Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life

Might a penguin's next meal be affected by the exhaust from your tailpipe? The answer may be yes, when you add your exhaust fumes to the total amount of carbon dioxide lofted into the atmosphere by humans since the industrial revolution. One-third of that carbon dioxide is absorbed by the world's oceans, making them more acidic and affecting marine life.

A UC Santa Barbara marine scientist and a team of 18 other researchers have reported results of the broadest worldwide study of ocean acidification to date. Acidification is known to be a direct result of the increasing amount of greenhouse gas emissions. The scientists used sensors developed at Scripps Institution of Oceanography at UC San Diego to measure the acidity of 15 ocean locations, including seawater in the Antarctic, and in temperate and tropical waters.

As oceans become more acidic, with a lower pH, marine organisms are stressed and entire ecosystems are affected, according to the scientists. Gretchen E. Hofmann, an eco-physiologist and professor in UCSB's Department of Ecology, Evolution & Marine Biology, is lead author of the recent article in PLoS ONE that describes the research.

"We were able to illustrate how parts of the world's oceans currently have different pH, and thus how they might respond to climate changes in the future," said Hofmann. "The sensors allowed us to capture that." The sensors recorded at least 30 days of continuous pH values in each area of the study.

Since the beginning of the industrial revolution, human activities have accelerated the release of carbon dioxide into the atmosphere as carbon dioxide mixes with water. The two molecules combine to become carbonic acid, making seawater more acidic. As billions of molecules combine and go through this process, the overall pH of the oceans decreases, causing ocean acidification.

Acidification limits the amount of carbonate forms that are needed by marine invertebrates, such as coral, urchins, snails, and shellfish, to make their skeletons. As the concentration of carbonates decreases in acidified water, it is harder to make a shell. And, the structures of some organisms may dissolve when water chemistry becomes too unfavorable.

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