Anoxia decreases the magnitude of the carbon, nitrogen, and phosphorus sink in freshwaters.

Autor: Carey CC; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Hanson PC; Center for Limnology, University of Wisconsin-Madison, Madison, Wisconsin, USA., Thomas RQ; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA.; Department of Forest Resources and Environmental Conservation, Virginia Tech, Blacksburg, Virginia, USA., Gerling AB; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Hounshell AG; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Lewis ASL; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Lofton ME; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., McClure RP; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Wander HL; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Woelmer WM; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Niederlehner BR; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA., Schreiber ME; Department of Geosciences, Virginia Tech, Blacksburg, Virginia, USA.
Jazyk: angličtina
Zdroj: Global change biology [Glob Chang Biol] 2022 Aug; Vol. 28 (16), pp. 4861-4881. Date of Electronic Publication: 2022 May 25.
DOI: 10.1111/gcb.16228
Abstrakt: Oxygen availability is decreasing in many lakes and reservoirs worldwide, raising the urgency for understanding how anoxia (low oxygen) affects coupled biogeochemical cycling, which has major implications for water quality, food webs, and ecosystem functioning. Although the increasing magnitude and prevalence of anoxia has been documented in freshwaters globally, the challenges of disentangling oxygen and temperature responses have hindered assessment of the effects of anoxia on carbon, nitrogen, and phosphorus concentrations, stoichiometry (chemical ratios), and retention in freshwaters. The consequences of anoxia are likely severe and may be irreversible, necessitating ecosystem-scale experimental investigation of decreasing freshwater oxygen availability. To address this gap, we devised and conducted REDOX (the Reservoir Ecosystem Dynamic Oxygenation eXperiment), an unprecedented, 7-year experiment in which we manipulated and modeled bottom-water (hypolimnetic) oxygen availability at the whole-ecosystem scale in a eutrophic reservoir. Seven years of data reveal that anoxia significantly increased hypolimnetic carbon, nitrogen, and phosphorus concentrations and altered elemental stoichiometry by factors of 2-5× relative to oxic periods. Importantly, prolonged summer anoxia increased nitrogen export from the reservoir by six-fold and changed the reservoir from a net sink to a net source of phosphorus and organic carbon downstream. While low oxygen in freshwaters is thought of as a response to land use and climate change, results from REDOX demonstrate that low oxygen can also be a driver of major changes to freshwater biogeochemical cycling, which may serve as an intensifying feedback that increases anoxia in downstream waterbodies. Consequently, as climate and land use change continue to increase the prevalence of anoxia in lakes and reservoirs globally, it is likely that anoxia will have major effects on freshwater carbon, nitrogen, and phosphorus budgets as well as water quality and ecosystem functioning.
(© 2022 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
Externí odkaz: