Microplastics detected in Kaptai Lake fish 

RANGAMATI, Nov 4: Microplastics have been detected in all five species of small indigenous fish sampled from Kaptai Lake, with bottom-dwelling Tangra showing the highest level of contamination, highlighting the growing threat of plastic pollution to the lake’s aquatic ecosystem and potential risks to human health.

A study by researchers from Chattogram Veterinary and Animal Sciences University (CVASU) found that plastic particles were present in every species examined, indicating that contamination has spread across different levels of the lake’s aquatic food chain.

Published in the international scientific journal Discover Environment, the study was conducted by a team of teachers and students from CVASU’s Department of Fisheries Resource Management.

The researchers collected 75 fish samples of five indigenous species-Kachki, Chapila, Tangra, Mola and Dhela-from Rangamati Reserve Bazar, Subalong Bazar and the BFDC Fish Landing Centre.

The analysis found an average of 0.63 microplastic particles per gram in Tangra, a bottom-feeding fish that forages in mud and sand on the lakebed. Microplastics are plastic particles smaller than five millimetres.

Of the particles identified, 85 per cent were fibres and 15 per cent fragments. Polyethylene accounted for 71 per cent, followed by polyester at 14 per cent and ethylene-propylene copolymers at 15 per cent. Blue, black and white were the most common colours.

Researchers linked the contamination to household waste, discarded plastic products, tourism and abandoned fishing gear. 

Plastic bottles, packaging and other waste dumped around markets, settlements and tourist spots are carried into the lake through drains and rainwater, eventually breaking down into microscopic particles through exposure to sunlight and environmental conditions.

The study also found a significant relationship between fish size and microplastic accumulation, with smaller-bodied fish more susceptible to contamination.

POTENTIAL RISKS TO HUMAN HEALTH
The findings have raised concerns about possible human exposure through the food chain. Small indigenous fish from Kaptai Lake are often eaten whole or with minimal removal of internal organs, potentially increasing exposure to microplastics accumulated in their bodies.

Researchers cautioned that prolonged exposure could pose ecological and potential human health risks, although further studies are needed to establish the long-term effects on people.

Saifuddin Rana, an associate professor in CVASU’s Department of Fisheries Resource Management and a member of the research team, said larger plastic items gradually break down into smaller particles, which fish ingest as food.

"As a result, microplastics can be detected in different parts of their bodies," he said.

He stressed the need to control plastic use at tourist destinations around Kaptai Lake and raise awareness among tourists and local residents.