Spatial-temporal dynamics of the zooplankton community structure in coastal waters near Sevastopol in the spring-autumn period

Abstract

The zooplankton of the coastal water area near Sevastopol is fairly well studied. However, there are few comprehensive studies of zooplankton communities in this region involving the characterization of all taxa that form these communities. Moreover, previous studies were mainly based on materials collected in Sevastopol Bay at only one or two stations: at the entrance to the bay and in the innermost part, while the analysis of the spatial variability of zooplankton within the bay was not carried out. The purpose of this work is to characterize the spatial-temporal dynamics of the zooplankton communities of Sevastopol Bay and the adjacent open waters in the spring-autumn period of 2013. The present work was based on zooplankton materials collected in April-November 2013 in the western, central and eastern parts of Sevastopol Bay, as well as at three stations in the adjacent open waters: two miles from the entrance to Sevastopol Bay, near the Uchkuevka village and at the entrance to the Kruglaya Bay. To identify the similarity/dissimilarity of assemblages and characterize the degree of differences between them, nonparametric multivariate scaling (MDS), analysis of similarities (ANOSIM), and the procedure examining contribution of individual taxa to the average Bray–Curtis dissimilarity between groups of samples (SIMPER) were used. When analyzing beta diversity, the Shannon index was used. The present work has revealed that during the study period between different parts of Sevastopol Bay and the adjacent coastal open water area there were spatial and temporal differences in the abundance and taxonomic structure of zooplankton communities. The total average abundance of zooplankton in the bay in all seasons was higher than in the open coastal area. There is a tendency towards higher density values in the middle part of the bay. The maximum degree of dissimilarity was found between the assemblages of the central-eastern part of the bay and the open waters. It is shown that the degree of complexity of zooplankton assemblages increased in the direction from the eastern part of the bay to the open waters during the summer-autumn period. The lowest level of assemblage diversity was registered in spring throughout the entire study area. It was determined that the differences in the taxonomic structure between the communities of the compared water areas in spring are due to three, in summer – nine, in autumn – five dominant taxa.

Keywords: zooplankton, copepods, taxonomic structure, diversity, Sevastopol Bay