A comparative study of microplastic detection in Nemipterus japonicus, Rastrelliger kanagurta, Arius sp. and Scylla olivacea from Chennai Coastal Region, India using ATR-FTIR spectroscopy

Microplastics (<5 mm) are omnipresent pollutants produced directly or generated because of larger plastic particle breakdown. The challenge of microplastic pollution is an emerging global concern, with India being no exception. This study investigated the prevalence and characteristics of microplastics in four commercially important aquatic species from two distinct ecosystems in Tamil Nadu, India viz., the Ennore Creek (brackish water) and the Kasimedu landing center (marine). The species examined were catfish (Arius sp.), mud crab (Scylla olivacea), Japanese threadfin bream (Nemipterus japonicus) and Indian mackerel (Rastrelliger kanagurta). Microplastics were detected in 78.57% of the 70 samples analyzed, with Nemipterus japonicus and Arius sp. showing the highest average ingestion of 5±3 and 4±2.5 microplastic items per individual respectively. A distinct organ-specific trend was observed, with gills harboring slightly more microplastics (0.35 items/gills) compared to guts (0.21 items/gut). Fibers and fragments were the predominant microplastic shapes, while offwhite (translucent), white, blue and black were the most common colors detected. ATR-FTIR analysis identified low-density polyethylene (LDPE) and polyamide (nylon) as the primary polymer types. The research underscores considerable interspecies and species-specific variations in microplastic accumulation and dispersion, underscoring the necessity for precise, species-specific evaluations to comprehend the potential ecological and anthropogenic health ramifications of this escalating environmental issue. Recommendations include establishing comprehensive monitoring programs, implementing source reduction strategies, enhancing habitat conservation, and fostering collaborative research to address microplastic pollution in the studied ecosystems.