Plasma Electrolytes Response in Mud Catfish, Clarias gariepinus (Burchell 1822) exposed to Different Regimes of Salinity and pH

Introduction: Aquatic organisms, especially fish, are highly sensitive to environmental changes that can profoundly affect their physiological processes essential for survival. Physico-chemical factors such as salinity and pH exert significant influences on osmoregulation and ion balance, which are critical for maintaining cellular homeostasis in fish. Aims: This study aims to explore how varying levels of salinity and pH affect plasma electrolyte concentrations in Clarias gariepinus, focusing on potassium (K+), sodium (Na+), chloride (Cl−), and bicarbonate (HCO3−) ions. The objective is to understand the physiological responses of C. gariepinus to these environmental factors and their potential as biomarkers for assessing aquatic ecosystem health. Materials and Methods: Juvenile C. gariepinus was exposed to different salinity levels (4 ‰, 6 ‰, 8 ‰) and pH levels (4, 6, 8) over 21 days. Plasma electrolyte concentrations were measured using an SFRI ISE 6000 Electrolyte Analyser. Statistical analysis included ANOVA and DMRT to identify significant differences (p < 0.05) among experimental groups. Results: The study found significant variations in K+, Cl−, Na+, and HCO3- concentrations in C. gariepinus across different salinity and pH conditions. K+ levels decreased with increasing salinity, indicating stress-induced responses, while pH variations had less pronounced effects on K+ regulation. Cl− concentrations increased with higher salinity levels, suggesting adaptive osmoregulatory strategies. Na+ levels showed significant fluctuations across salinity and pH conditions, whereas HCO3− levels responded uniquely to changes in these parameters, demonstrating adaptive mechanisms in acid-base balance. Conclusion: This research underscores the adaptive responses of C. gariepinus to fluctuations in salinity and pH, highlighting their ability to maintain plasma electrolyte balance under varying environmental conditions. These findings contribute to understanding the ecophysiological adaptations of C. gariepinus and suggest the potential utility of plasma electrolytes as biomarkers for assessing the health of aquatic ecosystems.