Characterizing the effect of a spatial temperature gradient on food web structure in the Bay of Quinte-Lake Ontario ecosystem

In light of environmental changes, management of freshwater fish species not only depends on characterizing who is there, but also quantifying how species are interacting with one another to promote structure and viability within populations. Environmental factors, including that of temperature can alter the usable niche space and govern ecological processes at the community and individual level. The Bay of Quinte-Lake Ontario provides an ideal system to test the effect of a distinct spatial temperature gradient on measures of food web structure, dietary niche width, and feeding preferences of fish species. Species consuming a similar prey base are expected to have enriched δ¹³C and higher δ¹⁵N corresponding to increased physiological demand in warmer environments, similar species will occupy similar trophic positions, there will be greater variability in δ¹³C and δ¹⁵N corresponding to increased omnivory in warm environments, and a greater tendency towards benthic and littoral feeding in shallow warmer environments. Contrary to our expectations, yellow perch (Perca flavescens), was found to be significantly more enriched in δ¹³C in the cooler site of The Bay and occupy a higher trophic position. Interpretation of these results will rely on incorporating stomach-content analysis, stable isotopes of carbon and nitrogen, and traditional health metrics.