Identification of organic matter sources in sulfidic late Holocene Antarctic fjord sediments from fossil rDNA sequence analysis
Coolen, Marco J. L.
Volkman, John K.
Sinninghe Damste, Jaap S.
MetadataShow full item record
The 18S ribosomal DNA (rDNA) isolated from sulfidic Holocene sediments and particulate organic matter in the water column of the stratified Small Meromictic Basin (SMB) in Ellis Fjord (eastern Antarctica) was analyzed to identify possible biological sources of organic matter. Previous work had shown that the sediments contained numerous diatom frustules and high contents of a highly branched isoprenoid (HBI) C25:2 alkene (which is a specific biomarker of certain species of the diatom genera Navicula, Haslea, Pleurosigma, or Rhizosolenia), so we focused our search on preserved fossil 18S rDNA of diatoms using sensitive polymerase chain reaction (PCR) approaches. We did not find diatom-derived fossil 18S rDNA using general eukaryotic primers, and even when we used primers selective for diatom 18S rDNA, we only identified a Chaetoceros phylotype, which is known to form cysts in the SMB but is not a likely source of the C25:2 HBI. When we used PCR/denaturing gradient gel electrophoresis methods specific to phylotypes within the HBI-biosynthesizing genera, we were able to identify three phylotypes in the sediments related to HBI-producing strains of the genera Haslea and Navicula. The ancient DNA data thus provided a limited, but valuable, view of the diversity of late Holocene primary producers with a particular bias to specific components of the biota that were better preserved such as the Chaetoceros cysts. This use of paleogenetics also revealed unexpected possible sources of organic matter such as novel stramenopiles for which no specific lipid biomarkers are known and thus would not have been identified based on traditional lipid stratigraphy alone.
Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 22 (2007): PA2211, doi:10.1029/2006PA001309.
Showing items related by title, author, creator and subject.
Geochemistry of surface sediments from the fjords of Northern Chilean Patagonia (44–47°S) : spatial variability and implications for paleoclimate reconstructions Bertrand, Sebastien; Hughen, Konrad A.; Sepulveda, Julio; Pantoja, Silvio (2011-09-22)The Patagonian fjords have a clear potential to provide high-resolution sedimentary and geochemical records of past climate and environmental change in the Southern Andes. To improve our ability to interpret these proxy ...
Straneo, Fiamma; Hamilton, Gordon S.; Sutherland, David A.; Stearns, Leigh A.; Davidson, Fraser J. M.; Hammill, Mike O.; Stenson, Garry B.; Rosing-Asvid, Aqqalu (2009-12-17)The recent rapid increase in mass loss from the Greenland Ice Sheet is primarily attributed to an acceleration of outlet glaciers. One possible cause is increased melting at the ice/ocean interface driven by the synchronous ...
Estimating ocean heat transports and submarine melt rates in Sermilik Fjord, Greenland, using lowered acoustic Doppler current profiler (LADCP) velocity profiles Sutherland, David A.; Straneo, Fiamma (International Glaciological Society, 2012-11-01)Submarine melting at the ice-ocean interface is a significant term in the mass balance of marine-terminating outlet glaciers. However, obtaining direct measurements of the submarine melt rate, or the ocean heat transport ...