Scientists point to danger of particles travelling up the food chain when small ocean-floor dwellers are eaten by fish

Microplastics are practically everywhere, according to latest research. Now, scientists have recorded these tiny plastic particles—less than one millimetre in length—closer home, in the marine life off the Kochi coast. Invertebrates dwelling on the ocean floor as well as fish now house microplastics.

Fluorescent fibres

Earlier this year, scientists at the Integrated Coastal and Marine Area Management Project Directorate at Chennai’s National Institute of Ocean Technology recorded fluorescent blue and green microplastic particles and fibres in two species of marine worms Sternaspis scutata and Magelona cinta and in a species of bivalve (a clam-like, soft-bodied animal that lives in shells) named Tellin a that were fished off the Kochi coast.

The team examined the fibres using an extremely powerful microscope and confirmed it to be Polystyrene, one of the most widely used plastics. Incidentally, it is also the most commonly seen microplastic litter in marine habitats.

According to scientists, microplastics can easily travel up the food chain when small ocean-floor dwellers are eaten by larger marine predatory fauna such as fish.

A team from the Central Marine Fisheries Research Institute (CMFRI) in the city had already recorded microplastics in the stomach of anchovies ( Natholi ) from the mud banks of Punnapara in the neighbouring Alappuzha district four years ago.

“We have also recorded microplastics in sardines [ Mathi ] off the Kochi coast,” said Dr. V. Kripa, principal scientist and head of the Fishery Environment Management Division at CMFRI.

Microplastics are an issue because once inside the bodies of marine life forms, they can cause internal lesions.

However, there have been no regional studies on whether these particles have moved through the food chain into bigger animals, she added.

Apart from accumulating toxins, microplastics can threaten microfauna such as plankton (tiny, single-celled creatures that fish and even whales feed on) that thrive in oceans, according to Dr. Kripa. However, since microplastics are small enough to come out through the digestive tracts of most larger lifeforms, they might not cause the kind of direct damage that larger pieces of ingested plastics (or macroplastics) could create, Dr. Kripa said. There have been instances of larger marine animals, including sharks and whales, washing up on beaches with their stomachs filled with plastic.

Yet, research shows that microplastics may not be that benign. Last year, a research team from Mahatma Gandhi University discovered microplastics in all the 10 samples of sediments taken from the bottom of the Vembanad Lake which spans across the districts of Ernakulam, Kottayam, and Alappuzha.

Clams, which thrive in the lake, are eaten by people. A few months ago, a study by researchers at Mumbai’s Indian Institute of Technology found that most major brands of salt in the Indian market today were contaminated by microplastics.