Coral reefs fringe the entire Red Sea coastline and offshore islands, with several distinct areas of similar habitats and species composition: the Gulf of Aqaba in the north; the northern-central section from south of the Gulf of Aqaba to Jeddah; and the central-southern region from Jeddah to the Yemen border, including the Farasan Bank and Islands. The northern-central area has an almost continuous coral reef tract with many reef types: mainland and island fringing reefs; various forms of patch reef; coral pinnacles; and ribbon barrier reefs. Reefs fringe the mainland and often into the entrances and sides of sharms (lagoon-like inlets). Circular to elongate patch reefs are common in offshore waters less than 50m depth. Pinnacles (individual corals and coral ‘bommies’ surrounded by sand) occur in shallow waters (less than 10m), particularly in the Al-Wajh Bank and Tiran areas. Barrier reefs composed of platform and ‘ribbon’ reef structures occur further offshore on the ‘continental’ edge, where depths drop from 50m to more than 200m. The centralsouthern area is unique in having atoll-like or ‘tower’ reefs along the shelf edge and the outer Farasan Bank. Further south, the reefs are less well developed along the mainland coast because of high levels of fine sediments, however, complex reef structures developed further offshore on the Farasan Bank and islands.

The reefs are mostly small pinnacles or outcrops, and patch reefs between Ras Al-Mishab Saffaniyah and Abu Ali, and between Abu Ali and Ras Tanura, and as fringing reefs around the offshore islands of Karan, Kurayn, Jana and Jurayd.

The Red Sea and Arabian Gulf exhibit markedly different bio-physical conditions, with the Arabian Gulf exhibiting more extreme changes in water temperature, in part related to the comparatively shallow nature of the Gulf, in particular close to shores (over 25% of the Gulf is only 5 - 10 m deep; MEPA/IUCN 1992a). Species of corals appear more tolerant than their counterparts in the Red Sea, and up to a critical point are able to withstand environmental extremes that would normally kill corals in most other reef areas outright (Sheppard & Sheppard 1991). Waters and coastal habitats of the Gulf were adversely affected by massive oil spills during the Gulf War, with different habitats and biota being differentially affected (Krupp et al. 1994). Coral reefs were little affected (Vogt 1996), exhibiting high cover in most sites surveyed subsequently. More severe effects to reefs occurred in 1998, when elevated sea temperatures caused major death of shallow water corals in some areas (Vogt & Al Shaikh in press).

The Red Sea coast and islands support a variety of coastal and marine habitats, related largely to oceanographic regime, degree of exposure, and topographic features, particularly the distribution of suitable antecedent topography for development of coral reefs, mangrove stands and seagrass beds. The area has a complex tectonic history of uplift and subsidence, related to the rift development of the Red Sea from the movements of the Arabian and African tectonic plates. The present series of living coral reefs are the latest in a chronological sequence of raised (uplifted) and submerged reefs that have developed at various times over the past several hundred millenia. In many cases the present reefs are developed on earlier reef structures. Detailed descriptions of the geology, physical environment, climate, hydrology, oceanography and habitats of the Red Sea and wider Arabian Region are presented by Fishelson (1971), Mergner (1971), Scheer (1971), Ormond et al. (1984a), Edwards & Head (1987), Crossland et al. 1987, IUCN/UNEP 1988, Benthoux (1988), Sheppard & Sheppard (1985, 1991), Behairy et al. (1992) and Sheppard et al. (1992).

The Saudi Arabian Red Sea coast is divisible into several relatively homogeneous areas in terms of the variety and distribution of coastal and marine habitats and reefs: the Gulf of Aqaba in the north, the northern-central section from immediately south of the Gulf of Aqaba to Jeddah, and the central-southern region from south of Jeddah to the Yemen border and including the Farasan Bank and Islands.

The Gulf of Aqaba is deep and relatively narrow, and is characterized by its geographical isolation and the number of species that are either restricted to or from the area, including several species of reef-building corals and fish. The extreme north of the Gulf contains species presently known from nowhere else in the Red Sea (MEPA 1987). Cool sea temperatures and a dispersal 'bottle-neck' into and out of the Straits of Tiran may be important factors in these species distributions. Reefs are typically narrow, fringing the steep mainland coast.

The northern-central Red Sea has a much higher diversity of reef and coastal habitat types than the Gulf of Aqaba, including large expanses of coastal marshes (sabkha), seagrasses, macro-algae and mangrove stands, and reefs fringing both the mainland and islands and offshore patch and barrier reefs. The area is renowned for the presence of the Al Wajh Bank, a large, relatively shallow area bordered by a barrier reef system on its seaward edge and incorporating many islands and reefs. The Bank is unique in several respects and is the current focus of marine protected areas planning by the NCWCD. With the exception of reefs in the vicinity of coastal towns and cities, most remain in good condition (NCWCD-JICA 2000, DeVantier et al. in press).

The central-southern area, including the Outer Farasan Bank and islands, has a different bio-physical and geomorphological character to the northern area and Gulf of Aqaba. The area contains species which are more suited to more turbid sediment-loaded waters which occur here because of terrigenous input and water mixing across the wide shallow coastal shelf. The highest sea temperatures are found in this zone and coral development is restricted. The Farasan Islands and surrounding waters and reefs have been designated as a major protected area.

Thus coral reefs fringe much of the entire length of the Saudi Arabian Red Sea coastline and the offshore islands (Fig. 1), and are generally in good condition with the exception of those near Jeddah and Yanbu (PERSGA 1998). Five areas in particular have been noted for their coral reefs: the Tiran Islands, the Al Wajh Bank, the reefs north of Yanbu, between Obhur and Thuwal north of Jeddah, and the outer Farasan Bank (MEPA/IUCN 1992b). In the Arabian Gulf (Fig. 2), the reefs mostly appear as small pinnacles or outcrops, and as patch reefs between Ras Al-Mishab Saffaniyah and Abu Ali, and between Abu Ali and Ras Tanura, and as fringing reefs around the offshore islands (MEPA/IUCN 1992a).

The near-continuous coral reef tract of the Red Sea has high local, regional and global conservation significance. With the exception of reefs in the immediate vicinity of coastal cities and towns (particularly Jeddah and Yanbu), these reefs generally have low levels of human use and impact. The region includes most of the world's major reef types, including mainland fringing reefs, island fringing reefs, platform patch reefs, 'pinnacles' and barrier reefs. Reefs are often developed in sharms along the mainland coast, a characteristic reef-form largely restricted to the Red Sea. While most reefs are actively accretional, levels of reef development vary widely, from subsurface patch reefs with no reef flat (mostly in the Al-Wajh Bank and southern area), to narrow ‘contour’ fringing reefs with reef flats < 30 m wide (in the Gulf of Aqaba) to large platform and barrier reefs with reef flats often > 100 m wide, to tower reefs similar to atolls (on the Farasan Bank). These reef types support coral communities with highly variable levels of living and dead coral cover, species diversity and unique community composition, including species endemic to the region and others presently undescribed. The communities also support other reef-associated species of high conservation value and/or economic importance.

Red Sea: The central-northern area from north of Jeddah to Haql in the Gulf of Aqaba supports a near-continuous coral reef tract composed of a wide range of reef types. The area supports relatively complex reef geomorphology, being comprised of mainland and island fringing reefs, various forms of patch reef, coral pinnacles and ‘ribbon’ barrier reefs (Ormond et al. 1984a provide a comprehensive review of the geomorphology and distribution of these reef types).

Mainland fringing reefs are distributed along much of the coastline, and are often developed in the entrances and sides of sharms, a characteristic reef-form largely restricted to the Red Sea (Ormond et al. 1984c). Extensive mainland fringing reefs occur around Rabigh, Ras Baridi, Umluj, Al-Wajh-Duba and in the Gulf of Aqaba, the latter often being narrow (< 30 m width), developed as ‘contours’ on the relatively steep sub-littoral topography (Fishelson 1980). Island fringing reefs are commonly developed in the Tiran area and from Duba - Al-Wajh Bank - Umluj.

Circular / elongate patch reefs are also widespread in offshore waters (< 50 m depth). Some patch reefs support sand-coral islands (cays), while others are submerged and resemble coral carpets (sensu Riegl & Piller 1999). Both forms are common in the Al-Wajh Bank and south from Umluj - Rabigh. ‘Reticulate’ patch reefs (‘labyrinths / mazes’ sensu Ormond et al. 1984a), composed of interconnected networks of reef matrix separated by sand, and forming intricate reticulate patterns, are particularly well developed in shallow waters (< 10 m depth) of the Tiran area and southern Al-Wajh Bank. Pinnacles (individual corals and coral ‘bommies’ surrounded by sand) are present in shallow waters (< 10 m depth), particularly in the Al-Wajh Bank and Tiran areas (DeVantier et al. in press).

Barrier reefs composed of platform and ‘ribbon’ reef structures are developed further offshore on the edge of the ‘continental’ slope, where water depths increase from < 50 m to > 200 m. The best-developed barrier reef system occurs along the seaward margin of the Al-Wajh Bank. The barrier is formed of a continuous line of reefs stretching for ca. 100 km and separated by several narrow (< 200 m width) channels (Ormond et al. 1984a, DeVantier et al. in press). Another barrier reef system of different gross geomorphological structure, the ‘Little Barrier Reef’, occurs further south near Yanbu (Ormond et al. 1984a, Sheppard & Sheppard 1985). The central-northern Saudi Arabian Red Sea does not support atoll-like or ‘tower’ reefs, more characteristic of southern areas and the outer Farasan Bank (Ormond et al. 1984a).

To the south of Jeddah, reefs become less well developed along the mainland coast, as differences in topographic features, sediment and turbidity tend to restrict coastal reef growth progressively towards the Yemen border (Price et al. 1998). Further offshore however, complex reef structures are developed on the Farasan Bank and islands (Ormond et al. 1984a), including tower reefs, similar in gross geomorphology to atolls, rare or absent in other areas of the Saudi Arabian Red Sea.

Levels of reef accretion among the various reef types range from small (< 1 ha) subsurface patch reefs - carpets with no reef flat to narrow fringing reefs with reef flats < 50 m wide to large fringing, platform and barrier reefs with reef flats often > 100 m wide.

Arabian Gulf: By comparison with the extensive development and large extent of the Red Sea reefs, the Saudi Arabian portion of the Arabian Gulf supports minimal area of coral reefs and coral communities, being confined to small fringing reefs around Abu Ali, and several offshore patch reefs, most of which support small coral islands (cays – e.g. Jana and Karan Islands). Despite their small geographic scale, these reefs are notable for being developed in extreme environmental conditions inimical to coral growth in most reef areas globally (Coles 1988, Coles & Fadlallah 1991, Fadlallah et al. 1993). The reefs are known to support < 100 species of stony corals and ca. 600 spp. of reef-associated fishes. These reefs are already protected within the Jubail Nature Sanctuary marine protected area, established following the 1991 Gulf War (Krupp et al. 1994). These reefs survived the effects of the Gulf War oil spills, but were affected to greater or lesser degree by bleaching in 1998 (Vogt 1996, Vogt & Al Shaikh 2000).

The coral reefs along the 1800 km Red Sea coastline are generally in good condition, with high living coral cover, often exceeding 50%, and healthy stocks of key fish and invertebrate species (except near major cities). Few areas have been surveyed, but the best reefs in 2002, were on the Wajh Bank (average 40% cover at 5 m). Jeddah reefs had 20% cover at 5 m, and the reefs off Farasan Island had 28% at 5 m. Jeddah reefs are influenced by the growing city of 2.2 million.

Corals on The Gulf mainland are mostly limited to small pinnacles or outcrops, and patch reefs between Ras Al-Mishab Saffaniyah and Abu Ali, and between Abu Ali and Ras Tanura. The most developed and most diverse reefs are around 6 offshore islands, particularly Jana and Karan.