SPATIOTEMPORAL VARIABILITY IN POPULATION-STRUCTURE OF OWENIA-FUSIFORMIS DELLE-CHIAJE (ANNELIDA, POLYCHAETA) FROM THE BAY OF SEINE (EASTERN ENGLISH-CHANNEL)

The spatial distribution of the densities and the population structure of the tubicolous polychaete Owenia fusiformis from the whole eastern Bay of Seine were studied on a large scale in the winters of 1986-88. Populations were located on muddy sediments from the Abra alba-Pectinaria koreni community. Populations were characterized by spatio-temporal variability. Nevertheless, three patches of abundance persist: in the northern part of the bay along the "Pays de Caux-, seaward of the Seine estuary and along the "Pays d'Auge". Growth differences were observed between stations: growth was higher in the stations located just seaward of the Seine estuary, and along the "Pays de Caux" northern "Le Havre" where the fluxes of suspended matter were maximum. The consequences of spatio-temporal variability of O. fusiformis were analysed in relations to the dynamics of an insular species.