scholarly journals Climate change induced a new intermittent regime of convective ventilation that threatens the Black Sea oxygenation status

2020 ◽  
Author(s):  
Arthur Capet ◽  
Luc Vandenbulcke ◽  
Marilaure Grégoire
Keyword(s):  
Black Sea ◽  
Regime Shift ◽  
Cold Water ◽  
The Black Sea ◽  
Leading Role ◽  
Oxygen Budget ◽  
Intermediate Layers ◽  
Water Formation ◽  
Oxygenation Status

Abstract. The Black Sea is entirely anoxic, except for a thin (∼ 100 m) ventilated surface layer. Since 1955, the oxygen content of this upper layer has decreased by 44 %. The reasons hypothesized for this decrease are, first, a period of eutrophication from mid 70's to early 90's and, second, a reduction in the ventilation processes, suspected for the recent years. Here we show that the Black Sea convective ventilation regime has been drastically altered by atmospheric warming during the last decade. Since 2008, the prevailing regime is below the range of variability recorded since 1955, and is characterized by consecutive years during which the renewal of intermediate waters does not occur. Oxygen records from the last decade indicate a clear relationship between cold water formation events and oxygenation status at different pycnal levels, suggesting a leading role of convective ventilation in the oxygen budget of the upper intermediate layers. We thus suggest that this regime shift has a significant impact on the oxygenation structure of the Black Sea and on its biogeochemical balance.

scholarly journals A new intermittent regime of convective ventilation threatens the Black Sea oxygenation status

2020 ◽  
Vol 17 (24) ◽  
pp. 6507-6525
Author(s):  
Arthur Capet ◽  
Luc Vandenbulcke ◽  
Marilaure Grégoire
Keyword(s):  
Black Sea ◽  
Cold Water ◽  
The Black Sea ◽  
Intermediate Water ◽  
Oxygen Budget ◽  
Intermediate Layers ◽  
Oxygenation Status ◽  
The Impact ◽  
The Relationship

Abstract. The Black Sea is entirely anoxic, except for a thin (∼ 100 m) ventilated surface layer. Since 1955, the oxygen content of this upper layer has decreased by 44 %. The reasons hypothesized for this decrease are, first, a period of eutrophication from the mid-1970s to the early 1990s and, second, a reduction in the ventilation processes, suspected for recent years (post-2005). Here, we show that the Black Sea convective ventilation regime has been drastically altered by atmospheric warming during the last decade. Since 2009, the prevailing regime has been below the range of variability recorded since 1955 and has been characterized by consecutive years during which the usual partial renewal of intermediate water has not occurred. Oxygen records from the last decade are used to detail the relationship between cold-water formation events and oxygenation at different density levels, to highlight the role of convective ventilation in the oxygen budget of the intermediate layers and to emphasize the impact that a persistence in the reduced ventilation regime would bear on the oxygenation structure of the Black Sea and on its biogeochemical balance.

Water Masses in the Black Sea as Seen by Profiling Floats. A revisit of the role of winter, slope and geothermal convectio.

2021 ◽  
Author(s):  
Emil Stanev ◽  
Boriana Chtirkova ◽  
Elisaveta Peneva
Keyword(s):  
Black Sea ◽  
Intermediate Layer ◽  
Cold Water ◽  
Density Ratio ◽  
Water Masses ◽  
The Black Sea ◽  
Convective Layer ◽  
First Time ◽  
Main Pycnocline

<p>More than 6000 profiles from profiling floats in the Black Sea over the 2005-2020 period were used to study the ventilation of this basin from the top to the very bottom. In the upper layers and in the main pycnocline, water masses show a strong interannual variability following intermittent events of cold water formation. The density ratio decreased three times during the last 15 years, revealing the decreasing role of temperature in the vertical layering of the Black Sea halocline. The deep transition layer (DTL) between 700 and 1700 m acts as an interface between the baroclinic layer and the largest bottom convective layer (BCL) of the world oceans. On top of DTL are the warm intermediate layer (WIL) and deep cold intermediate layer (DCIL). They both showed strong trends in the last fifteen years due to warmer climate and intensification of warmer intrusions from Bosporus. A “salinity wave” was detected in 2005-2009 below ~1700 m, which evidenced for the first time the penetration of gravity flow from Bosporus down to the bottom. The layering of water masses was explained as resulting from the different distribution of sources of heat and salt, double duffusion and balances between the geothermal and salinity flows in the BCL.</p>

scholarly journals Biotic links in the fouling community of Odessa Bay (Black Sea)

2018 ◽  
Vol 26 (1) ◽  
pp. 24-29
Author(s):  
A. Y. Varigin
Keyword(s):  
Black Sea ◽  
Ecosystem Engineer ◽  
Three Dimensional ◽  
The Black Sea ◽  
Fouling Community ◽  
The Core ◽  
Leading Role ◽  
Food Reserves ◽  
Sessile Organisms

This paper reveals the character of the biotic links between the various organisms that compose the fouling community of Odessa Bay (Black Sea). The fouling community of solid substrates is formed by 62 species of invertebrates and 12 species of macrophytes. The edificator species of the community is the Black Sea mussel Mytilus galloprovincialis Lamarck, 1819. The environment-forming role of the mussel, which is represents the core of the corresponding consortia, was examined. The leading role of sessile organisms in the formation of a superorganismic structure that significantly modifies the properties of the environment was revealed. Together with the mussel, this structure is formed by the bivalve mollusc Mytilaster lineatus (Gmelin, 1791) and the barnacle crustacean Amphibalanus improvisus (Darwin, 1854). The proportion of sessile organisms accounts for 24.6% of the total number of species in the community. In this case, they significantly dominate in relative abundance and biomass (78.9% and 98.8%, respectively). The mussels during the process of growth form complexly organized druses, which are peculiar three-dimensional formations, consisting of mussels of different sizes, fastened together with a substrate by an entire network of strong byssus threads. These formations increase the level of heterogeneity of the substrate and increase the variety of available habitats for other animals. The aggregate of these druses is a kind of sedimentary trap in which particles of nutritive detritus accumulate. The availability of accessible habitats, convenient shelters and food reserves attracts various species of invertebrates to the community. Around the core of the consortia a cluster of organisms formed associated with edificator species. An important role is played by trophic links between different mobile organisms and the phyto-component of the community. The ability of the Black Sea mussel to condition the environment, creating favourable conditions for the development of other organisms, characterizes it as an autogenic ecosystem engineer. Trophic and mediopathic links between the organisms that compose the fouling community go beyond it and extend to the inhabitants of the pelagic environment.

Role of suspended matter in controlling beryllium-7 (7Be) in the Black Sea surface layer

2021 ◽  
pp. 103513
Author(s):  
Dmitrii A. Kremenchutskii ◽  
Gennady F. Batrakov ◽  
Illarion I. Dovhyi ◽  
Yury A. Sapozhnikov
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Suspended Matter ◽  
Sea Surface ◽  
The Black Sea

Georgian Historians and the Ideological Confrontation Between East and West

2021 ◽  
Vol 30 (1) ◽  
pp. 153-164
Author(s):  
George Gotsiridze
Keyword(s):  
Soviet Union ◽  
Cultural Values ◽  
Black Sea ◽  
The Black Sea ◽  
Black Sea Region ◽  
The Soviet Union ◽  
Long Time ◽  
Science And Culture ◽  
East And West

The work, on the one hand, highlights the mission of Europe, as an importer of knowledge, which has for centuries been the center of gravity for the whole world, and, on the other hand, the role of the Black Sea Region, as an important part of the Great Silk Road, which had also for a long time been promoting the process of rap-prochement and exchange of cultural values between East and West peoples, until it became the ‘inner lake’ of the Ottoman Empire, and today it reverts the function of rapproching and connecting civilizations. The article shows the importance of the Black Sea countries in maintaining overall European stability and in this context the role of historical science. On the backdrop of the ideological confrontation between Georgian historians being inside and outside the Iron Curtain, which began with the foundation of the Soviet Union, the research sheds light on the merit of the Georgian scholars-in-exile for both popularization of the Georgian culture and science in Eu-rope and for importing advanced (European) scientific knowledge to Georgia. Ex-change of knowledge in science and culture between the Black Sea region and Europe will enrich and complete each other through impact and each of them will have unique, inimitative features.

scholarly journals Ecological interrelations of Rapana venosa (Gastropoda: Muricidae) with ichthyofauna in the Black Sea

2016 ◽  
Vol 1 (4) ◽  
pp. 76-77
Author(s):  
I. P. Bondarev
Keyword(s):  
Black Sea ◽  
Marine Ecosystem ◽  
Fish Fauna ◽  
The Black Sea ◽  
Sandy Bottom ◽  
Rapana Venosa ◽  
New Information ◽  
Bottom Zone

Systematic monitoring of ecologically significant species – predatory mollusc Rapana venosa Valenciennes, 1846 populations – is an important part of the Black Sea monitoring. The study of the role of R. venosa in contemporary marine ecosystem is of considerable interest. In June-September 2015-2016 the study of consorting relations of rapana was conducted in situ with a parallel sampling by diver. In the course of research new information about the interaction of R. venosa with the fish fauna has been obtained. Of particular importance for fishes is the presence of rapana in the sandy bottom zone, where there are no natural shelters, and food resources are limited. The most important for the fish is the presence on the rapana shells of algal fouling and epiphyton. The shells of invader – R. venosa – and its fouling create additional opportunities for the survival of some fish fauna representatives juveniles of the Black Sea. The data obtained extend the concepts of ecological role of mollusc – invader R. venosa, as well as the ecology and ethology of several fish species.

The Role of the Black Sea Commission in the Sustainable Management of the Marine Living Resources

2015 ◽  
pp. 306-326
Author(s):  
Iryna Makarenko
Keyword(s):  
Black Sea ◽  
Marine Environment ◽  
Sustainable Management ◽  
Institutional Structure ◽  
The Black Sea ◽  
Global Level ◽  
Current Trends

In this chapter, the role of the Black Sea Commission in the preservation of marine environment will be considered. Particular emphasis will be placed on the activities related to management of the marine living resources, the legal gaps in the documents and institutional structure, as well the current trends and challenges on the regional and global level. An overview of relevant Black Sea Commission's observers and partners will be provided; existing and possible future arrangements with them will be further described and analyzed. Some concrete recommendations on the improvements in the management of marine living resources in the Black Sea basin will be proposed.

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