A critical review on the effect of nitrate pollution in aquatic invertebrates and fish

Apart from anthropogenic pollution, nitrate contamination is prevalent in practically all developing countries as a result of increased natural activities. The accumulation of nitrates in water bodies causes cumulative effects on living species, environmental receptors, and human vitality by accumulation along the food chain. Nitrates have recently piqued the interest of academics due to their widespread pollution of surface and groundwater systems. The presence of nitrate in high amounts in surface and groundwater causes a variety of health issues, including methemoglobinemia, diabetes, the emergence of infectious diseases, and a negative impact on aquatic organisms. Sensing nitrate is an alternative method for measuring the distribution of nitrate in various bodies of water. The nitrate-laden wastes from agricultural run-off, industrial discharges, and livestock and poultry farms contaminate resources. Nitrate toxicity shows swimming alteration, growth retardation, and eventually death among aquatic organisms. In fishes, it causes histopathological alteration of gills, esophagus, and brain. Therefore, this present review discusses the toxic concentration of nitrates, its adverse effects on the aquatic animals and the assessment of the safe limit of nitrate that is crucial to prevent chronic toxicity among invertebrates and fish. Graphical Abstract