ICHTHYOFAUNA OF ECOTONE ZONES OF CAPES ECOSYSTEMS OF THE NORTHWESTERN BLACK SEA

Abstract

The present study examines the species composition and some ecological and ecological-morphological features of the ichthyofauna of the ecotone zones of capes ecosystems of the northwestern part of the Black Sea. In the northwestern part of the Black Sea, capes are formed in coastal zones subject to erosion and are natural accumulations of hard substrate surrounded by loose sediments. Transitional landscapes and biotopes are ecotone zones with width ranging from several up to dozens of meters that stretch out in a strip around rocky local capes to a depth of 8–10 m. These zones pass through the supralittoral, littoral (pseudo littoral), upper sublittoral and further down to deep depth. Rocky areas of capes are characterized by massive settlements of macrophyte algae and bivalve’s representative of epifauna, while infauna organisms predominate on loose sediments. In the ecotone zones of the capes, favorable conditions occur for adult fish that inhabit the pelagic zone, rocky areas and loose sediments, as well as for fry and juvenile fish from different ecological groups. One hundred and twenty species of fish have been recorded in the biotopes of capes. The basis of the ichthyofauna consists of 35 species of bottom and near bottom-pelagic, mainly resident fish from 28 genera and 21 families. All fish species have ecological and morphological adaptations for living in ecotone zones of capes. In particular, their general color corresponds to the color of bottom substrates and they dig into loose sediments, have a flat body like rays and flatfishes, large pectoral fins, a large mouth and barbels for searching infauna preys, a snout for digging them out, and eyes located at the top of the head. Most species from the ichthyofauna of the capes can live in several different biotopes, but it is in the mixed landscapes of ecotone zones that they find the most favorable conditions.