Mangrove under siege: Microplastic contamination, shrimp farming weakening Pichavaram’s ecosystem

Global plastic pollution has widespread impact on marine life and mangrove ecosystems are showing signs of distress. New research in a coastal village of Tamil Nadu detected contamination in aquatic species, indicating the magnitude of the problem.

Pichavaram is a small coastal village in the Cuddalore district of Tamil Nadu, located between the Vellar and Coleroon estuaries along the Bay of Bengal. The Pichavaram mangrove forest, one of India’s largest mangrove ecosystems and a designated Ramsar site, spreads across a complex network of tidal channels, mudflats and dense vegetation. This biotope supports remarkable biodiversity, including around 177 species of resident and migratory birds, and sustains local fishing communities who depend on its waters for livelihood.

Recent research by Bharathidasan University, published in the journal Chemosphere, found significant seasonal microplastic contamination in Pichavaram’s aquatic species. Microplastics, defined as plastic particles smaller than five millimetres, originate from the breakdown of larger plastic waste or from synthetic textiles, packaging and fishing gear.

The monsoon season recorded the highest levels, largely due to runoff from nearby settlements. Species such as Liza tade showed notable particle ingestion, and shellfish including Scylla serrata and Portunus sanguinolentus, were also affected. A substantial proportion of particles were below one millimetre, with blue fibres dominant. Common polymers included polypropylene, polyethylene and PET, confirming that contamination is systemic and widespread. 

Ecologically, the mangroves form a vital buffer between land and sea. They protect inland settlements from cyclones, storm surges and tidal flooding. Their importance became especially clear during the 2004 Indian Ocean tsunami, when areas shielded by dense mangrove cover experienced comparatively less damage. Mangroves are more than forests; they are living coastal defenses.

Globally, mangroves cover about 15 per cent of the world’s coastlines. However, nearly half of all mangrove ecosystems are at risk of collapse due to coastal development, aquaculture expansion and pollution. Of the 36 mangrove ecosystems assessed in the IUCN Red List, Pichavaram is among the critically endangered zones. Its degradation is therefore not merely a local concern but part of a broader global environmental crisis.

Mangroves function like natural coastal kidneys. The unique structure of mangrove roots, known as pneumatophores, slows tidal currents and traps organic matter, debris and sediments. This makes them highly efficient filters but it also means plastic debris and microplastics settle within their root systems. Plastics from nearby settlements enter estuarine waters, move through mangrove channels and become embedded in sediments. They accumulate, absorb heavy metals and enter fragile aquatic nurseries. As plastic pollution weakens mangroves, fisheries, shoreline stability, health and local livelihoods are all placed at risk. 

Historically, Pichavaram’s mangroves served as nurseries for fish, prawns and crabs while protecting the coastline from storms. However, in recent decades, the ecosystem has faced mounting pressures from shrimp farming, land conversion, unregulated tourism and rising plastic waste. When mangroves are degraded due to cutting, pollution or reduced freshwater inflow, their ability to stabilize sediments weakens, creating a feedback loop: increased plastic inflow raises contamination, while stressed mangroves lose resilience.

The ecological consequences of microplastic contamination, thus, are serious. Microplastics alter sediment composition and may interfere with nutrient exchange, affecting mangrove seedling growth. Benthic organisms such as worms and crustaceans, which maintain soil health, are also disrupted. Gradually, the forest’s regenerative capacity weakens.

Through bioaccumulation and biomagnification, microplastics and associated toxins build up along trophic levels. Larger fish that consume contaminated prey accumulate higher toxin levels, which eventually reach humans. For local communities, especially fisherfolk, the impacts are immediate. Fish and shellfish that ingest microplastics often exhibit reduced growth, reproductive disorders and increased mortality. 

Since many families depend almost entirely on small-scale fishing, even minor declines in stock threaten economic security. There is also the risk of reduced consumer confidence if seafood is perceived as contaminated. Women engaged in fish cleaning and processing face prolonged exposure, while children may be particularly vulnerable to long-term health risks. Studies increasingly link microplastic exposure to inflammation, hormonal disruption and toxicity. Thus, in Pichavaram, ecological degradation directly intersects with public health and livelihood concerns.

Geospatial research by the Symbiosis Institute of Geoinformatics shows that while about 610 hectares of mangroves remain stable, 238 hectares are degraded and nearly 369 hectares are regenerating. These figures reflect both ecological stress and potential for recovery under strong human pressure.

Government initiatives have begun addressing restoration. Under the Tamil Nadu Coastal Restoration Mission, launched in 2025 with World Bank support, large-scale mangrove restoration efforts are underway. A significant innovation is the tidal mangrove nursery established at Killai, where saplings of native species are raised on floating platforms under natural tidal conditions before transplantation. This improves survival and resilience once the saplings start taking root.

However, enforcement of plastic regulations remains inconsistent. Waste segregation systems are weak in rural areas, and livelihood pressures often drive short-term economic decisions that harm the ecosystem. Scientific monitoring of microplastic levels is also limited.

A comprehensive response must therefore combine restoration with pollution control. Mangrove reforestation alone cannot succeed if contamination continues. An integrated microplastic monitoring system, in collaboration with local universities, should regularly test water, sediment and seafood. Waste management infrastructure in nearby towns must be strengthened through decentralised segregation units, stricter regulation of single-use plastics and incentives for recycling. Women’s self-help groups can be engaged in collection and recycling efforts, linking environmental protection with income generation.

Community participation is essential. Fishing communities should be involved as custodians of restoration projects, trained in nursery management and eco-tourism. Health awareness programmes and financial support during lean fishing seasons can reduce vulnerability.
Protecting Pichavaram’s mangroves is not simply about conserving trees; it is about preserving coastal resilience, public health and livelihood security. If pollution and degradation continue unchecked, the natural armor that once shielded the coast may slowly weaken. But with integrated action and community engagement, recovery remains possible.

Ankita Rai is a student of School of Planning and Architecture, Vijayawada. Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.