Litter ferries invaders from afar to Tamil Nadu coast
The study recommends monitoring biological invasions in coastal waters near urban areas due to the high number of pressures, including intense vessel traffic and abundant marine litter introduction.
Samples collected from TN and Pondy coasts with alien species.
CHENNAI: Buoying marine litter can increase the risk of invasion of alien species through to long-distance dispersal of marine species, a new study along the coasts of Tamil Nadu has found.
While previous studies have quantified the impact of plastic litter (mainly ingestion and entanglement) on marine wildlife in Indian waters, this is the first documentation of marine litter acting as a vector for species dispersal here.
According to the study by Gunasekaran Kannan of Sathyabama Institute of Science and Technology and other researchers, published in the Marine Pollution Bulletin, 17 species were identified on 367 fouled litter items (marine debris samples).
Among them was mytella strigata (charru mussels or the dreaded kakka aazhi in local parlance), a native of South American coasts that has overrun the local ecosystem in Ennore and Pulicat wetlands, and Vembanad backwaters in Kerala.
As part of the study, the researchers collected marine litter samples washed ashore in Puducherry, Silver Beach, Samiyarpettai and Pudhupettai, Veerampattinam, Chinna Veerampattinam, Periyakuppam and Parangipettai beaches.
“Remarkably, we found the non-indigenous mussel mytella strigata attached in high-density groups to fishing nets. This species, previously documented in India in 2019 on floating plastic bottles, wooden pilings, hulls of boats, and walls of fish cages is considered invasive. Marine litter may thus have facilitated its spread in Indian waters,” the report said.
The findings indicate that the growing presence of plastic litter may increase the probability of introducing non-indigenous and invasive species into Indian waters, potentially generating a negative impact on the ecological characteristics of the invaded habitat.
It has been estimated that 4.8–12.7 million tonnes of marine litter enter marine habitats annually. Nearly 19 to 23 million tonnes of marine debris produced worldwide in 2016 entered aquatic habitats. Once debris enters the sea, it either floats or sinks, and can be transported to other areas by currents, washing up onto the shoreline and beaches or drifting offshore and sinking to the deepest part of the ocean.
The study recommends monitoring biological invasions in coastal waters near urban areas due to the high number of pressures, including intense vessel traffic and abundant marine litter introduction.
“Implementing monitoring programmes becomes crucial to understand the extent of the interaction between marine litter and fouling organisms (organisms that attach with litters), as well as to assess the role of marine litter in introducing non-indigenous and invasive species,” it added.
