Distribution of Mangroves along the Red Sea Coast of the Arabian Peninsula: Part 2. The Southern Coast of Western Saudi Arabia M. Asif Khan, Arun Kumar*and Abdul Muqtadir Center for Petroleum and Minerals, Research Institute King Fahd University of Petroleum and Minerals Dhahran 31261, Saudi Arabia *Email:arunkumarlko@hotmail.com Abstract Historical Landsat Enhanced Thematic Mapper (ETM) data of the years 1999, 2000 and 2001 were used to numerically illustrate the distribution of mangroves along the southern Saudi Arabian Red Sea coast from Al-Lith (Latitude 20 o 08' 22'', and Longitude 40 o 16' 17.23'') in the north to the Saudi Arabia - Yemen border (Latitude16 o 41' 16'', and Longitude 42 o 46' 27.18'') in the south. A similar study covering the northern part of the Saudi Arabian Red Sea coast from Sharm Zubair in the north to Al-Lith in the south has already been published as first part of this ongoing study. The distribution of mangroves in both northern and southern Red Sea coast of Saudi Arabia is patchy and they do not occur as a continuous forest and are generally restricted to the low energy quieter environments. Mangroves occupy similar environments in both regions and are under similar stresses caused by various anthropogenic activities and camel grazing. However, mangrove growth in south is relatively denser in comparison to north due mainly to the tropical climate, more wadis, higher rainfall and nutrients and less saline waters. Introduction Saifullah (1994) presents an overview of various mangrove studies along the Red Sea coast of Saudi Arabia and concluded that information on the subject is inadequate. Early publications merely reported on mangrove occurrences (Vessey-Fitzgerald, 1955, 1957; Migahid, 1978) and their brief ecological studies (Zahran et al., 1983; Frey et al. 1984). However, detailed ecological studies of mangrove ecosystem along the Saudi Arabian Red Sea coast were published by Mandura et al. (1987, 1988) Khafaji et al. (1988, 1991) and Saifullah et al. (1989). However, there are no published accounts of geographical distribution, numerical data about area covered and environments of mangrove habitats along the Saudi Arabian Red Sea coast. Present study provides numerical information about area covered by mangroves at several sites and the environments in which they grow along the Red Sea coast of the Arabian Peninsula. Historical Landsat Enhanced Thematic Mapper (ETM) data of the years 1999, 2000 and 2001 was used in this study. First part of this study covered twenty locations covering a length of 930 km of the northern Red Sea coast of Saudi Arabia from Sharm Zubair in the north to Al-Lith in the south (Kumar et al. 2009, Fig. 1&2). We extend that work to the southern Red Sea coast of Saudi Arabia (Fig.1) covering a length of 500 km and it forms second part on this ongoing study. This paper reports similar study on fifteen more sites (Fig.2; sites 21 through 35) and two more locations on offshore islands (sites 36 and 37). Detailed introductory remarks and information about Red Sea is given in Kumar et al. (2010).
Distribution of Mangroves along the Red Sea Coast of the Arabian Peninsula: Part 2: Asif Khan et al. Fig. 1: Study area along the southern Red Sea coast of Saudi Arabia. Fig. 2: Locations of 17 study sites along the southern Red Sea coast of Saudi Arabia Red Sea Coastline of the Arabian Peninsula Red Sea coastline of the Arabian Peninsula is dry without much vegetation except for few species of halophytes and mangroves. Geomorphologically coastal regions vary from rugged coast due mainly to marine terraces to coastal sabkhas, alluvial plains and wadis of up to thirty km width occasionally having small hills of Neogene sediments (Fig. 3). There are a large number of dry river beds, alluvial fans and estuaries locally known as wadis that dot all along this long coastline. The mountains to the east and the coastal 155
plains have large number fluvial channels that transport water and sediment during rains either into the lagoons or in the open sea (Morley, 1975). Due to Quaternary sea-level changes diverse types coastal environments have developed that range from open shelf basins to fringing, barrier or patch reefs to various littoral environments like lagoons (Jado and Zölt, 1984). A large number of coral reef islands of various sizes and shapes are present some near shore and others far offshore in the Red Sea, the most notable being the Farasan Islands which are located around forty km away from the coastline. Several lagoons and bays both small and large meander through this long coastline and at times become saline lakes because they get disconnected from the sea due either to local tectonics or Quaternary sea-level changes. Fig. 3: A generalized geomorphological cross-section of the Red Sea coast of Saudi Arabia showing various environments and plant communities (modified after Saifullah, 1994). Climatically this long coast line covers both tropical and subtropical zones. Monsoons originating in the Indian Ocean cause rain fall in southwestern Saudi Arabia and the area around Al Lith approximately form the northern limit of influence of monsoon in this region. The yearly average rainfall along the foot hills is 100 mm and approximately 300 mm on mountains 1000 m above sea level (Jado and Zölt (1984). Thus rainfall and groundwater enrichment increases significantly from north to south. This demarcation is very interesting and impacts environmental variables and mangrove growth (Table- 1). Surface temperatures in the Red Sea increases southward in response to latitude but salinity of surface water increases northwards indicating intrusion of low salinity water of Gulf of Aden into the Red Sea (Edwards, 1987). The tidal amplitude along the Red Sea coast is very low, which is ~50 cm in the northern and southern coast that gradually decreases towards the center, close to zero near Jeddah (Edwards, 1987). Materials and Methods The study area is located along the southern Red Sea coast of Saudi Arabia from Al-Lith in the north to Saudi Arabia Yemen border in the south between Latitudes 20 o 08' 22'' and 16 o 41' 6'' (Fig. 1 & 2). Historical Landsat Enhanced Thematic Mapper (ETM) data of the years 1999, 2000 and 2001 were used (Table-2). The ETM data has seven spectral bands (Table-3). The spatial resolution of ETM data is 28.5 meters. Research methodology and details about image processing techniques used in this paper is given in Kumar et al. (2010).
Distribution of Mangroves along the Red Sea Coast of the Arabian Peninsula: Part 2: Asif Khan et al. Table-1: Environmental differences between mangroves of northern and southern regions of the Red Sea coast of Saudi Arabia (after Saifullah, 1994). North 1. Sub-tropical and tropical 2. Rocky substrate 3. Fewer Wadis 4. Less rainfall 5. Low nutrients 6. More saline 7. One species of mangroves 8. Poor growth of mangroves 9. Dwarf forest 10. Flowering and fruiting October-April 11. Litter fall 2.16 gm m day 12. Bostrychia tenella absent 13. Mudskippers absent South Tropical only Muddy substrate Many Wadis More rainfall High nutrients Less saline Two species of mangroves Dense growth of mangroves Fringe forest Flowering and fruiting March-August 3gm m day Present Present Table-2: Satellite image data used in the study. Location Sensor Image Acquisition Date site-21 ETM 03-06-2000 site-22 ETM 03-06-2000 site-23 ETM 28-04-2001 site-24 ETM 28-04-2001 site-25 ETM 28-04-2001 site-26 ETM 28-04-2001 site-27 ETM 28-04-2001 site28 ETM 28-04-2001 site-29 ETM 13-08-1999 site-30 ETM 05-04-2001 site-31 ETM 05-04-2001 site-32 ETM 05-04-2001 site-33 ETM 05-04-2001 site-34 ETM 05-04-2001 site-35 ETM 09-09-2000 site-36 ETM 05-04-2001 site-37 ETM 05-04-2001 Table-3: Landsat spectral bands. Landsat 7 (ETM+ sensor) Wavelength (micrometers) Band 1 0.45-0.515 Band 2 0.525-0.605 Band 3 0.63-0.69 Band 4 0.75-0.90 Band 5 1.55-1.75 Band 6 10.40-12.5 Band 7 2.09-2.35 157
Fig. 4: Satellite image of mangroves shown in green color at site 21. Fig. 5: Satellite image of mangroves shown in green color at site 22. Fig. 6: Satellite image of mangroves shown in green color at site 23. Fig. 7: Satellite image of mangroves shown in green color at site 24. Fig. 8: Satellite image of mangroves shown in green color at site 25. Fig. 9: Satellite image of mangroves shown in green color at site 26.
Distribution of Mangroves along the Red Sea Coast of the Arabian Peninsula: Part 2: Asif Khan et al. Fig. 10: Satellite image of mangroves shown in green color at site 27. Fig. 11: Satellite image of mangroves shown in green color at site 28. Fig. 12: Satellite image of mangroves shown in green color at site 29. Fig. 13: Satellite image of mangroves shown in green color at site 30. Fig. 14: Satellite image of mangroves shown in green color at site 31. Fig. 15: Satellite image of mangroves shown in green color at site 32. 159
Fig. 16: Satellite image of mangroves shown in green color at site 33. Fig. 17: Satellite image of mangroves shown in green color at site 34. Fig. 18: Satellite image of mangroves shown in green color at site 35. Fig. 19: Satellite image of mangroves shown in green color at site 36. Fig. 20: Satellite image of mangroves shown in green color at site 37.
Distribution of Mangroves along the Red Sea Coast of the Arabian Peninsula: Part 2: Asif Khan et al. Results and Discussion Fig. 4 through 20 show images of geographical distribution as well as areas of mangroves at sites 21 through 37 respectively (Table-4). Like distribution in the northern coast mangroves along the southern coast also occur in small patches and the areas covered by them vary considerably. They do not occur as a continuous forest and mostly their distribution is restricted to the quieter environments, for example, bays, lagoons, narrow channels, and inland face of offshore islands. However, not all mangroves occupy quieter environments they also inhabit higher energy intertidal environments and seaward face of the near shore islands. The environmental and anthropogenic stress is evident here also as was observed in the northern coast. Saifullah (1994) lists several environmental differences in the mangroves of the northern and the southern Saudi Arabian Red Sea coast (Table-1). We observe denser growth of mangroves along the southern coast in comparison to the northern coast and thus support the observation of Saifullah (1994). This dense growth in south is due mainly to the tropical climate, more wadis, higher rainfall and nutrients and less saline waters along the Red Sea coast. The small size, scattered and sparse distribution of individual trees in the north is due to narrow tidal zone, oligotrophic waters and high salinity of waters along the Red Sea coast (Saifullah, 1994). The mangrove species Avicennia marina occurs all along the Saudi Arabian coast and on the islands, but Rhizophora mucronata occurs only in the Farasan Islands (Mandura et al., 1987). The third and final part of this study will include a similar study along the Red Sea coast of Yemen. Table- 4: Area of mangrove forests (hectares) at the seventeen locations along with their latitude and environmental setting. Site Latitude Deg. Min. Sec. (range) 21 20 08 22 to 19 58 40 22 19 49 22 to 19 33 56 23 19 35 32 to 19 14 25 24 18 53 43 to 18 32 35 25 18 33 16 to 18 21 08 26 18 21 19 to 18 09 44 27 18 12 30 to 18 03 18 28 18 04 06 to 17 54 55 29 17 52 47 to 17 43 02 30 17 37 49 to 17 29 43 31 17 31 34 to 17 23 28 32 17 24 32 to 17 16 26 Mangrove area in hectares Environment 92.8 Bay, intertidal environment 211.3 Lagoons, near shore islands 398.3 Lagoons, near shore islands 103.8 Bay, intertidal environment 130.1 Bays and brackish water coastal lakes 250.8 Lagoons, Bays, near shore islands 207.4 Lagoons, Islands and intertidal environments 284.8 Lagoons, Bays, Islands and intertidal environments 45.1 Bay, intertidal environment 46.0 Lagoon, Bay, intertidal environment 44.6 Lagoons and Bays 129.0 Bays 161
33 17 12 57 to 16 56 59 34 16 53 08 to 16 37 08 35 16 30 47 to 16 21 37 36 16 52 56 to 16 37 51 37 16 49 43 to 16 41 16 519.2 Lagoon, Bay, intertidal environment 186.1 Lagoon, Bay, intertidal environment 90.2 Bay, intertidal environment 181.1 Lagoons, Nearshore islands 35.3 Nearshore islands Acknowledgements: We thank King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia for permission to publish this paper. Reference Frey, W., Kurschener, H., Sheikh, A. M. E. and Migahid, A. M. (1984) Zonation and photosynthetic pathways of halophytes on the Red Sea coast near Tawwal, Saudi Arabia. Notes from the Royal Botanic Garden, Edinburgh, v. 42(1), pp. 45-56. Jado, A. R. and Zölt, J. G. (1984) Quaternary Paeriod in Saudi Arabia. Vol. 2. Springer-Verlag, 360p. Khafaji, A. K., Manfura, A. S. and Saifullah, S. M. (1988) Temporal and spatial variations in the carbohydrate, lipid and protein contents of Avicennia marina from the Saudi Arabian Red Sea coast. Proceedings Saudi Biological Society, v. 11, pp. 149-161. Khafaji, A. K., Manfura, A. S., Saifullah, S. M. and Sambas, A. Z. (1991) Litter production in two mangrove stands in southern Red Sea coast of Saudi Arabia (Jizan). Journal of King Abdulaziz University, Marine Science, v. 2, pp. 93-100. Kumar, A., Khan, M. A. and Muqtadir, A. (2010) Distribution of mangroves along the Red Sea coast of the Arabian Peninsula: Part-l: the northern coast of western Saudi Arabia. e-journal Earth Science India, v. 3 (1), pp. 28-42. Mandura, A. S., Khafaji, A. K. and Saifullah, S. M. (1987) Mangrove ecosystem of southern Red Sea coast of Saudi Arabia. Proceedings Saudi Biological Society, v. 10, pp 165-193. Mandura, A. S., Saifullah, S. M. and Khafaji, A. K. (1988) Ecology of a mangrove stand of central Red Sea coast area: Ras Hatiba (Saudi Arabia). Proceedings Saudi Biological Society, v. 11, pp.85-112. Migahid, A. M. (1978) Flora of Saudi Arabia, Two Volumes, 2 nd Edition. Riyadh University Publications, Riyadh, 650 p. Morley, N. F. J. (1975) The coastal waters of the Red Sea. Bulletin Marine Research Centre, Saudi Arabia, v. 5, pp. 8-19. Saifullah, S. M., Khafaji, A. K. and Mandura, A. S. (1989) Litter production in mangrove stand of the Saudi Arabian Red Sea coast. Aquatic Botany, v. 36, pp. 79-86. Saifullah, S. M. (1999) Mangrove ecosystem of Saudi Arabian Red Sea coast an overview. Journal of King Abdulaziz University, Marine Science, v. 7, Special Issue on Red Sea Marine Environment, Jeddah, 1994. pp. 263-270. Vesey-Fitzgerald, D. F. (1955) Vegetation of the Red Sea coast south of Jedda. Saudi Arabia. Journal of Ecology, v. 43, pp. 477-498. Vesey-Fitzgerald, D. F. (1957) Vegetation of the Red Sea coast north of Jedda. Saudi Arabia. Journal of Ecology, v. 45, pp. 547-562. Zahran, M. A., Younes, H. A. and Hajrah, H. H. (1983) On the ecology of mangal vegetation of the Saudi Arabian Red Sea coast. Journal of University of Kuwait, Science, v. 10 (1), pp. 87-99.