Black Sea Ecosystem Research Articles

Irreversible starvation using RNA/DNA on lab-grown larval anchovy, Engraulis encrasicolus, and evaluating starvation in the field-caught larval cohort

The recruitment of anchovy Engraulis encrasicolus, the crucial forage fish in the Black Sea ecosystem, has drastically decreased in the last two decades, mainly due to overfishing. The wild-caught fertilized anchovy eggs were hatched and the larvae exposed to the different feeding levels to indicate the irreversible starvation criteria based on RNA/DNA, then the nutritional status of wild-caught larvae were evaluated. The newly hatched larvae had mean notochord length of 3.25 ± 0.04 mm and first feeding started on day 3 after hatching. The feeding levels applied to produce the irreversible starvation were fed control (FC), unfed control (UC), delayed first feeding for 1 (1DF), 2 (2DF) and 3 days (3DF). The whole body RNA/DNA ratio and the daily protein growth rate were individually analyzed. There were no survivors left in unfed group on day 6. Irreversible starvation (IS) occurred on the first day after first feeding which suggest the Black Sea anchovy larvae have a very low tolerance to starvation and the critical RNA/DNA ratio was 1.022 ± 0.20. The survival rate in the unfed control was similar to the other delayed groups. The highest daily protein growth rates were on day 6 with 43.45% for FC. Based on IS derived from RNA/DNA, 91% survival probability was detected in field-caught larvae. In future, irreversible RNA/DNA ratio can be used for monitoring and comparing of nutritional status and recruitment probability of different cohorts of the Black Sea anchovy larvae.

Technological Solution for the Treatment of Wastewater Resulting from Autochthonous Aquacultures in Order to Protect the Marine Water Quality

This paper depicts the research conducted at a micro-pilot scale on autochthonous cultures in order to develop adequate technological solutions for the treatment of wastewater resulting from shrimp cultures (Palaemonidae) that would ensure the protection of the Black Sea ecosystem and constitute an applicable tool for the development of aquaculture in Romania. The proposed objectives were attained by adopting an integrated system of marine cultures shrimps-mussels-macrophyte algae, followed by a conventional chemical treatment step using aluminium sulphate recovered from metallurgical slags. This system together with wastewater treatment ensures an optimum development of species and a minimum load of pollutants in the aquatic environment.

Macroalgal Fouling of Shells of <i>Rapana venosa</i> (Valenciennes, 1846) (Gastropoda, Muricidae) in the Northern Black Sea

Algal fouling of a gastropod predatory species Rapana venosa (Valenciennes, 1846) was investigated. R. venosa shells act as substrate for a great number of different fouling organisms, among which macroalgae are the most important. We studied the fouling communities on two ecomorphs (sandy and rocky) of R. venosa from the northern part of the Black Sea from 2008 to 2017. The fouling algae taxa were listed and the frequency of their occurrence on two ecomorphs of R. venosa was determined. 65 algae species were found, namely Chlorophyta – 20, Ochrophyta – 16 and Rhodophyta – 29 species. Typical alga species of sandy and rocky R. venosa ecomorphs and their assemblages’ composition was featured. It was found that the expansion of algae species distribution on the soft substrate is associated with R. venosa . During the period of R. venosa populations’ development this invasive species has become an important element of the Black Sea ecosystem which contributes to saving biological diversity of the benthic community due to formation and spreading of its consortium complexes.

Assessment of the Reactions of Algal Communities to Influence of Climatic Factors in the North-Western Black Sea Ecosystem

Assessment of the Reactions of Algal Communities to Influence of Climatic Factors in the North-Western Black Sea Ecosystem

Evolution of Future Black Sea Fish Stocks under Changing Environmental and Climatic Conditions

Here we present a case study towards producing quantitative scientific advice on the application of the EU Common Fisheries Policy (CFP) in the Black Sea. We provide estimates of fishing mortality rates at levels which will lead to rebuilding and maintaining stocks above biomass levels that could produce maximum sustainable yield (MSY) under the IPCC RCP4.5 future climate scenario together with the business as usual (BAU) river discharge scenario. In this study, we have implemented a coupled, basin-scale circulation-biogeochemical model and used its output to feed a food web model to test near-future changes that may be observed in the Black Sea ecosystem under the influence of contemporary fisheries exploitation conditions. In order to test model response to changes in climate and related drivers, the future climate scenario (2015-2020) simulation was compared to the present day (2000-2014) simulation. Likewise, to test the sensitivity of the higher trophic level food web model to changes in fishing pressure, a future estimate of fishing pressure was projected based on its respective contemporary value and applied to each fish stock. Using these models, fishing mortality rates that could produce the maximum sustainable yield (FMSY) in future years 2015-2020 and ensure the long-term recovery of the predatory fish stocks of the Black Sea are predicted. Future projections suggest that all fish stock will decrease in all the regions of the Black Sea except for sprat. Anchovy is expected to show the highest decrease in biomass. Analyses on FMSY estimates show that a significant reduction in fisheries exploitation is required for the sustainable management of the Black Sea ecosystems and the related services. This study, for the first time, presents future stock size, FMSY and MSY estimates for the Black Sea for 11 fish species. FMSY values are generally lower than estimates of the scientific, technical and economic committee for fisheries (STECF), mainly because of the explicit food web interactions that the modeling system allows to be considered.

Interannual variability of Danube waters propagation in summer period of 1992–2015 and its influence on the Black Sea ecosystem

The propagation of the Danube River plume has strong interannual variability that impacts the local balance of nutrients and the thermohaline structure in the western Black Sea. In the present study, we use a particle-tracking model based on satellite altimetry measurements and wind reanalysis data, as well as satellite measurements (SeaWiFS, MODIS), to investigate the interannual variability in the Danube plume pathways during the summer from 1993 to 2015. The wind conditions largely define the variability in the Danube water propagation. Relatively low-frequency variability (on periods of a week to months) in the wind stress curl modulates the intensity of the geostrophic Rim Current and related mesoscale eddy dynamics. High-frequency offshore wind-drift currents transport the plume across isobaths and provide an important transport link between shelf and offshore circulation. Inherent plume dynamics play an additional role in the near-mouth transport of the plume and its connection with offshore circulation. During the years with prevailing northeast winds (~ 30% of studied cases), which are usually accompanied by increased wind curl over the Black Sea and higher Danube discharge, an alongshore southward current at the NorthWestern Shelf (NWS) is formed near the western Black Sea coast. Advected southward, the Danube waters are entrained in the Rim Current jet, which transports them along the west coast of the basin. The strong Rim Current, fewer eddies and downwelling winds substantially decrease the cross-shelf exchange of nutrients. During the years with prevailing southeastern winds (~ 40%), the Rim Current is less intense. Mesoscale eddies effectively trap the Danube waters, transporting them to the deep western part of the basin. The low- and high-frequency southeastern wind-drift currents contribute significantly to cross-isobath plume transport and its connection with offshore circulation. During several years (~ 15%), the Danube waters moved eastward to the west coast of Crimea. They were transported on the north periphery of the mesoscale anticyclones due to prevailing eastward wind-drift currents. During the years with hot summers, a monsoon effect induced the formation of a strong anticyclonic wind cell over the NorthWestern Shelf (NWS), and the plume moved northward (~ 15%). Anticyclonic wind circulation leads to the Ekman convergence of brackish surface waters in the centre of the shelf and the formation of a baroclinic geostrophic anticyclone north of the NWS. This anticyclone traps the Danube waters and forces them to remain on the shelf for a long period of time. The impact of the propagation of the plume on the variability in chlorophyll a chlorophyll a in the NWS and the western Black Sea is analysed in this study based on satellite data.

Distribution and migration of 239+240Pu in abiotic components of the Black Sea ecosystems during the post-Chernobyl period

Distribution of 239,240Pu in abiotic components (water and bottom sediment) of the Black Sea ecosystems was studied during the post-Chernobyl period at different offshore and near-shore locations. The trends of these radionuclides accumulation by sediments were analyzed. The spatial-temporal changes in the 239,240Pu distribution as well as effective half-life for these radionuclides in the Black Sea surface water in deep-sea area are presented. The estimations of the average annual removal fluxes of the 239,240Pu into the bottom sediments were obtained. The Black Sea sediments were characterized by a higher 239,240Pu concentration factor (Cf ≈ n·104–n·106) and radiocapacity factor (F(239,240Pu) was about 99.9% on the shelf, 94.5–99.1% on deep-sea basin for silty and 94.6–98.9% on the shelf for sandy bottom sediments) as compared with Cf and F for 137Cs and 90Sr. Silty bottom sediments play the role of 239,240Pu main depot in the Black Sea ecosystem. The studied radioecological characteristics of Pu allowed us to define the type of plutonium biogeochemical behavior in the Black Sea as a pedotropic one. The results of this complex radioecological monitoring of 239+240Pu contamination in the Black Sea and their analysis makes it possible to understand the plutonium redistribution pathways which will enable to carry out the tracing of its migration within the ecosystems.

Seasonal changes in abundance, lipid and fatty acid composition of Calanus euxinus in the South-eastern Black Sea

Seasonal changes in abundance, lipid and fatty acid composition of Calanus euxinus Hulsemann, 1991 were analysed monthly during the period from March 2012 to February 2013. The highest abundance of C. euxinus was recorded in February (847 ind. m-3) during the sampling period. Female and male C. euxinus peaked in February (587 ind. m3, 169 ind. m-3, respectively). However, copepodites peaked in November (107 ind. m-3). Average total lipid content was determined as percentage (%) and per individual (mg ind-1). It was proportionally highest in February (7.03%) and lowest in September (3.02%). However, average lipid content per individual was highest in February (0.11 mg ind-1) and lowest in September and November (0.04 mg ind-1). Major fatty acids in C. euxinus were identified as 16:0, 16:1 n-7, EPA and DHA. ΣSFA, ΣMUFA, ΣPUFA and ΣHUFA were observed to be correlated with temperature. ΣSFA and ΣMUFA increasedwith the rise in temperature (r2=0.74, r2=0.73, p<0.05, respectively) whereas ΣPUFA and ΣHUFA increased as temperature decreased (r2=-0.73, r2=-0.80, respectively, p<0.05). Additionally, while ΣPUFA and ΣHUFA increased (r2=0.61, r2=-0.68, respectively, p<0.05), ΣMUFA decreased (r2=-0.68, p<0.05) as chlorophyll-a increased. It was observed that the degree of unsaturation increased as temperature decreased. Results of the study revealed that C. euxinus has rich lipid content as well as fatty acid composition and it plays an important role in the South-eastern Black Sea ecosystem functionalities especially having key role in energy fluxes to higher trophic levels.

Радиоэкологические закономерности перераспределения альфа-радионуклидов плутония в экосистеме Чёрного моря

Работа посвящена исследованию радиоэкологических процессов перераспределения альфа-радионуклидов плутония (239+240Pu) как основных дозообразующих техногенных альфа-радионуклидов в период после аварии на Чернобыльской АЭС. 239+240Pu ― долгоживущие радиоизотопы, количество которых накапливается в природных экосистемах от инцидента к инциденту. Радиотоксичность этих радионуклидов высока, и необходимы научно обоснованные подходы к оценке и прогнозу радиоэкологического состояния водоёмов, подверженных риску повторного радиоактивного загрязнения 239+240Pu. К таким водоёмам относится Чёрное море, как внутренне море, расположенное в регионе высокоразвитых стран, использующих ядерные технологии. Работа выполнена современными методами, основными из которых были: радиохимический анализ, альфа-спектрометрия и радиотрассерные технологии. В результате исследования выявлены радиоэкологические закономерности поведения плутония (Pu) в экосистеме Чёрного моря в постчернобыльский период. Определены количественные параметры миграции 239+240Pu в море: скорость осадконакопления в разных районах моря, период полууменьшения удельной активности поверхностных вод по 239+240Pu, фактор радиоёмкости для донных отложений, потоки плутония, уровни содержания 239+240Pu в компонентах экосистемы, коэффициенты накопления биотическими и абиотическими составляющими. Выявлены особенности биогеохимического поведения плутония в экосистеме Чёрного моря и указаны условия и процессы, их обуславливающие. Отмечены повышенная способность черноморских поверхностных вод к самоочищению в отношении 239+240Pu, короткий период пребывания плутония в поверхностных водах, относительно быстрое накопление плутония в осадках за счёт биогеохимической седиментации элемента, высокая концентрационная способность иловых донных отложений в отношении 239+240Pu, тип биогеохимического поведения плутония в экосистеме Чёрного моря.

Пространственное распределение и питание желетелых хищников в прибрежных районах Крыма в зимний период 2016 г.

Желетелые хищники ― важнейший компонент экосистемы Чёрного моря. Несмотря на многочисленные исследования различных аспектов их биологии (горизонтального и вертикального распределения, биоэнергетических показателей роста и трансформации энергии на организменном и популяционном уровнях) сведения о состоянии популяций и их функционировании в зимний период остаются крайне скудными. В настоящей работе численность, биомасса, размерная структура желетелых хищников (медузы Aurelia aurita, гребневиков Mnemiopsis leidyi, Beroe ovata и Pleurobrachia pileus) и интенсивность питания двух доминирующих видов (A. aurita, M. leidyi) исследованы на 17 станциях на шельфе Крыма в зимний период 2016 г. Сбор материала осуществляли модифицированной сетью Богорова ― Расса с диаметром входного отверстия 80 см, ячеëй 300 мкм, которой производили вертикальные траления от дна (10–100 м) до поверхности. Биомасса A. aurita, доминирующего в это время вида желетелых, изменялась в пределах 30–1990 г·м-2 с более высокими величинами в южных районах. Биомасса других видов желетелых была значительно ниже (максимальные величины — 170 г·м-2 для M. leidyi, и 60 г·м-2 для P. pileus). Высокая биомасса B. ovata (85 г·м-2 ), сравнимая с летней величиной, отмечена на одной из станций в западной части шельфа. Достоверных различий в биомассе отдельных видов желетелых по районам не выявлено, за исключением различий в биомассе B. ovata между западным и южным районами (p < 0.01). Популяции A. aurita и M. leidyi состояли из взрослых особей, в то время как большую часть популяции B. ovata составляли неполовозрелые гребневики длиной 20–30 мм. Основным видом пищи были велигеры двустворчатых моллюсков у A. aurita и различные стадии Copepoda— у M. leidyi. Cуточные рационы медуз составляли 0.009–0.107, M. leidyi — 0.02–0.28 % C тела и были значительно ниже пищевых потребностей животных в данных температурных условиях.

Long-term variations of the Black Sea dynamics and their impact on the marine ecosystem

Satellite altimetry data are used to study the long-term dynamics variability of the Black Sea from 1993 to 2013, its dependence on wind forcing and its impact on the marine ecosystem. Basin-scale dynamics have significant interseasonal and interannual variability. The most distinctly observed feature of the interannual dynamics variability is an almost twofold increase of the current kinetic energy from 2002 to 2012, based on anomaly weak values from 1998 to 2001. The amplitudes of a seasonal cycle of current velocity variability from 2002 to 2102 were two times higher than the amplitudes from 1998 to 2001. The seasonal variability of the current Mean Kinetic Energy (MKE) significantly varies among the years. Although usually maximal values of MKE are observed in winter and minimal values are observed in summer, the seasonal variability may exhibit two distinct peaks in spring and autumn, or even can be opposite with maximum values observed in warm period of a year.The variability of wind stress curl (or the Ekman pumping velocity) averaged over the basin is the main factor for the observed changes in the Black Sea dynamics. The analysis shows that the integral effect of the cyclonic wind curl causes water divergence in the centre of the basin, rising sea level gradients and Rim current intensification. The mean kinetic energy of the Black Sea currents follows the variability of Ekman pumping on seasonal and interannual time scales with a time delay of approximately two weeks. This lag is consistent with the estimated time that is required for water particles to drift from the central part to the basin periphery due to rising Ekman divergence.We employ an eddy-identification method to show that the interannual variability of the number of mesoscale eddies in the basin and their energy are opposite to the variability of the mean kinetic energy of the Black Sea currents and Ekman pumping over the basin. The number of eddies and their total energy decreased after basin scale current intensification in 2002. The reduction of the eddy horizontal transport and cross-shelf exchange caused a significant decline (~25%) of the surface chlorophyll a concentration in the deep part of the Black Sea after 2002. The largest decrease of the chlorophyll a concentration occurred over the continental slope, in the parts of the basin that are adjacent to the productive shelf areas. The eddy horizontal advection of nutrients can play a major role in conditioning the state of the Black Sea ecosystem on interannual time scales compared with a vertical entrainment of nutrients via winter convective mixing.

Mytilus Galloprovincialis - a Valuable Resource of the Black Sea Ecosystem

The Bivalvia family has been traced back to the beginning of the Paleosoic Era (The Devonian age) and have survived to this day, with very small changes. While more common in the Mediterranean, the Black Sea has been penetrated by representatives of the family, most frequently along the coastal area. Representatives of the Mytilus genus, mussels are very common in the seas and oceans of the world. Mytilus Galloprovincialis Lamarck has long been considered as being only a variety of Mytilus edulis Linne. Anatomical studies have shown that there are sufficient differences in order to accurately distinguish the two species. This paper presents a characterization of the Mytilus galloprovincialis mussel, which is a valuable resource existing in the Black Sea ecosystem.

Mytilus Galloprovincialis - a Valuable Resource of the Black Sea Ecosystem

The Bivalvia family has been traced back to the beginning of the Paleosoic Era (The Devonian age) and have survived to this day, with very small changes. While more common in the Mediterranean, the Black Sea has been penetrated by representatives of the family, most frequently along the coastal area. Representatives of the Mytilus genus, mussels are very common in the seas and oceans of the world. Mytilus Galloprovincialis Lamarck has long been considered as being only a variety of Mytilus edulis Linne. Anatomical studies have shown that there are sufficient differences in order to accurately distinguish the two species. This paper presents a characterization of the Mytilus galloprovincialis mussel, which is a valuable resource existing in the Black Sea ecosystem.

The Strategy of Use, Protection and Reproduction of Biological Resource Potential of the Black Sea

The forms of international cooperation in the fi eld of use and protection of biological resources of the Black Sea (the second half of the 20th century – early 21st century) is analyzed. It is concluded that now the Black Sea countries do not have the single legal base for exploitation of bioresource potential, including development of fi shery sector of economy, fi shery regulation and enforcement of environmental protection measures for conservation of biodiversity of the Black Sea ecosystem. The characteristics of present (after demise of the Soviet Union) situation in the context of exploitation and protection of biological resources of the Black Sea by fi shery industry of the Russian Federation are given. Some proposals regarding necessary strategy of marine natural resource management in the studied basin for the purpose of sustainable development are formulated. At that, the special attention is paid to development of commercial marine aquaculture.

Urgent Change in Management Measures Required to Save Turkish Fisheries from Collapse

Since the 1960s, the Black Sea ecosystem has experienced dramatic changes. Most noticeable is the almost complete absence of larger pelagic fish due to overfishing in the 1960s and 1970s. After the removal of these larger pelagic fish and the associated predation pressure, there was a rapid growth in populations of smaller pelagic fish, especially anchovy (Engraulis encrasicolis) and sprat (Sprattus sprattus), which comprised 75% of Turkish Black Sea reported catches in the 2000s [1].

Survey of viral haemorrhagic septicaemia virus in wild fishes in the southeastern Black Sea.

Species diversity in the Black Sea ecosystem has been declining rapidly over the last 2 decades. To assess the occurrence and distribution of viral haemorrhagic septicaemia virus (VHSV) in various wild fish species, a wild marine fish survey was carried out in 2009, 2010, and 2011. The pooled or individual samples of kidney, liver, and spleen of 5025 specimens, belonging to 17 fish species, were examined virologically using cell culture. The cells showing cytopathic effects (CPE) were subjected to ELISA and multiplex reverse transcriptase polymerase chain reaction (RT-mPCR), for VHSV and infectious pancreatic necrosis virus (IPNV), after blind passaging to determine the virus species causing CPE. The virus species and possibility of co-infection with IPNV were verified by the RT-mPCR developed in this study. Twelve species of fish (pontic shad Alosa immaculata, red mullet Mullus barbatus, three-bearded rockling Gaidropsarus vulgaris, black scorpionfish Scorpaena porcus, Mediterranean horse mackerel Trachurus mediterraneus, whiting Merlangius merlangus euxinus, stargazer Uranoscopus scaber, pilchard Sardina pilchardus, garfish Belone belone, round goby Neogobius melanostomus, thornback ray Raja clavata, and anchovy Engraulis encrasicolus) tested positive for VHSV Genotype Ie (VHSV-Ie). Except whiting, pilchard, and round goby, the rest are new host records for VHSV. The extent and spread of VHSV-Ie was significantly higher among bottom fish than among pelagic fish. Sensitivity and specificity of the RT-mPCR developed was sufficiently high, suggesting that this assay may be used for both diagnostic and surveillance testing. According to the RT-mPCR results, IPNV was not present in wild fish. These results support the hypothesis that the VHSV-Ie genotype, highly prevalent among fish species in the Black Sea, may have a serious impact on the population dynamics of wild fish stocks.

An indicator-based evaluation of Black Sea food web dynamics during 1960–2000

Four Ecopath mass-balance models were implemented for evaluating the structure and function of the Black Sea ecosystem using several ecological indicators during four distinctive periods (1960s, 1980–1987, 1988–1994 and 1995–2000). The results exemplify how the Black Sea ecosystem structure started to change after the 1960s as a result of a series of trophic transformations, i.e., shifts in the energy flow pathways through the food web. These transformations were initiated by anthropogenic factors, such as eutrophication and overfishing, that led to the transfer of large quantities of energy to the trophic dead-end species, which had no natural predators in the ecosystem, i.e., jellyfish whose biomass increased from 0.03gCm−2 in 1960–1969 to 0.933gCm−2 in 1988–1994. Concurrently, an alternative short pathway for energy transfer was formed that converted significant amounts of system production back to detritus. This decreased the transfer efficiency of energy flow from the primary producers to the higher trophic levels from 9% in the 1960s to 3% between 1980 and 1987. We conclude that the anchovy stock collapse and successful establishment of the alien comb-jelly Mnemiopsis in 1989 were rooted in the trophic interactions in the food web, all of which were exacerbated because of the long-term establishment of a combination of anthropogenic stressors.

Assessment of the modern state of the Black Sea ecosystem (Republic of Abkhazia)

Marine scientific research in the southern seas of Russia is a priority goal of the Southern Scientific Center of the Russian Academy of Sciences. In the last five years, we have carried out more than 30 expedi� tions to the Black Sea [1]. Despite the fact that the ecosystem of the Black Sea is considered well studied [2–6], detailed studies in the waters of the Republic of Abkhazia were carried out up to the middle of the 1980s and were completely terminated in 1991 owing to disintegration of the USSR and a military conflict between Abkhazia and Georgia. In June 2010, multi� disciplinary ecosystem studies were carried out for the first time in 20 years in the territorial waters and exclu� sive economic zone of the Republic of Abkhazia according to the suggestion of the leaders of the Republic of Abkhazia and the Rosneft Open Society. A background assessment of the modern ecological state of the Abkhazian waters was performed. These studies were directed to the conservation and repro� duction of the natural resources and termination of the negative influence of economic activity on the envi� ronment and liquidation of its possible consequences. The field studies were carried out according to the actual legal regularities and international obligations of Russia and the Republic of Abkhazia in the sphere of ecology and safe nature management in the Black Sea basin. The expedition studies within the Gudauta licensed site included hydrobiological works (hypo� neustone, zoo�, bacterio�, phyto�, ichthyoplankton, zoo�, and phytobenthos), ichthyological investiga� tions, and observation of birds and marine mammals according to the generally accepted methods at 15 sta�

Species composition of Black Sea marine planktonic copepods

This paper reviews the changes in the marine planktonic copepods of the Black Sea species' list from the beginning of taxonomic research to the present day. The study was based on the SESAME biological database, unpublished data, literature and data obtained during the course of the SESAME project. Comparisons were made with the Guidebook for Marine Fauna of the Black Sea and the Sea of Azov, which revealed changes both in the taxonomic status of some species and in the structure of the copepod community. The taxonomic status of two species (Acartia clausi small form and Centropages kroyeri pontica) and the nomenclature of two species (Oihona minuta and Calanus helgolandicus) have been changed. Three native species (Acartia margalefi, Oithona nana, and Paracartia latisetosa) have disappeared. Two non-indigenous copepods (Acartia tonsa and Oithona davisae) became established in the Black Sea ecosystem in the 1970s and 2000s, respectively. The success of their establishment was determined by biological features of the species and vulnerability of the native copepod community to invasions. It is highly probable that both species were introduced to the Black Sea by vessel ballast water. The hypothesis of “mediterranization” of the Black Sea fauna does not appear to hold true for zooplankton. Numerous claims of alien copepod species in the Black Sea remain largely unverified due to insufficient information. Data on newly discovered species of the Acartia genus are not authenticated. An updated list of marine planktonic copepods of the Black Sea is hereby presented.

Study of long-term variations in the Black Sea fields using an interdisciplinary physical and biogeochemical model

Using an interdisciplinary three-dimensional physical and biogeochemical model developed for the Black Sea, the long-term evolution of marine dynamics and ecosystem is investigated. The hydrophysical fields were calculated from a model of Black Sea circulation with assimilation of hydrographic survey and satellite measurement data from 1971 to 2001. The circulation model reproduces well processes of various scales in both space and time (particularly the seasonal course and interannual variability of main hydrophysical fields). The resulting flow fields are then used to calculate the long-term evolution of the components of the lower level of the food chain in the Black Sea ecosystem. The biogeochemical model used in the calculations is based on the nitrogen cycle and includes a parameterization of the main biological and chemical interactions and processes in the upper layer of the Black Sea. The numerical experiments indicated that the biogeochemical component of the model rather successfully reproduces the main features and evolution trends in the Black Sea ecosystem for the period under consideration: the growth in the phytoplankton biomass during eutrophication and changes in seasonal cycles of the main ecosystem components. Also, the hydrophysical processes were shown to be important for a reliable reproduction of long-term changes in the ecosystem.