Surface Water Quality Indicators: Benthic macroinvertebrates in rivers (2020)

Water quality can be valued through the biological communities they host. These communities are altered by human activity and the pollution associated with such activity. The study of the flora and fauna found in an aquatic ecosystem, against the expected fauna and flora, allows to measure the situation of the ecosystem with respect to pollution. The biological indicators selected are derived from the study of the biological quality elements foreseen in the ecological status assessment in the Water Framework Directive 2000/60/EC (WFD) and the indices selected for each type in the RDSE, since these are information periodically studied by means of standardised analyses that allow the collection of annual and quality data. In the case of inland surface waters rivers, the indicator will be configured from the data of benthic phytobents and macroinvertebrates, evaluated according to the provisions of the RDSE for each typology. In the case of both taxonomic groups, it is contemplated the use of different indices according to the type of river in which it is studied. Despite their different approaches, the expected indices evaluate the situation of the river against a pressure, scoring each taxon found according to its ability to tolerate it. The greater the taxonomic diversity of the section to be studied and there are more pressure-intolerant taxa, the better the environmental situation. In order to produce the situation graphs on benthic macroinvertebrates, it has been taken into account whether the indices applied to the analyses of benthic macroinvertebrates exceed the limit established in the RDSE between good and moderate state for each river typology, or do not exceed it. In addition, the typologies without established legal limit have been registered as “No Valuation”.