Empirical Assessment of Fish Introductions in a Subtropical Wetland: An Evaluation of Contrasting Views |
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Authors: | Joel C Trexler William F Loftus Frank Jordan Jerome J Lorenz John H Chick Robert M Kobza |
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Institution: | (1) U.S. Geological Survey, 7920 NW 71st Street, Gainesville, FL 32653, USA;(2) U.S. Geological Survey, 40001 State Road 9336, Homestead, FL 33034, USA;(3) Present address: Aquatic Research &; Communication, LLC, 1759 NW 20th Street, Homestead, FL 33030, USA;(4) South Florida Water Management District, Everglades Division, 3301 Gun Club Road, West Palm Beach, FL 33406, USA |
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Abstract: | We summarized data from eight quantitative fish surveys conducted in southern Florida to evaluate the distribution and relative abundance of introduced fishes across a variety of habitats. These surveys encompassed marsh and canal habitats throughout most of the Everglades region, including the mangrove fringe of Florida Bay. Two studies provided systematically collected density information over a 20-year period, and documented the first local appearance of four introduced fishes based on their repeated absence in prior surveys. Those species displayed a pattern of rapid population growth followed by decline, then persistence at lower densities. Estuarine areas in the southern Everglades, characterized by natural tidal creeks surrounded by mangrove-dominated marshes, and canals held the largest introduced-fish populations. Introduced fishes were also common, at times exceeding 50% of the fish community, in solution holes that serve as dry-season refuges in short-hydroperiod rockland habitats of the eastern Everglades. Wet prairies and alligator ponds distant from canals generally held few individuals of introduced fishes. These patterns suggest that the introduced fishes in southern Florida at present may not be well-adapted to persist in freshwater marshes of the Everglades, possibly because of an interaction of periodic cold-temperature stress and hydrologic fluctuation. Our analyses indicated low densities of these fishes in central or northern Everglades wet-prairie communities, and, in the absence of experimental data, little evidence of biotic effects in this spatially extensive habitat. There is no guarantee that this condition will be maintained, especially under the cumulative effects of future invasions or environmental change. |
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Keywords: | canals cichlids Everglades exotic fishes Florida introduced fishes invasion non-indigenous fishes wetlands |
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