New Mangrove Ecosystem Data Along the UAE Coast Using Remote Sensing A

New mangrove ecosystem data along the UAE coast using remote sensing A. Al Habshi,1 T. Youssef, 2,∗ M. Aizpuru, and F. Blasco3 1Abu Dhabi Company for Onshore Oil Operations (ADCO), PO Box 270, Abu Dhabi, UAE 2Biological Department, UAE University, PO Box 17551, Al Ain, UAE 3Laboratoire d’Ecologie Terrestre, CNRS/Universit´eToulouse III, France ∗Corresponding author: [email protected]

Characteristics of mangrove communities along the Gulf Coast of the UAE were explored using high- resolution satellite data Terra ASTER imageries in the common visible and near infra-red bands. Mangrove stands in three geographically distinctive sites, Khor Kalba, Khor Umm Al-Quwain and Al Dabbiya, were studied through spatial data and ground veriﬁcation surveys. Mangroves in the UAE appear in patchy and scattered patterns, occupying about 40 km2 of the coastal zone, half of which are located in Abu Dhabi in sheltered lagoons. The remaining areas are linear communities fringing tidal waterways distributed along intertidal zones. Their distribution is limited however, by aridity and site topography. Despite similarities in substrate conditions, differences in climatic and vegetation characteristics between the three sites indicate that growth conditions seem to be more favourable at Khor Kalba with the higher winter temperatures and higher annual rainfalls. Nine main units were recognized on the colour composite image of the Terra ASTER space data; dense vegetation, scattered vegetation, algal deposits, dry sand, sabkhas, settlements, recent deposits and turbid water, shallow water and deep water. Radiance did not allow for the separation of mangrove areas from inland vegetation through the supervised classiﬁcation. Confusion was also encountered between different soil classes (e.g. wet soils) and settlements or roads. It is concluded, therefore, that satellite data such as SPOT and Terra ASTER can be effectively analyzed through visual interpretations supported by local digital enhancement.

Keywords: mangrove, ground veriﬁcation, Arabian Gulf

Introduction Theophrastus over 2,000 years ago (Spalding et al., 1997). Mangroves comprise a biologically signiﬁcant The Arabian Gulf represents one of the northern and productive component of the land-sea interface limits to mangrove distribution in the region. It is of tropical and subtropical regions of the world. Only one of the most arid of all mangrove ecosystems, 125–130 km2 of mangroves are recognized in the with the least vegetation biodiversity in the world. Gulf, 80% of which are on the Iranian side. Despite Only one species, Avicenna marina, has managed their limited size, mangroves in the Gulf were the to survive and dominate the mangrove ecosystem ﬁrst to be recorded in the literature by Nearchus and along the Gulf coast of Bahrain, in Qatar with a

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Aquatic Ecosystem Health & Management, 10(3):309–319, 2007. Copyright C 2007 AEHMS. ISSN: 1463-4988 print / 1539-4077 online DOI: 10.1080/14634980701512525

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decrease in population towards the north western (February–March 2002) and summer (July–August part of the inner Gulf. Mangrove trees are not found 2002 and in February 2005). Inter-annual variation in Kuwait and most of the north eastern coasts of of climatic factors between 2001 and 2003, includ- Saudi Arabia (ROPME, 1999). However, there is ing annual rainfall and temperature variations were evidence that Rhiozphora mucronata has previously also recorded for the three localities. occurred in the Gulf (Böer and Lieth, 1999). The structure of mangrove stands was mea- Mangrove ecosystems inaccessibility is the main sured as described by Cintron and Schaeffer-Novelli obstacle for traditional ecological surveys (Spalding (1984). Five transects were randomly selected and in et al., 1997). Subsequently, the number of studies re- each transect six sampling points were carefully lo- lated to mangrove ecology using satellite data is now cated and four quarters were established by crossing increasing. As the approaches involved are not fully the compass direction of the transect line with the developed, only a few of these studies were related to perpendicular line. Subsequently, a total of twenty- arid mangrove ecosystems. The quality of the satel- four points were sampled on each transect. The dis- lite products is generally dependant on the climatic tance between trees, the diameter of each tree at conditions and the nature of the vegetation to be breast height (dbh), its height and mean basal area examined (Blasco et al., 2001). Even with the aid were recorded. of satellite data, vegetation analysis remains com- At each point in the various transects, a surface plex, time consuming and in most cases ground ver- soil sample (0–15 cm) was collected and analyzed ification is necessary to discriminate against other for the determination of soil moisture. Air-dried coastal vegetation (ERWDA/JODCO/ARSA, 2003). soil samples were analyzed using Micro-Kjeldahl This study explores the characteristics of man- for plant available Nitrogen. Potassium, Phosphorus grove communities in the hyper arid environment of and Calcium were estimated using atomic absorp- the Gulf Coast of UAE using high-resolution satel- tion (Aventa, USA). Salinity was measured using a lite Terra ASTER imageries in the common vis- hand held refractometer, (ATAGO, Japan). ible and near infra-red bands. The specific aim of this work is to distinguish between structural char- Remote sensing studies acteristics of mangrove stands in three geographi- Due to their vast discontinuous distribution cally distinctive sites along the hyper arid coast of around the world, often in the form of narrow belts, UAE; Khor Kalba, Khor Umm Al-Quwain and Al it is almost impossible to monitor mangrove ecosys- Dabbiya. tems without having easy access to satellite technology (Spalding et al., 1997). Even with these facil- Materials and methods ities, the task remains extremely complex and time consuming. Study sites The type of satellite products that are at our disposal primarily determines the applications of satel- Three tide-dominated vegetation type-sites were lite technology to coastal vegetation studies. They selected for this study; Khor Umm Al-Quwain (Lat. also depend on the climatic conditions and on the 25◦32N, Long. 55◦35E), including 8.5 km2 of man- correlated nature of the vegetation. groves; Al Dabbiya (Lat. 24◦15N, Long. 54◦10E) Although the number of references related to with about 3.6 km2 of mangroves; and Khor Kalba mangrove studies using satellite data are progres- (Lat. 25◦05N, Long. 56◦25E). These test sites se- sively increasing since the launch of the first high lected from the west to the east coastline offer the resolution instrument (SPOT 1 in 1986), our general advantage of illustrating a gradient of “Continental- bibliography showed that only about 10, at the most, ity” from the inner to the outer Gulf (Figure 1). are devoted to mangroves of arid coasts. This means Ecological surveys were performed over these that these approaches are still at a research level. This three different localities to identify aridity gradi- study focused on the coastlines of the United Arab ents that could explain the biological and environ- Emirates, on the three test sites described above. mental differences between the concerned sites and The purpose of this experiment is to test the possible distinct vulnerabilities of mangrove species ability of high-resolution satellite data (in the com- and habitats. Three ecological field surveys of man- mon visible and near infra-red bands) for map- grove vegetation, water and sediments were carried ping mangrove communities in arid environments. out over the localities described above in winter This study also aims at understanding the structural

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Figure 1. The three study areas along the UAE coast.

characteristics of mangrove stands in Khor Kalba, AST L1B:003 2008703534, 30 September 2002 on Khor Umm Al-Quwain and Al Dabbiya in the UAE. Umm Al Quwain We discuss to what extent the differences found AST L1B:003. 2008765442, 5 July 2002 on Kalba. in these three test sites determine habitat speciﬁc conditions and the input of satellite data for the These images were processed following the method study and monitoring of these arid coastal ecosys- illustrated by ENVI and IDRISI software. Out of the tems. Based on the recent development regarding 14 ASTER channels (2 visible, 1 near infra-red, 6 the use of remote sensing for coastal vegetation middle infra-red, 5 thermal infra-red), only 3 chan- studies in the United Arab Emirates, using Terra nels were registered through ENVI software: ASTER sensors (ERWDA/JODCO/ARSA, 2003), we used high-resolution satellite coverage, or Terra Band 1 (0.52–0.60 μm), green ASTER imageries. Three recent ASTER scenes Band 2 (0.63–0.69 μm), red (15m ground resolution in visible and near infra- Band 3N (0.78–0.86 μm), near infrared. red bands) were acquired through Eros Data Center (US Geological Survey) facilities: These 3 visible and near infra-red bands only have a ground resolution of 15m, instead of 30 m for middle or short-wave (SWIR) infra-red and AST L1B:003:2007218008, 10 June 2002 on Al 90 m for thermal infra-red. The processing level Dabbiya was 1B, meaning data has been radiometrically and

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geometrically corrected and is re-projected on UTM is higher (around 40 km2). Mangroves in the UAE map projection. Each ASTER scene covers 60 km are distributed in about 20 major sites (Khan, 1982; by 60 km; the bounding coordinates are given in the Western, 1989; Embabi, 1993; Böer and Gilddon, header file. 1998, 1999; Dodd et al., 1999). Their distribution is Through visual interpretation, the main type of not only limited by aridity. Coastal topography plays useful information that can be extracted from space a major role in the patchy and scattered pattern of is the delineation of main physiognomic units, their mangroves along the coastal strip of the UAE. In spatial distribution and aerial extent, their ecological general, the three main constraints controlling the status, their phenology and evolutionary trend. distribution of mangroves in the Gulf are the high Special emphasis was put on wet coastal ecosys- salinity of seawater (average around 40 ppt in open tems, which constitute patchy fringes of natural or waters and 45 ppt in lagoons), wide seasonal vari- restored vegetation in the inter-tidal zone (red and ation in air temperatures and poor soil conditions. pink on the colour composites). With the exception Variation between roughly estimated mangrove area of mangroves, salt marshes and some algal deposits of the gulf countries compared with that of UAE is (black on the colour composites), the vegetation of given by Saenger et al.,2002 (Table 1). Compared the mainland is extremely sparse and almost im- sites were described based on salinity, temperature possible to discriminate from space. Several other and soil conditions. important data have not been successfully extracted Mangroves normally establish on sheltered or from satellite data, such as the standing biomass, protected areas from strong winds and waves along the height of trees, the age of the stands, soil prop- the coast. These observations were supported by erties, etc. The ground verification visits and field Kogo et al. (1986) who demonstrated on exposed surveys described above were carried out to obtain shores of Mubarraz Island of Abu Dhabi that 60 the missing information. to 80% of newly planted propagules were washed away compared with only 10% on more sheltered Results and discussion shorelines. Hornby et al., 1997 stated that the mangroves of the UAE are often concentrated in lagoons UAE mangroves as part of the Gulf (Khors) in which they occupy at least 2,500 ha. How- ever, these authors emphasize that there are other In the UAE, the total extent of mangroves is not extensive areas of mangroves in the UAE that are confirmed and still requires validation. Figures cur- not regarded as part of the mainland intertidal zone rently available are extremely variable. According and were, therefore, not estimated by their survey. to Rabanal and Beuschel (1978), there were around Approximately half of the mangroves in the UAE 3000 hectares (30 km2) of mangroves in the UAE, were found in Abu Dhabi in sheltered lagoons. The but our estimate supported by satellite data analysis remaining areas are linear communities of fringing

Table 1. Synthesis of mangrove ecosystems areas in arid and hyper-arid environments in a number of Arabian Gulf Stations (from Saenger et al., 2002).

Approx. Main Example Number Mean Mean Signiﬁcant Area Approx. Climatic of of water canopy fresh water Country Km2 Latitude Type (1) Locality species salinity height supply Bahrain 4 26◦N Hyper-arid Tobly Bay 1: A. marina 38 4 m No Iran 89 25–28◦N Arid Khorasan Straits 1: A. marina ?? ? Oman 11∗ 16–26◦N Arid Nuqdah 1: A. marina 35–40 3–5 m Yes Qatar 9 25◦30’N Arid Dhakhira Bay 1: A. marina 35–40 3–5 m Yes Saudi 204 24–27◦ Arabic Gulf Al Khafji 28◦30 1: A. marina 35–40 3 m No Arabia 30N (hyperarid) Northern limit 12◦40- Oman sea and Yanbu Al- 1 or 2 Avicennia 35–40 No 29◦N Red sea (arid) Sinaiyah 24◦07N R. mucronata UAE 40 24–20◦N Arid Al Dabbiya 1 A. marina 35–42 3–5 m No

∗This number was added from another source (see Cookson et al., 2001).

tidal waterways distributed along intertidal zones of Table 3. Structural components of various mangrove stands at some lagoons and islands from Khor Kalba on the the study areas. east coast, Ras Al Khaimah in the north, to Abu Average Average Average mean Average Dhabi and other islands in the west. Dbh Height Density Soil The direct human use of mangroves in the Gulf Site (cm) (m) (ha−1) Salinity is very limited; they are used in some areas as fod- der for camels, for fuel, and in providing stakes for Al Dabbiya 1.38 1.97 2450 50.6 fishing, which largely explains why all mangroves in Khor Kalba 4.58 3.08 0980 57.9 the Gulf region are subject to severe socio-economic Umm AL 7.41 3.35 1080 43.8 Quwain stressors resulting from the vast development of the regions countries. These stressors are: conversion to urban development, conversion of harbours and Mangroves characteristics channels and disposal areas for solid waste/garbage. Umm Al Quwain was the most vigorous in the three sites under study (Table 3) with trees reaching Aridity of UAE climate a mean height of 3.35 m. The average height is similar in Khor Kalba and in Al Dabbiya (1.97 m). Simi- The climate of the UAE was described by Böer larly, diameter at breast height (dbh) decreased from (1997). Variation of climatic factors between 2001 7.41 cm in Umm Al Quwain to 1.38 cm in Al Dab- and 2003 showed that the daily temperature ranged biya. It can be generally concluded that, growth con- between 47.7◦C and less than 8.0◦C in all studied lo- ◦ ditions seem to be more favourable at Khor Kalba cations, but no temperature below 5 C was recorded with the higher winter temperatures and higher an- during that period (Table 2). Taking into account that nual rainfalls. In addition, historical data seems to the Gulf is theoretically located in a warm coastal confirm that Khor Kalba mangroves are the oldest zone, the winter figures can be considered relatively and they are genetically different from those of the low. In addition, the annual rainfall is generally very inner Gulf (Dodd et al., 1999). low (90 to 120 mm); it is lower in Al Dabbiya (Abu UAE Soil is generally sandy. No mangrove Dhabi) than in Khor Kalba and Umm Al-Quwain. ecosystems were observed in the UAE on coral rocks The average rainfall in Khor Kalba is higher than in or on pure sandy beaches. In the studied localities, the other two sites (Table 2). Data recorded in the almost 95% of soil texture consists of fine sand last 20 years at this station show that the monsoon (Table 4), whereas silt and clay fractions represent regime of the Arabian Sea influences the climate of less than 10% of the solid particles. the Oman coast at Khor Kalba. The physical conditions of the substrate in the The average local seawater temperature ranges ◦ ◦ three study sites indicate very little variation, with a from 18 Cto34 C indicating that UAE has probably slight increase of sand content in Khor Kalba than in a much greater annual temperature than expected. the other two sites. Values of exchangeable cations The mean annual relative air humidity is 60%. On i.e. N, P, K, and Ca, shown in Table 4, indicate that average, Al Dabbiya (Abu Dhabi) seems to be rela- nitrogen levels were higher in Al Dabbiya (ranging tively more humid than Kalba and Umm Al Quwain. from 579.3 to 6122.4 ppm). In contrast, phosphorus levels were generally high in all three sites, (Al Table 2. Mean climatic data of the study areas. Dabbiya, 4.5 to 153.4 ppm; Kalba, 9.4 to 29.8 ppm; Umm Al Quwain, 7.1 to 64.4 ppm). No differences Mean annual Temperature◦C were measured between the three sites in Potassium rainfall (mm) contents. The highest Calcium levels were found Site 1976–2001 Abs. Max Abs. Min at Umm Al Quwain (470 to 542 ppm), while in Al Dabbiya 91.2 47.7 8.8 Kalba they varied from 34.8 to 130, and from 130 Khor Kalba 144.3 46.5 14.3 to 545 ppm in Al Dabbiya. Values for calcium and Umm Al 109.8 46.5 8.0 potassium reflect the overall influence of regular re- Quwain plenishment by seepage and tides. Water content in the soil was almost the same in the three sites. Source: National Meteorological Data Bank, Meteorological De- Salinity is known to play a significant role in department, Ministry of Communication, UAE. termining the structural characteristics of mangrove

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Table 4. Chemical Properties of soils at test sites (2002).

Site

Al Dabbiya Umm Al Quwain Khor Kalba

Main soil components Min Max. Mean Min Max. Mean Min Max. Mean Granulometry % Sand 94.893.595.2 % Clay/silt 5.26.54.8 Nitrogen (ppm) 579.3 6211.4 1449.8 215.6 1617.7 703.1 240.3 2811.2 1072.8 Potassium (ppm) 23.245.732.118.049.531.022.971.647.3 Phosphorus (ppm) 4.5 153.420.37.164.419.69.429.817.1 Calcium (ppm) 130.0 545.0 501.0 470.0 542.0 527.134.8 130.078.6 Water content (%w/w) 0.10.60.30.20.40.30.10.40.3 Pore water salinity (ppt) 40.070.050.935.065.043.940.063.051.5

vegetation (Cintron et al., 1978). The high pore wa- tations in settlements remained to be classified as ter salinity levels confirm the extreme conditions in mangrove. Confusion was also encountered between which these mangroves develop. Table 4 shows pore different soil classes (e.g. wet soils) and settlements water salinity measurements during winter period of or roads (Figs. 3 and 4). However, as the present 2002; they ranged from 40% to 63% (ppt) in Kalba, work focuses on the tidal zone of the typical coastal 35 to 65 ppt in Umm Al Quwain and 40 to 70 ppt in units, this confusion should not have any impact on Al Dabbiya. This interstitial salinity changes in the the principal objective of the study. summer when it seems to increase by about 10% to An overview of the most important ground units 20%. identified during field trips was obtained; most radiometric classes correspond to almost bare soils Remote sensing data with distinct colours, natures (sandy, loamy, clayey, etc.) and humidity. Continental soils are dry and Taking into account the importance of soil re- bright whereas coastal soils are more or less wet flectance in each open vegetation class, in the spec- and darker. In some parts, Cyanophyceae deposits tral response it can be assumed that some thematic form caps on mudflats at low tide. Almost all these units (like mangroves) could be subdivided into sev- coastal ecosystems appear distinctly. As several sub- eral radiometric classes. According to soil properties strate conditions strongly influence the signal in the at the time of satellite pass, i.e. wet or dry, organic intertidal zone definition, care was taken in select- matter content, soil originated from coral reefs or ing several classes of open stands. Sample sizes are from sandy beaches, etc. In other words, the dis- not constant; special attention has been paid to their crimination of mangrove types is primarily induced extent depending on the parameters, homogeneity by the vegetation cover density and by the colour of and extension. the soil. In very dry coastlands, the interpretation of satel- The main units that can be recognized on the lite products is simplified by the fact that Avicennia colour composite image of these space data are: trees and shrubs are evergreen with broad leaves, dense vegetation (red), scattered vegetation (pink), contrasting with other coastal desert habitats which algal deposits (black), dry sand (white), sabkhas, are poorly vegetated or barren at any moment of humid soils, settlements (grey), recent deposits and the year. Paradoxically, even in the UAE, the risk of turbid water (light pink), shallow water (blue) and confusion between dense mangroves and algal mats deep water (black) (Figs. 2, 3, 4). deposited in the intertidal zone is possible. Young During the supervised classification, radiance did planted mangroves or open mangroves with ground not allow the separation of mangrove areas from coverage lower than 40% to 50% are difficult to inland vegetation. Under this very arid environ- discriminate from the space, because the complex ment, however, mangroves are the only spontaneous response of the substrate tends to mask the vege- coastal vegetation. Still, some tiny patches of plan- tation signals almost in every spectral band. Under

Figure 2. Al Dabbiya area from ASTER.

conditions similar to the UAE environment, remote imposition of visible data sets with microwave data sensing technology does not allow work in real time. for the delineation and aerial quantification of a lim- As soon as the average climatic conditions become ited number mangrove sub-classes according to their humid or sub-humid the acquisition of satellite prod- density structure and possibly also to their floristic ucts becomes more difficult. components. The problem of integration of multiple data sets Taking into account the importance of soil re- and how to analyse them remains crucial, especially flectance in each open vegetation class, in the spec- in wet coasts. Perhaps the most rigorous practical tral response, it can be concluded that the discrim- processing method would be the result of a super- ination of mangrove types is primarily induced by

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Figure 3. Khor Kalba area from ASTER. the vegetation cover density and by the colour of the ited to some important geographical data, such as soil (Blasco et al., 2002). the exact delineation of mangrove stands and their Figure 5 shows that the dense Avicennia man- aerial extent. In the UAE and elsewhere, the quality grove curve is quite characteristic of any dense of the image processing improves when the amount green forest cover, whereas open Avicennia man- of ﬁeld data and ground veriﬁcation increases. Most groves appear differently on soils of different mois- ecological data related to soil properties (mechani- ture and different organic matter contents. The last cal and chemical properties), bioclimatic peculiari- three spectral responses corresponding to a single ties (aridity index, air humidity, winds speed, etc.), class (Open Avicennia mangrove) can be grouped. biodiversity and age of forest stands or plantations, For this approach, it can be concluded that the stems densities, etc, have to be considered as an- input to our knowledge of satellite imageries is lim- cillary data to be gathered from ground surveying.

Figure 4. Umm Al Quwain area from ASTER.

None of them can be satisfactorily measured directly products. Several classes of mangrove forests can from space data. be satisfactorily discriminated in arid coastal areas. A comparison of our data from Terra ASTER This is presumably partly due to the fact that Avi- products and SPOT4 HRVIR for coastal studies in cennia trees and shrubs are evergreen, with broad hyper-arid areas as in the Arabian Gulf shows that leaves, contrasting with other coastal desert habitats at 15m, which is the finest resolution provided by that are poorly vegetated or barren. ASTER VNIR, it is likely to lead to a reliable iden- In spite of unavoidable difficulties to properly tification and delineation of most mangroves in this identify scattered microphyllous bushes in arid part of the world. This is an important result because countries (ground coverage lower than 30%), it is for the first time a rigorous assessment of these very realistic to conclude that the inventory and monitor- valuable ecosystems can be carried out with space ing of dense mangroves which are being replanted

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Figure 5. Spectral characteristics of mangrove forests (SPOT 4-HRVIR data).

and restored over large stretches along the United Böer B., Gilddon, D., 1998, Mapping of coastal ecosystems and Arab Emirates coast is readily possible with data halophytes—case study of Abu Dhabi ,United Arab Emirates, provided by optical sensors (VNIR + SWIR). Mar. Freshwater Res., 49, 297–301. Böer, B., 1997. An introduction to the climate of the United Arab Emirates. Review. Journal of Arid Environments 35, 3–16. Böer, B. Lieth, H., 1999: Halophytes for seawater irrigation in the Conclusions and Arabian peninsula—a review. In: H. Lieth, A. Hamdy, H.-W. recommendations for Koyro & M. Moschenko (Eds.), Halophyte crop development for different climates. Ecological and Eco-physioloical con- future studies tributions. Proceedings of the 3rd seminar of the EU Con- certed Action group IC 18 CT 96-0055. University Paderborn, For future studies, it is recommended to consider Paderborn. the following: Cintron, G., Schaeffer–Novelli, Y., 1984. Methods for studying Considering the amount of work carried out on mangrove structure. In: S. C. Snedaker and J.G. Snedaker, mangrove ecosystems in the Gulf since the 1970s, it (Eds.), The mangrove ecosystems: Reseach methods, pp. 91– would be highly useful to establish a “Gulf mangrove 113. UNESCO, Paris. Cintron G., Lugo, A., Pool, D. J., Morris, G., 1978. Mangrove working group.” of arid environments in Puerto Rico and adjacent islands. It would also be useful to publish a review on what Biotropica 10(2), 110–121. recommendations have been developed for man- Cookson P., Shoji, T., Jupp, B. P., 2001. A review of 10 years of grove research and development in the Gulf. Scientific Studies on Mangroves in Oman (1990-2001), Pro- ceedings of the 2nd International Symposium and Workshop on Arid Zone Environments 2001 Dec. 22–24, Abu Dhabi, ERWDA, UAE. References Dodd, R., Blasco, F., Rafii, Z., Torquebiau, E., 1999, Mangrove Al-Eisawi D. M., 2000. Status and Threats to Mangrove and Salt (Avicennia marina) and their diversity in cuticular hydrocar- Marsh Ecosystems in Bahrain Proceeding of the 2nd Interna- bons composition in the arid zones of the United Arab Emi- tional Symposium and Workshopon Arid Zone Environments rates. Aquatic Botany 63, 291–304. 2001 Dec. 22–24, Abu Dhabi. ERWDA, UAE. Embabi N.S., 1993. Environmental aspects of geographical distri- Blasco, F., Zipuru, M., 2002, Mangrove along the costal stretch bution of mangrove in the United Arab Emirates. In: H. Lieth of Bay of Bangal: Present status. Indian Journal of Marine and A. Al Masoom (Eds.), Towards the rational use of high Sciences 31(1), 9–20. salinity tolerant plants, Vol.1, pp. 45–58. Kluwer Academic Blasco, F., Aizpuru, M., Besnehard, G., 2001. Mangrove coasts. Publishers, Dordrecht. In: M. Schwartz (Eds.), Coastal Encyclopaedia, pp. 245–256, ERWDA/JODCO/ARSA 2003, Workshop on Remote Sensing. Kluwer Academic Publishers, Dordrecht. 2003 October 11–15. Abu-Dhabi, UAE.

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