Antibiotic residues in farmed fish and sediments from cage aquaculture: Insights from Stratum II of the Volta Lake, Ghana

Introduction: Antibiotics are commonly used to treat infections and promote fish welfare in Aquaculture. Reports suggest that the use of antibiotics in fish farming often breaches established protocols, frequently accumulating in fish muscles and sediments. These residues are known to be detrimental to the fish, altering antioxidant activity and immune responses, and posing environmental risks. In this study, we aimed to investigate the presence, types and quantify, quantify the levels of antibiotic and residues in Nila tilapia (Oreochromis niloticus) fish muscles and sediment samples, and evaluate the associated health risks to humans and the aquatic ecosystem in Stratum II of Lake Volta, Ghana. Methodology: Muscles of table-sized fish and sediment samples were collected from cage aquaculture farms along the Stratum II of the Lake Volta, Ghana, and analysed using Liquid Chromatography with tandem mass spectrometry (LC-MS-MS) for the presence of antibiotic residues. Variations in residual antibiotic concentrations and basic sediment properties throughout the various strata of the Lake Volta were examined using analysis of variance (ANOVA) with a general linear model (GLM). A post-hoc test for multiple comparisons with a significance level of p < 0.05 was performed using Tukey's HSD technique. Potential antibiotic sources were examined using principal component analysis (PCA). Possible risks to human health and the environment were estimated using risk quotients described in the European Technical Guidance Document on Risk Assessment. Results: Four antibiotics, namely ciprofloxacin, tetracycline, chloramphenicol, and azithromycin, were identified in both fish muscle and sediments, with Azithromycin, tetracycline, and ciprofloxacin residues being the most frequently detected antibiotics. Except ciprofloxacin which showed higher concentration midstream, the rest showed higher concentrations of the detected antibiotic residues from downstream sites. Risk analysis of antibiotic residues in fish muscle tissues and sediments revealed risk quotients that ranged from 0.0024–0.0382 for humans and from 0.0200 – 0.5713 for the aquatic ecosystem in the Lake. Discussion and conclusion: The detection of antibiotic residues in both fish muscle and sediment from aquaculture farms along Lake Volta suggests evidence of antibiotic use or contamination in fish farming in the Lake Volta. Though current antibiotic levels may not pose immediate risks, their accumulation, particularly Chloramphenicol, which has been banned for use in aquaculture, could contribute to antimicrobial resistance making it difficult for future treatment of human infection as well as compromising the food quality and safety.