Fish population dynamics in a seasonally varying wetland

Authors

Donald L. DeAngelis, U.S. Geological Survey and Department of Biology, University of MiamiFollow
Joel C. Trexler, Department of Biology, Florida International UniversityFollow
Chris Cosner, Department of Mathematics, University of Miami
Adam Obaza, Department of Biology, Florida International UniversityFollow
Fred Jopp, Department of Biology, University of MiamiFollow

Abstract

Small fishes in seasonally flooded environments such as the Everglades are capable of spreading into newly flooded areas and building up substantial biomass. Passive drift cannot account for the rapidity of observed population expansions. To test the ‘reaction–diffusion’ mechanism for spread of the fish, we estimated their diffusion coefficient and applied a reaction–diffusion model. This mechanism was also too weak to account for the spatial dynamics. Two other hypotheses were tested through modeling. The first—the ‘refuge mechanism’—hypothesizes that small remnant populations of small fishes survive the dry season in small permanent bodies of water (refugia), sites where the water level is otherwise below the surface. The second mechanism, which we call the ‘dynamic ideal free distribution mechanism’ is that consumption by the fish creates a prey density gradient and that fish taxis along this gradient can lead to rapid population expansion in space. We examined the two alternatives and concluded that although refugia may play an important role in recolonization by the fish population during reflooding, only the second, taxis in the direction of the flooding front, seems capable of matching empirical observations. This study has important implications for management of wetlands, as fish biomass is an essential support of higher trophic levels.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

DeAngelis, D.L., J.C. Trexler, C. Cosner, A. Obaza, F. Jopp. 2010. Fish population dynamics in a seasonally varying wetland. Ecological Modelling 221(8): 1131-1137.