The Indian Ocean region is a large, biologically diverse area bordered by many countries (Map 3). Regional human population growth is a major threat to coral reef ecosystem health as many reefs are located near large population centers. It is estimated that over 20 percent of the coral reefs and five percent of the seagrass beds have been destroyed (IUCN/UNEP, 1985). The use of illegal fishing methods (dynamite, poisons, intoxi-cants) is widespread (IUCN/UNEP, 1988). Few scientific studies exist to document the extent of damage.
In East Africa total mangrove area is about 600,000-1,200,000 ha, and distribution is correlated with coastal indentation and large river discharge. Over-exploitation and the lack of expertise and institutional management capacity threaten their existence. Seagrass beds are found throughout the region and are under pressure from intensive use of bottom traps and beach seines, explosives fishing, sand mining and dredging (GBRMPA et al., in press). Coral reefs are important sources of food for local human populations and are of major commercial importance for fisheries and tourism. The Somali coast has few reefs due to seasonal cool upwelling and those that do occur are not well-developed (except for the southern coast and adjacent Bajuni Islands where reefs are well developed). Some patch reefs occur off Mogadishu. Well-developed fringing and patch reefs occur off Tanzania, are close to shore, and are only discontinuous where large rivers meet the sea. Reefs are also found around Mafia and Zanzibar Islands. Reefs off Kenya and Mozambique have similar limitations. Extensive reefs of all types exist off Madagascar. Mauritius, Reunion, and Comoros Islands also have fringing reefs. Small fringing reefs are most common around the Seychelles Islands along with a few atolls such as Aldabra where reef formations are spectacular. Over-exploitation of fishery resources has been reported from Tanzania and Mauritius; and reefs off Kenya, Tanzania, and Mauritius suffer from destructive fishing practices. Trampling of coral by fishermen have also degraded reefs in the region. Coral and coral sand mining in Mafia (Tanzania), Comoros, Mauritius, and Madagascar has damaged reefs. Over 500,000 tons of coral sand are excavated annually from Mauritius, and most beaches in Comoros have been scarred by sand mining. Over 250 tons of shells and corals were exported from Tanzania in 1974. Exploitive collection has moved from the depleted areas off Tanzania and Kenya to the islands of Zanzibar and Mafia. Sedimentation from agricultural practices is a major problem throughout the region. The problem is critical in Comoros and has also affected reefs off the Seychelles, Dar es Salaam, and Zanzibar. Eutrophication is a problem in Port Louise, Dar es Salaam, and Zanzibar (Mohammed, 1994).
The northern Indian Ocean is divided by India, forming the Arabian Sea and the Bay of Bengal. The Bay of Bengal, the Sunderbans, and the Ganges delta support over 500,000 ha of mangrove. India supports about 100,000-700,000 ha. Mangroves are not as abundant in Sri Lanka (10,000 - 12,000 ha) and are patchy in the atoll islands of the area. Mangroves are economically very valuable in the area and are used heavily. Since 1963 about 50 percent of India's mangroves have been destroyed. Extensive seagrass beds are found in southern India and in the many estuaries of Sri Lanka where they cover an area greater than that covered by mangroves and coral reefs, make the largest contribution to primary productivity in coastal waters, and support over 50 percent of the countries coastal fishery production. The degree of exposure and water turbidity limit the extent of seagrasses in western India and populations are negligible off Bangladesh because of seasonal fluctuations in salinity. Seagrasses are also limited off the Maldives (GBRMPA et al., in press). Most coral reef growth is inhibited by fresh water and sedimentary deposits from rivers. Bangladesh and Pakistan lack reefs although there are isolated colonies. There is relatively poor reef growth on the west coast of India, mainly in the Gulf of Kutch. Reef growth becomes more vigorous towards the southern tip of India and around the coast of Sri Lanka (Wells, 1993). Like the East African region, countries such as Myanmar, Thailand, India, and Sri Lanka suffer from over-fishing/over-collecting, tourism, mining, and industrial growth (IUCN/UNEP, 1988). Sri Lanka has been especially prone to over-exploitation as over one-third of the population lives in coastal areas and on average 65 percent of the national animal protein comes from marine sources (almost 100 percent for coastal areas). Coral mining is especially serious in the Maldives (used for road construction), Sri Lanka, and India where tens of thousands of tons are removed annually. Deteriorating fish populations force fishermen to travel further to find productive spots and the aquarium fish industry threatens populations off Sri Lanka and the Maldives (Öhman et al., 1993).
Most reefs in the eastern Indian Ocean are found offshore. Chagos, a group of coral-covered banks, reefs, atolls, and fringed coralline islands is located in the central part of the Indian Ocean and contains the best developed, most pristine, and greatest variety of reefs in the Central-Western Indian Ocean. Some of the reefs at Diego Garcia have been affected by dredging for construction associated with the large military presence.
Coral reef ecosystem degradation would have serious impacts on food supply for local inhabitants and major economic impacts for the fishing, aquarium, and tourist industries.
Existing Management and Research Programs
The UNEP Eastern African Coastal and Marine Environment Resources Database and Atlas Project is producing a GIS covering East Africa and western Indian Ocean Islands. Several marine reserves were designated in Tanzania, but exist on paper only, and a recent addition off Zanzibar (gazetted in December 1994) is under private management. Two reserves exist in Mozambique (Bazaruto National Park and Inhaca Island Marine Reserve). Several areas have been designated around Mahe and adjacent islands. Aldabra is a World Heritage Site. A few areas have been recommended for protection around Mauritius. Reefs are also protected in the Flacq and Black River fishing reserves (Mohammed, 1994). Four coral reef marine parks and five marine reserves exist and are well managed in Kenyan waters, and have been useful in showing the decline of species in non-protected areas (McClanahan and Obura, 1993).
The National Aquatic Resources Agency was formed in 1981 to conduct research and manage all aquatic resources in Sri Lanka and a Coral Reef Research Program was established in 1985 to monitor and recommend management strategies for reefs. Two marine sanctuaries have been establish in Sri Lanka waters (Hikkadaduwa and Bar Reef) but are not managed (Rajasururiya, 1993). In some cases (coral mining), the Coastal Conservation Act of Sri Lanka has been hard to implement because of traditional use barriers and lack of alternative employment. In Sri Lanka cooperative programs have been established with the U.S. Agency for International Development (USAID) and the University of Rhode Island to develop public education in reef conservation (Wells, 1993).
The University of Reunion, University of Mauritius, Kenya Marine & Fisheries Research Institute, Institute of Marine Sciences University of Dar es Salaam, Tanzania (with research Station on Zanzibar) and the University of Toliara Marine Station, Madagascar all conduct research on coral reef ecosystems.
Preliminary Recommendations for Regional Action
In addition to the general global recommendations, we suggest the following:
Integrated Coastal Zone Management
- Prohibit destructive fishing methods i.e., lead line anchored set nets;
- Control collection and exportation of aquarium fishes and invertebrates; and
- Create alternative employment programs for communities dependent on the destructive consumption (coral mining) of coral reef resources.
- Train personnel to plan and implement research and conservation programs; and
- Provide public sustainable use education.
Improved Scientific Understanding of Coral Reef Ecosystems
- Encourage more coral reef research in the region.
State of the Reefs * May 1995