Coral Reefs of the Gulf of Aqaba and the Red Sea in the Kingdom of Saudi Arabia

Description

This proposal represents a key constituent of Saudi Arabia’s intent and commitment to conserve the Red Sea and the Gulf of Aqaba for their globally significant biodiversity as well as their vital national role in achieving the sustainable development targets of the country as part of its ambitious 2030 Vision.  

The Red Sea is the northernmost tropical sea on Earth and is semi-enclosed, being linked with both the Mediterranean Sea and Arabian Sea through two narrow corridors, the Suez Channel and Bab Al Mandab Strait, respectively. Although known to many for tourism of its spectacular and truly wondrous coral reefs, the Red Sea is becoming increasingly acknowledged as a unique place to study coral ecosystems.

The Gulf of Aqaba (Khalij al-‘Aqabah in Arabic) in Saudi Arabia is around 200 km long, 14–26 km wide and around 1,700 m deep. It is located between the Sinai Peninsula and the north-westernmost part of Saudi Arabia, and is separated from the northern Red Sea by a shallow sill (240 m) at the Strait of Tiran. Salinity is very high, about 40.2 to >41‰. The Gulf of Aqaba is much narrower than the other regions of the Red Sea and is characterized by steeper and more precipitous topography along its flanks. It hosts unique coral reefs and very rich marine biodiversity and offers various ecosystem services making it one of the most socially and economically important areas of the Red Sea.

Justification of Outstanding Universal Value

Some of the most temperature-resilient corals live in the Red Sea, and the northern Red Sea might constitute a refuge for corals for decades to come – making it the largest laboratory in the world to study coral adaptation to climate change and a beacon of hope in such desperate times, when an estimated 30% of global reef cover has already been lost to climate change-driven coral bleaching.

Compared to the coral reefs of the central and southern regions of the Red Sea which have historically known mass bleaching events when exposed to heat stress, those of the northern region, in particular those in the Gulf of Aqaba, were found to be exceptionally resistant to heat waves and have not experienced mass bleaching. The thermal tolerance of the Red Sea and the Gulf of Aqaba corals proven by historical bleaching records was further verified and confirmed though various experimental investigations. According to many studies, the thermal tolerance limits of corals from the Northern Red Sea can exceptionally reach records of >5℃ above their summer maxima, which are lethal for corals elsewhere.

Coral reef scientists attribute these elevated thresholds to historical selection, as corals passed through the warmer Southern Red Sea during re-colonization from the Arabian Sea. These thermal-resistant corals have been found nowhere else on the planet, constituting the only global repository of this form of marine life.

Based on these findings, coral reefs of the Red Sea and the Gulf of Aqaba can be considered to be unique, since they represent an open sky laboratory to investigate coral resilience to climate change and a coral gene bank that provides a measure of resilience to the coral reefs of the world in the event of future mass mortalities caused by climate change.

The Red Sea and the Gulf of Aqaba host more than 265 species of corals, which form mainly fringing reefs which offer food and shelter to hundreds of vertebrate and invertebrate species, including endemic and endangered taxa that require increasing efforts of conservation in the region.

Given all the properties described above, the Red Sea and the Gulf of Aqaba can be considered as meeting World Heritage Site nomination requirements. An on-going process to protect the Saudi waters in the Red Sea and the Gulf of Aqaba has already been initiated to conserve the unique coral reefs in this region and their associated fauna, and to sustain their ecosystem services and socio-economic roles.

Criterion (viii): A major geomorphic feature of the coastal Red Sea region is represented by Pleistocene raised marine terraces that occur on both sides of the Gulf of Aqaba. Those bordering the Saudi Arabian sector have received little attention thus far and are comparatively lesser known than their counterparts in the Sinai sector and the Red Sea. As is the rule in the Red Sea region, the best developed marine terrace system is reefal and pertains to the last interglacial period, although older Pleistocene terraces also occur. All such deposits are very fossiliferous, and most carbonates are relatively unaltered, providing suitable material for geochronological processes. In some respects, the MIS5e deposits are unique, reflecting the structurally controlled bedrock geology and the area topography.

During the 2020 research cruise of OceanXplorer, a Saudi expedition aimed at exploring and further detailing the deep seabed offshore Saudi Arabia, a complex of brine pools was discovered in the Gulf of Aqaba at 1,770 m water depth. These pools, named NEOM Brine Pools, are the first ones discovered outside the Red Sea proper. Given that these pools were found in a location that had never been reported before, a series of in situ measurements and samples (water, surficial sediment samples, and cores) were collected for the purposes of characterizing the overall physical setting of the pools, their sedimentology, chemistry, and biology. The data were used to determine if NEOM Brine Pools are representative of the established categories of Red Sea brine pools, or if they present a new category. A defining feature that separates the NEOM pools from previous Red Sea discoveries is that they are located only 2 km from the coast, significantly closer than the next most shore proximal Thuwal Seep, situated 25 km offshore. Situated as such, the NEOM brine pools are positioned to receive sediments shed from the coastal zone and therefore have the unique potential to archive historical tsunamis, flash floods, and seismicity in the Gulf of Aqaba. They are located at the bathyal plain of the Aragonese Deep. This basin is conspicuous in being >800 m deeper than the Gulf’s average, and comparable in depth to much of the Red Sea axial trough. Major strike slip faults occur along both sides of the Aragonese Deep. The east side is confined by the Arona fault and the Aragonese fault bounds to the west. This fault geometry has a large extensional component and the Deep is considered a true pull-apart basin, the only such occurrence in the Gulf of Aqaba.

Criterion (ix): As stated above, the thermal resistance of the Red Sea and the Gulf of Aqaba corals, which has been verified by various scientific studies, argues in favour of a clear evolutionary process to adapt to climate change found nowhere else on the planet. Based on the findings of the experimental investigations conducted so far on this topic, the corals of this region showed resistance to thermal limits that are lethal to the same species or their congeneric species occurring in other regions of the globe, even with those as close as the southern areas of the Red Sea. Although preliminary studies have already identified the genetic factors/genes explaining this exceptional thermal resistance, further and deeper studies are still needed to define the physiological mechanisms enabling these adaptation properties.

This means these are corals that should not be lost to humanity and must be preserved in perpetuity through mechanisms such as the World Heritage Convention. The conservation of the coral reefs of the Red Sea and the Gulf of Aqaba is the key solution to increase the knowledge on the resistance of corals to climate change, which will certainly help to adapt solutions for the conservation of coral reefs in other parts of the world. This will also enhance the conservation and regeneration of these exceptional ecosystems and their associated fauna in the region.

Apart from that, the high endemism in the northern Red Sea is another indication of a local evolutionary process. Although the local biodiversity is not yet fully described, many fish and shellfish species are reported to be endemic to the northern Red Sea and/or the Gulf of Aqaba. These include -among others- the Longnostril podge Pseudogramma megamycter, Red Sea deepwater cardinalfish Epigonus marisrubri, Duskytail chromis Chromis pelloura, Broadstriped anthias Pseudanthias taeniatus, Pale dottyback Pseudochromis pesi, Randall’s dragonet Diplogrammus randalli, Bluespotted shrimpgoby Cryptocentrus caeruleopunctatus, Randall’s shrimpgoby Psilogobius randalli, Barrall’s dwarfgoby Trimma barralli, and Bittersweet clam Glycymeris livida.

Some of these taxa are listed in the IUCN Red List of Endangered Species such as the vulnerable Pseudochromis pesi, and hence require increasing efforts for their conservation. Most of these endemic species are associated with the coral reef ecosystems represneted in the region; their connectivity and distribution of larval sources, larval sinks, breeding areas, reproductive activity patterns, and migration patterns still need to be studied. The nomination of these coral reefs as a WHS will help to protect these endemic species and conserve them for future generations.

Criterion (x): The Red Sea and the Gulf of Aqaba are unique and diverse aquatic ecosystems and are important habitats for one of the richest coral reefs in the world. They are home to over 265 species of coral and some 800 species of fish. Most importantly, the area supports the world’s only genetic assembly of climate-resistant corals. These corals cannot be preserved easily in laboratories, where genetic mixing and space limitations may inhibit the very reason for their value: climate-resistance. For this, an in-situ conservation process of adequate proportions is required, and for this we submit this site for consideration as a WHS.

A wide variety of coral reefs occurs in the Red Sea and the Gulf of Aqaba off the coast of Saudi Arabia, including the families Cyphastrea, Millepora, Sarcophyton, Caulastrea, Goniopora, Montipora, Stylophora, Galaxea, Favites, Capnella, Amphiprion, Goniastrea, Leptastrea, Lobophyllia, Favia, Phymastrea, Acropora, Dipsastraea, Fungia, Pocillopora, Pavona, Porites, Platygyra, Leptoseris, Echinopora and numerous species of crustaceans, molluscs, echinoderms, sponges, and other invertebrates.

Notable fish species found in the area include the families Scorpaenidae, Scaridae, Serranidae, Acanthuridae, Pomacanthidae, and Chaetodontidae. Fourteen elasmobranchs (8 shark and 6 ray species) have been recorded in the Saudi waters including the Ocellated eagle ray (Aetobatus ocellatus), Pink whipray (Himantura fai), Reticulate whipray (H. uarnak), Cowtail stingray (Pastinachus sephen), Bluespotted ribbontail ray (Taeniura lymma), Round ribbontail ray (Taeniurops meveni), Pelagic thresher (Alopias pelagicus), Grey reef shark (Carcharhinus amblyrhynchos), Spinner shark (C. brevipinna), Sandbar shark (C. plumbeus), Tiger shark (Galeocerdo cuvier), Whale shark (Rhincodon typus), Whitetip reef shark (Triaenodon obesus) and Bigeye houndshark (Iago omanensis) are likely to be the most abundant elasmobranch species in the region. The critically endangered Halavi guitarfish (Glaucostegus halavi) has been discovered in bay systems along the Saudi Arabian coastline of the Red Sea. Most of the elasmobranch species are listed as “vulnerable”, “endangered”, and “near threatened” in the IUCN Red List of Endangered Species.

Marine mammals (cetaceans) recorded in the area include the Bryde's whale (Balaenoptera edeni), Humpback whale (Megaptera novaeangliae), False killer whale (Pseudorca crassidens), Risso’s dolphin (Grampus griseus), Indo-Pacific bottlenose dolphin (Tursiops aduncus), Common bottlenose dolphin (Tursiops truncatus), Pantropical spotted dolphin (Stenella attenuata), and Spinner dolphin (Stenella longirostris). Endangered dugongs (Dugong dugon) are also found here. The Green (Chelonia mydas) and Hawksbill (Eretmochelys imbricata) turtles are also residents of the area, with Green turtles (C. mydas) being the marine reptile most frequently observed. Sea turtles are found in association with reef structures or seagrass beds near the coast. Green turtles are most often seen in and around seagrass beds, which provide most of their diet. Hawksbill turtles are found in association with coral reef structures, in line with their dietary preference for sponges and soft corals. Many of the abovementioned megafauna species are endangered and require more efforts to conserve them.

In addition, the Red Sea and the Gulf of Aqaba are known to be home for some spring migratory seabird species such as the Black-crowned night heron (Nycticorax nycticorax), Grey heron (Ardea cinerea), Common tern (Sterna hirundo), and White-winged tern (Chlidonias leucopterus). Other non-breeding seabird species are known to occur in the offshore areas between spring and autumn. These include the Scopoli's shearwater (Calonectris diomedea), Wedge-tailed shearwater (Puffinus pacificus), Sooty shearwater (P. griseus), Brown booby (Sula leucogaster), Pomarine jaeger (Stercorarius pomarinus), Parasitic jaeger (S. parasiticus), Long-tailed skua (S. longicaudus), White-eyed gull (Larus leucophthalmus), White-cheeked tern (Sterna repressa) and Bridled tern (S. anaethetus), as well as vagrant pelagic species.

Statements of authenticity and/or integrity

Coral reefs in the Red Sea and the Gulf of Aqaba provide various natural resources to locals, in particular to fishers who depend on these valuable ecosystems for employment and food provision. Local fishers target various edible species including Spanish Mackerel, Jacks, Groupers, Emperors, Snappers, Barracudas, Tunas, and several shellfish species. Apart from that, the Saudi coast in the Gulf of Aqaba hosts only one coastal city (Haql City), with almost no industrial and agricultural complexes that might affect the marine environment.

The limited natural stresses that occur in the Saudi coastline are attributed to human uses such as small coastal developments, fishing, and tourism. However, these disturbances, which result from actions prior to the site’s nomination for inscription on the World Heritage List, are not so severe as to irreparably compromise its ecological integrity.

It is worth mentioning that the coast of the Gulf of Aqaba is embedded within the geographic extent of NEOM, one of the mega-developmental projects in the Kingdom of Saudi Arabia which aims at investing in the natural environment (both marine and terrestrial) in a way that fully respects the conservation of habitats and wildlife. Some touristic projects are being developed in selected coastal and land areas, but no large-scale industrial or human settlements are planned to be established within the proposed area of nomination to the World Heritage List. These touristic projects have been developed taking into account the best environmental practices that do not harm the natural habitats, in particular the coral reefs of the Gulf of Aqaba, and in coordination with local authorities including the National Center for Wildlife.  

The ecological integrity of the Red Sea and the Gulf of Aqaba is reinforced by the relatively large size and current good conservation status of the entire area.

At the ecosystem level, most habitats and species groups in the area are unusually resilient in their ability to recover from disturbance and to withstand persistent stresses. The area is largely intact and provides a great diversity of marine ecological, physical, and chemical processes from the coast to the deep abyssal waters, allowing the major interdependent elements to exist in their natural relationships. This has been already scientifically proven with the corals of the Red Sea and the Gulf of Aqaba which have shown a greater capacity than corals in other regions to adapt to rising temperatures associated with global climate change. In addition, the coral reefs in the area represent a refuge for highly diversified fish and shellfish communities including various commercially important species. Thus, these valuable habitats are likely to exert a spillover effect on the surrounding regions of the Red Sea contributing therefore to repopulate the neighbouring fishing grounds and to sustain the fisheries sector in the region. This argues in favour of the need to continuously enhance the conservation of the Red Sea and the Gulf of Aqaba and declare it as a World Heritage Site.

The general law and environmental strategy in the Kingdom of Saudi Arabia has enhanced the protection of both terrestrial and marine habitats and it is easy under these regulations to establish a conservation program for coral reefs to protect their unique value. Within this context, the Kingdom of Saudi Arabia inaugurated in 2021 the Saudi Green Initiative (SGI) which unites environmental protection, energy transition and sustainability programs. The main aims of SGI are offsetting and reducing emissions, increasing the Kingdom’s use of clean energy, and addressing climate change. Coral reef conservation and the designation of 30% of the Saudi territorial areas (both marine and terrestrial, focused on biodiversity hotspots and representing all the country’s ecosystem types) as protected areas are among the priorities and ultimate goals of the SGI. New regulations have been recently established for the protection of coral reefs and sea turtles in the Red Sea. These policies and measures provide effective instruments to maintain the integrity of the Gulf of Aqaba’s coral reefs.

Comparison with other similar properties

The coral reefs in the Red Sea and the Gulf of Aqaba are similar to those in the Great Barrier Reef (Australia) in terms of sea forms diversity, rich biodiversity, and occurrence of species of conservation significance. Both areas provide important environmental and socio-economic values. The coral reefs of the Red Sea and the Gulf of Aqaba also share certain common characteristics with those in other Red Sea regions such as Ra’s Muhammad in Egypt, and Sanganeb/Dungonab in Sudan, and also with other World Heritage Sites and marine protected areas in the Indian Ocean.

However, it is worth noting that the coral reefs of the Red Sea and the Gulf of Aqaba differ from those of the other regions by their exceptional ability to resist and adapt to climate change and global warming. This natural ecological and biological value gives more importance to the Red Sea coral reefs and make them worth nominating as a World Heritage Site. In addition, the Red Sea and the Gulf of Aqaba have additional properties that make them unique on a world stage: These include the closeness of the deep areas from the coast which also host rare deep-sea coral species (and other deep-sea taxa), brine pools, sharp drop-offs, arid climate, and lack of terrestrial runoff. All these properties show the uniqueness of the Red Sea and the Gulf of Aqaba and their ecosystems which need to be conserved to future generations and for humanity.