Concentration and production of bacteria and bacterial destruction in the photic layer of the Sodruzhestvo Sea area, Southern Ocean

Bacterioplankton in the photic layer of the Sodruzhestvo Sea area and adjoining waters consists in summer primarily of cocci, with fractions smaller than 2 ?m predominating. The average abundance and biomass of microorganisms are 427 thousand cells/ml and 438 mg C/m**2, with ranges of 150-1770 thousand cells/ml and 221-1146 mg C/m**2. The average daily production and bacterial destruction increase from 49 and 104 mg C/m**2 at the beginning of the growth period to 85 and 180 mg C/m**2 in the middle of the period and remain at this level till the end. Despite low rate of increase (daily P/B coefficient averages 0.12), because of its high abundance bacterioplankton in Antarctic waters plays a major role in destruction of organic matter, accounting for 60-85% of energy consumed by heterotrophs

Структура и функционирование антарктических морских прибрежных экосистем в условиях природного и антропогенного загрязнения

На основе экологического мониторинга получено целостное представление о структурной организации водной экосистемы в малоизученной прибрежной зоне, прилегающей к Украинской Антарктической станции. Структура и функционирование биоты определяются специфической ответной реакцией её экологически разных элементов на ряд лимитирующих факторов. Известная несбалансированность антарктического планктона по трофическим взаимоотношениям сообществ усугубляется кратковременностью вегетационного периода, активным обменом вод прибрежья с открытым океаном и загрязнением среды. В результате при обилии фито- и бактериопланктона слабое развитие получает мезозоопланктон, а значительная доля первичного вещества поступает на дно, обусловливая интенсивное развитие донной фауны. Выявлена аккумуляция тяжелых металлов разной токсичности в организмах массовых видов фито-зообентоса, макропланктона и рыб. Ингибирующее влияние загрязнения проявляется в подавлении процесса воспроизводства криля, популяция которого является зависимой, пополняемой приносом из других районов. Интенсивность этого пополнения и локализация максимумов его численности определяют кормовые условия организмов-потребителей рачка.The long-term environmental monitoring has provided the insight into the integral structure of marine ecosystem in a poorly investigated coastal area in the vicinity of the Ukrainian Antarctic Station. The structure and function of the local biota are the specific response of environmentally different involved elements to a series of limiting factors. Very short Antarctic vegetation season, the intensive coastal and deep-sea water exchange and environmental pollution add to unbalanced food relations of Antarctic plankton. As a result, despite abundant phyto- and bacterioplankton the fraction of mesozooplankton is underdeveloped and a large portion of primary matter sinks onto the sea floor thereby stimulating intensive growth of bottom organisms. Mass phyto- and zoobenthos and macroplankton species and fishes accumulate toxic heavy metals. The pollution inhibits normal reproduction of krill, the population recruitment of which is now owing to krill aggregations brought from other areas by sea currents. Krill recruitment rate and the local abundance maximums are the determining food conditions for natural consumers of the krill

Интегральная оценка загрязненности донных осадков в прибрежной и открытой частях Черного моря

Исходными данными для работы послужили результаты трех комплексных сезонных съемок в 1992 году на судах Украинского научного центра экологии моря (УкрНЦЭМ, Одесса) в северной половине Черного моря. Выявлены основные поллютанты, вносящие наибольший вклад в уровень интегрального загрязнения моря. Превалирующими поллютантами донных отложений моря на глубинах от 9 до 2195 м, концентрации которых превышала ПДК, были нефтепродукты НП, ДДТ и его метаболиты и ГХЦГ. Это обстоятельство должно учитываться при выборе стратегии токсикологического мониторинга Черного моря с целью его оптимизации.In 1992 the Ukrainian Research Centre of Marine Ecology (UkrRCME) organized several marine expeditions to the northern Black Sea; materials collected during three complex seasonal surveys are used in this work. It was revealed the main pollutants that make the impotent contribute to the integral level of contamination of the sea. At depths ranged from 9 to 2195 m pollutants deposited in the sea bed were mainly total petroleum hydrocarbons (TPH), DDT and its metabolites, and HCCH, the quantities of which were greater than maximum allowable concentrations (MAC). This fact should be considered when choosing a strategy of toxicological monitoring of the Black Sea for the purpose to optimize it

State of the Marine Ecosystem Near the Mouth of the Agoy River (Black Sea)

Aim. To study the state of the marine ecosystem of the recreational‐tourist zone of the Caucasian sector of the Black Sea through the example of a beach near the mouth of the Agoy River.Material and Methods. Phytoplankton, heterotrophic bacterioplankton, infusoria, holoplankton, meroplankton, ichthyoplankton, zoobenthos of loose bottom sediments and hydrochemistry samples of the water and bottom sediments were collected in June 2012 on three sections from the mouth of the Agoy River to the coastal runoff zone (depths 2.5–7.5 m). The identification of species of plankton and of the zoobenthos and of the chemical parameters of water and sediments was carried out according to standard methods. Results. It was revealed that most of the beach area, where psammophilic biocenoses of Lucinella divaricate and Chamelea gallina (Bivalvia) were located, was in satisfactory condition. An increase in the density of Lucinella divaricate, a rare species in the late 1990s, was noted. In the runoff zone, there was observed the appearance of cyanobacteria and the suppression of zoobenthos, expressed through the replacement of mollusc biocenoses by the biocenosis of the polychaete, Capitella capitate, with a biomass two orders of magnitude lower than the average for the area. High numbers of heterotrophic bacterioplankton (4.5 million cell/ml) and infusoria (64 million ind./m3) could indicate bacterial contamination of this zone. The negative impact of waste water on plankton is manifested in a decrease in the population of netted zooplankton, their abnormal development, and the increasing role of microheterotrophs.Conclusions. The results obtained give an image of the state of marine coastal ecosystems of recreational‐tourist and cordoned areas of the Caucasus and can be useful for the further monitoring of this region

Distribution and Demography of Antarctic Krill and Salps in the Atlantic Sector of the Southern Ocean during Austral Summer 2021–2022

The study aimed to investigate krill (Euphausia superba) and salp (Salpa thompsoni) populations in the Atlantic sector of the Southern Ocean in January and February 2022. Samples were obtained to measure the abundance, biomass and distribution patterns of krill and salp. Sex differences and feeding habits of the Antarctic krill were determined. The dependence of the physiological state of the studied aquatic organisms on changes in environmental parameters was analyzed. Current data on the association of the dynamics of hydrometeorological parameters and processes with the distribution of chlorophyll a, krill, and salp were obtained. It was established that, at numerous stations, the biomass of salps prevailed over krill. The result indicates the replacement of the Antarctic krill populations by gelatinous zooplankton. The obtained results allow assessment of the biological resource potential in the studied region based on the analysis of the samples collected

Current Assessment of Water Quality and Biota Characteristics of the Pelagic Ecosystem of the Atlantic Sector of Antarctica: The Multidisciplinary Studies by the Institute of Biology of the Southern Seas

Comprehensive studies of the ecosystem of the Atlantic sector of the Antarctic were carried out in the period between 2020 and 2022, during the 79th and 87th sea expeditions on the R/V “Akademik Mstislav Keldysh”. Concentrations of soluble forms of 15 trace elements, except Mo, in surface waters of the Southern Ocean were matched the lower limit of their background concentrations in oceanic waters. A high spatial variability of chlorophyll a—an indicator of phytoplankton biomass, which is the main food object of the Antarctic krill—was revealed. In the Bransfield Strait, the abundance of bacterioplankton exhibited a weak relationship with water temperature and a pronounced dependence on chlorophyll fluorescence. It was determined, by using the bioluminescence method, that the largest concentrations of larvae and juveniles of krill were noted in the Bransfield Strait, on the shelf of the Antarctic Peninsula. Against the background of a decline in krill abundance in recent years, there has been an intensive development of Salpa thompsoni, the main food competitor of krill. New data on the distribution of mesoparasitic copepods on endemic fish of the Southern Ocean were also obtained, and their pathogenic effect on the body of fish hosts has been revealed