Synergistic effects of thermal stress and 4-nonylphenol on oxidative stress and immune responses in juvenile tilapia (Oreochromis niloticus)

Aquatic ecosystems face multiple stressors, including thermal fluctuations and chemical pollutants, which can detrimentally impact fish health and ecosystem integrity. This study investigates the individual and combined toxic effects of 4-nonylphenol (4-NP) and thermal stress on juvenile tilapia fish (Oreochromis niloticus). Four groups of fish were exposed to different stressors for 15 days: control, thermal stress (35 °C ± 1 °C), 4-NP exposure (1 mg/L), and a combination of thermal stress and 4-NP. Results reveal significant alterations in antioxidant enzyme activity, lipid peroxidation levels, and cytokine expression in response to stressors. Thermal stress and 4-NP exposure disrupt antioxidant defense mechanisms and increase oxidative stress. Thermal stress profoundly affects fish health and metabolism, impacting physiological functions and immunity. Thermal stress induces reactive oxygen species production, triggering antioxidant responses and affecting immune parameters. Exposure to 4-NP exacerbates oxidative stress, further compromising fish health. The observed increase in pro-inflammatory cytokines implies an immunostimulatory reaction to stressors. These findings underscore the complex interactions between environmental stressors, immune responses, and fish health. Further research is needed to fully understand these interactions and their implications for aquatic ecosystems. Implementing these biomarkers in ecological risk assessments can provide insights into the impacts of environmental stressors and inform conservation and management strategies in aquaculture.