Bullfrog (Lithobates catesbeianus) invasion in Uruguay

This is the first report of North American bullfrogs, Lithobates catesbeianus (=Rana catesbeiana), invasion in Uruguay. This Anura was introduced for farming proposes in 1987, but at present most of the farms are closed. At one of these closed farms, located at Rincón de Pando, Canelones, we report the occurrence of a feral population of L. catesbeianus. This invasion point is at an early stage and restricted to one or two ponds. We also report the effects of L. catesbeianus invasion in the community structure. This includes species composition and species size structure. In this system bullfrog tadpoles constitute a very important proportion of the present biomass. Bullfrog tadpoles appear to be displacing native amphibians and having some type of positive interaction with fishes. At the invaded system we found more fish species and larger sizes of the shared fish species. We analyze the involved risks of this invasion, the ecological impact by predation, the competition and habitat modification, and the potential of bullfrog to act as pathogens vector. We also recommend taking measures in order to avoid the expansion of this population. There is also the need of studies to search for new invasion points in Uruguay, especially where bullfrog farms were located.