Indicator benthic microalgae in assessment of the degree of organic water pollution on the example of Crimean coastal waters of the Sea of Azov

Data of the study of microphytobenthos of Crimean coastal waters of the Sea of Azov during 2005–2006, 2008–2011 and 2014 at 17 stations in the Sivash Gulf (East and West), Kamysh-Burunskaya Bay (Kerch) and bays of Kazantip Cape are given. Totally 200 taxa of microalgae belonging to 77 genera were found. Of these, 78 species – saprobity indicators, related to cyanobacteria (17 %) and diatoms (83 %), from 39 genera, for which bioindicative characteristics of organic water pollution are known, are used for the analysis of different ecotopes and regions. A leading place in microalgae flora belongs to a group of betamesosaprobionts (31 species) – indicators of moderate organic pollution, or of the III class of water quality with index of saprobity S = 2.0. The second place belongs to a group of oligosaprobionts (10 species), or of the II class of water quality, which is typical for natural clean waters with S = 1.0. According to the indicator of microalgae, there are no negative changes in the water quality in the regions. This indicates that anthropogenic impacts do not exceed the self-restoring potential of the marine ecosystems. However, the presence of the IV class of water quality indicators (17–21 %) in benthic communities indicates a constant flow of organic substances, which are gradually utilized by the living component of coastal ecosystems. The comparative data of the ratio of the Sea of Azov indicator microalgae species with those of other seas of moderate latitudes are discussed.