Biologie Du Mysidacé Suprabenthique Schistomysis Parkeri Norman, 1892 Dans La Zone Sud Du Golfe De Gascogne (Plage D'Hendaye)

Abstract

Abstract The suprabenthic mysid Schistomysis parkeri was monthly sampled in 1991-92 in the swash zone of Hendaye beach (southeastern part of the Bay of Biscay) to determine its life history pattern and secondary production. This motile species is one of the main components of the suprabenthic assemblage inhabiting this exposed beach. Characterized by a patchy distribution and a narrow bathymetric zonation parallel to the shore line, its mean density fluctuated between 6 and 443 individuals per 5 m-2 during the sampling period; nevertheless, the population migrates to deeper grounds of the bay when bad weather occurs. It breeds throughout the year with a maximal recruitment in July and produces three successive generations. The potential longevity of individuals is less than one year and differs between generations. Using the size frequency method, its annual production was estimated to 263 mg 5 m-2 with a corresponding P/B ratio of 9.7; calculated by a multiple regression model, the production estimate was 35% higher but the P/B ratio was in the same order of magnitude.