Meeting Abstract
Climate change is threatening global biodiversity. An organisms’ sensitivity to climate change depends on their thermal safety margins (i.e., how close they live to their thermal limits) throughout their life histories. Such safety margins are thought to be smaller in tropical terrestrial ectotherms compared to their temperate counterparts due to both local acclimation and adaptation to a relatively stable thermal environment. However, to date, there is little information on the thermal safety margins of marine ectotherms. Importantly, these ectotherms have multi-phasic life histories and depend on a planktonic stage for dispersal. This crucial, but largely unprotected stage is considered to be especially vulnerable to environmental stressors; and is often viewed as the limiting stage for the distribution and abundance of these species. We investigated thermal safety margins of larval and adult stages of two species of mangrove snails, Littoraria ardouiniana and L. melanostoma, Surprisingly, both larvae and adult snails had high and comparable upper thermal limits, lethal temperatures of larvae and Arrhenius Breakpoint Temperature of adults exceeded 43°C. The larval thermal limit was well-above the observed sea surface temperature (Tmax: 33°C), whereas present-day ambient temperatures in the tree canopy could exceed the adult limits (Tmax 46°C). The larval stages, therefore, have a much greater thermal safety margin as compared to the adults, which may reflect adaptation of these marine ectotherms to the most stressful phase of their life cycle.
