Meeting Abstract

96.5  Sunday, Jan. 6  Using energetics of sea urchin development to examine the temperature-size rule WHITEHILL, E.A.G.*; MORAN, A.L.; Clemson Univ.; Clemson Univ. whitehi@clemson.edu

Temperature is one of the most important environmental parameters that organisms experience. Physiological processes such as metabolism are strongly affected by temperature, and temperature-driven changes in metabolic processes can affect how an organism expends and stores energy. Most ectotherms grow to larger sizes when reared at lower temperatures, an effect known as the temperature-size rule (TSR); the TSR may be driven by differential effects of temperature on energy utilization and acquisition. To investigate this hypothesis, we reared larvae of the sea urchin Lytechinus variegatus through metamorphosis at 23, 27, and 30°C and measured size (body length), energy consumption (algal cells consumed), energy expenditure (respiration, ammonia excretion), and energy accumulation (changes in biochemical content) at multiple developmental stages. We found that larvae and juveniles reared at 23°C were larger and had more protein, lipid, and carbohydrate than larvae reared at higher temperatures. Animals reared at 23°C also had greater food intake and reduced energy expenditure. Together these data suggest that the TSR may be driven by increased food intake and decreased energy expenditure at lower temperatures. Also, juveniles which metamorphosed from larvae reared at 23°C had lower mortality rates; this suggests that increases in sea temperature may negatively affect marine invertebrates by lowering the quality of both larvae and juveniles, which in turn could affect recruitment into adult populations.