Helminth Parasites as Bioindicators of Heavy Metal Pollution in the Jhelum River: Insights into Bioaccumulation and Ecological Implications

Abstract

Biomonitoring using host-parasite dynamics as bioindicators of heavy metal pollution is limited, particularly in Indian riverine systems. This study explored the potential of helminth parasites of fish as bioindicators and accumulators of heavy metals in the Jhelum River, the largest tributary of the Indus River. Samples were collected seasonally over 12 months (June 2022–May 2023). Concentrations of five heavy metals (Fe, Zn, Cu, Pb, Cd) were assessed in Schizothorax niger tissues (liver, intestine, muscle) and helminth parasites (Pomphorhynchus kashmirensis, Schyzocotyle acheilognathi, Adenoscolex oreini) using Atomic Absorption Spectroscopy. Statistically significant differences (p < 0.01) were observed for all metals across seasons, sites, tissues, and parasitic fauna (Three-way ANOVA). The bioaccumulation hierarchy was P. kashmirensis > S. acheilognathi > A. oreini > liver > intestine > muscle. Cd and Pb were absent in fish muscle tissue but highly concentrated in parasites, demonstrating their superior bioaccumulation capacity. Higher bioconcentration factor (BCF) for Cd and Pb were noted in parasites. Principal Component Analysis (PCA) and graphical visualizations further confirmed the distinct clustering of parasites due to elevated metal uptake. These findings underscore the ecological and toxicological implications of heavy metal pollution and highlight helminth parasites as effective bioindicators of contamination. This study advances insights into trophic transfer and provides a framework for sustainable monitoring and management strategies to protect aquatic biodiversity and food safety in polluted ecosystems.

Graphical Abstract