ИСТИНА

The Kerch Strait connects Black and Azov Seas. From 1986 to 2016, 154 species of bottom animals were recorded within its area; they were the following: 1 species of sponges, 4 species of cnidarians, 3 species of nemerteans, 43 species of polychaetes, 1 species of phoronids, 40 species of crustaceans, 1 species of chitons, 15 species of gastropods, 32 species of bivalves, 3 species of echinoderms, and 6 species of ascidians. Oligochaetes have also been found, as wells as bryozoans that were recorded in shell and macrophyte overgrowths. In terms of species richness, crustaceans, polychaetes and bivalve molluscs prevailed. Their share comprised 26, 28, and 20 % of the zoobenthos species richness, respectively. The share of gastropods was around 10 %. Other taxonomic groups amounted only to 16 % of the total species richness of zoobenthos. Polychaetes Melinna palmata and Nephtys hombergii were among constant species, and bay barnacle Amphibalanus improvisus, gastropod Tritia reticulata and bivalves Cerastoderma glaucum, Chamelea gallina, Mytilaster lineatus, Pitar rudis were additional species. The share of constant species was, on average, 12–24 % of the total zoobenthos abundance, but only 1–2 % of its biomass. Additional species comprised 42–77 % of the abundance and 30–40 % of the biomass of zoobenthos. Rare species played relatively small part in the zoobenthos abundance; on average, they comprised 13–30 % of the total abundance. However, they accounted for the major part of the zoobenthos biomass on average, 51–75 %. They also comprised around 95 % of the total species richness of zoobenthos.