen Parks writes in Environmental Science and Technology:

With mounting evidence that ocean waters worldwide are turning more acidic, scientists have issued ever more urgent pleas for policy makers to recognize that this phenomenon is a direct and real consequence of rising levels of atmospheric CO2. Researchers warn that as ocean pH falls, the capacities of calcifying marine organisms to build shells and skeletons will be severely reduced, in all likelihood causing widespread impacts on marine ecosystems. In June 2009, a statement endorsed by 70 national science academies emphasized that the issue must be on the agenda at the upcoming global climate talks in Copenhagen. “To avoid substantial damage to ocean ecosystems, deep and rapid reductions of global CO2 emissions by at least 50% by 2050, and much more thereafter, are needed,” the statement warned.

Read the full article here.
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Rising acidity levels could trigger shellfish revenue declines, job losses

Via The Woods Hole Oceanographic Institution:
Changes in ocean chemistry — a consequence of increased carbon dioxide (CO2) emissions from human industrial activity — could cause U.S. shellfish revenues to drop significantly in the next 50 years, according to a new study by researchers at the Woods Hole Oceanographic Institution (WHOI).

Intensive burning of fossil fuels and deforestation over the last two centuries have increased CO2 levels in the atmosphere by almost 40 percent. The oceans have absorbed about one-third of all human-generated carbon emissions, but the buildup of CO2 in the ocean is pushing surface waters toward more acidic conditions.

This “ocean acidification” creates a corrosive environment for marine organisms such as corals, marine plankton, and shellfish that build carbonate shells or skeletons. Mollusks — including mussels and oysters, which support valuable marine fisheries — are particularly sensitive to these changes.


In a case study of U.S. commercial fishery revenues published in the June issue of Environmental Research Letters, WHOI scientists Sarah Cooley and Scott Doney calculated the possible economic effects of ocean acidification over the next 50 years using atmospheric CO2 trajectories from the Intergovernmental Panel on Climate Change and laboratory studies of acidification’s effects on shell-forming marine organisms, focusing especially on mollusks.

Mollusk sales by fishermen currently generate about $750 million per year — nearly 20 percent of total U.S. fisheries revenue. The study assumed that mollusks harvests in the U.S. would drop 10 to 25 percent in 50 years’ time as a result of increasing acidity levels, which would decrease these mollusk sales by $75 to $187 million dollars annually.

“Losses in primary revenue from commercial mollusk harvests—or the money that fisherman receive for their catch—could add up to as much as $1.4 billion by 2060,” said Cooley.

Reduced harvests of mollusks, as well as losses of predatory fish and other species that depend on mollusks for food, could lead to economic hardships for fishing communities.

“Ocean acidification will impact the millions of people that depend on seafood and other ocean resources for their livelihoods,” said Doney. “Losses of crustaceans, bivalves, their predators, and their habitat — in the case of reef-associated fish communities — would particularly injure societies that depend heavily on consumption and export of marine resources.”

Because changes in seawater chemistry are already apparent and will grow over the next few decades, Cooley and Doney suggest measures that focus on adaptation to future CO2 increases to lessen the impact on marine ecosystems, such as flexible fishery management plans and support for fishing communities.

“Limiting nutrient runoff from land helps coastal ecosystems stay healthy,” said Cooley. “Also fishing rules can be adjusted to reduce pressure on valuable species; fisheries managers may set up more marine protected areas, or they may encourage development of new fisheries.”

This research was supported by grants from the National Science Foundation and Woods Hole Oceanographic Institution.

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Ocean Acidification

The uptake of anthropogenic carbon since colonial times has resulted in an average decrease in seawater pH of 0.1 units. Increasing atmospheric CO2 concentrations will exacerbate this acidification as dissolved CO2 levels (and consequently H2CO3 levels) rise. Projections based on the IPCC Special Report on Emissions Scenarios (SRES) show a reduction in average global surface ocean pH of between 0.14 and 0.35 units over the 21st century, which would be a doubling of H+ ions. (Fields et al. 1993; IPCC 2007)

Fields, P. A., J. B. Graham, R. H. Rosenblatt, and G. N. Somero. 1993. Effects of expected global climate change on marine faunas. Twenty years of TREE - part I 8:361-367.

IPCC. 2007. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change in M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E.Hanson, editors, Cambridge, UK. Read more!