Experimental study on the bioaccumulation of oxytetracycline and oxolinic acid by the blue mussel (Mytilus edulis). An evaluation of its ability to bio-monitor antibiotics in the marine environment

The ability of blue mussel (Mytilus edulis) to act as a potential antibiotic bioindicator in marine waters was experimentally tested by the study of the kinetics of two veterinary antibiotics (oxolinic acid: OA and oxytetracycline: OTC). Antibiotic uptake was fast in the soft parts of the mussels. OA was quickly eliminated while OTC was released more slowly (half-life in VISCERA=3.9 days). OA and OTC were preferentially accumulated in gills and in viscera, respectively. Bio-accumulation factors were low (maximum: 2 for OTC in viscera) in accordance with the low Kows. It was assumed that the higher OTC bioaccumulation pattern was related to its binding to mineral and organic compounds that led to its activity inhibition (62%). The antibiotics were persistent in shells (OTC HALF-LIFE=8.3 days). Most veterinary and human antibiotics such as tetracyclines and sulphonamides have low logKow (<2) and should weakly accumulate in mussel. This might limit the use of blue mussel to bio-monitor antibiotics in the marine environment.