The resistance of Crassostrea rhizophorae to starvation and asphyxia

Abstract

Experiments were performed on the oyster Crassostrea rhizophorae in order to determine the degree of its resistance to conditions of starvation and asphyxia imposed by longlasting transportation. The most favorable results were obtained by lowering the environmental temperature to about 15°C, and keeping the oysters in air, with a daily bath in hypercalcic seawater (Ca content double that of seawater). In this way mortality decreases and energetic reserves are not impaired. Oysters kept in water at their normal environmental temperature, without nutrition, reveal a noticeable increase in mortality and a decrease of about 40% in the glycogen and lipid reserves, during a 15 day starvation period. The normal values of some metabolic and compositional indexes in this species are: oxygen consumption 104±6 cm³ O₂/kg living body weight/h; water content 81±1%; protein content 7.4±0.4%; lipid content 1.6±0.1%; glycogen content 6.0±0.5%. The glycogen is distributed almost uniformly throughout all visceral organs. The oxygen consumption shows no circadial or tidal rhythmicity.