Title | Group 2i Isochrysidales produce characteristic alkenones reflecting sea ice distribution |
Publication Type | Journal Article |
Year of Publication | 2021 |
Authors | Wang KJiaxi, Huang Y, Majaneva M, Belt ST, Liao S, Novak J, Kartzinel TR, Herbert TD, Richter N, Cabedo-Sanz P |
Journal | Nature Communications |
Volume | 12 |
Pagination | 15 |
Date Published | dec |
ISSN | 2041-1723 |
Keywords | RCC107, RCC1195, RCC1334, RCC5486 |
Abstract | Alkenones are biomarkers produced solely by algae in the order Isochrysidales that have been used to reconstruct sea surface temperature (SST) since the 1980s. However, alkenone-based SST reconstructions in the northern high latitude oceans show significant bias towards warmer temperatures in core-tops, diverge from other SST proxies in down core records, and are often accompanied by anomalously high relative abundance of the C 37 tetra-unsaturated methyl alkenone (%C 37:4 ). Elevated %C 37:4 is widely interpreted as an indicator of low sea surface salinity from polar water masses, but its biological source has thus far remained elusive. Here we identify a lineage of Isochrysidales that is responsible for elevated C 37:4 methyl alkenone in the northern high latitude oceans through next-generation sequencing and lab-culture experiments. This Isochrysidales lineage co-occurs widely with sea ice in marine environments and is distinct from other known marine alkenone-producers, namely Emiliania huxleyi and Gephyrocapsa oceanica . More importantly, the %C 37:4 in seawater filtered particulate organic matter and surface sediments is significantly correlated with annual mean sea ice concentrations. In sediment cores from the Svalbard region, the %C 37:4 concentration aligns with the Greenland temperature record and other qualitative regional sea ice records spanning the past 14 kyrs, reflecting sea ice concentrations quantitatively. Our findings imply that %C 37:4 is a powerful proxy for reconstructing sea ice conditions in the high latitude oceans on thousand- and, potentially, on million-year timescales. |
URL | http://dx.doi.org/10.1038/s41467-020-20187-z http://www.nature.com/articles/s41467-020-20187-z |
DOI | 10.1038/s41467-020-20187-z |