Wildlife & Biodiversity

Microplastics in 90% frogs studied in Bangladesh delta, can threaten biodiversity: Study

Microplastics abundance in frog samples from Bengal delta much higher than that observed in Europe, China in past studies

By Madhumita Paul
Published: Tuesday 04 July 2023
Toxic chemicals in microplastics cause severe damage and even mortality. Photo: iStock

Microplastics in frogs are potential threats to healthy wetland ecosystems and the problem was found to be acute in Bangladesh, according to a new study. 

As much as 90 per cent of the frogs sampled from the Bengal delta in Bangladesh had microplastics, the report published in the journal Environmental Advances noted.

Frogs play a vital role in the food web and help in keeping aquatic ecosystems healthy. They also control insects that cause various diseases in humans like mosquitoes of malaria and dengue.

Toxic chemicals in microplastics cause severe damage and even mortality, according to the authors of the report. 

Personal care products, cosmetics, textile fibres and air blasting media are the primary sources of microplastics in aquatic environments. The secondary sources are tiny plastics that originate over time from larger plastics by chemical and photochemical reactions.

Bangladesh is home to 47 species of frogs, of which nine are threatened and six near-threatened, according to the International Union for Conservation of Nature, the global wildlife conservation authority.

In this study, 27 frogs from nine different species were collected from different habitats of the Bengal delta to observe the microplastic’s abundance and were compared based on their habitat, length and body weight. 

Frog samples were collected from the lakes of Jahangirnagar University located in Savar, Bangladesh in April 2022.

This study is the first of its kind in the country. Until now, very limited work has been done on the investigation of microplastics in frogs and most of them were in tadpoles.

Another study reported microplastics in the European Common Frog (Rana temporaria) collected from a high-mountain ecosystem (the Cottian Alps in northwest Italy). 

Microplastics were also found in tadpoles of pond-breeding amphibians from Poland and Central Europe and in Yangtze River Delta, China. 

Compared to these studies, microplastics abundance in the frogs of Bengal delta was very high.

Some observations from the study:

  • The abundance of microplastics was highest in the Asian Common Toad (Duttaphrynus melanostictus). Microscopic analysis through a stereo microscope showed that common microplastic particles are fibre-like (84 per cent) and most of the microplastics are colorless
  • The gastrointestinal tract of 27 frogs yielded a total of 195 microplastics particles
  • Not only microplastics, but few mesoplastics (larger than 5 millimetres in size) were also found in the frogs. Out of all the plastics found in the frogs, 96 per cent were microplastics and the rest were mesoplastics.
  • No significant correlation was found between the presence of microplastics with the frog’s body length and weight. This indicates that microplastics abundance in an organism’s body depends on the number of microplastics present in the environment to which the organisms are exposed.

Frog population is gradually declining due to environmental degradation, accumulation of toxicants and various diseases and other abnormalities caused by microplastics, the researchers noted.

They called for planned actions to conserve frog populations to protect the environment and ensure a safe food supply.

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