Thermal tolerance and potential distribution of invasive lionfish (Pterois volitans/miles complex) on the east coast of the United States

The occurrence of lionfish (Pterois volitans/miles) complex on the southeast United States shelf represents one of the first documented invasions of a Pacific marine fish species into the western Atlantic Ocean. Temperature has been proposed as a possible factor limiting the range of this introduction. To examine this hypothesis, temperature-tolerance studies were conducted following the chronic lethal minimum protocol, with death as the endpoint. Overall, the mean chronic lethal minimum was 10.0degreesC and mean temperature at feeding cessation was 16.1degreesC. Rate of temperature decrease and acclimation temperature did not have a significant effect on chronic lethal minimum or temperature at feeding cessation. When combined with mean February water temperatures, lionfish thermal tolerance data indicated that lionfish could overwinter on the southeast United States continental shelf, with a northern limit of Cape Hatteras and an inshore limit coincident with the mean 12degreesC isotherm, which equates to a 10degreesC minimum water temperature. The mean 12degreesC bottom isotherm also runs along the continental shelf break (200 m isobath), marking the offshore limit for lionfish on the southeast United States continental shelf. The current southern limit of the invasion is not bound by temperature, as lionfish could survive (but have not yet been reported) on the Florida coast south of Miami, throughout the Gulf of Mexico and Caribbean Sea, extending into the southern hemisphere. Possible reasons for the constrained southern limit may include planktonic transport mechanisms, patterns of juvenile and adult movements, and the initial lionfish introduction site.