distribution of mangroves along the red sea coast of the arabian...

Open access e-Journal Earth Science India, Vol. 3 (III), July, 2010, pp. 154-162 http://www.earthscienceindia.info/; eISSN: 0974 – 8350

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:[email protected]

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

20o 08' 22'', and Longitude 40o 16' 17.23'') in the north to the Saudi Arabia -Yemen border (Latitude16o 41' 16'', and Longitude 42o 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.

155

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


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 20o

08' 22'' and 16o 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).


157

Table-1: Environmental differences between mangroves of northern and southern

regions of the Red Sea coast of Saudi Arabia (after Saifullah, 1994).

North South

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

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


Fig. 4: Satellite image of mangroves

shown in green color at site 21.












159






















Fig. 20: Satellite image of mangroves shown

in green color at site 37.


161

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)

Mangrove area in

hectares

Environment

21 20 08 22 to

19 58 40

92.8 Bay, intertidal environment

22 19 49 22 to 19 33 56

211.3 Lagoons, near shore islands

23 19 35 32 to

19 14 25

398.3 Lagoons, near shore

islands

24 18 53 43 to

18 32 35


25 18 33 16 to

18 21 08

130.1 Bays and brackish water

coastal lakes

26 18 21 19 to

18 09 44

250.8 Lagoons, Bays, near shore

islands

27 18 12 30 to

18 03 18

207.4 Lagoons, Islands and

intertidal environments

28 18 04 06 to

17 54 55

284.8 Lagoons, Bays, Islands and

intertidal environments

29 17 52 47 to

17 43 02


30 17 37 49 to

17 29 43

46.0 Lagoon, Bay, intertidal

environment

31 17 31 34 to

17 23 28

44.6 Lagoons and Bays

32 17 24 32 to 17 16 26

129.0 Bays


33 17 12 57 to

16 56 59


environment

34 16 53 08 to

16 37 08


environment

35 16 30 47 to

16 21 37


36 16 52 56 to

16 37 51

181.1 Lagoons, Nearshore islands

37 16 49 43 to

16 41 16

35.3 Nearshore islands

Acknowledgements: We thank King Fahd University of Petroleum and Minerals (KFUPM),

Dhahran, Saudi Arabia for permission to publish this paper.

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