Effects of temperature on fish aggression and the combined impact of temperature and turbidity on thermal tolerance

We compare effects of diel-fluctuating versus stable water temperature regimes on the behaviour and upper thermal tolerance (measured as Critical Thermal Maximum, CTmax) of the Bluntnose Minnow, Pimephales notatus. Fish were acclimated to either a static 18ºC, static 24ºC or a diel-fluctuating treatment of 18-24ºC for a total of 10 weeks. Activity level and aggression were measured for 6 consecutive weeks during the acclimation period. Following acclimation, upper thermal limits of fish from each treatment were measured under two conditions: clear water (< 2 NTU) and turbid water (25 NTU). This was to evaluate effects of acute turbidity exposure that might arise with heavy rain on deforested streams