The significance of sea ice algae in the Pacific Arctic determined by highly branched isoprenoid biomarkers ...

• Main Author: Koch, Chelsea Wegner
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Digital Repository at the University of Maryland 2021
• Subjects: Biological oceanography; Biogeochemistry; Ecology; FOS Biological sciences; Arctic; benthic invertebrates; biomarkers; diatoms; sea ice; sea ice algae; Chukchi Sea; Pacific; Chukchi; ice algae; Pacific Arctic; Sea ice
• Online Access: https://dx.doi.org/10.13016/jtti-zi4e; https://drum.lib.umd.edu/handle/1903/27315

Our current understanding of ice algae as a carbon source at the base of the Arctic food web is limited because of difficulties unequivocally distinguishing sympagic (sea ice) from pelagic primary production once assimilated by consumers. For this study, I tested the utility of highly branched isoprenoids (HBI), which are unusual lipids produced by diatoms. This includes a biomarker found exclusively in Arctic sea ice termed the ice proxy with 25-carbon atoms (IP25) and two other HBIs with sea ice and pelagic sources. HBI measurements in the Pacific Arctic (the northern Bering and Chukchi seas) were sparse compared to the rest of the Arctic prior to this investigation. Analysis of surface sediments and cores collected across the continental shelf revealed a latitudinal gradient of increasing sympagic HBIs. Some of the highest concentrations of IP25 recorded in the Arctic were found in the Chukchi Sea. Fluxes of IP25 indicated year-round export of ice algal lipids in this region. Persistent diatom fluxes and ...