ZOOPLANKTON ASSEMBLAGES AND INFLUENCE OF ENVIRONMENTAL PARAMETERS ON THEM IN A MEDITERRANEAN COASTAL AREA

Temporal dynamics of zooplankton communities and assemblages, as well as the influence of environmental factors on them, were studied in Sar onikos Gulf (Aegean Sea, Greece). Different multivariate techniques (h ierarchical clustering, multidimensional scaling and correspondence an alysis) were applied on a 2 year data set of zooplankton species compo sition, 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 sec ond in Saronikos Gulf proper. Within the latter community, five assemb lages were distinguished: (i) the coastal winter assemblage characteri zed 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 char acterized by Penilia avirostis, Evadne tergestina and Temora stylifera ; (v) the thermophilic assemblage influenced by the open sea and chara cterized 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 (eutrophicatian-pollution, temperature, water mass circula tion, hydrology and topography).