CHENNAI: The Ennore-Pulicat wetland complex, which is ecologically sensitive and attracts thousands of migratory birds annually, is losing its biodiversity due to extensive spread of invasive Charru mussels, the same species that wreaked havoc in Kerala’s Ashtamudi Lake, a Ramsar site, in Kollam district.
Despite such a crisis brewing, the Tamil Nadu government is buying more time and has initiated no removal work so far.
In the last one year, repeatedly, the southern bench of the National Green Tribunal (NGT) had directed the government to come up with a solution and start removing the invasive mussels but no concrete step was taken. On Monday, the government once again delayed removal and informed the tribunal that it would commence the works after northeast monsoon in January.
The theory that the government put forth citing scientists of Dr MGR Fisheries College and Research Institute is that freshwater influx would kill the Charru mussels during the monsoon so that it could spend only less money for the removal after rains.
This has irked the bench, comprising Justice Pushpa Sathyanarayana and expert member K Satyagopal, who demanded scientific evidence to back its theory.
Satyagopal said during the southwest monsoon this year, Chennai, Tiruvallur, Kancheepuram and Chengalpattu districts received above normal rains. If freshwater can kill these mussels, then it should have been controlled, he said.
“Did you assess the density of Charru mussels before and after monsoon? If you can provide the data, then we can believe. Kerala receives more rains than Tamil Nadu, then why Charru mussels couldn’t be controlled there,” he questioned the government counsel.
As per the local fishermen, the invasive mussel became more visible in 2017, and by 2022 colonisation appeared so intense and widespread. They said the invasion affected the fishery of other edible oysters, green mussels, prawns and fish.
In the previous report, the Central Marine Fisheries Institute scientists submitted its final report to the state fisheries department that recommended, “Only option to control the population was manual or mechanical removal of this species from the affected area at frequent intervals. The mussels thus removed can be dried in an open space away from the coastal area to avoid the chances of its re-entry into the ecosystem. The dried shells may be used in the lime industry that is already in operation or for any other industrial purposes,” the report said.
Now, the problem has gone beyond Ennore wetlands, and is spreading rapidly deep inside Pulicat bird sanctuary, which is a matter of serious concern.
The Public Works Department officials have inspected the affected areas in Ennore on Saturday and Sunday. It was found the mussel growth has reached the surface area in three locations. On the question about whether ballast waters from the ships is the source of these mussels, the NGT bench asked the government to fix the accountability on the ports responsible and it would impose a penalty.