caa a22 4500 606149279 CHVBK 20210128100533.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00531-015-1219-6 doi (NATIONALLICENCE)springer-10.1007/s00531-015-1219-6 Microbial abundance in lacustrine sediments: a case study from Lake Van, Turkey [Elektronische Daten] [Jens Kallmeyer, Sina Grewe, Clemens Glombitza, J. Kitte] The ICDP "PaleoVan” drilling campaign at Lake Van, Turkey, provided a long (>100m) record of lacustrine subsurface sedimentary microbial cell abundance. After the ICDP campaign at Potrok Aike, Argentina, this is only the second time deep lacustrine cell counts have been documented. Two sites were cored and revealed a strikingly similar cell distribution despite differences in organic matter content and microbial activity. Although shifted towards higher values, cell counts from Lake Potrok Aike, Argentina, reveal very similar distribution patterns with depth. The lacustrine cell count data are significantly different from published marine records; the most probable cause is differences in sedimentary organic matter composition with marine sediments containing a higher fraction of labile organic matter. Previous studies showed that microbial activity and abundance increase centimetres to metres around geologic interfaces. The finely laminated Lake Van sediment allowed studying this phenomenon on the microscale. We sampled at the scale of individual laminae, and in some depth intervals, we found large differences in microbial abundance between the different laminae. This small-scale heterogeneity is normally overlooked due to much larger sampling intervals that integrate over several centimetres. However, not all laminated intervals exhibit such large differences in microbial abundance, and some non-laminated horizons show large variability on the millimetre scale as well. The reasons for such contrasting observations remain elusive, but indicate that heterogeneity of microbial abundance in subsurface sediments has not been taken into account sufficiently. These findings have implications not just for microbiological studies but for geochemistry as well, as the large differences in microbial abundance clearly show that there are distinct microhabitats that deviate considerably from the surrounding layers. The Author(s), 2015 Subsurface biosphere nationallicence Deep biosphere nationallicence Lake Van nationallicence Cell counts nationallicence Lacustrine sediment nationallicence Kallmeyer Jens GFZ German Research Centre for Geosciences, Telegrafenberg, 14473, Potsdam, Germany aut Grewe Sina Earth and Environmental Sciences, University of Potsdam, Karl-Liebknecht Straße, 14476, Potsdam, Germany aut Glombitza Clemens Center for Geomicrobiology, Aarhus University, Ny Munkegade 114, 8000, Århus C, Denmark aut Kitte J. GFZ German Research Centre for Geosciences, Telegrafenberg, 14473, Potsdam, Germany aut International Journal of Earth Sciences Springer Berlin Heidelberg 104/6(2015-09-01), 1667-1677 1437-3254 104:6<1667 2015 104 531 https://doi.org/10.1007/s00531-015-1219-6 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00531-015-1219-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kallmeyer Jens GFZ German Research Centre for Geosciences, Telegrafenberg, 14473, Potsdam, Germany aut NATIONALLICENCE 700 1- Grewe Sina Earth and Environmental Sciences, University of Potsdam, Karl-Liebknecht Straße, 14476, Potsdam, Germany aut NATIONALLICENCE 700 1- Glombitza Clemens Center for Geomicrobiology, Aarhus University, Ny Munkegade 114, 8000, Århus C, Denmark aut NATIONALLICENCE 700 1- Kitte J. GFZ German Research Centre for Geosciences, Telegrafenberg, 14473, Potsdam, Germany aut NATIONALLICENCE 773 0- International Journal of Earth Sciences Springer Berlin Heidelberg 104/6(2015-09-01), 1667-1677 1437-3254 104:6<1667 2015 104 531