Study on Keralam ELSA-3 shipwreck shows persistent nurdle pollution, evolving ecological impacts

A scientific study following the sinking and spill from the container vessel MSC ELSA-3 off the coast of Keralam last year has provided evidence of persistent nurdle pollution and evolving ecological impacts along Keralam and Tamil Nadu coasts.

India experienced its first documented large-scale marine resin pellet spill following the sinking of the Liberian-flagged container vessel MSC ELSA-3 off the Keralam coast in May 2025. The vessel was carrying approximately 640 containers loaded with plastic resin pellets, industrial materials, and hazardous cargo including calcium carbide, together with substantial quantities of diesel and furnace oil.

In the aftermath of the accident, the Tamil Nadu Pollution Control Board (TNPCB) initiated short term (rapid) and long term (two years) impact assessment studies through Suganthi Devadason Marine Research Institute (SDMRI) in Thoothukudi.

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The SDMRI has published the one-year study results on impacts in the ‘Marine Pollution Bulletin’ journal.

Nurdle (plastic pellet) spills are recognised as sources of primary microplastic pollution, yet their long-term environmental transformation and ecological implications remain poorly understood. The study was aimed to characterise the spatial and temporal persistence, environmental weathering, contaminant accumulation, microbial colonisation, and biological interactions of spill-derived nurdles following the MSC ELSA-3 incident.

Contamination was monitored for one year across 93 coastal sites along India’s southwest and southeast coasts using shoreline surveys, sediment coring, polymer and surface characterisation, contaminant analysis, microbial assessment, and fish examination, says J.K. Patterson Edward, director, SDMRI.

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The study showed shoreline abundance reached 31,230 items m2 after the spill and declined by >80% within three months at impact sites, while new hotspots emerged by October 2025, reaching 10,875 items m2 on the Gulf of Mannar mainland and 2960 items m2 on islands. By May 2026, nurdles persisted and were found buried to 20 cm in beach sediments.

Buried pellets could remain in sediments and potentially be remobilised by erosion, storms and sediment reworking. Recovered pellets showed progressive physical and chemical transformation, with surface deterioration, increasing yellowing and oxidation detected by FTIR and scanning electron microscopy, the report revealed.

Weathered nurdles also accumulated environmental contaminants, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons and polychlorinated biphenyls (PCBs), persistent pollutants of environmental concern. The progressive colonisation of weathered pellets resulted in the development of a “plastisphere” of microbial life, including bacteria of potential pathogenic significance.

Although freshly stranded pellets showed only low levels of microbial colonisation, pellets exposed to the environment for several months showed a marked increase in bacterial abundance, frequently exceeding 100,000 - 1,000,000 colony-forming units per gram, particularly during the monsoon and post-monsoon periods, Mr. Edward said.

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Also, nurdles were detected in 26 of 2413 fishes (1.08%) primarily through gastrointestinal ingestion, with occasional gill entrapment. Pristine nurdles caused minimal physiological disturbance, whereas weathered contaminant-enriched nurdles were associated with elevated oxidative stress and histopathological alterations, said K. Immaculate Jeyasanta, one of the authors.

These findings provide evidence of environmental transformation and ecological relevance of spill-derived nurdles. The continued distribution of nurdles along shorelines and their ingestion by marine fish till date, highlight the need for long-term monitoring and spill management., Mr. Edward stressed.