Assessing the responses of aquatic macrophytes to the application of a lanthanum modified bentonite clay, at Loch Flemington, Scotland, UK

• Published in: Hydrobiologia 2014-10, Vol.737 (1), p.309-320
• Main Authors: Gunn, Iain D. M, Meis, Sebastian, Maberly, Stephen C, Spears, Bryan M
• Format: Article
• Language: English
• Subjects: Aquatic plants; Bentonite; Biomedical and Life Sciences; Clay; Ecology; Elodea canadensis; Environmental restoration; Eutrophication; Freshwater & Marine Ecology; invasive species; Lake beds; Lake renewal; Lake restoration; Lakes; Lanthanum; Life Sciences; macrophytes; phosphorus; Plants in Hydrosystems; Rare earth metals; Rare species; sediments; Sediments (Geology); species diversity; Species richness; Submerged plants; Trophic status; vegetation; Water depth; Water quality; Zoology
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-013-1765-5

Loch Flemington is a shallow lake of international conservation and scientific importance. In recent decades, its status has declined as a result of eutrophication and the establishment of non-native invasive aquatic macrophytes. As previous research had identified the lake bed sediments as an important source of phosphorus (P), the P-capping material Phoslock® was applied to improve water quality. This article documents the responses of the aquatic macrophyte community by comparing data collected between 1988 and 2011. Summer water-column total P concentrations decreased significantly and water clarity increased following treatment. Aquatic plant colonisation depth increased and plant coverage of the lake bed extended. However, the submerged vegetation remained dominated by the non-native Elodea canadensis Michx. Aquatic macrophyte community metrics indicated no significant change in trophic status. Species richness and the number of ‘natural’ eutrophic characteristic species remained broadly similar with no records of rare species of conservation interest. Loch Flemington is still classified as being in ‘unfavourable no change’ condition based on its aquatic macrophytes despite the water quality improvements. The implications of these results are discussed in relation to the future management of Loch Flemington and in the wider context of trying to improve our understanding of lake restoration processes.