Cumulative effect of chronic thermal stress and glyphosate based herbicide exposure on blood parameters and cortisol levels of common carp (Cyprinus carpio).

Climate change and environmental pollution can alter the composition and productivity of biological communities in aquatic ecosystems. Sensitive species are at more risk due to these stressors, which can affect their physiology with adverse effects on their health and reproduction. Co-exposure to multiple environmental stressors may have synergistic effects on the health of aquatic animals. Therefore, present research was designed to explore the cumulative effect of chronic exposure to thermal stress and glyphosate-based herbicide on the hematological parameters and cortisol level of common carp (Cyprinus carpio). Twenty-eight common carp were exposed to thermal stress (30 and 32 °C temperature) and a sub-lethal concentration of glyphosate for 28 days. A significant increase in white blood cells (WBCs), platelets and cortisol was observed in fish exposed to the sub-lethal concentration of glyphosate, while red blood cells (RBCs) and hemoglobin (Hb) decreased. Cortisol levels of fish exposed to thermal stress (32 °C) increased significantly. RBCs, WBCs, platelets, hemoglobin concentration and cortisol levels increased significantly in fish co-exposed to thermal stress and a sub-lethal concentration of glyphosate. It was concluded that co-exposure to glyphosate and thermal stress causes physiological impairments in common carp.