Micro-estuaries are water bodies with a surface area lower than one square kilometer which are common in Mediterranean climate regions. As a result of their limited area these ecosystems are sensitive to external influences one such possible influence is chemical pollution by pharmaceuticals. The variable nature flow regimes which is composed of low base flows mixed with treated effluents and storm water events which may drain pharmaceutical substances from vast urban and agricultural areas may lead to degradation of the estuarine ecosystem which will prevent the supply of estuarine ecosystem services. Therefore, the Israeli estuarine research center conducted a survey of pharmaceuticals concentrations in the Alexander estuary using a HRMS. pharmaceutical residues were found in all of the 280 water samples, with maximal concentration of 14 and 18 mg/L (sum of all pharmaceuticals) during baseflow and storm water events. The accumulated toxicity for fish, crustaceans and algae was 1960
5, 520% and 450% the toxic threshold, which indicates high toxic potential. The anti inflammatory Ibuprofen, the anticonvulsant Carbamazepine and caffein were identified as the most toxic to the ecosystem and as toxic to different taxonomic groups in the Alexander estuary.
The research findings show the high exposure of the micro-estuarine ecosystem to pharmaceuticals and emphasis the high toxicity anthropologically inflicted on these ecosystems.