Energy flow through the Lake Ontario food web: conceptual model and an attempt at mass balance

The trophic status of Lake Ontario is studied in energy terms, and the information summarized as a food web. Both published data and personal communications are used; critical data deficiencies are pointed out. The underlining assumptions of the model are described along with the research needed to fully test these assumptions. The food web is not balanced in energy terms. Not enough information exists in the literature to balance the energy entering the lake with energy present and transferring through the different levels of the food web. A mathematical model is used to logically integrate the data and to produce a balanced food web. The mathematical model Network developed by Ulanowicz is used for this purpose. This procedure provides generality and stability to the hypothesized energy flow through the Lake Ontario food web even if the final result might not coincide completely with reality. The results show that the food web of Lake Ontario is organized in five food chain levels and that recycling plays an important role. The analysis of the food web in energy terms is important because it allows the computation of the fish biomass that can be sustained by primary production. However, confident prediction of the fish biomass can not be performed at present given the lack of data on some important energy transfer pathways in the food chain.