Abstract

A literature review of the nonindigenous aquatic species introduced into Florida determined that at least 19 plant, 6 mollusk, 38 insect (including species that were imported as biological control agents), 83 fish, 2 amphibian, 1 reptile, 3 bird, 1 mammal, and 1 crab species and an unknown number of pathogens and parasites have been introduced into Florida. Nineteen species of exotic aquatic plants are established in Florida. Hydrilla (Hydrilla verticilata), water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), and alligator weed (Alternanthera philoxeroides) are the major problem species, requiring significant annual expenditures for control. The Asian Clam (Corbicula) is among the 6 species of freshwater mollusks that were introduced and are established in Florida. There have been 12 migrations or unintentional introductions of aquatic insects into Florida and 27 importations of insects for evaluation as biological control agents of aquatic nuisance species. Of these, 14 species have been released and 4 are still under evaluation. Twenty-three exotic tropical fish species and 1 temperate exotic fish species have become established. The populations of 11 are expanding, and populations of 12 are locally established. The blue tilapia (Tilapia aurea), walking catfish (Clarias batrachus), black acara (Cichlasoma bimaculatum), and blackchin tilapia (Tilopia melanopleura) are the most widely spread exotic fish species. The marine toad (Bufo marinus), and Cuban treefrog (Osteopilus septentrionalis), spectacled caiman (Caiman crocodilus), muscovy duck (Cairina moschata), and the nutria (Myocastor coypus) were released or escaped and became established.

The culture of tropical, exotic plants and animals supports a large aquaculture industry in Florida, which has historically been responsible for the release of many species into the wild. However, the rate of introductions through this pathway has been reduced in recent years. The harmful and beneficial ecological and economic effects of these introductions are not well documented.

The major pathways of unofficial introductions of fishes include escape or release from fish farms, intentional release of species to support established populations for a sport or commercial fishery, and disposal of unwanted pet aquarium fishes. Only two fish species, the peacock cichlid (Cichla ocellaris) and the speckled pavon (Cichla temensis), were studied before being officially released by the Florida Game and Fresh Water Fish Commission. A sport fishery for the peacock cichlid has developed. The introduction of exotic pathogens and parasites by the fish-culture industry in Florida is also poorly documented. There is no evidence that these pathogens have harmed wild, free-ranging, native fish species.

Key words: Nonidigenous, Exotic, Aquatic, Plants, Fish, Animals, Pathogens, Florida.

This report is primarily about the introductions of nonindigenous aquatic species into the state of Florida, about their status, pathways and times of introduction, and about their economic and environmental effects on the native flora and fauna. Our research was limited to a literature review and to updates from experts on some species.

Our report is about one of two biological studies that were funded by the task force under the Nonindigenous Species Prevention and Control Act of 1990. The information on the significant economic and ecological effects of the various species sets priorities for future research and for the development of prevention and control of nuisance species and may serve as a basis for future discussions in a national workshop for the reduction or elimination of new introductions of injurious species.