Integrated assessment of heavy metal pollution: Bioaccumulation in the river snail Filopaludina martensi, sediment, and water from the Mae Kha Canal, Chiang Mai province, Thailand

Cadmium (Cd) and lead (Pb) tend to bioaccumulate in freshwater environments, making them major hazards to environmental health. This study aimed to determine the content of the heavy metals Cd and Pb in field sediment, water, and whole tissues of the edible river snail Filopaludina martensi , which could serve as bioindicators for these metals. Principal component analysis (PCA), Permutational multivariate analysis of variance (PERMANOVA), and Pearson correlation coefficients (r) showed that heavy metals and snail populations are greatly impacted by seasonal variations (p < 0.05). The upstream section had healthier conditions compared with the midstream section, owing to the impact of anthropogenic activities. The wet season showed the highest Cd and Pb concentrations (p < 0.05) in all samples. The sediment samples had the highest Cd and Pb concentrations, followed by the snail and water samples (p < 0.05). The heavy metal concentrations in the sediment and river snail samples showed a strong correlation (PCA; p < 0.05). Importantly, the Pb concentrations in the snail samples were higher than the recommended threshold, indicating that these snails should be consumed with extreme caution. Both Cd and Pb damaged the snail digestive glands, and which may have caused DNA damage. These findings indicate that F. martensi is a reliable bioindicator of the ecological integrity of the Mae Kha Canal. Evidence of biological degradation and ongoing metal contamination in the canal emphasizes the value of using these snails for pollution monitoring and directing pollution management efforts to maintain aquatic ecosystems and public health.