Factors Influencing Habitat Selection in Fishes with a Review of Marsh Ecosystems

Abstract

We review the general theory regarding habitat selection in fishes and integrate this theory with recent data to evaluate habitat selection by marsh fishes. Models of habitat selection in fishes have evolved rapidly. The earliest models predicted habitat selection based on simple variables like temperature or salinity. Optimal foraging models project habitat selection of individuals based on food availability. Environmental factors and food can be integrated using bioenergetic models to predict the distribution of individuals based on bioenergetic optimization. Habitat selection can be modified by the presence of other individuals including competitors (theory based on ideal free distributions) and predators (theory based on trade-offs of growth vs. predation risk). The most current models use game theory to project the dynamics of habitat selection for both prey species and their mobile predators. In a review of marsh ecosystems, we found that little information is currently available with which to evaluate potential mechanisms underlying patterns of habitat use in these systems. Though marshes are widely considered important for foraging and predator refuge, this function has rarely been measured or critically evaluated. In contrast, measurement has focused on abiotic factors, resulting in a mismatch between factors cited as important and those actually measured. Existing theory on habitat selection in fishes combined with the strong empirical base that has been developed on patterns of habitat use in marsh fishes provides a unique opportunity to begin testing relevant mechanisms underlying distributional patterns. A mechanistic approach is necessary to understand the functional value of habitat to organisms as well as provide a basis for the implementation and evaluation of habitat restoration and management initiatives.