Effect of sand mining on fish diversity and histopathology health in Sone River, Bihar, India

Rivers are critical element of freshwater ecosystems which have started to come under threat due to the unregulated and unscientific sand mining happening in the rivers. Such activities are posing a danger to the bio-diversity, as well as the surface and groundwater resources. The goals and objectives of the study included the examination and assessment of the impacts of sand mining on the bio-diversity and the histopathological conditions of the fish in the river Sone at the location of Bihar, India. The present research included a whole-year research plan consisting of five sampling zones distributed over three mining zones. These zones included the Heavy Mining, the Moderate Mining, and the Control or No Mining zones. At the same time, the bio-diversity of the fish was additionally measured quantitatively with the aid of biodiversity indexes. The results obtained revealed that a significant gradient in the zones was visible pertaining to the ecological conditions. Fish bio-diversity was also quantitatively done through biodiversity indexes. Results revealed a clear gradient of ecological condition in the different mining intensity zones. It was evident that the Control Zone was the most diverse zone within the river, comprising 23 species and on the other hand, the Heavy Mining Zone showed a sharp loss in biodiversity and comprised 11 species. The histopathological examination revealed progressive degeneration of tissues with the increase in mining intensity. Fish from the Heavy Mining Zone had severe lesions in gills as lamellar fusion, epithelial lifting, aneurysm, and necrosis; liver as vacuolation, congestion, fatty degeneration; and kidney as tubular shrinkage, hemorrhage, and necrotic glomeruli, indicating impairment of respiratory, metabolic, and excretory functions. Fish of the Moderate Mining Zone exhibited moderate alterations, while Control Zone fish exhibited the least alterations with more or less normal tissue architecture. The integrated decrease in biodiversity indices alongside an increase in the histopathological severity scale shows that sand mining imposes cumulative and long-term stress on the riverine ecosystem. These findings underscore the urgent need for sustainable extraction practices, increased stringency of regulatory enforcement, and ecological restoration strategies to safeguard fish biodiversity with a view to maintaining ecological integrity of the Sone River.