title: Water quality assessment of rivers using diatom metrics across Mediterranean Europe: a methods intercalibration exercise.
abstract: The European Water Framework Directive establishes a framework for the protection of water resources. However, common water management tools demand common understanding of assessment methods, so quality goals are equally met. Intercalibration of methods ensures the comparability of biological elements across similar geographical areas. Many aspects can influence the outcome of intercalibration: data sampling, treatment methods, taxonomic reliability of databases, choice of metrics for ecological quality status classification, and criteria for selecting reference sites. This study describes the potentials and constraints of the intercalibration of indices using diatoms for assessment of Mediterranean rivers. Harmonisation of diatom taxonomy and nomenclature was based on a previous ring test which took place at the European level. Four diatom indices (Indice de Polluosensibilité Spécifique-IPS, Indice Biologique Diatomées-IBD 2007, Intercalibration Common Metric Italy-ICMi and Slovenian Ecological Status assessment system) were intercalibrated using data from six European Mediterranean countries (Cyprus, France, Italy, Portugal, Slovenia and Spain). Boundaries between High/Good and Good/Moderate quality classes were harmonised by means of the Intercalibration Common Metric (ICM). Comparability between countries was assured through boundary bias and class agreement. The national boundaries were adjusted when they deviated more than a quarter of a class equivalent (0.25) from the global mean. All national methods correlated well with the ICM, which was sensitive to water quality (negatively correlated to nutrients). Achnanthidium minutissimum sensu lato was the most discriminative species of Good ecological status class. Planothidium frequentissimum, Gomphonema parvulum and Nitzschia palea were the most contributive to Moderate ecological status class. Some taxa were discriminative for both Good and Moderate ecological status classes due to low indication and ecological discriminative power but also due to differences in taxonomy between countries. This intercalibration exercise allowed establishment of common water quality goals across Mediterranean Europe, which is substantiated with the ICM.
authors.affiliation: Department of Biology, GeoBioSciences GeoTechnologies and GeoEngineering (GeoBioTec) Research Centre, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: salmeida@ua.pt.
authors.forename: Salomé F P
authors.initials: SF
authors.lastname: Almeida
authors.affiliation: Department of Biology, GeoBioSciences GeoTechnologies and GeoEngineering (GeoBioTec) Research Centre, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Carmen
authors.initials: C
authors.lastname: Elias
authors.affiliation: Water Institute, Av. Almirante Gago Coutinho, no. 30, 1049-066 Lisboa, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Ferreira
authors.affiliation: Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technologic Park of the University of Girona, Emili Grahit, 101, E-17003 Girona, Spain; Institute of Aquatic Ecology, University of Girona, Campus de Montivili, 17071 Girona, Spain.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Tornés
authors.affiliation: Italian National Institute of Health (ISS), Environment & Primary Prevention Department, Viale Regina Elena, 299, 00161 Roma, Italy.
authors.forename: Camilla
authors.initials: C
authors.lastname: Puccinelli
authors.affiliation: IRSTEA, 50 avenue de Verdun, 33612 Cestas Gazinet, France.
authors.forename: François
authors.initials: F
authors.lastname: Delmas
authors.affiliation: Water Development Department, 100-110 Kennenty Avenue, Lefkosia, Cyprus.
authors.forename: Gerald
authors.initials: G
authors.lastname: Dörflinger
authors.affiliation: Institute for Water of the Republic of Slovenia, Hajdrihova 28c, 1000 Ljubljana, Slovenia.
authors.forename: Gorazd
authors.initials: G
authors.lastname: Urbanič
authors.affiliation: Italian National Institute of Health (ISS), Environment & Primary Prevention Department, Viale Regina Elena, 299, 00161 Roma, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Marcheggiani
authors.affiliation: IRSTEA, 50 avenue de Verdun, 33612 Cestas Gazinet, France.
authors.forename: Juliette
authors.initials: J
authors.lastname: Rosebery
authors.affiliation: Italian National Institute of Health (ISS), Environment & Primary Prevention Department, Viale Regina Elena, 299, 00161 Roma, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Mancini
authors.affiliation: Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technologic Park of the University of Girona, Emili Grahit, 101, E-17003 Girona, Spain; Institute of Aquatic Ecology, University of Girona, Campus de Montivili, 17071 Girona, Spain.
authors.forename: Sergi
authors.initials: S
authors.lastname: Sabater
mesh_terms: D017377:Diatoms / Q000145:classification* / Q000254:growth & development; D004784:Environmental Monitoring / Q000379:methods*; D019083:Mediterranean Region; D045483:Rivers / Q000737:chemistry*; D014876:Water Pollution / Q000032:analysis / Q000706:statistics & numerical data; D060753:Water Quality / Q000592:standards
keywords: Benthic diatoms; Ecological quality assessment; European Water Framework Directive; Intercalibration; Mediterranean rivers