According to a new study by the University of Guelph, warmer temperatures are having a ripple effect on food webs in Ontario lakes. Researchers have found warmer average temperatures over the past decade have enforced fish to fodder in deeper waters.
Deep in water they hunt different prey species, causing a climate-induced "rewiring" of food webs, altering the flow of energy and nutrients in the lake. Nursing the movement of generalist species like lake trout may offer an early warning system for impacts of climate change on ecosystems. The behavioral changes we see imply major reorganization of ecosystems.
As species are changing their behavior, they are telling us about what's happening around them in their environment. We can use this information.
The study involved tracking lake trout movements and feeding in hundreds of lakes in northwestern Ontario. Fishes were caught to analyze their tissues to see what they ate. The team also used similar data about fish feeding habits and locations across the province.
Tissue analysis showed that lake trout spend more time in deeper water than near shore, although the researchers were unable to identify specific prey species. Lake trout prefer to catch lake herring. Monitoring behavioral changes in species such as lake trout is important for humans who rely on ecosystems for resources and services from food to water quality.
Climate change effects are complicated and vary within ecosystems to create a patchwork of new conditions. Tracking the movement, feeding habits and condition of generalist species such as lake trout may give resource managers an early warning system for detecting the effects of warming.
According to Bartley, it’s important for managing the entire ecosystem and for looking after populations of lake trout, a popular sport fish for angler.
Image Credit: Cornell CALS
