Comparability of river quality assessment using macrophytes: a multi-step procedure to overcome biogeographical differences.
This paper exposes a new methodological approach to solve the problem of intercalibrating river quality national methods when a common metric is lacking and most of the countries share the same Water Framework Directive (WFD) assessment method. We provide recommendations for similar works in future concerning the assessment of ecological accuracy and highlight the importance of a good common ground to make feasible the scientific work beyond the intercalibration. The approach herein presented was applied to highly seasonal rivers of the Mediterranean Geographical Intercalibration Group for the Biological Quality Element Macrophytes. The Mediterranean Group of river macrophytes involved seven countries and two assessment methods with similar acquisition data and assessment concept: the Macrophyte Biological Index for Rivers (IBMR) for Cyprus, France, Greece, Italy, Portugal and Spain, and the River Macrophyte Index (RMI) for Slovenia. Database included 318 sites of which 78 were considered as benchmarks. The boundary harmonization was performed for common WFD-assessment methods (all countries except Slovenia) using the median of the Good/Moderate and High/Good boundaries of all countries. Then, whenever possible, the Slovenian method, RMI was computed for the entire database. The IBMR was also computed for the Slovenian sites and was regressed against RMI in order to check the relatedness of methods (R(2)=0.45; p<0.00001) and to convert RMI boundaries into the IBMR scale. The boundary bias of RMI was computed using direct comparison of classification and the median boundary values following boundary harmonization. The average absolute class differences after harmonization is 26% and the percentage of classifications differing by half of a quality class is also small (16.4%). This multi-step approach to the intercalibration was endorsed by the WFD Regulatory Committee.
Universidade de Lisboa, Instituto Superior de Agronomia, Centro de Estudos Florestais, Tapada da Ajuda, 1349-017 Lisboa, Portugal. Electronic address: fraguiar@isa.ulisboa.pt.
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Aguiar
Universidade de Lisboa, Instituto Superior de Agronomia, Centro de Estudos Florestais, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
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Segurado
University of Ljubljana, Ljubljana, Slovenia; Institute for Water of the Republic of Slovenia, Ljubljana, Slovenia.
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Urbanič
University of Barcelona, Barcelona, Spain.
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Cambra
IRSTEA, Bordeaux, France.
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Chauvin
ENEA, Saluggia Research Centre, Italy.
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Ciadamidaro
Water Development Department, Ministry of Agriculture, Natural Resources and Environment, Lefkosia, Cyprus.
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Dörflinger
Agência Portuguesa do Ambiente, I.P. (APA), Portugal.
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Ferreira
University of Ljubljana, Ljubljana, Slovenia.
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Germ
Water Development Department, Ministry of Agriculture, Natural Resources and Environment, Lefkosia, Cyprus; University of Patras, Patras, Greece.
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Manolaki
ENEA, Saluggia Research Centre, Italy.
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Minciardi
Catalan Water Agency, Barcelona, Spain.
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Munné
Water Development Department, Ministry of Agriculture, Natural Resources and Environment, Lefkosia, Cyprus; University of Patras, Patras, Greece.
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Papastergiadou
Universidade de Lisboa, Instituto Superior de Agronomia, Centro de Estudos Florestais, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
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Ferreira
D044822:Biodiversity; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D010944:Plants / Q000145:classification*; D045483:Rivers / Q000737:chemistry*; D014876:Water Pollution
Ecological quality; Intercalibration; Macrophytes; Mediterranean; Metrics; Water Framework Directive