Study: Ocean acidification putting marine life at risk - San Jose Mercury NewsWhen carbon dioxide emissions from cars or power plants are absorbed by the oceans, it changes seawater chemistry and makes it more acidic, a process called "ocean acidification." Increasing ocean acidity makes it difficult for organisms that construct their shells and exoskeletons out of calcium carbonate, such as mussels and oysters, to continue to build these protective layers. In high enough concentrations, carbon dioxide can even cause these shells and skeletons to dissolve entirely.Tide pools along California's rocky coast are isolated from the open ocean during low tides. During the daytime, photosynthesis—the mechanism by which plants convert the Sun's energy and atmospheric carbon dioxide into sugar, giving off oxygen in the process—takes up carbon dioxide from the seawater and acts to reverse ocean acidification's effects. However, at night, plants and animals respire just like we do, taking up oxygen and releasing carbon dioxide. This adds carbon dioxide to the seawater and exacerbates effects of ocean acidification, causing the increasing risk to calcifying organisms.
A new study, based on the most extensive set of measurements ever made in tidepools, 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.