The algal lift: Buoyancy‐mediated sediment transport

The role of benthic algae as biostabilizers of sediments is well‐known, however, their potential to lift and transport sediments remains unclear. Under low‐flow conditions, matured algal mats may detach from the bed and may lift up sediment, thereby causing disturbance to the uppermost streambed sed...

Full description

Saved in:
Bibliographic Details
Published in:Water resources research 2016-01, Vol.52 (1), p.108-118
Main Authors: Mendoza‐Lera, Clara, Federlein, Laura L., Knie, Matthias, Mutz, Michael
Format: Article
Language:English
Subjects:
Algae
Algal mats
Area
benthic‐pelagic coupling
Biological effects
Bubbles
Buoyancy
Detaching
Ecosystem disturbance
Ecosystems
floating algal mats
flume experiments
Flumes
Gravel
Lift
Low flow
Mats
Oxygen
Phytobenthos
Primary production
Sand
Sediment
sediment dynamics
Sediment transport
Sediments
Streambeds
Transport
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The role of benthic algae as biostabilizers of sediments is well‐known, however, their potential to lift and transport sediments remains unclear. Under low‐flow conditions, matured algal mats may detach from the bed and may lift up sediment, thereby causing disturbance to the uppermost streambed sediment. We tested the potential of algal mats to lift sediments in 12 indoor flumes filled with sand (0.2 – 0.8 mm), gravel (2 – 8 mm) or a sand‐gravel mixture (25/75% mass). After four weeks, the algal mats covered about 50% of the flumes area. Due to the accumulation of oxygen gas bubbles in the mats, that developed from high primary production at 4.5 weeks, about half of the algal mats detached from the bed carrying entangled sediments. Both the area covered by algal mats and detached area were similar among sediment types, but the amount of sediment transported tended to be higher for sand and sand‐gravel mixture compared to gravel. Our results reveal that biologically mediated sediment transport mainly depends on the development of a dense filamentous algal matrix, that traps gas bubbles, increasing the mats buoyancy. This novel mechanism of sediment transport will occur in shallow ecosystems during low‐flow periods, with the highest impact for sandy sediments. Key Points: Entangled gas bubbles cause algal mat buoyancy‐mediated lift The potential of algal mats to transport sand and gravel is tested Buoyancy‐mediated algal mat detachment can transport sediment
ISSN:0043-1397
1944-7973
DOI:10.1002/2015WR017315