Meeting Abstract
Global climate change, in particular warming, is a major threat to marine biodiversity in the 21st century. Tropical species are believed to be especially vulnerable for they are living close to their upper thermal limits and thus have small thermal safety windows. Here, using the sea urchin Lytechinus variagatus, we explored phenotypic plasticity in a tropical species in the face of warming. Specifically, we tested the hypothesis that acclimation to warmer temperatures increase performance at elevated temperature, i.e., acclimation increases the pejus temperature. Larval urchins were reared at three temperatures (26, 29, and 32 ° C), ranging from present day summer temperature to that predicted for Bocas del Toro at the end of this century. We used oxygen consumption and swimming speed as metrics of performance and compared larval performance at 4 different temperatures (the three rearing temperature and 35 ° C). Swimming speed and oxygen consumption rate in general increased with increasing temperature for larval urchins regardless of acclimation history. However, at the highest temperature tested, larvae reared at 26 ° C exhibit metabolic depression but not the others. Interestingly, the increase in oxygen consumption rate between the 3 ° C increases was smaller for the warm acclimated individuals. The importance of acclimation in shaping thermal response imply that natural variation in thermal limits may be larger than previously expected. Increased performance at higher temperatures through acclimation highlights plasticity in tropical species and that they might have the potential to adapt to future climate scenario.
