Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive

The European Water Framework Directive 2000/60/EC (WFD) has been implemented over the past 20 years, using physicochemical, biological and hydromorphological elements to assess ecological status of surface waters. Benthic diatoms (i.e., phytobenthos) are one most common quality (BQEs) used in water monitoring particularly successful detecting eutrophication, organic pollution acidification. Herein, we reviewed their implementation river biomonitoring for purposes WFD, highlighting advantages disadvantages other BQEs, discuss recent advances that could be applied future biomonitoring. Until now, phytobenthos have intercalibrated by vast majority (26 out 28) EU Member States (MS) 54% total bodies assessed was commonly BQE after benthic invertebrates (85% bodies), followed fish (53%), macrophytes (27%) phytoplankton (4%). To meet WFD demands, numerous taxonomy-based indices developed among MS, presenting, however, uncertainties possibly related species biogeography. Recent development different types (trait-based, DNA sequencing predictive modeling) provide more accurate results biomonitoring, but should validated MS before wide application assessments.