Characterizing the effects of a small waste water treatment plant (WWTP) on a Canadian Great Lake freshwater food web using 13C and 15N

We hypothesize that the Owen Sound WWTP has a detectable effect on the structure and function of the aquatic ecosystem. We predict that by using SIA we will be able to determine the incorporation of isotopically distinct nutrients into lower trophic levels. We also used a mass balance approach in order to quantify the contribution of nutrients into the basin by the major sources of nutrients (WWTP, Sydenham , and Pottawatomi River). There was no significant difference between sample sites using primary consumers, however benthic invertebrates differed significantly between sites and were determined to be equally represented in the diets of lake trout and lake white fish using the IsoWeb. The Owen Sound WWTP effluent contributed \textless 1% of the total N and P entering the Owen Sound basin, and as such represents a minor source of anthropogenic nutrient loading compared to the two rivers discharging into the basin.