Ichthyofauna as a Regionalization Instrument of the Coastal Lagoons of the Gulf of Mexico

Marine fishes have been used in the determinations and corroborations of biogeographic hypotheses, as in the southwest Gulf of Mexico (GOM), where the warm-temperate and tropical ichthyofaunas of the Carolinian and Caribbean provinces mix. The objective of this study was to determine if the arrangement of the lagoon-estuarine ichthyofauna of the southwest GOM corresponds to a previous biogeographic hypothesis based on coastal marine ichthyofauna. Based on peer-reviewed and specialized literature, an ichthyofauna distribution database of 15 coastal lagoons distributed from southern Texas, USA, to Campeche, Mexico, was constructed and used to determine beta diversity, taxonomic diversity, and the geographical segregation of lagoons. A database of 115 species was obtained, more than expected for the lagoon systems of the southwest GOM. The lagoon ichthyofauna of the southwest of the GOM did not follow the traditional biogeographic hypothesis; instead, it was segregated into three sections: northern section within the Carolinian Province, central section with major Caribbean influence, and southern section within the Caribbean Province.