CHANGES IN CHEMICAL-COMPOSITION AND BIOMASS DURING THE TRANSITION FROM ENDOGENOUS TO EXOGENOUS FEEDING OF SPARUS-AURATA L (PISCES, SPARIDAE) LARVAE REARED IN THE LABORATORY

Larvae of the gilthead seabream, Sparus aurata L., were reared during the first weeks after hatching at 16, 19.5 and 24-degrees-C. Changes in biomass were studied in terms of dry weight and of carbon, nitrogen and hydrogen content. Body composition varied primarily during the period of absorption of yolk and shortly after the onset of exogenous feeding. During the yolksac stage, dry weight and carbon and hydrogen content decreased markedly from their values at hatching, while nitrogen content showed only a very slight decrease. After the absorption of yolk, whether in the presence or absence of food, the percentages of carbon, hydrogen and nitrogen tended to remain constant. No important differences were found in the body composition of growing larvae in relation to temperature. However, the rates of variation of the body constituents were more influenced by temperature in the yolksac stage than during the exogenous feeding phase.