Ontogenetic variation in metabolism, biochemical composition and energy content during the early life stages of Farfantepenaeus paulensis (Crustacea : Decapoda : Penaeidae)

Dry weight (DW), oxygen consumption, ammonia-N excretion, proximate biochem ical composition (total protein, carbohydrate, lipid, water and ash), and e nergy content (estimated from biochemical composition and by wet combustion ) were determined in early developmental stages of cultured Farfantepenaeus paulensis. Pooled samples from embryonic, larval and postlarval stages (at 26 +/- 1 degreesC and 34 +/- 1 parts per thousand,) were used for measurem ents. The study focused on physiological and biochemical processes during t ransitional periods of ontogeny, such as hatching, lecithotrophic and plank -totrophic stages, metamorphosis, and the attainment of a benthic existence in postlarva. DW showed higher increment between protozoea I(PZ I) and mys is I (M I) than in the next mysid and postlarval stages. Individual rates o f oxygen consumption and ammonia-N excretion increased, while weight-specif ic rates presented significant reduction throughout development. Higher wei ght-specific oxygen consumption was registered in nauplius III (N III) and PZ I, following a decrease in subsequent stages. Postlarval stages PL V-VI and PL X-XII exhibited the lowest values among the stages studied. Weight-s pecific excretion was high in N III and protozoeal stages, with maximum val ues in PZ II, while the following stages were marked by lower rates. O:N ra tios indicated higher protein catabolism in the stages between egg and M I and a shift to more lipid utilization close to metamorphosis. Water content was higher in the protozoeal stages and decreased afterwards. Higher perce ntages of protein, lipid and carbohydrate (%DW) were observed in egg and na uplius stages. Protein and lipid decreased from the egg through the nauplia r and protozoeal stages, rising again in mysis stages. Lipid content (%DW) decreased in PL V-VI and PL X-XII. Lipid:protein ratios showed an increase of the importance of lipid between PZ III and M II. Carbohydrates represent ed a minor fraction of body composition, and ash percentages increased from egg to a maximum in PZ II, decreasing in subsequent stages. Energy content determined by wet combustion or calculated by energy equivalents presented the same trend throughout development, varying similarly to protein. Prote in was the main energy contributor to body energy in all stages, while the importance of lipid was higher in egg and early naupliar stages. Trends obs erved in metabolic rates and body composition may be associated to morpholo gical and behavioral changes during the early stages of penaeid development , such as the transition from herbivory to omnivory, and the adoption of a benthic existence. Different ontogenetic energy strategies contribute to su cceed through such diverse type of development.