At the end of experiments (~20 days) larvae of the hard clam, bay scallop, and Eastern oyster that were raised in seawater with high carbon dioxide concentration (right column) were smaller and later to develop than larvae raised in seawater with carbon dioxide concentration matching current ocean levels (left column.) Credit: Stephanie Talmage

Relatively minor increases in ocean acidity brought about by high levels of carbon dioxide have significant detrimental effects on the growth, development, and survival of hard clams, bay scallops, and Eastern oysters, according to researchers at Stony Brook University’s School of Marine and Atmospheric Sciences. In one of the first studies looking at the effect of ocean acidification on shellfish, Stephanie Talmage, PhD candidate, and Professor Chris Gobler showed that the larval stages of these shellfish species are extremely sensitive to enhanced levels of carbon dioxide in seawater. Their work will be published in the November issue of the journal Limnology and Oceanography and is now online at http://www.aslo.org/lo/toc/vol_54/issue_6/index.html. “In recent decades, we have seen our oceans threatened by overfishing, harmful algal blooms, and warming. Our findings suggest ocean acidification poses an equally serious risk to our ocean resources,” said Gobler. During the past century the oceans absorbed nearly half of atmospheric carbon dioxide derived from human activities such as burning fossil fuels. As the ocean absorbs carbon dioxide it becomes more acidic and has a lower concentration of carbonate, which shell-making organisms use to produce their calcium carbonate structures, such as the shells of shellfish. In lab experiments, Talmage and Gobler examined the growth and survivorship of larvae from three species of commercially and ecologically valuable shellfish. They raised the larvae in containers bubbled with different levels of carbon dioxide in the range of concentrations that are projected to occur in the oceans during the 21st century and beyond. Under carbon dioxide concentrations estimated to occur later this century, clam and scallop larvae showed a more than 50% decline in survival. These larvae were also smaller and took longer to develop into the juvenile stage. Oysters also grew more slowly at this level of carbon dioxide, but their survival was only diminished at carbon dioxide levels expected next century. …

Ocean acidification may contribute to global shellfish decline via Ocean Acidification