Acute Toxicity and Sub-Lethal Effects of Crownquat Herbicide on Water Quality and Behavioural Responses of Juvenile Clarias gariepinus
Year: 2026
Type: article
Abstract: The increasing application of herbicides in agricultural production has raised concerns regarding their adverse effects on aquatic ecosystems through runoff and accidental contamination of water bodies. This study investigated the acute toxicity and sub-lethal effects of Crownquat herbicide on water quality and behavioural responses of juvenile Clarias gariepinus. A 96-hour acute toxicity bioassay was conducted using Crownquat concentrations of 0.50, 1.00, 2.00, 3.00, and 4.00 mL L⁻¹ to determine the median lethal concentration (LC₅₀), while sub-lethal effects were evaluated over a 28-day exposure period at concentrations of 0.095, 0.19, and 0.38 mL L⁻¹. Mortality increased significantly with increasing herbicide concentration, ranging from 20% at 0.50 mL L⁻¹ to 100% at 4.00 mL L⁻¹. Probit analysis estimated a 96-h LC₅₀ value of 1.52 mL L⁻¹, indicating moderate toxicity of Crownquat to juvenile C. gariepinus. Sub-lethal exposure resulted in significant alterations (p < 0.05) in water quality parameters, characterized by reductions in dissolved oxygen, total alkalinity, and total hardness, alongside increases in biochemical oxygen demand, chemical oxygen demand, total dissolved solids, ammonia-nitrogen, and nitrate concentrations. Behavioural responses were concentration-dependent and included restlessness, erratic swimming, increased opercular ventilation, reduced feeding activity, loss of equilibrium, lethargy, and decreased responsiveness to external stimuli. These responses indicate physiological stress and impaired adaptive capacity in exposed fish. The study demonstrates that Crownquat herbicide poses substantial ecotoxicological risks to juvenile C. gariepinus and can adversely affect freshwater ecosystem quality even at sub-lethal concentrations. These findings provide valuable baseline information for environmental risk assessment and support the implementation of sustainable herbicide management practices aimed at protecting aquatic biodiversity and water quality.
Source: IPS Journal of Toxicology
DOI: 10.54117/gfsmtt19
Institution: Federal University of Technology Owerri
Subfield: Health, Toxicology and Mutagenesis
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7166300648
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