CHENNAI: The introduction of spotted deer and bullfrogs from mainland India to the Andaman and Nicobar Islands is posing a threat to native island species, according to a report by the National Biodiversity Authority (NBA).
The report states that the spotted deer, also known as chital, has been identified as a potential threat to the native floral and faunal diversity of the Andamans as it eats up the forest cover.
Researchers identified that changes in the vegetation cover negatively influence abiotic factors such as temperature, moisture and light intensity, besides having an unwanted impact on beneficial soil-dwelling organisms such as microbes, insects and other smaller invertebrates and vertebrates, thereby cascading its adverse impacts on the natural food web.
Dr Sandilyan, former fellow on Invasive Alien Species, Centre for Biodiversity Policy and Law (CEBPOL), NBA, Chennai, told Express that researchers have found that forest ground degradation had an impact on the native lizard population of the Andamans.
Similarly, it was found that the survival of subterranean egg-laying agamid lizards such as coryphophylax species and skinks was affected due to changes in the vegetation cover.
It was also found that the Indian bullfrog, which was introduced into the Andaman group of islands, is threatening native species of frogs.
"These bullfrogs managed to escape into the wild and continually expand their territory. This species is a prolific breeder with a short breeding season and produces a clutch containing more than 5000 eggs. Recent studies established the carnivorous behaviour of the tadpole and how it affects tadpoles of native species," says Sandilyan, who is the lead author of the book Impacts of Invasive Species on Island Ecosystems of India with Special Reference to Andaman Group of Islands.
Sandilyan rues that a number of invasive species have been identified in the Andaman group of islands. However, there are no detailed long-term studies and very poor qualitative and quantitative studies, he says.
Stressing the need to strengthen quarantine regulations to screen the entry of invasive species into the Andamans, Sandilyan says the government should take the initiative to set up a regional invasive species research and management cell to protect native species from becoming extinct.