Abundance and structure of copepod communities along the Atlantic coast of southern Morocco

Abstract

Zooplankton composition and the spatial and temporal abundance distribution of copepods were examined on the southern Atlantic coast of Morocco. In 1998, 31 stations during March and 30 stations during July were sampled on the continent shelf between Cape Blanc (21° O’N) and Cape Boujdor (26°30’N). Holoplankton dominated the zooplankton assemblages. Copepods represented 86% of the zooplankton in March and 73% in July. Herbivorous species were the main components of the 78 identified copepod species (60 species in March and 49 in July). Four species were recorded for the first time in this area: Calanus hyperboreus, Scaphocalanus brevicornis, S. medius, and Heterocope saliens. Both zooplankton abundance and diversity were related to changes in ecological parameters resulting from upwelling currents. The uplift of cold water enriched superficial water layers with nutrients and induced strong primary production upon which zooplankton depend. This study discusses the environmental features that influence plankton resources and the relationship of plankton production to the pelagic fisheries off northwest Africa.