Preliminary calculations indicate that western Gulf intertidal mud and sand flat habitats such as those found in Kuwait may contribute some 30 percent of the gross marine productivity for this state, more than double that of any other intertidal biotope. Mud flats are dominated by a microbial mat system; recent application of the stable isotope ratio technique confirms a link between mat production and commercial fish and shrimp species. These findings demonstrate the importance of intertidal productivity so that dredging and coastal reclamation represent one of the most serious impacts on the Gulf environment. In addition, Gulf fish stocks are now fully exploited and many Gulf countries are placing further stress on coastal ecosystems through the development of aquaculture.
Most of these countries now have coastal management plans with zoning of areas for conservation, recreation and development and future planning prioritization should ensure sustainability of marine biodiversity, fisheries, aquaculture, aesthetic and recreational values for coastal habitats during development. Recent coastal construction projects in Qatar, Bahrain, Saudi Arabia and Kuwait demonstrate that even within development zones it is possible to mitigate impact and even expand areas of marine productivity. Key factors are multidisciplinary approaches to design, which promote good water circulation, avoid stagnation, prevent salinity rise due to evaporation and sustain water of bathing quality. It is suggested that artifically created lagoons and waterways could be managed to provide nursery areas suitable for fishery stock enhancement.
Attempts have been made to quantify the distribution and area of important productive marine habitats using remote sensing techniques (Vousden, 1987; Kwarteng and Al-Ajmi, 1997; Turner et al., 1999) and results have been used successfully in integrated coastal management (ICM) plans to designate sensitive areas for protection status. As many of these habitats (sea grass beds, algal beds, corals, mangroves, mudflats) have been ascribed values for gross primary production it is now possible, albeit crudely, to quantify the contribution made by each habitat to overall marine production, providing a further estimate of the significance of habitats for ICM (Jones et al., 2002a). Using this approach the mudflats in Kuwait Bay are revealed to be one of the most productive of intertidal habitats. The stable isotope (δ13C) technique used to measure the signature of all major sources of primary productivity on mudflats indicates that all trophic levels, including penaeid shrimp and carnivorous shellfish and fish are supported by primary production from microbial mat and benthic diatom complexes (Jones et al., 2002b). Comparison between these Gulf intertidal benthic soft sediment communities (Coles and McCain, 1990; Al-Zaidan, 2002) and those of tropical shores elsewhere (Broom, 1982; Swennen et al., 1982; Nandi and Choudhury, 1983) reveals that the former have similar species richness and abundances. Macrofaunal biomass for Kuwait and Saudi Arabia are also amongst the highest recorded throughout the world (Al-Zaidan, 2002).
Apart from present anthropogenic impacts of oil and industrial pollution upon these highly productive shores there are new and rapidly expanding impacts caused by leisure, recreation, tourism and aquaculture. Rapid modification of the coastline and existing marine habitats to create marinas, artificial lagoons, islands, canals and beach complexes is occurring throughout the Gulf. These impacts, together with reclamation are now considered to be the most important threats to the future sustainability of the Gulf ecosystem (Khan et al., 2002). In view of the above recent recognition of the important contribution by coastal habitats to Gulf food webs, it is imperative that full multi disciplinary studies are conducted into the potential impact of any such developments.
This paper reviews the impacts of some recent coastal developments and describes the design and development of a successful artificial lagoon. This provides a case study to demonstrate the potential for enhancement of coastal marine productivity, while at the same time functioning to support the expanding recreational and tourist industry. As information is sparse (Bishop, 2002) the current status of the rapidly growing Gulf aquaculture industry is briefly reviewed, together with its potential and actual impacts. Stock enhancement is suggested in mitigation for both types of impact, by using artificially created waterways as nursery areas for cultured local commercial species of fish and shellfish.
Impacts of aquaculture on the environment
Countries bordering the Arabian Gulf imported U.S. $139.7 million dollars, more fish products in 1999 than they exported (FAO, 2001), representing 142.4 thousand tons. Of this value, $57.8 million dollars represented fish oils and meal, leaving about $82 million dollars of imported fishery products for direct human consumption. Among the Gulf countries, only Bahrain enjoyed a notable surplus of fishery exports over imports, with those of the United Arab Emirates (UAE) being only slightly in favor of exports. The Gulf's fish stocks are either fully exploited or over exploited, so aquaculture is the only alternative to increasing landings in order to close the gap between consumption and production. Human population growth per annum varies between 1.4% for Iran and 3% for Saudi Arabia (Khan, 2002), so demand for fish will continue to increase.
Aquaculture research in the Gulf began in the late 1970s (Higuchi, 1978), and commercial production began in Kuwait in 1992 (Bishop, 2002). There are four aspects of commercial aquaculture in the Gulf: 1) production of postlarval shrimp or fingerling fish, 2) releasing juveniles to supplement wild stocks, 3) grow-out production, and 4) testing suitability of new species for culture. Iran's shrimp hatcheries produced about 1 × 109 postlarval shrimp (mostly Fenneropenaeus indicus) in 2002 to supply the rapidly growing shrimp aquaculture industry along Iran's coastal provinces and to stock selected nursery grounds (Sakouri, 2003). In 2002, 2,640 ha of culture ponds produced 6,000 t of shrimp, a decrease of 21% from the previous year due to White Spot Syndrome. The industry continues to expand rapidly with 26,000 ha either ready for production or under construction (Sakouri, 2003). Since 1995, Iran's stock enhancement programme has released about 2 to 5 × 106 postlarvae F. indicus annually on nursery ground habitat in the southern provinces, but the benefit of this strategy has not been demonstrated (Sakouri, 2003).
Iran's marine fish culture is at present in the experimental stage. Species being considered for culture include the Silver Pomfret (Pampus argenteus), Milkfish (Chanos chanos), Dolphinfish (Coryphaena hippurus), Asian Seabass (Lates calcarifer), rabbitfish (Siganus sp.), and Gildhead Seabream (Sparus aurata) (Sakouri, 2003). Research is also being conducted on brine shrimp (Artemia sp.), the pearl oyster (Pinctada radiata), and seaweeds (Gracilaria sp.) (Sakouri, 2003). Iran cultures freshwater species such as sturgeon, rainbow trout, carp, and a number of other warm-water species (Sakouri, 2003), but these are not considered here.
Encouraging breakthroughs with several aspects of the cultivation of the silver pomfret, Pampus argenteus, indicate that this species may join the list of Gulf indigenous species reared artificially. Almatar and Al-Abdul-Elah (1999) successfully fertilized stripped eggs from gillnetted males and females and raised the resulting larvae to juveniles approaching 100 mm body length. Hatchery techniques for this delicate species have now been refined (Al-Abdul-Elah et al., 2001, 2002; Cruz et al., 2003).
Fingerling marine fish species suitable for grow-out culture are produced in both Kuwait and Bahrain. Fingerling production in Kuwait in 2002 approached 2 × 106, with 1.2 × 106 Gilt-head Seabream and nearly 0.5 × 106 European Seabass (Dicentrarchus labrax). Both these species are of European origin. Other species being produced as juveniles for culture are indigenous to the Gulf and include Sobaity Seabream (Sparidentex hasta), Sha'm (Acanthopagrus latus), and Hamour grouper (Epinephelus coioides). Kuwait's fingerling production of the local species was fewer than 150,000 in 2002, but this number is expected to increase considerably in 2003. Bahrain has been very successful with producing fingerling Sobaity and current annual production is about 0.5 × 106 (Table 1). Most fingerling fin-fish are sold to grow-out facilities in either the UAE, Kuwait or, most recently, Oman.
Kuwait, Bahrain, and the United Arab Emirates are engaged in commercial grow-out production of fish. As of 2002, only Iran was engaged in shrimp culture, but shrimp culture operations are being planned for the UAE, Kuwait and probably in other Gulf countries. Saudi Arabia has several shrimp farms on the Red Sea coast south of Jeddah. Species under culture include local races of Penaeus monodon and F. indicus which are tolerant to high salinity levels (Kumlu and Jones, 1995; Bukhari et al., 1997). Although not present in the Gulf the latter species occurs in southern Iran, Yemen and southern Oman. Grow-out volume of fin-fish in Kuwait, Bahrain, and UAE are 35, 12, and 2,550 t (Table 1). The Gilt-head Seabream is the primary fish species being cultivated. Other species include the European Seabass, Sobaity, and Hamour. Additional species being considered for marine culture in Kuwait include the red talapia, three other species of seabass, 5 species of seabream, 5 species of snapper, 2 species of grouper, the milkfish, mullet, a pampano, and the cobia (Rachycentron canadum). Bahrain is focusing its efforts on just three species: the Sobaity Seabream, the rabbitfish (Siganus canaliculatus), and the Mangrove Snapper (Lutjanus argentimaculatus) (A.R. Shams, Directorate of Fisheries, Manama, Bahrain, pers. comm.). At 12 t, current production is modest (Table 1), but is expected to increase substantially with the acquisition of 15 sea cages in 2004.
As with marine aquaculture operations anywhere, environmental impacts fall into broad categories of introduced exotics, native species with altered genes, hybrids (which may be fertile), introduced diseases or parasites, build up of uneaten artificial feeds, additional loads of metabolites and other dissolved organics, and destruction of nursery habitat for pond construction.
Presently, the only exotic species being cultivated in the Gulf are Gilt-head Seabream and the European Seabass. These species have escaped from their caged environments, but whether they will establish breeding populations remains to be seen. Both species can survive and breed in Gulf conditions, but larval survival in the Gulf's high salinities (38 to > 45 ppt) is questionable (J. Bechara, Gulf International Aquaculture Co., Hawali, Kuwait, pers. comm.). Perhaps of more concern is the importation of Gulf species from other areas of the Indo Pacific Ocean. One aquaculture firm is planning to obtain fingerlings of Gulf species from Thailand. Escapees from cage culture operations could easily affect indigenous stocks through interbreeding. Additionally there is the threat of diseases specific for these species being introduced.
This is well documented for shrimp where, for example, introduction of Penaeus monodon from Asia to South America produced serious impacts as bacteroviral disease spread to local species. As the dominant Gulf shrimp Penaeus semisulcatus has shown poor survival in pond culture, attention should center on regional strains of F. indicus and Penaeus monodon which have enhanced tolerance to high salinity (Kumlu and Jones, 1995; Bukhari et al., 1997).
Because commercial aquaculture is relatively new to the region, cage culture operations are likely to be blamed for events that have not been recorded previously. The fish kill in Kuwait Bay is a case in point. In August and September 2001, about 3,000 tonnes of wild fish, mostly mullet, died from a pathogenic bacterium (Gilbert et al., 2002). After much speculation and many accusations, it was determined that the culprit was a bacterium, Streptococcus agalactiae. The source of this bacterium has not been identified, but aquaculture activities in Kuwait Bay were blamed. This pathogen has been identified in the Gilt-head Seabream imported from Greece, but not necessarily in the virulent form. Another source could be the imported fish feed fed. Sewage outfalls and ballast water discharge were other suggested sources of the pathogen. Aquaculture operations must ensure that the public is informed of their precautions to maintain a clean environment and avoid negative publicity as it is paramount to maintain customer demand by providing a high-quality product that does not harm the environment.
Aquaculture has a place in fisheries management of wild stocks. Gulland (1989) concluded that Kuwait could increase its landings by increasing the size at first capture. Usually, it is feasible for aquaculture operations to grow fish profitably to sizes of 2 kg or less, depending on species. If aquaculture can supply the smaller sizes for the general market, then fisheries could modify capture techniques to target larger specimens that would be uneconomical to cultivate. This would be particularly attractive for demersal species captured by fish trap such as hamour. This strategy is also applicable to the shrimp fishery, particularly with respect to jumbos, the larger size categories. Shrimp as jumbos command a much higher relative price on the international market, but growing large shrimp is rarely economical. If an abundant supply of small and medium size shrimp were available from culture operations, then wild stocks could be managed to harvest jumbos.
There is the further possibility of supplementing wild stocks by releasing cultured juveniles. This strategy has several potential shortcomings, however. Firstly, developers may convince government agencies that destruction of nursery habitat is permissible because juveniles can be raised artificially and released, so there is no longer a need for nursery habitat. Secondly, cultured fish will lack the genetic diversity of wild stocks. Thirdly, mortality of juveniles may be so high that resulting stock enhancement is insignificant and very costly. And there is the omnipresent danger of introducing disease or parasites to the wild stocks.
Although any loss of coastal habitat is undesirable, where this is unavoidable due to economic need, consideration should be given to the creation of artificial waterways and lagoons to replace lost nursery grounds. Water quality should be preserved so that artifically reared seed of local species of fish and shellfish can be stocked to enhance fisheries.
Impact of coastal developments
While most Gulf countries have coastal management plans zoning areas of conservation, recreation and development, few fully protected areas have as yet been finalised (Krupp, 2002). However, rapid expansion within development zones is currently occurring to accommodate new housing, recreation and tourist facilities. These include the creation of canals or waterways to supply beaches for individual houses, marinas, artificial lagoons and islands. Although these may have major deleterious impact upon intertidal and near shore marine productivity it is possible by using a multidisciplinary approach involving marine civil engineers, oceanographers architects and biologists to mitgate such impacts and even retain marine productivity. An example of poor design is seen in the recent development of a beach resort and marina on Hawar Island Bahrain (Young et al., 1999). Here a large area of productive intertidal and shallow subtidal habitat was enclosed within marina walls. Due to misalignment of the harbour walls the enclosed harbour acted as a settlement area for water born particulates. Initially the silt covered benthos was colonized by microbial mats, but as the marina trapped increasing amounts of drifting macroalgae bacterial action caused the whole system to become anoxic with the production of hydrogen sulphide and death of the microbial mat ecosystem. This resulted in the loss of a productive inshore habitat and a resort unusable by clients. Remedial action was to create a hydrodynamic model of the area using wind and tidal currents. This allowed engineers to identify and position openings in the marina walls and restore adequate circulation (Young et al., 1999).
The design for the proposed Al-Khiran Pearl City in Kuwait (Ealey et al., 2001) provides a further excellent example of the problems involved in the construction of waterways which extend the sea into the desert. Concerns over this type of coastal development are loss of existing habitat, provision of adequate flushing and water circulation, erosion and channel stability (Kana, 2002).
Impact assessment of the existing Khor system has revealed that this is hypersaline with a low benthic productivity, contains no endangered species and that the surrounding sabkha, where canals would be excavated, is also of high salinity and relatively unproductive. Provided that seepage of seawater from canals landward into the desert is prevented this project could ultimately produce some 200 km of new coastline with an area of seawater of over 40 km2 at a depth of 1 to 2 m. If marine sediments are used in the construction of beaches and to line the canals it may be expected that these waterways will be rapidly colonized by micro and macro biota producing a level of marine productivity in excess of that of the existing habitat. A hydrodynamic model has been constructed based on tidal and flushing measurements taken in the existing Khor Al-Ama. This model was constructed using the DIVAST numerical model (Falconer, 1992). Frictional effects due to depth of flow in different areas of the proposed water body are represented by the Colebrook White formulation (Henderson, 1996). Calibration was made using data on water level, flow, velocity and direction at four sites within the existing creek system collected by Kuwait Institute Scientific Research. The model was then used to derive flow conditions for further detailed hydrodynamic models based on 15 year and 25 year master plans for the phased expansion of the Al-Kiran City to its final capacity of over 100,000 inhabitants (Ealey et al., 2002). All canals and waterways are aligned to ensure adequate circulation even during neap tides with the aim of producing water quality of European bathing standards. Water quality is also the key to increased marine productivity and further research is required to ensure this is possible in such a large development (Kana, 2002). “Biological surveys of Phase I waterways and beaches completed in 2004 indicated a rapid recolonisation of marine biota” (Jones pers. obs. September 2004).
The success of artificially created water ways in the Gulf has been demonstrated in the design and implementation of the Al-Khaleej Village, Saudi Arabia (Ealey et al., 2001). In this case the design and construction of a 750,000 m2 inland tidal lagoon connected to Half Moon Bay was based on hydraulic tests on a physical model constructed in a 5 × 3.5 m tank at the Dept. of Civil Engineering, Imperial College, London. Dye injection of incoming flow was video recorded and the model altered to improve flushing characteristics (Ealey et al., 2001). Although Half Moon Bay is subjected to high salinities of 50 to 60%, surveys in 2001 indicated that colonization of the new benthos is occurring by the pioneering macroalgae Caulerpa sertularoides and Cladophora sp.
Other examples of coastal developments may be found in UAE such as Dubai and Sharjah. Often such developments exploit an existing low-lying area such as, for example, the Al Mamzar recreational area in Dubai, the Al Khan development in Sharjah, or the proposed development at Kalba, also in Sharjah. However, other examples exist that have been created entirely by dredging, such as the Dubai Marina, or the proposed development south of Mina Jebel Ali, also in Dubai.
The developments at Kalba and Jebel Ali have yet to be constructed, but those at Al Mamzar, Al Khan, and Dubai Marina have all been designed using the same numerical modelling techniques applied to the design of West Bay, as described in this paper. As far as is known, all developments are providing good standards of water quality. An additional benefit of the Al Khan development is the canal connecting it with the Khalid Lagoon, which had been extensively polluted for many years prior to construction of the Al Khan development. This canal features a set of one-way gates that allows the water to flow only from Al Khan to Khalid. The original objective of this canal was to promote the flushing of Al Khan, but it has also been a great benefit to Khalid Lagoon which has seen a dramatic improvement in its water quality since the opening of the canal.
Although many of the above coastal construction projects incorporate terrestrial and aquatic landscaping there is no information on the recolonisation of Gulf artificial waterways by marine biota and communities. The establishment of productive marine communities is critical to the use of these waterways as nursery grounds to support stock enhancement. Hence a study of the marine ecology of an artificial lagoon at West Bay, Qatar was initiated in 2002 and first results are reported below.
Materials and methods
Design of Doha West Bay lagoon
The original configuration of the Doha West Bay Lagoon, to the north of Doha on the east coast of Qatar is shown in Figure 1. The initial concept of the lagoon, to be excavated to a depth of 2.5 m and cover a total area of 6 km2 (Figure 2), was the product of a combination of socio-economic pressures and natural opportunity. However, refinement of this concept into a practical and functional design was achieved with the aid of numerical modeling tools.
Fundamental to a successful design is the need to maintain a high standard of water quality within the lagoon. This is commonly achieved by application of numerical models that compute current velocities and water levels, and resulting computed values are used to simulate the dispersion of pollutants, and their eventual removal from the lagoon. The flushing capability of the water body is the key to a guarantee of adequate water quality. The numerical model used for this study was Halcrow's in-house 2D (depth-integrated) modeling system (DAWN). The model is based on established finite difference methods that solve the equations of continuity and momentum to provide time stepping, grid based solutions of current velocity and water surface level. At each time step these computed values are used to predict the transport and diffusion of pollutants within the water column. The changes at each time step are then integrated from a defined initial condition to provide predictions at given points in time. The technique is to assume an initial condition in which the water body is uniformly filled with an imaginary non-decaying tracer. The model then simulates the flushing of the tracer from the lagoon under the natural effects of tide and currents. The flushing capability of the lagoon is judged by reference to model results presented as contour maps showing the percentage of the initial concentration still remaining. Unfortunately there was little published information in the literature to inform this judgment, and the process was therefore largely intuitive. The aim was to achieve a retention period of less than two weeks. The model was set up as a two-grid system (Figure 1). A 100 m primary grid was set up centred on the lagoon and covering overall an area 18 by 15 km, with a detailed 20 m grid to represent the area of the lagoon. The primary model was used to simulate the coastal flows, and thus to generate a set of boundary values with which to drive the detailed lagoon model.
Unless a through flow can be arranged, coastal lagoons are usually forced to rely purely upon the exchange of water resulting from tidal action. Even if two entrances are provided, the path of least resistance between the two entrances is unlikely to be the path through the lagoon given the north to south coastal flow pattern unless unusual circumstances either exist or can be contrived. In this case there was an existing oil protection breakwater that extended offshore for about 4 km from a point between the two lagoon entrances (Figure 2). Providing therefore that this breakwater remained intact, the preferred path for any near shore tidal streams would be through the lagoon rather than around the breakwater. The existing breakwater was therefore exploited to provide a level of flushing in the lagoon that would not have been available on a straight coastline.
The DAWN model was run to simulate a 300 h period following the ‘release’ of a uniform concentration of imaginary tracer dye that was assumed to fill the volume of the lagoon in the initial condition used for the flushing model runs. The worse case scenario based on neap tides was used. Differing lagoon configurations were tested including widening the constriction in the north access channel (Figure 2) and the effect of the inclusion of various screen islands (Al-Handasah, 1994).
The optimal configuration (Figure 3) shows the concentration of the original tracer dye remaining throughout the lagoon at 60 h increments of time up to 300 h. A progressive reduction in concentration of tracer occurs over time so that after 300 h less than 10% of the original is left, except for a small area on the north with 10 to 20% (Figure 3). Thus the objective of a retention period of less then two weeks was achieved and construction of the lagoon followed the optimal design (Figure 3) but with individual islets amalgamated (Figure 2). Based on model predictions the lagoon was constructed in the mid nineties using dredging, excavation, reclamation and filling of selected sites to produce over 1 million m2 of water surrounded by a shoreline of 11 km2 on which housing is currently being constructed (2003).
Physiochemical and biological survey
The original site for the West Bay lagoon was surveyed in 1993 (Halcrow, 1993) and found to be flat land devoid of macroscopic life due to dredged spoil dumping. The area towards the coast was at one time a salt marsh, but construction of a coastal road has prevented inundation leaving a hypersaline pool of approximately 0.25 ha with a depth of 5 cm. The only signs of life were Dunaliella salina blooms and two small stands of Phragmites australis.
In March 2002 surveys of the physical and biological status of the lagoon were initiated at 10 sites within the lagoon and 7 sites on the open coast (Figure 2). These were selected to include comparison of similar sediment characteristics (grain size and organic content) both inside and outside the lagoon. At each station temperature, salinity, pH, dissolved oxygen, nitrite, nitrate and phosphate levels were measured together with chlorophyll-a. Sediment grain size analysis followed the method of Buchanan (1984) and organic content was the difference between dry weight of salt free sediment and the weight of this sediment after ashing in a muffle furnace at 450ˆC for 30 min.
A small grab (0.25 m2) was used to collect triplicate samples of the biota at 1 and 2.5 m depth at each station. These were washed and all biota retained on a 0.5 mm mesh were preserved in 4% formalin for enumeration and identification. In addition, a small Naturalist Dredge (1 m width) was towed for 100 m at 2.5 m depth at all stations to collect epibenthic biota. The survey was conducted 4 times a year over a 2 year period.
In October 2002 seagrass Halophila stipulacea was transplanted into West Bay lagoon to cover an area of 7 × 1.5 m2. This was sampled in triplicate for macrofauna during 2003.
Physical and chemical characteristics
The first data set for stations within and outside the artificial lagoon taken in March 2002 are presented in Table 2. Benthic subtidal sediments within the lagoon with the exception of station 1 are predominately sandy silt while those on the open coast are silty sand, reflecting the sheltered nature of the lagoon. Similarly percentage organic content of sediments within the lagoon are higher (0.2–1.5) than those at stations on the open coast (0.2–0.4).
Seawater temperature, salinity and oxygen levels show no differences between the open sea and lagoon demonstrating a good flushing and circulation within the lagoon. Similarly there is little variation in nitrite, phosphate and chlorophyll levels between the lagoon and the open sea. Nitrate levels ranged from 3.5 to 12.5 μ ml− 1 within the lagoon and 3.8 to 6.8 μ ml− 1 outside, but were very variable between stations with the lowest value at station 9 within the lagoon.
Macrobiota diversity and abundance
Table 3 lists the mean macrobiota diversity and abundance taken subtidally from 1 and 2.5 m at stations 1–17 inside and outside the artificial lagoon. In March 2002 average benthic biodiversity was 15 species per station (range 11–18) within the lagoon in grab samples taken at 1 m depth and 20 species at 2.5 m depth (range 13–27). The dredge sampling produced a mean of 7.3 species per station (range 3–16).
In the open sea grab sampling at 1.0 m yielded a mean of 20 species per station (range 12–21). Although grab samples were not taken at 2.5 m on the open coast, dredge samples gave a mean of 17 species per station with a range of 5 to 35 species per station. All stations on the open coast, except 11, contained live macroalgae and, or sea grass Halodule uninervis and Halophila ovalis. In contrast, seagrass and algae were only found in the entrance (station 1) and exit (station 10) channels of the lagoon.
Table 3 shows that mean abundance of macrofauna at 1.0 m within the lagoon was 1824 m2 (range 260–3432) and at 2.5 m 3648 m2 (range 1340–12400). Dredge samples taken at 2.5 m within the lagoon (100 m tow) gave a mean of 1401 (range 552–3828). Mean abundance taken by grab at 1.0 m outside the lagoon was 6074 m2 (range 1620–20932) and for dredge samples at 2.5 m 1584 (range 88–7625) per 100 m tow. High abundances at individual stations are due to concentrations of Cerithium cingulata and the foraminiferan Spiroloculina.
The Shannon diversity index was 0.65 for 1 m depth and 0.406 for 2.5 m depth between all stations inside and outside the lagoon, and cluster analysis (Jaccard's Coefficient) also reveals high similarity with all stations linked above 0.7. Tables 2 and 3 show little correlation between substrate type and percentage organic content and either diversity or abundance. However, dredge samples containing seagrass or macroalgae (stations 1, 9, 10, 12–17, Table 3) have a mean of 15 species and abundance of 1758 per station, whereas stations 3 to 8 and 11 without seagrass have a mean of only 6 species and abundance of 1101 per station.
Sampling of the transplanted seagrass in the lagoon in January and April 2003 revealed a mean of 17.7 ± 1.3 species (range 16–20, n = 6) within the seagrass bed which was growing well. By comparison, the sandy benthos next to the seagrass contained 14.0 ± 2.1 species (range 12–16, n = 6). Abundances within the seagrass were 10764 ± 2694 m− 2 as opposed to 4905 ± 1517 m− 2 in the bare sandy benthos. Both diversity (p = 0.019) and abundance (p = 0.022) were significantly different.
Present results demonstrate the successful application of hydraulic modeling to produce an adequate flushing regime for artificial lagoons and waterways in the Gulf where tidal ranges are small and high evaporative forces exist. In the final design for West Bay Lagoon water depth was reduced from 3 to 2.5 m and islands enlarged and aligned to create well defined paths of flow around the lagoon (Al-Handasah, 1994). Table 2 shows that in 2002, some 6 years after construction, important water quality indices such as temperature, salinity, oxygen and nutrient levels remain similar to levels observed in the open sea. In addition there is no sign of erosion or further deposition of sediments within the lagoon and intertidal beaches remain stable. In the present case the offshore oil protection breakwater (Figure 1) has forced a significantly higher flushing capability than was predicted.
Long term monitoring of the recovery of oil impacted Gulf shores has shown that soft benthos biota rapidly recolonise within 1 to 3 years once the source of contamination is removed (Jones et al., 1998), so that the high level of similarity observed between open coast and lagoon biota, both in diversity and abundance (Table 3) is not unexpected. Although present data is preliminary and forms part of an ongoing study which will include a study of the meiofauna, it suggests that well designed artificial lagoons and waterways may be as productive as natural open sea coastal habitats.
Of particular interest is the link observed between macroalgae and seagrass and higher macrofaunal biodiversity and abundance (Table 3). This link is well established for the Gulf (McCain, 1984; Coles and McCain, 1990) and it has been estimated that for grassbeds in Tarut Bay, Saudi Arabia 1 km2 of seagrass may support production of 5000 kg of fish and shrimp per annum. While seagrass was present at all stations sampled on the open coast it only occurred in the entrances to the lagoon (Table 3) although similar benthic substrata is present throughout the lagoon. Phillips and Loughland (2002) have demonstrated that while the three species of seagrass occurring in the Gulf rarely flower due to high salinities, and hence natural recolonisation is restricted, they can be transplanted successfully.
In October 2002 seagrass Halophila stipulacea was transplanted to a subtidal benthic site in West Bay Lagoon. Recent (2003) sampling has revealed a further increase in benthic macrofaunal species associated with the creation of this new habitat. It is now planned to release post larval shrimp into the lagoon to see if the waterways will act as a nursery ground for fish and shellfish and to conduct long term environmental monitoring of the physiochemical and biological status of this lagoon.
Most Gulf coastal zone management plans incorporate areas for protection of marine biota although few have legal status or are managed (Krupp, 2002). Links between areas of high coastal productivity, such as mud flats and fisheries are now recognised (Jones et al., 2002b) so that urgent action is required. Gulf fisheries are now fully or over exploited (see above) so that protected areas for fishery management are also required.
The 1991 Gulf War oil release impacted large areas of the coast of Saudi Arabia north of Abu Ali. Recent surveys have shown that most of these coastal ecosystems, particularly salt marshes and tidal flats, remain impacted today. Of even greater concern is the recent review of the Exxon Valdez oil spill in 1989 (Peterson et al., 2003) which reveals that oil related perturbations to food webs still persist with levels of polyaromatic hydrocarbons (PAH) as low as 1 ppb showing effect. Currently many intertidal and subtidal habitats in Kuwait and Saudi Arabia have levels of PAH ranging between 100 to several thousand ppm. In view of the economic value of these damaged habitats (Balmford et al., 2002) unoiled potential nursery areas such as West Bay Lagoon may now be at a premium in the Gulf.
With most countries becoming net importers of fish and shellfish rapid growth in aquaculture is inevitable, but should be regulated to avoid the bad practice seen elsewhere. Culture should concentrate upon local species which show some success (Table 1) such as Sobaity, Sha'm, Hamour and salinity tolerant regional races of shrimp (F. indicus). Introduction of exotic species should be controlled to prevent spread of disease and disruption of Gulf ecosystems caused by escapees. Siting and size of culture operations should be subject to environmental impact assessment to avoid adding further stress to the coastal region, and debate should be encouraged on the potential for stock enhancement as opposed to large scale aquaculture production.
While it is recognised that less biologically significant coastal areas will be zoned for domestic, recreation and touristic development, the present example of West Bay Lagoon Qatar and others such as Al Khaleej Village, Saudi Arabia (Ealey et al., 2001), and most recently Al-Khiran, Kuwait, appear to indicate that such developments do not necessarily result in a major loss of marine productivity. Where a multidisciplinary approach is taken to ensure water quality is maintained, these shallow artificial lagoons and waterways can sustain a high level of productivity and may even extend the current area of coastal biotopes. Further research is required into the manipulation and management of these artificially created habitats through transplantation of seagrass and mangroves, and to explore their potential as nursery grounds for fish and shellfish. Should stock enhancement be possible there may be potential to redress some of the past deterioration of the coastline and fisheries.
Halcrow Water, Swindon, UK for provision of hydrodynamic modeling information and Buro Happold, Bath, UK for data on projects in Kuwait, Saudi Arabia and Bahrain. We are also grateful to Rashid Al-Mehshade, Director of West Bay Lagoon Technical Office for permission to use data and survey the lagoon. Production data and other information of local fish companies or national fisheries departments were provided by Mr. Kevin Copeland, Dr. Abdul Rither Shams, Dr. Mehdi Shakouri, Mr. Jelmar Bechara, and Mr. Hagop Kassabian. Their contributions are gratefully acknowledged.