Effect of salinity on the temperature preference and tolerance of age-0 mayan cichlids

We measured the salinity tolerance, temperature tolerance, and preferred temperature of the Mayan cichlid Cichlasoma urophthalmus to determine if temperature and salinity would limit the range expansion of this introduced species in Florida. Salinity tolerance at 25°C exceeded 37‰. The upper and lower ultimate lethal temperatures in freshwater were 39 and 15°C, respectively. Acclimation to 15‰ salinity had no effect on the lower incipient lethal temperature (15°C). Thermal preference determined in a horizontal temperature gradient was 32.8°C in freshwater, 39.2°C at 15‰, and 26.9°C at 30‰ salinity. Our results indicated that temperature and salinity are not likely to limit range expansion of the Mayan cichlid from its present location in the southern portion of the Everglades National Park, but that the species’ spread may be blocked by cold winter temperatures in north Florida.