Ascorbic Acid Effect on Glyphosate-induced Haematological and Serological Pathology in Juveniles of the Catfish Clarias gariepinus (Pisces: Clariidae) Burchell, 1822

Aims: The study was to determine the effects of sub-lethal concentrations of glyphosate-based herbicide (Delsate®) on blood parameters, serum enzymes and urea of Clarias gariepinus juveniles as well as therapeutic effect of Vitamin C(Kepro®)on the glyphosate-induced pathology.

Study Design: Latin square.

Place and Duration of Study: Department of Fisheries and Aquaculture Management, Nnamdi Azikiwe University Awka. Nigeria, between December 2018 and April 2019.

Methodology: A 48 hours-acute toxicity tests were initially done to determine the respective LC50 of Delsate® and Kepro® using 8 C. gariepinus juveniles of mean weight 41.50±1.35 g and mean length 20.75±0.43 cm. Thereafter one group of C. gariepinus juveniles (n=144) was exposed to 0, 5, 10 and 15mgL⁻¹ sub-lethal concentrations of Delsate® for 91 days followed by different treatments with 50mgL⁻¹ and 100mg L⁻¹ of the vitamin C after 7 days post exposure to glyphosate. Another group of C. gariepinus juveniles (n=144) were exposed concurrently to glyphosate and vitamin C for 91 days.

Results: The LC50 of Delsate® was 75 mgL⁻¹ and Kepro® 175 mgL⁻¹. There was significant decrease (P<.05) in PCV, Hb, RBC and AST of glyphosate-exposed groups when compared with Control. No significant difference occurred between TWBC, DWBC and ALP of exposed and control groups, except in neutrophils where significant increase occurred in ALT and urea. Treatment with 50 and 100mgL⁻¹ vitamin C in glyphosate-exposed groups showed significant increase in PCV, Hb, RBC and ALP with a decrease in mean AST, ALT and Urea The 100 mgL⁻¹ produced better therapeutic benefit than 50 mgL⁻¹ vitamin C. However, concurrent exposure to glyphosate and vitamin C indicated no significant therapeutic effect on the tested blood and serum parameters.

Conclusion: The LC50 of Delsate® and Kepro® for catfish have been determined. Delsate® toxicity induced perturbations in some haematological and biochemical parameters in fish. The level of ascorbic acid (100 mgL⁻¹ Kepro®) used in this study enhances catfish tolerance to environmental stress and could reduce Delsate® toxicity.