Thermal ecology of red lionfish Pterois volitans from southeast Sulawesi, Indonesia, with comparisons to other Scorpaenidae.
Scorpionfishes (family Scorpaenidae) occupy a wide range of thermal environments, yet little is known about the group's thermal ecology. Recent invasions by red lionfish Pterois volitans and devil firefish P. miles into the Atlantic Ocean and Mediterranean Sea have stimulated interest in the ability of these species to withstand thermal extremes, but current temperature data are limited to cold tolerance estimates, or employ nonstandard techniques, making it difficult to compare values across studies. Using standardized methodologies, we quantified metabolic, physiological, and behavioral thermal responses of red lionfish from the Banda Sea, Sulawesi, Indonesia, and interpret the data in light of the group's diversity and range of thermal habitats. Red lionfish acclimated at temperatures between 13 and 32°C exhibit a thermal scope of nearly 25°C. The resulting thermal niche is moderately large, allowing lionfish to exploit a wide range of thermal habitats, from mid-Atlantic coastal waters to hyperthermal tropical mangroves and tidepools. Although lionfish prefer temperatures of ∼23°C, they acclimate to the high temperature of a cycling thermoperiod. This feature, along with their comparatively low temperature sensitivity (metabolic temperature quotient <2), likely permits lionfish to limit energetic costs during forays into warmer waters. Although lionfishes are considered to be a tropical group, they exhibit a number of thermal tolerance characteristics that allow them to persist in some surprisingly cool environments. Modeling thermal strategies used by red lionfish may provide new insights to the range and variability of thermal adaptations of scorpaenid fishes in general.