Chronic ecotoxicity of ciprofloxacin exposure on taxonomic diversity of a meiobenthic nematode community in microcosm experiments

A laboratory bioassay was performed to assess the ecotoxicity of ciprofloxacin on a meiobenthic nematodes community from Bizerte lagoon (NE Tunisia). Four ciprofloxacin doses [D1 (50 µg/g), D2 (100 µg/g), D3 (200 µg/g), and D4 (500 µg/g)] were applied to the substrate, and responses were studied after one month. Discernible differences were observed between control assemblages and those populating ciprofloxacin treated substrates. All univariate indices were affected significantly compared to those in the control microcosm with increasing antibiotic concentration. The non-parametric Multi-Dimensional Scaling based on species abundances (MDS) showed significant separation of the control microcosm from the antibiotic-treated populations. The nematode species responses to the fluoroquinolone treatments varied: Odontophora villoti was reduced at all concentrations of ciprofloxacin and was considered “sensitive,” whereas Metoncholaimus pristiurus was affected by moderate concentrations; its abundance increased with the highest dose D4 and was described as “opportunistic.” Paramonohystera pilosa, whose abundance increased with antibiotic doses appeared “resistant.” Keywords: Meiobenthic nematodes, Susbstrate, Antibiotic, Ciprofloxacin, Exposure, Bioassay