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 persona l 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 literat ure to balance the energy entering the lake with energy present and tr ansferring through the different levels of the food web. A mathematica l model is used to logically integrate the data and to produce a balan ced food web. The mathematical model Network developed by Ulanowicz is used for this purpose. This procedure provides generality and stabili ty to the hypothesized energy flow through the Lake Ontario food web e ven if the final result might not coincide completely with reality. Th e results show that the food web of Lake Ontario is organized in five food chain levels and that recycling plays an important role. The anal ysis of the food web in energy terms is important because it allows th e computation of the fish biomass that can be sustained by primary pro duction. However, confident prediction of the fish biomass can not be performed at present given the lack of data on some important energy t ransfer pathways in the food chain.