State government’s Casuarina plantation scheme on India’s east coast is affecting the sand dune ecosystems. The Olive Ridley turtles are just one of the species at risk. M Vikram Reddy, faculty at the Pondicherry University, talks to Sumana Narayanan about his student’s study on skinks
On the study
Skinks are small lizards with two species found on the east coast. Eutropis bibronii, the sand skink, is more common. For the study the entire area was divided into grids with each having an area of 2,500 sq m. The target individuals were counted in each grid. The number of skink sightings was noted several times a week each year, starting from 2006. Data was collected during the day when the cold-blooded animals come out to bask in the sun.
On the initial number of skinks
In 2006, we found 21 individuals per 15 grids on the beach along the village of Vadannemeli in the Tamil Nadu coast. This was before the forest department planted Casuarina trees extensively along this area under a World Bank funded project in 2007. The idea was to create a bioshield to reduce impact of hazards like tsunamis.
On the impact of Casuarina plantations
The number of skinks sighted came down considerably after the Casuarina trees were planted—from 21 to 9 per ha. This was likely due to the Casuarina providing shade that prevented the skinks from basking in the sun. The government in 2008 removed the trees because of constant lobbying by turtle conservationists; the skink numbers, thereafter, increased to 16 per ha. The variation in skink numbers probably means that they had to move further where open basking areas were available. We do not know if the reduction in number was because they died. We did not see signs of mortality. Besides, we could not have accounted for the deaths because of predators around.
On whether Casuarina trees should be planted
They should not be planted so close to the high tide line; they are not part of the sand dune ecosystem and as we now know, they affect the ecosystem adversely.