The Biologists' Forum: A trophic cascade synthesis: review of top-down mechanisms regulating lake ecosystems

This paper evaluates the Trophic Cascade hypothesis and its predictive effects of food web structure regulation on primary productivity in lake ecosytems. The hypothesis prognosticates that the top of the aquatic food web, either with or without piscivorous fishes, should have cascading interactions through the trophic levels ultimately impacting algal biomass. Extensive experiments have shown validity to the hypothesis, while critics of the idea, through their own research, claim that it is too simplistic of a mechanism lost in the complexities of food web dynamics and nutrient loading models. I discuss the development of the Trophic Cascade hypothesis, its strengths and weaknesses, and conclude with the recognized and current synthesis. Many researchers now recognize the interactions of both top-down foraging mechanisms and bottom-up nutrient loading dynamics on lake primary production when assessing lacustrine systems.