Oysters provide essential economic and ecosystem services to coastal communities including Long Island Sound (LIS) where natural, self-sustaining populations supply seed for the Connecticut aquaculture industry. Both regionally and nationally, shellfish restoration efforts continue to increase and expand existing natural beds, presenting an opportunity to increase oyster-related ecosystem services. Little is known, however, about how expansion may affect the proliferation and transmission of oyster parasites between restored and cultured populations. To better understand the host-parasite-environment interactions in a rapidly changing environment, we completed monthly disease (Perkinsus marinus (Dermo), Haplosporidium nelsoni (MSX), Haplosporidium costale (SSO)) and reproduction assessments at two unmanaged, self-sustaining natural oyster beds in Connecticut over two years. Continuous water monitoring (temperature, salinity, dissolved oxygen, chlorophyll, and pH), combined with oyster biometrics, provides a quantitative understanding of the seasonal dynamics and will help to identify relevant water quality variables.
Preliminary analysis shows that the presence of Dermo disease follows historic trends. Body condition scores and gonad development were correlated with temperature. Adult mortality rates of 24-34% were observed during summer months when Dermo infection was high, but overall population densities remained stable as a result of high natural recruitment in the late summer and early fall. Water variables deviated from historical trends, with temperatures frequently exceeding 25°C and pH ranging from 7.0 to 7.7. Further disease analysis using qPCR and histology are underway and will improve our understanding of how changing environmental factors (eg., temperature and pH) are affecting oyster population health and disease progression. Using this comprehensive approach, we aim to fill critical information gaps and develop a hazard analysis to guide restoration planning in a way that promotes the success of natural, restored, and cultivated oysters and in turn supports healthy, resilient ecosystems and coastal communities.