Spatial and Temporal Patterns of Fish Population Dynamics in the Everglades
Carl R. Ruetz III
Annis Water Resources Institute, Grand Valley State University, Muskegon, MI
Joel C. Trexler
Department of Biological Sciences, Florida International University, Miami, FL
Frank Jordan
Department of Biological Sciences, Loyola University, New Orleans, LA
William F. Loftus
U.S. Geological Survey, Florida Center for Watershed and Restoration Studies,
Everglades National Park Field Station, Homestead, FL
Sue Perry
Natural Resources Center, Everglades National Park, Homestead, FL
We examined population dynamics of five abundant fishes in the Florida
Everglades. Fishes were collected with 1-m2 throw traps at 17 sites five times per
year between 1996 and 2001. Our sites were located throughout three watermanagement units (Water Conservation Area 3A, Shark River Slough, and Taylor
Slough), and sampling events corresponded with important transitional phases of
the wet-dry season (i.e., February, April, July, October, and December). We
found significant patterns in fish density across space and time for all species.
Variation in fish density among sites within water-management units was greater
than among water-management units, and intra-annual variation was greater than
among years for most species. These patterns in fish density were affected by
local hydrology. We found significant relationships between fish density and
time since the most recent drought, although the strength of these relationships
varied among sites. Heterandria formosa, Lucania goodei, Fundulus chrysotus,
and Jordanella floridae were most strongly affected by drought, whereas the
response of Gambusia holbrooki was weak and variable. Densities of
Heterandria formosa, Lucania goodei, and Fundulus chrysotus usually increased
gradually following a drought. In contrast, densities of Jordanella floridae
recovered quickly following a dry-down event and then usually declined. Our
results suggest that local hydrology is an important factor shaping patterns of fish
population dynamics across the Everglades landscape.
Carl R. Ruetz III, Annis Water Resources Institute, Grand Valley State
University, Lake Michigan Center, 740 West Shoreline Drive, Muskegon, MI
49441, Phone: 616-331-3946, Fax: 616-331-3864, Email: ruetzc@gvsu.edu