Award: OCE-0927255

NSF AWARD OCE-0927255 OCEAN ACIDIFICATION IN A CALIFORNIA UPWELLING ZONE: A SENTINEL SITE FOR IMPACTS ON OPEN-COAST AND ESTUARINE FOUNDATION SPECIES PROJECT OUTCOMES The oceans have absorbed about one third of the carbon dioxide (CO2) produced by humans since the early 1800Æs. This uptake of CO2 changes the chemistry of seawater by making it more acidic, which in turn can make it more difficult for organisms to produce their shells and skeletons and maintain the proper chemical balance within their tissues. Along the west coast of the U.S., prevailing winds blow in such a way as to push surface waters offshore. In response, deeper waters "upwell" to replace them. These deeper waters are naturally high in carbon dioxide. As a consequence, conditions along the California, Oregon, and Washington coasts intrinsically experience more acidic seawater, onto which the human-derived effects of CO2 are then layered. These areas may therefore provide early insight into how marine systems in general will respond to elevated seawater CO2. This project addressed impacts of ocean acidification on several critical species that live along the coast of California. In particular, it explored how elevated seawater CO2 influences growth and survival of Olympia oysters and California mussels, focusing on the vulnerable microscopic larval stages of these creatures which live for a time in the plankton. Resultant research revealed declines in the sizes of the shells of larval mussels, dramatic reductions in their tissue mass, and impaired shell strength. In oyster larvae, ocean acidification causes decreases in growth. Such decreases also become magnified once the planktonic larvae settle on the seafloor and become juveniles. This latter effect is analogous to how environmental conditions in early human life can stunt growth and impair health years later. Accompanying tests showed that impacts of remarkably brief exposures of oysters to ocean acidification persist for months under natural field conditions, and do not attenuate over time even in benign habitats. Similarly, impacts are not fully overcome by giving oysters extra food. Additional experiments conducted as part of the project also demonstrate effects of elevated seawater CO2 on limpets, on predator-prey interactions between oysters and the snails that consume them, on growth of sea urchin larvae, and on respiration rates of larval crabs. In the case of urchin larvae, there are hints that sufficient genetic differences exist among populations to allow certain strains to differentially succeed in the face of elevated seawater CO2. Such strains may have the potential to offset population declines. Whether other species might have the capacity to respond similarly remains unclear. The project contributed to the advancement of several graduate students and postdoctoral researchers who were supported by the grant, led to the development of an academic-industry partnership with a local oyster grower, and was covered by the popular media in multiple articles, radio broadcasts, and videos. Last Modified: 09/11/2013 Submitted by: Brian P Gaylord