Abstract
Variable weather patterns during the early months of 2014 and 2015 resulted in differences between years in spring and summer surface water temperatures in the offshore areas of western Lake Superior. Zooplankton were collected in western Lake Superior during several cruises from late spring to early fall in 2014 and 2015 to test the hypotheses that colder summer water temperatures in 2014 were correlated with reduced zooplankton biomass, later peaks in zooplankton biomass, and a smaller contribution of warm-water taxa to the zooplankton assemblage. The total amount of zooplankton biomass from early June through early October did not differ greatly between years. Of the taxonomic subcategories (large-bodied calanoids, small-bodied calanoids, cyclopoids, nauplii, and herbivorous cladocerans) however, cyclopoid and cladoceran biomass was somewhat smaller in 2014 compared to 2015, providing some support for the hypothesis that warm-water taxa contribute less to offshore zooplankton biomass in colder years. The timing of peak biomass for cladocerans, small-bodied calanoids, and cyclopoids did not differ between years, but peaks in the biomass of copepod nauplii and large-bodied calanoids (primarily Limnocalanus macrurus) occurred several weeks later in 2014 than 2015 which was evidence for phenological delay during a year with unusually cold spring and summer surface water temperatures. Though this study only evaluates the role of temperature in driving zooplankton biomass and phenology in Lake Superior, it does provide insight into the potential effects of climate variability on the Lake Superior food web.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 788-797 |
| Number of pages | 10 |
| Journal | Journal of Great Lakes Research |
| Volume | 44 |
| Issue number | 4 |
| DOIs | |
| State | Published - Aug 2018 |
Bibliographical note
Funding Information:We thank Ian Harding, Mike Sorensen, Emily Heald, Trevor Keyler, and the Crew of R / V Blue Heron for assistance with sample collection. Jay Austin and Liz Austin-Minor happily provided sampling equipment and temperature data. We are also grateful to Cory Goldsworthy (Minnesota DNR) for the opportunity to collect additional samples during August of 2014 and to Ted Ozersky, John Pastor, and Nathan Pollesch, who provided helpful comments during the analysis and writing process. This research was part of a larger research effort funded by the Minnesota Environment and Natural Resources Trust Fund (grantee award: M.L. 2013 , Ch52 , Sec 2 , Subd05f ). The Integrated Bioscience Graduate Program at the University of Minnesota Duluth provided additional funding to M. Pawlowski to support the completion of this work.
Funding Information:
We thank Ian Harding, Mike Sorensen, Emily Heald, Trevor Keyler, and the Crew of R/V Blue Heron for assistance with sample collection. Jay Austin and Liz Austin-Minor happily provided sampling equipment and temperature data. We are also grateful to Cory Goldsworthy (Minnesota DNR) for the opportunity to collect additional samples during August of 2014 and to Ted Ozersky, John Pastor, and Nathan Pollesch, who provided helpful comments during the analysis and writing process. This research was part of a larger research effort funded by the Minnesota Environment and Natural Resources Trust Fund (grantee award: M.L. 2013, Ch52, Sec 2, Subd05f). The Integrated Bioscience Graduate Program at the University of Minnesota Duluth provided additional funding to M. Pawlowski to support the completion of this work.
Publisher Copyright:
© 2018 International Association for Great Lakes Research.
Keywords
- Climate change response
- Lake Superior
- Limnocalanus macrurus
- Phenology
- Zooplankton