Corals in the Saudi Arabian Gulf Area
Transcription
Corals in the Saudi Arabian Gulf Area
Corals in the Saudi Arabian Gulf Area Pocilloporidae Pocillopora damicornis (L) Stylophora pistillata Esper Astrocoeniidae Madracis kirbyi Veron and Pichon Plate 5.45 Coral grouper, Cephalopholis hemistiktos . Acroporidae Montipora circumvallata (Ehrenberg) ** Montipora spumosa (Lamarck)* Acropora clathrata (Brook) Acropora pharaonis (Edwards and Haime) Acropora valenciennesi (Edwards and Haime) Acropora horrida (Dana) Acropora downingi Wallace Poritidae Porites compressa Dana Porites lutea Edwards & Haime Porites murrayensis Vaughn* Porites nodifera Klunzinger Porites harrisoni Veron Plate 5.46 Psammocora sp. Siderastreidae Siderastrea savignyana Edwards and Haime Pseudosiderastrea tayamai Yabe and Sugiyama Anomastrea irregularis Marenzeller Psammocora haimeana Edwards and Haime Psammocora contigua (Esper) Coscinaraea monile (Forskål) Agariciidae Pavona cactus (Forskål) Pavona diffluens (Lamarck) Pavona explanulata (Lamarck) Pavona varians (Verrill) Pectiniidae Echinophyllia aspera (Ellis and Solander) Mussidae Blastomussa merleti Wells Acanthastrea echinata (Dana) Plate 5.47 Platygyra coral. Merulinidae Hydnophora exesa (Pallas) Faviidae Favia favus (Forskål) Favia pallida (Dana) Favia speciosa Dana* Favites chinensis (Verrill) Favites pentagona (Esper) Platygyra daedalea (Ellis & Solander) Platygyra sinensis (Edwards & Haime) Plesiastrea versipora (Lamarck) Leptastrea inaequalis Klunzinger* Leptastrea purpurea (Dana) Leptastrea transversa Klunzinger Cyphastrea micropthalma (Lamarck) Cyphastrea serialia (Forskål) Plate 5.48 Soft coral, Goniopora djiboutensis. 136 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 136 19/07/12 14:57 Plate 5.49 Porites coral. Rhizangiidae Culicia rubeola (Quoy and Gaimard) Caryophylliidae Paracyathus sp Edwards & Haime Heterocyathus aequicostatus Edwards and Haime Dendrophylliidae Tubastraea aurea (Quoy and Gaimard) Turbinaria mesenterina (Lamarck) Turbinaria peltata (Esper) Psammoseris sp Edwards and Haime The following are listed in Veron’s distribution diagrams as occurring in the Arabian Gulf. Conditions in the extreme East of the Gulf and Musandam are more favorable for corals than locations further West (such as Saudi Arabia). While several of these are possible for Saudi Arabia, especially in the offshore islands, most have no confirmed records. Pocillopora verrucosa (Ellis and Solander) Seriatopora subseriata (Ehrenberg) Seriatopora caliendrum Ehrenberg Montipora foliosa (Pallas) Montipora aequituberculata Bernard Montipora monasteriata (Forskål) Montipora tuberculosa (Lamarck) Montiopora efflorescens Bernard Montipora mollis Bernard Montipora venosa (Ehrenberg) Montipora verrucosa (Lamarck) Acropora nasuta (Dana) Acropora valida (Dana) Astreopora expansa Bruggemann Astreopora myriophthalma (Lamarck) Stylocoeniella guentheri Basset Smith Madracis kirbyi Veron and Pichon Porites solida (Forskål) Porites lobata Dana Porites lichen Dana Gonopora djiboutiensis Vaughan Goniopora lobata Milne Edwards & Haime Goniopora columna Dana Goniopora somaliensis Vaughan Goniopora tenuidens (Quelch) Coscinaraea columna (Dana) Pavona fromdifera (Lamarck) Pavona venosa (Ehrenberg) Pavona decussata (Dana) Pavona duerdeni Vaughan Leptoseris solida (Quelch) Leptoseris mycetoseroides Wells Leptoseris foliosa Dinesen Gardinoseris planulata (Dana) Galaxea fasicularis (L) Cycloseris curvata (Hoeksema) Oxypora lacera (Verrill) Acanthastrea maxima Sheppard and Salm Symphyllia radians Milne Edwards and Haime Symphyllia agaricia Milne Edwards and Haime Hydnophora microconos (Lamarck) Favia rotumana (Gardiner) Favites abdita (Ellis and Solander) Favites complanata (Ehrenberg) Platygyra lamellina (Ehrenberg) Leptoria phrygia (Ellis and Solander) Parasimplastrea sheppardi Veron Echinopora lamellosa (Esper) Echinopora gemmacea Lamarck Euphyllia glabrescens (Chamisso and Eysenhardt) Physogyra lichensteini (Milne Edwards and Haime) Turbinaria reniformis Bernard Heteropsammia cochlea (Splenger) * Records from Burchard but not from Sheppard & Sheppard ** listed previously but doubtful C h a p t e r 5 : S U B T I D A L H A B I T A T S 137 CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 137 19/07/12 14:57 Special aspects to Gulf reefs There are several important constraints on reef development in the Gulf. The coral reefs in the Arabian Gulf are unique in that they are made up of coral species (e.g., Acropora clathrata, Porites cf. compressa, P. nodifera, Cyphastrea microphthalma, Platygyra daedalea, and Siderastrea savignyana) capable of withstanding wide fluctuations in temperature and high salinities, sometimes greater than 45‰ (Kinsman, 1964; Shinn, 1976; Coles, 1988; Sheppard and Sheppard, 1991; KFUPM/RI 1988, 1990). They are routinely exposed to annual ranges of temperature that exceed the temperature extremes reported for the same coral species in any other reef area in the world (Coles, 1988; Coles and Fadlallah, 1991). While remarkable in itself, this does mean that the diversity of corals on them and the general abundance of reefs themselves, is greatly restricted. On the other hand, this does greatly add to their scientific interest. Other physical conditions that affect coral reef distribution, structure, and composition include sedimentation, tidal action, and light (Basson, et al., 1977; IUCN, 1988; KFUPM/RI, 1990). The extreme nature of these physical conditions is the greatest limiting factor of coral reef growth, distribution, and species diversity in the region (Basson, et al., 1977; IUCN, 1988). Because these conditions are more severe bordering the mainland, the majority of the coral reefs occur on offshore islands (Basson, et al., 1977; Coles, 1988; IUCN, 1988). High rates of sedimentation in areas of silty substrate limit coral reef distribution by burying the coral polyps that are needed for filter feeding. The effect of tidal action on coral reefs is reflected in reef structure and species composition (Basson, et al., 1977; Sheppard, et al., 1992). Coral reefs growing on the leeward side of islands typically are steep and vertically compressed; whereas reefs located on the windward side are gradually sloping (Basson, et al., 1977). Light availability plays an important role in coral reef formation. Offshore in the Arabian Gulf, 15-18 meters is the depth limit for continuous coral cover. Where the water is more turbid, for example along the mainland, the depth limit is 10 meters or less (Basson, et al., 1977). This depth limit is due to the light requirement of hermatypic (i.e., true reef forming) corals. Plate 5.50 Sea anemone (Phylum Cnidaria). Plate 5.51 Red coral crab. Plate 5.52 Pharaon cuttlefishes, Sepia pharaonis 138 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 138 19/07/12 14:57 Plate 5.53 Oyster, Family Pectinidae. Oyster Beds Pearl oysters have been fished in the Gulf since ancient times and in the past have been an important component of the economy of the areas in which they occurred, which are primarily the areas along the Arabian side. Wellstead (1838) estimated that at his time of writing (1838), and at the height of each season, over 30.000 people were employed in the collection of oysters for their pearls. By the late 1800s, over 80.000 people were engaged in pearling in the Gulf in one way or another, and an inevitable collapse from over collection then occurred. The year 1917 was the peak for the increasingly industrialized pearling industry, a time which also coincided with the success of the cultured pearl from Japan. Plate 5.54 Oyster in rocks. Plate 5.55 Oyster in sand. Their biology is unusual for bivalve molluscs, because other species of oysters usually form dense reefs,which themselves produce substantial carbonate structures, this is not exactly the case for Pearl oysters which, when mature, live on hard substrates in a more scattered, dispersed way. There are several species present in the region but two are the mainstay of the pearl fishery in the Gulf: Pinctada margaritifera and Pinctada radiata. Pearl oysters are a little unusual in that, while most hard substrate dwelling bivalves remain attached to the same substrate throughout life (unlike several soft substrate species which can flap their valves and move), pearl oysters are capable of some movement when young. In the Western Gulf, settlement of juveniles takes place mainly into seagrass beds in late spring and they also attach in large numbers onto macroalgae, especially onto the large brown algae. On blades of these plants they may be seen in enormously high densities in the form of small but expanding white discs, and they remain on the algae or in the seagrass beds until they are about 5 mm diameter. When the algae or seagrass die they may attach to other living blades or fronds, until eventually they migrate or are tumbled down the slopes into deeper water where they then attach to hard substrates for the rest of their adult lives. There they grow until mature or until collected. Reasons for the decline in the natural pearls include a mass mortality from unknown causes which wiped out most of the stock in the late 1960s (Head, 1987), over collecting and, of course competition with cultured pearls from other countries. Nevertheless, pearl fishing has long been part of the heritage and culture of several countries of the Arabian Gulf which have, therefore, taken steps to preserve this tradition. C h a p t e r 5 : S U B T I D A L H A B I T A T S 139 CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 139 19/07/12 14:58 Muddy and Sandy Substrates Muddy substrates and sandy patches occupy the greater part of the Gulf, mostly below about 6-7 m depth. The coarsest sands and rubble are commonly seen at the foot of reefs and in areas where strong local currents cause sorting of particle size. These habitats support a much lower diversity than do coral reefs but may have an equally high productivity from those species which are found there. In areas where light is sufficient, mostly shallower than 6-7 m depth, there may be substantial seagrass beds, but in deeper water, where light is too dim to support seagrass, secondary productivity is dominant and high. Depending on the coarseness of the grain size, oxygen may not penetrate deeper than a very thin surface film. In sand, the oxygenated layer may penetrate several centimeters deep but in finer mud this is reduced to as little as 1- 2 mm. In general, the deeper the water the finer will be the particles making up the soft sediments, but there are some striking examples in the Gulf where sand deposits occur at considerable depths, at least 30 m, which occur partly because of their proximity to sources of sand, such as reefs, and partly because of strong currents which occur around them. Likewise mud may occur in shallow water, for example adjacent to large muddy tidal flats. Where there is sufficient light there is usually a film of photosynthesizing microalgae on it: diatoms and blue-greens (cyanophytes) which contribute substantial primary production and commonly nitrogen fixation as well. Where light is insufficient, no photosynthesis occurs, and the rain of plankton from the water column above together with organic material brought by currents, provide the primary food source for the sometimes very abundant animal life. Polychaetes worms, crustaceans, molluscs and echinoderms may be locally very abundant. In many areas the dominant species are burrowing forms, such as sand dollars and heart urchins, both of which are echinoderms. Many animals in this area are tiny such as one kind of small clam which may be little bigger than the sand grains it occupies. Others burrow forming tunnels and chambers, whose excavations form small mounds or “volcanoes” covering the seabed. On muddy substrates, bivalves, such as cockles, may live in high density, as do many vast communities of brittle stars. Because of the very high densities of animals that can be found on such substrates, coupled with the fact that these provide substantial food sources for many other species including fish which are of direct interest to humans, it is a mistake to consider the muddy and sandy deeper substrates as being any less important in an ecological sense than the more spectacular shallow systems. They are by no means less important in the total ecosystem of the Gulf. The area of such habitats is vast in comparison to reefs and seagrass areas. These habitats have sometimes been commonly neglected in environmental assessments, for example, perhaps because they are not as attractive or obviously productive as other Gulf benthic habitats, but they are at least as important and provide much of the foundation for the marine life of the Gulf. It is the sum of all these components, hard substrate and soft, which contribute to the rich and integrated ecosystems of the Arabian Gulf. Plate 5.56 Muddy and sandy substrate in Jubail. 140 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f C h a p t e r 5 : S U B T I D A L H A B I T A T S 141 Plate 5.58 Coral grouper, Cephalopholis hemistiktos. Plate 5.59 Cardinalfish, Apogon sp. Plate 5.57 Round coral, Acropora sp. 142 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f Plate 5.60 Stone crab, Carpilus convexus. C h a p t e r 5 : S U B T I D A L H A B I T A T S 143 Plate 5.61 Moon wrasse, Thalassoma lunare. Plate 5.62 Blackspotted rubberlip, Plectorhinchus gaterinus. Plate 5.63 Persian cardinalfish, Cheilodipterus persicus. Plate 5.64 Red Sea Surgeonfish, Acanthurus shoal. 144 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 144 19/07/12 14:58 Plate 5.65 Wrasse fish occur over coral reefs. C h a p t e r 5 : S U B T I D A L H A B I T A T S 145 CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 145 19/07/12 14:58 Plate 5.66 Coral grouper, Cephalopholis hemistiktos. Plate 5.67 Sebae clown fish, Amphiprion sebae, resting on sea anemone tentacle tips. 146 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f Plate 5.68 Lionfish, Pterios miles, Arabic “Deesh”. C h a p t e r 5 : S U B T I D A L H A B I T A T S 147 Plate 5.69 Pharaon cuttlefish, Sepia pharaonis. Plate 5.70 Spotted sole fish. Plate 5.71 Hermit crab. 148 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 148 19/07/12 14:59 Plate 5.72 Arabian butterfly fish, Chaetodon melapterus. Plate 5.73 Black-spotted butterfly fish, Chaetodon nigropunctatus and a lined wrasse. Plate 5.74 Grouper, Subfamily: Epinephelinae, Family: Serranidae. Plate 5.75 Sebae clown fish, Amphiprion sebae. Plate 5.76 Yellowbar angel fish, Pomacanthus maculosus. C h a p t e r 5 : S U B T I D A L H A B I T A T S 149 CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 149 19/07/12 14:59 Plate 5.77 Sea Star, Pentaceratser regulus. 150 M a r i n e A t l a s o f t h e W e s t e r n A r a b i a n G u l f C h a p t e r 5 : S U B T I D A L H A B I T A T S 151 Map 5.1 Subtidal Habitats of the Northern Region. CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 152 19/07/12 14:59 Map 5.2 Subtidal Habitats of the Southern Region. CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 153 13/08/12 13:50 Map 5.3 Subtidal Habitats of the Tanajib-Manifa Embayment. CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 154 19/07/12 14:59 Map 5.4 Subtidal Habitats of Tarut Bay. CHAPTER 5__PART2_FINAL_10MAY2011_jpk_VERONA.indd 155 19/07/12 15:00 Map 5.5 Subtidal Habitats of Abu Ali Embayment.
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