The aim of this paper was to assess the relationships between habitat type, physical and chemical water conditions and the richness of non-arthropod freshwater invertebrate communities (macro and micro species). Our analyses are based on the results from a survey performed in 74 oligotrophic mountain ecosystems (rivers, streams, lakes, lagoons, reservoirs and mires) in the six watersheds included ... [Show full abstract] within the Nature2000 network, located in the northwest of the Iberian Peninsula. We performed a multi-habitat sampling of all freshwater environments (open waters, bentos, mosses and lichens on rocks, tree trunks and submerged leaf litter) to test for patterns of local biodiversity in shallow locations.
The habitat selection of 27 taxa of non-arthropod invertebrates (INA), pertaining to 6 different Phyla, was characterized. Proximity to headwaters, with coarse riverbed lithologies, oligotrophic waters and limited mineralization, create areas of low food availability, which in turn results in poor biotic communities and low productivity. The richest ecosystem was at the Sanabria Lake. The presence of taxa specifically associated with oligosaprobic conditions and low mineralization, endorse their use as indicators of water quality. The existence of invasive species only present in low sections confirms that mountainous areas are the refuge for native biota.