THEKKADY, JAN. 7. The raising of the water level in the Mullapperiyar reservoir may reduce the population of tigers and elephants in the Periyar Tiger Reserve. Because, it will lead to submergence - caused by the rise in the water level of Periyar Lake as a fallout of the rise in the water level of reservoir from the present 136 feet to 152 feet - of the grasslands and marshy land on the lake fringe.

(The lake fringe is a major hunting ground for tigers as it is home to a large number of animals especially the sambar deer which is the tiger's staple diet, say the scientists.)

According to the scientists, the rise in the water level of the Periyar Lake will cause heavy damage to the biodiversity of the 777-square km-Periyar Tiger Reserve, the largest protected area in Kerala. The loss of feeding and hunting ground would lead to the migration or reduction in the population of wild boars, gaurs, sambars, otters and many smaller mammals apart from destruction of several species of flora. Many species of water birds that build nests on the dead trees that stick out of the Periyar Lake may also leave if the water level rises to grab their nests.

The Advocate General of Kerala, M. Ratna Singh, recently suggested to the State Government to go in for a legislation to restrict the water level because of the chances of the breakdown of the 106-year-old dam. But the political leaders have been oblivious to the impact on biodiversity.

(The Tamil Nadu Government insists on raising the level to 152 feet; the high-level committee, appointed by the Central Government, has recommended an initial raising up to 142 feet and, after the strengthening of the `baby dam,' to the full level; but the Kerala Government wants the level to be pegged at 136 feet at which the dam has survived for about three decades. The level was brought down to 136 from 152 in the 1970s.)

Biodiversity loss

A study on the `Impact of raising of water level in the Mullapperiyar reservoir of the Periyar Tiger Reserve' carried out a few months back at the instance of the Chief Wildlife Warden of Kerala concluded that a higher water level in the lake would lead to a drastic reduction in the wealth of flora and fauna.

The study team included scientists from the Kerala Forest Research Institute, Tropical Botanic Garden and Research Institute, Centre for Water Resource Development and Management and Salim Ali Centre for Ornithology and Natural History as well as an ecologist and a sociologist from the Periyar Tiger Reserve.

The report points out that carnivorous animals, especially the tiger and wild boar, use the lake fringes for hunting. The submergence of additional areas, including `vayals' - the most preferred habitat of herbivorous like sambar deer - and the resultant changes would force the herbivorous animals to move further interior affecting the prey-predator relationship. ``The changes may get years to get stabilised and can lead to highly unpredictable adverse changes during the process,'' the report has warned.

It may also cause the migration of elephant herds, the biggest attraction of Thekkady which is a major tourist centre of the State. ``The grasslands and marshy beds along the lakeshore and the marshy `vayals' are the ideal habitats for the herbivorous animals,'' the report said.

The Periyar Tiger Reserve is contiguous with neighbouring forests of Ranni and Kottayam forest divisions of Kerala and Theni, Srivilliputur and Thirunelveli forest divisions of Tamil Nadu. This area is an Elephant Reserve under the Project Elephant. The Tiger Reserve is part of the Elephant Reserve No. 10. Although elephants are widely distributed in the Tiger Reserve, the sightings are `frequent and highest' in the areas around the lake.

Intense utilisation of the area by the elephants - as well as by other large herbivorous animals - is due to the availability in abundance of palatable food in the grassland on the lake fringe and in the `vayals' close to the lake. The elephants would be left with no option but to move out when their habitats are submerged.