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Woods Hole Oceanographic Institution

Marco Coolen

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Publications
»Bioavailability of soil organic matter and microbial community dynamics upon permafrost thaw
»7000 years of virus-host molecular dynamics in the Black Sea
»Preservation potential of ancient DNA in Pleistocene marine sediments: Implications for paleoenvironmental reconstructions
»Source-specific variability in post-depositional DNA preservation with potential implications for DNA-based paleecological records
»Exploring preserved ancient dinoflagellalte and haptophyte DNA signatures to infer ecological and environmental conditions during sapropel S1 formation in the eastern Mediterranean
»Ancient DNA in lake sediment records
»Vertical distribution of metabolically active eukaryotes in the water column and sediments of the Black Sea
»DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene
»Diversity of Archaea and potential for crenarchaeotal nitrification of group 1.1a in the rivers Rhine and TĂȘt
»Holocene sources of fossil BHPs
»An unusual 17[α],21[β](H)-bacteriohopanetetrol in Holocene sediments from Ace Lake (Antarctica)
»Holocene sources of organic matter in Antarctic fjord
»Variations in spatial and temporal distribution of Archaea in the North Sea
»Archaeal nitrifiers in the Black Sea
»Pleistocene Mediterranean sapropel DNA
»Rapid sulfurisation of highly branched isoprenoid (HBI) alkenes in sulfidic Holocene sediments
»Aerobic and anaerobic methanotrophs in the Black Sea water column
»Fossil DNA in Cretaceous Black Shales: Myth or Reality?
»Sulfur and methane cycling during the Holocene in Ace Lake (Antarctica)
»Ancient algal DNA in the Black Sea
»Archaeal nitrification in the ocean
»Characterization of microbial communities found in the human vagina by analysis of terminal restriction fragment length polymorphisms of 16S rRNA genes
»Biomarker and 16S rDNA evidence for anaerobic oxidation of methane and related carbonate precipitation in deep-sea mud volcanoes of the Sorokin Trough, Black Sea
»Temperature-dependent variation in the distribution of tetraether membrane lipids of marine Crenarchaeota: Implications for TEX86 paleothermometry
»Paleoecology of algae in Ace Lake
»Evolution of the methane cycle in Ace Lake (Antarctica) during the Holocene: Response of methanogens and methanotrophs to environmental change
»Ongoing modification of Mediterranean Pleistocene sapropels mediated by prokaryotes.
»Microbial communities in the chemocline of a hypersaline deep-sea basin (Urania basin, Mediterranean Sea)
»Functional exoenzymes as indicators of metabolically active bacteria in 124,000-year-old sapropel layers of the Eastern Mediterranean Sea
»Specific detection of different phylogenetic groups of chemocline bacteria based on PCR and denaturing gradient gel electrophoresis of 16S rRNA gene fragments
»Analysis of subfossil molecular remains of purple sulfur bacteria in a lake sediment
»Effects of nitrate availability and the presence of Glyceria maxima the composition and activity of the dissimilatory nitrate-reducing bacterial community
»Microbial activities and populations in upper sediment and sapropel layers


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Coolen, M. J. L., J. P. Saenz, L. Giosan, N. Y. Trowbridge, P. Dimitrov, D. Dimitrov and T. I. Eglinton, DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the Holocene, Earth. Planet. Sc. Lett., 284(3-4), 610-621, 2009

Previous studies suggest that the coccolithophorid haptophyte Emiliania huxleyi entered the Black Sea ~ 3400 yrs ago and since then a coccolith ooze defined as Unit I has developed. Unit I sediments contain long-chain alkenones derived from E. huxleyi whereas the alkenone distribution of the deeper coccolith-free sapropel (Unit II) is rather unusual. Alkenone-derived past sea surface temperature (SST) estimates suggest a large difference between Unit II and Unit I, which is likely a result of unusual biological precursors of the alkenones in Unit II. Here, we report a high-resolution stratigraphic analysis of ancient haptophyte DNA to establish the Holocene succession of haptophytes as sources of the alkenones in the Black Sea. Haptophytes related to brackish Isochrysis spp. were the initial sources of alkenones, and appeared immediately after the onset of sapropel deposition (~ 7550 yrs before present [a BP]). As salinity increased, Isochrysis-related haptophytes were slowly replaced by a complex suite of E. huxleyi strains as sources of alkenones. Our paleogenetic data showed that E. huxleyi colonized the Black Sea shortly after the onset of sapropel deposition, ~ 4000 yrs earlier than previously recognized based on their preserved coccoliths. E. huxleyi strains were the most likely source of the previously reported abundant and unusual C36 di-unsaturated “Black Sea alkenone”. Strong haptophyte species and strain-specific effects were observed on the level of unsaturation of alkenones which resulted in spurious alkenone-derived SST estimates before 5250 a BP. In contrast, from ~ 5250 a BP onwards a relatively stable haptophyte assemblage dominated by a different suite of E. huxleyi strains yielded robust alkenone-SST values and indicated a gradual cooling from 19 °C to ~ 15 °C at the top of the record (~ 450 a BP). Full text of article can be found here.

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