Habitat Heterogeneity and Fish Community Structure: FEB Inferences from North Temperate Lakes

Transcription

1 LIMNOLOGY LIBRAR'{ American Fisheries Society Symposium 16: , 1996 Copyright by the American Fisheries Society Habitat Heterogeneity and Fish Community Structure: FEB Inferences from North Temperate Lakes MELISSA J. WEAVER 1 AND JoHN J. MAGNusoN University of Wisconsin-Madison, Center for Limnology 680 North Park Street, Madison, Wisconsin 53706, USA MuRRAY K. CLAYTON University of Wisconsin-Madison, Department of Statistics 1210 Dayton Avenue, Madison, Wisconsin 53706, USA Abstract.-We review a broad range of studies of north temperate lake fish communities that quantify the role of habitat heterogeneity and biotic interactions in determining community structure. In community analysis, distribution patterns of species are identified, and these patterns are related to environmental and biotic factors using multivariate analysis. The community structure (i.e., species composition, abundance, and distribution) represents the response of the community to past and current socioenvironmental factors, both locally and regionally. Fish community structure and stability (i.e., constancy or resilience) have been associated with the presence, abundance, species composition, growth form, and structural heterogeneity of macrophytes in various studies. The mechanisms that maintain or alter community structure (e.g., predation, anoxia, and invasion), and their relative importance, differ among communities and vary with spatial and temporal scale. However, models can be developed to predict the abundance, species richness, or species distribution of fishes within and among lakes or reservoirs. Through comprehensive analysis of fish communities, fisheries biologists can understand better the structure and dynamics of the systems they study and manage. Fish biologists have traditionally viewed fisheries at the population level, considering individual species in individual lakes, rather than at the community level. Aquatic ecosystems are inherently complex, and understanding the processes that determine the distribution and abundance of single fish populations is demanding. Further, because biotic interactions can be important, understanding the processes that structure a community requires understanding those processes that affect population interactions as well. An alternative approach is to examine the fish community as a whole, searching for similarities and differences in species distribution patterns, and relating them to environmental and biotic factors.'this can be accomplished using multivariate community analysis techniques that consider several variables simultaneously and reduce a complex system to a tractable series of variables (Gauch 1982; Digby and Kempton 1987; Krzanowski 1988). Fish distribute themselves within and among lakes or reservoirs according to their behavioral and physiological requirements and the availability of preferred habitat (Werner 1986). For a single species, the population is most dense where environ- 1 Present address: The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. 335 mental conditions are optimal for that species. However, because habitats are multidimensional, all aspects of the habitat are unlikely to be optimal in the same area. Social factors may lead to displacement of fishes from their preferred habitat (Magnuson et al. 1979). Intraspecific and interspecific interactions (e.g., density dependence, competition, and predation) can alter distributions. One species may displace a competitor to a suboptimal habitat, resulting in reduced growth or survival; however, preferential predation on the stronger competitor may facilitate coexistence (Werner 1986). Thus, it is reasonable to consider the distribution of fishes as a community response to the environment rather than as separate species responses to abiotic and biotic factors. The structure of a community (e.g., species composition, abundance, and distribution) can be viewed as the response of the community to past and current socioenvironmental factors. Fishes with similar responses tend to co-occur, forming distinct assemblages. Thus, classification of assemblages may indicate similarities (within assemblages) and differences (among assemblages) in abiotic conditions as perceived by fishes, or in the strength and direction of biotic interactions (Tonn and Magnuson 1982; Rahel1984). Geophysical barriers or historical events (e.g., glaciation) may also restrict or alter the distribution of fishes and enable the estab-

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