Critical thermal maximum and hematology of Atlantic sturgeon (Acipenser oxyrinchus) after repeated exposure to thermal challenge separated by three different recovery times

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University of New Brunswick


To determine the effect of a thermal stress in the form of a critical thermal maximum test (CTmax) on the subsequent critical thermal maximum and hematology of Atlantic sturgeon, fish acclimated to 19 °C were exposed to either no thermal stress (i.e., control; n=6), one CTmax test only (n=6) or two CTmax tests separated by a 1 hour (n=6), 2 hour (n=7) or 24 hour (n=6) recovery period. The critical thermal maximum of the first test (CTmax 1) was not significantly different from that of the second test (CTmax 2) across all recovery periods. Similarly, the hematological values tested (hematocrit, plasma osmolality, and plasma lactate, chloride, glucose, and protein concentrations) did not display strong sensitivity to thermal stress. It is proposed that the high acclimation temperature may mask the effect of CTmax 1 on CTmax 2, or that Atlantic sturgeon are not strongly sensitive to repeated thermal stress.