Propuesta de un índice de vegetation acuática (IVAM) para la evaluación del estado trófico de los ríos de Castilla-La Mancha: Comparación con otros índices bióticos

Abstract

The Water Framework Directive proposes the evaluation of the ecological status through biological indicators, among them the aquatic flora. In order to do that, as a novelty in a European context, a new trophic index for aquatic vegetation at the genus taxonomic resolution was created, that also includes diverse aquatic autotrophic groups. The index is called IVAM (Macroscopic Aquatic Vegetation Index), and takes into account macrophytes as well as macrophytes, including briophytes, pteridophytes, algae and phanerogams, as long as they are macroscopic life forms distinguishable to the naked eye. Two versions are presented according to taxonomic resolution: IVAM-G (genus) and IVAM-B (low taxonomic resolution).Thus, from 141 samples of aquatic vegetation collected in 106 stream stretches during the years 2001-2003 (basins of the rivers Tajo, Guadiana, Júcar, Segura, and Guadalquivir), and the phosphate and ammonium concentrations measured, tolerance scores and ecological breath were calculated for the collected taxa. The IVAM-G version showed a higher response to eutrophication versus other quality indices (IVAM-B, IM) and similar or even better response to other aquatic vegetation trophic indices at the species level of taxonomic resolution (GIS, MTR) used in other European countries. This indicates a clear advantage in using the IVAM for river's trophic status evaluation, when compared to other indices that require both a high effort (time and cost) and a higher level of specialisation. © Asociación Española de Limnología.