The Effects of Seawater Temperature on the Performance of the Tropical Sea Urchin Lytechinus variegatus (Lamarck, 1816)

Abstract

As seawater temperatures rise in the ocean due to global temperature change, altered mean precipitation, and weather patterns, native species face uncertain futures. The alteration in thermal tolerance was assessed in wild-captured tropical sea urchins (Lytechinus variegatus) from the Caribbean Sea and then maintained under controlled conditions. Three experiments were performed: (1) favorable growth temperature: after maintaining wild sea urchins at three different seawater temperatures (22, 24 and 26°C) for 70 days, it was observed that 22°C was the best temperature for growth performance. Sea urchins showed daytime behavior (higher activity at 9:00−10:00 h), during this time period; (2) thermal preference (TP): determined with the help of a horizontal camera with a thermal gradient (19–30°C), it showed that the acclimation temperature influenced the TP of sea urchins, since a significantly higher number of animals opted for the temperature at which they had been acclimated; and (3) critical thermal maximum (CTmax) and critical thermal minimum (CTmin): sea urchins exposed to a progressive temperature change, starting from the acclimation temperature, tolerated the increase in temperature (up to 14°C) better than the decrease (up to 12°C). These results thus contribute to our knowledge of sea urchin thermal biology and provide information about the assessment of thermal comfort conditions in sea urchin farming.