Biology of the suprabenthic mysid Schistomysis assimilis (Sars, 1877) on Creixell beach, Tarragona

The suprabenthic mysid Schistomysis assimilis (Sars, 1877) was sampled monthly during 1991-1992 in the surf zone of Creixell beach (Tarragona, Spain, northwestern Mediterranean) in order to describe its life history and estimate its secondary production. In the unstable coastal soft-bottom environment studied, this resident mysid is one of the suprabenthic community’s dominant species. Demographic analysis suggests that it is a trivoltine species with a potential longevity of less than one year. According to the size frequency method, its annual production was estimated at 103.55 mg/5 m2, with a P/B ratio of 9.12