Effects of water residence time and light availability on nutrient retention and metabolism: experimental approach on artificial streams

Abstract

The preservation of streams is fundamental to insure several direct and indirect benefits offered to them by humans, called ecosystem services. Several techniques for the recovery of highly human-impacted environments are being used. Knowing the effects of these impacts on the indicators of aquatic ecosystem functioning, such as metabolism and nutrient retention, is fundamental for guiding methodologies and strategies for stream restoration. This project aims to investigate the effects of experimental manipulations of light availability and water residence time on ecosystem processes, focusing on two functional indicators (i.e., stream benthic metabolism and nutrient retention). A series of artificial streams will be used in the experiments at the Experimental Streams Facility of the Catalan Institute for Water Research (ICRA), (Girona, Spain). From the experimental manipulations of light availability and water residence time, the following functional indicators of the streams will be evaluated: reactive soluble phosphate and ammonium uptake capacity of the biofilm, its biomass accrual and the metabolism of the benthic community (gross primary production and ecosystem respiration). Through the use of artificial streams at ICRA and their expertise in the area, it will be possible to evaluate the response of these indicators to light availability and water residence time, aiming to contribute to the improvement of recovery techniques, where nutrient retention is maximized and metabolism is maintained close to natural conditions.