Microplastics (MPs) persist in aquatic ecosystems, posing risks to marine life and humans via bioaccumulation and trophic transfer. Mangroves can serve as reservoirs for MPs, potentially impacting conservation and restoration. This study investigates MPs contamination in fish at the Anavilundawa Accelerated Natural Regeneration of Mangroves (ANRM) site in Sri Lanka, now in its fifth year of restoration.
Three fish species namely Carangoides fulvoguttatus (carnivore), Chanos chanos, and Oreochromis mossambicus (omnivores) were collected from water channels during November–December 2024 and their gut and muscles were extracted. Extracted tissues from five specimens of each species between 12–20 cm total length underwent organic digestion (10% KOH, 60°C, 24 hrs), density separation (NaCl, 1.2 g/ml), and filtration (0.45 µm filters). MPs were characterized by shape, size, color, and abundance under a stereo zoom microscope. One-way ANOVA revealed significant differences in gut contamination , mainly due to higher levels of MPs in C. fulvoguttatus (±SD) (1.89 ± 0.81), as confirmed by Tukey’s test (p<0.05). No significant differences were found in muscle tissue MPs across species. Only filaments were observed in all species. Paired t-tests between gut and muscle tissues showed no significant differences, except a suggestive one-tailed significance for higher levels of MPs in gut of C. fulvoguttatus. Blue and transparent filaments were most common, especially in the muscles of O. mossambicus.
These findings represent the first evidence of MPs contamination in fish within this mangrove restoration area, highlighting the need for further surveillance of MPs in mangrove ecosystems.