Epilithic biomass and metabolism in a north Iberian stream

Abstract:

We studied epilithic biomass and stream metabolism along the Agüera stream (northern Spain) for one year. Epilithon was most abundant in mid-reaches; however, stream metabolism shifted there from autotrophy to heterotrophy during the year. The spatial distribution of epilithon depended mostly on light availability, nutrients and substrate characteristics. Spates were the main source of temporal variation, and resilience of epilithon was controlled by nutrient concentrations. A certain level of disturbance (by sloughing) could be important in maintaining the high capacity of self-purification of this stream.