Seasonal Changes In Zoobenthos In The Northwestern Part Of The South Caspian

Abstract

The article is devoted to seasonal changes in zoobenthos in the northwestern part of the South Caspian. During research in the northwestern part of the South Caspian, 60 species belonged to 10 taxonomic groups. Crustaceans prevail by the number of species, accounting for 45.0% of the total number of species. Worms occupy second place in benthos - 31.7%, followed by molluscs - 21.7%. The maximum number of species was recorded in the spring-summer season (from 52 to 60 species), and the minimum – in the autumn season (43 species). The average annual biomass was 101.27 g / m2, with a population of 816 individuals / m2. The maximum development of macrozoobenthos organisms was noted in summer (118.91 g / m2), the minimum in autumn (77.12 g / m2). Molluscs are the dominant group (67.7%) from the weight of the biomass of benthos in the environment of macrozoobenthic organisms in terms of biomass, crustaceans are in second place in terms of biomass (52.0%), and amphipods are in third place (5.0%). In terms of species and quantity, the fauna of the ooze-shell biotope is most abundant, where the total biomass of zoobenthos was 129.17 g / m2, with with an abundance of 940 species / m2. Among these animals on the biomass of benthos, decapods are in second place - 17.9%. The quantitative distribution of zoobenthos by depth is not the same. In the coastal zone (10-25m), the average biomass of benthos was 115.86 g / m2, at a depth (25-50m) - 126.99 g / m2, at a depth (50-100m) - 85.52 g / m2 and at a depth (100-200) - 76.71 g / m2. At all depths, the basis of zoobenthos is obtained from the biomasses of these animals.