ENERGY-METABOLISM DURING DEVELOPMENT OF EGGS AND LARVAE OF GILTHEAD SEA BREAM (SPARUS-AURATA)

Developing eggs and larvae of laboratory-reared gilthead sea bream (Sp arus aurata) maintained in filtered seawater (40 ppt) at 18 degrees C were measured for oxygen uptake, ammonia excretion, contents of free a mino acids (FAA), protein, fatty acids (FA) accumulated ammonia and vo lumes of yolk-sac and oil globule. Absorption of the yolk coincided wi th the consumption of FAA and was complete ca. 100 h post-fertilisatio n. Amino acids from protein were mobilised for energy in the last part of the yolk-sac stage. Absorption of the oil globule occurred primari ly after hatching following yolk absorption, and correlated with catab olism of the FA neutral lipids. Overall, FAA appear to be a significan t energy substrate during the egg stage (60 to 70%) while FA from neut ral lipids derived from the oil globule are the main metabolic fuel af ter hatching (80 to 90%).