Global warming impacts on lake trout in arctic lakes

Arctic freshwater ecosystems may be sensitive indicators of climatic warming trends because they have relatively few species and simple food webs. Many of these systems are dominated by lake trout, which act as keystone predators. For arctic Alaska Toolik Lake, we have a 16-yr record of physical, chemical, and biological data. Our temperature data show a 3 degrees C increase in mean July epilimnetic temperatures. An individual-based bioenergetics model for young-of-year (YOY) lake trout in the lake was used to examine the effects of climate warming on growth of YOY lake trout. Our simulation models predicted that with a July temperature increase, YOY lake trout would need to consume >8-fold more food (>10-fold with seasonally increased temperatures) to achieve the same end-of-year size as historically surviving YOY lake trout. We have observed no increase in food availability in the lake, and recent analysis shows that primary productivity has actually decreased. If recent changes in the lake foreshadow a long-term trend, our model results suggest that YOY lake trout will not survive their first winter. Such changes, coupled with other current anthropogenic impacts in the arctic, may disrupt lake trout control of the trophic structure in arctic lakes.