Lake Trout as an Apex Predator in Lakes Ontario and Huron

Ecosystem change can affect the structure of aquatic communities thereby altering the magnitude and/or directional flow of energy and critical nutrients through food webs. Apex predators track and integrate these changes in resource availability and ecosystem structure over time. As an apex predator native to Lakes Ontario and Huron, Lake Trout (Salvelinus namaycush) influence the distribution of some prey fish species and also mediate the cycling of energy and nutrients between offshore benthic and pelagic zones. Over the last century however, multiple factors have influenced prey fish distributions within these lakes, decoupling deepwater and pelagic food webs. While Lake Trout are considered habitat generalists, recent evidence in the form of stable isotope (δ¹³C and δ¹⁵N), fatty acids and other chemical tracers, indicates a narrowing diet breadth. Subsequent changes in Lake Trout energetics, reproduction and population stability provide further evidence that Lake Trout’s role as an apex predator may be becoming compromised through modern day top-down and bottom-up effects. Thus, as emerging stresses such as climate warming and continued invasions of exotic species continue to affect these lentic systems, the shifting role of the Lake Trout as an apex predator, and changes in food web structure may force this keystone species towards an ecological tipping point.