Resuspension created by bedload transport of macroalgae: implications for ecosystem functioning

Paula Canal-Vergés, M. Vedel, T. Valdemarsen, E. Kristensen, M. R. Flindt

Research output: Contribution to journalJournal articleResearchpeer-review


Previous studies suggest that current-driven plant transport in shallow lagoons and estuaries is associated with increased turbidity. Our hypothesis is therefore that macroalgae erode surface sediment while drifting as bedload. This ballistic effect of moving plants on surface sediment was tested in a series of controlled annular flume experiments, where simultaneous measurements of macrophytes transport and turbidity were conducted at increasing current velocities. Sediment erosion always started earlier in experiments with plants than in control experiments without plants. Turbidity increased immediately when plants started to move at current velocities of 2-4 cm s(-1). From a background concentration of 7-10 mg SPM l(-1), turbidity increased to 30-50 mg SPM l(-1) for Ceramium sp., Ulva lactuca and Chaetomorpha linum, while the more rigid Gracilaria sp., caused much higher turbidities (50-180 mg SPM l(-1)). Such plant induced sediment erosion at low current velocity can explain the observed appearance of turbid waters in estuaries and lagoons in the absence of strong wind and wave action. Based on 3-D hydrodynamic modelling, it was determined that plant driven erosion occurs during most of the growth season in a shallow eutrophic estuary (Odense Fjord, Denmark).
Original languageEnglish
Issue number1
Pages (from-to)69-76
Publication statusPublished - 2010
Externally publishedYes


  • Aquatic Science
  • Ballistic effect
  • Erosion threshold
  • Light
  • Macroalgae
  • Sediment stability
  • Turbidity
  • Annular flume
  • Background concentration
  • Bed load
  • Bed-load transport
  • Current velocity
  • Current-driven
  • Denmark
  • Ecosystem functioning
  • Erosion thresholds
  • Gracilaria
  • Growth season
  • Hydrodynamic modelling
  • In-control
  • Low currents
  • Macro-algae
  • Macrophytes
  • Re-suspension
  • Sediment erosion
  • Simultaneous measurement
  • Strong winds
  • Surface sediments
  • Turbid water
  • Wave actions
  • Ballistics
  • Estuaries
  • Experiments
  • Sedimentology
  • Three dimensional
  • bedload
  • coastal lagoon
  • current velocity
  • ecosystem function
  • erosion rate
  • eutrophic environment
  • flume experiment
  • green alga
  • growing season
  • hydrodynamics
  • light effect
  • macroalga
  • macrophyte
  • resuspension
  • sediment transport
  • suspended particulate matter
  • three-dimensional modeling
  • threshold
  • turbidity
  • wave action
  • Fyn
  • Odense Fjord
  • Syddanmark
  • Ceramium
  • Chaetomorpha linum
  • Gracilaria sp.
  • Ulva
  • Ulva lactuca
  • bedload transport
  • ecosystem functioning
  • macrophyte transport
  • sediment stability
  • Algae Plantae (Algae, Microorganisms, Nonvascular Plants, Plants) - Chlorophyta [13300] Ulva lactuca species Chaetomorpha linum species
  • Algae Plantae (Algae, Microorganisms, Nonvascular Plants, Plants) - Rhodophyta [14700] Gracilaria sp. genus Ceramium sp. genus
  • 07502, Ecology: environmental biology - General and methods
  • 07506, Ecology: environmental biology - Plant
  • Environmental Sciences
  • Ecology

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