Seagrass habitats in the Arabian Gulf constitute a critical marine resource in the region, sustaining a high primary production, harbouring a high biodiversity of associated plant and animal species, and serving as important nursery grounds for penaeid shrimps, pearl oysters and various other marine organisms. The extreme environmental conditions in the Arabian Gulf, with major seasonal variations in water temperature and salinity, are tolerated by only three opportunistic seagrass species (Halodule uninervis, Halophila stipulacea and H. ovalis). Approximately 7,000 km2 of seagrass habitat has been mapped in the Arabian Gulf to date, with particularly extensive meadows in the coastal waters of the United Arab Emirates, Bahrain and Qatar. This area also sustains the world's second largest population of approximately 5800 dugongs, which feed almost exclusively on seagrasses. Meanwhile, massive land-reclamation projects and rapid industrial developments (including power- and desalination plants) are posing an unprecedented threat to seagrass habitats in this region. This paper provides a detailed overview of the known distribution of seagrass habitats in the Arabian Gulf and their tolerance thresholds for temperature, salinity, turbidity and sedimentation. The paper concludes with a summary of the main threats to seagrasses in the Gulf and recommendations for their conservation and management.
The ecological importance of seagrasses in the Arabian Gulf has been widely acknowledged (Sheppard et al., 1992; Price, 1998; Jones et al., 2002). Several Gulf States have vast areas with shallow depths suitable for seagrass growth. Seagrass habitats are recognized and designated as a critical marine resource in the Gulf, sustaining high primary production, harbouring high biodiversity of associated species, and serving as important nursery grounds for penaeid shrimps, pearl oysters and other organisms of importance to the Gulf's commercial and artisanal fisheries (Sheppard et al., 1992; Jones et al., 2002).
Seagrasses in the Gulf play a major role as food for threatened species such as green turtles (Chelonia mydas - Endangered) and dugongs (Dugong dugon - Vulnerable) (Preen, 2004). With their extensive root systems, seagrasses also play a crucial role in the stabilisation of the nearshore seabed (esp. mobile sands) against wave action and other erosional forces (Jones et al., 2002; Erftemeijer et al., 2006). Seagrasses are a major source for detrital food chains, which provide an indirect source of food for many marine organisms. Several authors reported significantly higher densities and biomass of benthic fauna in seagrass beds relative to unvegetated sand or mud (Orth et al., 1984; Coles and McCain, 1990). The species diversity of benthic fauna associated with seagrass beds in the Gulf has been reported between 530 (Basson et al., 1977) and 835 species (Coles and McCain, 1990). About 9% of the Gulf's faunal taxa (at least 48 species, mostly molluscs) are endemic to seagrass meadows (Basson et al., 1977). Approximate figures from Tarut Bay (410 km2) suggest the seagrass beds in this bay support the production of ∼4 million kg of fish and shrimp annually worth $22 million US (Price et al., 1993).
There are very few detailed studies on the tolerance thresholds, natural dynamics and post-disturbance recovery of seagrasses in the Gulf and published data on their current distribution and extent remain scarce (Price and Coles, 1982; Phillips, 2003a). Recent massive land reclamation schemes and large power- and desalination plants, however, have given rise to concern about potential impacts upon seagrasses in the Gulf (Butler, 2005; Salahuddin, 2006; Sheppard et al., 2010).
A series of recent environmental baseline surveys and impact studies provided opportunities to locally map and investigate the distribution and status of several extensive seagrass areas in the United Arab Emirates, Qatar, Bahrain, Kuwait and Saudi Arabia to add to existing information (Phillips, 2003a). This paper aims to provide: (1) an update on the known distribution and area cover of seagrass habitats in the Arabian Gulf, (2) a review of the known tolerance thresholds to key environmental parameters for different seagrass species occurring in the Gulf, (3) a summary of the main threats to seagrass habitats in the Gulf, and (4) recommendations for their conservation and management.
Seagrasses are widely distributed along the shores of all countries surrounding the Arabian Gulf, except Kuwait (limited) and Iraq (absent). Dense seagrass beds are usually confined to sandy and muddy substrates in nearshore waters shallower than ∼10 m. Further offshore they appear to be patchy and less prevalent, at least along the Gulf coast of Saudi Arabia. In southeast Bahrain, however, they are more extensive even in (shallow, <10 m) offshore areas (Vousden, 1986; Phillips, 2003b). Maximum depth penetration of seagrasses in the Gulf has not been thoroughly assessed, but available records reveal growth of individual plants to depths of at least 22 m (Qatar, personal observation, 2005; Delft Hydraulics, 2005a; URS, 2008).
Phillips (2003a) provided the first comprehensive overview of seagrass distribution and extent in the Arabian Gulf. Recent baseline surveys and environmental impact assessments have added at least 12 areas not previously recorded. By far the largest areas of seagrass habitat occur in the Abu Dhabi emirate (Phillips et al., 2002; Emirates Heritage Club, 2004; Howari et al., 2009). Other significant seagrass areas in the UAE include Shuwayhat (Ruwais), Das Island, Mubarraz Island, Marrawah (incl. Al Hail), Al Dhabayah, Khor al Beidah (Umm al Quwain), Al Taweelah and Jebel Ali (Delft Hydraulics, 2001, 2005b, 2005c, 2007b). Some of the best seagrass areas in Bahrain include Tarut Bay, Dawhat Zaium and Dawhat Salwah (Vousden, 1986). Qatar probably has extensive seagrass areas, but apart from Fasht al Arif (at Messaieed), which features several hundred hectares of dense meadows, these have not yet been documented. Recent surveys by Halcrow indicate significant (though sometimes patchy) meadows at Al Khor and Doha (David Medio, pers. comm. 2009). In Saudi Arabia, extensive meadows occur between Safaniya and Manifa, in Musallamiyah and south of Abu Ali, and in the Gulf of Bahrain (Price and Coles, 1992). Distribution of seagrasses in Kuwait is limited, but recent studies revealed significant meadows at Dbaiyah and Nuwaiseeb (Shuail, 2008a,b). There are no published records of seagrasses in Iraq. Seagrasses may be widely distributed along the shoreline of Iran (though probably not extensive, due to a limited extent of shallow areas), but this is poorly documented (Maghsoodloo and Eghtesadi, 2008).
Three species of seagrass occur in the Gulf: Halodule uninervis (most widely distributed), Halophila stipulacea (less common, but forming dense meadows in some areas) and Halophila ovalis (rarely forming dense monospecific meadows) (den Hartog, 1970). These three species form either monospecific or mixed-species meadows in the Gulf. At least two species (H. uninervis and H. ovalis) were recorded in Iran (Maghsoodloo and Eghtesadi, 2008). There are unconfirmed records of other seagrass species in the Gulf: Halodule wrightii and Syringodium isoetifolium (Den Hartog, 1970), some of which may actually refer to observations in the Arabian Sea rather than the Arabian Gulf, as confirmed by recent records of Syringodium isoetifolium in Oman (Wilson, 2000).
Table 1 gives an overview of all known seagrass habitats in the Arabian Gulf mapped to date. The total extent in the Gulf is estimated to range between 6790–7320 km2 (sum of mapped areas). This is likely to be an underestimate, as there are large areas that have not yet been surveyed. Following the approach of Green and Short (2003), i.e. by taking a certain percentage of available shallow areas (here 50% of areas <5 m) calculated from bathymetric maps using GIS, a maximum estimate of the total extent of seagrass habitat in the Gulf would be approx. 10,000 km2 or ∼6% of the global total (Green and Short, 2003).
The Arabian Gulf supports a large population of dugongs (Dugong dugon), a species listed by IUCN as vulnerable to extinction (Preen, 2004). The total population in the Gulf has been estimated to consist of some 5800 animals, making this the world's most important area for dugongs after Australia (Preen, 2004). The most important foraging habitats for dugongs in the Gulf are on either side of Bahrain, particularly around the Hawar Islands, off Saudi Arabia between Qatar and the UAE, and off Abu Dhabi (Preen, 2004). Several parts of the Saudi Arabian Gulf coast west of Bahrain have recently been recommended by UNEP as priority areas for conservation of dugongs, including (1) Qurayyah (north western section of Gulf of Salwa), (2) Saudi-Bahrain (west of Bahrain, between the Causeway and Ras al Barr), (3) southern section of Gulf of Salwa, and (4) Tarut Bay (east to Fasht Farim (Bahrain) and south to Al Khobar) (Marsh et al., 2002). Dugongs are known to feed almost exclusively on seagrasses with a preference for smaller pioneering species such as Halodule and Halophila spp. (Erftemeijer et al., 1993).
Significant populations of herbivorous Green Turtles (Chelonia mydas) also feed on seagrasses in the Gulf. Das (2007) reported a total population of 5500–7500 foraging green and hawksbill turtles in Abu Dhabi waters based on aerial surveys in 2004. More than 70% of these turtles were observed within the Marrawah Marine Protected Area. Some 1000 females year−1 nest on Karan and Jana Islands off the Saudi coast (Pilcher, 2000), and another 4000 females year−1 nest outside of the Gulf at Ras Al-Hadd, Oman (Ross and Barwani, 1982).
Seagrasses in the Arabian Gulf are subject to extreme natural variations in water temperature (locally ranging from 10 to 39°C) and salinity (38 to 70 ppt, Price et al., 1993). Not all seagrass species can tolerate such ranges of temperature and salinity, which explains why only three of the more than 50 species recorded worldwide manage to survive in the Gulf. These three (Halodule uninervis, Halophila stipulacea and H. ovalis) are known to be opportunistic, pioneering species with a broad tolerance and ability to recover rapidly (Den Hartog, 1970). Seagrass growth and health is controlled by a range of environmental variables. Here, we review available information on the sensitivity of seagrasses for salinity, temperature, turbidity and sedimentation. These constitute some of the most relevant abiotic variables for impact assessments of planned coastal developments such as port construction, dredging, land reclamation and construction of power- and desalination plants. Other factors, including oil, chlorine, hypoxnia, anoxia and eutrophication, can also impact seagrasses but were not included in this review.
Tolerance to salinity is an essential requirement for seagrasses. Seagrasses may encounter a wide range of salinities in the shallow coastal environments in which they occur. The optimum salinity and tolerance range for salinity vary among seagrass species (Lirman and Cropper, 2003). In general, experimental results show that a wide range of salinities may be tolerated by seagrasses for very short periods but long-term tolerances are narrower (Hillman et al., 1989). Complete restriction of seagrass growth by high salinity, as suggested in an earlier study in the Gulf (Evans et al., 1973), was not supported by Price and Coles (1992) who found no significant correlation between salinity and the cover and biomass of seagrasses in an intensive survey of 52 sites along the Arabian coastline. Halodule uninervis is the most broadly euryhaline of the three seagrass species in the Gulf. Because of its very broad tolerance to salinity, it can occupy shallow areas subject to extreme salinity ranges (Hillman et al., 1989). In Dawhat Zalum and parts of the Gulf of Salwah, this species was found thriving at salinities of at least 62‰ (Basson et al., 1977). In the hypersaline coastal lagoon of Al Qair in Saudi Arabia, healthy seagrass beds dominated by Halodule uninervis and Halophila stipulacea were found at salinities of 55–59 ‰ (Delft Hydraulics, 2007a). In Shark Bay (Australia), Halodule uninervis was observed to grow under ambient salinities ranging from 48 to 62‰ (Masini et al., 2001). In a recent study in Florida by Koch et al. (2007) on the effect of hypersalinity on tropical seagrass species, Halodule wrightii was found to be able to tolerate salinities up to 65 ‰. It remains a challenge to derive accurate salinity thresholds for seagrasses in the Gulf. Some EIA reports suggest that at salinities greater than 58‰ seagrass growth in the Gulf is reduced, while at salinities of more than 67‰, a location is not suitable for any seagrass species. Based on the overview above, these are probably reasonable salinity thresholds to work with in EIA studies.
The temperature tolerance of seagrasses varies with geographical latitude. Tropical and subtropical species do not tolerate cold temperatures and are only slightly more tolerant of extended periods of high temperatures than temperate species (Hillman et al., 1989). Den Hartog (1970) recorded a lower temperature limit for Halophila ovalis of 10°C. Intertidal seagrass populations that are exposed to air at low tides show greater tolerance of high temperatures than those occurring at permanently submerged sites (McMillan, 1984). Among tropical seagrass genera, Halodule shows the greatest heat tolerance (McMillan, 1984) and H. wrightii beds in Florida are able to survive temperatures to 39.4°C. Optimal temperatures for most tropical seagrass species lie between 25 and 37°C (Lee et al., 2007). Seagrass growth is reduced at temperatures above 37°C and conditions above 40°C for an extended time are considered lethal. Based on the overview above, these are probably reasonable temperature thresholds to work with in EIA studies.
Light is one of the key environmental resources imperative for the growth and survival of seagrasses. Reduction in light due to turbidity has been identified as a major cause of seagrass loss worldwide (Green and Short, 2003). The amount of light that reaches a seagrass leaf is determined by natural water colour, total suspended solids (TSS), phytoplankton concentration and leaf epiphyte cover. There are various reports of (sub)lethal effects on seagrasses due to prolonged exposure to high turbidity and siltation associated with dredging (Erftemeijer and Lewis, 2006). Indicators of light stress in seagrasses may include changes in below-ground biomass, leaf chlorophyll a content, carbohydrate contents of rhizomes and various photosynthetic parameters (Coles and McKenzie, 2004; Ochieng, 2008). Laboratory experiments indicate that some seagrasses can survive in light intensities below their minimum requirements for periods ranging from four weeks to several months. Since light reduction by suspended sediment depends on its grain-size distribution, TSS may not constitute the most practical thresholds during dredging operations. Thresholds more relevant to seagrasses are those expressed as ‰ of surface irradiance (SI) that reaches the bottom as a measure of the minimum amount of light required by the seagrass plants to survive. Published literature values for minimum light requirements of Halodule species range from 14 to 30% of SI, while for Halophila species values are between 5 and 9% SI (Erftemeijer and Lewis, 2006). For EIA studies, it would be fair to assume that seagrass growth is unaffected at higher light levels, growth conditions are sub-optimal at light levels within these ranges, and mortality will occur if light levels are sustained below these ranges for extended periods of time (weeks).
Several studies document deterioration of seagrass meadows by smothering due to excessive sedimentation. Seagrasses can respond to fluctuations in sediment depth by modifying their vertical growth, but there are limits to the level of sedimentation they can tolerate (Marba and Duarte, 1994). Vermaat et al. (1997) reported deposition rates of 10–13 cm yr−1 as maximum threshold for seagrasses in the Philippines and Spain. Settlement of suspended material on seagrass leaves may interfere with photosynthesis and can be especially significant in low wave energy environments and when epiphytes are abundant. Field experiments have shown significant species-specific differences in the duration that seagrasses can tolerate high rates of sedimentation, with larger climax species (e.g. Posidonia oceanica) surviving as much as 15 cm of sediment for periods up to 200 days (Manzanera et al., 1995), while smaller opportunistic species (e.g. Cymodocea nodosa) showed mass mortality after burial with 5 cm of sediment within 35 days (Marba and Duarte, 1994). Experiments in the Philippines with Halophila ovalis also revealed a critical threshold for sedimentation of 5 cm per year (Vermaat et al., 1997). This would probably be a reasonable sedimentation threshold to use in EIA studies (for all three species).
The past decade has seen unprecedented changes in the Arabian Gulf region. Rapid industrial development, massive land reclamation schemes, residential and tourism developments have caused widespread loss and degradation of benthic habitats, declining biological diversity, over-exploited fish-stocks, along with algal blooms and marine pollution (Sheppard et al., 2010). The large scale of the activities compared to the relatively shallow and small size of the water body is a particularly important issue, as is the unprecedented speed of these developments. Seagrass habitats in the Gulf have undoubtedly suffered as a consequence, though there are no published reports on the scale of these impacts or rates of decline.
Dredging and land reclamation
Dredging and coastal infilling arguably represent one of the greatest environmental threats to seagrasses, particularly in the Gulf region where more than 40% of the coastline has now been modified and developed (Sheppard and Price, 1991). Substantial sea bottom dredging for material and its deposition in shallow water to extend land or to form a basis for huge developments, directly removes large areas of shallow, productive benthic habitat such as seagrass beds. In addition to this direct footprint, dredging may cause substantial increases in turbidity and sedimentation and changes to water flow and water quality (Erftemeijer and Lewis, 2006).
Large-scale, iconic coastal real-estate developments in the Gulf include ‘The World’ and ‘Palm Islands’ in Dubai, UAE, ‘The Pearl’ in Qatar, ‘Al Khaleej’ in Half Moon Bay, Saudi Arabia, ‘Pearl City’ in Kuwait, and the ‘Durrat Al Bahrain’, ‘Amwaj’, and ‘Dyar Al Muharraq’ developments in Bahrain (De Jong et al., 2005; Al-Kalali and Subasing, 2008; Burt et al., 2012, in press). The combined direct footprint of these developments is in the order of several hundreds of square kilometres. In addition, these reclamations require the dredging of large quantities of sand from borrow areas, which implies the potential for additional impacts on seagrass habitats away from the actual reclamation areas. Palm Jebel Ali, for example, itself covering an area of about 25 km2, required dredging of 117 million m3 of seafloor sediments from nearby borrow areas (Delft Hydraulics, 2005c; Fugro, 2006). Construction of the Saudi-Bahrain causeway involved dredging of c. 60 million m3. The proposed Dubai Waterfront, itself covering an area of about 40 km2, requires the dredging of c. 325 million m3 of sand from borrow areas.
There are relatively few published quantitative reports on losses of seagrasses due to dredging or land reclamations in the Gulf (Erftemeijer and Lewis, 2006). In Bahrain, extensive areas of coral and seagrass habitat were affected by reclamation and dredging (Al-Madany et al., 1991) with an estimated loss of 1,020 ha of seagrass habitat from the Fasht-al-Adhm area between 1985 and 1992 (Zainal et al., 1993). Analysis of satellite imagery of Tarut Bay (Saudi Arabia) revealed that 5,416 ha and 1,050 ha of coastal habitat (including vast areas of seagrass) had been reclaimed between 1973–1985 and 1985–1990 respectively (Al-Thukair et al., 1995). Recent port expansions at Ras Laffan in Qatar (totalling c. 36 km2) are likely to have affected extensive areas of seagrass habitat in that area (Richer, 2008). Construction of the Bahrain–Saudi Arabia (King Fahad) Causeway (direct footprint 2 km2 and involving several million m3 of fill) has had major impacts on the marine ecology of the region, including seagrass beds (Price et al., 1984). Similarly, sediment spill from dredging and reclamation during the construction of the new Qatar-Bahrain causeway is expected to affect some 4–5 km2 of seagrass beds (COWI, 2008). Construction of causeways in the Gulf may also lead to habitat fragmentation for dugongs and turtles by reducing access to critically important foraging grounds (Sheppard et al., 2010).
Power and desalination plants
The Arabian Gulf contains the highest concentration of desalination plants in the world, with a total seawater desalination capacity of approximately 11 million m3 per day, yielding some 60 percent of the region's water needs (Latteman and Höpner, 2008). The main producers in the Gulf region are the United Arab Emirates, Saudi Arabia and Kuwait. Most desalination (90%) in the Gulf region is met by thermal processes (MSF: multi-stage flash; MED: multi effect distillation), combining seawater production with power generation, but there are also several Reverse Osmosis (RO) plants. Thermal desalination requires a lot of energy, and MSF plants are therefore always associated with a power plant. Discharge water of both MSF and RO plants has a higher salinity than the source water. In MSF and MED plants, the temperature of the discharge water is also elevated (+5 to 15°C above ambient) (Latteman and Höpner, 2008). The discharge water consists of not only warm water, condensate, rejected distillate and brine but also those effluents related to such items as antifoams, antiscalants, cleaning acids, pre-treatment and post-treatment chemicals with potentially significant consequences for the environment (Areiqat and Mohamed, 2005). Little is known of the cumulative effects of multiple power- and desalination plants, but it is expected to become an issue of major concern in the relatively confined and shallow Arabian Gulf region with its ever-increasing number of (large) desalination plants (Sheppard et al., 2010).
Oil exploration and spills
Each year, approximately 200,000 tonnes of sea freight are transported through the Straits, including 2,195,000 barrels of crude oil and 509,000 barrels of refined oil per day from the UAE alone, en route to the USA, Western Europe, Africa and Asia (OPEC, 2005). The exploration, processing and transport (∼25,000 tanker movements per year) of these massive quantities of oil in the Gulf represent a major risk for oil spills and oil pollution (Al-Azab et al., 2005). About 2 million barrels of oil are spilled annually from the routine discharge of dirty ballast waters and tank washing (Sheppard et al., 2010). Oil spills can cause significant adverse impacts on seagrass ecosystems, in particular on the associated benthic fauna (Zieman et al., 1984). In 1991, the Gulf War led to a massive oil spill, smothering >700 km of coastline from southern Kuwait to Abu Ali Island with oil and tar, causing major impacts on coastal ecosystems (WCMC, 2005; Munawar et al., 2002). Experiments assessing the toxicity of Kuwait crude oil on seagrasses of the Gulf confirmed field observations that the Gulf War oil spill primarily impacted intertidal communities rather than the seagrasses themselves (Durako et al., 1993; Kenworthy et al., 1993).
Conservation and Management
Krupp (2002) listed 52 existing or proposed coastal and marine protected areas in the Gulf region. At least 19 of these are known to incorporate seagrass meadows (Table 2), although the presence of seagrasses themselves has rarely been a primary reason for their establishment (Krupp, 2002). Protection of seagrasses within MPA's alone is not enough, and huge challenges remain to prevent major losses of seagrasses throughout the Gulf due to the various threats outlined in the previous section. National environmental legislation and international and regional agreements, including the Kuwait Action Plan coordinated by the Regional Organisation for the Protection of the Marine Environment (ROPME), offer a framework for protection of marine habitats in the Gulf (including seagrasses), although their enforcement and implementation is often inadequate.
Environmental impact assessments should take note of recent reviews and guidelines on how to minimize environmental impacts from dredging (Erftemeijer and Lewis, 2006; PIANC, 2010) and desalination plants (Latteman and Höpner, 2008). Oil spill response plans and sensitivity mapping could also offer opportunities for seagrass protection, although there is little mention of seagrasses in some existing oil spill sensitivity maps in the region (e.g. for Kuwait and Qatar). Conservation measures and plans for dugongs and turtles also offer potential benefits for seagrass protection in the Gulf. An example is the 2007 Dugong Memorandum of Understanding (signed by UAE, Iran and Bahrain) designed to provide international protection to the dugong and its habitat (UNEP/CMS, 2007).
Not all loss of seagrass habitat in the Arabian Gulf is permanent or irreversible, as there is potential for recovery once environmental conditions return back to their original state (e.g. upon cessation of a dredging operation). Recovery from significant disturbances may take several years (depending on the scale of impact), which is relatively fast owing to the opportunistic character of the three seagrass species in the Gulf. Seagrasses may also colonise new areas created during land reclamation. For example, spontaneous colonisation by Halodule uninervis of newly created subtidal areas was reported at the West Bay Lagoon area in Doha (Jones et. al., 2007). ‘Pearl City’ in Kuwait has generated many new ecosystem services and benefits, which may offset dredging damage. Seagrasses also colonised shallow areas within Palm Jebel Ali, which is now further enhanced through transplantation (Katakura et al., 2008).
To document such losses and gains, there is an urgent need for monitoring of seagrass habitats in the Gulf, preferably at different spatial and temporal scales. Establishment of monitoring sites as part of SeagrassWatch (Shuail, 2008b) or SeagrassNet would be an encouraging start. There is also an urgent need to fill research gaps on tolerance thresholds, interactive effects between multiple stressors and impacts of seagrass loss on dugong and green turtle populations and on fisheries. Data from research undertaken by private companies for large-scale developers and oil and gas clients should be made publicly available.
Some 7000 km2 estimated total of 10,000 km2 (or ∼6% of the global total) of seagrass habitat has been mapped in the Arabian Gulf to date, representing a critical resource that serves as a primary food source for the world's second largest population of dugongs and green turtles and plays a vital role in supporting the region's productive fisheries. Only 3 seagrass species (Halodule uninervis, Halophila ovalis and H. stipulacea) occur in the Gulf. Tolerance limits of these species for temperature, salinity, turbidity and sedimentation indicate that they are well-adapted to the harsh environmental conditions in the Gulf, characterised by extreme natural fluctuations in temperature and salinity. Recent decades have seen an unprecedented increase in the threats to seagrass habitats in the Gulf, in particular from large-scale dredge and fill operations, desalination plants and other industrial developments (incl. oil). Marine protected areas, existing legislative and regulatory frameworks and their enforcement presently appear inadequate to effectively address these threats. There is an urgent need for monitoring of seagrass habitats in the Gulf to better understand their natural dynamics and resilience and to document losses and recovery. Ultimately, one of the main challenges to be addressed in the Gulf region is the fact that the cumulative impacts of multiple desalination plants and multiple dredge and fill projects are likely to be greater than the effects of any one development alone (Sheppard et al., 2010). Until this issue is addressed in a concerted manner within and between the various Gulf states, implementation of single case-by-case impact assessments may do little to stem the degradation and loss of seagrass habitats in the Gulf.
The authors would like to thank David Medio (Halcrow) for providing information on seagrasses in Qatar, Fred Short for inviting PE to prepare this work for a regional IUCN Red List Assessment workshop in the Philippines (March 2008) and Deltares for supporting PE to present this paper at the GULF II Conference “The State of the Gulf Ecosystem: Functioning and Services” in Kuwait (February, 2011).