Thermal tolerance of cyprinids along an urban-rural gradient: Plasticity, repeatability and effects of swimming and temperature shock.

Urbanization changes the thermal profile of streams in much the same way that climate change is predicted to with higher temperatures, more varied flow and rapid temperature pulses with precipitation events. Whether exceptional tolerance to these altered thermal conditions is a pre-requisite for a fish species to inhabit urban streams or if urbanization has changed the thermal physiology of those fish species that persist in urban streams is unknown, but could help predict the outcome of future climate disruption. To test whether residence in urban streams is associated with altered thermal tolerance, we compared thermal tolerance (CT) and phenotypic plasticity of thermal tolerance (ΔCT/Δ acclimation temperature) in five populations of an urban-tolerant cyprinid, the blacknose dace (Rhinichthys atratulus), from multiple watersheds along an urban/rural gradient.