Topography and ecosystems
The UAE is largely an arid land with vast sand deserts, but is also characterised by sand dunes, oases, rock mountains, valleys, marshes and mangroves and salt plains.
The oases are mostly of date palms; most oases are located in the emirate of Abu Dhabi.
Along the eastern borders are the Hajjar Mountains that run north-south. These mountains are complemented by valleys (called wadis in Arabic). The wadis are usually dry. However, in cooler months when it rains, they flourish with brooks and pools.
Mangroves (called qurms in Arabic) form an integral part of the marine ecosystem.
Salt plains (called sabkhas in Arabic) are also a common feature. The present-day sabkha started to form some 4000 years ago.
The UAE's natural environment is diverse with three major varieties of ecosystems:
- desert ecosystem
- mountain ecosystem
- coastal and marine ecosystem.
Desert is the dominating landscape, stretching from the southern coast of Arabian Gulf to the uninhabited sands of the Empty Quarter (Rub Al Khali). To the east is the gravel plains bordering the Hajjar Mountains.
Hajjar's rugged mountains rise sharply to an elevation of 2000 metres. Wadis or dry riverbeds open out onto fertile plains.
Coastal and marine ecosystem
The UAE's seas are home to a variety of fish, invertebrates and other marine animals. The southwest waters of Abu Dhabi and Marawah Marine Biosphere Reserve in Abu Dhabi, Jebel Ali in Dubai and Sir Bu Na'air Island and Khor Kalba in Sharjah are recognised by the UAE for their rich and unique environmental biodiversity and are of global biological and ecological importance. The marine habitat protects beaches from coastal erosion and plays a role in climate change mitigation.
Natural habitats of marine organisms are governed mostly by the type of surface, tides, water current, degree of wave exposure, temperature and salinity.
The marine life of the UAE is rich in fish, plants and corals. Over 500 different species of fish inhabit the Gulf waters, with many more existing in the Indian Ocean.
The Arabian Gulf is blessed with large populations of dugongs, dolphins (eight species) and marine turtles. The green turtle (Chelonia mydas) is the most common and feeds on the extensive sea grass beds found in shallow waters. Both green and hawksbill (Eretmochelys imbricata) turtles are known to nest on the beaches of UAE's main coast and islands.
Coral reefs and mangrove creeks are habitats for many marine creatures. These areas are important fish breeding grounds and feeding areas and they protect the shores from coastal erosion.
Damage to coastal developments, fishing nets, anchors and ignorant divers cause destruction of these areas. Coral reefs are sensitive to their environment. They take decades to regrow.
Dominant marine life forms in the UAE coasts include fish, marine mammals and marine reptiles.
At the entrance to the Arabian Gulf, the constriction and resultant strong currents of the Strait of Hormuz, influence the distribution of many species.
Marine mammals are relatively common in the UAE's waters and include a great diversity. The two groups of marine mammals that are represented here are the whales and dolphins of the order Cetacea, and dugong of the order Sirenia.
These include sea turtles and sea snakes.
Of the seven recognised species of marine turtles in the world, four live in the waters of the UAE. They are:
- The green turtle (Chelonia mydas)
- The hawksbill turtle (Eretmochelys imbricata)
- The loggerhead turtle (Caretta caretta)
- The huge leatherback turtle (Dermochelys coriacea).
Sea Snakes are found in the UAE's seas. There are at least seven species, all of which belong to one family, the Hydrophiidae. They are excellent swimmers and the laterally flattened tail makes them easily recognisable and distinguishes them from eels.
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The UAE's coasts
The UAE has two coastlines. The longer coast, at over 700 kilometres, excluding islands, faces in a north to north-westerly direction into the southern Arabian Gulf whilst the other, much shorter, coast, approximately 70 kilometres long, faces eastwards into the Gulf of Oman.
Much of the Arabian Gulf coastline is low-lying, flat and bordered by shallow water. While the coast of Gulf of Oman is rugged and eroding, with a higher proportion of hard rock.
The differences in climate along the two coasts has led to assemblages of marine organisms that are somewhat different, although both are of Indian Ocean origin.