Oyster shell disarticulation in three Chesapeake Bay tributaries

We examined the effects of site location, season of deployment, substrate, size class, and salinity and temperature regimen on the time-since-death (TSD) required for the disarticulation of shells of Crassostrea virginica (Gmelin, 1791) at sites located in three Chesapeake Bay tributaries. The mean TSD required for disarticulation was greatest at Chestertown (815.5 days), intermediate at Oxford (718.9 days), and least at Deal Island (630.0 days), which corresponded to progressively increasing mean salinities. The mean TSD for all sites combined was 739.4 days, ranging from 21 to 1,427 days. Within sites, oyster shell size class (i.e., market-sized >76 mm, small <76 mm) had significant intrasite effects on mean TSD at Chestertown and Oxford, although among sites, a significant interaction existed between size class and sites. Overall, shell length had a strong positive correlation with TSD and accounted for 10.0% of the variability in TSD. Mean annual salinity had a strong negative correlation with TSD, accounting for 18.1% of the variability in mean TSD. The season of deployment of oyster shells had a significant effect on the mean TSD at Chestertown and Oxford. although not in a consistent manner from one site to another. However, overall, the cumulative percentage disarticulation was greatest in summer (47.6%) and least in winter (6.3%). Among sites, the substrate on which the trays were deployed (i.e., reef or sediment) did not significantly affect mean TSD.