SS3.02 Turbulence and Plankton Dynamics
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
WalksDJ, Department of Zoology, University of Toronto, Toronto, Canada, dwalks@zoo.utoronto.ca
Cyr, H, , Department of Zoology, University of Toronto, Toronto, CANADA, helene@zoo.utoronto.ca
 
DOES IT MAKE SENSE TO USE LEOPOLD'S WATER RESIDENCE TIME EQUATION FOR RIVER PLANKTON?
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River zooplankton communities are thought to be structured through advective loss processes as determined by water residence time = ((Drainage Area^0.6)x 0.08)/(Flow Discharge^0.1). Faster flushing rates should reduce the presence of slower-growing planktonic organisms in rivers, resulting in smaller mean body sizes in short water residence time systems. I tested whether mean body size of zooplankton and zooplankton biomass increased with longer residence times in rivers. Crustacean zooplankton body size in rivers decreased with water residence time (P=0.02, R2=0.3, n=17, WRT 0.14-112 days). Zooplankton biomass did not increase with water residence time (P=0.4, n=51), and this relationship did not improve after controlling for the weak effect of Chl a on zooplankton biomass (Chl a effect P=0.06). In using average flow conditions rather than considering the heterogeneity of river currents we may be missing the boat on what actually structures riverine plankton communities.