Impacts of phosphorus concentration and light intensity on river periphyton biomass and community structure

McCall, Stephanie J.; Hale, Michelle S.; Smith, James T.; Read, Daniel S. ORCID:; Bowes, Michael J. ORCID: 2017 Impacts of phosphorus concentration and light intensity on river periphyton biomass and community structure. Hydrobiologia, 792 (1). 315-330.

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Periphyton growth rate has been identified as the key process that leads to river eutrophication. Effort has focused on reducing phosphorus concentrations to control periphyton biomass, but other factors, such as light, are also important. Within-stream flume mesocosms were deployed in the River Lambourn, UK, to investigate how light intensity and phosphorus concentrations affect periphyton biomass and community structure. Soluble reactive phosphorus (SRP) concentrations were tripled in some flumes, and decreased in others by dosing of FeCl3. Increasing SRP concentrations from the ambient concentration of 49 µg L-1 to 155 µg L-1 had no effect on biomass, but community composition (by flow cytometry) shifted from diatom to cyanobacterial dominance. Reducing light levels (equivalent to riparian tree shading) decreased biomass by 40 %, showing that the biofilms were light limited at SRP concentration ≥ 49 µg L-1. Periphyton were phosphorus / light co-limited when SRP concentrations were reduced to 33 µg L-1. Further reductions in SRP concentration (23 µg L-1) resulted in phosphorus limitation of periphyton biomass and increased dominance of diatoms and chlorophytes within the biofilm. Reducing light intensity through providing riparian tree shading could be an important management tool to reduce periphyton biomass and improve ecological status.

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Acreman
Rees (from October 2014)
ISSN: 0018-8158
Additional Information. Not used in RCUK Gateway to Research.: The Related URL link provides a read-only full text copy of the paper.
Additional Keywords: eutrophication, phosphorus-threshold, algal biofilms, flow cytometry, trophic diatom index, multiple stressors
NORA Subject Terms: Ecology and Environment
Related URLs:
Date made live: 13 Feb 2017 11:33 +0 (UTC)

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