Ecotoxicological effects of heavy metal contamination on reproductive health and gamete quality in female Nile tilapia (Oreochromis niloticus) from the Brantas River Basin, Indonesia.

Background and aim: Heavy metal pollution in freshwater ecosystems poses a serious threat to aquatic biodiversity and food safety. This study assessed the bioaccumulation of lead, cadmium (Cd), iron (Fe), and copper, as well as their effects on histopathological alterations in vital organs and gamete quality, in female Nile tilapia (Oreochromis niloticus) from the Brantas River Basin, East Java, Indonesia.

Materials and methods: Water and fish samples were collected from five sites with varying levels of industrial and residential activity. Heavy metal concentrations were analyzed through atomic absorption spectrophotometry. Histopathological evaluations were performed on gills, liver, and ovaries, and gamete quality was assessed based on oocyte diameter, germinal vesicle breakdown (GVBD), survival, and abnormality rate. Statistical analyses included a one-way analysis of variance, Kruskal-Wallis tests, and Spearman correlation.

Results: The highest concentrations of Cd and Fe were found in Kalisari, corresponding with pronounced histopathological lesions in fish, including necrosis, inflammation, and hyperplasia in vital organs. Oocytes from heavily polluted sites exhibited significantly reduced diameters, GVBD rates, and survival rates, alongside increased abnormalities. Cd and Fe levels exhibited strong positive correlations with organ damage and negative correlations with gamete quality, particularly oocyte survival (Fe: r = -0.900).

Conclusion: Exposure to elevated levels of Cd and Fe significantly impairs the physiological and reproductive health of female Nile tilapia in the Brantas River. The observed tissue damage and reproductive disruption underscore the ecological and public health risks associated with unchecked industrial discharge. Long-term biomonitoring and targeted pollution control strategies are urgently required to safeguard aquatic life and reduce health risks under the One Health framework.