Temperature dependence of stream benthic respiration in an Alpine river network under global warming

Abstract

Summary 1. Global warming has increased the mean surface temperature of the Earth by 0.6 °C in the past century, and temperature is probably to increase by an additional 3 °C by 2100. Water temperature has also increased, which in turn can affect metabolic rate in rivers. Such an increase in metabolic rate could alter the role of river networks in the global C cycle, because the fraction of allochthonous organic C that is respired may increase. 2. Laboratory‐based incubations at increasing water temperature were used to estimate the temperature dependence of benthic respiration in streams. These experiments were performed on stones taken from seven reaches with different thermal conditions (mean temperature ranging 8–19 °C) within the pre‐alpine Thur River network in Switzerland, June–October 2007. 3. The activation energy of respiration in different reaches along the river network (0.53 ± 0.12 eV, n = 94) was similar, indicating that respiration was constrained by the activation energy of the respiratory complex (E = 0.62 eV). Water temperature and the thickness of the benthic biofilm influence the temperature dependence of respiration and our results suggest that an increase of 2.5 °C will increase river respiration by an average of 20 ± 1.6%.

Climate change and freshwater ecosystems: impacts across multiple levels of organization

“…Castella et al 2001;Johnson & Miyanishi 2008). Nevertheless, if used carefully, such approaches can provide answers to important parts of the puzzle that cannot be addressed by experiments, which inevitably fail to capture the full complexity of natural systems or to allow for local adaptation (but see Acuna et al 2008).…”

Bacterial structures and ecosystem functions in glaciated floodplains: contemporary states and potential future shifts

“…Heterotrophic bacteria are crucial in the functional ecology of aquatic ecosystems, being the driving force behind metabolic processes like respiration and productivity, nutrient cycling and fluxes, trophic links with secondary consumers and numerous biogeochemical processes (Edwards et al, 1990;Kirchman, 1994;Hall and Meyer, 1998;Acuna et al, 2008). The hyporheic zone and its heterotrophic components have an important role by integrating many of these ecosystem functions (EFs) at the interface between surface waters, groundwaters and the riparian zone (Hendricks, 1993;Stanford and Ward, 1993;Findlay, 1995;Battin, 1999).…”

Ultrahigh bacterial production in a eutrophic subtropical Australian river: Does viral lysis short‐circuit the microbial loop?

“…With climate change causing increases in global freshwater temperatures (Koeve and Ducklow 2001;Acuna et al 2008), there is a widening gap in our knowledge of the effect of freshwater bacterial activity in warmer climates. This information is vital to predict future trends in global CO 2 budgets, as increases in bacterial production are inversely related to latitude and hence directly related to increasing global temperature.…”

“…This information is vital to predict future trends in global CO 2 budgets, as increases in bacterial production are inversely related to latitude and hence directly related to increasing global temperature. Increases in bacterial activity and changes in its fate could alter the role of rivers in the global carbon cycle, with an increase in the amount of allochthonous DOC that is respired (Acuna et al 2008). Here, we intend to follow biodegradable DOC inputs into a subtropical river by comparing heterotrophic bacterial production and carbon demand to the rates of primary production, with a view to describing potential pathways for DOC and bacterial production loss from the ecosystem.…”