The effects of repeat acute thermal stress on the critical thermal maximum (CTmax) and physiology of juvenile shortnose sturgeon (Acipenser brevirostrum)

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University of New Brunswick


The shortnose sturgeon (Acipenser brevirostrum) is a species of special concern in Canada, but little is known about their thermal biology. Information on the upper thermal tolerance of shortnose sturgeon becomes valuable for predicting future survival particularly with climate change and improving species management. Using standard critical thermal maximum (CTmax) methodology, the objective is to determine whether previous thermal stress affected the CTmax of juvenile shortnose sturgeon when exposed to a secondary thermal stress event. Prior exposure to thermal stress did not affect CTmax 2 of juvenile shortnose sturgeon, when a 24h recovery period is allotted between tests. Plasma glucose, lactate and osmolarity were all significantly affected by thermal stress, but values returned to control levels within 24hrs. Hematocrit, plasma chloride and protein concentrations were not significantly affected by thermal stress. The data supports the hypothesis that repeated thermal stress does not affect the CTmax of juvenile shortnose sturgeon.