Comparison of zooplankton communities between cold and hot seasons in Lobito-Angola

Abstract

Composition, distribution and abundance of zooplankton were investigated in hot season and cold seasons at seven stations in Lobito-Angola. Water temperature and salinity was collected simultaneously with zooplankton in hot season (February) and cold season (July) of 2014. Total of 11 phyla were identified. Among them, 54 species of copepods, and 2 species of tunicates occurred, being represented one species in other taxa. Number of species was highest in cold season (49 species) than hot season (43 species). Copepods represented the predominant component both in hot and cold seasons (92.2 and 74.5% of the total community respectively). Zooplankton density was highest in hot season with an average 763.6 inds.m-3 while in cold season was 60.8 inds.m-3. Harpacticoids, Oncaea spp., Calanoides spp., Acartia spp., Calanus spp., copepod nauplius, Corycaeus spp., Oithona spp., and Temora spp. were dominant making up 87.9 % of the total density in hot season. In cold season Oncaea spp., Calanus spp., Calanoides spp., Centropages spp., Metridia spp., Nanocalanus spp., Oithona spp., Pleuromamma spp., Subeucalanus spp. and Temora spp., were dominant making up 68.4 % of the total density. Although not significant with salinity, most of copepods dominant species showed positive correlations with temperature and salinity. However, negative correlation was observed between the density of copepod nauplius and salinity. This study showed that zooplankton communities vary with season and affected by hydrological variables, mainly temperature which seems to regulate the zooplankton abundance.