11th Aug 2018 THE HINDU Editorial Analysis ha ii
The Andamans new colonisers o The voracious animal gulps down anything that would fit in its jaws: centipedes, leeches, native frogs, lizards, small snakes, and even chicks and ducklings, which are an important source of food for the islanders o The bullfrog, found widely in mainland India and protected under Schedule IV of the Indian Wildlife Act 1972, is making the most of a free run that it's enjoying in Andaman . In the Andaman Islands, it can rain eight months of the year. The first rains in May are the signal for the bullfrogs to come out of the streams and agricultural ponds that have become their shelters. They breed by the hundreds, with each female able to lay between 3,500 and 20,000 eggs
o Not all survive, but enough live to breed again, ensuring that the horde extends their range. With an average life span of seven years, and time to sexual maturity of 10-12 months, their population can dramatically shoot up in a very short time, which is precisely what happened once they landed in the islands So far, the bullfrog has been found in six out of the eight major inhabited islands. In 2017, it was even found in Little Andaman, which is separated from the Greater Andaman Islands by more than 55 km of sea. "This kind of incursion into remote islands is not naturally possible in such a short time," says a doctoral student at the Centre for Invasion Biology at Stellenbosch University (South Africa) . The frog has acquired many names in the course of its journey through multi-cultural settlements of the island: shona beng ('Golden frog', for the..
prominent golden stripe) among the Bengali settlers; haramendak ('Green frog', for its olive-green skin) in Ranchi villages, where you could hear Oraon, Sadri or Munda being spoken; and dey-phala ('Green frog") in villages where the 2,500-odd Karen community stays Whatever the name or language, the narrative of economic loss and ecological threat is a constant o As early as 2001, the bullfrog had already established breeding populations in one village. By 2009, it had spread to seven villages. Since then, at least 53 villages have reported the bullfrog in worrying densities Like most contemporary tales in the archipelago, the bullfrog story may also have to do with the earthquake and the tsunami that devastated large parts of Andaman and Nicobar islands in 2004. Following the decline of
....natural fish stock, the local administration encouraged integrated farming, with aquaculture in agricultural ponds o There are now over 2,500 such ponds in the islands, most of them filled with stocks of exotic, fast-growing fish imported from the mainland.The fishling stocks (mostly from Kolkata) released into some of these ponds were contaminated with bullfrog eggs and tadpoles. All fingers point at the local fisheries department, which has, however, dismissed these claims and accused private traders . The tsunami had created salty channels in the area and rendered large tracts infertile. So, many had turned to creating agricultural ponds-to rear tish and also because they would serve as sources of freshwater when the rains filled it up
Bullfrogs are found all over mainland India, but it is in the unique ecosystem of the islands that it becomes a major threat. Unlike the mainland, resources on the islands are scarce for big animals, while natural calamities are more frequent. The wildlife here has evolved in a miniature setting: there are no large herbivores (the largest is the Andaman wild pig) or large carnivores "Islands have fewer species, but their nature make them irreplaceable. They are found no where else in the world... This makes the entire food web in the islands very different from that of the mainland," says a senior principal scientist at the Centre for Cellular and Molecular Biology Hyderabad The Zoological Survey of India has found that out of the 9,130 marine and terrestrial species discovered so far in the islands, 1,032 species (or
11.30%) are endemic (found only in the Andamans). In the constraints of land, this endemicity increases to nearly 25%, or 816 out of the 3,271 land species But the bullfrog is only the latest entrant in the Andamans' 150-year-old history of invasives, with alien species introduced in waves by the British, the island territory. These include the elephant(introduced for logging and later abandoned), chital, hog deer, and barking deer (all three for game meat) Invasives have come in all forms to the Andamans. The Japanese introduced the Giant African Snail, one of the 100 worst invasive species as described by the International Union for Conservation of Nature (IUCN), in the 1940s during their three-year occupation. It has now established itself...
...as a major agricultural pest Meanwhile, about 90% of the fish being bred in ponds are carps and other exotic fish which have even established natural breeding sites outside human-created ponds. Similarly, the islands are home to at least 592 introduced alien plant species, some indirectly pushing endemic plants to the fringe o "Adult bullfrogs pose a threat to small endemic vertebrates (from frogs to birds). Within frog species, it can have a two-pronged impact on the Limnonectes genus of frogs. Bullfrogs not only eat the native frogs, even their diets overlap, indicating a possibility of competition," said the doctoral student at the Centre for Invasion Biology at Stellenbosch University (South Africa)
It isn't just their size that works to their advantage. It's their appetite for meat, even at the tadpole stage. Bullfrog tadpoles are highly carnivorous, preying on other tadpoles (even native tadpoles) heavily Globally, invasive species, particularly in islands, are becoming the focus of numerous organisations. The Convention on Biological Diversity has said that invasives have contributed to 40% of all animal extinctions since the 17th century The IUCN has formulated guidelines for managing invasives specifically in islands, largely involving data collection, community engagement, policy measures and management plans
Hi . Im an UPSC personal coach with 4 years experience . I love studying and teaching .I'm a public speaker , engineer ,media person