Eastern Oysters and Ocean Acidification: Does Family Impact Tolerance?

Eastern oysters (Crassostrea virginica) are a bivalve species in Virginia and the Chesapeake Bay that play an important role in their aquatic ecosystems and are an important species in aquaculture. Rising problems caused by climate change, such as ocean acidification (OA), could threaten natural populations and the success of the aquaculture industry. One solution to the threat of OA may be selective breeding of Eastern oysters for increased tolerance of OA, but there is currently limited research to inform the potential of this strategy. The first step towards evaluating the potential of this solution involves determining if oysters with different genetics respond differently to OA. This project looked at two genetically different families of Eastern oysters produced from broodstock bred for high performance in either high salinity or low salinity conditions to see if their tolerance of OA conditions differed. Juvenile oysters from each family were exposed to either acidified or control pH conditions (pH 7.3 and 7.8, respectively) for two weeks after which physiological responses were measured. The individual and interactive impacts of treatment and family on respiration rates, calcification rates, energy stores, oxidative stress, and total protein content were assessed. Family had an impact on response to OA for just total protein content out of the parameters measured, with oyster seed from the low salinity family having higher total protein content at acidified conditions than oysters from the high salinity family, but similar total protein between families at control conditions. Therefore, some traits related to OA tolerance may be influenced by family and thus could be selected for if they are heritable. However, we generally observed negative impacts of OA on oyster seed regardless of family, such as lower calcification rates and evidence of oxidative stress. Further research should examine if traits related to OA tolerance are heritable and whether there are families with more robust physiological tolerance of OA impacts.