In this multi-investigator collaborative proposal the PIs propose an ambitious project that will utilize the diverse strengths of the participants in a multi-faceted investigation of an aquatic food web. Specifically, they will study how gizzard shad influence the trophic structure and community organization in reservoirs and tie this to watershed processes. They examine the central question of whether or not the influence of shad on different groups of organisms is dependent upon lake productivity. Gizzard shade is an omnivorous fish that dominates warm-water lake and reservoir food webs and becomes more important as productivity increases. This research will quantify the watershed features that lead to gizzard shade dominance and investigate how impacts of gizzard shade vary across the productivity gradient. The study will test hypotheses related to the factors causing gizzard shade dominance in hypereutrophic systems and how gizzard shade impacts vary with productivity. Specifically, this research will examine the relationships between nutrient loading, productivity and gizzard shade abundance and effects in 12 Ohio reservoirs, ranging from mesotrophic to hypereutrophic. These comparative field studies will be coupled with a modeling effort aimed at relating these patterns to a broadly applicable theory of aquatic food webs and ecosystem processes.
