Examining the Ecological Physiology of Oysters on a Reef Habitat: Interactions of Dissolved Oxygen
and Disease Dynamics
The parasite
Perkinsus marinus has been present in Chesapeake Bay for almost 50 years. Yet its greatest and most devastating impacts on oysters have only been realized since the mid-1980s, an observation that suggests a combination of environmental factors emerging over the past 20 years may be acting to accelerate the spread of the disease. Prominent among these factors may be the increasing severity of low (hypoxic) or zero (anoxic) oxygen conditions that occur in the Bay. In this study Ken Paynter will try to determine if there is a link between oxygen stress and increased susceptibility to Dermo, the disease caused by
P. marinus. Recent evidence suggests that this may indeed be the case: in a recent study in North Carolina, for example, oysters near the base of mound-type reefs, in hypoxic and anoxic water, were far more likely to become infected by P. marinus than those found near the oxygenated upper reaches of the mound.
Paynter will study the relationship between oxygen levels and Dermo infection by monitoring oyster spat seeded onto a series of newly constructed mounds. Measurements of key biochemical characteristics of the oysters (including internal pH, amino acid and organic acid composition) in relation to the distribution of the disease and changes in oxygen at different positions in the mounds will provide essential clues to the factors that promote or slow the progression of Dermo. The data from this study will have direct application to the design of reefs for the Bay and to ongoing efforts to restore oyster habitats.
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Kennedy T. Paynter
University of Maryland, College Park
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