Oyster Reef Connectivity Inferred Via Population Genetic Analysis

A panel of single nucleotide polymorphism markers (SNPs) was developed for use in genetic analysis of the Eastern Oyster, Crassostrea virginica, sampled from the lower Chesapeake Bay. This project was designed in collaboration with the Chesapeake Bay Foundation (CBF) to test a hydrodynamic connectivity model intended to predict where oyster larvae produced in the Lafayette River, Virginia would settle. To test the model, wild oysters from Tangier Island, VA and the Haskin NEH hatchery strain were planted in the Lafayette River. Baseline samples were taken from the nearby Lafayette, Elizabeth and James Rivers before deployment of the planted test oysters. Newly recruited oyster spat were sampled from the Lafayette River in the summer following deployment of the planted test oysters. The baseline samples and spat were genotyped and assignment tests were performed to identify the source population(s) for the spat. There was a weak pattern of isolation by distance among oysters sampled from the lower Chesapeake Bay, suggesting that the connectivity of the reefs is high. The Haskin NEH oysters were significantly different from the other oysters in the study; however, the Tangier Island oysters could not be discriminated from the oysters sampled in the lower Chesapeake Bay. The genetic data obtained could not provide unequivocal support for the predictions of oyster spat distributions by the connectivity model, although, the data do support the overall circulation patterns in the region predicted by the model. Results indicate that these markers could be useful for discriminating hatchery strains from wild populations.