Оценка влияния выращивания товарной рыбы в садках на экологическое состояние водоема

Abstract

Growing a large mass of hydrobionts in a limited area (cage fish farming) entails a local increase in the load on the ecosystem from additional organic matter. In connection with the high growth rates of development of cage farms in various open natural water bodies, it is necessary to improve the system for monitoring their impact on aquatic biocenoses. The quality of surface waters and bottom sediments of the Ermakovskiy Bay of the Ust-Kamenogorsk Reservoir has been assessed in the of operation area of the cage farm Shygys, LLP. According to the zooplankton indices, the Pantle-Bukk saprobity index in the modification of Sladechek was used, the oligochaete index was used for macrozoobenthos. The studies were carried out at three stations: 200 m upper the bay (conditionally background station); at the cage line (reflects the local impact of the fish farm on the reservoir); 200 m lower the bay (reflects the overall impact of the enterprise on the reservoir associated with the removal of pollutants). As a result of the research, it was found that before the start 
 of cage fish farm operation the quality of water and bottom sediments at all points of the study corresponded to the “clean” category. A year after the launch of the enterprise a decrease in the taxonomic richness of zooplankton was noted, which indicates a slight deterioration in the quality of surface waters. In the fourth year of cage farm operation the saprobity indices near the cage line grew up to 1.8, and lower the bay - to 1.6, which indicates a local deterioration of the surface waters quality (class III, moderately polluted water). A similar situation is also characteristic of benthic communities of invertebrates. In 2017, at all three research stations, and in subsequent years only at a conditionally background station bottom sediments were characterized as clean. In 2019-2021 the pollution of bottom sediments was on the rise in the cage zone and below the Yermakovskiy Bay. The values of the oligochaete index increased from 14-20 to 58-75%. In 2019, bottom sediments were rated as class IV (contaminated), and in 2021 - as class V (dirty). On the results of the studies there were developed the corrective measures for reducing the anthropogenic load on the open natural reservoir. In the future monitoring the changes in qualitative and quantitative indicators of hydrobionts in the operation area of fish cage farms will allow local monitoring of water quality and timely adjustment of reclamation and fish breeding activities.