Cilioplankton communities as an indicator of the pollution degree in the Caspian Sea

During 2014-2021 years a study of the species diversity of planktonic ciliates of the Caspian coast of the Absheron Peninsula was conducted. As a result of research in planktonic communities of free-living ciliates, 62 species, belonging to 22 families were observed. Among the recorded families, Strombidiidae takes first place in terms of the number of species. The families Uronychiidae, Nassulidae, Epistylidae, and Zoothamniidae were represented by only one species. A correlation between similarity of the planktonic ciliates species diversity and the degree of organic pollution of coastal area marine water has been established. The results of the cluster analysis showed that the highest similarity of the species diversity (95.5%) was noted for two collection points on the northern coast of Absheron, near the settlements of Novkhani and Bilgah. This is due to the fact that the northern coast is less polluted by oil products and domestic sewage. Thus, according to the similarity of species diversity of planktonic communities of ciliates on the coast of the Absheron Peninsula, the two clusters are clearly distinguished. One unites the cleanest sites (Novkhani and Bilgah - 95.5%), and all the other 4 stationary points of the collection (Sumgait, Turkan, Shikh, Sangachal - more than 50%) are combined into the second cluster.