Meeting Abstract
Temperature is a primary determinant of biogeographic distribution in animals due to its influence on biochemical processes. This study explores the possibility that habitat ranges of adult echinoids are linked to temperature sensitivity of metabolic enzymes during the planktotrophic larval stage. The in vitro thermal performance of the regulatory Krebs cycle enzyme, citrate synthase (CS), was determined in several echinoid larvae with the following thermal habitat ranges: Dendraster excentricus (2-28°C), Strongylocentrotus purpuratus (2-24°C), and Strongylocentrotus fragilis (0-10°C). Temperature sensitivity, ranging from 5-35°C, was assessed through Q10 calculations and Arrhenius breakpoint analysis. Q10 analysis showed that D. excentricus was the most temperature sensitive. S. fragilis exhibited a peak temperature sensitivity at 15-20°C and S. purpuratus was relatively insensitive to temperature except at the coldest extreme. D. excentricus did not exhibit any discrete change in activation energy throughout the temperature range, in concordance with its broad habitat temperature range. S. fragilis and S. purpuratus displayed discrete shifts in activation energy at 15°C and 20°C, respectively, matching their relative differences in habitat temperature ranges. The results of this study help to understand how thermal dependence of early life-history metabolic pathways has ramifications for dispersal potential of planktotrophic larvae of benthic marine organisms. This information is important for understanding biogeographic distributions and population dynamics of marine organisms.
