Abstract
Estuaries are naturally dynamic systems facing increasing variability of water quality conditions due to increased rainfall and snow melt caused by climate change, coastal land loss, and river management. Across the northern Gulf of Mexico, one ecologically and economically important species residing in estuaries is Crassostrea virginica, the eastern oyster. Although highly tolerant to a wide range of salinities and salinity variation, more frequent exposure of oysters to extreme low salinity (< 5) may impact overall population sustainability within some estuaries. This study assesses previously unexamined populations of C. virginica from low salinity areas of the Louisiana coast for population-specific tolerance to low salinities (< 5). Spat (< 25 mm) from four C. virginica populations were grown in an off-bottom long-line system in both a high salinity (10-15) (Grand Isle, LA) and a low salinity (< 6) (Cocodrie, LA) environment. Oysters were set out in December 2019 and growth and mortality are being tracked for a 12-month period. Upon completion of sampling, population specific growth, mortality, condition and dermo infection intensity will be analyzed examining population and site and their interaction. These analyses will determine if there is population-specific adaptation to low salinity based on the conditions in which the parent stock of populations came from. Identifying populations of C. virginica that are tolerant of low salinity would facilitate the strategic placement of oyster seed in areas to be impacted by lower salinity to promote restoration, aquaculture, and industry along coastal Louisiana.
