English abstract
In the Sultanate of Oman, major coral growth is restricted to four areas the Musandam Peninsula (Arabian Gulf coast), the rocky shores, bays and islands in and adjacent to the Muscat area (Gulf of Oman, including the Dimaniyat Islands, Sawadi Area and Fahal Island); the straits, shallows and shores west of Masirah Island (Arabian Sea), and some isolated sheltered locations in Dhofar and the Al Hallaniyats (Arabian Sea). Threats to coral reefs include temperature-drops upwelling-related factors, especially turbidity, sodiment characteristics, which may not enhance larval setllement of coral communities, strong currents, biotic relationships, in particular deplection of corals by predators, such as starfish Acanthaster planci, and descases, and finally human disturbances. Therefore there is a need for rehabilitation of the coral reefs of Oman. Artificial reef structures have been deployed in the Muscat arca, especially in Fahal Island, after observation of damage to the coral reef. In the present study (2000-2003), coral communities in Fahal Island were studied at two depth levels (4m and 16m), along two transects (Transect 1 with artificial reef structures - pallet balls, and Transect 2 with coral communities on natural substrate). Effects of currents on coral settlement on pallet balls, and coral growth of Acropora sp. colonies growing on pallet balls were also studied. Results of coral communities were based on non-destructive videomonitoring of quadrat arcas along the two transects, and the two depth levels. A total of 31 coral species were identified at the sites. At 16 m depth, coral communities were more diverse, either on natural or on artificial substrates, although they were less dense. Multivariate analysis showed that coral communities settling on pallet balls were distinct from those on natural substrate. Analysis of sediment particles in the area also showed that this it is an area of relatively high exposure, so that corals may have difficulty in settlement Thus, the deployment of artificial reef structures provided more stable and additional substrate for corals species, especially incrusting corals, and obviously for other benthic organisms. Results also showed that Acropora sp. colonies on artificial substrate at the 4 m depth level did grow both horizontally and vertically at a rate of about 6 mm/month or 7 em/year. Coral disposition on pallet balls also showed that corals did not preferentially settled on a particular side of the reef ball structures, but were spread all over the artificial structure, showing that the currents' strength had no effect on coral settlement on pallet balls, or most likely, the effect is felt equally in all directions.
