Invasive mussel species in Ennore can wipe out prawns, clams, claims study by Tamil Nadu fishermen

CHENNAI: An invasive South American mussel species is spreading through the Ennore creek area due to the unchecked release of ballast waters from ships and threatens to wipe out the commercially important prawn species, says a study by fishermen of the area, who have written to the State Wetland Authority and fisheries department requesting urgent intervention to stop the spread.
The fishermen, who conducted the study with scientists and environmentalists, have also written a paper on the subject and plan to publish it in a journal.
The mussel species Mytella strigata (Charru mussels) would spread like a carpet over the river bottom preventing prawns from grazing or burying themselves in the river sediment, says the study, adding that it is slowly wiping out locally prevalent yellow clams (manja matti) and green mussels (pachai aazhi).
S Kumaresan, a fisherman who is one of the authors of the study, said the infestation had already spread to 11 out of 52 fishing sites. It ws first noticed when road and conveyor bridges were built 15-20 years ago.
"We noticed small patches of these mussels stuck to bridge columns and unremoved debris after Cyclone Vardah in 2016. Now, they have spread far north towards the Pulicat waters. The ash-covered river-bottom is also helping this expansion."
The mussels also suck in hundreds of litres of water daily resulting in a water column that is clear instead of muddy. Clear water is bad for fishing as fish can see the nets and avoid them.
Nithyanand Jayaraman, a volunteer with the Save Ennore Creek Campaign and co-author of the study said, "The only explanation is the failure of Indian regulators and the port authorities to stringently enforce ballast water regulations on ships coming to Kattupalli."
This is first ever record of the invasive species on India's east coast, said Naveen Namboothri, a marine biologist with Dakshin Foundation.