Benthic cyanobacterial assemblages as indicators of nutrient enrichment regimes in a Spanish river

Abstract

The relationships between cyanobacterial abundance and the physical and chemical characteristics of waters were studied to identify the environmental variables responsible for the changes in species composition observed in a river characterized by variations in water quality. Principal component analysis showed that some communities had significantly different species composition and relationships with environmental variables than others. These analyses allowed us to identify indicator species with contrasting responses to nutrient conditions. One of the four cyanobacterial groups distinguished in the analysis was negatively correlated with variables related to aspects of water disturbance, including nutrients. The results indicate that the eutrophication gradient structured species composition and affected cyanobacterial community distribution. Since organisms have an integrating response to their environment, the use of cyanobacterial assemblages to indicate eutrophication gradients could help in the assessment of water quality in aquatic ecosystems.