Thermal Preferences and Critical Temperatures of Invasive Lionfish Complex (Pterois volitans/P. miles)

<p> Temperature preference and limits were determined for locally captured, juvenile lionfish at four different acclimation temperatures (13&deg;C, 20&deg;C, 25&deg;C and 32&deg;C). Temperature preferences were evaluated using an automated shuttlebox system that presents temperature stimuli in a subject-driven fashion. The shuttlebox system circulates two temperatures of water within a dumbbell-shaped tank, maintaining a difference of 3&deg;C between sides. Movement of the subject to the &horbar;warm&Vert; side increased temperature stimulus; movements to the &horbar;cold&Vert; side decreased temperature stimuli in both tanks (maintaining 3&deg;C differential). Subjects move between hot and cold sides, behaviorally thermoregulating within preferred temperature ranges. Critical thermal methodology was used to determine the CTmin and CTmax of the lionfish with loss of equilibrium as the endpoint. Temperature was increased or decreased by 0.33&deg;C per minute until the end point was reached. Thermal tolerance polygons will provide a visual representation to the lower and upper thermal avoidance temperatures of the invasive lionfish, delineating the preferred thermal range of the species. A species&lsquo; thermal preference and tolerance are important mechanistic drivers affecting behavior and geographic distribution and thus are relevant to fisheries management. Thermal preference data could assist lionfish population management in pinpointing abundance hotspots, allowing removal efforts to be more efficient. Thermal tolerance describes the range in which lionfish can survive, and how this range changes with acclimation temperature. Due to increasing ocean temperatures, the current range of the invasive lionfish could expand geographically into higher latitudes, similar to expectations for native tropical fishes, with unknown implications for ecosystem processes.</p>