Estimating river nutrient concentrations consistent with good ecological condition: More stringent nutrient thresholds needed

Nutrient pollution remains one of the leading causes river degradation, making it important to set thresholds that support good ecological condition, which is main objective managing Europe's aquatic environment. A wide range methods has been used by European member states nutrient in past, and these vary greatly among countries, even for similar types. In some have using expert judgement or statistical distribution concentrations. Application such creates problems planning strategies achieve status transboundary basins. An alternative approach examine relationship between concentration one, more, biological variables. Such relationships can then be inform decisions water managers. We use 'ecology-based' approaches (univariate regression mismatch analyses) derive several types Central Europe. Our analysis focused on soluble reactive phosphorus (SRP) total nitrogen (TN), two variables were responsible significant variation (40–55%) benthic floras. this study, first time, are estimated both macrophytes phytobenthos (EQRs) separately combination, calculated as minimum average EQRs sub-elements. The resulting supporting from 21 42 µg/L SRP 0.9–3.5 mg/L TN low alkalinity lowland type, 32–90 1.0–2.5 mid-altitude type. These targets compared values states. demonstrate national fall within predicted if uncertainty taken into consideration; however, threshold considerably exceed range. Adopting ecology-based should improve sustainable management where nutrients major pressure preventing achievement status.