Physiological and Ecological Effects of Increasing Temperature on Fish Production in Lakes of Arctic Alaska

Lakes are sensitive integrators of climate-induced changes and prominent features across the Arctic landscape.  Despite many studies on the implications of climate warming, how fish populations will respond to lake changes is uncertain for Arctic ecosystems.  Least Cisco (Coregonus sardinella) is a bellwether for Arctic lakes as an important consumer and prey resource.  We used a bioenergetics model to simulate changes in Least Cisco production under future climate scenarios for lakes in lowland permafrost regions.  Production of Least Cisco increased under all future scenarios with progressively more growth in warmer temperatures.  Higher variability occurred with longer projections of time mirroring the expanding uncertainty in climate predictions further into the future.  In addition to direct temperature effects on Least Cisco growth, we also considered changes in lake ice phenology and prey resources for Least Cisco.  A shorter period of ice cover resulted in increased production, similar to warming temperatures.  Altering prey quality had a larger effect on fish production in summer than winter and increased relative growth of younger rather than older age classes.  Understanding the implications of increased production of Least Cisco to the entire food web will be necessary to predict ecosystem responses in lakes of the Arctic.