Sundarbans’ Saline Killer
I read this very interesting article on Sunderbans in TOI. It explains the reason behind the increasing man-animal conflict. How the water is getting more saline, causing the animals and the vegetation to move north wards.
Sundarbans’ Saline Killer
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.
Link - http://timesofindia.indiatimes.com/H...ow/6012927.cms
Uneven prey base behind straying: Officials
Read this news about Sunderban.
Uneven prey base behind straying: Officials
KOLKATA: In 2001, tiger straying in the Sunderbans broke all records with 26 incidents. In 2010, less than half a year gone by, the number has crossed the 26 mark. Last month, as many as five tigers raided several villages over just two days. The trigger, apparently, is Cyclone Aila.
Uneven distribution of prey base and depletion of the vegetation favoured by tigers are the biggest reasons behind straying in the Sunderbans, say experts. "Post-Aila disturbance is a crucial factor," the state's chief wild life warden S B Mondal said.
Analysis of recent radio-collar inputs says that the prey base has not dwindled. It is the uneven distribution that is leading tigers to drift in search of prey, say forest officials. The study, carried out Sundarbans Biosphere Reserve (SBR), also shows a steady decline in the tiger's favourite vegetation, the vanishing mangrove species of Hetal (phoenix paludosa).
On an average, 12 to 18 tigers stray in a year in the Sunderbans. "We first weed out the common factors a tiger strays if it is old and cannot hunt, if it's the mating season when the big cats look for easy prey, or of it's a tigress with cubs," said SBR director P K Vyas.
No other tiger habitat in the world, says Vyas, is impenetrable by cattle like cow and goat. In the Sunderbans, the only prey available to tiger are deer and wild boar. "There is no absence of prey, but there certainly is an imbalance in the distribution of prey base in the tiger-islands. In Dobanki, we got deer five years ago. The third generation deer were released in the forest after being completely acclimatised with the food and ecology of the mangroves. Since our first experience was a success, we want to replicate it on other islands too," said Vyas.
Senior forest officials suggest radical changes, like restricting tourism or shifting tourism hubs on the basis of new tiger zones. Animesh Sinha of Sundarbans Environment and Eco Development Society (SEEDS), who has been working in the islands for a long time, vouched that there has been a steady increase in the tiger population. "With this growth, each tiger now has a smaller territory. So straying is on the rise."
Wildlife expert Pranabesh Sanyal said: "Rivers and creeks in the sea facing islands have witnessed an alarming rise of salinity, specially after Aila. This is forcing tigers into the southern core area, with declining prey density in the northern zone."
Botanical Survey of India (BSI) officials feel global warming and increasing salinity of Sunderbans rivers is triggering a major change in the habitat vegetation of the mangroves. "We have studied the phenomenon. Now we will have an in-depth study how the vegetation is undergoing rapid changes in the Sunderbans, one of the most sensitive biodiversity zones in the world," said Dr H K Debnath, principal investigator of Lead Institute of BSI.
Link - http://timesofindia.indiatimes.com/c...ow/6030110.cms
