A Comprehensive Evaluation of C 25 Highly Branched Isoprenoid Alkenes of Marine Diatoms as Proxies for Sea Ice Extent in the Arctic Ocean

• Main Author: Muniak, Tetiana
• Format: Text
• Language: unknown
• Published: ODU Digital Commons 2014
• Subjects: Sea ice; Arctic Ocean; Carbon content; Isopentenoids; Alkenes; Biogeochemistry; Oceanography; Paleontology; Terrestrial and Aquatic Ecology; Arctic; Chukchi
• Online Access: https://digitalcommons.odu.edu/oeas_etds/265; https://doi.org/10.25777/sehg-mk31; https://digitalcommons.odu.edu/context/oeas_etds/article/1265/viewcontent/Muniak_AcomprehensiveEvaluationOfC25_2014_Redacted.pdf

Sea Ice extent is one of the major factors regulating carbon cycling and ecosystem function in the modern Arctic Ocean. It is an essential component of climate models and is crucial for the evaluation of various oceanographic processes that influence a particular region. Yet it is also one of the most difficult attributes of the ocean with respect to our ability for its accurate reconstruction from paleo records. The lack of the detailed records prior to satellite information has encouraged the development of new proxy records for the reconstruction of past sea ice conditions. In recent years, a new monounsaturated sesterterpenoid biomarker for the presence of the Arctic sea ice, termed IP25 (Ice Proxy with 25 carbon atoms), has been proposed based on its observation in environmental records. Relatively few studies have, to date, concentrated on investigating the factors that influence production and fate of IP25, and its universal applicability to the entire Arctic region have never been tested. To investigate the factors influencing IP25 distribution in the environment, its concentrations, along with algal lipid biomarkers (sterols), were examined in a suite of samples, comprising of particulate organic matter from water and ice, and surface sediments from 73 locations in Chukchi and Bering Seas. Also lipid compositions of pelagic and ice-inhabiting plankton communities from two locations were examined after their successful incubation under near in situ conditions, to evaluate possible changes in IP25 abundances in the live cells with the changes in natural community composition. The spatial distribution of the IP25 in the environmental samples displayed variability that could not be explained with any of the environmental factors considered; it was absent in most of the ice, all of the water particle samples and in the cultured cells. Based on these results, IP25 may be useful as a proxy for particular groups of diatoms in polar waters, but cannot be considered a general indicator for the presence of the sea ...