THE CURRENT CONDITION OF THE MACROZOOBENTOS OF THE KHADZHIBEY ESTUARY (NORTHERN BLACK SEA REGION)
DOI:
https://doi.org/10.31861/biosystems2024.03.313Keywords:
macrozoobenthos, quantitative parameters, Khadzhibey estuary, Northern Black Sea regionAbstract
The qualitative composition and features of the quantitative development of the macrozoobenthos of the Khadzhibey estuary, located in the northern Black Sea region near the city of Odessa, have been determined. The material was collected in the spring and autumn periods of 2021–2023 at 10 stations evenly distributed throughout the estuary. It was determined that the water temperature in the estuary in the spring of 2021–2023 was 15,6–23,4 °C, and in autumn – 26,3–29,7 °C. Water salinity during the same period ranged from 4,88 to 6,32 ‰ in spring, and from 6,15 to 6,87 ‰ in autumn. The depth at all studied stations did not exceed 1,5 m. In the macrozoobenthos community of the Khadzhibey estuary, 5 species of invertebrates were identified, namely: the polychaete Alitta succinea (Leuckart, 1847), the shrimp Palaemon elegans Rathke, 1837, the amphipod Gammarus insensibilis Stock, 1966, the gastropod Hydrobia acuta (Draparnaud, 1805) and the chironomid Chironomus plumosus (Linnaeus, 1758). Representatives of decapods and amphipods can be classified as permanent species of the macrozoobenthos community of the estuary, since their occurrence P was 50–70 %. The polychaete was classified as a rare species (P=33,3–42,8 %), and the gastropod – as a occasional species (P=14,3 %). All these invertebrates are eurybiont species that are able to survive with low salinity of water and a significant deterioration in its quality due to the long term discharge of insufficiently treated wastewater from the city of Odessa into the estuary. Of all the identified species, only the chironomid Ch. plumosus had 100% occurrence. This species achieved the greatest quantitative development in the conditions of the estuary. So in the spring of 2021, the average abundance of Ch. plumosus was 6765±2145 ind.·m-2, which is 98,3 % of the total abundance of all macrozoobenthos, and the average biomass was 44,15±18,09 g·m-2 (87,8 %). Due to this dominance of one species, the Khadzhibey estuary continues to transform into a “chironomid” reservoir. The use of the ABC-method showed that the macrozoobenthos community of the Khadzhibey estuary is in a stress condition. In general, within the framework of studies 2021–2023 the species richness of macrozoobenthos in the estuary has decreased by half compared to 2002–2003.
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