Abstract
The fields developing on the shelf of the northern Caspian Sea, which belongs to the shallow water zone, are where the breeding and nagulation of semi-passable fish mainly occurs. In this regard, studies of bottom sediments where macrozoobentos is concentrated, which is a feed of benthic fish, are a problem that requires research into the state of not only pollution of bottom sediments but also the state of macrozoobenthos. In this regard, this article is aimed at detecting the state of pollution of bottom sediments by heavy metals and the state of macrozoobenthos, the number and biomass distribution. The leading approach to the study of this problem is the «The guide to methods of hydrobiological analysis of surface waters and bottom sediments» and the «The methodological manual for hydrobiological fisheries research of Kazakhstan reservoirs». The article presents the results of the state of pollution of bottom deposition by heavy metals on the structures of Kashagan, Aktoty, Kairan and the number and species composition of macrozoobenthos. The article revealed that the content of metals in bottom sediments in the studied areas was quite stable and mainly changed in a small range in all seasons of 2019. The species composition of macrozoobenthos was quite homogeneous throughout the surveyed area of the sea. The number of bottom invertebrates varied within relatively small limits, with a more expressed range of biomass fluctuations. Keywords: bottom sediments; Kashagan; Aktoty; Kairan; heavy metals; macrobenthos.