Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez (leading to the Suez Canal). The Red Sea is a Global 200 ecoregion. The sea is underlain by the Red Sea Rift which is part of the Great Rift Valley.

The Red Sea has a surface area of roughly 438,000 km² (169,100 mi²). It is about 2250 km (1398 mi) long and, at its widest point, 355 km (220.6 mi) wide. It has a maximum depth of 2211 m (7254 ft) in the central median trench, and an average depth of 490 m (1,608 ft). However, 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. It is the world's northernmost tropical sea.

The International Hydrographic Organization defines the limits of the Red Sea as follows:Extent

On the North. The Southern limits of the Gulfs of Suez [A line running from Ràs Muhammed (27°43'N) to the South point ofShadwan Island (34°02'E) and thence Westward on a parallel (27°27'N) to the coast of Africa] and Aqaba [A line running from Ràs al Fasma Southwesterly to Requin Island (27°57′N 34°36′E) through Tiran Island to the Southwest point thereof and thence Westward on a parallel (27°54'N) to the coast of the Sinaï Peninsula].

On the South. A line joining Husn Murad (12°40′N 43°30′E) and Ras Siyyan (12°29′N 43°20′E).

Name

Some ancient geographers called the Red Sea the Arabian Gulf or Gulf of Arabia.  Red Sea is a direct translation of the Greek Erythra Thalassa  and Latin Mare Rubrum (alternatively Sinus Arabicus, literally "Arabian Gulf"), Arabic Al-Baḥr Al-Aḥmar or Baḥr Al-Qalzam, Somali Badda Cas and Tigrinya Qeyyiḥ bāḥrī  . The name of the sea may signify the seasonal blooms of the red-coloured Trichodesmium erythraeum near the water's surface. A theory favored by some modern scholars  is that the name red is referring to the direction South, just as 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.Herodotus on one occasion uses Red Sea and Southern Sea interchangeably. 

The association of the Red Sea with the Biblical account of the Israelite Crossing the Red Sea is ancient, and was made explicit in the Septuaginttranslation of the Book of Exodus from Hebrew to Koine Greek in approximately the third century B.C. In that version, the Hebrew Yam Suph   is translated as Erythra Thalassa (Red Sea). (See also the more recent suggestion that the Yam Suph of the Exodus refers to a Sea of Reeds). The Red Sea is one of four seas named in English after common color terms — the others being the Black Sea, the White Sea and the Yellow Sea. The direct rendition of the Greek Erythra thalassa in Latin as Mare Erythraeum refers to the north-western part of the Indian Ocean, and also to a region on Mars.

History

In the 6th century BC, Darius the Great of Persia sent reconnaissance missions to the Red Sea, improving and extending navigation by locating many hazardous rocks and currents. A canal was built between the Nile and the northern end of the Red Sea at Suez. In the late 4th century BC,Alexander the Great sent Greek naval expeditions down the Red Sea to the Indian Ocean. Greek navigators continued to explore and compile data on the Red Sea. Agatharchides collected information about the sea in the 2nd century BC. The Periplus of the Erythraean Sea ("Periplus of the Red Sea"), a Greek periplus written by an unknown author around the 1st century AD, contain a detailed description of the Red Sea's ports and sea routes. The Periplus also describes how Hippalus first discovered the direct route from the Red Sea to India.The earliest known exploration of the Red Sea was conducted by Ancient Egyptians, as they attempted to establish commercial routes to Punt. One such expedition took place around 2500 BC, and another around 1500 BC ( by Hatshepsut ). Both involved long voyages down the Red Sea.The Biblical Book of Exodus tells the story of the Israelites' miraculous crossing of a body of water, which the Hebrew text calls Yam Suph. Yam Suph is traditionally identified as the Red Sea. The account is part of the Israelites' escape from slavery in Egypt. Yam Suph can also been translated as Sea of Reeds.

During the Middle Ages, the Red Sea was an important part of the Spice trade route. In 1513, trying to secure that channel to Portugal, Afonso de Albuquerque laid siege to Aden. but was forced to retreat. They cruised the Red Sea inside the Bab al-Mandab, as the first European fleet to have sailed this waters.The Red Sea was favored for Roman trade with India starting with the reign of Augustus, when the Roman Empire gained control over the Mediterranean, Egypt, and the northern Red Sea. The route had been used by previous states but grew in the volume of traffic under the Romans. From Indian ports goods from China were introduced to the Roman world. Contact between Rome and China depended on the Red Sea, but the route was broken by the Aksumite Empire around the 3rd century AD.

In 1798, France ordered General Bonaparte to invade Egypt and take control of the Red Sea. Although he failed in his mission, the engineer Jean-Baptiste Lepère, who took part in it, revitalised the plan for a canal which had been envisaged during the reign of the Pharaohs. Several canals were built in ancient times from the Nile to the Red Sea along or near the line of the present Sweet Water Canal, but none lasted for long. The Suez Canalwas 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. 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 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 (79 °F) in the north and 30 °C (86 °F) in the south, with only about 2 °C (3.6 °F) variation during the winter months. The overall average water temperature is 22 °C (72 °F). Today surface water temperatures remain relatively constant at 21–25 °C (70–77 °F). Temperature and visibility remain good to around 200 m (656 ft). The sea is known for its strong winds and unpredictable local currents.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 theArabian Sea, Indian Ocean via the Gulf of Aden. These physical factors reduce the effect of high salinity caused by evaporation water in the north and relatively hot water in the south.

The rainfall over the Red Sea and its coasts is extremely low, averaging 0.06 m (2.36 in) 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 (81 in) per year and high salinity with minimal seasonal variation. A recent underwater expedition to the Red Sea offshore from Sudan and Eritrea found surface water temperatures 28 °C in winter and up to 34 °C in the summer, but despite that extreme heat the coral was healthy with much fish life with very little sign of coral bleaching, with only 9% infected by thalassomonas loyana, the 'white plague' agent. Favia favus coral there harbours a virus, BA3, which kills T.loyana. Plans are afoot to use samples of these corals' apparently heat-adapted commensal algae to salvage bleached coral elsewhere.

Salinity

The Red Sea is one of the most saline bodies of water in the world, owing to high evaporation. Salinity ranges from between ~36 ‰ in the southern part because of the effect of the Gulf of Aden water and reaches 41 ‰ in the northern part, owing mainly to the Gulf of Suezwater and the high evaporation. The average salinity is 40 ‰. (Average salinity for the world's seawater is ~35 ‰ on the Practical Salinity Scale, or PPS; that translates to 3.5% actual dissolved salts.)

The salinity of 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. Lack of significant rivers or streams draining into the sea.
3. Limited connection with the Indian Ocean, which has lower water salinity.

Tidal range

In general tide ranges between 0.6 m (2.0 ft) in the north, near the mouth of the Gulf of Suez and 0.9 m (3.0 ft) in the south near the Gulf of Aden but it fluctuates between 0.20 m (0.66 ft) and 0.30 m (0.98 ft) 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 metres 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 (2 mi) whereas, north of Jeddah in the Al-kharrar area the sabkhas are covered by a thin sheet of water as far as 2 km (1.2 mi). 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 (1.6 ft) higher than in summer. Tidal velocities passing through constrictions caused by reefs, sand bars and low islands commonly exceed 1–2 m/s (3–6.5 ft/s). Coral reefs in the Red Sea are near Egypt, Saudi Arabia, Israel and Sudan.

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 (1.6 ft) and are governed all by wind. During the summer, NW winds drive surface water south for about four months at a velocity of 15–20 cm/s (6–8 in/s), 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/s (20–23.6 in/s) with a maximum of 1 m/s (3.3 ft) at the mouth of the al-Kharrar Lagoon. However, the range of the north-northeast current along the Saudi coast is 8–29 cm/s (3–11.4 in/s).

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 km/h (4.3 mph) and 12 km/h (7.5 mph), 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 anddirection 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

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 have been:The Red Sea was formed by Arabia being split from Africa by movement of the Red Sea Rift. This split started in the Eocene and accelerated during theOligocene. The sea is still widening, and it is considered that it will become an ocean in time (as proposed in the model of John Tuzo Wilson). In 1949, a deep water survey reported anomalously hot brines in the central portion of the Red Sea. Later work in the 1960s confirmed the presence of hot, 60 °C (140 °F), saline brines and associated metalliferous muds. The hot solutions were emanating from an active subseafloor rift. The high salinity of the waters was not hospitable to living organisms.

• 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 because of much water being locked up in the ice caps.

A number of volcanic islands rise from the center of the sea. Most are dormant, but in 2007 Jabal al-Tair island, in the Bab el Mandeb strait, erupted violently. An eruption among the nearby Zubair islands followed in 2011.

Mineral resources

 Biogenic constituents:In terms of mineral resources the major constituents of the Red Sea sediments are as follows:

Nanofossils, 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.

Living resources

The special biodiversity of the area is recognized by the Egyptian government, who set up the Ras Mohammed National Park in 1983. The rules and regulations governing this area protect local marine life, which has become a major draw for diving enthusiasts.The Red Sea also contains many offshore reefs including several true atolls. Many of the unusual offshore reef formations defy classic (i.e., Darwinian) coral reef classification schemes, and are generally attributed to the high levels of tectonic activity that characterize the area.

Divers and snorkellers should be aware that although most Red Sea species are innocuous, a few are hazardous to humans: see Red Sea species hazardous to humans.

Other marine habitats include sea grass beds, salt pans, mangroves and salt marshes.

Desalination plants

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 andanti-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.

Security

The Red Sea is part of the sea roads between Europe, the Persian Gulf and East Asia, and as such has heavy shipping traffic. Piracy in Somaliaoccurs principally near the area of the Gulf of Aden south of the sea. Government-related bodies with responsibility to police the Red Sea area include the Port Said Port Authority, Suez Canal Authority and Red Sea Ports Authority of Egypt, Jordan Maritime Authority, Israel Port Authority, Saudi Ports Authority and Sea Ports Corporation of Sudan.

Arabian Sea

The Arabian Sea is a region of the Indian Ocean bounded on on the north by Pakistan and Iran, on the south by northeastern Somalia, on the east by India and on the west by the Arabian Peninsula. Some of the ancient names of this body of water include Sindhu Sagar (meaning "Sea of Sindh" in Sanskrit) and Erythraean Sea.

Description

The countries with coastlines on the Arabian Sea are Somalia, Djibouti, Yemen, Oman, Iran, Pakistan, India and the Maldives. There are several large cities on the Arabian Sea coast including Karachi, Gwadar, Pasni, Ormara, Aden, Muscat, Mumbai, Mangalore, Kochi, Keti Bandar, Salalah andDuqm.The Arabian Sea has two important branches — the Gulf of Aden in the southwest, connecting with the Red Sea through the strait of Bab-el-Mandeb; and the Gulf of Oman to the northwest, connecting with the Persian Gulf. There are also the gulfs of Cambay and Kutch on the Indian coast.

Limits

The International Hydrographic Organization defines the limits of the Arabian Sea as follows:

On the West. The Eastern limit of the Gulf of Aden [The meridian of Cape Guardafui (Ras Asir, 51°16'E)].

On the North. A line joining Ràs al Hadd, East point of Arabia (22°32'N) and Ràs Jiyùni (61°43'E) on the coast of Pakistan.

On the South. A line running from the South extremity of Addu Atoll (Maldives), to the Eastern extreme of Ràs Hafun (Africa, 10°26'N).

On the East. The Western limit of the Laccadive Sea [A line running from Sadashivgad Lt. on West Coast of India (14°48′N 74°07′E) to Corah Divh (13°42′N 72°10′E) and thence down the West side of theLaccadive and Maldive Archipelagos to the most Southerly point of Addu Atoll in the Maldives]

Alternative names

Trade routesThe Arabian Sea historically and geographically has had many other different names and it has also been given names by Muslim travelers and European geographers such as: Akhzar Sea^{[citation needed]}, Persian Sea, Sindhu Sagar, Erythraean Sea,^[6] and Sindh Sea.

These routes usually began in the Far East or down river from Madhya Pradesh with transshipment via historic Bharuch (Bharakuccha), traversed past the inhospitable coast of today's Iran then split around Hadhramaut into two streams north into the Gulf of Aden and thence into the Levant, or south into Alexandria via Red Sea ports such as Axum. Each major route involved transhipping to pack animal caravan, travel through desert country and risk of bandits and extortionate tolls by local potentiates.The Arabian Sea has been an important marine trade route since the era of the coastal sailing vessels from possibly as early as the 3rd millennium BCE, certainly the late 2nd millennium BCE through the later days known as the Age of Sail. By the time of Julius Caesar, several well-established combined land-sea trade routes depended upon water transport through the Sea around the rough inland terrain features to its north.

This southern coastal route past the rough country in the southern Arabian peninsula (Yemen and Oman today) was significant, and the EgyptianPharaohs built several shallow canals to service the trade, one more or less along the route of today's Suez canal, and another from the Red Seato the Nile River, both shallow works that were swallowed up by huge sand storms in antiquity. Later the kingdom of Axum arose in Ethiopia to rule a mercantile empire rooted in the trade with Europe via Alexandria.

Major ports

Karachi is also mentioned in the sixteenth century Turkish treatise Mir'ât ül Memâlik (Mirror of Countries, 1557) by the Ottomancaptain Seydi Ali Reis, which is a compilation of sailing directions from the Portuguese island of Diu to Hormuz in the Persian Gulf. It warns sailors about whirlpools and advises them to seek safety in "Kaurashi" harbour if they found themselves drifting dangerously.The Port of Karachi : is Pakistan's largest and busiest seaport, handling about 60% of the nation's cargo (25 million tons per annum). It is located between the Karachi towns of Kiamari and Saddar, close to the main business district and several industrial areas. The geographic position of the port places it in close proximity to major shipping routes such as the Strait of Hormuz. The history of the port is intertwined with that of the city of Karachi. Several ancient ports have been attributed in the area including "Krokola", "Morontobara" (Woman's Harbour) (mentioned by Nearchus), Barbarikon(the Periplus of the Erythraean Sea, and Debal (a city captured by the Muslim general Muhammad bin Qasim in 712 CE). There is a reference to the early existence of the port of Karachi in the "Umdah", by the Arab navigator Sulaiman al Mahri (AD 1511), who mentions "Ras al Karazi" and "Ras Karashi" while describing a route along the coast from Pasni to Ras Karashi.

The gate facing the sea was called "Kharadar" (salt gate), and the gate facing the Lyari River was called "Mithadar" (sweet gate). The modern neighbourhoods around the location of the gates are called Mithadar and Kharadar. Surrounded by mangrove swamps to the east, the sea to the southwest, and the Lyari River to the north, the town was well defended and engaged in a profitable trade with Muscat and Bahrain.

Port of Salalah in Salalah, Oman is also a major port in the area. From a modest start in 1997, the Omani container transhipment port has achieved consistent growth. For a growing number of ships’ crew, the port of Salalah is a welcome sight after an unpleasant and often prolonged encounter with pirates. The Port of Salalah is a key container transhipment hub on the Arabian Sea and is often used as the first port of call for vessels whose crew have just been released from the clutches of Somali pirates following ransom payments for withheld vessels and crew. The port also plays host as a supply base for the visiting warships that provide protective escorts for merchant shipping in the sea lanes. From that dual role has emerged another, one as an intelligence network — both military and civilian — to exchange information on possible pirate sightings and near misses. Also, the International Task Force often uses the port as a base. There is a significant number of warships of all nations coming in and out of the port, which makes it a very safe bubble. The port handled just under 3.5m teu in 2009. The Gwadar Port is a warm-water, deep-sea port situated at Gwadar in Balochistan, Pakistan at the apex of the Arabian Sea and at the entrance of the Persian Gulf, about 460 km west of Karachi and approximately 75 km (47 mi) east of Pakistan's border with Iran. The port is located on the eastern bay of a natural hammerhead-shaped peninsula jutting out into the Arabian Sea from the coastline.

There are also a few Indian ports in the Arabian Sea such as Kandla Port, Nava Sheva, Mumbai Port, Mormugoa and Kochi Port.

Islands

There are several islands in the Arabian Sea, with the largest being Socotra (Yemen), Masirah (Oman), Astola Island (Pakistan) and Andrott (India).

Astola Island, also known as Jezira Haft Talar  or 'Island of the Seven Hills', is a small, uninhabited island in the northern tip of the Arabian Sea in Pakistan's territorial waters. It is a popular eco-tourismdestination in the region.Overnight tourists camp on the island and bring their own provisions. Camping, fishing and scuba-diving expeditions are popular. It is also a site for observing turtle breeding. Endangered animals such as theGreen turtle (Chelonia mydas) and the Hawksbill turtle (Eretmochelys imbracata) nest on the beach at the foot of the cliffs. The island is also a very important area for endemic reptiles such as the Astola Viper (Echis carinatus astolae).

Masirah  is an island off the East coast of Oman. The main industries here are fishing and traditional textile manufacturing. Formerly, traditional ship building was important. The rugged terrain of the island and surrounding rough coastline has led to the appearance of many wrecked dhows on the beaches of the island, most of them well preserved by the salt water and intense heat. The ocean bottom environment surrounding Masirah is hostile as the majority of the area is covered in either sand or hard rock. Despite the poor quality ocean bottom, the area is very productive with marine fisheries, and any hard objects (barrels, engines) are immediately colonized by local fauna.Socotra , also spelled Soqotra, is the largest island, being part of a small archipelago of four islands. It lies some 240 kilometres (150 mi) east of the Horn of Africa and 380 kilometres (240 mi) south of the Arabian Peninsula. The island is very isolated and through the process of speciation, a third of its plant life is found nowhere else on the planet. It has been described as the most alien-looking place on Earth.