Sundarban's Saline Killer

http://timesofindia.indiatimes.com/home/environment/flora-fauna/Sundarbans-Saline-Killer/articleshow/6012927.cms


Ashutosh Dali could not grow a single shoot in his field ever since it got flooded by saline water during last year’s Cyclone Aila. Yet, the 50-year-old fisherman will not go fishing any more. Not after what happened to him that winter morning three years ago. “Now, everytime I look at the forest, I see those blood-thirsty fangs. The terrifying growl still rings in my ears,” says Ashutosh, pointing to a deep gash on his left thigh. A botched attempt at tranquilizing a tiger had left two others wounded that morning. So, while his neighbours go fishing, Ashutosh — once a deft fisherman — keeps himself busy with his barren paddy field.

Between the World Environment Days of 2009 and 2010, no less than 25 tigers strayed into Sunderbans villages and left around a dozen people injured. Never before in recorded history has this tide country seen so many tigers venturing beyond the forest limits. The forest department has been reluctant to admit it, but wildlife experts believe this unique habitat of the Royal Bengal Tiger is undergoing a change and there are enough indications to suggest that the terrain is turning increasingly hostile for the big cat. Several other species of flora and fauna are battling for survival as well in the world’s largest mangrove forest.

Rise in water level and increasing salinity in the rivers and creeks pose the biggest threat to the Sunderbans, according to experts. It has set off a chain of ecological mutations that has resulted in the flight of tigers from the southern end of the forest to the northern part, which is hemmed by human habitation. Frequent straying has been the inevitable result.

And its not just tigers that have been affected. Several species of dolphins and fishes, too, have either moved northward or gone extinct, claim scientists. Trees like sundari and passur and phundun have shifted from the outer estuary to the mid-estuary region, an indicator that saline water has penetrated deeper into the forest.

“It is clear that the Sunderbans is a victim of accelerated sea-level rise. Salt wedges from the sea have been extending inwards into the rivers and creeks as the water swells. This can be linked directly to the movement of tigers northward, leading to a higher density of big cats in the area and consequently more straying,” explained Pranabesh Sanyal, former director of Sunderban Tiger Reserve.

Said Tuhin Ghosh, senior lecturer of Jadavpur University’s School of Oceanographic Studies: “The increasing salinity upstream is changing the mangrove zonation. The trees and plants common in the southern Sunderbans can now be seen in the northern part as well. And some trees in the northern regions, which can’t stand too much salinity, are dying. This is changing the character of the forest and food availability for animals and some animals are migrating northward, some are adapting to the changed situation and some are getting extinct gradually.”

Salinity has gone up by 20% in the Sunderbans since 1990. Water level too has been rising by 3.14 mm on an average every year at Sagar Island while at Pakhiralay, the rate has been 5 mm/year. Sighting records confirm the scientists claims. According to Dinesh Mondal, a fisherman of Bali island, “It seems too many tigers are prowling around the villages of this region nowadays.” Dinesh is right. While more tigers would be seen in the southern areas of Haldibari and Mechua a decade back, most sightings now happen around Sudhanyakhali and Netidhiopani in the north. “This suggests that tigers have been migrating. But many of the prey animals haven’t, for they can withstand salinity better. So, we have an uneven concentration of tigers,” said Bittu Sehgal, wildlife activist. Further confirmation of salinity rise comes from the proliferation in the number of Irrawaddy dolphins in the northern creeks while the Gangetic dolphins that can’t survive in saline water have almost disappeared.

Also, cyclones and low-pressure disturbances have been moving north along the coast, veering closer to the Indian Sunderbans, instead of moving away towards Bangladesh as earlier. “A rough sea means more saline water and higher waves that could spell doom for the Sunderbans unless we have a proper mangrove barrier,” said Gautam Sen, oceanographer. According to a study, there has been a 20% reduction in mangrove cover since 1969, added Sen.

At least two islands of the Sunderbans have disappeared over the last three decades. Apart from the apparent sea level rise, the neo-tectonic movement in the region and other geomorphological reasons are active behind this phenomenon. It’s a dynamic process and new islands have been emerging as well, to compensate for the loss, argue scientists.

Then there are the anthropomorphic reasons. Of the 100-odd islands, 54 have no forest cover left, thanks to human colonization. People started settling on these islands around 250 years ago, when siltation was not yet complete and the islands were yet to be mature. The early settlers constructed embankments around the islands — altogether 3,500km — permanently affecting the natural balance of the region, according to social activist and Sunderbans expert Tushar Kanjilal.

The key to saving the Sunderbans is the preservation and plantation of mangroves. This will check salinity and prevent displacement of tigers, thereby bringing down the man-animal conflict. Fishing must be restricted and mangroves protected to give the Sunderbans a fresh lease of life.