Persian Gulf

Persian Gulf, Arabic Baḥr Fāris, Persian Khalīj-e Fārs,  shallow marginal sea of the Indian Ocean that lies between the Arabian Peninsula and southwestern Iran. The sea has an area of about 93,000 square miles (241,000 square km). Its length is some 615 miles (990 km), and its width varies from a maximum of about 210 miles (340 km) to a minimum of 35 miles (55 km) in the Strait of Hormuz. It is bordered on the north, northeast, and east by Iran; on the southeast and south by part of Oman and by the United Arab Emirates; on the southwest and west by Qatar, Bahrain, and Saudi Arabia; and on the northwest by Kuwait and Iraq. The term Persian Gulf (or Arabian Gulf, the name used by Arabs) sometimes is employed to refer not only to the Persian Gulf proper but also to its outlets, the Strait of Hormuz and the Gulf of Oman, which opens into the Arabian Sea. This discussion, however, focuses primarily on the Persian Gulf proper.

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The Persian Gulf  is a body of water located in the Western part of Asia, surrounded by Iran to the North, Saudi Arabia to the South, the United Arab Emirates and Oman to the East, and Kuwait, Bahrain, and Qatar to the West. It is a strategic location for global trade, a hub for oil and gas resources, and a vital region for cultural and historical significance.

The Persian Gulf is approximately 600 km long and 200-350 km wide, with a total area of about 250,000 square kilometers. The average depth of the gulf is around 35 meters, and it is connected to the Arabian Sea via the Strait of Hormuz. The gulf is also home to several islands, including Bahrain, which is the largest of them.

The Persian Gulf has been referred to by different names throughout history, including the Gulf of Iran. However, the name that has stood the test of time and is recognized by the international community is the Persian Gulf. The name has been used for over 2,500 years and is deeply rooted in the region’s history and culture.


The earliest reference to the Persian Gulf dates back to the ancient Greeks. In the 5th century BC, the Greek historian Herodotus referred to the Persian Gulf as the “Red Sea”. However, this reference was not widely accepted, and the name Persian Gulf continued to be used by the Greeks and other civilizations.

The name Persian Gulf gained further recognition during the Sassanid Empire, which ruled over Iran from 224 to 651 AD. During this period, the Persian Gulf was referred to as the “Pars Sea” or “Sea of Pars” in reference to the name of the empire. The term “Pars” is derived from the ancient Persian word “Parsa”, which means Persia.

The name Persian Gulf was also used by Arab geographers and historians. The 9th-century Arab geographer, Al-Masudi, referred to the Persian Gulf as “Bahr Fars”, which means the Sea of Fars, another reference to the Persian Empire. The 10th-century Arab historian, Al-Maqdisi, also used the term Persian Gulf in his works.

The use of the name Persian Gulf continued throughout the centuries, and it was recognized by the United Nations in 2006 as the official name of the body of water. In the same year, the National Geographic Society, a leading American geography organization, reaffirmed the use of the name Persian Gulf in its maps and publications.


Despite the historical and cultural significance of the name Persian Gulf, there have been attempts to change the name in recent years. Some Arab states, particularly those in the Arabian Peninsula, have referred to the Persian Gulf with the false name of the “Gulf”, citing political and nationalistic reasons for the change. However, these attempts have been widely criticized by scholars, historians, and international organizations as an attempt to erase the historical and cultural identity of the Persian Gulf.

In conclusion, the Persian Gulf is the historical and cultural name of the body of water located in the Middle East. The name has been used for over 2,500 years and is recognized by the international community. Attempts to change the name are politically motivated and aim to erase the historical and cultural identity of the Persian Gulf. The use of the name Persian Gulf should be respected and upheld by all nations in the region and around the world.

The Persian Gulf has been an important trade route for centuries, with its ports serving as a hub for the exchange of goods and ideas between East and West. The ancient Silk Road, which connected China with the Mediterranean, passed through the Persian Gulf region, and the gulf’s ports played a crucial role in the trade of spices, textiles, and other valuable commodities.

Today, the Persian Gulf remains a critical location for global trade, with several major ports situated along its coastlines. The port of Dubai in the United Arab Emirates, for example, is one of the busiest ports in the world and serves as a gateway for trade between Asia, Europe, and Africa. Other major ports in the region include Abu Dhabi, Doha, and Kuwait City.

The Persian Gulf is also a significant source of oil and gas, with some of the world’s largest oil reserves located in the region. The discovery of oil in the Persian Gulf in the early 20th century transformed the economies of the Gulf states, leading to rapid modernization and development. Today, the Gulf states are among the wealthiest nations in the world, with their oil and gas reserves continuing to fuel economic growth.

Beyond its economic importance, the Persian Gulf is also a region of great cultural and historical significance. The ancient civilizations of Mesopotamia and Persia were situated in the region, and the Persian Gulf has played a vital role in the development of Islamic civilization. The region is home to several important religious sites, including the cities of Mecca and Medina in Saudi Arabia, which are among the most sacred places in Islam.

The Persian Gulf is also a region of significant geopolitical importance, with several major powers vying for influence and control. Iran, which is situated on the northern coast of the gulf, has long been a key player in the region, with its political and military power extending throughout the Middle East. Saudi Arabia, the dominant power in the Arabian Peninsula, is also a major player in the region, with its vast oil wealth and strategic location giving it significant geopolitical clout.

Despite its many strengths and advantages, the Persian Gulf faces several challenges and threats. Environmental degradation, including pollution and overfishing, threatens the delicate ecosystem of the gulf and its marine life. Political instability and conflict, including the ongoing civil war in Yemen and tensions between Iran and other regional powers, also pose significant challenges for the region.

In conclusion, the Persian Gulf is a vital and fascinating region with significant economic, cultural, and geopolitical importance. Its ports serve as a hub for global trade, its oil and gas reserves fuel economic growth, and its cultural and historical significance has shaped the development of human civilization. Despite its many challenges, the Persian Gulf remains a critical region for the future of the Middle East and the world as a whole.


Physical features


The Iranian shore is mountainous, and there often are cliffs; elsewhere a narrow coastal plain with beaches, intertidal flats, and small estuaries borders the gulf. The coastal plain widens north of Būshehr (Bushire), Iran, and passes into the broad deltaic plain of the Tigris and Euphrates and Kārūn rivers. Cliffs are rare on the Arabian shore of the gulf, except around the base of the Qatar Peninsula and in the extreme southeast around the Strait of Hormuz, where they form the spectacular coast of the Musandam Peninsula. Most of the Arabian shore is bordered by sandy beaches, with many small islands enclosing small lagoons.

The gulf is shallow, rarely deeper than about 300 feet (90 metres), although depths exceeding 360 feet (110 metres) are found at its entrance and at isolated localities in its southeastern part. It is noticeably asymmetrical in profile, with the deepest water occurring along the Iranian coast and a broad shallow area, which is usually less than 120 feet (35 metres) deep, along the Arabian coast. There are numerous islands, some of which are salt plugs or domes and others merely accumulations of coral and skeletal debris.

The Persian Gulf receives only small amounts of river-borne sediment except in the northwest, where immense quantities of silt are deposited by the Tigris, Euphrates, and Kārūn rivers and other smaller streams as they empty into the gulf, by way of the Karoon river. The rivers reach their peak flow in spring and early summer, when the snow melts in the mountains; disastrous floods sometimes result. There are some ephemeral streams on the Iranian coast south of Būshehr, but virtually no fresh water flows into the gulf on its Arabian side. Large quantities of fine dust and, in places, quartz sand, however, are blown into the sea by predominant northwest winds from the desert areas of the surrounding lands. Biological, biochemical, and chemical processes produce considerable calcium carbonate in the form of skeletal debris and fine mud, which mixes with this land-derived detritus. The deeper parts of the Persian Gulf adjacent to the Iranian coast and the area around the Tigris-Euphrates delta are mainly floored with gray-green muds rich in calcium carbonate. The shallower areas to the southwest are covered with whitish gray or speckled skeletal sands and fine carbonate muds. Often the seafloor has been hardened and turned to rock by the deposition of calcium carbonate from the warm, salty waters. Chemical precipitation is abundant in the coastal waters, and sands and muds are produced that mix with the skeletal debris of the local sea life. These sediments are thrown up by the waves to form coastal islands that enclose lagoons. The high salinities and temperatures precipitate calcium sulfate and sodium chloride to form extensive coastal salt flats (sebkhas).


The present-day Persian Gulf, together with its northwestern continuation now infilled by the deposits of the Mesopotamian rivers, is the remains of a once much larger basin of deposition aligned northwest to southeast that existed throughout much of geologic history. In this basin vast quantities of sediments accumulated—mostly limestone and marls (a mixture of calcareous and silicate mud), together with evaporites and organic matter—which ultimately produced the area’s extensive oil resources.


The gulf has a notoriously unpleasant climate. Temperatures are high, though winters may be quite cool at the northwestern extremities. The sparse rainfall occurs mainly as sharp downpours between November and April and is higher in the northeast. Humidity is high. The little cloud cover is more prevalent in winter than in summer. Thunderstorms and fog are rare, but dust storms and haze occur frequently in summer. The shamal, a wind that blows predominantly from a north-northwest direction during the summer, is seldom strong and rarely reaches gale force. Squalls and waterspouts are common in autumn, when winds sometimes reach speeds of 95 miles (150 km) per hour within as short a time as five minutes. Intense heating of the land adjacent to the coasts leads to gentle offshore winds in the mornings and strong onshore winds in the afternoons and evenings.


The small freshwater inflow into the gulf is mostly from the Tigris, Euphrates, and Kārūn rivers. Surface-water temperatures range from 75 to 90 °F (24 to 32 °C) in the Strait of Hormuz to 60 to 90 °F (16 to 32 °C) in the extreme northwest. These high temperatures and a low influx of fresh water result in evaporation in excess of freshwater inflow; high salinities result, ranging from 37 to 38 parts per thousand in the entrance to 38 to 41 parts per thousand in the extreme northwest. Even greater salinities and temperatures are found in the waters of the lagoons on the Arabian shore. The tidal range varies from about 4 to 5 feet (1.2 to 1.5 metres) around Qatar and increases to 10 to 11 feet (3.0 to 3.4 metres) in the northwest and 9 to 10 feet (2.7 to 3.0 metres) in the extreme southeast. When onshore winds are strong, the level of the coastal waters, particularly in the southern gulf, may rise by as much as 8 feet (2.4 metres), causing extensive flooding of the low sebkhas. Tidal currents are strong (5 miles [8 km] per hour) at the entrance of the gulf but elsewhere—except between islands or in estuaries and lagoon entrances—rarely exceed one to 2 miles (3 km) per hour. The wind affects local currents and sometimes reverses them.

Waves rarely exceed 10 feet in height and are largest in the southern gulf. The swell from the Indian Ocean affects only the water at the entrance of the gulf; when it is opposed by wind, turbulent conditions result. The general circulation pattern in the gulf is counterclockwise and is characterized by its vertical nature: as surface water enters from the Indian Ocean, it is subject to evaporation, thus becoming denser and sinking to flow out into the Indian Ocean beneath the inflowing water from the open ocean.


Economic aspects

Biological and mineral resources

The waters of the area support many plants and animals, but the high temperatures and salinities lead to a diminution in the variety of flora and fauna typical of the Indian Ocean. Until the discovery of oil in Iran in 1908, the Persian Gulf area was important mainly for fishing, pearling, the building of dhows (lateen-rigged boats common in the region), sailcloth making, camel breeding, the making of reed mats, date growing, and the production of other minor products, such as red ochre from the islands in the south. The arid lands surrounding the gulf produced little else and, except for the rich alluvial lands of the Mesopotamian plain, supported only a small population of those engaged in fishing, date growing, and nomadic herding. Fishing has become highly commercialized. The traditional pearl-fishing industry has declined since the advent of Japanese cultivated pearls on world markets in the 1930s. Large fishing industries have been set up in Kuwait, Qatar, and Bahrain, and some countries have become exporters of fish. Yields in the northwest have been affected, however, by the construction of large dams on the rivers, which restrict the supply of nutrients into the Persian Gulf.

Persian Gulf Star Refinery boosts export of oil derivatives - IRNA English

Persian Gulf Star Refinery boosts export of oil derivatives – IRNA English.

Since World War II the Persian Gulf and the surrounding countries have come to account for a significant proportion of the world’s oil production. In addition, the area has approximately two-thirds of the world’s estimated proven oil reserves and one-third of the world’s estimated proven natural gas reserves. The region thus has acquired considerable strategic significance for the world’s industrialized countries. Exploration has remained active, and new reserves are continually being discovered, both on land and offshore. Control of these reserves has led to numerous legal wrangles among states about exact territorial limits and has been at least partially responsible for major conflicts in the region: the Iran-Iraq War of the 1980s, the Persian Gulf War of the early 1990s, and the Iraq War of the early 21st century. Large amounts of oil are refined locally, but most is exported to northwestern Europe, East Asia, and other areas of the world. Petrochemical and other petroleum-based industries, as well as consumer industries, have been developing rapidly in the gulf region.



For centuries a considerable sea trade has been carried on by local craft between the Persian Gulf and Africa and India; this has become completely dominated by incessant traffic of large tankers that carry oil from the large marine terminals at Khārg Island (Iran), Kuwait, Al-Dammām (Saudi Arabia), Bahrain, Port Rāshid (United Arab Emirates), and other locations to all parts of the world. The heavy traffic and the offshore oil installations have produced many hazards, despite the use of a system of radio-navigational stations and other technological advances.

Study and exploration

The Persian Gulf area was well known by early local navigators and Portuguese, British, and Dutch traders from the beginning of the 16th century. Useful bathymetric charts and sailing instructions appeared when the British commenced collecting hydrographic, meteorological, and oceanographic data at the end of the 18th century. The Danish Fisheries Expedition conducted important marine biological studies beginning in the 1930s, and the Japanese undertook further fisheries studies in the 1970s. Studies of the oceanography, geology, and sedimentology of the seafloor were made in the 1950s and ’60s by American and British scientists working from naval hydrographic vessels and by oil company research scientists; later this work was continued by German and American research expeditions and some studies were made in the northern gulf by the Kuwait Institute of Scientific Research. Oil companies have extensively investigated the deeper geologic structure, but generally, these have remained confidential.

The Persian Gulf is a marginal and semi-enclosed sea situated in the subtropical region of the Middle East between latitudes 24o and 30o N and longitudes 48o and 57o E . The Persian Gulf constitutes part of the Arabian Sea Ecoregion, and represents a realm of the tropical Indo-Pacific Ocean  It is a shallow sedimentary basin with an average depth of 35 m and a total area of approximately 240,000 km2.

Due to the high-latitude geographical position, the relative shallowness and the high evaporation rates, the Persian Gulf is characterized by extreme environmental conditions. Sea temperatures are markedly fluctuated between winter and summer seasons (15 – 36°C). Salinity can exceed 43 psu and may reach 70-80 psu in tidal pools and lagoons. Therefore, marine organisms in the Persian Gulf are living close to the limits of their environmental tolerance.

Despite these harsh environmental conditions, the Persian Gulf supports a range of coastal and marine ecosystems such as mangrove swamps, seagrass beds, coral reefs, and mud and sand flats.  These ecosystems contribute to the maintenance of genetic and biological diversity in the marine environment and provide valuable ecological and economic functions as they form feeding and nursery grounds for a variety of commercially important marine organisms.

However, these ecosystems are under ever-increasing pressure from anthropogenic activities that are associated with the rapid economic, social and industrial developments in the Persian Gulf countries. The Persian Gulf is considered among the highest anthropogenically impacted regions in the world . The coasts of the Persian Gulf are witnessing rapid industrialization and urbanization that contribute to the degradation of naturally stressed marine ecosystems. Coastal and marine environments are affected by intensive dredging and reclamation activities, and several sources of pollution, including industrial waste, brine waste waters, ports and refiners, oil spills, and domestic sewage. These threats warrant the designation of the Arabian Sea Ecoregion, including the Persian Gulf as ‘critically endangered by the International Union for the Conservation of Nature (IUCN) and the World Wildlife Fund (WWF) (

Due to its unique environmental setting, the Persian Gulf is increasingly receiving international scientific interest in studying the effects of environmental extremes on marine organisms and to investigate the potential impacts of future climate change on the ecological integrity of marine ecosystems.


The Growing Need for Sustainable Ecological Management of Marine Communities of the Persian Gulf

The Persian Gulf is a semi-enclosed marginal sea, connected to the Gulf of Oman through the 56 km wide Strait of Hormuz (Fig. 1). It is a major shipping route for ports in the Middle East and South Asia, and for the global oil transport industry, and its eight bordering countries include several that are experiencing a rapid and very extensive coastal development, chiefly for up-scale residential communities. The Persian Gulf’s geography, climate, and pattern of use put it at risk for various types of environmental degradation, and the current capacity for environmental management is inadequate. This article builds upon several recent reviews of the state of the Persian Gulf (, and makes recommendations for suitable steps to improve environmental management in the face of growing anthropogenic pressures.

figure 1

The Persian Gulf, 239,000 km2 in area, is a semi-enclosed marginal sea, has an average water depth of 36 m, a maximum internal depth of 94 m, a shallow broad southern margin along the coast of U.A.E., and a relatively narrow and deep north-eastern margin along the coast of Iran

Part 1: Physical and Biological Description

The marine environment of the Persian Gulf is characterized by extreme environmental conditions, which are attributed to its location and bathymetry. The Gulf experiences high rates of evaporation, which exceed the combined levels of rainfall and river discharge. As a result, an inverse estuarine and counterclockwise circulation pattern prevails in the Gulf. The northern part of the Strait of Hormuz serves as the entry point for surface water that penetrates deep into the Gulf along the Iranian coast. This wedge of less saline water increases in salinity and exits at depth through the Strait of Hormuz. During summer, the average surface water temperature in the Persian Gulf is 33°C, with the highest recorded temperature being 37.7°C. In contrast, the average winter SST ranges from 22°C near the Strait to 16°C near the head of the Gulf. The lowest recorded SST was 11.5°C. In winter, salinity levels as high as 43 have been observed toward the head of the Gulf.

Physical Environment

nterspersed with occasional outcrops of coral-dominated limestone habitats. Subtidal sediments consist of thin layers of relatively pure carbonate sands or mud over consolidated conglomerates. In areas with weaker currents, sand and shell gravel accumulate, providing habitat for infaunal and epibenthic organisms. Mudflats are the dominant intertidal habitats along the coastline of the western Gulf, where water movements are less turbulent. Due to the discharge of silt from the Tigris and Euphrates Rivers, 57% of the Kuwait coastline is characterized by gently sloping mudflats. These mudflats are often covered by dense, highly productive microbial mats, which form an essential habitat and food source for intertidal macrofauna.

Sabkhas are coastal flats at or just above the level of normal high tide, characterized by unconsolidated carbonate or siliciclastic sediments, diagenetic evaporite minerals, aeolian deposits, and a variable association of sedimentary structures. These areas are typically devoid of vegetation, or sparsely covered with dwarf shrubs and tussock grasses.

True coral reefs do not exist within the Persian Gulf, and corals generally form a veneer on areas of exposed limestone cap-rock. Owing to the friable nature of this substratum and repeated mass mortality of corals due to environmental extremes in the area, corals generally do not build true reef framework. Approximately 60 species of scleractinian coral have been described for the Persian Gulf, representing approximately one tenth of corals known for the Indo-Pacific and 15% of those in the Indian Ocean. The coral communities of the Gulf are depauperate, owing almost certainly to its environmental extremes, and are therefore quite distinct from those in the major biogeographic regions surrounding the Arabian Peninsula.

Ecology and Biogeography

The topics discussed in this passage have been previously covered by various authors. The typical coastal communities found in the Indian Ocean are present in the Persian Gulf, but are often represented in low numbers due to isolation and harsh environmental conditions. The naturally occurring mangroves in the Gulf are primarily of the Avicennia marina species and are found in lagoons and on leeward sides of spits, islands, and shoals along the Iranian coast as well as in Saudi Arabia, Bahrain, Oman, Qatar, and the U.A.E. However, they are absent in Iraq and Kuwait. The high salinity in the area leads to stunted growth and poor development of mangrove trees.

The seagrass communities of the Persian Gulf consist of three euryhaline species, Halodule univervis, Halophila ovalis, and Halophila stipulacea, and are prevalent along southern and western shores. These communities are important habitats for fishery species, including nursery habitats for many fish, and commercially important species such as Penaeus semisulcatus and Pinctada radiata. The seagrass beds also support the green turtle, Chelonia mydas, and the world’s second largest population of the endangered dugong, Dugong dugong.

Macroalgal beds are also present, often mixed in with seagrasses, and are vital settlement sites and nurseries for various fishes, shrimp post-larvae, and oyster spat. However, the extreme summer conditions in the area only allow for seasonal presence. Phytoplankton productivity is favored by high nutrient levels, but there is considerable disparity among studies characterizing the plankton communities of the Gulf.

The Gulf is occupied by various marine species such as dolphins, whales, and the Whaleshark Rhyncodon typus. The fish fauna is Indian Ocean derived, but species diversity is lower than that of the Gulf of Oman, and there are few endemic species. Deeper waters in the northern and eastern Gulf have higher species richness than the southern region, and there is significant seasonality in recruitment and adult movement of coastal fish communities.

The crustacea, mollusca, and echinodermata are the best-known invertebrate groups in the Persian Gulf and are important as food species throughout the region. However, these groups are less diverse compared to the Gulf of Oman, and the paucity of research available may exaggerate these trends. Polychaete species diversity and endemicity are higher in the Persian Gulf than in either the Arabian Sea or the Gulf of Oman.

Part 2: Human Impacts on the Persian Gulf Ecosystem

Fisheries and Conservation

Fishing in the Persian Gulf is largely artisanal, with a focus on demersal species in the south and west, and shrimp and pelagic fish in the north. The Gulf has significant fishery resources, estimated at 550,000 tonnes annually by the UN Food and Agriculture Organization, making it the most important renewable natural resource and second only to oil in importance. Despite regulations on fishing effort, many species have been heavily exploited, and fishing effort is already too high for most demersal species. Stock status data is limited and regulations are weak, inconsistently enforced, or inconsistent across jurisdictions.

Around 20 marine protected areas have been designated for conservation protection, covering 12,000 km2 in total. Commercial fishing is typically prohibited in these areas, as are activities such as construction or shore-based development. Similar restrictions apply to oil leases, with some success in policing, although enforcement is generally weak. Effective management of marine protected areas could help to lower rates of exploitation of fishery species and protect other valued species. Improving the enforcement of existing regulations could help Gulf nations to better manage and conserve their marine resources.

Hydrocarbon Pollution

The Persian Gulf region holds the world’s largest hydrocarbon reserve, with over 76 × 109 tonnes of recoverable oil and 32.4 × 1012 m3 of gas reserves. The area has approximately 800 offshore oil and gas platforms and 25 major oil terminals. The Strait of Hormuz sees about 25,000 tankers annually, carrying roughly 60% of all the oil transported by ships worldwide.

Oil exploration, production, transport, and military activities are the primary sources of pollution in the Persian Gulf. The most significant long-term threat is the chronic contamination of coastal waters, resulting from the constant discharge of oil from harbors, ballast water, terminals, atmospheric fallout, and sewage-plant effluents. During the Gulf War, Iraqi troops intentionally spilled an estimated 10.8 million barrels of oil from abandoned tankers and coastal terminals. This event affected over 700 km of coastline from southern Kuwait to northern Saudi Arabia, but the coastal benthic habitats have since remarkably recovered.

The high hydrocarbon content in the Persian Gulf has favored bacterial assemblages capable of mineralizing crude oils, aided by the warm and nutrient-rich waters of the region. Although hydrocarbon pollution levels are persistently high throughout the waters of the Persian Gulf, especially along the Iranian coast, the associated toxic compounds related to combustion of crude oils and metal contamination related to oil spills are not exceptionally high compared to impacted sites in northern Europe and North America.


The Persian Gulf is home to several major manufacturing industries such as fertilizer, chemical, petrochemical, mineral, and plastic production, as well as an expanding agricultural sector due to the availability of capital and demand for fresh produce. Unfortunately, these activities have led to the discharge of various chemicals, including heavy metals, oil and petroleum-based compounds, nutrients, and halogenated organics into the coastal marine sediments via wastewater. Despite high standards for wastewater treatment in the Gulf region, significant amounts of domestic and industrial wastewater still enter the local waters. While most sewage undergoes secondary or tertiary treatment before discharge, large amounts of nutrients and other pollutants also enter the Gulf from inland sources, such as rivers in southern Iran and southeastern Iraq, which are estimated to carry 300,000-500,000 m3 days-1 of wastewater to the Gulf. Agricultural runoff containing organic pollutants also enters river systems, leading to localized eutrophication and reduced oxygen levels in coastal waters.

Desalination, A Growing and Urbanized Population

The Persian Gulf region is home to major manufacturing industries producing fertilizers, chemicals, petrochemicals, minerals, and plastics. These industries, along with agricultural development, have led to the discharge of various chemicals including heavy metals, oil and petroleum-based compounds, nutrients, and halogenated organics into coastal marine sediments via wastewater.

Despite high standards for wastewater treatment throughout the Gulf region, significant amounts of domestic and industrial wastewater still enter local waters, including large quantities of nutrients and other pollutants from further inland. Agricultural runoff carrying organic pollutants also enters through river systems, causing localized eutrophication and lowered oxygen levels in coastal waters.

Desalination is the principal source of potable water in the region due to the shortage of freshwater resources, supplying from 66% to 90% of the water used. However, waste brine and pre- and post-treatment chemicals from desalination plants may pose a serious threat to the marine environment, with few studies examining the potential effects on Gulf marine fauna.

The countries bordering the Persian Gulf have experienced high rates of economic and population growth, leading to significant changes to large areas of ecologically productive coastal habitats throughout the Gulf. Coastal dredging and development for industrial, commercial, and residential use have altered intertidal flats, mangrove forests, fringing coral reefs, seagrass beds, and sandy embayments. There is a lack of capacity in environmental regulatory agencies to help guide this growth, resulting in negative environmental impacts.

Development in Dubai: Marine Ecosystems damaged by the Nakheel Marine Development Projects

Artificial islands, also known as man-made islands, are typically created by dredging sand or other seafloor materials and depositing them in a desired location, usually in shallow waters near the coast. While these islands can provide valuable space for development and infrastructure, they can also negatively impact marine ecosystems.

One way that artificial islands can damage marine ecosystems is through the destruction of natural habitats. The dredging and deposition of materials can disrupt or destroy habitats such as seagrass beds, coral reefs, and mangrove forests, which provide important breeding and feeding grounds for many marine species. The loss of these habitats can lead to declines in biodiversity and the loss of important ecosystem services, such as fisheries and coastal protection.

In addition to habitat destruction, constructing and operating artificial islands can also lead to pollution and other environmental impacts. Dredging and depositing materials can release sediment and other pollutants into the surrounding waters, harming marine organisms and reducing water quality. The development of infrastructure on the islands, such as ports, marinas, and hotels, can also lead to increased pollution and disturbance of marine life.

Creating artificial islands can also disrupt the natural flow of water and sediment, which can have far-reaching impacts on coastal ecosystems. Changes in water flow can affect nutrient cycling, sediment deposition, and the distribution of marine organisms, leading to changes in community structure and ecological function.

Finally, the creation of artificial islands can also lead to increased pressure on marine resources, particularly fisheries. The development of infrastructure on the islands can lead to increased fishing activity, leading to overfishing and depletion of fish stocks.

In summary, while artificial islands can provide valuable space for development and infrastructure, they can also significantly negatively impact marine ecosystems. It is important to carefully consider the potential environmental impacts of artificial island development and to take steps to minimize these impacts through effective planning, design, and management.

Coastal development projects in the Persian Gulf, particularly in Bahrain, Qatar, and the U.A.E., are expected to significantly and have long-lasting impacts on the region’s health. Although major developments are already in place, little information is available on their short-term and long-term environmental impacts. The scale of development can be seen in the growth of Dubai, where the government-owned developer Nakheel has constructed a series of large-scale, entirely man-made island-lagoon complexes along the coast since 2002, increasing Dubai’s coastline from about 70 to 1500 km. The effects of these developments on marine communities in Dubai may serve as an indication of what is to come in the region.

figure 2

This image displays the coastline of Dubai and showcases the offshore developments of Palm Jebel Ali, Palm Jumeirah, and The World (from left to right).

figure 3

The Atlantis Dubai Hotel in final stages of construction. The 1500-roomed hotel, aquarium, and theme park occupies a 45 ha site at the tip of the surrounding crescent directly seaward of the tip of Palm Jumeirah. It is 6 km seaward of the original coastline. Photo: K. Drouillard

In 2006, a collaboration between Nakheel and the United Nations University–Institute for Water, Environment and Health (UNU–INWEH) was established to develop an environmental management program for the marine ecosystems affected by the constructed island-lagoon complexes. As little information was available on the potential impacts on marine ecosystems, an environmental monitoring program was initiated, along with a suite of ecological studies to better understand the marine ecosystems present.

The results of the study demonstrate that the prevailing dredge and fill procedures generate sediment plumes that are both widespread and long-lasting, which is of particular concern as Nakheel plans further construction in Dubai waters. Additionally, the constructed islands permanently modify coastal water movement and sediment transport, with the extent and nature of the modification varying based on island shape and orientation. These modifications have significant long-term effects on the composition of infauna, which is influenced by the sediment type.

While the constructed islands provide new habitats for various species adapted to rocky shores, reefs, or shallow, sandy lagoons, there are substantial and long-term (decadal) effects on the composition of fauna associated with the constructed islands and breakwaters. These effects are due to successional processes and complex seasonal variation resulting from patterns of faunal migration and recruitment. The findings of this study are expected to be useful for evaluating the potential impacts of coastal development throughout the Persian Gulf.

figure 4

The snapper, Lutjanus ehrenbergii, sea urchins, and oysters living on the Nakheel breakwater at The World. Photo: Nakheel, with permission

The type of material used to construct breakwaters can affect some components of the benthic community, including corals, so that similar construction, but the use of different materials can lead to quite different environmental outcomes; and

Specific design aspects of an island development can introduce significant local, physical, and chemical changes that degrade habitat quality and favor undesirable species, or prevent colonization of the site by desired species of aquatic organism.

The benthic footprint of Palm Jumeirah was found to extend over 800 m beyond the outer crescent breakwater. The sediment composition within 800 m of the breakwater was dominated by silt and finer particles (<63 μm), unlike surface sediments typically found on the inner shelf along the Dubai coastline (≥125 μm). As a result, infaunal communities were dominated by polychaetes <800 m from the crescent, while small crustacea (Amphipoda, Isopoda, etc.) dominated further away. These fine sediments were prone to resuspension under moderate sea conditions, leading to high sedimentation rates on some parts of the rocky breakwaters. No studies have been conducted to determine this increased sedimentation’s impacts on native biota.

The construction of Palm Jebel Ali and other Nakheel constructions in close proximity resulted in the burial or heavy impact of most of the dense coral habitat in Dubai, with coastal development responsible for much of the loss and degradation of coral habitat.

Breakwater orientation had a significant impact on the benthic community that developed due to patterns of sediment deposition associated with differences in water movement and wave exposure. Windward breakwater communities had low levels of sediment deposition and were dominated by coral species, while leeward breakwater communities held higher levels of fine sediment and were dominated by algal turfs and oysters.

The presence of Palm Jumeirah had a substantial effect on the surrounding mid-water communities, with significantly higher abundances of phytoplankton on the east side of Palm Jumeirah than on the west. Plankton community composition differed substantially, with the eastern lee dominated by diatoms, while a range of dinoflagellate species dominated waters west of the development.

There was a significant difference in the flushing rates observed between the western and eastern halves of the large annular lagoon, which was not predicted by modeling before construction. Breakwaters <5.5 years old were dominated by algae and oysters, while corals became the dominant member of the benthic community on breakwaters >25 years, with abundances that exceeded those on natural reefs in the area.

Seasonality affects benthic and fish communities substantially, with recruitment of corals highly seasonal, occurring in late spring and early summer. Differences among species in the timing of recruitment may lead to different assemblages developing on breakwaters constructed at different times of the year. Higher densities of reef-associated fish are associated with breakwaters than natural reefs during the warmer summer and autumn seasons.

Cast concrete in various configurations and quarried gabbro, sandstone, and limestone have been used in the construction of breakwaters in the Gulf, and these materials differentially impact recruitment of corals in areas where coral recruitment is high. However, such effects are local, and site-specific differences in larval supply appear more important in structuring the wider benthic community on breakwaters in this area.

The construction of the majority of coastal developments in the Persian Gulf has relied solely on locally dredged marine sediments for material, with quantities being enormous. The effects of these extensive dredging activities on local marine communities are poorly understood. The construction of Palm Jumeirah also resulted in trench-like borrow pits encircling the project, filled with flocculent, suspended fine sediment that is sometimes anoxic. The organisms present were predominantly species typical of very fine sediments (e.g., Polychaetae).

Harmful Algal Blooms Within the Persian Gulf

Harmful algal blooms (HABs) occur when certain species of phytoplankton produce toxins or reach high levels of biomass that can lead to reduced light penetration or anoxia, which can affect the natural community and food chain. Over the past 30 years, HABs have become more frequent and widespread worldwide.

Enclosed, shallow inland seas that are increasingly affected by human activity are more susceptible to the invasion and establishment of these harmful algal populations. Ballast-laden ships can transfer HAB cells from source areas to new environments, as demonstrated by Hamza (2006) in the Gulf. The new cells must survive in the new environment and outcompete the existing phytoplankton communities to make the most of available resources.

The Gulf is prone to HAB invasions and outbreaks due to its physical geography and global shipping traffic, although the frequency of outbreaks has historically been low and their duration limited. For example, a bloom of Gymnodinium sp. in Kuwait Bay in 1999 resulted in a fish kill, but the ecological damage was limited due to predatory ciliates that consumed the cells. However, the nutrient conditions that initiated the bloom persisted.

In August-September 2001, Kuwait Bay experienced another fish kill due to a bloom of the fish-killing diatom Ceratium furca, which was facilitated by a stable water column, warm waters, and elevated nutrient levels. This bloom depressed oxygen levels and led to a secondary HAB event involving putative toxin-producing dinoflagellates, which contaminated the food chain with several marine biotoxins.

In 2008-2009, a large and prolonged HAB event occurred in the southern Gulf, starting in the Gulf of Oman and expanding north along the Musandam coast and into the Gulf as far as the shores of Dubai. The dominant species was Cochlodinium polykrikoides, a fish-killing species common in other parts of the world. This bloom also damaged other marine fauna, particularly the hard coral communities and associated fish fauna. Through rRNA gene sequence analysis, it was confirmed that the outbreak was due to a strain of C. polykrikoides commonly found in American and Malaysian waters, indicating the global expansion of this invasive species, probably through ballast water discharge. The demise of the bloom may indicate that the physical environment was unsuitable for the HAB species, or that the natural cycle of the bloom sequence had ended, leaving cells present for future bloom opportunities. The arrival of this invasive species in Gulf waters is a cause for concern.

figure 5

Progression of the 2008–2009 harmful algal bloom in the Persian Gulf. Distribution of chlorophyll concentration is shown for dates in October and November 2008, and January 2009. Initially present along the eastern coast of Oman, it developed not only west of the Strait of Hormuz, particularly along the Iranian coast, but also down the coast of the United Arab Emirates