Impacts of water level on metabolism and transient storage in vegetated lowland rivers: Insights from a mesocosm study

Marie J. Kurz, Jennifer D. Drummond, Eugènia Martí, Jay P. Zarnetske, Joseph Lee-Cullin, Megan J. Klaar, Silvia Folegot, Toralf Keller, Adam S. Ward, Jan H. Fleckenstein, Thibault Datry, David Hannah, Stefan Krause

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
128 Downloads (Pure)

Abstract

Transient storage zones for water represent potential hot spots for metabolic activity in streams. In lowland rivers, the high abundance of submerged vegetation can increase water transient storage, bioreactive surface areas, and, ultimately, in-stream metabolic activity. Changes in flow resulting from climatic and anthropogenic factors that influence the presence of aquatic vegetation can also, thereby, impact in-stream metabolism and nutrient cycling. We investigated the effects of water column depth on aquatic vegetation cover and its implications on water transient storage and associated metabolic activity in stream mesocosms (n = 8) that represent typical conditions of lowland streams. Continuous injections of metabolically reactive (resazurin-resorufin) tracers were conducted and used to quantify hydraulic transport and whole-mesocosm aerobic respiration. Acetate, a labile carbon source, was added during a second stage of the tracer injection to investigate metabolic responses. We observed both higher vegetation coverage and resazurin uptake velocity, used as a proxy of mesocosm respiration, with increasing water column depth. The acetate injection had a slight, positive effect on metabolic activity. A hydrodynamic model estimated the water transport and retention characteristics and first-order reactivity for three mesocosms. These results suggest that both the vegetated surface water and sediments contribute to metabolically active transient storage within the mesocosms, with vegetation having a greater influence on ecosystem respiration. Our findings suggest that climate and external factors that affect flow and submerged vegetation of lowland rivers will result in changes in stream respiration dynamics and that submerged vegetation is a particularly important and sensitive location for stream respiration.
Original languageEnglish
Pages (from-to)628-644
Number of pages17
JournalJournal of Geophysical Research: Biogeosciences
Volume122
Issue number3
Early online date2 Mar 2017
DOIs
Publication statusPublished - 20 Mar 2017

Keywords

  • ecosystem respiration
  • lowland rivers
  • metabolism
  • resazurin
  • transient storage
  • vegetation

ASJC Scopus subject areas

  • Geophysics
  • Oceanography
  • Forestry
  • Ecology
  • Aquatic Science
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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