Larval settlement and spat recovery rates of the oyster Crassostrea brasiliana (Lamarck, 1819) using different systems to induce metamorphosis

This study aimed at the assessment, in the laboratory, of the larval settlement and spat recovery rates of oysters of the species Crassostrea brasiliana using plastic collectors, epinephrine (C9H13NO3 C4H6O6) and shell powder in settlement tanks. Polypropylene was used attached to bamboo frames. The material was chosen due to its pliability - that favours the spat detachment. Two experiments were carried out; the first between February and April 2008, and the second between November and December 2008 at the Marine Mussel Laboratory of Santa Catarina Federal University (Laboratorio de Moluscos Marinhos da Universidade Federal de Santa Catarina). In the first experiment, the scratched plastic collectors were tested consorting them with shell powder; on the second, the plastic collectors were tested consorted with shell powder, only shell powder and epinephrine as the metamorphosis stimulator. The quantification was carried out of the larvae settled in the plastic collectors, and of the recovery and integrity of the spats after their detachment. The first experiment has shown a recovery rate of 48.83% of the spats in comparison with the D larvae used. From this percentage, 4.9% settled in the plastic collectors and 43.93% in shell powder. The second experiment revealed 55.78% regarding the settled spats in comparison with the total of larvae used (using epinephrine), 78.62% in the treatment with the collector plus shell powder and 58.33% in the treatment only with shell powder. Thus, the use of the collector plus shell powder resulted in a greater spat recovery when compared to the other treatments.