Early stages of marine fish larvae are characterized by fast growth while having a limited aerobic scope and an immature digestive system. In order to understand this apparent paradox, the study of energy allocation is a major necessity. Components of the energy budget of turbot (Scophthalmus maximus) larvae were determined during initial development (days 4–12) and the complete energy allocation budget is presented. It was observed that food absorption efficiency increased from 32 to 51% during the studied period, and so did the energy available for growth and metabolic purposes. The relative amount of energy for maintenance decreased from 71 to 36% of energy channelled to metabolism. Gross growth efficiency increased from 20 to 26% of ingested energy, and net growth efficiency decreased from 66 to 52% of assimilated energy. Reduction of net growth efficiency is the reflex of a higher metabolic rate in older larvae, due to increased costs of activity and growth. Evidence, indicating that metabolic scope of early turbot larva is unable to accommodate simultaneously high levels of growth and activity was found. Alternative strategies to accommodate the costs of growth and activity exist in turbot larvae, and may result in a trade-off between fast growth and viability. As larvae grow, the various physiological processes described get more efficient, and the metabolic scope increases.

This study was financially supported by the Comisio´n Interministerial de Ciencia y Tecnologı´a (CICYT, Spain) under Project AGF 185/92. Isabel Cunha was supported by a doctoral fellowship from FCT–Program Praxis XXI–BD/ 3489/94.

9 páginas, 4 tablas, 2 figuras

Peer reviewed