Zooplankton assemblages and influence of environmental parameters on them in a Mediterranean coastal area

Abstract

Temporal dynamics of zooplankton communities and assemblages, as well as the influence of environmental factors on them, were studied in Saronikos Gulf (Aegean Sea, Greece). Different multivariate techniques (hierarchical clustering, multidimensional scaling and correspondence analysis) were applied on a 2 year data set of zooplankton species composition, based on samples collected at five stations of the study area. A clear discrimination of two communities was revealed, the first one in the semi-enclosed polluted northern part (Elefsis Bay) and the second in Saronikos Gulf proper. Within the latter community, five assemblages were distinguished: (i) the coastal winter assemblage characterized by Ctenocalanus vanus, Oithona similis, Clausocalanus pergens and Fritillaria pellucida; (ii) the psychrophilic assemblage influenced by the open sea and characterized by Oithona plumifera and Clausocalanus jobei; (iii) the spring assemblage characterized by Evadne nordmanni and Centropages typicus; (iv) the coastal thermophilic assemblage characterized by Penilia avirostis, Evadne tergestina and Temora stylifera; (v) the thermophilic assemblage influenced by the open sea and characterized by Clausocalanus furcatus. Both zooplankton and environmental data were treated by multiple correspondence analysis which revealed the importance of some environmental factors on zooplankton community composition (eutrophication-pollution, temperature, water mass circulation, hydrology and topography).