1a. Objectives (from AD-416):
Identify and propagate families of commonly cultured eastern US oysters, Crassostrea virginica, that are resistant to key diseases. Families and lines of oysters will be deployed in areas with disease pressure and resistance and susceptibility to four major oyster diseases will be evaluated periodically along with growth parameters. The prevalence of these diseases, and relationship among disease resistance to multiple diseases and to growth will be examined in the families and lines deployed. This information will be used to selectively breed oysters for good industry performance.
1b. Approach (from AD-416):
Families and lines of C. virginica oysters that have been developed at Rutgers University, Virginia Institute of Marine Sciences, and University of Maine, and their crosses will be deployed in regions where outbreaks are expected and predictable. Regular sampling will be conducted to define the disease resistant and disease susceptible phenotypes for two major oyster diseases, juvenile oyster disease (JOD) and an unknown multinucleated sphere haplosporidium (MSX). Further studies will be conducted in Damariscotta and Duxbury to evaluate families of oysters for disease resistance using the defined phenotypes and with regular enough sampling to determine levels of infection and cause of mortality. In addition to monitoring and evaluation for MSX, evaluation for JOD will also be conducted during the early rearing phases in the same populations. Tissue samples will also be collected in order to conduct genotyping and functional genomic assays on the animals with various growth resistance and susceptibility phenotypes.
3. Progress Report:
The goal of this collaborative project is to evaluate the performance of different lines of Eastern oysters, Crassostrea virginica, at different locations throughout the mid-north Atlantic coast of the US, in order to determine the influence of environment on performance. The East Coast Shellfish Breeding Consortium identified 6 lines of oysters with resistance to oyster disease and good growth performance. Broodstock from each of the lines were conditioned and spawned and deployed for performance evaluation in sites with moderate to high disease pressure in Maine (1), Rhode Island (2), New Jersey (1), and Virginia (1). Results indicate that oyster performance for the first year of deployment appears to be driven by mortality, which was highly variable between sites and lines. Unusual levels of mortality during have been detected at the Maine, Rhode Island, and New Jersey sites, and cause for these mortalities is being investigated using a high throughput molecular diagnosis tool developed in this research. Preliminary data indicate the presence of SSO (seaside organism) in Maine, a disease that had not been previously reported in this State. Cumulative percent mortality was highest for the Clinton (CT) line in Maine (80%) and lowest for all lines in the New Jersey site (5 – 18%).