Study of Ecosystem of the Sukhum Bay With Emphasis Anthropogenic Impact, Abkhazian Black Sea Coast

Abstract

For the first time in thirty years, baseline comprehensive studies plankton and zoobenthos of the Sukhum Bay were conducted and an assessment of its current environmental status was given. The summer phytoplankton abundance of the port of Sukhum was represented mainly by coccolithophorids Emiliania huxleyi and diatoms algae, among the latter, the common species in polluted or eutrophic brackish waters were recorded. The presence of euglenic algae and cyanobacteria indicates a higher nutrient status, pollution and desalination of the sea area. The alien species Peridinium quinquecorne Abé (Dinophyceae) was recorded in the Abkhazian coastal waters for the first time. Totally, 7 species of tintinnids belonging to 3 genera Favella, Tintinnopsis, Eutintinnus were established from the Sukhum Bay. Among them, the non-indigenous species Eutintinnus tubulosus and E. apertus were noticed. Tintinnid ciliates accounted for ca. 5% of total ciliates abundance. The values of the abundance of aloricated ciliates were comparable to the values obtained from offshore of bays and ports of the northeastern Black Sea. As the pressure of predators is reduced the well-pronounced peaks of holo- and meroplankton biomass were recorded in the last summer – early autumn. A significant part of total holoplankton biomass – 66.5 % (up to 1.1 g/m3) was composed of cladocerans Penilia avirostris. The meroplankton was dominated by larvae of bivalve mollusks Mytilaster lineatus, polychaetes Polydora cornuta and cirripede barnacle Amphibalanus improvisus. The number of meroplankton in the open Sukhum port was 10–15 times lower above than a level of values obtained for ports and bays of the northeastern Black Sea. Among ichthyoplankton, the dominant species were Mullus barbatus ponticus, Diplodus annularis, Trachurus mediterraneus, Engraulis encrasicholus and Sciena umbra. Mean abundance of ichthyoplankton in vertical catches was 5–10 times lower than in offshore of Anapa and Gelendzhik of the northeastern Black Sea. And the proportion of dead eggs was 2 – 3 times higher than areas of these resort cities. The composition of macrozoobenthos was drastically depleted and resembled that of the polluted port complexes of the northeastern Black Sea. Heteromastus association dominated in mud bottom sediments. Among spionid polychaetes, the worst invaders Streblospio gynobranchiata and Polydora cornuta have been recorded in soft bottom communities. Depletion of benthic communities, loss from the structure of the trophic web of the macrophyte community and appearance of cyanobacteria and a new alien species in the planktonic and benthic communities leads inevitably to imbalance of the structure of the Sukhum port ecosystem.

Diversity and abundance of phytoplankton in Bone Bay, South Sulawesi, Indonesia and its relationship with environmental variables

“…Several research results carried out in bay waters, such as in Hurun Bay, have a high abundance of diatom species, especially Chaetoceros (Sidabutar et al 2022), also Thalassionema and Rhizosolenia in the Bay of Bengal, Bangladesh (Islam et al 2021). Similar results were also found in Tiksi Bay in the Russian Arctic (Barinova et al 2023), Georgian Bay in Canada, Sukhum Bay on the Abkhazian Black Sea coast (Selifonova et al 2019), and Jiaozhou Bay in China .…”

The Status of Plankton Algocenosis in the North-East Part of the Black Sea (2011–2020)

“…В ходе исследования 2-8 % от общего обилия фитопланктона было сформировано эвгленовыми водорослями (родов Eutreptia, Euglena) и цианобактериями (Oscillatoria, Lyngbya). Присутствие этих видов указывает на более высокий уровень питательных веществ, загрязнение и опреснение морской акватории [5]. В составе фитопланктона устьевых участков рек побережья Абхазии было выявлено 84 таксона рангом ниже рода, среди них диатомовых -44, зеленых -17, эвгленовых -10, других -13 [6].…”

Response of the Coastal Phytoplankton Community to the Runoff from Small Rivers in the Northeastern Black Sea

“…In the zone of influence of the mesotrophic Tuapse River, Thalassiosira spp., Leptocylindrus minimus, Chaetoceros wighamii, Pseudo-nitzschia pseudodelicatissima, Tripos muelleri, Cochlodinium sp., Prorocentrum cordatum, P. micans, Scrippsiella acuminata, Gymnodinium sp., young peridineae, and Emiliania huxleyi prevailed. All these species are typical of the Black Sea coastal flora and have been noted in previous studies of phytoplankton in the NE Black Sea [29,36,37,40,42]. The presence of the dinoflagellate Alexandrium tamarense and diatom Pseudo-nitzschia pseu-dodelicatissima in photosynthetically active states is noteworthy because of their possibilities of producing toxins, ASP (amnesic shellfish poisoning) and PSP (paralitic shellfish poisoning) [16,37].…”

“…Direct phytoplankton studies in the nearshore Caucasian part of the Black Sea are numerous [36][37][38][39][40][41][42], investigating the species composition, seasonal variability of the abundance and biomass, the presence of potentially toxic species in communities, the appearance of new species in the community, and the impact of port conditions on plankton phytocenoses. However, the impact of abiotic factors (changes in temperature, salinity or nutrient supply) on the phytoplankton community remains unstudied.…”