Habitat Partitioning in a Freshwater Fish Community

Abstract

The patterns of habitat utilization in the littoral zone fish community of two small southern Michigan lakes were examined. Abundance and habitat use of the fish were quantified by underwatertransect censuses. The sunfishes (Centrarchidae) dominated the communities numerically and by weight, with two species, the bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) accounting for 85% of the community biomass. Spatial (habitat) segregation of species was evident along gradients of depth (distance from shore), vertical height in the water column, and vegetational structure. Several species showed intraspecific differences in the spatial distribution of size-classes. Comparative analyses of habitat use in the two lakes suggest that small size-classes are confined by predation to areas of dense cover and that within these areas competition determines space utilization by different species. The patterns of habitat use are discussed in relation to the food habits and morphology of species in this community. Only one clear case of segregation of two species by food size occurs (bass and bluegill); most other species segregate predominantly by habitat. The rarer centrarchids show strong niche complementarity with the codominant bass and bluegill.