A recent study has confirmed that the Vembanad backwaters, Kerala’s largest wetland ecosystem, is undergoing rapid ecological decay due to a range of reasons including unauthorised construction activities, violation of coastal regulation zone (CRZ) norms, intense pollution and heightened tourism activities.
Though the Vembanad backwaters has been under glaring spotlight over the last few years for its deteriorating ecological balance, the new findings are alarming and call for speedy government action.
The study, undertaken by the Department of Marine Biology, Microbiology and Biochemistry at Cochin University of Science and Technology (CUSAT), conducted a detailed analysis of heavy metals in water samples, sediment samples, organisms, analysis of pesticide, physical and chemical characteristics of the backwater. It was conducted during the pre-monsoon months of February and April and monsoon months of June and August in 2017 for the Kerala State Pollution Control Board.
One of the striking findings of the study is that there has been a concentration of heavy metals like zinc, nickel and copper in aquatic organisms, lending a major threat to the ecosystem. The marked decline in the clam fishery in the estuary is a case in point.
There has also been the presence of emerging pollutants such as benzyl benzoate, benzene propanoic acid, cyclic octaatomicsulphur which have application in pharmaceuticals as preservative, fungicide and insecticide in the treatment of skin diseases and cosmetic products like perfumes and bath gels.
The study also cites the effect of the unscientific construction of the Thaneermukkom barrage in 1975 on the coastal ecosystem. The barrage may have been built to prevent saline water intrusion from the sea, but it has resulted in gross changes in the physical, chemical and biological entity of the wetland system.
“Unrestricted human interventions like the Thanneermukkom barrage and Thottappilly spillway along with other anthropogenic impacts have created irrevocable consequences on the environmental entity of this Ramsar site, altering its production potential,” the study headed by Dr S Bijoy Nandan, head of the department at CUSAT finds.
The study also calls for strict adherence to CRZ norms and a complete stop to unauthorised construction activities on the backwaters. Declared a Ramsar site in August, 2002, the study report notes that there has been no serious intervention by either the Centre or the state government to improve the use of the wetland. There is also a need to restrict tourist activity on the wetlands especially the use of houseboats which have been a major cause of water pollution.
“A carrying capacity based model needs to be developed on the impact of tourism and related pressures in the wetland,” the report underlines.
Over a million people depend on the Vembanad ecosystem in Kerala and widespread land reclamations have resulted in a drastic reduction in its size.