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Stability in Lake Superior’s zooplankton community: Results from CSMI surveys 2006-2016
Citation:
Pawlowski, M., M. Sierszen, E. Hinchey, J. Watkins, P. Yurista, J. Kelly, AND J. Scharold. Stability in Lake Superior’s zooplankton community: Results from CSMI surveys 2006-2016. State of Lake Superior Conference, Houghton, MI, October 09 - 12, 2018.
Impact/Purpose:
Zooplankton communities in some of the Great Lakes have undergone changes in recent decades. Compared to the other Great Lakes, the zooplankton community in Lake Superior has been more stable. However, most zooplankton surveys and research in the Great Lakes is done in deep, offshore waters. Under the Cooperative Science Monitoring Initiative (CSMI), probability-based whole lake zooplankton surveys were completed on Lake Superior in 2006, 2011, and 2016. These lakewide surveys suggest that zooplankton communities are stable throughout the lake and provide valuable lakewide data against which future changes in the zooplankton community can be identified.
Description:
Probabilistic, whole-lake zooplankton surveys of Lake Superior were completed in 2006, 2011, and 2016 under the Cooperative Science Monitoring Initiative (CSMI). Zooplankton community structure and biomass in Lake Superior differ by depth, so sampling locations in these surveys were depth-stratified (100m) and both whole-column and epilimnetic zooplankton tows were collected at each station. Results show that zooplankton biomass has been stable within each depth strata since 2006. These results are similar to those from GLNPO’s annual summer survey. However, zooplankton are not sampled in areas shallower than 90m during annual GLNPO surveys and the literature lacks recent information about zooplankton in these shallow areas of Lake Superior. Our results show that zooplankton density and biomass were highly variable within and between years at stations shallower than 30m. Because the CSMI surveys sampled relatively few stations in this stratum, the ability of CSMI surveys to detect changes in zooplankton communities in these shallow areas may be reduced. Therefore, we recommend that future Lake Superior CSMI surveys add or reallocate sites to the underrepresented nearshore areas of the lake. This might improve the ability of CSMI surveys to detect potential zooplankton community changes throughout the lake.