Physiological energetics of brooding in Chilean oyster Ostrea chilensis

The physiology of brooding and non-brooding individuals of the Chilean oyster Ostrea chilensis Philippi was compared. In this species, reproduction occurs once per year, during spring and early summer. The brooding period lasts approximately 7 to 8 wk, during which time larvae live in the infrabranchial chamber of the brooder. In the experiments described here. brooding resulted in significant decreases in the rates of particle clearance, ingestion, faeces production and excretion, although there was no difference in oxygen uptake between brooding and non-brooding oysters. Brooders partially compensated for reduced food intake by increasing absorption efficiency. The scope for growth was much lower in brooding oysters than in non-brooders, largely as a result of the reduced clearance rate of the brooders. The cost of brooding was 6 to 7 J h(-1). Meat weight decreased during the brooding process. After the larvae were liberated, the clearance rate of the brooder increased, reaching values close to those obtained for non-brooding Chilean oysters.