MACROZOOBENTHOS OF COASTAL BIOTOPES OF THE ODESSA SEA REGION (BLACK SEA)

Abstract

The data on the structure of macrozoobenthos of rock and sand biotopes in the Odessa Sea Region at a depth of up to 8 m are presented. A total of 91 taxa of macrozoobenthos were recorded in the study area: 31 annelida, 23 molluscs, 29 crustaceans and 8 representatives of other groups. The average density of fauna amounted to 25,350±4,983 ind.∙m-2, biomass – 3,462.2±570.1 g∙m-2. The highest indicators of average density (16,394±4,020 ind.∙m-2) were noted for Mytilaster lineatus (Gmelin, 1791), biomass (2,519.6±454.2 g∙m-2) for Mytilus galloprovincialis Lamarck, 1819. In terms of density (74 %) and biomass (95.6 %), mollusks predominated; among the trophic groups – sestonophages (77.9 % and 98.9 %, respectively). We revealed 83 taxa in the stone biotope, and 58 taxa in the sand biotope; the coefficient of similarity (Zhakkara-Alʹokhina) was 54.9 %. The average density of benthos in the biotope of stones were 27 times higher (54,027±10,558 ind.∙m-2) than in the biotope of sand (2,008±659 ind.∙m-2). The average biomass in the biotope of stones (7,648.3±847.9 g∙m-2) was 137 times higher than in the biotope of sand (55.7±26.9 g∙m-2). In both biotopes, annelida and crustaceans predominated in the number of taxa; in terms of number (75.4–43.3 %) and biomass (95.6–88.3 %) molluscs dominated. Among the trophic groups in both biotopes, detritophages prevailed in the number of taxa, and sestonophages prevailed in density and biomass. The proportion of invasive species was 7.8–1.1 % of the density and 2.9–8.8 % of the biomass. In the biotope of stones, sessile hydrobionts of epifauna prevailed in terms of density and biomass, while in the biotope of sand, vagil organisms of infauna prevailed. Biocenoses of M. galloprovincialis and M. lineatus were identified in the stone biotope, and biocenosis of Chamelea gallina (Linnaeus, 1758) in the sand biotope. The highest indicators of the number of taxa (76), average density (74,147±13,133 ind.∙m-2) and biomass (10,635.2±478.2 g∙m-2) were noted in the biocenosis of M. galloprovincialis, and the lowest (31 taxa, 4,024±2,418 ind.∙m-2 and 133.6±35.2 g∙m-2) – in the biocenosis of Ch. gallina.