Some observations on the biology and the ecology of a Venus striatula population in the Bay of Douarnenez, Brittany
Résumé
An investigation was made on a subtidal population of Venus striatula (da Costa) in the Bay of Douarnenez Brittany. The main parameters of the biological cycle were evaluated, V. striatula showed a reproductive activity through the year, the spawning phases occurring in spring and autumn. They were correlated with two periods of recruitment in summer and in late fall. Five plurimodal year classes were recognized from the length
frequency histograms. Growth rate was high during the first two years, with an obvious lessening in winter. Sexual maturity was reached when the individuals were 15 mm long. The analysis of the annual rings indicated a maximal longevity of ten years, the maximal observed length being 35 mm. The growth curve was adjusted to the von Bertalanffy equation and comparison was made with other published data from the full species
geographical range. Spatial distribution in Douarnenez Bay was found to be linked to the bathymetric gradient, and influenced by intra- and inter-specific relationships.