|June 1, 2016 at 10:53 am #6560|
A mass mortality of fish in Carambolim lake is raising a stink and along with it the suspicion that the health of the world famous birding spot may be deteriorating. Of recent a few threats have been putting the water body under stress.
Fish started dying in large numbers in the freshwater wetland some days back, after its sluice gate was traditionally opened in summer. The water is stored and released for a rabbi crop. But now it is allowed to flow waste as fields lie fallow, sources said.
Many species of fresh and brackish water fish, such as pearl spots, katla and other local varieties can be seen floating on the lake. The dead fish has attracted a large number of birds, especially raptors that fly overhead or perch themselves on dried up patches. Local residents and passers by stop to look at the dead fish and move on quietly.
“The fish started dying a few days back. It might be due to the intense heat now,” a villager said.
But a large area of the man made storage facility that covers 70 hectares is still under shallow water. The water level has fallen sharply, and tidal flow from a nullah linked to one of the Cumbarjua tributaries sweeps in at high tide.
“It is saline water that enters the lake through the nullah and with it some pollutants may also be entering it,” a local resident Chetan Kavlekar said.
The state’s only important bird and biodiversity area (IBA) outside wildlife sanctuaries is linked to the nullah on its south western side that partly circles the village on its boundary. “It’s banks have become a dumping ground of garbage, sewage and other wastes for residents,” a villager lamented.
Agreed associate professor in botany at a Ponda-based college Sima Kamat. “The fish could be dying due to influx of sewage in the lake. It raises the biological oxygen demand as lot of organic substances in the water consume the available oxygen, leaving the fish gasping for it,” she said.
The presence of nitrogen, phosphorus along with other nutrients from the influx of sewage and other pollutants boosts excessive growth of aquatic weeds. “These obstruct circulation of water and dissolution of atmospheric oxygen in the water, which the fish need,” Kamat said.
Many villagers have raised a concern in the past about the unhygienic and toxic waste flowing into it, but no remedial action has been initiated by the local self governing body or the government, sources said.
“We are are worried about the threat to the IBA from various factors. Fish mortality is not a good sign and it is an indicator that something is wrong with the lake,” president of Goa bird conservation network (GBCN) Parag Rangnekar said.
Carambolim earned an IBA status for its rich avifaunal diversity, as thousands of ducks, other migratory and even resident avifauna could be spotted here. But the waning numbers have raised doubts about the health of the water body. “Now the fish mortality is another indication,” Rangnekar said.
Birders and some villagers are aware about the impending danger of the uncontrolled pollution around the lake. “The government should initiate measures to provide basic amenities to the people,” a villager said.