Red Sea
Location of the Red Sea
The Red Sea is an inlet of the Indian Ocean between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb sound and the Gulf of Aden. In the north are the Sinai Peninsula, the Gulf of Aqaba or the Gulf of Eilat and the Gulf of Suez (leading to the Suez Canal). The Red Sea is a Global 200 ecoregion.
Occupying a part of the Great Rift Valley, the Red Sea has a surface area of roughly 174,000 square miles (450,000 km²): being roughly 1,200 miles (1,900 km) long and, at its widest point, over 190 miles (300 km) wide. It has a maximum depth of 8,200 feet (2,500 m) in the central median trench and an average depth of 1,640 feet (500 m), but there are also extensive shallow shelves, noted for their marine life and corals. The sea is the habitat of over 1,000 invertebrate species and 200 soft and hard corals and is the world's most northern tropical sea.
The Red Sea is regarded as one of the most saline water bodies in the world that is governed by the effects of the water circulation pattern, resulting from evaporation and wind stress in the Red Sea. Salinity ranges between 36 and 38 ‰.
Red Sea is a direct translation of the Latin Mare Erythraeum, Arabic Al-Baḥr Al-Aḥmar, and Tigrinya Qeyḥ bāḥrī.
The name of the sea does not indicate the color of the water since it is not red in color. It may signify the seasonal blooms of the red-colored cyanobacteria Trichodesmium erythraeum near the water surface. Some suggest that it refers to the mineral-rich red mountains nearby which are called Harei Edom. Edom, meaning "ruddy complexion", is also an alternative Hebrew name for the red-faced biblical character Esau (brother of Jacob), and the nation descended from him, the Edomites, which in turn provides yet another possible origin for Red Sea.
There is also speculation that the name Red Sea came from a mistranslation of what should have been Reed Sea in the Biblical account of the Exodus.
Another hypothesis is that the name comes from the Himarites, a local group whose own name means red.
Yet another theory favored by some modern scholars is the name red is referring to the direction south, the same way the Black Sea's name may refer to north. The basis of this theory is that some Asiatic languages used color words to refer to the cardinal directions.
A final theory suggests that it was named so because because it borders the Egyptian Desert which the ancient Egyptians called the Dashret or "red land"; therefore it would have been the sea of the red land.
History
The Egyptians were the first to attempt a mission of exploration in the Red Sea. In the Bible, the story of The Exodus tells how Moses, the son of a slave woman, leads the Israelites across its headwaters, (presumably the Reed Sea which has since disappeared because of the Suez Canal water diversion) to freedom, by using the powers of God to part the waters. However, it was a Greek sailor, Hippalus, who conferred an international dimension upon the Red Sea in his manifesto on the voyage of the Eritrea Sea and thus opened it up to an immense and exclusive trade with Asia. It was only from the 15th century onwards that Europe began to show interest in this area. In 1798, France charged General Bonaparte with invading Egypt and capturing the Red Sea. Although he failed in his mission, the engineer J.B. Lepere, who took part in it revitalised the plan for a canal which had been envisaged during the reign of the Pharaohs. The Suez Canal was opened in November 1869. At the time, the British, French, and Italians shared the trading posts. The posts were gradually dismantled following the First World War. After the Second World War, the Americans and Soviets exerted their influence whilst the volume of oil tanker traffic intensified. However, the Six Day War culminated in the closure of the Suez Canal from 1967 to 1975. Still today, in spite of patrols by the major maritime fleets in the waters of the Red Sea, the Suez Canal has never recovered its supremacy over the Cape route, which is believed to be less vulnerable.
Oceanography
The Red Sea lies between arid land, desert and semi-desert. The main reasons for the better development of reef systems along the Red Sea is because of its greater depths and an efficient water circulation pattern, The Red Sea water mass exchanges its water with the Arabian Sea, Indian Ocean via the Gulf of Aden. These physical factors reduce the effect of high salinity caused by evaporation and cold water in the north and relatively hot water in the south.
Climate
The climate of the Red Sea is the result of two distinct monsoon seasons; a northeasterly monsoon and a southwesterly monsoon. Monsoon winds occur because of the differential heating between the land surface and sea. Very high surface temperatures coupled with high salinities makes this one of the hottest and saltiest bodies of seawater in the world. The average surface water temperature of the Red Sea during the summer is about 26°C in the north and 30°C in the south, with only about 2°C variation during the winter months. The overall average water temperature is 22°C. The rainfall over the Red Sea and its coasts is extremely low averaging 0.06 m per year; the rain is mostly in the form of showers of short spells often associated with thunderstorms and occasionally with dust storms. The scarcity of rainfall and no major source of fresh water to the Red Sea result in the excess evaporation as high as 205 cm per yr and high salinity with minimal seasonal variation.
Salinity
The Red Sea is regarded as one of the most saline water bodies in the world that is governed by the effects of the water circulation pattern, resulting from evaporation and wind stress in the Red Sea. Salinity ranges between 36 and 38 ‰.
Tidal range
In general tide ranges between 0.6 m in the north, near the mouth of the Gulf of Suez and 0.9 m in the south near the Gulf of Aden but it fluctuates between 0.20 and 0.30 m away from the nodal point. The central Red Sea (Jeddah area) is therefore almost tideless, and as such the annual water level changes are more significant. Because of the small tidal range the water during high tide inundates the coastal sabkhas as a thin sheet of water up to a few hundred meters rather than inundating the sabkhas through a network of channels. However, south of Jeddah in the Shoiaba area the water from the lagoon may cover the adjoining sabkhas as far as 3 km whereas, north of Jeddah in the Al-kharrar area the sabkhas are covered by a thin sheet of water as far as 2 km. The prevailing north and northeastern winds influence the movement of water in the coastal inlets to the adjacent sabkhas, especially during storms. Winter mean sea level is 0.5 m higher than in summer. Tidal velocities passing through constrictions caused by reefs, sand bars and low islands commonly exceed 1-2 m per sec.
Current
In the Red Sea detailed current data is lacking, partially because they are weak and variable both spatially and temporally. Temporal and spatial currents variation is as low as 0.5 m and are governed mostly by wind. In summer NW winds drive surface water south for about four months at a velocity of 15-20 cm per sec., whereas in winter the flow is reversed resulting in the inflow of water from the Gulf of Aden into the Red Sea. The net value of the latter predominates, resulting in an overall drift to the northern end of the Red Sea. Generally the velocity of the tidal current is between 50-60 cm per sec with a maximum of 1 m per sec. at the mouth of the al-Kharrar Lagoon. However, the range of north-northeast current along the Saudi coast is 8-29 cm per sec.
Wind Regime
With the exception of the northern part of the Red Sea, which is dominated by persistent north-west winds, with speeds ranging between 7 and 12 km per hr., the rest of the Red Sea and the Gulf of Aden are subjected to the influence of regular and seasonally reversible winds. The wind regime is characterized by both seasonal and regional variations in speed and direction with average speed generally increasing northward.Wind is the driving force in the Red Sea for transporting the material either as suspension or as bedload. Wind induced currents play an important role in the Red Sea in initiating the process of resuspension of bottom sediments and transfer of materials from sites of dumping to sites of burial in quiescent environment of deposition. Wind generated current measurement is therefore important in order to determine the sediment dispersal pattern and its role in the erosion and accretion of the coastal rock exposure and the submerged coral beds.
Geology
Dust storm over the Red SeaThe Red Sea formed by Arabia splitting from Africa due to continental drift. This split started in the Eocene and accelerated during the Oligocene. The sea is still widening and it is considered that the sea will become an ocean in time (as proposed in the model of Tuzo Wilson).Sometimes during the Tertiary period the Bab el Mandeb closed and the Red Sea evaporated to an empty hot dry salt-floored sink. Effects causing this would be:-
A "race" between the Red Sea widening and Perim Island erupting filling the Bab el Mandeb with lava.
The lowering of world sea level during the Ice Ages due to much water being locked up in the ice caps.
Today surface water temperatures remain relatively constant at 70–77 °F (21–25 °C) and temperature and visibility remain good to around 660 feet (200 m), but the sea is known for its strong winds and tricky local currents.
In terms of salinity, the Red Sea is greater than the world average, approximately 4 percent. This is due to several factors: 1) high rate of evaporation and very little precipitation, 2) a lack of significant rivers or streams draining into the sea, and 3) limited connection with the Indian Ocean (and its lower water salinity).
Living resources
Red Sea holds one of the most spectacular coastal and marine environments of the world and has a rich biodiversityThe sea is known for its biological characteristics including its rich fauna and flora, particularly coral reefs and numerous fish species has a number of unique marine habitats, including sea-grass beds, salt-pans, mangroves, coral reefs and salt marshes.
Mineral resources
In terms of mineral resources the major constituents of the Red Sea sediments are as follows:
Biogenic constituents:
Nannofossils, foraminifera, pteropods, siliceous fossils
Volcanogenic constituents:
Tuffites, volcanic ash, montmorillonite, cristobalite, zeolites
Terrigenous constituents:
Quartz, feldspars, rock fragments, mica, heavy minerals, clay minerals
Authigenic minerals:
Sulfide minerals, aragonite, Mg-calcite, protodolomite, dolomite, quartz, chalcedony.
Evaporite minerals:
Magnesite, gypsum, anhydrite, halite, polyhalite
Brine precipitate:
Fe-montmorillonite, goethite, hematite, siderite, rhodochrosite, pyrite, sphalerite, anhydrite.
Desalination plants
The Red Sea water is an essential asset. There is extensive demand of desalinated water to meet the requirement of the population and the industries along the Red Sea.There are at least 18 desalination plants along the Red Sea coast of Saudi Arabia which discharge warm brine and treatment chemicals(chlorine and anti-scalants) that may cause bleaching and mortality of corals and diseases to the fish stocks. Although this is only a localized phenomenon, it may intensify with time and have a profound impact on the fishing industry.
The water from the Red Sea is also utilized by oil refineries and cement factories for cooling purposes. Used water drained back into the coastal zones may cause harm to the nearshore environment of the Red Sea.
Facts and figures at a glance
Length: ~1900 km - 79 % of the eastern Red Sea with numerous coastal inlets
Maximum Width: ~ 306 – 354 km – Massawa (Eritrea)
Minimum Width: ~ 26 – 29 km -Strait Bab al Mandeb (Yemen)
Average Width: ~ 280 km
Average Depth: ~ 490 m
Maximum Depth: ~2850 m
Total surface Area: 438 x 103- 450 x 103 km²
Volume: 215 x 103 –251 x 103 km³
Approximately 40 % of the Red Sea is quite shallow (under 100 m) whereas about 25 % of the Red Sea is under 50 m deep. About 15 % of the Red Sea is over 1000 m depth that forms the deep axial trough.
Shelf breaks are marked by coral reefs
Continental slope has an irregular profile (series of steps down to ~500 m)
Centre of Red Sea has a narrow trough (~ 1000 m; some deeps may exceed 2500 m)
Some of the research cruises in the Red Sea
Numerous research cruises have been conducted:
Arabia Felix (1761-1767)
Vitiaz (1886-1889)
Valdivia (1898-1894)
Pola (1897-98) Southern Red Sea and (1895/96 – Northern Red Sea
Ammiraglio Magnaghi (1923/24)
Snellius (1929 –1930)
Mabahiss (1933-1934 and 1934-1935)
Albatross (1948)
Manihine (1849 and 1952)
Calypso (1955)
Atlantis and Vema (1958)
Xarifa (1961)
Meteor (1961)
Glomar Challenger (1971)
Sonne 1997
Meteor 1999
Tourism
The sea is known for its spectacular dive sites such as Ras Mohammed, SS Thistlegorm (ship wreck), Elphinstone, The Brothers and Rocky Island in Egypt, Dolphin Reef in Eilat, Israel and less known sites in Sudan such as Sanganeb, Abington, Angarosh and Shaab Rumi.
The Red Sea was "discovered" as a diving destination by Hans Hass in the 1950s, and by Jacques-Yves Cousteau later. Popular tourist resorts include Sharm-El-Sheikh and Hurghada (and recently Marsa Alam) in Egypt, as well as Eilat, Israel in an area known as the Red Sea Riviera.
Mediterranean Sea
The Mediterranean Sea is a sea of the Atlantic Ocean almost completely enclosed by land: on the north by Europe, on the south by Africa, and on the east by Asia. It covers an approximate area of 2.5 million km² (965 000 mi²), 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.
It was a superhighway of transport in ancient times, allowing for trade and cultural exchange between emergent peoples of the region — the Mesopotamian, Egyptian, Semitic, Persian, Phoenician, Carthaginian, Greek, Roman and Turkish cultures. The history of the Mediterranean is important in understanding the origin and development of Western Civilizaton.
Name
The Mediterranean Sea has been known by a number of alternative names throughout human history. It was, for example, commonly called Mare Nostrum (Latin, Our Sea), and occasionally Mare Internum by the Romans. (Sallust, Jug. 17). In the Old Testament, on the west coast of the Holy Land, and therefore behind a person facing the east, it is called the "Hinder Sea", sometimes translated as "Western Sea", (Deut. xi. 24; Joel, ii. 20), and also the "Sea of the Philistines" (Exod. xxii. 81), because that people occupied a large portion of its shores near the Israelites. Mostly, however, it was the "Great Sea" (Num. xxxiv. 6, 7; Josh. i. 4, ix. 1, xv. 47; Ezek. xlvii. 10, 15, 20), or simply "The Sea" (1 Kings, v. 9; comp. 1 Macc. xiv. 34. xv. 11). In Hebrew, it is called "ha-Yam ha-Tikhon" , "the middle sea", a literal adaptation of the German equivalent Mittelmeer. In Turkish, it is Akdeniz, "the white sea". In Arabic, it is Al-Baħr Al-Abyad Al-Muttawasit, "the middle white sea".
Georgraphy and Climate
The Mediterranean Sea is connected to the Atlantic Ocean by the Strait of Gibraltar on the west and to the Sea of Marmara and 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 man-made Suez Canal in the south-east connects the Mediterranean Sea with the Red Sea.
Large islands in the Mediterranean include Cyprus, Crete, Euboea, Rhodes, Lesbos, Chios, Kefalonia and Corfu in the eastern Mediterranean; Sardinia, Corsica, Sicily, and Malta in the central Mediterranean; and Ibiza, Majorca and Minorca (the Balearic Islands) in the western Mediterranean.The Mediterranean climate is generally one of wet winters and hot, dry summers. Crops of the region include olives, grapes, oranges, tangerines, and cork.
Oceanography
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 imposing deep blue color, especially around Greek islands.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 open ocean, this chemically-distinct Mediterranean Intermediate Water can persist thousands of kilometers awayfrom its source.
Bordering Countries
Twenty-one modern states have a coastline on the Mediterranean Sea. They are:
Europe (from west to east): Spain, France, Monaco, Italy, the island state of Malta, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania, Greece, Turkey, and the island Republic of Cyprus
Asia (from north to south): Turkey, Syria, Lebanon and Israel.
Africa (from east to west): Egypt, Libya, Tunisia, Algeria and Morocco
Several other territories also border the Mediterranean Sea (from west to east):
The Crown colony of Gibraltar
The Spanish exclaves of Ceuta and Melilla and nearby islands
The autonomous monastic state of Mount Athos
The sovereign base area of Akrotiri and Dhekelia
The Gaza Strip (governed by the Palestinian National Authority)
Portugal, Serbia 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 their cultural affinity with other Mediterranean countries.
Geology
The geology of the Mediterranean is complex, involving the break-up and then collision of the African and Eurasian plates, and the Messinian Salinity Crisis in the late Miocene when the Mediterranean dried up.The Mediterranean Sea has an average depth of 1,500 m and the deepest recorded point is 5267 meters (about 3.27 miles) in the Calypso Deep in the Ionian Sea. The coastline extends for 46,000 km. 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 km² and the Eastern Mediterranean about 1.65 million km².
In the last few centuries, mankind has done much to alter Mediterranean geology. Structures have been
built all along the coastlines, exacerbating and rerouting erosional patterns. Many pollution-producing boats travel the sea that unbalance the natural chemical ratios of the region. Beaches have been mismanaged, and the overuse of the sea's natural and marine resources continues to be a problem. This misuse speeds along and/or confounds natural processes. The actual geography has also been altered by the building of dams and canals. 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. Neotethys formed during the Late Triassic and Early Jurassic rifting of the African and Eurasian plates.
Ecology
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 opening of the Suez Canal in 1869 created the first salt-water passage between the Mediterranean and Red seas. 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 hypersaline 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. 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, which has made conditions there even more like the Red Sea. This species exchange is known as the Lessepsian Migration, after Ferdinand de Lesseps, the engineer who oversaw the canal's construction.
Source: Wikipedia |
