THOOTHUKUDI: The invasive mutti chippy (Mytella strigata) -- a mussel variety native to the Pacific coasts -- has been spotted along the Punnakayal seashore in Thoothukudi.
Experts in marine biology suggested that deballasting -- removal of ballast water loaded into ship tanks for stability -- could have been the primary factor in the introduction of the species, which could pose a threat to indigenous marine life. They called for urgent measures to control the spread of the invasive species into the Gulf of Mannar marine biosphere, which is a unique and ecologically important marine ecosystem.
The fishermen in Punnakayal -- largely unaware of the invasive nature of the species -- told TNIE that they have been spotting the mutti chippy over the last two to three years along the estuarine waters where the distributaries of Thamirabarani river meet the Gulf of Mannar. "The mutti chippy is found clinging onto the hull of boats, fishing nets, wooden poles, boat jetty structures, and on any immovable materials abandoned in the shore," said Virgin, a resident of Punnakayal.
The officials of ICAR-National Bureau of Fish Genetic Resources said that Mytella strigata, an invasive species belonging to the Pacific coast of Central and South America, could potentially cause ecological damage by occupying the spaces of native mussels and oysters. Rapid colonisation of the species in the coastal mangrove forests and associated wetlands of Thoothukudi could reduce the population of shrimps and crabs, said experts.
A research paper titled "Invasive surge: swift feast of bellicose alien mussel, Mytella strigata in Indian mangroves", published in February, reported the presence of M strigata in Vellar estuary and Pichavaram mangroves, and attributed its invasiveness to its tolerance to high salinity, rapid growth rate, early maturation, and high reproductive capacity. The study said that M strigata had primarily entered Indian waters via ballast water discharge.
Dr T T Ajith Kumar, Head (regional centre, Kochi), ICAR-National Bureau of Fish Genetic Resources, said that M strigata can potentially displace indigenous species such as Perna viridis (green mussel), Perna indica (brown mussel) -- consumed in southern districts. It was first spotted in the Kochi backwaters. "Deballasting must be inspected keenly, as it inadvertently facilitates the introduction of non-native organisms into local waters," he said, adding that they are studying the impact of the species.
ICAR principal scientist Dr Divya -- one of the authors of the study -- told TNIE that the M strigata showed higher bioaccumulation of heavy metals during studies, and it acts as a sentinel species for detecting heavy metals in an aquatic environment.