Alkenone distribution in Lake Van sediment over the last 270 ka: influence of temperature and haptophyte species composition
MetadataShow full item record
Fossil long-chain alkenones have been used for several decades to reconstruct past ocean surface water temperatures and gained recent interest as a paleotemperature proxy for continental lake settings. However, factors besides temperature can affect alkenone distributions in haptophyte algae, and alkenone compositions can differ between haptophyte species. Alkenone-biosynthesizing haptophyte algae are genetically much more diverse in lakes than in the marine realm, and species-level variations in alkenone compositions could have implications for alkenone paleothermometry. Here, we performed a paired analysis of alkenone distributions and haptophyte species compositions using ancient DNA in up to 270 ka-old sediments of Lake Van in Turkey to reveal a possible species-effect on fossil alkenone distributions and paleotemperature estimates. The same predominant haptophyte in Lake Van today prevailed also since the last ~100 ka. However, a calibration of alkenone paleotemperature especially in the oldest analyzed intervals is complicated due to a more complex haptophyte species composition predominated by a haptophyte (LVHap_6), which is phylogenetically different from sequences recovered from currently existing lakes including Lake Van and from haptophyte species existing in culture. Thepredominance of LVHap_6 coincided with the presence of alkenone MeC38:3 and relatively highMeC37:3/4 (2.4) and MeC38:4/5 ratios (3.0). Uk37 index values in the sediment core over the last 270 ka reflect relative changes in past temperature and are additionally linked to haptophyte species composition. A sustained period of high salinity, as indicated by pore-water salinity measurements, could potentially have triggered the succession of haptophytes as sources of alkenones in Lake Van.
Showing items related by title, author, creator and subject.
DNA and lipid molecular stratigraphic records of haptophyte succession in the Black Sea during the HoloceneCoolen, Marco; Saenz, J.; Giosan, L.; Trowbridge, N.; Dimitrov, P.; Dimitrov, D.; Eglinton, T. (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 ...
Origin and tentative identification of tri to pentaunsaturated ketones in sediments from Lake Fryxell, East AntarcticaJaraula, Caroline; Brassell, S.; Morgan-Kiss, R.; Doran, P.; Kenig, F. (2010)Chromatographic and mass spectrometric analysis of surface sediments from perennially ice-covered Lake Fryxell (McMurdo Dry Valleys, East Antarctica) enabled tentative identification from mass spectral data of previously ...
The distribution pattern of algal flora in saline lakes in Kambalda and Esperance, Western AustraliaHandley, Michelle Anne (2003)The study has attempted to characterise the physicochemical limnology and distribution of algal flora of two salt lake systems in Western Australia, one from the coastal Esperance region and the other from the inland ...