Ecological risk profiling of microplastic load in commercial aquaculture of Bangladesh: A multi-approach analysis across species-specific ponds
Malek Ali, Md Anisuzzaman, Jahanara Akhter Lipi, Khadijatul Kubra Riya, Takaomi Arai, Norhayati Ngah, M. Belal Hossain
Abstract
Bangladesh, a leading fish-producing nation, faces limited understanding of the ecological risks posed by microplastic (MP) pollution in its freshwater aquaculture. This study evaluated MP load, polymer-specific toxicity, and cumulative ecological risks across species-specific ponds (Tilapia, Pangas, Indian Major Carp, Gulsha, and Koi) using an integrated multi-index assessment framework. The mean MP abundance was 520.5 ± 80.3 items/m³, with the highest concentration in Pangas Pond water (728.5 items/m³). MPs were predominantly fibers (<0.5 mm), with five polymer types, PE, PP, PET, PS, and EVA, indicating contamination from both direct sources and indirect sources. The Pollution Load Index was >1 in Pangas, Koi, and Tilapia ponds, representing substantial anthropogenic input. Polymer Hazard Index (PHI) indicated medium ecological risk, with the highest values observed in Pangas and Koi ponds due to the presence of more hazardous polymers, whereas Indian Major Carp ponds showed the lowest PHI. The Potential Ecological Risk Index (PERI) also identified Pangas ponds as the most ecologically stressed, followed by Koi. The Toxicity Index (Tim) values were highest in Pangas and Koi ponds due to the prevalence of small, fiber-shaped, dark-colored MPs, enhancing bioavailability and ingestion risk. Finally, Multi-characteristics PERI (MPERI), integrating PLI and Tim, revealed the highest ecological risk in Pangas ponds (mean: 30.62), followed by Koi and Gulsha, while Indian Major Carp ponds showed the lowest risk (mean: 19.54). Overall, the results highlighted that Pangas and Koi ponds are ecotoxicologically more vulnerable to MP pollution due to their higher contaminant loads and more hazardous particle characteristics.