Date of Award


Publication Type


Degree Name



Earth and Environmental Sciences


Aaron Fisk


Paul Blanchfield



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Lake size is an important factor governing seasonal variation in limnological phenomena, origin of nutrient sources, species interactions, cross-habitat linkages, and trophic pathways, all having complex influences on food web structure and function. Lake size effects are most clearly demonstrated across very wide gradients in surface area or volume. This approach incorporates several complicating and collinear elements such as changing fish assemblages and species richness, and therefore, incorporates additional but unaccounted shifts in food web structure and function. A comparison across a finer lake size gradient where fish assemblages and species richness change little or not at all is needed in order to understand the direct influence of lake size. Here, we quantified spring (May) and summer (August) food web metrics (trophic position, littoral carbon use, and resource partitioning) in six fish species across six lakes (volume = 8.7 x106 m3 to 814.5x106 m3) located in Algonquin Provincial Park (Ontario, Canada) using carbon (d13C), nitrogen (d15N), and sulfur stable isotopes (d34S) . Lake volume was the most important factor describing trophic position and littoral carbon use for all species across all six lakes, except cisco (Coregonus artedi) d34S. Relationships between food web metrics and lake size were not as strong as previous studies that looked at a wider range of lake sizes, and trophic position and littoral carbon use exhibited negative and positive relationships with lake size, respectively, contradictory to previous studies. Even though lake size was still the best predictor of feeding in these species, other lake characteristics, including amount of habitat (littoral:limnetic volume ratio) and nutrients (total phosphorus), were also significant; therefore, comparisons of similar sized lakes should use established relationships for a wider range of lake size with caution.