POLLEN INFLUX INTO THE LAURENTIAN GREAT LAKES IS A SIGNIFICANT SOURCE OF CARBON

Pollen deposition is often overlooked as a source of allochthonous carbon and nutrients in lacustrine systems. Although pollen is degradation resistant, it has been shown to provide substantial carbon and nutrient subsidies to communities of aquatic consumers in both saline and freshwater environments. The input of pollen and other allochthonous organic matter (OM) imports to the Laurentian Great Lakes (LGLs) remain a relatively understudied component of the carbon cycle of each lake. As part of the Great Lakes Sediment Surveillance Program, we characterized the chemical composition and source of allochthonous OM across surface sediments of Lakes Superior, Huron, and Ontario. Surface sediments were collected from approximately 30 sites in each lake and analyzed for bulk elemental and stable isotope content as well as lignin-phenol biomarkers using cupric oxide oxidation and gas chromatography-mass spectrometry (GCMS). Lignin-phenol proxy ratios allowed us to trace pollen-derived OM, as pollen is much higher in cinnamyl phenols than other terrestrial OM. These proxies indicated that airborne pollen was a major contributor to offshore sedimentary OM in each lake, while soil and vegetative runoff were major contributors to nearshore sedimentary OM. Previously overlooked aeolian influx of pollen into the LGLs may constitute a significant carbon input, especially in offshore sediments, which in turn has significant potential impacts on our knowledge of carbon and other nutrient sourcing into the LGLs.

Primary Presenter: Kathryn Schreiner, University of Minnesota Duluth (kschrein@d.umn.edu)

Authors:

Jake Zunker, University of Minnesota Duluth  (zunke018@d.umn.edu)

Kathryn Schreiner, University of Minnesota Duluth  (kschrein@d.umn.edu)

Lily Karg, University of Minnesota Duluth  (karg0038@d.umn.edu)

Chan Lan Chun, University of Minnesota Duluth  (chun0157@d.umn.edu)

Christopher Filstrup, University of Minnesota Duluth  (filstrup@d.umn.edu)

Euan Reavie, University of Minnesota Duluth  (ereavie@d.umn.edu)

Bridget Ulrich, University of Minnesota Duluth  (ulrichb@d.umn.edu)