This study was designed to measure responses of four-year-old black-lip pearl oysters
(Pinctada margaritifera) to different temperatures and food
concentrations and to identify the energy requirements of each sex. Oysters were fed a
monospecific microalgal diet of Isochrysis affinis galbana
(T-iso). Measurements of oxygen consumption and ingestion rates were carried out
at 24 °C and 27 °C and at two algal (T-iso) concentrations: 5000 and 30 000 cell
ml-1. Glycogen content in adductor muscle, absorption efficiency and scope
for growth were also estimated. Females and males responded differently to environmental
factors, with food level being the most influential parameter. Oxygen consumption and
absorption efficiency were significantly higher in females than in males, but males had
significantly higher glycogen content than females. At high food concentration, glycogen
content, ingestion rate, oxygen consumption, and scope for growth were significantly
higher than at the low food concentration. Only absorption efficiency was significantly
higher at the low food concentration. Oxygen consumption was significantly higher at 27 °C
than at 24 °C. These results indicate that females and males have different bioenergetic
functioning and that energy demands for reproduction are higher in females.