JOST, J.A.; HELMUTH, B.S.T.; Univerisity of South Carolina, Columbia; University of South Carolina, Columbia: Thermal stress in a Southern salt marsh: Effects of season, habitat, and body size on the body temperature of Geukensia demissa

The Atlantic ribbed mussel, Geukensia demissa exhibits a large habitat range that extends along the Atlantic coast of the United States from New England to Northeast Florida. Past studies have indicated that this species is capable of surviving a wide range of body temperatures, from �20°C to 40°C. While studies have observed the physiological tolerances of this species in relation to temperature, the body temperature patterns in the field are not known, specifically the effects of varying conditions such as season, microhabitat, tidal height, and body size. Therefore, the level of thermal stress experienced by this species is not known. Preliminary lab experiments show that body size and microhabitat conditions (such as exposure level above the substrate, solar radiation, and wind speed) play a large role in the body temperature of these mussels. Estimated body temperature data for four microhabitats and three body sizes collected at the North Inlet Estuary in Winyah Bay, SC show that the body temperature of Geukensia demissais very close and often above its suggested themal maximum in the summer months. While this may be expected in a Southern salt marsh, the data also indicate that this species may be living very close to its lower thermal limit during the winter months, with body temperatures as low as �20°C. Therefore, these data suggest that there is a great deal of variation in the thermal patterns of Geukensia demissa as a result of microhabitat and body size.