This study investigates the role of changing environmental conditions over the past century in establishment of Dermo disease (causative agent Perkinsus marinus) in Eastern oyster (Crassostrea virginica) populations in Chesapeake Bay. Simulated distributions of temperature, salinity, and food (chlorophyll, total particulate organic carbon) obtained from a coupled circulation-biogeochemistry model implemented for Chesapeake Bay were used as input to a coupled oyster population-Dermo disease model. The simulated environmental conditions were obtained from 1900 to 1914 and 1980 to 2014 using nutrient and freshwater inputs derived from the Dynamic Land Ecosystem Model configured for the two periods. Environmental conditions for the early 1900s are overall cooler (∼1.5°C) with reduced nutrient loads relative to 1980-2014 conditions. The early 1900s environmental conditions support expected oyster growth with negligible Dermo disease intensity. The increased nutrient loads associated with the 1980-2014 conditions result in increased detritus, which affects the quality of the food supply available to oysters. While oysters grow, the overall warmer temperatures, increased winter temperature minimum, and modified food supply support increased Dermo disease intensity that reaches epizootic levels. The simulations suggest that warming of Chesapeake Bay waters and increased nutrient loads over the past century may have produced conditions favorable to the Dermo pathogen, allowing it to become epizootic in Chesapeake Bay oysters. Implementation of sustainable management consistent with the higher mortality rates generated by Dermo disease is essential to maintain the resource and its attendant ecosystem services.

Eileen Hofmann's research interests are in the areas of physical-biological interactions in marine ecosystems, environmental control and transmission of marine diseases, descriptive physical oceanography, and mathematical modeling of marine ecosystems. She has worked in a variety of marine environments, most recently the continental shelf of the Ross Sea, Chesapeake Bay, and the Middle Atlantic Bight off the east coast of the United States. She has published extensively in marine ecosystem modeling and other areas of marine research. Her contributions to modeling physical-biological interactions in marine systems were recognized by her election as Fellow of the American Geophysical Union.

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