Physiological Studies on Cancer irroratus Larvae. III. Effects of Temperature and Salinity on the Partitioning of Energy Resources During Development

Abstract

Balanced energy budgets were estimated for larval stages of the rock crab Cancer irroratus cultured in 6 combinations of temperature and salinity. The energy consumed by larvae during development increased in all culture conditions although consumption in 10 °C - 30% S was significantly lower than for larvae in other conditions (15 °C - 25 % S, 15 °C - 30 % S, 15 °C - 35 %, 24 °C - 30% S). Maintenance costs for the entire developmental period were highest for larvae cultured at 10°C - 30% S and 15°C - 25% S. Larvae under these conditions had net growth efficiencies of only 32-34 %. In the other temperature and salinity conditions tested, the amount of energy expended for maintenance was generally equal to the amount of energy converted to new tissue with net growth efficiencies varying between 48 and 51 %. These data suggest that the larva's ability to acquire energy resources and effectively partition the energy obtained between maintenance and growth depends on environmental factors. Under certain conditions (lO°C - 30% S, 15°C - 25 %S) larvae are unable to compensate physiologically for environmental changes. One consequence of incomplete physiological compensation is a reduced potential for growth and an overall reduction in the organism's ecological fitness within the zooplankton community.