Veterinary bacteriostatic and ionophore antibiotics in aquatic organisms: A systematic review and scientometric analysis of biomarker and exposure concentrations

The intensive use of veterinary antibiotics, particularly bacteriostatic agents and ionophores, represents an increasing ecotoxicological concern for aquatic ecosystems. This study integrates scientometric analysis with a systematic literature review specifically aimed at identifying gaps in experimental research addressing the effects of these pharmaceuticals on aquatic organisms through biomarker-based assessments. A total of 648 publications published between 1968 and 2024 were screened; however, only 20 in vivo studies involving 10 aquatic species (7 vertebrates and 3 invertebrates) met the inclusion criteria, of which 17 investigated bacteriostatic antibiotics and 3 ionophores. Acute exposure designs predominated (35 %), followed by subchronic (30 %), chronic (15 %), and combined acute–chronic (20 %) assays. Reported environmental concentrations ranged from nanograms to hundreds of micrograms per liter, whereas experimental exposures frequently reached milligram-per-liter levels — in some cases exceeding environmental concentrations by several orders of magnitude. Observed effects included oxidative stress, immunological alterations, reproductive impairment, embryotoxicity, and histopathological damage. The findings demonstrate a disproportionate reliance on standard model organisms, particularly Danio rerio, and a notable scarcity of studies involving native or ecologically relevant species. This review highlights a critical need for future research to adopt chronic exposure scenarios, incorporate native species, environmentally relevant concentrations, and apply standardized- sensitive biomarkers. Addressing these gaps is essential to advance the environmental risk assessment of veterinary antibiotics and to support more effective and evidence-based environmental policymaking.