Global change is altering the hydrological regime of streams worldwide, which can affect the structure and function of these ecosystems with dramatic consequences for the natural environment and human well-being. We used mesocosms to explore how changes in water flow velocity alter the biomass (as ash-free dry mass [AFDM] and chlorophyll-A [Chla]) and metabolic activity (as gross primary production [GPP] and ecosystem respiration [ER]) of periphytic biofilms. We grew periphyton on tiles in 8 indoor experimental channels under constant nutrient concentration and light availability. Initial flow velocity (0.1 m/s) was either increased to 0.25 m/s (high flows) or decreased to 0.05 m/s (low flows) for 26 days. AFDM increased by 1.7 times under low flows compared to initial conditions, while there were no significant changes in Chla. Moreover, low flows induced decreases in ER, and especially GPP. We attributed this decrease in photoautotrophic activity to the shading effect caused by the accumulation of fine benthic organic matter on the top of the periphyton. In contrast, at high flows, AFDM did not change, while GPP substantially increased, likely because higher flows induced higher nutrient uptake rates. Our results show that changes in flow velocity can strongly influence periphyton structure and function, which can have further consequences for stream productivity and gas emissions. The implications of our results will be discussed in light of the marked hydrological seasonality of Mediterranean streams.
Primary Presenter: Carolina Jativa, Center for Advances Studies of Blanes (CEAB - CSIC) (carito.jativa@gmail.com)
Authors:
Carolina Jativa, CEAB-CSIC (carito.jativa@gmail.com)
Flavia Trombon, University of Koblenz-Landau (flavia.tromboni@gmail.com)
Alain Maasri, Leibniz-Institute of Freshwater Ecology and Inland Fisheries ()
Silvia Mohr, (silvia.mohr@uba.de)
Anna Lupon, CEAB-CSIC (anna.lupon@gmail.com)
Susana Bernal, CEAB-CSIC (sbernal@ceab.csic.es)
Changes in flow velocity impact stream periphyton metabolic activity: a mesocosms approach
Category
Scientific Sessions > SS046 Mesocosm Based Experimental Studies to Address Challenges Emerging From Global Change on Stability of Aquatic Ecosystems
Description
Time: 06:30 PM
Date: 6/6/2023
Room: Mezzanine