Crepidula fornicata L. (gastéropode) dans le bassin de Marennes-Oléron : structure, dynamique et production d'une population

The reproduction of Crepidula fornicata occurs from the end of February to October. This reproduction determines two periods of juvenile settlement, the first early in June and the second early in October. Because of the lack of distinct cohorts, estimation of production and population dynamics was made according to the location of individuals in the chain. This was confirmed by the agreement between the growth rings of the shells and individual location in the chain. The main chain accounted for 80 per cent of individuals, the others being isolated or in collateral chains. The curvilinear growth of Crepidula fornicata in the bay of Marennes-Oléron follows the equation Le = 81.01 (1-e (-0.400 8(t-0,01)). The average yearly production from a population of dry flesh biomass 583 g/m2 is approximately 275 g/m2, and the P/B ratio is equal to 0.46.