Aqueous and dietary bioaccumulation of antibiotic tetracycline in D. magna and its multigenerational transfer

The potential bioaccumulation and distribution of antibiotics in non-target organisms have been inadequately studied in spite of their widespread occurrence in aquatic systems. We investigated the ability of tetracycline to bioaccumulate through aqueous and dietary routes in an aquatic organism, the freshwater crustacean Daphnia magna. D. magna was exposed to algal food (Pseudokirchneriella subcapitata) contaminated with tetracycline for dietary uptake. Tetracycline was transferred to D. magna more through aqueous uptake than through dietary uptake. The uptake rate constant of tetracycline for D. magna was kin,water = 0.33 ± 0.045 via the aqueous route and kin,food = 0.16 ± 0.012 via the dietary route for 1.0 mg L−1 tetracycline. Bioconcentration factors of 4.40 ± 0.91 L kg−1 and 3.66 ± 0.50 L kg−1 for 0.1 and 1.0 mg L−1 tetracycline were found for D. magna. The biomagnification factor of 0.19 ± 0.04 indicates that magnification of tetracycline through the food web will not occur. The change in the internal concentration of the target compound was also studied for multigenerational (F1-F4) exposure. The internal concentration in D. magna showed a decreasing trend with increasing generations except for the parent generation. The bioaccumulation tendency showed a biphasic change in multigenerational exposure.