Caracterización limnológica de la red de embalses del Consorcio de Aguas Bilbao Bizkaia

Abstract

This study carried out a limnological characterization of the eight main water supplying reservoirs managed by the Bilbao Biscay Water Consortium. Considering the 2017–2023 period, environmental variables were analyzed in categories of ionic composition, hydromorphological variables, main nutrients, and trophic status. Phytoplankton communities were also assessed, with a particular focus on cyanobacteria. Differences between reservoirs were identified in terms of ionic composition, morphometric characteristics, and water management. However, essential nutrient concentrations and indicators of algal development showed no relevant differences between reservoirs, with all cases reporting oligotrophic conditions. While phytoplankton communities showed similarities, species biovolume grouped by taxonomic and functional categories highlighted the patterns of ecological succession. Additionally, ungrouped taxa revealed differences between communities in reservoirs within the northern basin (Ibaizabal-Nervión Hydrological Unit) and those in the Mediterranean basin (Zadorra System). These distinctions were further emphasized when considering only cyanobacteria, as this group showed species with specific distributions across geographic groups. This work represents the most detailed ecological description for these reservoirs to the best of our knowledge, contributing to the optimization of the local environmental monitoring network and to the harmonization of criteria for future monitoring efforts.