Thursday, August 10, 1:30-5:00 pm
COS 103 - Ecology of natural and created wetland ecosystems
Heritage Ballroom I, Marriott
Presiders: G Ervin and S Hoeppner

Seasonal use of alligator ponds by wetland fishes: dealing with drought.

Ruetz, Carl*,1, Trexler, Joel2, Dorn, Nathan3, Chick, John4, Loftus, William5, 1 Grand Valley State University, Muskegon, MI2 Florida International University, Miami, FL3 Florida Atlantic University, Davie, FL4 Illinois Natural History Survey, Brighton, IL5 USGS-Florida Integrated Science Center, Homestead, FL

ABSTRACT- Seasonal water fluctuations are a pervasive feature of many wetlands and can cause high mortality among fishes that become stranded when marsh surfaces dry. We examined the seasonal use of alligator ponds (i.e., deep-water refugia) by large fishes (standard length > 8 cm) in the Florida Everglades. Fishes were collected with an airboat electrofisher at 35 alligator ponds 2-4 times per year between 1998 and 2004. Alligator ponds were located throughout three water-management units, and sampling events corresponded with important transitional phases of the wet-dry season. We encountered 21 fish species during electrofishing surveys with yellow bullhead (Ameiurus natalis), warmouth (Lepomis gulosus), and Florida gar (Lepisosteus platyrhincus) being the dominant species. We found catch per unit effort (CPUE) for total fish differed significantly between water-management units and over time. In general, CPUE peaked during the dry season (April), followed by a precipitous decline that approached the lowest levels during the wet season (July and October). This pattern was apparent during years when there was severe drought (i.e., much of the marsh surfaced dried) and years when water was present over much of the marsh surface in the dry season. Therefore, our findings show that ecosystem engineering by alligators provide habitats that are readily used by wetland fishes as deep-water refugia during the dry season in both wet and dry years.

Key words: freshwater wetlands, fish, disturbance/drought

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