Threatening the Near–Threatened: Microplastics in Jerdon's Catfish (Mystus malabaricus), Endemic to the Global Biodiversity Hotspot, the Western Ghats of India

Abstract

Microplastic contamination in freshwater fish poses a significant global threat but remains underexplored in biodiversity hotspots like the Western Ghats of India, where rivers exhibit elevated microplastic levels. This study investigates microplastic contamination in the endemic and near-threatened bagrid catfish, Mystus malabaricus, sampled from the Ulhas River, Maharashtra. Microplastics were isolated and analysed for physical attributes (size, shape, colour) using light microscopy and for chemical composition through µ-Raman spectroscopy. Our findings indicate that 50% of the catfish contained microplastics, averaging 2.54 ± 0.41 particles per fish, with five morphotypes identified, predominantly transparent and grey films made of polyethylene (89.3%) and polypropylene (10.7%). The observed characteristics of microplastics reflect a direct relationship to secondary anthropogenic sources, revealing inadequacies in regional waste management infrastructure. This contamination may adversely affect fish development and pose risks to fish consumers and artisanal fisheries. We propose mitigation strategies based on the findings of this and previous studies on the Ulhas River.