Ocean Acidification Affects Larval and Juvenile Growth in the Olympia Oyster, Ostrea lurida
Forsch, Margaux Alexandria
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Increasing atmospheric carbon dioxide has led to a reduction in ocean pH and carbonate saturation, making it difficult for many calcifying marine organisms to secrete their shells. We investigated the effects of.ocean acidification on larval and juvenile growth in the native West Coast Olympia oyster (Ostrea lurida). Adult oysters were collected from an estuary in Tomales Bay, California known to have a native population of O. lurida. Larvae and juveniles from four independent parental groups were reared in the laboratory under three carbon dioxide concentrations (380,540, and 970 ppm) representing present-day atmospheric concentrations and two projected scenarios for the year 2100. Oysters were exposed to treatment conditions continuously for 19 days, encompassing larval release and development, followed by settlement and early juvenile life. After nine days of exposure, larvae in the .970 ppm treatment (pH = 7.78) had grown 16% less in shell area than larvae held under control conditions at 380 ppm (pH = 7.99). These effects continued into the benthic phase; shell size at settlement was 7% smaller in the 970 ppm treatment than in control conditions. Moreover, the magnitude of these negative effects increased during the early juvenile phase; eight days after settlement, juveniles in the 970 ppm treatment. had grown 41 % less in shell size than juveniles held under control conditions. There was significant variation in growth among parental groups only on day five of the experiment. Thereafter, there was no evidence of intraspecific growth variation in response to the C02 treatments. Because larval and juvenile phases can be critical population bottlenecks for oysters and other marine invertebrates, our results strongly suggest that the Olympia oyster may be particularly vulnerable to the effects of ocean acidification.