Caspian Sea

Caspian Sea, Xəzər dənizi, دریای خزر or دریای مازندران, Russian: Каспийское море, Kazakh: Каспий теңізі, Chechen: Paama Xord, Turkmen: Hazar deňzi) is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of 371,000 km2 (143,200 sq mi) (not including Garabogazköl Aylagy) and a volume of 78,200 km3 (18,800 cu mi). It is in an endorheic basin (it has no outflows) and is bounded to the north by Russia, to the south by Iran, western Azerbaijan, and eastern Kazakhstan and Turkmenistan.

The ancient inhabitants of its littoral perceived the Caspian Sea as an ocean, probably because of its saltiness and seeming boundlessness. It has a salinity of approximately 1.2%, about a third the salinity of most seawater. The Caspian Sea has been called Gilan (جیلان or بحر جیلان) on ancient maps. In Iran, it is referred to as Daryâ-ye Mazandaran (دریای مازندران), meaning "the Sea of Mazandaran" in Persian, and sometimes also as Daryâ-ye Khazar.

History

The 17th-century cossak rebel and pirate Stenka Razin, on a raid in the Caspian (Vasily Surikov, 1906).

The earliest human remains around Caspian are from Dmanisi dating back to around 1.8 ma and yielded a number of skeletal remains of Homo erectus or ergaster. More later evidence for human occupation of the region come from a number of caves in Georgia and Azerbaijan such as Kudaro and Azykh Caves. There new evidence for Lower Paleolithic human occupation at south of Caspian from western Alburz. These are Ganj Par and Darband Cave sites. Neanderthal remains also have discovered at a cave site in Georgia. Discoveries in the Huto cave and the adjacent Kamarband cave, near the town of Behshahr, Mazandaran south of the Caspian in Iran, suggest human habitation of the area as early as 11,000 years ago.

Etymology

The word Caspian is derived from the name of the Caspi (Persian: کاسپی), an ancient people that lived to the south west of the sea in Transcaucasia. Strabo wrote that "to the country of the Albanians belongs also the territory called Caspiane, which was named after the Caspian tribe, as was also the sea; but the tribe has now disappeared". Moreover, the Caspian Gates, which is the name of a region in Tehran province of Iran, is another possible piece of evidence that they migrated to the south of the sea. There is a city named Qazvin in Iran which was a former capital of the Persian Empire.

According to Indian Hindu belief, the name 'Caspian' is supposed to have been derived from the Sanskrit word 'Kashyapa' the name of an ancient Indian Sage.

In classical antiquity among Greeks and Persians it was called the Hyrcanian Ocean. In Persian antiquity, as well as in modern Iran, it is known as the mazandaran sea (Persian: مازندران). Among Indians it was called Kashyap Sagar. In Turkic speaking countries it is known as the Khazar Sea. Old Russian sources call it the Khvalyn (Khvalynian) Sea (Хвалынское море /Хвалисское море) after the Khvalis, inhabitants of Khwarezmia. Ancient Arabic sources refer to as Baḥr Gilan (Arabic: بحر جیلان‎ - the Caspian/Gilan Sea).

Turkic languages use a consistent nomenclature that is different from the Indo-European languages above. For instance, in Turkmen, the name is Hazar deňzi, in Azeri, it's Xəzər dənizi, and in modern Turkish, it's Hazar denizi. In all these cases, the second word simply means "sea", and the first word refers to the historical Khazars who had a large empire based to the North of the Caspian Sea between the 7th and 10th centuries.

Geological history

Like the Black Sea, the Caspian Sea is a remnant of the ancient Paratethys Sea. The Caspian Sea became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. During warm and dry climatic periods, the landlocked sea has all but dried up, depositing evaporitic sediments like halite that have become covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. Due to the current inflow of fresh water, the Caspian Sea is a freshwater lake in its northern portions. It is more saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of the Earth's oceans. The Garabogazköl embayment, which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10.

Geography

Caspian Sea is the largest inland body of water in the world and accounts for 40 to 44 percent of the total lacustrine waters of the world. The coastlines of the Caspian are shared by Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The Caspian is divided into three distinct physical regions: the Northern, Middle, and Southern Caspian. The North-Middle boundary is the Mangyshlak Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle-South boundary is the Apsheron Threshold, a sill of tectonic origin between the Eurasian continent and an oceanic remnant, that runs through Zhiloi Island and Cape Kuuli. The Garabogazköl bay is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to the isthmus which cuts it off from the Caspian.

Divisions between the three regions are dramatic. The Northern Caspian only includes the Caspian shelf, and is very shallow; it accounts for less than one percent of the total water volume with an average depth of only 5–6 metres (16–20 ft). The sea noticeably drops off towards the Middle Caspian, where the average depth is 190 metres (620 ft). The Southern Caspian is the deepest, with oceanic depths of over 1,000 metres (3,300 ft). The Middle and Southern Caspian account for 33 percent and 66 percent of the total water volume, respectively. The northern portion of the Caspian Sea typically freezes in the winter, and in the coldest winters, ice will form in the south.

Fauna

The Caspian Sea holds great numbers of sturgeon, which yield eggs that are processed into caviar. Overfishing has depleted a number of the historic fisheries including the economic exhaustion of the tuna fishery. In recent years overfishing has threatened the sturgeon population to the point that environmentalists advocate banning sturgeon fishing completely until the population recovers. However, the high price of sturgeon caviar allows fisherman to afford bribes to ensure the authorities look the other way, making regulations in many locations ineffective. Caviar harvesting further endangers the fish stocks, since it targets reproductive females. The Caspian Sea along with the Black Sea is also home to the native Zebra mussel, which has been accidentally introduced and become an invasive species in many countries. The native range of the Common Carp extends to the Caspian Sea as well as the Black Sea and Aral Sea. Like the Zebra mussel it also has become an invasive species where it has been introduced.

The Caspian seal (Phoca caspica, Pusa caspica in some sources), which is endemic to the Caspian Sea, is one of very few seal species that live in inland waters (see also Baikal seal, Saimaa Ringed Seal). The area has given its name to several species of birds, including the Caspian gull and the Caspian tern. There are several species and subspecies of fish endemic to the Caspian Sea, including the kutum (also known as Caspian white fish), Caspian Marine Shad, Caspian roach, Caspian bream (some report that the Bream occurring in the Aral Sea is the same subspecies), and a Caspian "salmon" (a subspecies of trout, Salmo trutta caspiensis). The "Caspian salmon" is critically endangered.

Environmental issues

The Volga River, the largest in Europe, drains 20% of the European land area and is the source of 80% of the Caspian’s freshwater inflow. Its lower reaches are heavily developed with numerous unregulated releases of chemical and biological pollutants. Although existing data are sparse and of questionable quality, there is ample evidence to suggest that the Volga is one of the principal sources of transboundary contaminants into the Caspian. The magnitude of oil and gas extraction and transport activity constitute risks to water quality. Underwater oil and gas pipelines have been constructed or proposed, increasing potential environmental threats.

Hydrological characteristics

Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake. The Caspian became landlocked about 5.5 million years ago due to plate tectonics. The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation. Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans. The level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians[who?] claim that a medieval rising of the Caspian, perhaps caused by the Amu Darya changing its inflow to the Caspian from the 13th century to the 16th century, caused the coastal towns of Khazaria, such as Atil, to flood. In 2004, the water level was -28 metres, or 28 metres (92 ft) below sea level.

Over the centuries, Caspian Sea levels have changed in synchronicity with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic Oscillation. Thus levels in the Caspian sea relate to atmospheric conditions in the North Atlantic thousands of miles to the north and west. These factors make the Caspian Sea a valuable place to study the causes and effects of global climate change.

The last short-term sea-level cycle started with a sea-level fall of 3 m (9.84 ft) from 1929 to 1977, followed by a rise of 3 m (9.84 ft) from 1977 until 1995. Since then smaller oscillations have taken place.