The Gulf of Mannar

( மன்னார் வளைகுடா)

The Gulf of Mannar(Tamil: மன்னார் வளைகுடா) is a large shallow bay forming part of the Laccadive Sea in theIndian Ocean. It lies between the southeastern tip of Indiaand the west coast of Sri Lanka, in theCoromandel CoastRegion.

A chain of low islands and reefs known asAdam's Bridge, also called Ramsethu, which includes Mannar Island, separates the Gulf of Mannar from Palk Bay, which lies to the north between India and Sri Lanka. The estuaries of Thamirabarani River of south India and the Malvathu Oya (Malvathu River) of Sri Lanka drain into the Gulf

Marine sanctuary

Located on the southeastern tip of the subcontinent, the Gulf of Mannar is known to harbour over 3,600 species of flora and fauna, making it one of the richest coastal regions in Asia. 117 hard coral species have been recorded in the Gulf of Mannar. Sea turtles are frequent visitors to the gulf as are sharks, dugongs, and dolphins. However, the combined effects of 47 villages, with a total population of around 50,000 has meant that overharvesting of marine species has become a problem. Fish catches have declined, as have pearl  oyster,  gorgonian  coral, and  acorn  worm populations. Local fishermen rely on the reef to feed their families, but destructive fishing methods combined with the stress of pollution and coral mining have meant both near shore and offshore catches have decreased. Endangered species include dolphins,   dugongs,  whales and sea cucumbers.

In 1986, a group of 21 islets lying off the Tamil Nadu coast betweenThoothukudi and Dhanushkodi were declared the Gulf of Mannar Marine National Park. The park and its 10 km buffer zone were declared a Biosphere Reserve in 1989.

Biosphere reserve

The Gulf of Mannar Biosphere Reserve covers an area of 10,500 km² of ocean, islands and the adjoining coastline. The islets and coastal buffer zone includes beaches, estuaries, and tropical dry broadleaf forests, while the marine environments include seaweed communities,sea grass communities, coral reefs, salt marshes and mangroveforests.

Marine activities

The Gulf of Mannar is known for its pearl banks of Pinctada radiata and Pinctada fucatafor at least two thousand years. Pliny the Elder (23–79) praised the pearl fishery of the gulf as most productive in the world. Although extraction of natural pearls is considered too expensive in most parts of the world, it is still conducted in the gulf.

         The chief seaports on the Gulf of Mannar are Thoothukudi (Tuticorin) in Tamil Nadu, and Colombo in Sri Lanka. While these ports can accommodate deep-draft vessels, the shallow Palk Strait can only accommodate small shallow-draft vessels. In July 2005, the Indian Government took preliminary steps to go ahead with the Sethusamudram Shipping Canal Project, which would create a deep channel linking the Gulf of Mannar to the Bay of Bengal. Project boosters emphasize the benefits of a direct shipping route that connects India's east and west coasts without the long trip around Sri Lanka; environmentalists have warned against the grave damage such a project could cause to the sea life and fisheries of the Palk Strait and the Gulf.

The Gulf of Mannar Marine National Park  (மன்னார்  வளைகுடா தேசிய கடல்சார் உயிரியல் பூங்கா)

   The Gulf of Mannar Marine National Park is a protected area of India consisting of 21 small islands (islets) and adjacentcoral reefs in theGulf of Mannar in the Indian Ocean. It lies 1 to 10 km away from the east coast of Tamil Nadu, South Indiafor 160 km between Thoothukudi (Tuticorin) and Dhanushkodi. It is the core area of theGulf of Mannar Biosphere Reserve which includes a 10 km buffer zone around the park, including the populated coastal area. The park has a high diversity of plants and animals in its marine, inter tidaland near shore habitats. Public access inside the Park is limited to glass bottom boat rides.

Flora and fauna

Clownfish

The park includes estuaries, mudflats, beach sand forests of the near shore environment. It also includes marine components such as coral reefs, seaweed communities, sea grasses, salt marshes and mangroves. 

Flora – Mangroves dominate the intertidal zones of the park islands. They consist of species belonging to the Rhizophora,  Avicennia, Bruguiera,  Ceriops and Lumnitzera genus.

 Introduced Prosopis genus of tree species are dominant on land in all the islands. Pemphis acidula (Lythraceae family of flowering herb) is the only endemic plant species. 12 species of sea grass and 147 species of seaweeds were recorded. This vegetation provides important feeding grounds for the vulnerable marine mammal, the Dugong, endangered Green turtles and Olive Ridley turtles.

Fauna

Vertebrates

Dugong, a vulnerable marine mammal is the flagship mammal of the park. It is an important habitat for the Cetaceans: Indo-Pacific bottlenose dolphin, Finless porpoise, Spinner dolphin, Common dolphin, Risso's dolphin, Melon-headed whale, and Dwarf sperm whale. Larger whales include Sperm whale, Minke whale, Bryde's whale, Sei whale, and critically endangered species including Humpback whale, Fin whale, and Blue whale.

About 510 (23%) of the 2,200 fin fish species in Indian waters are found in the Gulf, making it the most highly diverse fish habitat in India. Coral associated ornamental fishes belonging to the family Chaetodontidae, (butterfly fish); Parrotfish; Amphiprion spp (clown fish), Holocentrus spp (squirrel fish), Scarus spp (parrot fish), Lutjanus spp (snappers) and Abudefduf saxatilis (sergeant Major) are abundant.

A unique endemic species of Balanoglossus – Ptychodera fluva, a living fossil that links invertebrates and vertebrates, has been recorded only at Kurusadai.

Invertebrates

Four species each of shrimp and lobster, 106 species of crab, 17 species of sea cucumber, and 466 species of mollusc including 271gastropods, 174 bivalves, 5 polyplacophorans, 16 cephalopods and 5scaphopods, 108 species of sponge, and 100 species ofechinoderm occur in the Gulf.

The coral fauna includes 106 species from 30 genus of hermatypesand 11 species from 10 genus of ahermatypes, including 13 new species, giving a total of 117 species from 14 families and 40 genus. The reefs in this area are narrow fringing reefs located 150 to 300 m. from the shore of the islands and patch reefs rising up from depths of 2 to 9 m. and extending up to 2 km. long and 50 m. wide. Large areas of these reefs are in generally poor condition due to destructive human activities of the 150,000 persons living along the coast. Nutrient and other pollution loads are high due to agriculture, deforestation, industry, urbanization and septic pollution. It appears that the Coral reefs of the Gulf of Mannar Marine National Park seem to be healthy and in good condition, despite high rates of sedimentation and other threats. However, live coral cover is only about 35%. Various algae cover much of the dead coral.

Stony coral species belonging to Poritidae and Faviidae sub orders constitute the dominant reef builders here. Coral reefs near some of the islands have been heavily damaged by exploitation as raw materials for industrial ventures such as cement industries, brick manufacture, masonry work and lime kilns. Though legal quarrying of the reefs is now stopped, up to 250 m³/day of reef were destroyed for many years.

Habitation

The islands are uninhabited except for Krusadai, Musal and Nallathanni islands where antipoaching sheds are operating.Along the coast near the park there are about 125 villages which support about 100,000 people who are mainlyMarakeyars, a local community principally engaged in fishing.

Habitat Degradation

Experts say that Vaan Island, one of the four islands of the Tuticorn group, has split in two and if immediate efforts are not taken then the island would soon vanish under the sea. Vaan Island, which is the southernmost of the 21 islands in the Gulf of Mannar, was initially spread across 16 hectares, but had shrunk alarmingly by around 10.3 hectares to its current 5.7 hectares in less than three decades. According to J K Patterson Edward, director of Suganthi Devadasan Marine Research Institute (SDMRI), Tuticorin,"Rampant coral mining by people of the fishing villages along the coast is the main cause of the devastation to the island. Coral mining was banned in 2005, but the damage had already been done." Two of the 21 islands have already submerged around a decade ago.

Visitor information

Glass-bottomed boats available at Mandapam cater to tourists visiting the area. Access to the islands is prohibited. The nearest railway stations are at Mandapam and Tuticorin.

SOURCE: WIKI