New research from scientists at the University of Guelph sheds light on how climate change is impacting food webs in Canadian lakes. The study was published in the journal Nature Ecology and Evolution and highlighted conclusions from tracking lake trout movement and feeding in hundreds of lakes in northwestern Ontario.
"We can harness the natural capacity of species to detect and respond to changes in their environment," said Tim Bartley, lead author of the study. "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 behavioral changes we see imply major reorganization of ecosystems."
Changing temperatures in lake systems have pushed fish species used to cold water to reside in deeper waters, where they end up hunting different prey species. This ultimately changes the food webs that make up the flow of energy within ecosystems. Lake trout are a good indicator species because they are a generalist species, meaning they are able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources.
To determine the influence that temperature changes have on lake trout, Bartley analyzed fish tissues to find out what the fish were eating. Bartley’s team combined their analysis with data from the Ontario Ministry of Natural Resources on fish feeding habits and locations across the province and found that lake trout spend more time in deeper water than near shore. Bartley hypothesized that this may be because their prey has relocated to colder waters and the trout must follow their prey.
The researchers call this phenomenon “climate-induced re-wiring,” referring to the systemic changes that are seen due to warming temperatures. According to Science Daily, other scenarios of re-wiring have been documented in previous studies, including with grasshoppers and spiders in grasslands, beluga whales and halibut in Nunavut, polar bears and ringed seals across the Arctic, and Kodiak bears feeding on elderberries and sockeye salmon on the Pacific coast.
The scientists urge that monitoring these changes are key, as they could help us better understand and detect the effects of warming. "With further research, we can harness generalists' responses to predict functional outcomes of climate change on the world's ecosystems," the authors write in the study.