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Aquatic Toxicology
Elsevier B.V.
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Abstract: |
An acute exposure study of mancozeb (MAZ) fungicide was applied on Oreochromis niloticus for 96-h duration.
Three hundred fish (20.50 ± 1.60 g) were assigned into six groups (50 fish/ group; 10 fish/replicate) and
exposed to different six concentrations (0, 4, 8, 12, 16, and 20 mg L 1) of MAZ for 96-h. The Probit analysis
program was used to compute the 96-h lethal concentration 50 (96-h LC50) of MAZ. During the exposure
duration, the fish’s behavior, clinical symptoms, and mortalities were recorded daily. After the exposure period
was ended, the hematological, biochemical, immunological, and oxidant/antioxidant parameters were evaluated.
The results of this study recorded the 96-h LC50 of MAZ for O. niloticus to be 11.49 mg L 1. Acute MAZ
exposure badly affected the fish’s behavior in the form of increased the breath gasping and swimming activity
with aggressive mode. The exposed fish showed excessive body hemorrhages and fin rot. The survival rate of the
exposed fish to MAZ was 100, 80, 66, 50, 38, and 30% in 0, 4, 8, 12, 16, and 20 mg L 1 MAZ, respectively. The
hematological indices (red blood cell count, hemoglobin, packed cell volume%, and white blood cell count) were
significantly decreased by increasing the MAZ exposure concentration (8–20 mg L 1). The acetylcholine esterase
activity and immune indices (lysozyme, nitric oxide, immunoglobulin M, complement 3) were decreased by MAZ
exposure (4–20 mg L 1). Acute MAZ exposure induced hepato-renal dysfunction and elevated stress-related
parameter (cortisol) by increasing the MAZ concentration. A significant reduction in the antioxidant parameters
(total antioxidant activity, catalase, and superoxide dismutase) with increasing the lipid peroxidation marker
(malondialdehyde) was noticed by acute MAZ exposure (4 –20 mg L 1) in O. niloticus. Based on these outcomes,
the MAZ exposure induced toxicity to the fish evident in changes in fish behavior, neurological activity, hepatorenal
functioning, and immune-antioxidant responses which suggest physiological disruption.
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