THE mangrove forest ecosystem alongthe Tamil Nadu coast faces threat due torampant human intervention, prawnfarming and the changed dynamics ofthe flow in the Cauvery river system.The ministry of environment andforests status report, 1987, states thatIndia has a total mangrove forest area of6,740 sq km. Of this, the east coast has70 per cent of the nation's mangrovearea. Tamil Nadu reportedly has 150 sqkm of mangrove forests. These are predominant in the alluvial delta of theCauvery near Muthupettai in Nagai-Quaid-De-Milleth district andPitchavaram. coastal area in south Arcotdistrict.
Muthupettai has a total mangroveforest area of 12,425 ha, of which, 6,003ha are reserved forests. These are beingcleared for prawn farming. Mangrovetrees are felled in large numbers andused as fuelwood for domestic purposes,hotels and for brick kilns. Under suchpressures, the MuthupettaiEnvironment Conservation Society wasformed to preserve the mangroveforests. Teastall owners, brick kiln operators and women were appealed not touse the fuelwood from mangrove trees.
Muthupettai has been home to 56plant species of which the importantones are Avicennia marina, A officinalis,Excoecaria aqallocha, Saueda maritimaand Acanthus illicifolius. Now, soil erosion in Cauvery's catchment area andreduced waterflow is gravely affectingthe Muthupettai mangrove ecosystem.
Abdul Rahman, head, departmentof zoology, AVVM Sri Pushpam College,Poondi, says, "Heavy sedimentation istaking place in the mouth of Koraiyarriver. Low-lying areas are elevated. Newmangroves come up in the resultingmicrodeltas. Since access to the sea isaffected, fisherfolk congregate inlagoons, thereby affecting the nurseryground of fish and prawns. To facilitate river flow into the sea and seawater flowduring high tide, necessary dredgingshould be undertaken. Prawn farms areusing saline water on large scale in thelagoon area. Also, while pumping thewater from the lagoon, small organismswere destroyed in the sieve attached tothe pipes. Taking saline water fromlagoons for prawn farms should therefore be banned. If this two-prongedaction is not taken, within 10 years wewill have the forest area devoid ofwater."
In Pitchavararn - constituted of 51small islets - the pressure is mainly dueto tourism and cattle grazing, which issaid to arrest sapling growth. Eighty-sixplant-', vrawn and more than58 fish species were identified in the region. The forest area is spread over 1,100 ha. But according to the satelliteimagery obtained in 1993, the actualforest area has dwindled to 147 ha.