Meeting Abstract
P2.157 Saturday, Jan. 5 Energy utilization by nonfeeding larvae is affected by rearing temperature WHITEHILL, E.A.G.*; MORAN, A.L.; Clemson Univ.; Clemson Univ. whitehi@clemson.edu
Temperature can have a strong effect on many physiological processes. For ectotherms, environmental temperature is positively correlated with both metabolic rate and energetic output and is negatively correlated with developmental rate. Many marine taxa have lecithotrophic larvae that do not feed, and we do not know if temperature will affect energy utilization in these taxa, therefore affecting larval and juvenile quality. To determine how rearing temperature affects the energetics of nonfeeding larvae, we reared larvae of the facultative planktotroph Clypeaster rosaceus through metamorphosis without food at 23, 27, and 30°C. At multiple developmental stages we measured size, oxygen consumption, protein, lipid, and carbohydrate content, and ammonia excretion. Temperature affected both metabolic rate and larval duration, thus affecting the total amount of energy required to develop from egg to juvenile both directly and indirectly. Larvae and juveniles reared at 27°C were larger and contained more protein and lipid than larvae reared at 30°C. Energy expenditure was lowest at 27°C when summed over development. Larvae reared at 23°C took much longer (2x) to reach metamorphosis, and so despite lower (1-3x) metabolic rates, they consumed more egg energy over development and contained less protein and lipid after metamorphosis. Together these data suggest that the effect of temperature on lecithotrophic larval and juvenile quality will depend on the relative temperature-sensitivities of metabolism and developmental rate over the range of temperatures an organism experiences. At the lower end of a species’ temperature range, development of nonfeeding organisms may be extended to the point where net energy expenditure increases and juvenile quality is compromised; however, in the optimum temperature range, juvenile quality may be enhanced.
