An Unnatural Disaster

Clearing India's Mangrove Forests Has Left The Coast Defenseless

The thousands of people who died when a cyclone struck the eastern coast of  India last weekend could have been saved if mangrove forests had not been destroyed to make way for shrimp farms, according to coastal geographers. For info on the The Mangrove Action Project see below.

The cyclone came ashore from the Bay of Bengal and ripped through the coastal state of Orissa, with winds of up to 300 kilometers per hour. Early reports said that the accompanying tidal surge, coupled with torrential rain and burst river banks, flooded the flat coastal region and the delta of the River Mahanadi in head height for up to 13 kilometers inland. Slums in the state capital, Bhubaneshwar, 50 kilometers from the coast, were washed away.

"This coastline was once covered by mangrove forests," says Tom Spencer of the Cambridge Coastal Research Unit at Cambridge University. "In the past, the mangroves would have dissipated the incoming wave energy." Mangroves grow on tidal coasts between the high and low-water marks. They trap sediment in their roots, which gives the seabed a shallow shape. This absorbs the energy of waves and tidal surges, protecting the land behind. The trees themselves also form a barrier against wind.

In the past 40 years, India has lost more than half of its mangrove forests. "The mangroves in Orissa have been mostly destroyed, says Spencer. This has left it wide open to attack by the wind and waves of the cyclones that regularly lash the coast of eastern India and neighboring Bangladesh.

"I am quite sure the loss of the mangroves was a contributory factor in the extent of the damage," says Spencer. The problem is that the mangroves make ideal places for conversion into ponds for shrimp farming. This lucrative form of aquaculture is one of the fastest growing businesses in the world, and India is one of the top four exporters, with production growing by 15% a year. Orissa, a major centre of the business, specializes in raising tiger prawns.

Three years ago, India's Supreme Court ordered the closure of large shrimp farms within 500 meters of the high tide mark (New Scientist 21, December 1996, p. 8). It ruled that they were encouraging the penetration of salt into coastal water supplies and rice paddies, as well as polluting the lands with pesticides. But despite the move, the lucrative business continues to grow. The death and destruction in Orissa may prompt a reappraisal.

Source: New Scientist, Nov.6


The Mangrove Action Project

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Mangrove forests are one of the most productive and biodiverse wetlands on earth. Yet, these unique coastal tropical forests are among the most threatened habitats in the world. They may be disappearing more quickly than inland tropical rainforests, and so far, with little public notice. Growing in the intertidal areas and estuary mouths between land and sea, mangroves provide critical habitat for a diverse marine and terrestrial flora and fauna. Healthy mangrove forests are key to a healthy marine ecology.

Alfredo Quarto, Executive Director
Mangrove Action Project
PO Box 1854
Port Angeles, WA 98362-0279
fax (360) 452-5866
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