Seasonal variability in diversity and abundance of the free-living pelagic copepod community of the Algerian coasts (SW Mediterranean Sea)

Abstract

Abstract Investigations on the free-living, pelagic copepod community of the Algerian coasts were performed at the Habibas Islands and in Bou Ismail Bay (Sidi Fredj coast) between 0 and 100 meter depth during various seasons of the year 2012-2013. Seventy-seven taxa at species level have been identified, belonging to 47 genera and 24 families. The distribution of the copepod community revealed seasonal variability; high abundance and species richness (greater than 20 species) characterized winter and spring, while the summer period was characterized by low abundance and species richness. The spatial distribution showed high abundance and species richness on the Sidi Fredj coast (the respective mean abundances along the Sidi Fredj coast and at the Habibas Islands were 253.71 ind.m−3 and 109.77 ind.m−3, respectively). Analysis of the samples showed the presence of seven abundant and frequent species: Centropages typicus, Eucalanus elongatus, Pleuromamma abdominalis, Paracalanus parvus, Paracalanus nanus, Calanus helgolandicus, and Temora stylifera. Multivariate analysis (ascending hierarchical classification and non-metric multidimensional scaling) enabled us to group the stations according to the composition in the copepod species, and the influence of seasonal changes was well observed. A dominance of herbivorous behaviour, followed by an omnivorous feeding strategy, was observed in the two studied areas. A dominance of epipelagic and epi-mesopelagic species was observed during all seasons, reflecting a neritic character of both study areas.