Ackerman, J. D.. University of Northern British Columbia, 250-960-5539
Loewen, M. R.. University of Toronto, 416-978-7753
Hamblin, P. H.. Canada Centre for Inland Waters,

We conducted a series of cruises over an isolated zebra mussel reef (7 - 11 m depth) in Western Lake Erie, during which we sampled the water column at five depths, to examine the impacts of zebra mussels on the offshore environment. Our analyses included: inorganic seston, organic seston, and chlorophyll a concentration, a flow chamber to examine the ability of zebra mussels to clear seston from water, and an instrumentation package to examine the mixing within the water column. Spatial analysis of seston revealed a statistically significant mussel-feeding signature in chlorophyll a and organic seston within 2 m of the reef. A concentration boundary layer was noted both on and off of the reef. Zebra mussels could remove up to 40% of the total seston in the lab, but the depletion in the field is governed by the dynamics of the concentration boundary layer. Our ability to detect significant impacts of zebra mussels is due to reduced vertical mixing as a result of stratification, refiltration of bottom water, and in situ clearance rates that are lower than those observed in the laboratory. We question whether benthic grazers in offshore environments have a major impact on the water column.
Day: Wednesday, Feb. 3
Time: 09:30 - 09:45am
Location: Eldorado Hotel
Code: SS03WE0930E