Islands in Gulf of Mannar shifting?

TUTICORIN, MAY 8. Four of the 20 islands, along the stretch of Gulf of Mannar (GoM) which is declared as a National Marine Park (NMP), have been migrating due to industrial pollution and indiscriminate exploitation of stony corals which formed the foundation of these islands.

Dr. N. Ramanujam, Geologist and Head of Post Graduate Department of Geology and Research Centre, V.O. Chidambaram College, told TheHindu that the mining of the corals around the islands would lead to disastrous consequences as the discontinuous chain of 20 islands extending 150 km from Tuticorin to Adams Bridge protected the low lands of Ramanathapuram and Tuticorin districts from cyclonic effects.

All the 20 islands were transferred to the wildlife wing of the State Government in 1991-92. Much before that, the Government, through a notification in 1980 expressed its intention to establish an NMP in the GoM for the protection of wildlife and environment. The area was declared a Biosphere Reserve in 1989.

The islands in the GoM region had been broadly classified as Tuticorin, Vembar, Keelakarai and Mandapam groups. Destruction of the coral reef eco-system in the region, particularly the instability and deterioration of the Tuticorin group of islands - Van, Koswari, Vilangushuli and Kariashuli - had always been a cause of concern to scientists.

The related issues were discussed in various research for including the workshop on `Biodiversity of Gulf of Mannar Biosphere Reserve' held at M.S. Swaminathan Research Foundation and the International workshop on Environmental Biochemistry held in the Jawaharlal Nehru University, New Delhi, a couple of years ago, he said.

A recent field study conducted by a team of scholars including Dr. Ramanujam and Dr. M. V. Mukesh on the changes in the size, shape, orientation and migration of the Tuticorin group of islands had revealed that there were significant changes in the reef and islands' geomorphology.

For instance, the reef rim topography of the Van Island had become irregular due to mining of reef materials. This was one of the major factors contributing to its instability and migration. Since 1920, the Van Island had migrated 1.72 km in northwest direction towards the main land.

As far as the Koswari Island was concerned, continuous reef material exploitation had hindered sediment supply for the construction of the island. In the case of Vilangushuli Island, miners had totally blasted the reef rim. The direct wave attack eroded and levelled the island below the mean sea level. In the Kariashuli Island, the consolidated and rocky materials and also loose and unconsolidated coral sand and gravel were mined in the windward side of the island, Dr. Ramanujam said.

Showing scant regard for law including the Wildlife (Protection) Act 1972, Environment (Protection) Act 1986 and the Tamil Nadu Forest Act 1882, anti-social elements continued with their illegal and uncontrolled quarrying of the coral reefs for construction, industrial and chemical purposes, he pointed out.

According to him, the indiscriminate use of the coral reefs actually began five decades ago and even today the exploitation went on at the rate of about 100 tonnes per day. Destruction of the reef amounted to 15,000 tonnes of boulders and 10,000 tonnes of coral debris annually. As many as 500 skilled and semi-skilled divers were engaged in the collection of a variety of reef- associated shells and chanks, besides harvesting marine algae from the reef area.

The study also revealed that the use of various types of fishing techniques such as fishing traps, bottom trawls and dynamite fishing also caused irreparable damage. Mining had threatened the integrity of the mangrove and seagrass too.

Added to this, several chemical industries in the hinterland like the petrochemical, thermal and heavy water plants discharged their toxic effluents into the sea causing a devastating effect on the eco-system around the islands, he said. ``Construction of the breakwaters in the Tuticorin harbour area had also changed the current flow pattern and sediment movement along the coast.''

Calling for steps to protect the ``fragile system,'' Dr. Ramanujam said the most effective way was to create awareness among all the concerned, including the local people, fishing folk and the industries so that they recognised the area as a prospective zone of potential resource which should be protected for the benefit of mankind.