Mannar: Treat with caution

Sri Lanka will shortly submit two environmental proposals to the international community. The first is for the Vankalai Triangle, north west of Sri Lanka to be declared a Ramsar Wetland. The second is for a larger 700,000 hectare marine area in the north west and north east from Kalpitiya and Trincomalee to be declared as a man and biosphere reserve. Here, the Colombo based IUCN Coordinator of the Asia Regional Species Conservation Programme, Dr. Channa Bambaradeniya told The Nation Special why these maritime zones should be protected and highlights the issues in which these zones are engulfed

By Ravi Ladduwahetty
Future development projects in the north west of Sri Lanka will have to tread with caution with moves afoot to get the area declared internationally protected.
This follows a two-pronged proposal. The first is the Sri Lanka Chapter of the World Conservation Union (IUCN), in collaboration with the Ceylon Bird Club, which has proposed that the Vankalai Triangle in north west Sri Lanka be declared a Ramsar wetland. The Vankalai triangle is between Vankalai, Puliyanthivu Island and Tiruketyiswaram, and the Adam’s Bridge islands.
The second, a joint proposal between the Environment Ministry and IUCN, has suggested a larger marine and coastal area spanning 700,000 hectares north of Kalpitiya including Trincomalee Bay, Pigeon Island, the Gulf of Mannar cluster (which includes Palk Bay, Mannar Island, Adams Bridge, Dhanuskodi in Sri Lanka and Rameshwaram in India) be declared as a man and biosphere reserve.
The Sri Lankan sites have been identified as ‘High Regional Priority Areas’ under the National Oceanic and Atmospheric Administration of the United States and IUCN projects on ‘World Heritage Biodiversity.’
The first proposal will be submitted to the Ramsar Secretariat in Switzerland for approval and the second will be submitted to UNESCO for review and declaration as a man and biosphere reserve, IUCN’s Colombo-based Coordinator of the Asia Regional Species Conservation Programme, Dr. Channa Bambaradeniya told The Nation.
Clearance
Therefore, development projects such as the controversial Sethusamudram Canal dredging project already launched by the Tamil Nadu Government, future proposals of the Government of Sri Lanka such as oil exploration, tourism projects in Kalpitiya and fisheries projects would also have to have environmental clearance.
The north western region is renowned for its marine productivity and supports the fisheries community. It is therefore important that the harmful effects on development have to be mitigated and development should consider potential environment impacts on sensitive areas, he said.
Dr. Bambaradeniya explained that scientists were not averse to development programmes but insisted that they be pursued with the minimum impact on the environment.
He cautioned that the sediments from the dredging of the Sethusamudram canal could also impact coral reefs, eco-systems and the sea grass beds, which would in turn affect rich marine fauna. This would also affect fisheries, which Sri Lankans pursue as a livelihood, he said. He also stated there was pearl harvesting in this area four decades ago.
According to Dr. Bambaradeniya, in 1992, an area of 306.7 square kilometres encompassing coral reefs, sandstone reefs, soft bottoms and sea grass beds was declared as the Bar Reef Marine Sanctuary in order to protect threatened sub-tidal ecosystems and associated biodiversity. “However, there is no management of this sanctuary at present and destructive practices continue unabated,” he pointed out.
Among conservation issues and threats to biodiversity have been those of the El Nino effects, which have led to mortality of corals causing immense damage to shallow water coral habitats, and selective harvesting of fish species which have compounded the issues.
Background
The continental shelf around Sri Lanka averages 20 kilometres with it being narrowest in the south of the island. The widest point in the northwest of the island is north of the Kalpitiya peninsula, which lies in the southern Gulf of Mannar, where it ranges from 30 to 60 kilometres.
Sri Lanka’s continental shelf is divisible into a wider inner zone and narrower discontinuous outer zone which is separated by a 55m isobath. The seaward edge of the shelf occurs at a depth of approximately 90 metres.
The shelf edge around the island is covered with a thin layer of organic compounds consisting mainly of calcareous material, shell and coral fragments, worm tubes, echinoderm spines and foraminifera. The inorganic component consists of quartzes, sand and other coarse materials.
The Gulf of Mannar, Palk Strait and Palk Bay areas act as repositories for materials that are swept northwards along the west coast and southwards along the south east coast of India.
Strong currents occur in the Palk Strait between India and Sri Lanka. Velocities of between 2.5-3m/sec are common at Pamban Pass at the Indian end of Adam’s Bridge. High velocities of this nature may contribute to increased sediment transport within this area. The ocean current is driven from the Bay of Bengal to the Arabian Sea during the north-east monsoon and from the Arabian sea to the Bay of Bengal during the south-west monsoon.
Major ecosystems/habitats
The northern and north-western maritime region of the island consists of numerous coastal and marine ecosystems and habitats, in the northern Indian Ocean. These include coral reefs, sea grass beds, mangrove, salt marsh, tidal flats, lagoons, estuaries, sand bars and beach vegetation. The major habitats in the region are as follows:
Coral reefs: The Gulf of Mannar contains the single largest coral reef system in Sri Lanka. Reef habitats in the area constitute of true coral reefs and sandstone reef habitats. The cover on these reefs varies from about 80 percent on good coral reef habitats to less than one percent on some rocky habitats.
True coral reefs can be further categorised into two geologically distinct reef formations as fringing reefs and patch reefs. Fringing reefs are found in shallow water close to the shore, while patch reefs are found further offshore. Fringing reefs are found in the Gulf of Mannar, between the Kalpitiya peninsula and Mannar Island, and around the Jaffna peninsula.
Patch reefs are generally found further offshore, and consist of corals growing on raised humps or ridges on the seabed. Extensive patch reefs exist in the Gulf of Mannar, particularly within the Bar Reef Marine Sanctuary and further northwards towards Mannar (Ohman et al., 1993).
Coral reefs around the Jaffna Peninsula occur mainly around the small coastal islets, but they are not extensively developed. Barrier coral reefs, consisting of ridges of coral lying some distance from the shore, parallel with it and forming a broad ‘reef lagoon’ are found at Vankalai and Silavathurai in the north western coast.
Sea grass beds: Extensive sea grass beds have been reported from the Dutch Bay (in Kalpitiya) to the western end of the Jaffna Peninsula, and from Mannar to the northwest across the Palk Bay to Rameshwaram Island on the Indian coast. The sea grass beds in the Palk Bay-Gulf of Mannar area are the main habitats of the globally endangered Dugong.
Salt marshes: A salt marsh is an inter tidal complex plant community dominated by herbs (up to 0.5m) and low growing shrubs (0.75m). Extensive salt marshes occur in the Mannar area (mainly on tidal flats and containing about 56 species of marsh vegetation) in the coastal belt from Mantai to Vankalai.
Mangroves: Mangroves are salt-tolerant woody plant assemblages located along sheltered lagoons, estuaries and near-shore islets. The mangrove vegetation in the islands off Kalpitiya peninsula is dominated by Rhizophora mucronata. The dominant mangrove vegetation in the Mannar region include Avicennia marina, Aegiceras corniculatum and Excoecaria agallocha, which are characteristic species in high-saline mangrove forests.
Rich invertebrate species: Sri Lanka’s reefs support a high invertebrate species diversity consisting of all major groups such as stony corals, soft corals, anemones, polychaetes, sponges, tunicates, spiny lobsters and other crustaceans, molluscs, and echinoderms.
Rich vertebrate species: The relatively shallow marine environment in this region, including its complex habitats such as sea-grass beds, mangroves, lagoons and coral reefs, have contributed to a high richness of marine and brackish water fish species.
More than 300 reefs and reef associated fish species excluding cryptic species such as gobies and blennies have been identified from the Bar Reef Marine Sanctuary Major piscivores such as Groupers (Serranidae), Barracudas (Spyraenidae), Jacks (Carangidae) Black-tip Reef Sharks (Carcharhinus melanopterus) and White-tip Reef Sharks (Triaenodon obesus) have also been recorded from this area. More than 40 species of marine and brackish water fish species have been recorded from the Kalpitiya North marine area
Three species of marine turtles have been recorded in the Gulf of Mannar region. The predominant species is the Olive Ridley (Lepidochelys olvaceae), followed by the Green Turtle (Chelonia mydas) and the Hawksbill Turtle (Erytmochelis imbricata). All three species are considered to be globally threatened.
The Gulf of Mannar area is known to be an important foraging site and a migratory route of the Olive Ridley population inhabiting the South Asian marine region (Kapurusinghe and Cooray, 2002). These migrate annually to the beaches of Orissa, which is known to be their largest known nesting site in the world. Other marine reptiles documented from the north-western marine waters include sea snakes, such as the hook-nosed sea snake (Enhydrina schistosa).
High significance
According to observations made by the Ceylon Bird Club (CBC), the Mannar region, including Talaimannar and Adam’s Bridge are important refuges of water birds, especially the annual migrants. The Gulf of Mannar region forms part of the Central-South Asian migratory bird flyway. As such the island habitats of this area are of high ecological significance for annual migrants.
A total of 166,300 water birds were recorded from this region in 2003, during the annual water bird census conducted by the CBC. These include numerous species of resident as well as migratory waterfowl and waders.
The Ceylon Bird Club has identified a triangular area in this region (covering Vankalai, Puliyantivu Island, and Tiruketiswaram) and the Adam’s Bridge islands as important bird habitats. The marine area north of Kalpitiya, including the islands, is also an important habitat of water birds.
Twelve species of marine mammals have been documented within the north western maritime zone of Sri Lanka; the species are globally threatened.
Many researchers have documented cetaceans in the vicinity of the Bar Reef Marine Sanctuary, which is located in the Southern Gulf of Mannar. The population of the globally endangered Dugong has been documented within the extensive sea grass beds north of the Kalpitiya peninsula.
A recent survey of the Bar Reef Sanctuary indicated that it possesses year round abundance and species richness of marine mammals and suggests that the northern and central area may be considered a cetacean ‘hotspot.’
Additionally, a previous survey conducted within the southern Gulf of Mannar during the Voyage of the Odyssey, highlighted the possibility that this area may be a breeding ground for at least one species of large whale.
Socio-economic
significance
In addition to a thriving fisheries industry that supplies the local market, export-oriented fisheries targetting high-value invertebrates such as shrimp, lobster, chank, sea cucumber, etc., take place in the north western marine region.
Reef and reef-associated fisheries are the main economic use of reefs in Sri Lanka. The fishery sector contributes about 2% to the GDP. Reef fish production fluctuates yearly, but yields an average annual catch of around 10,000 tonnes, which constitutes about 72% of total marine fish production. The spiny lobster harvest in 1994 was 1,000 tonnes. Major activities in the coastal fisheries sector within the Gulf of Mannar and Palk Bay are spiny lobster fish and the marine ornamental fish, almost all of which are dependent on reef habitats. Sea cucumber and sacred chanks are harvested in soft bottom areas between patch reefs. Ornamental fish, sea cucumber and chanks are harvested exclusively for export, while most of the spiny lobster catch is also exported.
In 1992, an area of 306.7 sq. km encompassing coral reefs, sandstone reefs, soft bottoms and sea grass beds was declared as the Bar Reef Marine Sanctuary in order to protect threatened sub-tidal ecosystems and associated biodiversity. However, there is no management of this sanctuary at present and destructive practices continue unabated.
Conservation issues
El Nino effects: In 1998, an increase in seawater temperatures caused by the El Nino Southern Oscillation (ENSO) led to massive coral bleaching and mortality of corals in the Indian Ocean. This event caused immense damage to shallow water coral habitats in Sri Lanka.
Selective over-harvesting: Selective harvesting of species is commonly practiced in the north western region. For instance, the sea cucumber fishery selectively harvests only one species, Holothuria scabra. Similarly, the ornamental fish collectors mainly target the high valued species. In the long term, such practices of unregulated selective over-harvesting may be detrimental to the resource.
By-catch and deliberate killing: Incidental by-catch is a serious conservation issue in the north western marine area of Sri Lanka affecting the populations of marine mammals and marine turtles. Entanglement of turtles is reported in both small and large mesh gillnets fisheries and the tuna long line fishery. Endangered marine mammals such as Dugong are also killed deliberately by local fishermen in the north western area, since their meat fetches a high price in local markets.

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Continental shelf morphology within the northern and north-western marine area

Location Principal depths (m) Shelf Edge (m) Shelf width (km)
Adam’s Bridge <15 18-45 20
Gulf of Mannar <15 22-45 30-40
Point Pedro <60 119 60

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Marine mammals of the Gulf of Mannar checklist

Scientific name Common name
Balaenoptera musculus Blue whale (T)
Balaenoptera acustorostrata Minke whale
Megaptera novaeangliae Humpback whale (T)
Physeter macrocephalus Sperm whale (T)
Kogia sima Dwarf Sperm whale
Pseudorca crassidens False Killer whale
Peponocephala electra Melon-headed whale
Sousa chinensis Indo-Pacific Humpback Dolphin
Delphinus delphis Common Dolphin
Stenella longirostris Long-snouted Spinner Dolphin
Stenella attenuate Pan-tropical spotted Dolphin
Dugong Dugon Dugong (T)
(T) – Globally threatened (IUCN, 2004)

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