PARENT SESSION
Oral Session # 25: Invasive Species II: Aquatic Systems.
Presiding: G Rilov
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 205.
Monitoring fish invasions and their impacts in southern Florida: Can we predict the risks?
Trexler, Joel1, Lorenz, Jerome2, Loftus, William3, 1 Florida International University, Miami, FL2 National Audubon Society, Tavernier, FL3 U.S. Geological Survey, Homestead, FL
ABSTRACT- In a recent paper, we noted that the abundance of non-native fishes was generally low in freshwater marshes of the Everglades at sites distant from canals, but was relatively high in some habitats bordering that ecosystem. Further, we reported a negative correlation over a 10-year period between the numbers and biomass of native fish and the same parameter for the non-native Mayan cichlid, Cichlasoma uropthalmus, in mangrove habitats. Since that publication, we have observed an expansion of Mayan cichlids into Everglades wetlands adjacent to the mangrove zone. These data permit us to estimate a rate of spread of this species. At present, we can identify no statistical evidence for effects from any non-native taxa on native fish communities in freshwater wet-prairie habitats. However, in the mangrove zone on the northern fringe of Florida Bay, the native species sheepshead minnow (Cyprinodon variegatus) and marsh killifish (Fundulus confluentus) decline in abundance in periods when Mayan cichlids are common, and increase following cold weather that decreases cichlid abundance. Two other small, abundant native fishes, sailfin molly (Poecilia latipinna) and rainwater killifish (Lucania parva), appear to be unaffected by the changing abundance of Mayan cichlids. Our work indicates that Mayan cichlids have altered the community structure and dynamics of native fishes in some habitats in southern Florida, but not in others. We use our data to develop a predictive model of the spread of Mayan cichlids into wetlands of the Everglades, as well as their impact on freshwater fish communities there. Further, we discuss the ability to generalize our observations to other expansions and evaluate if predictions can be made early enough to intervene once a new fish species is detected.
Key words: impact assessment, cichlid, invasive species, community ecology