**3. Environmental stressors**

The Arabian Gulf is facing multiple natural and anthropogenic environmental stressors. The unique physical and chemical settings represented by extremes in temperature and salinity accompanied by anthropogenic impacts may pose threats to marine species diversity and ecosystems integrity. The naturally stressed marine ecosystems are subjected directly or indirectly to human actions ranging from habitat destruction by coastal reclamation to pollution from a variety of land-based activities.

that frequently reported in recent years in Kuwait, Oman, Saudi Arabia and United Arab

Extensive blooms (i.e. red tides) have been causing severe ecological and economical impacts in the Arabian Gulf. For instance, the massive blooms affected the Arabian Gulf from August 2008 to May 2009 caused widespread fish kills, damaged coral reefs, restricted fishing activities, impacted tourism industry, and interrupted desalination operations. The 2008-2009 harmful algal blooms were associated with the dinoflagellate species *Cochlodinium*, which was the first

Effects of climate change and global warming on natural ecosystems and human well-being are major global concerns (Sheppard, 2006). Although climate change is directly or indirectly attributed to anthropogenic sources, it generally results from large-scale interactions for several variables over a very long time. There are three main features of the global climatic changes; namely, extreme sea-surface temperatures, marine acidification, and sea-level rise

Although ecosystems in the Arabian Gulf are adapted to extreme environmental conditions, anomalous sea-surface temperatures due to climatic changes may result in severe impacts on the integrity of theses vulnerable ecosystems. The massive bleaching and subsequent mortality of corals in the Arabian Gulf occurred in 1996 and 1998 with maximum sea-surface tempera‐

2011). Although most of the Arabian Gulf countries were affected by these beaching events, Bahrain was the worst affected with an estimated overall loss of 97% of live corals. Recovery of Bahrain reefs was limited in the subsequent years due to continuing coastal developments that are associated with intensive dredging and reclamation (Burt et al., 2013). Additionally, warmer waters can also lead to oxygen depletion and suffocation of marine organisms. Higher temperatures where attributed to the massive fish mortalities along the coasts of Qatar (Al-

The harmful effects of increasing atmospheric levels of carbon dioxide (CO2) and other greenhouse gases are reflected on the environment and human health. The Arabian Gulf is a major sink for atmospheric CO2, which may lead to acidification of the marine environment. Measurements of pH concentration in surface waters of the Arabian Gulf over a four year period (2007-2010) indicated that waters are becoming increasingly acidic with time (Uddin et al., 2012). Increasing acidity in the marine environment is critical for several organisms,

Sea-level rise is another effect of global climatic change that poses threats on coastlines of the Arabian Gulf. Bahrain as a group of low land islands is particularly threatened by any sea-level rise due to global climatic change. Al-Jeneid et al. (2008) have predicted that 77 km2 of Bahrain's land could be inundated with seawater in the case of a rise of the sea level by 0.5 m. These areas are harboring sensitive ecosystems such as mangroves, and interti‐

C, respectively (Sheppard and Loughland, 2002; Burt et al.,

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time to be observed in the Arabian Gulf waters (Richlen et al., 2010).

that may pose potential risks to marine ecosystems in the Arabian Gulf.

C and 38.0 <sup>o</sup>

including corals, molluscs and calcareous phytoplankton.

Emirates (Hamza and Munawar, 2009).

tures reaching 37.3 o

Ansi et al., 2002).

dal mudflats.

Environmental impacts on marine ecosystems could be generally attributed to natural or anthropogenic stressors. However, distinguishing between natural and anthropogenic stressors might be difficult due to the complexity of ecosystems responses to the variety of disturbances. For instance, anthropogenic impacts on ecosystems may not be detected until they are interacted with natural environmental stressors. Additionally, some environmental changes in ecosystems that appear to be natural may have been influenced by anthropogenic actions.

#### **3.1. Natural stressors**

Natural stressors in marine environment have a large number of forms and sources. Environ‐ mental extremes represent stressors that interfere with normal functioning of marine ecosys‐ tems (Breitburg and Riedel, 2005). The arid physical setting of the Arabian Gulf represented by extreme levels of salinity and temperature has pronounced effects on physiological aspects of marine organisms as well as their diversity, abundance and spatial distribution.

Physiological stresses are reflected in the dwarfism phenomena in fauna and flora inhabiting areas with high levels of salinity. For example, Price (2002) attributed the occurrence of dwarfism in echinoderms to the high salinity waters of the Arabian Gulf. Similarly, Naser and Hoad (2011) investigated morphological characteristics of mangroves in two distinctive coastal areas in Bahrain. The first area of mangroves receives input of low-salinity water from nearby farms, and underground seepage with salinity ranging between 5 psu in winter and 29 psu in summer. Salinity of the coastal water in the second area of mangroves can exceed 44 psu. This study reported differences in tree heights of mangroves ranging from 1.5 to 2.5 m in the coastal area compared with 4 to 5 m in the first area that receives low-salinity water.

Generally, extreme environmental conditions in the Arabian Gulf are reflected in reduced levels of species richness (Price, 2002). However, it is recognized that the Arabian Gulf has distinctive marine assemblages as well as habitats (Sheppard et al., 1992). Therefore, it can be argued that while species richness is relatively low, change in species composition along a spatial gradient is high (Price, 2002).

Stressors of biological sources such as invasive species and algal blooms could play important roles in ecosystems degradation in the Arabian Gulf. With more than 25 000 oil tankers navigating through the Strait of Hormuz each year (Literathy et al., 2002), the introduction of aquatic invasive species via ballast water is considered one of the major threats facing the marine environment in the Arabian Gulf. Hamza (2006) reported several exotic phytoplankton and zooplankton species in water samples collected from ballast water tanks of a gas tanker stopped along the United Arab Emirates coastal area. Some of these exotic species, particularly dinoflagellate organisms, are linked to the red tide and fish kill that frequently reported in recent years in Kuwait, Oman, Saudi Arabia and United Arab Emirates (Hamza and Munawar, 2009).

accompanied by anthropogenic impacts may pose threats to marine species diversity and ecosystems integrity. The naturally stressed marine ecosystems are subjected directly or indirectly to human actions ranging from habitat destruction by coastal reclamation to

Environmental impacts on marine ecosystems could be generally attributed to natural or anthropogenic stressors. However, distinguishing between natural and anthropogenic stressors might be difficult due to the complexity of ecosystems responses to the variety of disturbances. For instance, anthropogenic impacts on ecosystems may not be detected until they are interacted with natural environmental stressors. Additionally, some environmental changes in ecosystems that appear to be natural may have been influenced by anthropogenic

Natural stressors in marine environment have a large number of forms and sources. Environ‐ mental extremes represent stressors that interfere with normal functioning of marine ecosys‐ tems (Breitburg and Riedel, 2005). The arid physical setting of the Arabian Gulf represented by extreme levels of salinity and temperature has pronounced effects on physiological aspects

Physiological stresses are reflected in the dwarfism phenomena in fauna and flora inhabiting areas with high levels of salinity. For example, Price (2002) attributed the occurrence of dwarfism in echinoderms to the high salinity waters of the Arabian Gulf. Similarly, Naser and Hoad (2011) investigated morphological characteristics of mangroves in two distinctive coastal areas in Bahrain. The first area of mangroves receives input of low-salinity water from nearby farms, and underground seepage with salinity ranging between 5 psu in winter and 29 psu in summer. Salinity of the coastal water in the second area of mangroves can exceed 44 psu. This study reported differences in tree heights of mangroves ranging from 1.5 to 2.5 m in the coastal

Generally, extreme environmental conditions in the Arabian Gulf are reflected in reduced levels of species richness (Price, 2002). However, it is recognized that the Arabian Gulf has distinctive marine assemblages as well as habitats (Sheppard et al., 1992). Therefore, it can be argued that while species richness is relatively low, change in species composition along a

Stressors of biological sources such as invasive species and algal blooms could play important roles in ecosystems degradation in the Arabian Gulf. With more than 25 000 oil tankers navigating through the Strait of Hormuz each year (Literathy et al., 2002), the introduction of aquatic invasive species via ballast water is considered one of the major threats facing the marine environment in the Arabian Gulf. Hamza (2006) reported several exotic phytoplankton and zooplankton species in water samples collected from ballast water tanks of a gas tanker stopped along the United Arab Emirates coastal area. Some of these exotic species, particularly dinoflagellate organisms, are linked to the red tide and fish kill

of marine organisms as well as their diversity, abundance and spatial distribution.

area compared with 4 to 5 m in the first area that receives low-salinity water.

pollution from a variety of land-based activities.

302 Biodiversity - The Dynamic Balance of the Planet

actions.

**3.1. Natural stressors**

spatial gradient is high (Price, 2002).

Extensive blooms (i.e. red tides) have been causing severe ecological and economical impacts in the Arabian Gulf. For instance, the massive blooms affected the Arabian Gulf from August 2008 to May 2009 caused widespread fish kills, damaged coral reefs, restricted fishing activities, impacted tourism industry, and interrupted desalination operations. The 2008-2009 harmful algal blooms were associated with the dinoflagellate species *Cochlodinium*, which was the first time to be observed in the Arabian Gulf waters (Richlen et al., 2010).

Effects of climate change and global warming on natural ecosystems and human well-being are major global concerns (Sheppard, 2006). Although climate change is directly or indirectly attributed to anthropogenic sources, it generally results from large-scale interactions for several variables over a very long time. There are three main features of the global climatic changes; namely, extreme sea-surface temperatures, marine acidification, and sea-level rise that may pose potential risks to marine ecosystems in the Arabian Gulf.

Although ecosystems in the Arabian Gulf are adapted to extreme environmental conditions, anomalous sea-surface temperatures due to climatic changes may result in severe impacts on the integrity of theses vulnerable ecosystems. The massive bleaching and subsequent mortality of corals in the Arabian Gulf occurred in 1996 and 1998 with maximum sea-surface tempera‐ tures reaching 37.3 o C and 38.0 <sup>o</sup> C, respectively (Sheppard and Loughland, 2002; Burt et al., 2011). Although most of the Arabian Gulf countries were affected by these beaching events, Bahrain was the worst affected with an estimated overall loss of 97% of live corals. Recovery of Bahrain reefs was limited in the subsequent years due to continuing coastal developments that are associated with intensive dredging and reclamation (Burt et al., 2013). Additionally, warmer waters can also lead to oxygen depletion and suffocation of marine organisms. Higher temperatures where attributed to the massive fish mortalities along the coasts of Qatar (Al-Ansi et al., 2002).

The harmful effects of increasing atmospheric levels of carbon dioxide (CO2) and other greenhouse gases are reflected on the environment and human health. The Arabian Gulf is a major sink for atmospheric CO2, which may lead to acidification of the marine environment. Measurements of pH concentration in surface waters of the Arabian Gulf over a four year period (2007-2010) indicated that waters are becoming increasingly acidic with time (Uddin et al., 2012). Increasing acidity in the marine environment is critical for several organisms, including corals, molluscs and calcareous phytoplankton.

Sea-level rise is another effect of global climatic change that poses threats on coastlines of the Arabian Gulf. Bahrain as a group of low land islands is particularly threatened by any sea-level rise due to global climatic change. Al-Jeneid et al. (2008) have predicted that 77 km2 of Bahrain's land could be inundated with seawater in the case of a rise of the sea level by 0.5 m. These areas are harboring sensitive ecosystems such as mangroves, and interti‐ dal mudflats.

### **3.2. Anthropogenic impacts**

#### *3.2.1. Reclamation and dredging*

Coastal and marine environments in the Arabian Gulf are the prime target for most of the major housing, recreational, and economic developments (Naser et al., 2008). Coastal devel‐ opments along the Arabian Gulf have accelerated at an unprecedented rate in the past decade to accommodate large-scale projects, including artificial islands, waterfront cities, ports and marinas (Khan, 2007).

levels (Al-Wedaei et al, 2011). Dredging and reclamation activities have resulted in the loss of many prime mudflats that support shorebird populations (Figure 4), and the degradation of coral reefs due to sediment runoff and the increase levels of turbidity (Al-Sayed et al., 2008).

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305

**Figure 2.** Sand and mud materials are pumped from a marine burrow area into the reclamation site. 'Dyar Al Muhar‐

The Arabian Gulf countries have witnessed a rapid industrial growth, mainly in the sectors of oil refining and petrochemical industries. These major industries are discharging wastewater containing a variety of chemicals, including heavy metals, hydrocarbon compounds, and nutrients (Sale et al., 2010). Petroleum refinery wastewaters are composed of different chemicals, which include oil and greases, phenols, sulphides, ammonia, suspended solids, and heavy metals like chromium, iron, nickel, copper, molybdenum, selenium, vanadium and zinc (Wake, 2005). Coastal and marine environments receiving intensive industrial effluents along the coastline of the Arabian Gulf are recognized as hotspots for high concentrations of

Naser (2013b) investigated the effects of industrial wastewater discharges that characterized by high inputs of heavy metals and hydrocarbons on crustacean assemblages along the eastern coastline of Bahrain. This coastline is heavily occupied by industrial facilities including the oil refinery, aluminum smelters and desalination plants. This study indicated that the analyzed heavy metals exhibited higher levels of concentrations in sediments influenced by industrial discharges. The study also argued that the synergistic effects of industrial effluents that contain

hydrocarbons (De Mora et al., 2004; 2010) and heavy metals (Naser, 2012a; 2013a).

raq' development in Bahrain (2013).

*3.2.2. Industrial effluents*

Habitat destruction due to intensive reclamation and dredging activities is the prime threat for biodiversity loss and ecosystem degradation in the Arabian Gulf. It is estimated that more than 40% of the coasts of the Arabian Gulf have been developed (Hamza and Munawar, 2009). Examples of large-scale coastal developments in the Arabian Gulf include 'Palm Islands' and 'The World' in Dubai, United Arab Emirates, 'The Pearl' in Qatar, 'Al Khaleej' and 'Half Moon Bay' in Saudi Arabia 'Pearl City' in Kuwait, and 'Durrat Al Bahrain', 'Amwaj', and 'Dyar Al Muharraq' in Bahrain.

It is likely that reclamation will accelerate in the coming decades in order to secure land for large-scale projects as populations in the Arabian Gulf countries continue to grow. This is reflected in the long-term land use strategies and master plans in the Arabian Gulf. For instance, Bahrain National Land Use Strategy 2030 recognizes reclamation as the major option for securing the future needs for land, indicating that coastal environment will continue to be the major focus for developmental projects in the coming future (Naser, 2011b).

Given its limited land area (762 km2 ), Bahrain has markedly been affected by coastal devel‐ opments. Presently, reclamation activities in Bahrain resulted in the addition of around 95 km2 representing an increase of 12% of the total land area (Naser, 2011b). Additionally, more than 80 % of Bahrain's coastline has extensively been modified due reclamation activities (Fuller, 2005).

Typically, reclamation in the Arabian Gulf is conducted by extracting sand and mud from designated marine borrow areas then dumping them into the coastal and shallow subtidal areas (Figure 2). Alternatively, reclamation could be carried out by infilling the coastline by rocks and sands extracted from quarries (Figure 3).

Dredging and reclamation processes are associated with short and long term biological, physical and chemical impacts. These activities involve the direct removal of macrobenthos and permanent modification of the physical environment. Deposition of dredged material during reclamation process may result in physically smothering the coastal and subtidal habitats and deoxygenating the underlining sediments (Allan et al., 2008). Reclaimed lands could also interfere with water circulation and subsequently alter the salinity (Al-Jamali et al., 2005). These physical and chemical alternations may reduce biodiversity, richness, abundance and biomass of marine organisms (Tu Do et al., 2012).

Additionally, dredging activities may contribute directly or indirectly to the loss of seagrass beds in the Arabian Gulf due to direct physical removal and burial, and the increase in turbidity levels (Al-Wedaei et al, 2011). Dredging and reclamation activities have resulted in the loss of many prime mudflats that support shorebird populations (Figure 4), and the degradation of coral reefs due to sediment runoff and the increase levels of turbidity (Al-Sayed et al., 2008).

**Figure 2.** Sand and mud materials are pumped from a marine burrow area into the reclamation site. 'Dyar Al Muhar‐ raq' development in Bahrain (2013).

#### *3.2.2. Industrial effluents*

**3.2. Anthropogenic impacts**

304 Biodiversity - The Dynamic Balance of the Planet

*3.2.1. Reclamation and dredging*

marinas (Khan, 2007).

Al Muharraq' in Bahrain.

km2

(Fuller, 2005).

Given its limited land area (762 km2

rocks and sands extracted from quarries (Figure 3).

and biomass of marine organisms (Tu Do et al., 2012).

Coastal and marine environments in the Arabian Gulf are the prime target for most of the major housing, recreational, and economic developments (Naser et al., 2008). Coastal devel‐ opments along the Arabian Gulf have accelerated at an unprecedented rate in the past decade to accommodate large-scale projects, including artificial islands, waterfront cities, ports and

Habitat destruction due to intensive reclamation and dredging activities is the prime threat for biodiversity loss and ecosystem degradation in the Arabian Gulf. It is estimated that more than 40% of the coasts of the Arabian Gulf have been developed (Hamza and Munawar, 2009). Examples of large-scale coastal developments in the Arabian Gulf include 'Palm Islands' and 'The World' in Dubai, United Arab Emirates, 'The Pearl' in Qatar, 'Al Khaleej' and 'Half Moon Bay' in Saudi Arabia 'Pearl City' in Kuwait, and 'Durrat Al Bahrain', 'Amwaj', and 'Dyar

It is likely that reclamation will accelerate in the coming decades in order to secure land for large-scale projects as populations in the Arabian Gulf countries continue to grow. This is reflected in the long-term land use strategies and master plans in the Arabian Gulf. For instance, Bahrain National Land Use Strategy 2030 recognizes reclamation as the major option for securing the future needs for land, indicating that coastal environment will continue to be

opments. Presently, reclamation activities in Bahrain resulted in the addition of around 95

Typically, reclamation in the Arabian Gulf is conducted by extracting sand and mud from designated marine borrow areas then dumping them into the coastal and shallow subtidal areas (Figure 2). Alternatively, reclamation could be carried out by infilling the coastline by

Dredging and reclamation processes are associated with short and long term biological, physical and chemical impacts. These activities involve the direct removal of macrobenthos and permanent modification of the physical environment. Deposition of dredged material during reclamation process may result in physically smothering the coastal and subtidal habitats and deoxygenating the underlining sediments (Allan et al., 2008). Reclaimed lands could also interfere with water circulation and subsequently alter the salinity (Al-Jamali et al., 2005). These physical and chemical alternations may reduce biodiversity, richness, abundance

Additionally, dredging activities may contribute directly or indirectly to the loss of seagrass beds in the Arabian Gulf due to direct physical removal and burial, and the increase in turbidity

 representing an increase of 12% of the total land area (Naser, 2011b). Additionally, more than 80 % of Bahrain's coastline has extensively been modified due reclamation activities

), Bahrain has markedly been affected by coastal devel‐

the major focus for developmental projects in the coming future (Naser, 2011b).

The Arabian Gulf countries have witnessed a rapid industrial growth, mainly in the sectors of oil refining and petrochemical industries. These major industries are discharging wastewater containing a variety of chemicals, including heavy metals, hydrocarbon compounds, and nutrients (Sale et al., 2010). Petroleum refinery wastewaters are composed of different chemicals, which include oil and greases, phenols, sulphides, ammonia, suspended solids, and heavy metals like chromium, iron, nickel, copper, molybdenum, selenium, vanadium and zinc (Wake, 2005). Coastal and marine environments receiving intensive industrial effluents along the coastline of the Arabian Gulf are recognized as hotspots for high concentrations of hydrocarbons (De Mora et al., 2004; 2010) and heavy metals (Naser, 2012a; 2013a).

Naser (2013b) investigated the effects of industrial wastewater discharges that characterized by high inputs of heavy metals and hydrocarbons on crustacean assemblages along the eastern coastline of Bahrain. This coastline is heavily occupied by industrial facilities including the oil refinery, aluminum smelters and desalination plants. This study indicated that the analyzed heavy metals exhibited higher levels of concentrations in sediments influenced by industrial discharges. The study also argued that the synergistic effects of industrial effluents that contain

high levels pollutants, brine discharges, and sedimentation due to intensive dredging and reclamation activities were reflected on the reduced levels of crustacean diversity and

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The flushing time of seawater in the Arabian Gulf is ranging between 3 and 5 years. Therefore, pollutants, including heavy metals and hydrocarbons are likely to reside in the Arabian Gulf for a considerable time. Continuous inputs of industrial effluents from different anthropogenic sources in the Arabian Gulf could be critical for both marine ecosystems and humans who rely

The Arabian Gulf countries are witnessing rapid industrial development and population growth, which increase the need for fresh water (Smith et al., 2007). Due to the low precipitation and high aridity in the Arabian Gulf countries, most of the fresh water needs are being obtained from seawater through the various processes of desalination, including multi-stage flash (MSF), and seawater/brackish reverse osmosis (RO) (Hashim and Hajjaj, 2005). It is estimated that the amount of desalinated water in the Arabian Gulf countries accounts for more than

Large quantities of reject water from desalination plants are being discharged on a daily basis to coastal and subtidal areas in the Arabian Gulf. Therefore, Hypersaline water discharges from desalination plants are increasingly becoming a serious threat to marine ecosystems in

Coastal and marine environments receiving these discharges are typically subject to chemical and physical alterations. Desalination effluents are commonly associated with harmful chemical components, including heavy metals, antiscaling, antifouling, antifoaming, and anticorrosion additive substances (Lattemann and Hopner, 2008). Additionally, discharges from desalination processes may alter physically and chemically the characteristics of receiv‐ ing seawater, including water temperature and salinity. These alterations in seawater quality, temperature, dissolved oxygen and salt concentration may severely affect several marine

Naser (2013c) investigated the effects of tow major desalination plants that use MSF and RO technologies on macrobenthic assemblages. The study found reduced levels of biodiversity and abundance in areas adjacent to the outlet of MSF reflecting severe impacts on macrobenthic assemblages caused by brine effluents that are associated with high temperatures, salinities,

The demand for desalinated water in the Arabian Gulf will increase in the coming future (Dawoud and Al-Mulla, 2012). This may result in cumulative impacts from the brine dis‐ charges leading to substantial fluctuations in salinity levels. It is forecasted that brine discharge will increase the salinity of the Arabian Gulf (Smith et al., 2007). Bashititalshaaer et al. (2011) predicted that brine discharge will increase the salinity of the Arabian Gulf by 2.24 g l -1 in 2050. This marked increase in seawater salinity could arguably be critical to the naturally stressed

abundance in the sampling stations.

*3.2.3. Desalination effluents*

organisms and assemblages.

marine ecosystems in the Arabian Gulf.

on marine resources for food, recreation and industry.

the Arabian Gulf (Areiqat and Mohamed, 2005).

60% of the world's total production (Lattemann and Hopner, 2008).

and a range of chemical and heavy metal pollutants (Figure 5).

**Figure 3.** Rocks and sands extracted from nearby quarries are used to reclaim a coastal area along the eastern coast‐ line of Bahrain (2012).

**Figure 4.** A mudflat along the northern coastline of Bahrain that supports wader birds is proposed to be reclaimed, which my result in a loss of important feeding grounds for bird populations (2012).

high levels pollutants, brine discharges, and sedimentation due to intensive dredging and reclamation activities were reflected on the reduced levels of crustacean diversity and abundance in the sampling stations.

The flushing time of seawater in the Arabian Gulf is ranging between 3 and 5 years. Therefore, pollutants, including heavy metals and hydrocarbons are likely to reside in the Arabian Gulf for a considerable time. Continuous inputs of industrial effluents from different anthropogenic sources in the Arabian Gulf could be critical for both marine ecosystems and humans who rely on marine resources for food, recreation and industry.

#### *3.2.3. Desalination effluents*

**Figure 3.** Rocks and sands extracted from nearby quarries are used to reclaim a coastal area along the eastern coast‐

**Figure 4.** A mudflat along the northern coastline of Bahrain that supports wader birds is proposed to be reclaimed,

which my result in a loss of important feeding grounds for bird populations (2012).

line of Bahrain (2012).

306 Biodiversity - The Dynamic Balance of the Planet

The Arabian Gulf countries are witnessing rapid industrial development and population growth, which increase the need for fresh water (Smith et al., 2007). Due to the low precipitation and high aridity in the Arabian Gulf countries, most of the fresh water needs are being obtained from seawater through the various processes of desalination, including multi-stage flash (MSF), and seawater/brackish reverse osmosis (RO) (Hashim and Hajjaj, 2005). It is estimated that the amount of desalinated water in the Arabian Gulf countries accounts for more than 60% of the world's total production (Lattemann and Hopner, 2008).

Large quantities of reject water from desalination plants are being discharged on a daily basis to coastal and subtidal areas in the Arabian Gulf. Therefore, Hypersaline water discharges from desalination plants are increasingly becoming a serious threat to marine ecosystems in the Arabian Gulf (Areiqat and Mohamed, 2005).

Coastal and marine environments receiving these discharges are typically subject to chemical and physical alterations. Desalination effluents are commonly associated with harmful chemical components, including heavy metals, antiscaling, antifouling, antifoaming, and anticorrosion additive substances (Lattemann and Hopner, 2008). Additionally, discharges from desalination processes may alter physically and chemically the characteristics of receiv‐ ing seawater, including water temperature and salinity. These alterations in seawater quality, temperature, dissolved oxygen and salt concentration may severely affect several marine organisms and assemblages.

Naser (2013c) investigated the effects of tow major desalination plants that use MSF and RO technologies on macrobenthic assemblages. The study found reduced levels of biodiversity and abundance in areas adjacent to the outlet of MSF reflecting severe impacts on macrobenthic assemblages caused by brine effluents that are associated with high temperatures, salinities, and a range of chemical and heavy metal pollutants (Figure 5).

The demand for desalinated water in the Arabian Gulf will increase in the coming future (Dawoud and Al-Mulla, 2012). This may result in cumulative impacts from the brine dis‐ charges leading to substantial fluctuations in salinity levels. It is forecasted that brine discharge will increase the salinity of the Arabian Gulf (Smith et al., 2007). Bashititalshaaer et al. (2011) predicted that brine discharge will increase the salinity of the Arabian Gulf by 2.24 g l -1 in 2050. This marked increase in seawater salinity could arguably be critical to the naturally stressed marine ecosystems in the Arabian Gulf.

reflecting severe habitat degradation in the nearby marine environment. Additionally, influenced areas were characterized by marked increase in organic enrichment, mainly

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309

The Arabian Gulf is considered the largest reserve of oil in the world (Literathy et al., 2002). Consequently, coastal and marine environments in the Arabian Gulf are under permanent threat from oil related pollution. Oil exploration, production, and transport have been major contributors to pollution in the Arabian Gulf. Sources of oil spills in the Arabian Gulf include offshore oil wells, underwater pipelines, oil tanker incidents, oil terminals, loading and handling operations, weathered oil and tar balls, illegal dumping of ballast water, and military

The Arabian Gulf has been a scene for major oil spill incidents in the world. Bahrain experi‐ enced one of the earliest major oil spills in the Arabian Gulf in 1980. A large oil slick (20,000 barrels) invaded the north and west coasts of Bahrain causing severe ecological and economical damages (Brown and James, 1985). This major incident was a precursor for establishing the first governmental authority concerned with the protection of environment in Bahrain in 1980; namely, the Environmental Protection Committee (EPC). The most notorious oil spill reported in the Arabian Gulf occurred during the 1991 Gulf War. An estimated 10.8 million barrels of

Oil pollution adversely affects marine ecosystems by reducing photosynthetic rates in phytoplankton and marine algae, accumulating toxic chemicals in several benthic organisms, and contaminating human food chains with carcinogenic substances. Seabirds and intertidal waders are predominantly vulnerable to oil pollution. For instance, several seabirds suffered severe mortality (22−50%) during the 1991 oil spill in the Arabian Gulf (Evans et al., 1993). Environmental consequences of long-term chronic oil pollution include degradation of sensitive ecosystems such as seagrass bed, coral reefs and mangroves, which may subsequently

Conservation biology is an integrated, multidisciplinary scientific field that has developed in response to the challenge of preserving species and ecosystems. Valued ecosystem components in the Arabian Gulf are facing several challenges due to habitat destruction, fragmentation, degradation and pollution. These are reflected in the decline in regional coral reefs due to natural and anthropogenic stressors, the loss of prime mudflats and mangroves swamps and seagrass beds due to intensive dredging and reclamation activities and anthropogenic effluents. Therefore, effective conservation and management of marine ecosystems in the Arabian Gulf is becoming an urgent need in order to protect and sustain these vulnerable ecosystems. Additionally, effectively managed ecosystems provide a range of essential environmental services that contribute to economic, social and cultural aspirations in the

oil were spilled in the Arabian Gulf waters (Massoud et al., 1998).

lead to decline in fish stocks and other renewable marine resources.

**4. Conservation and management**

ammonia and phosphate.

activities (Sale et al., 2010).

*3.2.5. Oil pollution*

**Figure 5.** Marine organisms at the proximities of desalination plants are influenced by chemical, physical and thermal pollution. Reduced levels of diversity and abundance of macrobenthos were recorded adjacent the outlet of this MSF desalination plant along the eastern coastline of Bahrain (2012).

#### *3.2.4. Sewage discharges*

Sewage effluents are considered one of the most common anthropogenic disturbances of marine ecosystems in the Arabian Gulf. Despite high standards of sewage treatment (i.e. secondary or tertiary) (Sheppard et al. 2010), large quantities of domestic effluents are discharged to coastal and marine environments in the Arabian Gulf. These effluents are characterized by high-suspended solids and high loads of nutrients such as ammonia, nitrates and phosphates (Naser, 2011a). Sewage effluents are generally accompanied by biological and chemical pollutants, including pathogen microorganisms and heavy metals (Shatti and Abdullah, 1999). Bioaccumulation and biomagnification of pathogenic organisms and chem‐ ical contaminants due to sewage discharges affect the quality of human food and subsequently pose threat to human health.

Shallow subtidal areas and semi-enclosed embayments are the receiving environments for most of the sewage discharges in the Arabian Gulf, which can cause localized eutrophication, nutrient enrichment and oxygen depletion. Kuwait Bay in Kuwait and Tubli Bay in Bahrain have witnessed several eutrophication conditions and fish mortality phenomena due to excessive sewage discharges (Al-Ansi et al., 2002; Glibert et al., 2002). Naser (2013b) studied crustacean assemblages influenced by sewage discharges from a major treatment station in Bahrain. The study reported a reduction in biodiversity, richness and evenness of crustaceans reflecting severe habitat degradation in the nearby marine environment. Additionally, influenced areas were characterized by marked increase in organic enrichment, mainly ammonia and phosphate.

#### *3.2.5. Oil pollution*

**Figure 5.** Marine organisms at the proximities of desalination plants are influenced by chemical, physical and thermal pollution. Reduced levels of diversity and abundance of macrobenthos were recorded adjacent the outlet of this MSF

Sewage effluents are considered one of the most common anthropogenic disturbances of marine ecosystems in the Arabian Gulf. Despite high standards of sewage treatment (i.e. secondary or tertiary) (Sheppard et al. 2010), large quantities of domestic effluents are discharged to coastal and marine environments in the Arabian Gulf. These effluents are characterized by high-suspended solids and high loads of nutrients such as ammonia, nitrates and phosphates (Naser, 2011a). Sewage effluents are generally accompanied by biological and chemical pollutants, including pathogen microorganisms and heavy metals (Shatti and Abdullah, 1999). Bioaccumulation and biomagnification of pathogenic organisms and chem‐ ical contaminants due to sewage discharges affect the quality of human food and subsequently

Shallow subtidal areas and semi-enclosed embayments are the receiving environments for most of the sewage discharges in the Arabian Gulf, which can cause localized eutrophication, nutrient enrichment and oxygen depletion. Kuwait Bay in Kuwait and Tubli Bay in Bahrain have witnessed several eutrophication conditions and fish mortality phenomena due to excessive sewage discharges (Al-Ansi et al., 2002; Glibert et al., 2002). Naser (2013b) studied crustacean assemblages influenced by sewage discharges from a major treatment station in Bahrain. The study reported a reduction in biodiversity, richness and evenness of crustaceans

desalination plant along the eastern coastline of Bahrain (2012).

*3.2.4. Sewage discharges*

308 Biodiversity - The Dynamic Balance of the Planet

pose threat to human health.

The Arabian Gulf is considered the largest reserve of oil in the world (Literathy et al., 2002). Consequently, coastal and marine environments in the Arabian Gulf are under permanent threat from oil related pollution. Oil exploration, production, and transport have been major contributors to pollution in the Arabian Gulf. Sources of oil spills in the Arabian Gulf include offshore oil wells, underwater pipelines, oil tanker incidents, oil terminals, loading and handling operations, weathered oil and tar balls, illegal dumping of ballast water, and military activities (Sale et al., 2010).

The Arabian Gulf has been a scene for major oil spill incidents in the world. Bahrain experi‐ enced one of the earliest major oil spills in the Arabian Gulf in 1980. A large oil slick (20,000 barrels) invaded the north and west coasts of Bahrain causing severe ecological and economical damages (Brown and James, 1985). This major incident was a precursor for establishing the first governmental authority concerned with the protection of environment in Bahrain in 1980; namely, the Environmental Protection Committee (EPC). The most notorious oil spill reported in the Arabian Gulf occurred during the 1991 Gulf War. An estimated 10.8 million barrels of oil were spilled in the Arabian Gulf waters (Massoud et al., 1998).

Oil pollution adversely affects marine ecosystems by reducing photosynthetic rates in phytoplankton and marine algae, accumulating toxic chemicals in several benthic organisms, and contaminating human food chains with carcinogenic substances. Seabirds and intertidal waders are predominantly vulnerable to oil pollution. For instance, several seabirds suffered severe mortality (22−50%) during the 1991 oil spill in the Arabian Gulf (Evans et al., 1993). Environmental consequences of long-term chronic oil pollution include degradation of sensitive ecosystems such as seagrass bed, coral reefs and mangroves, which may subsequently lead to decline in fish stocks and other renewable marine resources.
