AbstractThe levels of emerging chemicals have increased dramatically during the last two decades posing problems for human and environmental health. Pain-killers such as ibuprofen and antibiotics such as amoxicillin are generally consumed together and hence are discharged into waterbodies as effluents. The lack of a rigorous control of pharmaceutical discharges into natural waterbodies is a concern for limnologists and ecotoxicologists because of their possible effects on non-target organisms. Rotifers, due to their sensitivity, short generation time and high reproductive rates, are widely used as bioassay organisms in testing the effects of different substances including pharmaceuticals. Here we quantified the demographic responses of Brachionus calyciflorus and Brachionus havanaensis exposed to three sublethal concentrations of ibuprofen (25, 12.5 and 6.25mgL−1) and amoxicillin (200, 100 and 50μgL−1). Our data showed that both survivorship- and reproduction-related variables were negatively affected with increasing concentrations of both pharmaceuticals. The rate of population increase of B. calyciflorus (0.63–0.72d−1) was not affected by amoxicillin or by ibuprofen but for B. havanaensis, it was decreased significantly (from 0.89 to 0.38d−1). Compared to ibuprofen, amoxicillin had more adverse effects on both the rotifer species.