Heavy metal contamination in two commercial fish species of a trans-Himalayan freshwater ecosystem

Toxic metals have disturbed the quality of freshwater ecosystems worldwide. The concentration of heavy metals was investigated in liver, gills and muscle tissues of Schizothorax niger and Cyprinus carpio captured from river Jhelum of Kashmir Himalaya. The heavy metals displayed a wide range of disparity in studied tissues, seasons, sites and species. Cu²⁺ exhibited the highest concentration (279.6 μg/kg) in the liver tissues of S. niger in autumn at site 2 and the lowest (53.1 μg/kg) in the gill tissues in winter at site 1. In C. carpio, the Cu²⁺ was recorded highest (309.4 μg/kg) in the liver tissues in autumn at site 2. The concentration of Zn²⁺ was found highest (575.7 μg/kg) in the liver tissues at site 2 and the lowest (65.8 μg/kg) was recorded in the muscle tissues in autumn at site 1. Zn²⁺ was recorded highest (416.6 μg/kg) in the liver tissues in autumn at site 3 and lowest (51.5 μg/kg) in the gills of C. carpio during winter at site 1 (control). The concentration of Pb²⁺ (14.42 μg/kg) and Fe²⁺ (323.9 μg/kg) was observed in the liver tissue and gills of S. niger at site 3. Similar levels of Pb²⁺ and Fe²⁺ were recorded in the tissues of C. carpio at different sites. Four-way ANOVA (four way) indicated a statistically significant variation (p ≤ 0.05) in heavy metals with the sites, seasons, species and organs. The study emphasises the utmost need to monitor the level of heavy metals in S. niger on a regular basis as this native fish species is showing a continuous decline in the freshwater ecosystems of Kashmir Valley.