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Phosphorus enrichment of the oligotrophic River Rede (Northumberland, UK) has no effect on periphyton growth rate

McCall, Stephanie J.; Bowes, Michael J.; Warnaars, Tanya A.; Hale, Michelle S.; Smith, James T.; Warwick, Alan; Barrett, Cyril. 2014 Phosphorus enrichment of the oligotrophic River Rede (Northumberland, UK) has no effect on periphyton growth rate. Inland Waters, 4 (2). 121-132. 10.5268/IW-4.2.692

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Abstract/Summary

Reducing phosphorus (P) loading to rivers is seen as a key mitigation measure to improve aquatic ecology and control excessive algal growth, as P is widely assumed to be the limiting nutrient in most rivers. Nutrient enrichment experiments using within-river flume mesocosms were conducted in the oligotrophic River Rede, to determine how periphyton accrual was affected by increasing P concentrations. Increasing the soluble reactive phosphorus (SRP) concentration from the ambient concentration of 15 µg L-1 to concentrations ranging from 30 µg L-1 to 130 µg L-1 had no significant effect of periphyton growth rate, demonstrating that the periphyton was not P limited, even in this nutrient poor river. However, at SRP concentrations greater than 100 µg L-1, diatom communities shifted to species that were more tolerant of higher nutrient concentrations. Elemental analysis showed that there was a positive linear relationship between biofilm P content and the SRP concentration in the overlying water. This ability to store P suggests that periphyton growth is being limited by a secondary factor (such as nitrogen (N)) and may provide a mechanism by which future periodic increases in N concentration may stimulate periphyton growth. Flow velocity, light, and invertebrate grazing pressure also have important roles in controlling periphyton biomass in the River Rede.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5268/IW-4.2.692
Programmes: CEH Topics & Objectives 2009 - 2012 > Water
CEH Sections: Boorman (to September 2014)
Acreman
Reynard
ISSN: 2044-2041
Additional Keywords: algae, biofilm, eutrophication, flume mesocosms, phosphorus limitation
NORA Subject Terms: Ecology and Environment
Date made live: 14 May 2014 13:22 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/505434

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