A new index of water quality assessment in Mediterranean wetlands based on crustacean and insect assemblages:: the case of Catalunya (NE Iberian peninsula)

1. According to the European Water Framework Directive (2000/60/CE) tools are required to evaluate wetland ecological quality. In this context, a biological index to evaluate water quality (QAELS) is proposed for Mediterranean wetlands in Catalunya (NE Iberian peninsula). 2. The study was carried out in 99 shallow lentic ecosystems, situated below 800 in a.s.l. and with a maximum depth of less than 6 m. At each sampling point, a range of water parameters was measured (temperature, conductivity, pH, dissolved oxygen, chlorophyll a, dissolved nutrients and total nutrients) and data were gathered on invertebrate taxon composition (collected with a dip-net of 250 pm mesh size). 3. A previous classification of wetlands in that area was required to obtain QAELS. The QAELS index is obtained by: (1) the relative abundance of each microcrustacean taxon (Cladocera, Copepoda and Ostracoda) weighted by an ecological quality requirement coefficient, which is obtained for each taxon by means of partial canonical correspondence analysis (ACCO index); and (2) the taxonomic richness of crustaceans and aquatic insects (RIC index). 4. Several taxonomic resolutions were also tested in order to determine the simplest identification level that gives acceptable results in further applications of the QAELS index. It is concluded that the composition of microcrustacean assemblages (ACCO index) is useful for assessing the water quality of Mediterranean wetlands. 5. The RIC index improves the relationship of the QAELS index to water quality variables, avoiding possible anomalous values that could be obtained when using the ACCO index alone. Copyright (c) 2005 John Wiley & Sons, Ltd.