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COMPARISONS OF ZOOPLANKTON COMMUNITY SIZE STRUCTURE IN THE GREAT LAKES
Citation:
YURISTA, P. M., J. R. KELLY, AND S. E. MILLER. COMPARISONS OF ZOOPLANKTON COMMUNITY SIZE STRUCTURE IN THE GREAT LAKES. C05S08, JOURNAL OF GEOPHYSICAL RESEARCH. American Geophysical Union, Washington, DC, 111(Oceans):1-12, (2006).
Impact/Purpose:
This paper addresses one phase in the evaluation of new technologies for the measurement and detection of zooplankton along with size-based metrics as indicators in the Laurentian Great Lakes.
Description:
Zooplankton mean-size and size-spectra distribution potentially reflect the condition of trophic interactions and ecosystem health because they are affected by both resource availability and planktivore pressure. We assessed zooplankton mean-size and size-spectra using an optical plankton counter (OPC) on thirty five site visits among Lakes Superior, Michigan, Huron, Erie and Ontario (2002-2003). The surveys were conducted in both nearshore regions (5m to 20m depth) and on associated transects to offshore regions either greater than 8 km from shore or greater than 100 m depth. The survey sites were distributed across a gradient of land use disturbance in watersheds adjacent to the nearshore regions. The mean-size, biomass density, statistical size distribution, and normalized biomass size-spectra of zooplankton were determined from OPC measurements for all locations. Among lakes significant differences were observed in mean-size, biomass, and the parameters of size-spectra distributions for both nearshore and offshore regions. Within lakes differences in some parameters were observed that allowed for significant discrimination between nearshore and offshore zooplankton communities in Lakes Michigan, Ontario and Superior. Similarly some parameters allowed for discrimination between offshore epilimnion and hypolimnion waters in Lakes Michigan, Huron, and Ontario. The use of OPC technology and parameters that characterize spectral shape may have potential as an efficient and economic way for developing a zooplankton metric to discriminate among zooplankton communities in the Great Lakes.