Short-Term Thermal Stress Responses in Washington Clam, Saxidomus purpuratus: Survival, Oxygen Consumption, and Hemolymph Biochemistry

We examined the short-term thermal responses of adult Washington clams (Saxidomus purpuratus) using survival, oxygen consumption rate (OCR), and hemolymph measurements. For survival, 30 clams were assigned to each temperature in three replicate tanks. Respirometry used three independent chambers per temperature, with 10 clams in each chamber. Hemolymph was collected from five clams per tank. Survival and OCR were assessed at 10, 15, 20, 25, and 30 °C. Hemolymph was sampled after 96 h at 10–25 °C and after 24 h at 30 °C because mortality occurred rapidly at the highest temperature. Survival exceeded 90% at 10–20 °C, fell to 70% at 25 °C, and reached 0% at 30 °C after 96 h. The LT50 exceeded 96 h at 10–25 °C but was 43.8 h at 30 °C. OCR increased up to 25 °C and then declined at 30 °C. The Q10 value was highest between 20 °C and 25 °C. After 96 h, glucose, AST, ALT, and TCHO varied among treatments, whereas TG and TP did not. SOD protein abundance was highest at 25 °C. Under the present experimental conditions, 25 °C was associated with marked sublethal stress, whereas 30 °C caused severe short-term stress and exceeded the clams’ short-term tolerance.