- A recent study reports the presence of microplastics in the scats of jungle cat and fishing cat in the Indian Sundarbans.
- Microplastics were detected in higher concentration in the jungle cats’ scat; fibres linked to textiles, fishing gear, and packaging made up over 70% of detected particles.
- The findings suggest direct environmental exposure and trophic transfer through contaminated prey, highlighting the need for stronger plastic management in the Sundarbans landscape.
Plastic pollution has long been visible in the mangrove ecosystem of the Sundarbans in the form of waste such as bottles, food wrappers, and discarded fishing lines and other gear. What has remained largely underexplored is the journey of microplastics (particles smaller than 5 mm) and mesoplastics (5-25 mm in size) within and across these habitats.
A study published last year in the journal Environmental Research reports the presence of microplastics in the scats of the jungle cat (Felis chaus) and fishing cat (Prionailurus viverrinus) raising concerns about plastic movement across ecosystems and trophic levels.
Researchers report the presence of microplastics and mesoplastics in the scat of these small felids from the Indian Sundarbans and adjoining coastal landscapes.
The study emerged from years of work on plastics in the region’s mangrove-estuarine systems. “We had already identified microplastics in soil, water and estuarine fish, and that led us to investigate microplastic contamination in the higher carnivores of this ecosystem,” says Shrayan Bhattacharjee, lead author of the study and a doctoral fellow at the Ramakrishna Mission Vivekananda Centenary College, Rahara, West Bengal.
The jungle cat and fishing cat are mesocarnivores (medium-sized carnivores) that primarily feed on fish, crabs, rodents, amphibians, birds, and reptiles. Despite their ecological importance, both species remain understudied, particularly in the context of effects of emerging pollutants. Bhattacharjee says, “We found that the Gangetic estuary is an overlapping habitat zone for these two important felids, and that there was a dearth of scientific work on microplastics. For fishing cats, the only comparable study was from Sri Lanka.”
A story in scat
The researchers relied on scat analysis, a non-invasive method increasingly used in dietary and monitoring studies. They collected scat samples from February to July 2023, from the western non-protected area of the Indian Sundarbans where human activity including tourism, fisheries, and unregulated waste disposal are intense. “The research was conducted in non-protected areas of the Sundarbans Biosphere Reserve, as the eastern part of the Sundarbans is strictly regulated as a tiger reserve,” the study notes.
Microplastics were detected in all scat samples; they were higher in jungle cat samples (12.6 ± 1.93 MP/g d.w) compared to fishing cat scat (10.5 ± 2.12 MP/g d.w). Slightly larger plastic fragments, or mesoplastics, were also detected, particularly in fishing cat scats, at about two to four particles per scat. Microplastic fibres dominated the findings — more in fishing cats than jungle cats — accounting for over 70% of all microplastics detected, with most being transparent, blue, or red: colours commonly associated with textiles, fishing gear, and packaging materials.
“Fibres are particularly concerning,” Bhattacharjee says. “They travel long distances in water, are easily ingested, and probably pass through prey species to the predator.”
A risk assessment of these polymer particles identified polyethylene and ethylene vinyl alcohol: polymers widely used in packaging, fishing equipment, and industrial products. Based on their chemical toxicity scores, microplastics in jungle cats got sorted under the ‘extreme danger’ category, while those in fishing cats were classified as ‘dangerous’ in the Polymer Hazard Index.
Exposure pathways and implications
The researchers suggest two main exposure pathways that are likely operating simultaneously: direct uptake from contaminated environments, and indirect ingestion through prey.
“Microplastics are now widespread in wetland water, sediments, and prey species including fish, amphibians, birds, and rodents. Ingestion through food is a major pathway, but exposure may also occur through contaminated water, inhalation of airborne particles, and plastics carrying toxic chemicals,” says Samrat Chakraborty from the Department of Zoology, University of Calcutta and IUCN Red List Assessor of Global Fishing Cat Distribution. “These pathways raise concerns about long-term health effects rather than immediate mortality.”
Bhattacharjee adds, “Microplastics reach here mainly from three different routes. First, waste carried and deposited in the estuary by upstream rivers; second, marine-transported waste; and third and most importantly, locally produced plastic waste mainly from domestic use, tourism, and fisheries activities.”
The study situates these findings within a larger context of pollution in the region. The Ganges, flowing from the Himalayas to the Bay of Bengal, acts as a massive conveyor belt for plastic waste (mostly fibres) generated upstream. The river also carries large quantities of non-biodegradable and non-mineral waste. “We termed that collectively as anthropogenic non-biodegradable waste (ANBW), and it is made up of plastic, rubber, synthetic resin, and industrial chemicals,” explains Bhattacharjee.
Concerningly, an estimated 1-3 billion microplastic pieces drain into the Bay of Bengal every day, and once in the estuary, plastics are further concentrated or transported by tides and trapped within mangrove vegetation.
These small felids depend on a prey base of rodents, amphibians, fish, and birds: species already known to ingest and accumulate microplastics in polluted landscapes.
“Unlike larger carnivores like tigers or lions, these small felids often consume prey whole, including the gastrointestinal tract where microplastics tend to accumulate. So, if the prey is already contaminated, all of that enters the felid’s body,” Bhattacharjee says. This raises concerns over trophic transfer and biomagnification: more microplastics would accumulate in animals with each successive level of the food chain, as larger predators prey upon smaller animals. Other sudies echo this, with results showing more microplastics in carnivores than herbivores.
Additionally, where the cats live may matter just as much. “The jungle cat’s broader diet and range may increase chances of encountering contaminated prey, but fishing cats, despite their more specialised diet, may be equally or more exposed because aquatic prey often contain high microplastic loads,” explains Chakraborty.
While the study did not examine tissues directly, the presence of very small microplastics raises questions about possible internal accumulation. Particles below 150 micrometres have been reported to cross intestinal barriers, causing inflammation, oxidative stress, and cellular damage.
However, while the study does raise concerns over potential biomagnification and accumulation in the Bengal tiger as an apex predator, Arunava Mukherjee, co-author and Assistant Professor at the Ramakrishna Mission Vivekananda Centenary College, Rahara, West Bengal, urges caution. “We must not panic. Chronic exposure may induce cellular toxicity, reproductive anomalies, and physiological stress, but microplastic accumulation through the gastrointestinal tract is not yet well-established in higher mammals,” he says.
Conservation and policy implications
Mesocarnivores like the fishing and jungle cats act as indicators of human-induced stressors that disrupt the habitat. “We consider the fishing cat as an indicator of wetland ecosystem health, especially for this habitat that sustains allied flora and fauna, and in turn, livelihood and living for wetland-dependent communities,” says Ajanta Dey, Joint Secretary and Programme Director of the Nature Environment and Wildlife Society (NEWS), and member of the IUCN Commission on Ecosystems Management (IUCN-CEM).
Both Bhattacharjee and Mukherjee emphasise that the findings have implications beyond jungle and fishing cats, calling for landscape-level policy responses and enforcement rather than isolated clean-ups and bans.
“Alongside habitat loss, conflict, and prey depletion, microplastics represent a form of internal exposure that conservation planning rarely considers,” adds Chakraborty.
The authors recommend declaring mangrove tourism zones plastic-free, strengthening waste management in fringe villages, and promoting non-plastic alternatives already used in rural West Bengal. Mukherjee further argues that protected areas themselves need redefining. “Conserved forests should be plastic-free zones. The Sundarbans could become a model, with regular monitoring of microplastics and strict controls on plastic use,” he says.
Dey stresses on the importance of gathering more primary data. “Mapping the levels of impact from source points can raise better awareness for plastic waste management. Enforcement and practical implementation with continued monitoring is always a challenge in the field,” she says.
“Microplastic contamination in larger terrestrial mammals is still understudied. Collaborative research across the country is immediately needed. We want to conduct follow-up studies on the Bengal tiger and other important mammals of the Sundarbans,” adds Mukherjee.
Read more: Study maps microplastics in Mumbai’s mangroves
Banner image: Jungle cat in the Sundarbans. Image by Soumyajit Nandy via Wikimedia Commons (CC BY-SA 4.0).
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