Aquatic Sciences Meeting, Albuquerque 2001

SS01 Submerged Aquatic Vegetation and the Water Column (Environmental Connections)

Date: Tuesday, February 13, 2001, Time: 10:45:00 AM

Location: Galisteo

Bayley, S, E, University of Alberta, Edmonton, Canada, s.bayley@ualberta.ca

Prather, C, , University of Alberta, Edmonton, Canada,

CONTROLS ON SUBMERSED AQUATIC PLANTS (SAV) AND CHLOROPHYLL A IN SHALLOW LAKES IN THE WESTERN BOREAL FOREST (WBF)

Shallow lakes (< 2m) in the WBF have naturally high concentrations of TP in surface waters. Some lakes appear to be dominated by SAV, while others are dominated by dense phytoplankton blooms (and little SAV). This finding is consistent with the concept of alternative stable states whereby shallow lakes (with intermediate to high loadings of TP) develop stable states characterized either by abundant SAV and clear water or by dense phytoplankton blooms and turbid water. These alternative states may be controlled by nutrients (bottom-up control) or top-down control by predatory fish, invertebrates or by climatic events. Multivariate analysis of water chemistry, chl a and SAV abundance from 82 lakes divides the lakes into four main categories: 1)lakes that have low SAV abundance and high algal abundance (chl a=52 ug/l & TP concentrations 168ug/l); 2)lakes that have high SAV abundance and low algae (6ug/l; TP 64ug/l); 3)lakes that have low algae and low SAV; 4)lakes with high algal and high SAV. Current studies are attempting to separate physical parameters from trophic structure to better understand controls on SAV and algae.

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Aquatic Sciences Meeting, Albuquerque 2001

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