Intercalibrating the Italian classification of Ecological Status based on aquatic macro-invertebrates in very large rivers

The report fits the Italian method in use to classify ecological status in very large rivers using benthic macroinvertebrates - ISA - to the completed XGIG rivers' intercalibration exercise, which covered the results obtained for other European Countries. Specifically, our main aim here is to describe the procedure adopted to make Italian class boundaries, specified for the Italian method, comparable to those of other Member States and to the Global Mean View defined during XGIG activities. The ISA is a 'new to intercalibration' method, i.e. it has not been subject to intercalibration towards any other European assessment methods. The method is a component, for very large and/or non wadable rivers of the MacrOper assessment system (Buffagni et al., 2008). As its close relative for wadable rivers, ISA method is officially adopted in Italy for the purpose of Ecological Status classification in very large and not accessible rivers since 2010 (MATTM, 2010). For ISA, this report provides indication on compliance with the WFD normative definitions and presents results of class boundaries comparison after biological metrics have been harmonized. The results here presented follow the overall structure of the Final XGIG report on large rivers intercalibration (Birk et al., 2016). Similarly to the final XGIG report, the present document provides in its first part an overview of the Italian method that includes description of sampling technique, metrics calculation, demonstration of compliance with WFD criteria and feasibility with the completed intercalibration exercise. The second part describes the full process of comparison of the national good-moderate and high-good class boundaries to the Global Mean View resulting from the XGIG exercise, including specifications adopted for the Italian data.