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Stream drying drives microbial ammonia oxidation and first-flush nitrate export.

  • Merbt SN Eawag-Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Überlandstrasse 133 Postfach 611, 8600, Dübendorf, Switzerland.
  • Proia L Catalan Institute for Water Research, Emili Grahit 101, 17003, Girona, Spain.
  • Prosser JI Institute of Biological and Environmental Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive, Aberdeen, AB24 3UU, United Kingdom.
  • Martí E Integrative Freshwater Ecology Group, Centre d'Estudis Avançats de Blanes, CEAB-CSIC, Accés a la Cala St. Francesc 14, 17300, Blanes, Spain.
  • Casamayor EO Integrative Freshwater Ecology Group, Centre d'Estudis Avançats de Blanes, CEAB-CSIC, Accés a la Cala St. Francesc 14, 17300, Blanes, Spain.
  • von Schiller D Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country, PO Box 644, 48080, Bilbao, Spain.
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  • 2016-11-19
Published in:
  • Ecology. - 2016
ammonia oxidation
ammonia oxidizing archaea (AOA)
ammonia oxidizing bacteria (AOB)
dry riverbed
intermittent flow
nitrification
semiarid ecosystems
stream
Ammonia
Archaea
Ecology
Nitrification
Nitrogen Cycle
Oxidation-Reduction
Phylogeny
Rivers
Soil Microbiology
Spain
Water Microbiology
English Stream microbial communities and associated processes are influenced by environmental fluctuations that may ultimately dictate nutrient export. Discharge fluctuations caused by intermittent stream flow are increasing worldwide in response to global change. We examined the impact of flow cessation and drying on in-stream nitrogen cycling. We determined archaeal (AOA) and bacterial ammonia oxidizer (AOB) abundance and ammonia oxidation activity in surface and deep sediments from different sites along the Fuirosos stream (Spain) subjected to contrasting hydrological conditions (i.e., running water, isolated pools, and dry streambeds). AOA were more abundant than AOB, with no major changes across hydrological conditions or sediment layers. However, ammonia oxidation activity and sediment nitrate content increased with the degree of stream drying, especially in surface sediments. Upscaling of our results shows that ammonia oxidation in dry streambeds can contribute considerably (~50%) to the high nitrate export typically observed in intermittent streams during first-flush events following flow reconnection. Our study illustrates how the dry channels of intermittent streams can be potential hotspots of ammonia oxidation. Consequently, shifts in the duration, spatial extent and severity of intermittent flow can play a decisive role in shaping nitrogen cycling and export along fluvial networks in response to global change.
Language
  • English
Open access status
green
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Persistent URL
https://folia.unifr.ch/global/documents/272795
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