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Composite satellite image of the Mediterranean Sea.
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by Africa, and on the east by the Levant. The sea is technically a part of the Atlantic Ocean, although it is usually identified as a completely separate body of water. The name Mediterranean is derived from the Latin ''mediterraneanus'', meaning "inland" or "in the middle of the earth" (from ''medius'', "middle" and ''terra'', "earth"). It covers an approximate area of 2.5 million kmÂ² (965,000 sq mi), but its connection to the Atlantic (the Strait of Gibraltar) is only 14 km (9 mi) wide. In oceanography, it is sometimes called the ''Eurafrican Mediterranean Sea'' or the ''European Mediterranean Sea'' to distinguish it from mediterranean seas elsewhere.
The Mediterranean Sea has an average depth of 1,500 metres (4,920 ft) and the deepest recorded point is 5,267 metres (about 3.27 miles) in the Calypso Deep in the Ionian Sea.
It was an important route for merchants and travelers of ancient times that allowed for trade and cultural exchange between emergent peoples of the region — the Mesopotamian, Egyptian, Phoenician, Carthaginian, Greek, Illyrian, Levantine, Roman, Moorish, Slavic and Turkish cultures. The history of the Mediterranean region is crucial to understanding the origins and development of many modern societies. "For the three quarters of the globe, the Mediterranean Sea is similarly the uniting element and the centre of World History."
The term ''Mediterranean'' derives from the Latin word ''mediterraneus'', meaning "in the middle of earth" (''medius'', "middle" + ''terra'', "land, earth"). This is either due to the sea being surrounded by land (especially compared to the Atlantic Ocean) or that it was at the centre of the known world.
The Mediterranean Sea has been known by a number of alternative names throughout human history. For example the Romans commonly called it ''Mare Nostrum'' (Latin, "Our Sea"). Occasionally it was known as ''Mare Internum'' by (Sallust, ''Jug.'' 17). Other examples of alternative names include ''Mesogeios'' (ÎÎµÏÏÎ³ÎµÎ¹Î¿Ï), meaning "inland, interior" (from Î¼ÎµÏÎ¿, "middle" + Î³Î±Î¹Î¿Ï, "land, earth") in Greek.
Biblically, it has been called the "Hinder Sea", due to its location on the west coast of the Holy Land, and therefore behind a person facing the east, as referenced in the Old Testament, and sometimes translated as "Western Sea", (Deut. 11:24; Joel 2:20), and also the "Sea of the Philistines" (Exod. 23:31), due to the peoples occupying a large portion of its shores near the Israelites. However, primarily it was known as the "Great Sea" (Num. 34:6,7; Josh. 1:4, 9:1, 15:47; Ezek. 47:10,15,20), or simply "The Sea" (1 Kings 5:9; ''comp.'' 1 Macc. 14:34, 15:11).
In Modern Hebrew, it has been called ''Hayam Hatikhon'' (×Ö·×Ö¸Ö¼× ×Ö·×ªÖ´Ö¼×××Ö¹×), "the middle sea", a literal adaptation of the German equivalent ''Mittelmeer''. In Turkish, it is known as ''Akdeniz'', "the white sea". In modern Arabic, it is known as ' (Ø§ÙØ¨ØØ± Ø§ÙØ£Ø¨ÙØ¶ Ø§ÙÙ
ØªÙØ³Ø·), "the White Middle Sea." And, lastly, in Islamic and older Arabic literature, it was referenced as ' (Ø¨ØØ± Ø§ÙØ±ÙÙ
), or "the Roman/Byzantine Sea."
As a sea around which some of the most ancient human civilizations were arranged, it has had a major influence on the history and ways of life of these cultures. It provided a way of trade, colonization and war, and was the basis of life (via fishing and the gathering of other seafood) for numerous communities throughout the ages.
The combination of similarly-shared climate, geology and access to a common sea has led to numerous historical and cultural connections between the ancient and modern societies around the Mediterranean.
Geography and climate
A satellite image taken from the side of the Strait of Gibraltar. At left, Europe: at right, Africa.
The Mediterranean Sea is connected to the Atlantic Ocean by the Strait of Gibraltar on the west and to the Sea of Marmara and the Black Sea, by the Dardanelles and the Bosporus respectively, on the east. The Sea of Marmara is often considered a part of the Mediterranean Sea, whereas the Black Sea is generally not. The long man-made Suez Canal in the southeast connects the Mediterranean Sea to the Red Sea.
Large islands in the Mediterranean include Cyprus, Crete, Euboea, Rhodes, Lesbos, Chios, Kefalonia, Corfu, Naxos and Andros in the eastern Mediterranean; Sardinia, Corsica, Sicily, Cres, Krk, BraÄ, Hvar, Pag, KorÄula and Malta in the central Mediterranean; and Ibiza, Majorca and Minorca (the Balearic Islands) in the western Mediterranean.
The climate is a typical Mediterranean climate with hot, dry summers and mild, rainy winters. Crops of the region include olives, grapes, oranges, tangerines, and cork.
Predominant currents for June.
Being nearly landlocked affects the Mediterranean Sea's properties; for instance, tides are very limited as a result of the narrow connection with the Atlantic Ocean. The Mediterranean is characterized and immediately recognized by its deep blue color.
Evaporation greatly exceeds precipitation and river runoff in the Mediterranean, a fact that is central to the water circulation within the basin. Evaporation is especially high in its eastern half, causing the water level to decrease and salinity to increase eastward. This pressure gradient pushes relatively cool, low-salinity water from the Atlantic across the basin; it warms and becomes saltier as it travels east, then sinks in the region of the Levant and circulates westward, to spill over the Strait of Gibraltar. Thus, seawater flow is eastward in the Strait's surface waters, and westward below; once in the Atlantic, this chemically distinct "Mediterranean Intermediate Water" can persist thousands of kilometers away from its source.
Map of the Mediterranean Sea.
Twenty-one modern states have a coastline on the Mediterranean Sea. They are:
*Europe (from west to east): Spain, France, Monaco, Italy, Malta, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania, Greece and Turkey
*Asia (from north to south): Turkey, Cyprus, Syria, Lebanon, Israel and Egypt
*Africa (from east to west): Egypt, Libya, Tunisia, Algeria and Morocco
Turkey and Egypt are transcontinental countries. The southernmost islands of Italy, the Pelagie islands, are geologically part of the African continent.
Several other territories also border the Mediterranean Sea (from west to east):
* The British overseas territory of Gibraltar
* The Spanish enclaves of Ceuta and Melilla and nearby islands
* The British sovereign base area of Akrotiri and Dhekelia
* The Palestinian Territories
Andorra, Jordan, Portugal, San Marino and the Vatican City, although they do not border the sea, are often considered Mediterranean countries in a wider sense due to their Mediterranean climate, fauna and flora, and/or their cultural affinity with other Mediterranean countries.
Capital cities of sovereign countries and major cities with populations larger than 200,000 people bordering the Mediterranean Sea are: Malaga, Valencia, Barcelona, Marseille, Nice, Monaco, Genoa, Rome, Naples, Palermo, Valetta, Messina, Bari, Venice, Trieste, Split, Dubrovnik, DurrÃ«s, Athens, Thessaloniki, Istanbul, Izmir, Antalya, Mersin, Tarsus, Adana, Lattakia, Tripoli (Lebanon), Beirut, Haifa, Tel Aviv, Ashdod, Port Said, Damietta, Alexandria, Benghazi, Tripoli (Libya), Sfax, Tunis, Annaba, Algiers and Oran.
According to the International Hydrographic Organization (IHO) treaties, the Mediterranean Sea is subdivided into a number of smaller seas, each with their own designation (from west to east):
* the Alboran Sea, between Spain and Morocco,
* the Balearic Sea, between mainland Spain and its Balearic Islands,
* the Ligurian Sea between Corsica and Liguria (Italy),
* the Adriatic Sea between Italy, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro and Albania
* the Ionian Sea between Italy, Albania and Greece
* the Aegean Sea between Greece and Turkey
* the Sea of Marmara between the Aegean and Black Sea
Although not recognized by the IHO treaties, there are some other seas whose names have been in common use from the ancient times, or in the present:
* the Catalan Sea, between Iberian Peninsula and Balearic Islands, as a part of the Balearic Sea
* the Sea of Sardinia, between Sardinia and Balearic Islands, as a part of the Balearic Sea
* the Tyrrhenian Sea enclosed by Sardinia, Italian peninsula and Sicily,
* the Sea of Sicily between Sicily and Tunisia,
* the Libyan Sea between Libya and Crete,
* In the Aegean Sea,
** the Thracian Sea in its north,
** the Myrtoan Sea between the Cyclades and the Peloponnese,
** the Sea of Crete north of Crete
* the Cilician Sea between Turkey and Cyprus
Many of these smaller seas feature in local myth and folklore and derive their names from these associations. In addition to the seas, a number of gulfs and straits are also recognised:
*the Saint George Bay in Beirut, Lebanon
*the Strait of Gibraltar, connects the Atlantic Ocean to the Mediterranean Sea and separates Spain from Morocco
*the Bay of Gibraltar, at the southern end of the Iberian Peninsula
*the Gulf of Corinth, an enclosed sea between the Ionian Sea and the Corinth Canal
*the Pagasetic Gulf, the gulf of Volos, south of the Thermaic Gulf, formed by the Mount Pelion peninsula
*the Saronic Gulf, the gulf of Athens, between the Corinth Canal and the Mirtoan Sea
*the Thermaic Gulf, the gulf of Thessaloniki, located in the northern Greek region of Macedonia
*the Kvarner Gulf, Croatia
*the Gulf of Lion, south of France
*the Gulf of Valencia, east of Spain
*the Strait of Messina, between Sicily and the toe of Italy
*the Gulf of Genoa, northwestern Italy
*the Gulf of Venice, northeastern Italy
*the Gulf of Trieste, northeastern Italy
*the Gulf of Taranto, southern Italy
*the Gulf of Salerno, southwestern Italy
*the Gulf of Gaeta, southwestern Italy
*the Gulf of Squillace, southern Italy
*the Strait of Otranto, between Italy and Albania
*the Gulf of Haifa, between Haifa and Akko, Israel
*the Gulf of Sidra, between Tunisia and Cyrenaica (eastern Libya)
*the Strait of Sicily, between Sicily and Tunisia
*the Corsica Channel, between Corsica and Italy
*the Strait of Bonifacio, between Sardinia and Corsica
*the Gulf of Ä°skenderun, between Ä°skenderun and Adana (Turkey)
*the Gulf of Antalya, between west and east shores of Antalya (Turkey)
*the Bay of Kotor, in south-western Montenegro and south-eastern Croatia
*the Malta Channel, between Sicily and Malta
The geologic history of the Mediterranean is complex. It was involved in the tectonic break-up and then collision of the African and Eurasian plates. The Messinian Salinity Crisis occurred in the late Miocene when the Mediterranean dried up. Geologically the Mediterranean is underlain by oceanic crust.
The Mediterranean Sea has an average depth of and the deepest recorded point is 5,267 meters (about 3.27 miles) in the Calypso Deep in the Ionian Sea. The coastline extends for . A shallow submarine ridge (the Strait of Sicily) between the island of Sicily and the coast of Tunisia divides the sea in two main subregions (which in turn are divided into subdivisions), the Western Mediterranean and the Eastern Mediterranean. The Western Mediterranean covers an area of about 0.85 million kmÂ² (0.33 million sq mi) and the Eastern Mediterranean about 1.65 million kmÂ² (0.64 million sq mi).
The geodynamic evolution of the Mediterranean Sea was provided by the convergence of European and African plates. This process was driven by the differential spreading along the Atlantic ridge, which led to the closure of the Tethys Ocean and eventually to the Alpine orogenesis. However, the Mediterranean also hosts wide extensional basins and migrating tectonic arcs, in response to its land-locked configuration.
Eastern Mediterranean =
In middle Miocene times, the collision between the Arabian microplate and Eurasia led to the separation between the Tethys and the Indian oceans. This process resulted in profound changes in the oceanic circulation patterns, which shifted global climates towards colder conditions. The Hellenic Arc, which has a land-locked configuration, underwent a widespread extension for the last 20 Myr due to a slab roll-back process. In addition, the Hellenic Arc experienced a rapid rotation phase during the Pleistocene, with a counterclockwise component in its eastern portion and a clockwise trend in the western segment.
Central Mediterranean =
The opening of small oceanic basins of the central Mediterranean follows a trench migration and back-arc opening process that occurred during the last 30 Myr. This phase was characterized by the counterclockwise rotation of the Corsica-Sardinia block, which lasted until the Langhian (ca.16 Ma), and was in turn followed by a slab detachment along the northern African margin. Subsequently, a shift of this active extentional deformation led to the opening of the Tyrrenian basin.
Western Mediterranean =
Since Mesozoic to Tertiary times, during convergence between Africa and Iberia, the Betic-Rif mountain belts developed. Tectonic models for its evolution include: rapid motion of Alboran microplate, subduction zone and radial extensional collapse caused by convective removal of lithospheric mantle. The development of these intramontane Betic and Rif basins led to the onset of two marine gateways which were progressively closed during the late Miocene by an interplay of tectonic and glacio-eustatic processes.
Its semi-enclosed configuration makes the oceanic gateways critical in controlling circulation and environmental evolution in the Mediterranean Sea. Water circulation patterns are driven by a number of interactive factors, such as climate and bathymetry, which can lead to precipitation of evaporites. During late Miocene times, a so-called "Messinian Salinity Crisis" (MSC hereafter) occurred, which was triggered by the closure of the Atlantic gateway. Evaporites accumulated in the Red Sea Basin (late Miocene), in the Carpatian foredeep (middle Miocene) and in the whole Mediterranean area (Messinian).
An accurate age estimate of the MSCâ5.96 Maâhas recently been astronomically achieved; furthermore, this event seems to have occurred synchronously. The beginning of the MSC is supposed to have been of tectonic origin; however, an astronomical control (eccentricity) might also have been involved. In the Mediterranean basin, diatomites are regularly found underneath the evaporite deposits, thus suggesting (albeit not clearly so far) a connection between their geneses.
The present-day Atlantic gateway, i.e. the Strait of Gibraltar, finds its origin in the early Pliocene. However, two other connections between the Atlantic Ocean and the Mediterranean Sea existed in the past: the Betic Corridor (southern Spain) and the Rifian Corridor (northern Morocco). The former closed during Tortonian times, thus providing a "Tortonian Salinity Crisis" well before the MSC; the latter closed about 6 Ma, allowing exchanges in the mammal fauna between Africa and Europe.
Nowadays, evaporation is more relevant than the water yield supplied by riverine water and precipitation, so that salinity in the Mediterranean is higher than in the Atlantic. These conditions result in the outflow of warm saline Mediterranean deep water across Gibraltar, which is in turn counterbalanced by an inflow of a less saline surface current of cold oceanic water.
The Mediterranean was once thought to be the remnant of the Tethys Ocean. It is now known to be a structurally younger ocean basin known as Neotethys. The Neotethys formed during the Late Triassic and Early Jurassic rifting of the African and Eurasian plates.
Because of its latitudinal position and its land-locked configuration, the Mediterranean is especially sensitive to astronomically induced climatic variations, which are well documented in its sedimentary record. Since the Mediterranean is involved in the deposition of eolian dust from the Sahara during dry periods, whereas riverine detrital input prevails during wet ones, the Mediterranean marine sapropel-bearing sequences provide high-resolution climatic information. These data have been employed in reconstructing astronomically calibrated time scales for the last 9 Ma of the Earth's history. Furthermore, the exceptional accuracy of these paleoclimatic records improved our knowledge of the Earth's orbital variations in the past.
Ecology and biota
Turqueta beach, in the Spanish island of Menorca.
As a result of the drying of the sea during the Messinian Salinity Crisis, the marine biota of the Mediterranean are derived primarily from the Atlantic Ocean. The North Atlantic is considerably colder and more nutrient-rich than the Mediterranean, and the marine life of the Mediterranean has had to adapt to its differing conditions in the five million years since the basin was reflooded.
The Alboran Sea is a transition zone between the two seas, containing a mix of Mediterranean and Atlantic species. The Alboran Sea has the largest population of Bottlenose Dolphins in the western Mediterranean, is home to the last population of harbour porpoises in the Mediterranean, and is the most important feeding grounds for Loggerhead Sea Turtles in Europe. The Alboran sea also hosts important commercial fisheries, including sardines and swordfish. In 2003, the World Wildlife Fund raised concerns about the widespread drift net fishing endangering populations of dolphins, turtles, and other marine animals.
The opening of the Suez Canal in 1869 created the first salt-water passage between the Mediterranean and Red Sea. The Red Sea is higher than the Eastern Mediterranean, so the canal serves as a tidal strait that pours Red Sea water into the Mediterranean. The Bitter Lakes, which are hyper-saline natural lakes that form part of the canal, blocked the migration of Red Sea species into the Mediterranean for many decades, but as the salinity of the lakes gradually equalized with that of the Red Sea, the barrier to migration was removed, and plants and animals from the Red Sea have begun to colonize the Eastern Mediterranean. The Red Sea is generally saltier and more nutrient-poor than the Atlantic, so the Red Sea species have advantages over Atlantic species in the salty and nutrient-poor Eastern Mediterranean. Accordingly, Red Sea species invade the Mediterranean biota, and not vice versa; this phenomenon is known as the Lessepsian migration (after Ferdinand de Lesseps, the French engineer) or Erythrean invasion. The construction of the Aswan High Dam across the Nile River in the 1960s reduced the inflow of freshwater and nutrient-rich silt from the Nile into the Eastern Mediterranean, making conditions there even more like the Red Sea and worsening the impact of the invasive species.
Invasive species have become a major component of the Mediterranean ecosystem and have serious impacts on the Mediterranean ecology, endangering many local and endemic Mediterranean species. A first look at some groups of exotic species show that more than 70% of the non-indigenous decapods and about 63% of the exotic fishes occurring in the Mediterranean are of Indo Pacific origin, introduced into the Mediterranean through the Suez Canal. This makes the Canal as the first pathway of arrival of âalienâ species into the Mediterranean. The impacts of some lessepsian species have proven to be considerable mainly in the Levantine basin of the Mediterranean, where they are replacing native species and becoming a âfamiliar sightâ.
According to the International Union for Conservation of Nature definition, as well as Convention on Biological Diversity(CBD) and Ramsar Convention terminologies, they are alien species, as they are non native (non-indigenous) to the Mediterranean Sea, and they are outside their normal area of distribution which is the Indo-Pacific region. When these species succeed in establishing populations in the Mediterranean sea, compete with and begin to replace native species they are âAlien Invasive Speciesâ, as they are an agent of change and a threat to the native biodiversity. Depending on their impact, Lessepsian migrants are either alien or alien invasive species. In the context of CBD, âintroduction" refers to the movement by human agency, indirect or direct, of an alien species outside of its natural range (past or present). The Suez Canal, being a artificial (man made) canal, is a human agency. Lessepsian migrants are therefore âintroducedâ species (indirect, and unintentional). Whatever wording is chosen, they represent a threat to the native Mediterranean biodiversity, because they are non-indigenous to this sea. In recent years, the Egyptian government's announcement of its intentions to deepen and widen the canal have raised concerns from marine biologists, fearing that such an act will only worsen the invasion of Red Sea species into the Mediterranean, facilitating the crossing of the canal for yet additional species.
Arrival of new tropical Atlantic species
In recent decades, the arrival of exotic species from the tropical Atlantic has become a noticeable feature. Whether this reflects an expansion of the natural area of these species that now enter the Mediterranean through the Gibraltar straight, because of a warming trend of the water caused by Global Warming; or an extension of the maritime traffic; or is simply the result of a more intense scientific investigation, is still an open question. While not as intense as the âlessepsianâ movement, the process deserves to be studied and monitored.
Europe may be less threatened by sea-level rise than many developing country regions. However, coastal ecosystems do appear to be threatened, especially enclosed seas such as the Baltic, the Mediterranean and the Black Sea. These seas have only small and primarily east-west orientated movement corridors, which may restrict northward displacement of organisms in these areas. Sea level rise for the next century (2100) could be between 30 and 100 cm and temperature shifts of a mere 0.05-0.1Â°C in the deep sea are sufficient to induce significant changes in species richness and functional diversity.
Pollution in this region has been extremely high in recent years. The United Nations Environment Programme has estimated that 650 million tons of sewage, 129,000 tons of mineral oil, 60,000 tons of mercury, 3,800 tons of lead and 36,000 tons of phosphates are dumped into the Mediterranean each year. The Barcelona Convention aims to 'reduce pollution in the Mediterranean Sea and protect and improve the marine environment in the area, thereby contributing to its sustainable development.'
Many marine species have been almost wiped out because of the sea's pollution. One of them is the Mediterranean Monk Seal which is considered to be among the world's most endangered marine mammals.
The Mediterranean is also plagued by marine debris. A 1994 study of the seabed using trawl nets around the coasts of Spain, France and Italy reported a particularly high mean concentration of debris; an average of 1,935 items per square kilometre. Plastic debris accounted for 76%, of which 94% was plastic bags.
Some of the worldâs busiest shipping routes are in the Mediterranean Sea. It is estimated that approximately 220,000 vessels of more than 100 tonnes cross the Mediterranean Sea each year â about one third of the worldâs total merchant shipping. These ships often carry hazardous cargo, which if lost would result in severe damage to the marine environment.
The discharge of chemical tank washings and oily wastes also represent a significant source of marine pollution. The Mediterranean Sea constitutes 0.7 percent of the global water surface and yet receives seventeen percent of global marine oil pollution. It is estimated that every year between 100,000 and 150,000 tonnes of crude oil are deliberately released into the sea from shipping activities.
Approximately 370 million tonnes of oil are transported annually in the Mediterranean Sea (more than 20 percent of the world total), with around 250 to 300 oil tankers crossing the Sea every day. Accidental oil spills happen frequently with an average of 10 spills per year. A major oil spill could occur at any time in any part of the Mediterranean.
With a unique combination of pleasant climate, beautiful coastline, rich history and diverse culture the Mediterranean region is the most popular tourist destination in the world - attracting approximately one third of the worldâs international tourists.
Tourism is one of the most important sources of income for many Mediterranean countries. It also supports small communities in coastal areas and islands by providing alternative sources of income far from urban centres. However, tourism has also played major role in the degradation of the coastal and marine environment. Rapid development has been encouraged by Mediterranean governments to support the large numbers of tourists visiting the region each year. But this has caused serious disturbance to marine habitats such as erosion and pollution in many places along the Mediterranean coasts.
Tourism often concentrates in areas of high natural wealth, causing a serious threat to the habitats of endangered Mediterranean species such as sea turtles and monk seals. It is ironic that tourism in this region is destroying the foundations of its own existence. And it is inevitable that the tourists will leave the Mediterranean as it becomes more depleted of its natural beauty.
Fish stock levels in the Mediterranean Sea are alarmingly low. The European Environment Agency says that over 65 percent of all fish stocks in the region are outside safe biological limits and the United Nations Food and Agriculture Organisation, that some of the most important fisheries â such as albacore and bluefin tuna, hake, marlin, swordfish, red mullet and sea bream - are threatened.
There are clear indications that catch size and quality have declined, often dramatically, and in many areas larger and longer-lived species have disappeared entirely from commercial catches.
Large open water fish like tuna have been a shared fisheries resource for thousands of years but the stocks are now dangerously low. In 1999 Greenpeace published a report revealing that the amount of bluefin tuna in the Mediterranean had decreased by over 80 percent in the previous 20 years and government scientists warn that without immediate action the stock will collapse.
Aquaculture is expanding rapidly - often without proper environmental assessment â and currently accounts for 30% of the fish protein consumed worldwide. The industry claims that farmed seafood lessens the pressure on wild fish stocks, yet many of the farmed species are carnivorous, consuming up to five times their weight in wild fish.
Mediterranean coastal areas are already over exposed to human influence, with pristine areas becoming ever scarcer. The aquaculture sector adds to this pressure, requiring areas of high water quality to set up farms. The installation of fish farms close to vulnerable and important habitats such as seagrass meadows is particularly concerning.
Aquaculture production in the Mediterranean also threatens biodiversity through the introduction of new species to the region, the impact of the farms' organic and chemical effluents on the surrounding environment and coastal habitat destruction.