The location of the Black Sea
Map of the Black Sea with bathymetry and surrounding relief
|Primary inflows||Danube, Dnieper, Southern Bug, Dniester, Don, Kuban, Rioni, Kızılırmak|
|Basin countries|| Bulgaria, Romania, Ukraine, Russia, Georgia, Turkey |
A large number of countries included in drainage basins for inflow rivers
|Max. length||1,175 km (730 mi)|
|Surface area||436,402 km2 (168,500 sq mi)|
|Average depth||1,253 m (4,111 ft)|
|Max. depth||2,600 m (8,530 ft)|
|Water volume||547,000 km3 (131,200 cu mi)|
The Black Sea is a body of water and marginal sea of the Atlantic Ocean between Eastern Europe, the Caucasus, and Western Asia.It is supplied by a number of major rivers, such as the Danube, Dnieper, Southern Bug, Dniester, Don, and the Rioni. The watersheds of many countries drain into the Black Sea beyond the six that immediately border it.
The Black Sea has an area of 436,400 km2 (168,500 sq mi) (not including the Sea of Azov), a maximum depth of 2,212 m (7,257 ft), and a volume of 547,000 km3 (131,000 cu mi). It is constrained by the Pontic Mountains to the south, Caucasus Mountains to the east, Crimean Mountains to the north, Strandzha to the southwest, Balkan Mountains to the west, Dobrogea Plateau to the northwest, and features a wide shelf to the northwest.
The longest east–west extent is about 1,175 km (730 mi). Important cities along the coast include Odessa, Sevastopol, Samsun, and Istanbul.
The Black Sea is bordered by Ukraine, Romania, Bulgaria, Turkey, Georgia, and Russia. It has a positive water balance with an annual net outflow of 300 km3 (72 cu mi) per year through the Bosporus and the Dardanelles into the Aegean Sea.[ citation needed ] While the net flow of water through the Bosporus and Dardanelles (known collectively as the Turkish Straits) is out of the Black Sea, generally water is flowing in both directions simultaneously. Denser, more saline water from the Aegean flows into the Black Sea underneath the less dense, fresher outflowing water from the Black Sea. This creates a significant and permanent layer of deep water which does not drain or mix and is therefor anoxic. This anoxic layer is responsible for the preservation of ancient shipwrecks which have been found in the Black sea.
The Black Sea ultimately drains into the Mediterranean Sea, via the Turkish Straits and the Aegean Sea. The Bosporus Strait connects it to the small Sea of Marmara which in turn is connected to the Aegean Sea via the Strait of the Dardanelles. To the north the Black Sea is connected to the Sea of Azov by the Kerch Strait.
The water level has varied significantly over geological time. Due to these variations in the water level in the basin, the surrounding shelf and associated aprons have sometimes been dry land. At certain critical water levels, connections with surrounding water bodies can become established. It is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the world ocean. During geological periods when this hydrological link was not present, the Black Sea was an endorheic basin, operating independently of the global ocean system (similar to the Caspian Sea today). Currently, the Black Sea water level is relatively high; thus, water is being exchanged with the Mediterranean. The Turkish Straits connect the Black Sea with the Aegean Sea and comprise the Bosporus, the Sea of Marmara, and the Dardanelles. The Black Sea undersea river is a current of particularly saline water flowing through the Bosporus Strait and along the seabed of the Black Sea. The discovery of the river announced on August 1, 2010, was made by scientists at the University of Leeds and is the first of its kind in the world.The undersea river stems from salty water spilling through the Bosporus Strait from the Mediterranean Sea into the Black Sea, where the water has a lower salt content.
The International Hydrographic Organization defines the limits of the Black Sea as follows:
On the Southwest. The Northeastern limit of the Sea of Marmara [A line joining Cape Rumili with Cape Anatoli (41°13'N)]. In the Kertch Strait. A line joining Cape Takil and Cape Panaghia (45°02'N).
|6||Sevastopol||Russia (de facto)/Ukraine (de jure)||national-level municipality on the Crimean Peninsula||379,200|
Current names of the sea are usually equivalents of the English name "Black Sea", including these given in the countries bordering the sea:
Such names have not yet been shown conclusively to predate the 13th century.
In Greece, the historical name "Euxine Sea" holds a different meaning (see below), is still widely used:
The principal Greek name "Póntos Áxeinos" is generally accepted to be a rendering of Iranian word *axšaina- ("dark colored"), compare Avestan axšaēna- ("dark colored"), Old Persian axšaina- (color of turquoise), Middle Persian axšēn/xašēn ("blue"), and New Persian xašīn ("blue"), as well as Ossetic œxsīn ("dark gray"). The ancient Greeks, most likely those living to the north of the Black Sea, subsequently adopted the name and altered it to á-xe(i)nos. Thereafter, Greek tradition refers to the Black Sea as the "Inhospitable Sea", Πόντος ἌξεινοςPóntos Áxeinos, which is first attested in Pindar (c. 475 BC). The name was considered to be "ominous" and was later changed into the euphemistic name "Hospitable sea", Εὔξεινος ΠόντοςEúxeinos Póntos, which was also for the first time attested in Pindar. This became the commonly used designation for the sea in Greek. In contexts related to mythology, the older form Póntos Áxeinos remained favored.
It has been erroneously suggested that the name was derived from the color of the water, or was at least related to climatic conditions. 484–c. 425 BC) in fact designated the Indian Ocean, together with bodies of water now known as the Persian Gulf and the Red Sea. According to the same explanation and reasoning, it is therefore considered to be impossible for the Scythians, who principally roamed in present-day Ukraine and Russia, to have given the designation because they lived to the north of the sea, which would, therefore, be a southern body of water for them. The name could have only been given by people who were aware of both the northern "black/dark" and southern "red" seas; it is therefore considered probable it was given its name by the Achaemenids (550–330 BC).Black or dark in this context, however, referred to a system in which colors represent the cardinal points of the known world. Black or dark represented the north; red the south; white the west; and green or light blue for the east. The symbolism based on cardinal points was used on multiple occasions and is therefore widely attested. For example, the "Red Sea", a body of water reported since the time of Herodotus (c.
Strabo's Geographica (1.2.10) reports that in antiquity, the Black Sea was often simply called "the Sea" (ὁ πόντοςho Pontos). He also thought the Black Sea was called "inhospitable" before Greek colonization because it was difficult to navigate and because its shores were inhabited by savage tribes. (7.3.6) The name was changed to "hospitable" after the Milesians had colonized the Pontus region of the southern shoreline, making it part of Greek civilization.
In Greater Bundahishn, a sacred Zoroastrian text written in Middle Persian, the Black Sea is called Siyābun. [ citation needed ]A 1570 map of Asia titled Asiae Nova Descriptio from Abraham Ortelius's Theatrum Orbis Terrarum labels the sea Mar Maggior ("Great Sea", compare Latin mare major).
English-language writers of the 18th century often used the name Euxine Sea ( // or // ) to refer to the Black Sea. Edward Gibbon, for instance, calls the sea by this name throughout The History of the Decline and Fall of the Roman Empire . During the Ottoman Empire period, the Black Sea was called either Bahr-e Siyah or Karadeniz, both meaning "the Black Sea" in Ottoman Turkish.[ citation needed ]
In the tenth-century geography book Hudud al-'Alam , which was written in Persian by an unknown author, the Black Sea is called Georgian Sea, Sea of Georgians (daryā-yi Gurz). ზღუა სპერისა), which means the "Sea of Speri", named after the Kartvelian tribe Speris or Saspers. The modern names of the Black Sea (Chyornoye more, Karadeniz, etc.), originated in the 13th century.The Georgian Chronicles used the name zğua sperisa (
The Black Sea is divided into two depositional basins—the Western Black Sea and Eastern Black Sea—separated by the Mid-Black Sea High, which includes the Andrusov Ridge, Tetyaev High, and Archangelsky High, extending south from the Crimean Peninsula. The basin includes two distinct relict back-arc basins which were initiated by the splitting of an Albian volcanic arc and the subduction of both the Paleo- and Neo-Tethys Oceans, but the timings of these events remain uncertain. Arc volcanism and extension occurred as the Neo-Tethys Ocean subducted under the southern margin of Laurasia during the Mesozoic. Uplift and compressional deformation took place as the Neotethys continued to close. Seismic surveys indicate that rifting began in the Western Black Sea in the Barremian and Aptian followed by the formation of oceanic crust 20 million years later in the Santonian.Since its initiation, compressional tectonic environments led to subsidence in the basin, interspersed with extensional phases resulting in large-scale volcanism and numerous orogenies, causing the uplift of the Greater Caucasus, Pontides, Southern Crimean Peninsula and Balkanides mountain ranges.
During the Messinian salinity crisis in the neighboring Mediterranean Sea, water levels fell but without drying up the sea.
The ongoing collision between the Eurasian and African plates and westward escape of the Anatolian block along the North Anatolian Fault and East Anatolian Faults dictates the current tectonic regime,which features enhanced subsidence in the Black Sea basin and significant volcanic activity in the Anatolian region. These geological mechanisms, in the long term, have caused the periodic isolations of the Black Sea from the rest of the global ocean system.
The large shelf to the north of the basin is up to 190 km (120 mi) wide and features a shallow apron with gradients between 1:40 and 1:1000. The southern edge around Turkey and the eastern edge around Georgia, however, are typified by a narrow shelf that rarely exceeds 20 km (12 mi) in width and a steep apron that is typically 1:40 gradient with numerous submarine canyons and channel extensions. The Euxine abyssal plain in the centre of the Black Sea reaches a maximum depth of 2,212 metres (7,257.22 feet) just south of Yalta on the Crimean Peninsula.
The littoral zone of the Black Sea is often referred to as the Pontic littoral or Pontic zone.
The area surrounding the Black Sea is commonly referred to as the Black Sea Region. Its northern part lies within the Chernozem belt (black soil belt) which goes from eastern Croatia (Slavonia), along the Danube (northern Serbia, northern Bulgaria (Danubian Plain) and southern Romania (Wallachian Plain)) to northeast Ukraine and further across the Central Black Earth Region and southern Russia into Siberia.
The Black Sea contains oil and natural gas resources but exploration in the sea is incomplete. As of 2017, 20 wells are in place. Throughout much of its existence, the Black Sea has had significant oil and gas-forming potential because of significant inflows of sediment and nutrient-rich waters. However, this varies geographically. For example, prospects are poorer off the coast of Bulgaria because of the large influx of sediment from the Danube River which obscured sunlight and diluted organic-rich sediments. Many of the discoveries to date have taken place offshore of Romania in the Western Black Sea and only a few discoveries have been made in the Eastern Black Sea.
During the Eocene, the Paratethys Ocean was partially isolated and sea levels fell. During this time sand shed off the rising Balkanide, Pontide and Caucasus mountains trapped organic material in the Maykop Suite of rocks through the Oligocene and early Miocene. Natural gas appears in rocks deposited in the Miocene and Pliocene by the paleo-Dnieper and pale-Dniester rivers, or in deep-water Oligocene-age rocks. Serious exploration began in 1999 with two deep-water wells, Limanköy-1 and Limanköy-2, drilled in Turkish waters. Next, the HPX (Hopa)-1 deepwater well targeted late Miocene sandstone units in Achara-Trialet fold belt (also known as the Gurian fold belt) along the Georgia-Turkey maritime border. Although geologists inferred that these rocks might have hydrocarbons that migrated from the Maykop Suite, the well was unsuccessful. No more drilling happened for five years after the HPX-1 well. Then in 2010, Sinop-1 targeted carbonate reservoirs potentially charged from the nearby Maykop Suite on the Andrusov Ridge, but the well-struck only Cretaceous volcanic rocks. Yassihöyük-1 encountered similar problems. Other Turkish wells, Sürmene-1 and Sile-1 drilled in the Eastern Black Sea in 2011 and 2015 respectively tested four-way closures above Cretaceous volcanoes, with no results in either case. A different Turkish well, Kastamonu-1 drilled in 2011 did successfully find thermogenic gas in Pliocene and Miocene shale-cored anticlines in the Western Black Sea. A year later in 2012, Romania drilled Domino-1 which struck gas prompting the drilling of other wells in the Neptun Deep. In 2016, the Bulgarian well Polshkov-1 targeted Maykop Suite sandstones in the Polshkov High and Russia is in the process of drilling Jurassic carbonates on the Shatsky Ridge as of 2018.
The Black Sea is a marginal seaand is the world's largest body of water with a meromictic basin. The deep waters do not mix with the upper layers of water that receive oxygen from the atmosphere. As a result, over 90% of the deeper Black Sea volume is anoxic water. The Black Sea's circulation patterns are primarily controlled by basin topography and fluvial inputs, which result in a strongly stratified vertical structure. Because of the extreme stratification, it is classified as a salt wedge estuary.
The Black Sea only experiences water transfer with the Mediterranean Sea, so all inflow and outflow occurs in the Bosporus and Dardanelles. Inflow from the Mediterranean has a higher salinity and density than the outflow, creating the classical estuarine circulation. This means that the inflow of dense water from the Mediterranean occurs at the bottom of the basin while the outflow of fresher Black Sea surface-water into the Marmara Sea occurs near the surface. The outflow is 16 000 m3/s (around 500 km3/year) and the inflow is 11 000 m3/s (around 350 km3/year), acc to Gregg (2002).
The following water budget can be estimated:
The southern sill of the Bosporus is located at -36.5 m below present sea level (deepest spot of the shallowest cross-section in the Bosporus, located in front of Dolmabahçe Palace) and has a wet section of around 38 000 m2. m/s, but much higher speeds are found locally, inducing significant turbulence and vertical shear. This allows for turbulent mixing of the two layers. Surface water leaves the Black Sea with a salinity of 17 psu and reaches the Mediterranean with a salinity of 34 PSU. Likewise, an inflow of the Mediterranean with salinity 38.5 PSU experiences a decrease to about 34 psu.Inflow and outflow current speeds are averaged around 0.3 to 0.4
Mean surface circulation is cyclonic and waters around the perimeter of the Black Sea circulate in a basin-wide shelfbreak gyre known as the Rim Current. The Rim Current has a maximum velocity of about 50–100 cm/s. Within this feature, two smaller cyclonic gyres operate, occupying the eastern and western sectors of the basin. The Eastern and Western Gyres are well-organized systems in the winter but dissipate into a series of interconnected eddies in the summer and autumn. Mesoscale activity in the peripheral flow becomes more pronounced during these warmer seasons and is subject to interannual variability.
Outside of the Rim Current, numerous quasi-permanent coastal eddies are formed as a result of upwelling around the coastal apron and "wind curl" mechanisms. The intra-annual strength of these features is controlled by seasonal atmospheric and fluvial variations. During the spring, the Batumi eddy forms in the southeastern corner of the sea.
Beneath the surface waters—from about 50–100 meters—there exists a halocline that stops at the Cold Intermediate Layer (CIL). This layer is composed of cool, salty surface waters, which are the result of localized atmospheric cooling and decreased fluvial input during the winter months. It is the remnant of the winter surface mixed layer. 100–200 metres (330–660 ft) and this density disparity is the major mechanism for isolation of the deep water.The base of the CIL is marked by a major pycnocline at about
Below the pycnocline is the Deep Water mass, where salinity increases to 22.3 PSU and temperatures rise to around 8.9 °C. The hydrochemical environment shifts from oxygenated to anoxic, as bacterial decomposition of sunken biomass utilizes all of the free oxygen. Weak geothermal heating and long residence time create a very thick convective bottom layer.
Because of the anoxic water at depth, organic matter, including anthropogenic artifacts such as boat hulls, are well preserved. During periods of high surface productivity, short-lived algal blooms form organic rich layers known as sapropels. Scientists have reported an annual phytoplankton bloom that can be seen in many NASA images of the region.As a result of these characteristics the Black Sea has gained interest from the field of marine archaeology as ancient shipwrecks in excellent states of preservation have been discovered, such as the Byzantine wreck Sinop D, located in the anoxic layer off the coast of Sinop, Turkey.
Modelling shows the release of the hydrogen sulfide clouds in the event of an asteroid impact into the Black Sea would pose a threat to health—or even life—for people living on the Black Sea coast.
There have been isolated reports of flares on the Black Sea occurring during thunderstorms, possibly caused by lightning igniting combustible gas seeping up from the sea depths.
The Black Sea supports an active and dynamic marine ecosystem, dominated by species suited to the brackish, nutrient-rich, conditions. As with all marine food webs, the Black Sea features a range of trophic groups, with autotrophic algae, including diatoms and dinoflagellates, acting as primary producers. The fluvial systems draining Eurasia and central Europe introduce large volumes of sediment and dissolved nutrients into the Black Sea, but the distribution of these nutrients is controlled by the degree of physiochemical stratification, which is, in turn, dictated by seasonal physiographic development.
During winter, strong wind promotes convective overturning and upwelling of nutrients, while high summer temperatures result in a marked vertical stratification and a warm, shallow mixed layer.Day length and insolation intensity also controls the extent of the photic zone. Subsurface productivity is limited by nutrient availability, as the anoxic bottom waters act as a sink for reduced nitrate, in the form of ammonia. The benthic zone also plays an important role in Black Sea nutrient cycling, as chemosynthetic organisms and anoxic geochemical pathways recycle nutrients which can be upwelled to the photic zone, enhancing productivity.
In total, Black Sea's biodiversity contains around one-third of Mediterranean's and is experiencing natural and artificial invasions or Mediterranizations.
The main phytoplankton groups present in the Black Sea are dinoflagellates, diatoms, coccolithophores and cyanobacteria. Generally, the annual cycle of phytoplankton development comprises significant diatom and dinoflagellate-dominated spring production, followed by a weaker mixed assemblage of community development below the seasonal thermocline during summer months and surface-intensified autumn production.This pattern of productivity is also augmented by an Emiliania huxleyi bloom during the late spring and summer months.
Since the 1960s, rapid industrial expansion along the Black Sea coast line and the construction of a major dam has significantly increased annual variability in the N:P:Si ratio in the basin. In coastal areas, the biological effect of these changes has been an increase in the frequency of monospecific phytoplankton blooms, with diatom bloom frequency increasing by a factor of 2.5 and non-diatom bloom frequency increasing by a factor of 6. The non-diatoms, such as the prymnesiophytes Emiliania huxleyi (coccolithophore), Chromulina sp., and the Euglenophyte Eutreptia lanowii are able to out-compete diatom species because of the limited availability of Si, a necessary constituent of diatom frustules.As a consequence of these blooms, benthic macrophyte populations were deprived of light, while anoxia caused mass mortality in marine animals.
The decline in macrophytes was further compounded by overfishing during the 1970s, while the invasive ctenophore Mnemiopsis reduced the biomass of copepods and other zooplankton in the late 1980s. Additionally, an alien species—the warty comb jelly (Mnemiopsis leidyi)—was able to establish itself in the basin, exploding from a few individuals to estimated biomass of one billion metric tons.The change in species composition in Black Sea waters also has consequences for hydrochemistry, as Ca-producing coccolithophores influence salinity and pH, although these ramifications have yet to be fully quantified. In central Black Sea waters, Si levels were also significantly reduced, due to a decrease in the flux of Si associated with advection across isopycnal surfaces. This phenomenon demonstrates the potential for localized alterations in Black Sea nutrient input to have basin-wide effects.
Pollution reduction and regulation efforts have led to a partial recovery of the Black Sea ecosystem during the 1990s, and an EU monitoring exercise, 'EROS21', revealed decreased N and P values, relative to the 1989 peak.Recently, scientists have noted signs of ecological recovery, in part due to the construction of new sewage treatment plants in Slovakia, Hungary, Romania, and Bulgaria in connection with membership in the European Union. Mnemiopsis leidyi populations have been checked with the arrival of another alien species which feeds on them.
In the past, the range of the Asiatic lion extended from South Asia to the Balkans, possibly up to the Danube. Places like Turkey and the Trans-Caucasus were in this range. The Caspian tiger occurred in eastern Turkey and the Caucasus, at least. The lyuti zver (Old East Slavic for "fierce animal") that was encountered by Vladimir II Monomakh, Velikiy Kniaz of Kievan Rus' (which ranged to the Black Sea in the south),may have been a tiger or leopard, rather than a wolf or lynx, due to the way it behaved towards him and his horse.
Short-term climatic variation in the Black Sea region is significantly influenced by the operation of the North Atlantic oscillation, the climatic mechanisms resulting from the interaction between the north Atlantic and mid-latitude air masses.While the exact mechanisms causing the North Atlantic Oscillation remain unclear, it is thought the climate conditions established in western Europe mediate the heat and precipitation fluxes reaching Central Europe and Eurasia, regulating the formation of winter cyclones, which are largely responsible for regional precipitation inputs and influence Mediterranean Sea Surface Temperatures (SST's).
The relative strength of these systems also limits the amount of cold air arriving from northern regions during winter.Other influencing factors include the regional topography, as depressions and storms systems arriving from the Mediterranean are funneled through the low land around the Bosporus, Pontic and Caucasus mountain ranges acting as waveguides, limiting the speed and paths of cyclones passing through the region.
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Some islands in the Black sea belong to Bulgaria, Romania, Turkey, and Ukraine:
The Black Sea is connected to the World Ocean by a chain of two shallow straits, the Dardanelles and the Bosporus. The Dardanelles is 55 m (180 ft) deep and the Bosporus is as shallow as 36 m (118 ft). By comparison, at the height of the last ice age, sea levels were more than 100 m (330 ft) lower than they are now.
There is also evidence that water levels in the Black Sea were considerably lower at some point during the post-glacial period. Some researchers theorize that the Black Sea had been a landlocked freshwater lake (at least in upper layers) during the last glaciation and for some time after.
In the aftermath of the last glacial period, water levels in the Black Sea and the Aegean Sea rose independently until they were high enough to exchange water. The exact timeline of this development is still subject to debate. One possibility is that the Black Sea filled first, with excess freshwater flowing over the Bosporus sill and eventually into the Mediterranean Sea. There are also catastrophic scenarios, such as the "Black Sea deluge theory" put forward by William Ryan, Walter Pitman and Petko Dimitrov.
The Black Sea deluge is a hypothesized catastrophic rise in the level of the Black Sea circa 5600 BC due to waters from the Mediterranean Sea breaching a sill in the Bosporus Strait. The hypothesis was headlined when The New York Times published it in December 1996, shortly before it was published in an academic journal.While it is agreed that the sequence of events described did occur, there is debate over the suddenness, dating, and magnitude of the events. Relevant to the hypothesis is that its description has led some to connect this catastrophe with prehistoric flood myths.
The Black Sea was a busy waterway on the crossroads of the ancient world: the Balkans to the west, the Eurasian steppes to the north, the Caucasus and Central Asia to the east, Asia Minor and Mesopotamia to the south, and Greece to the south-west.
The oldest processed gold in the world was found in Varna, Bulgaria, and Greek mythology portrays the Argonauts as sailing on the Black Sea. The land at the eastern end of the Black Sea, Colchis, (now Georgia), marked for the Greeks the edge of the known world.
The steppes to the north of the Black Sea have been suggested as the original homeland ( Urheimat ) of the speakers of the Proto-Indo-European language, (PIE) the progenitor of the Indo-European language family, by some scholars such as Marija Gimbutas; others move the homeland further east towards the Caspian Sea, yet others to Anatolia.
Greek presence in the Black Sea began at least as early as the 9th century BC with colonization the Black Sea's southern coast. By 500 BC, permanent Greek communities existed all around the Black Sea and a lucrative trade network connected the entirety of the Black Sea to the wider Mediterranean. While Greek colonies generally maintained very close cultural ties to their founding polis, Greek colonies in the Black Sea began to develop their own Black Sea Greek culture, know today as Pontic. The coastal community of Black Sea Greeks remained a prominent part of the Greek World for centuries.
The Black Sea became a virtual Ottoman Navy lake within five years of Genoa losing the Crimean Peninsula in 1479, after which the only Western merchant vessels to sail its waters were those of Venice's old rival Ragusa. This restriction was challenged by the Russian Navy from 1783 until the relaxation of export controls in 1789 because of the French Revolution.
The Black Sea was a significant naval theatre of World War I and saw both naval and land battles during World War II.
Ancient trade routes in the region are currently[ when? ] being extensively studied by scientists, as the Black Sea was sailed by Hittites, Carians, Colchians, Thracians, Greeks, Persians, Cimmerians, Scythians, Romans, Byzantines, Goths, Huns, Avars, Slavs, Varangians, Crusaders, Venetians, Genoese, Georgians, Tatars and Ottomans.
Perhaps the most promising areas in deepwater archaeology are the quest for submerged prehistoric settlements in the continental shelf and for ancient shipwrecks in the anoxic zone, which are expected to be exceptionally well preserved due to the absence of oxygen. This concentration of historical powers, combined with the preservative qualities of the deep anoxic waters of the Black Sea, has attracted increased interest from marine archaeologists who have begun to discover a large number of ancient ships and organic remains in a high state of preservation.
According to NATO, the Black sea is a strategic corridor that provides smuggling channels for moving legal and illegal goods including drugs, radioactive materials, and counterfeit goods that can be used to finance terrorism.
According to the International Transport Workers' Federation 2013 study, there were at least 30 operating merchant seaports in the Black Sea (including at least 12 in Ukraine).
According to the International Transport Workers' Federation 2013 study, there were around 2,400 commercial vessels operating in the Black Sea.
Anchovy: the Turkish commercial fishing fleet catches around 300,000 tons per year on average, and fishery carried out mainly in winter and the highest portion of the stock is caught between November and December.
Since the 1980s, the Soviet Union started offshore drilling for petroleum in the sea's western portion (adjoining Ukraine's coast). Independent Ukraine continued and intensified that effort within its exclusive economic zone, inviting major international oil companies for exploration. Discovery of the new, massive oilfields in the area stimulated an influx of foreign investments. It also provoked a short-term peaceful territorial dispute with Romania which was resolved in 2011 by an international court redefining the exclusive economic zones between the two countries.
In the years following the end of the Cold War, the popularity of the Black Sea as a tourist destination steadily increased. Tourism at Black Sea resorts became one of the region's growth industries.The following is a list of notable Black Sea resort towns:
The 1936 Montreux Convention provides for free passage of civilian ships between the international waters of the Black and the Mediterranean Seas. However, a single country (Turkey) has complete control over the straits connecting the two seas. Military ships are separate categories from civilian ships and they can only pass through the straits if the ship is belonging to a Black Seapower. Other military ships have the right to pass through the straits if they are not in a war against Turkey and they can stay in the Black Sea basin for a limited time. The 1982 amendments to the Montreux Convention allow Turkey to close the Straits at its discretion in both wartime and peacetime.
The 1936 Montreux Convention governs the passage of vessels between the Black, the Mediterranean and Aegean Seas and the presence of military vessels belonging to non-littoral states in the Black Sea waters.
In December 2018, the Kerch Strait incident took place. The Russian Navy and Coast guard took control of three ships belonging to their counterparts. The ships were trying to enter the Black Sea
The Bosporus or Bosphorus is a narrow, natural strait and an internationally significant waterway located in northwestern Turkey. It forms part of the continental boundary between Europe and Asia, and divides Turkey by separating Anatolia from Thrace. It is the world's narrowest strait used for international navigation. The Bosporus connects the Black Sea with the Sea of Marmara, and, by extension via the Dardanelles, the Aegean and Mediterranean seas.
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Southern Europe and Anatolia, on the south by North Africa and on the east by the Levant. Although the sea is sometimes considered a part of the Atlantic Ocean, it is usually referred to as a separate body of water. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years before being refilled by the Zanclean flood about 5.3 million years ago.
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems, and is often recognized by the discoloration in the water from their pigments. The term algae encompasses many types of aquatic photosynthetic organisms, both macroscopic, multicellular organisms like seaweed and microscopic, unicellular organisms like cyanobacteria. Algal bloom commonly refers to rapid growth of microscopic, unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest.
A coccolithophore is a unicellular, eukaryotic phytoplankton (alga). They belong either to the kingdom Protista, according to Robert Whittaker's Five kingdom classification, or clade Hacrobia, according to the newer biological classification system. Within the Hacrobia, the coccolithophorids are in the phylum or division Haptophyta, class Prymnesiophyceae. Coccolithophorids are distinguished by special calcium carbonate plates of uncertain function called coccoliths, which are also important microfossils. However, there are Prymnesiophyceae species lacking coccoliths, so not every member of Prymnesiophyceae is coccolithophorid. Coccolithophores are almost exclusively marine and are found in large numbers throughout the sunlight zone of the ocean.
The Sea of Azov is a sea in Eastern Europe connected to the Black Sea by the narrow Strait of Kerch, and is sometimes regarded as a northern extension of the Black Sea. The sea is bounded in the northwest by Ukraine, in the southeast by Russia. The Don River and Kuban River are the major rivers that flow into it. There is a constant outflow of water from the Sea of Azov to the Black Sea.
The spring bloom is a strong increase in phytoplankton abundance that typically occurs in the early spring and lasts until late spring or early summer. This seasonal event is characteristic of temperate North Atlantic, sub-polar, and coastal waters. Phytoplankton blooms occur when growth exceeds losses, however there is no universally accepted definition of the magnitude of change or the threshold of abundance that constitutes a bloom. The magnitude, spatial extent and duration of a bloom depends on a variety of abiotic and biotic factors. Abiotic factors include light availability, nutrients, temperature, and physical processes that influence light availability, and biotic factors include grazing, viral lysis, and phytoplankton physiology. The factors that lead to bloom initiation are still actively debated.
The Black Sea deluge is the most well known of three hypothetical flood scenarios proposed for the Late Quaternary history of the Black Sea. It is one of the two of these flood scenarios which propose a rapid, even catastrophic, rise in sea level of the Black Sea during the Late Quaternary.
Emiliania huxleyi is a species of coccolithophore found in almost all ocean ecosystems from the equator to sub-polar regions, and from nutrient rich upwelling zones to nutrient poor oligotrophic waters. It is one of thousands of different photosynthetic plankton that freely drift in the euphotic zone of the ocean, forming the basis of virtually all marine food webs. It is studied for the extensive blooms it forms in nutrient-depleted waters after the reformation of the summer thermocline. Like other coccolithophores, E. huxleyi is a single-celled phytoplankton covered with uniquely ornamented calcite disks called coccoliths. Individual coccoliths are abundant in marine sediments although complete coccospheres are more unusual. In the case of E. huxleyi, not only the shell, but also the soft part of the organism may be recorded in sediments. It produces a group of chemical compounds that are very resistant to decomposition. These chemical compounds, known as alkenones, can be found in marine sediments long after other soft parts of the organisms have decomposed. Alkenones are most commonly used by earth scientists as a means to estimate past sea surface temperatures.
Oceanic anoxic events or anoxic events (anoxia conditions) were intervals in the Earth's past where portions of oceans became depleted in oxygen (O2) over a large geographic areas. During some of these events, euxinia, waters that contain hydrogen sulfide, H
2S, developed. Although anoxic events have not happened for millions of years, the geological record shows that they happened many times in the past. Anoxic events coincided with several mass extinctions and may have contributed to them. These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating. Many geologists believe oceanic anoxic events are strongly linked to slowing of ocean circulation, climatic warming, and elevated levels of greenhouse gases. Researchers have proposed enhanced volcanism (the release of CO2) as the "central external trigger for euxinia".
Noctiluca scintillans, commonly known as the sea sparkle, and also published as Noctiluca miliaris, is a free-living, marine-dwelling species of dinoflagellate that exhibits bioluminescence when disturbed. Its bioluminescence is produced throughout the cytoplasm of this single-celled protist, by a luciferin-luciferase reaction in thousands of spherically shaped organelles, called scintillons.
Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen and are a more severe condition of hypoxia. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre. This condition is generally found in areas that have restricted water exchange.
Sapropel is a term used in marine geology to describe dark-coloured sediments that are rich in organic matter. Sapropels events occurs periodically and are specific to the Mediterranean Sea. Organic carbon concentrations in sapropels commonly exceed 2% in weight.
Proterorhinus marmoratus is a species of gobiid fish, a tubenose goby native to the brackish water parts of the Black Sea and the Sea of Azov, near the coasts of Bulgaria, Georgia, Romania, Ukraine and Russia. Also it is found in the Marmora Sea (Turkey). It can reach a length of 11.5 centimetres (4.5 in) TL.
The genus Ceratium is restricted to a small number of freshwater dinoflagellate species. Previously the genus contained also a large number of marine dinoflagellate species. However, these marine species have now been assigned to a new genus called Tripos. Ceratium dinoflagellates are characterized by their armored plates, two flagella, and horns. They are found worldwide and are of concern due to their blooms.
Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica Si(O2), as opposed to calcareous oozes, which are made from skeletons of calcium carbonate organisms (i.e. coccolithophores). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes.
The deep chlorophyll maximum (DCM), also called the subsurface chlorophyll maximum, is the region below the surface of water with the maximum concentration of chlorophyll. A DCM is not always present - sometimes there is more chlorophyll at the surface than at any greater depth - but it is a common feature of most aquatic ecosystems, especially in regions of strong thermal stratification. The depth, thickness, intensity, composition, and persistence of DCMs vary widely. The DCM generally exists at the same depth as the nutricline, the region of the ocean where the greatest change in the nutrient concentration occurs with depth.
Marine microorganisms are defined by their habitat as the microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism is any microscopic living organism, that is, any life form too small for the naked human eye to really see, needing a microscope. Microorganisms are very diverse. They can be single-celled or multicellular and include all bacteria and archaea and most protozoa, as well as some species of fungi, algae, and certain microscopic animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify biologically active entities such as viruses and viroids as microorganisms, but others consider these as nonliving.
The Mediterranean horse mackerel, also known as the Black Sea horse mackerel, horse mackerel, Mediterranean scad, common scad, or simply scad, is a species of mackerel in the family Carangidae found in the eastern Atlantic from Bay of Biscay to Mauritania, including the Mediterranean Sea. It is a benthopelagic, subtropical, marine fish that can reach up to 60 cm (24 in) in length. In the countries near the Mediterranean and Black Seas, it makes up a significant portion of fish catch, 54% of fish caught in the latter. Despite overfishing in the 1980s, catch numbers have leveled out and it is listed as least concern by the International Union for the Conservation of Nature.
Euxinia or euxinic conditions occur when water is both anoxic and sulfidic. This means that there is no oxygen (O2) and a raised level of free hydrogen sulfide (H2S). Euxinic bodies of water are frequently strongly stratified, have an oxic, highly productive, thin surface layer, and have anoxic, sulfidic bottom water. The word euxinia is derived from the Greek name for the Black Sea (Εὔξεινος Πόντος (Euxeinos Pontos)) which translates to "hospitable sea". Euxinic deep water is a key component of the Canfield ocean, a model of oceans during the Proterozoic period (known as the Boring Billion) proposed by Donald Canfield, an American geologist, in 1998. There is still debate within the scientific community on both the duration and frequency of euxinic conditions in the ancient oceans. Euxinia is relatively rare in modern bodies of water, but does still happen in places like the Black Sea and certain fjords.
Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Protists are eukaryotes that cannot be classified as plants, fungi or animals. They are usually single-celled and microscopic. Life originated as single-celled prokaryotes and later evolved into more complex eukaryotes. Eukaryotes are the more developed life forms known as plants, animals, fungi and protists. The term protist came into use historically as a term of convenience for eukaryotes that cannot be strictly classified as plants, animals or fungi. They are not a part of modern cladistics, because they are paraphyletic.
black sea 1175 km east west.
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