Environmental Effects on Perkinsus marinus
Infection Rates, Growth and Survival among Dermo-Disease-Free Juvenile Oysters Planted at Three Salinity Regimes in an Enzootic Chesapeake Bay Oyster Recovery Area
In 1993, representatives of stakeholder interests in oyster restoration in Maryland adopted the Oyster Recovery Action Plan, a strategy designed to more effectively manage around persistent disease and to limit its spread. The key feature of the plan was to establish oyster recovery areas in major tributaries on the western and eastern shores. Agreement was reached that in upriver, low salinity zones, only certifiable disease-free seed could be planted – in effect, this meant only hatchery-reared oysters. Planting of disease-free seed is no guarantee, however, against their susceptibility to acquiring the disease, especially under environmental conditions such as higher salinity that are more conducive to Dermo. A major concern is how disease-free oysters respond to seasonally varying salinity regimes that result from annual variations in precipitation. To address this issue, George Abbe will plant disease-free spat at three sites in the Patuxent River, sites at which salinity and temperatures range widely over a yearly cycle. From differences in response to disease, it should be possible to determine the probability that an oyster of a given size or age will develop Dermo infection, and how this probability will be affected by environmental conditions (temperature and salinity). In addition, the study will shed light on how the prevalence and intensity of Dermo disease in adjacent oyster populations impact newly planted seed. Knowledge gained from this study should help aquaculturists and those engaged in ongoing oyster restoration efforts predict the outcome of oyster plantings under different environmental conditions.
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George R. Abbe
Academy of Natural Sciences Estuarine Research Center
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