Max Nourry

Feeding and respiratory time activities in the cupped oysters Crassostrea gigas, Crassostrea angulata and their hybrids

Abstract A comparative study of the ecophysiology of the cupped oysters Crassostrea gigas , Crassostrea angulata and their hybrids was carried out in January 2000. Progenies were obtained by crossing parental oysters that had been previously identified using a diagnostic mitochondrial genome marker. Thus, two pure progenies were obtained by crossing within C. angulata parents (AA) or C. gigas parents (GG). Two other progenies were produced by hybrid crossing of C. gigas females with C. angulata males (GA), or C. angulata females with C. gigas males (AG). Individual measurements of the ecophysiology of 35 animals from each progeny were carried out at 19±1 °C. The oysters were fed Skeletonema costatum . The means of clearance and oxygen consumption rates obtained from continuous data recording over 3 h did not reveal differences between the four lines. However, the feeding time activity (FTA) results showed significant differences: for AA, GG, GA and AG animals FTA were 73±10%, 89±6%, 89±7% and 85±8%, respectively. The FTA of the AA progeny was significantly lower than the three other lines. This study shows that FTA is an ecophysiological parameter that can account for observed differences in growth. The ecophysiological measures should now be completed by a study to determine the optimum temperature for each oyster taxon.