Report on Harmonisation of freshwater biological methods

Annex VII: WFD classification and intercalibration requirements1. In order to evaluate the biological methods in relation to the WFD requirements,we recall the relevant sections of the Directive and the common agreed interpretationsof these sections.2. In the WFD ecological status of surface waters is defined as ”…an expression ofthe quality of the structure and functioning of aquatic ecosystems associated withsurface waters, classified in accordance with Annex V” (Article 2.21). This impliesthat the classification systems should reflect changes taking place in the structure ofthe biological communities and in the overall ecosystem functioning as response toanthropogenic pressures (e.g. nutrient loading, acidification).3. The WFD, also, stipulates that the ecological quality of water bodies should beclassified into five quality classes (high, good, moderate, poor, and bad) using anEcological Quality Ratio (EQR), defined as the ratio between type specific referenceconditions and observed values of the relevant biological quality elements (Table 1).Guidance on how to establish reference conditions, and on classification of ecologicalstatus was prepared within WFD-CIS working groups REFCOND (Anonymous,2003a) and ECOSTAT (Anonymous, 2004).Table 1. Biological quality elements and metrics required for the classification of the high,good, and moderate ecological quality status of different surface waters according to thenormative definitions described in the Annex V of the WFD. 1 = Taxonomiccomposition, 2 = Abundance, 3= Biomass, 4 = Plankton blooms, 5= diversity, 6=sensitive taxa (e.g. sensitive vs. insensitive species of organisms), 7 = age structure(from Heiskanen et al., 2004).Quality element Rivers LakesPhytoplankton 1, 2, 3*, 4 1, 2, 3, 4Aquatic flora 1, 2 1, 2Benthic invertebrates 1, 2, 5, 6 1, 2, 5, 6Fish 1, 2, 6, 7 1, 2, 6, 7*transparency as a proxy of phytoplankton biomass107