Status and Ecology of Sirenian, Cetaceans and Marine Turtles in the Farasan Bank, Red Sea, Saudi Arabia
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JKAU: Mar. Sci., Vol. 26. 1, pp: 1-8 (2016 A.D. / 1437 A.H.) DOI :10.4197/Mar. 26-1.1 Status and ecology of Sirenian, Cetaceans and marine turtles in the Farasan Bank, Red Sea, Saudi Arabia Ahmed M. A. Al-Mansi Saudi Wildlife Authority Email: [email protected] Abstract. This paper presents preliminary data regarding the status, general distribution and habitat use of cetaceans, sirenian and marine turtle species inhabiting the Farasan Bank in the south-east of the Red Sea. The survey was conducted in April 2009 as part of a joint project by the Khaled Bin Sultan Living Ocean Foundation and the Saudi Wildlife Authority. With respect to habitat use of these species, the Common Dolphins, Delphinus delphius, were recognized in the offshore waters around the islands and the reefs; whereas the Bottlenose Dolphins, Tursiops truncatus, showed a preference for deeper waters. The Hump- backed Dolphins, Sousa chinensis, were sighted near an island with mangrove swamps and the Spinner Dolphins, Stenella longirostris, inhabited sheltered shallow water. The Bryde's whales, Balaenoptera edeni, were found in offshore waters which are of high productively. The Dugongs, Dugong dugon, used shallow water habitats characterized by seagrass meadows. The habitat use of the marine turtles found in the study area was also distinct. The Hawksbill turtles, Eretmochelys imbricata, were recorded within the coral reefs, whereas the Green Turtle, Chelonia mydas, were seen near the seagrass beds. The results of this study provide an important baseline data on the ranges and abundance of some endangered animals. These data along with a greater understanding of species distribution and habitat use will prove to be important for the proposing the Farasan Bank as Marine Protected Areas in this part of the Red Sea. Introduction land and the islands, patch reefs, small atolls The study area extends from Al Lith to and barrier reefs), seagrass beds, algal reefs, Am'mag, 70 Km south of Alqunfudah and mangrove stands, and intertidal flats. Two covers an area of about 220 km north to south orders of marine mammals occur in the Red and 45 km east to west, with a total area of Sea, comprise order Sirenia which is (km²; consists of many islands، all of represented by the Dugong (Dugong dugon 11915 which are uninhabited. The area has a complex family Dugonidae, and orde Cetacea which tectonic history of uplift and subsidence, has several species of dolphins (family related to the rift development of the Red Sea Delphindae) and few species of whales (family as a result of the movements of the Arabian Balaenopteridae) (Frazier et al., 1987; and African tectonic plates (Braithwaite, Basuony, et al., 2010). The cetaceans known 1987). The area has a wide range of habitats, to inhabit the Red Sea include 11 species from including coral reefs (fringing reef of the main the family Delphinidae: the Common Dolphin 1 2 Ahmed Al-Mansi Delphinus delphinus delphis cf. tropicalis Marine turtles in the Red Sea nest on a (Baldwin, 2003); Short-finned Pilot Whale number of islands and at a few mainland Globicephala macrorhynchus (Leatherwood locations along the length of the Red Sea et. al., 1991): Risso’s Dolphin Grampus including Saudi Arabian coasts (Frazier, et al., griseus (Robineau & Rose 1984, Frazier et. 1987). Miller (1989) found in his survey that al., 1987); Killer Whale Orcinus orca (Frazier marine turtles nest in the vicinity of Tiran et. al., 1987); False Killer Whale Pseudorca Island in the north, Al-Wajh Bank, along the crassidens (Frazier et. al., 1987); Indo-Pacific coast near Yanbu, on the offshore islands hump-backed dolphin or Plumbeous Dolphin south of Al-Qunfudhah and on the islands of Sousa chinensis (Robineau & Rose 1984, De the Farasan Bank. According to Frazier et al., Silva 1987, Frazier, et al., 1987); Rough- (1987) five of the seven recognized marine Toothed Dolphin Steno bredanensis turtle species have been recorded in the Red (Leatherwood et. al., 1991); Bottlenosed sea waters viz. the Green turtle (Chelonia Dolphin Tursiops truncates (Robineau & Rose mydas), Hawksbill turtle (Eretmochelys 1984, Frazier et. al., 1987, Leatherwood & imbricata), the Loggerhead turtle (Caretta Reeves 1990); and two species from the family caretta), Olive Ridley turtle (Lepidochelys Balaenopteridae viz. the Minke Whale olivacea), and Leatherback turtle Balaenoptera acutorostrata (Leatherwood & (Dermochelys coriacea). Due to their nesting Reeves 1983) and the Bryde’s whale B. edeni areas and abundance within the Kingdom's (Mahdi 1967, Sheppard et. al., 1992). Most waters, the Green and Hawksbill turtles are reports are based on incidental sightings or considered most important to the turtle specimens, and there is very little published conservation efforts in the Kingdom. information on the ecology, behaviour, or However, the distribution of marine turtles conservation status of the Red Sea cetaceans. away from nesting beaches in the Red Sea is In the Red Sea, dugongs occur along the poorly known and the environmental variables entire eastern coast between Aqaba in the which influence turtle’s distribution at the sea north and Bab al Mandab in the south; have not been investigated in any detail. however their distribution is very patchy, Therefore, such information will be extremely reflecting the availability of suitable habitat. important for the evaluation of habitat The key habitat patches for the Dugongs occur utilization. Data collected on marine turtles along the Al-Wajh Bank, the Al Lith area, and and mammal diversity as well as the the Gazan-Luhaiyah area (Yemen) (Preen, representativeness and conservation values of 1989) and the Red Sea considers the western the coastal and marine habitats should prove to extremity of the range of this tropical Indo- be useful in future management of the area. Pacific species (Frazier et al., 1987). The This study is a part of a joint project of Khaled Dugong is a rare species and is listed as Bin Sultan Living Oceans Foundation, the Vulnerable (VU) in the IUCN Red List Saudi Wildlife Authority and the Regional (IUCN, 2012). Organization for Conservation of the Red Sea. The project set out to assess and map the Status and ecology of Sirenian…. 3 shallow water habitats of the study area at Results Frasan Bank. The results of the surveys undertaken as a part Methodology of this study can be summarized in table (1) as following: The field work was conducted along the Table.1: Number and habitat types for marine Farasan Bank in the Red Sea (Fig. 1) from the mammals and sea turtle at the study area. th th Number and Habitat type Number of 5 to 28 April 2009. Data was obtained from habitats Individuals both the vessel and underwater surveys using Species SCUBA equipment. The vessel surveys were Common Dolphin Offshore waters around 799 Delphinus delphis the islands and reefs conducted using binoculars with the attempt to Bottlenose dolphin With wide range in 88 Tursiops truncatus sheltered waters to the cover all locations along the Farasan Bank. open ocean The composition of all marine mammal pods Hump-backed Foreshore water near an 2 Dolphin island with mangrove were recorded, identified and photographed. Sousa chinensis swamps Spinner Dolphins Sheltered shallow water 25 The location of the mammals was recorded Stenella longirostris using a Global Positioning System (GPS). The Bryde's whales Offshore patch reefs 2 Balaenoptera edeni identification of recorded marine mammals Dugongs Seagrass beds 2 Dugong dugon and turtles was carried out according to Hawksbill turtles Reefs 22 Eretmochelys Jefferson et al., (2008), and Frazier, et al., imbricata (1987) Green sea turtles Seagrass beds 3 Chelonia mydas Marine turtles were studied using boat surveys and SCUBA equipment to identify individuals and analyze their behaviour during Marine mammals the survey. Underwater surveys were A total of 914 dolphins were sighted in the conducted at eleven sites where habitat type offshore study area distributed among 51 and turtle sightings were recorded. Data were schools ranging between 1 and 80 dolphins. also gathered by visual observation above the Four species of dolphin were recorded viz. the water surface in the study area. Photos were Common Dolphin Delphinus delphis, taken for most of the turtles encountered. Bottlenose Dolphin Tursiops truncatus, the Hump-backed Dolphin Sousa chinensis and In addition to the previous observations, the Spinner dolphin Stenella longirostris. other records on slates and dive logs of turtle Also, three whales were seen, on separate and mammal sightings made by scientists and occasions, two of them were Bryde's whales specialists visiting the area recorded while Balaenoptera edeni, and the third remains boat cursing and diving was also incorporated unidentified. Two dugongs Dugong dugon where possible. were observed in the study area in the shallow The coordinates of marine mammals sighted at sheltered area (see table 1). The distribution of the study area were plotted on a map. sirenian and cetaceans in Farasan Bank is shown in Fig. 1 4 Ahmed Al-Mansi phenomenon. Few sightings of bottlenose dolphins in the shallow water occurred around or in the lagoon of the batch reefs and atolls. The hump-backed dolphins were sighted on one occasion with an observed group of two animals. It was sighted in the foreshore water near an island with mangrove swamps. The Spinner dolphins were also sighted in one Fig. 1. Distribution of the marine mammals in Farasan occasion, in a group including 25 animals. Bank. They were found in sheltered shallow water. The Common dolphin is one of the most The two Bryde's whales were encountered in abundant of all dolphin species (Fig. 2), hence the offshore waters. They were found isolated the name. The individuals of this dolphin can and close to the offshore patch reef which is an be found in warm waters worldwide.