Critical thermal maxima of two species of estuarine fish

Critical thermal maxima (CTM) were determined for winter flounder (Pseudopleuronectes americanus, Walbaum) and scup (Stenotomus chrysops, L.), acclimated to ambient water temperature or constant increments above ambient. The acclimation regimes simulated a natural environment by tracking the temperature fluctuations in Point Judith Pond, a small Rhode Island estuary. An elevation in CTM from 30.2° to 35.6°C was observed for scup as the mean acclimation temperature increased from 14.8° to 22.2°C. CTM for flounder increased from 26.4° to 32.4°C over an acclimation range of 4.2° to 23.0°C. The use of CTM studies for predicting the effects of heated effluents is discussed.