Although size and stage-structured populations are ubiquitous in natural communities few studies have examined their ecological consequences. Bluegill, the most common fish species in many small lakes throughout North America, have populations that are functionally stage-structured, with juveniles feeding on soft-bodied littoral invertebrates and adults feeding on limnetic zooplankton. The proposed research will test the hypothesis that bluegill populations link dynamics of littoral and limnetic habitats via their stage-structured habitat use and thus provide a central focus about which the rest of the fish community is organized. The research will examine processes responsible for among-lake variation in the production of large Daphnia, the primary resource of adult bluegill and the factor that explains among-lake variation in bluegill density and growth. Competition between juvenile bluegill and a suite of littoral fish species, including largemouth bass, will be examined using a combination of comparative lake surveys and experimental tests. The research will provide general understanding of the mechanisms and consequences of stage-structured interactions, and can help guide the development of specific management strategies for warm-water fisheries.
