Salinity cries fowl for Ganges dolphins

High salinity in and around the waters in Sunderbans has a devastating impact on the Ganges River Dolphins, which is already endangered.  A new survey has revealed that the dolphins that once frequented the waters of Sunderbans could rarely be seen. 


The new survey that has been published in the ‘Journal of Threatened Taxa’, says that the fresh water dolphins had been decreasing in numbers as flow of fresh water into the Sunderbans has decreased. 
The survey that covered 100 km of water bodies in the delta has reported that the river dolphin was no longer seen in eastern and central parts of Sunderbans. It was now only sighted in the western parts where the salinity was comparatively lower than the other regions.


Sangita Mitra and Mahua Roy Chowdhury has authored the paper (survey) named  “Possible Range Decline of Ganges River Dolphin Platanista Gangetica in Indian Sundarban”, that has been published in the journal , that has thrown light on the endangered mammal. 


The study sheds light on how the climate change and human interventions has made life miserable for the mammals that once used to thrive in large numbers in the rivers around the estuary. Fresh water is crucial to the dolphins and these mammals cannot stay under waters for a long time because of the salinity. It has also been reported that the increase in sea level has also led to an increase in salinity in the channels and rivers around the Sunderbans. 


The report also notes that large barrages upstream and diversion of fresh water has all added to an increase in the salinity levels in the waters around Sunderbans. 


In the Sunderban area, four of the 40 species of Dolphins are found. The dolphins found here are fresh water ones and never enter the sea. Among the fresh water dolphins on the world, those found in the Sunderbans are said to be one of the remaining species. 


The authors say that they have not yet completed the survey and more has to be done in this regard. Meanwhile, environmentalists and nature lovers are a worried lot and point out that if timely intervention is not made, it was only a matter of years that the last dolphin also disappears from Sunderbans.

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