Black Sea

The Enigma of the Black Sea: A Marginal Mediterranean Gem

Imagine a vast, mysterious sea nestled between Europe and Asia, a place where history whispers through its waters and secrets lie hidden beneath its surface. The Black Sea, with its intriguing name and complex geography, is more than just a body of water—it’s a living testament to the past and present.

The Black Sea: A Geographical Marvel

With an area of 436,400 km², the Black Sea is a marginal Mediterranean sea that stretches across borders like a ribbon. It’s bounded by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine, each contributing to its rich tapestry of cultures and histories.

The sea receives water from major rivers such as the Danube, Dnieper, and Dniester, creating a dynamic ecosystem that supports diverse life forms. The coast rises rapidly, forming majestic mountains like the Pontic Mountains to the south, the Caucasus Mountains to the east, and the Crimean Mountains to the north.

A Water Balance Act

The Black Sea has a positive water balance, with an annual net outflow of 300 km³ through the Bosporus and Dardanelles into the Aegean Sea. This creates a permanent layer of deep water that does not drain or mix, resulting in anoxic conditions that preserve ancient shipwrecks.

The sea’s water level has varied significantly over geological time, with connections to surrounding water bodies established at certain critical levels. It is currently connected to the Mediterranean through the Turkish Straits and has a relatively high water level, allowing for exchange of water with the Mediterranean.

Names and Legends

The Black Sea has multiple names in various languages, including ‘Black Sea,’ ‘Karadeniz’ in Turkish, and ‘Chorne more’ in Russian. The earliest known name is the ‘Sea of Zalpa.’ Ancient Greek voyagers named it Á-xe(i)nos, meaning inhospitable, due to its difficult navigation and hostile barbarian natives. The name was changed to Póntos Eúxeinos, or Hospitable Sea, after the Milesians colonised the region.

The name ‘Black Sea’ is derived from a system of colour symbolism representing cardinal directions, with black for north. The sea has been known by various names throughout history, including Siyābun in the Middle Persian Zoroastrian scripture, Georgian Sea in the 10th-century Persian geography book Hudud al-‘Alam, and Chyornoye more during the 13th century.

Geography and Drainage

The Black Sea’s geography includes a littoral zone known as the Pontic littoral or Pontic zone. The largest bays are Karkinit Bay in Ukraine; Gulf of Burgas in Bulgaria; Dnieprovski Bay and Dniestrovski Bay in Ukraine; Sinop Bay and Samsun Bay in Turkey.

The largest rivers flowing into the Black Sea are the Danube River, Don River, and Dniester River. The drainage basin covers 77 million sq mi across 24 countries, with islands belonging to Bulgaria, Romania, Turkey, and Ukraine.

Climate and Geology

The climate of the Black Sea is influenced by the North Atlantic Oscillation, regional topography, and Mediterranean sea surface temperatures. The geology and bathymetry include two depositional basins: the Western Black Sea and Eastern Black Sea, with distinct relict back-arc basins.

The basin formed due to splitting of a volcanic arc, subduction of oceans, and tectonic environments. The Messinian salinity crisis led to periodic isolations from the global ocean system. The large shelf has shallow gradients, narrow shelves around Turkey and Georgia, and steep apron with submarine canyons.

The Euxine abyssal plain reaches a maximum depth of 2,212 meters. Chronostratigraphy includes Paleo-Euxinian, Karangat marine transgression, Neoeuxinian transgression, and Khvalinian transgression. Neoeuxinian deposits found below -20 m water depth in three layers on the shelf.

Circulation Patterns

The Black Sea’s circulation patterns are controlled by basin topography and fluvial inputs, resulting in a strongly stratified vertical structure. The estuarine circulation is driven by the difference in salinity and density between the Mediterranean inflow and outflow, with denser water flowing from the bottom to the surface.

Water enters through the Bosporus and Dardanelles at 16,000 cubic meters per second and leaves through the same route at 500 cubic meters per second. The water budget of the sea is estimated to be 900 km³/a with an inflow of 350 km³/a via the Bosporus and outflow of 500 km³/a.

Undersea River and Anoxic Conditions

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 this river was made by scientists at the University of Leeds in 2010, which is the first of its kind to be identified.

Because of the anoxic water at depth, organic matter, including anthropogenic artifacts, 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.

Marine Ecosystem and Phytoplankton

The Black Sea supports an active and dynamic marine ecosystem, dominated by species suited to the brackish, nutrient-rich conditions. The main phytoplankton groups present are dinoflagellates, diatoms, coccolithophores, and cyanobacteria.

Dinoflagellates dominate the surface waters due to high organic matter content, while diatoms are present in colonies and exhibit a ‘boom and bust’ life cycle. Coccolithophores are motile autotrophic phytoplankton that produce calcium carbonate plates. Cyanobacteria are widely distributed throughout the Black Sea.

Historical Significance

The Black Sea has been sailed by various historical powers, including Hittites, Carians, Colchians, and Romans. The concentration of these powers, combined with the preservative qualities of deep anoxic waters, has attracted interest from marine archaeologists who have discovered ancient ships and organic remains in high preservation.

Greek presence in the Black Sea began at least as early as the 9th century BC, with permanent communities existing by 500 BC. The Black Sea became a lucrative trade-network connected to the Mediterranean, with Greek colonies developing their own Black Sea Greek culture known as Pontic.

Modern Challenges and Opportunities

The construction of dams and industrial expansion have disrupted the natural balance of nutrients in the Black Sea, causing monospecific phytoplankton blooms and mass mortality in marine animals. Pollution has been reduced through regulation efforts, leading to a partial recovery of the ecosystem.

One possibility is that the Black Sea filled first, with excess freshwater flowing over the Bosporus sill and eventually into the Mediterranean Sea. The Black Sea deluge hypothesis proposes a catastrophic rise in the level of the Black Sea around 5600 BC due to waters from the Mediterranean breaching a sill in the Bosporus Strait.

Modern Uses and Controversies

The popularity of the Black Sea as a tourist destination increased after the Cold War. Notable resort towns include Turkish resorts such as Limonlu, Kusadasi, and Bodrum. The Montreux Convention governs passage between the Black, Mediterranean, and Aegean seas, with Turkey controlling the straits.

The Russian Black Sea Fleet has its headquarters in Sevastopol. In 1941, the Soviet hospital ship Armenia was sunk by German aircraft while evacuating civilians and wounded soldiers from Crimea. The Kerch Strait incident occurred in December 2018, where Russia took control of three Ukrainian vessels.

During the Russian invasion of Ukraine in April 2022, the Russian cruiser Moskva was sunk in the western Black Sea by sea-skimming Neptune missiles. Russia announced plans to build a naval base on the Black Sea coast of Abkhazia in late 2023.

The Black Sea remains a fascinating and complex body of water, filled with mysteries waiting to be uncovered. From its historical significance to its modern challenges, the sea continues to captivate us with its stories and secrets. As we navigate through its depths, let’s remember that every drop holds a piece of history, a story waiting to be told.