WETLANDS, Vol. 24, No. 3, September 2004, pp. 652±664 q 2004, The Society of Wetland Scientists SPATIAL SCALE AND ABUNDANCE PATTERNS OF LARGE FISH COMMUNITIES IN FRESHWATER MARSHES OF THE FLORIDA EVERGLADES John H. Chick1, Carl R. Ruetz III2, and Joel C. Trexler Department of Biological Sciences, Florida International University Miami, Florida, USA 33199 1 Present address: Great Rivers Field Station Illinois Natural History Survey 8450 Montclair Ave. Brighton, Illinois, USA 62012 E-mail:
[email protected] 2 Present address: Annis Water Resource Institute Grand Valley State University 740 West Shoreline Drive Muskegon, Michigan, USA 49441 Abstract: Anthropogenic habitat alterations and water-management practices have imposed an arti®cial spatial scale onto the once contiguous freshwater marshes of the Florida Everglades. To gain insight into how these changes may affect biotic communities, we examined whether variation in the abundance and community structure of large ®shes (SL . 8 cm) in Everglades marshes varied more at regional or intra- regional scales, and whether this variation was related to hydroperiod, water depth, ¯oating mat volume, and vegetation density. From October 1997 to October 2002, we used an airboat electro®sher to sample large ®shes at sites within three regions of the Everglades. Each of these regions is subject to unique water- management schedules. Dry-down events (water depth , 10 cm) occurred at several sites during spring in 1999, 2000, 2001, and 2002. The 2001 dry-down event was the most severe and widespread. Abundance of several ®shes decreased signi®cantly through time, and the number of days post-dry-down covaried signif- icantly with abundance for several species.