TY  - JOUR
A1  - Rach, Oliver
A1  - Engels, S.
A1  - Kahmen, A.
A1  - Brauer, Achim
A1  - Martin-Puertas, C.
A1  - van Geel, B.
A1  - Sachse, Dirk
T1  - Hydrological and ecological changes in western Europe between 3200 and 2000 years BP derived from lipid biomarker delta D values in lake Meerfelder Maar sediments
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - One of the most significant Late Holocene climate shifts occurred around 2800 years ago, when cooler and wetter climate conditions established in western Europe. This shift coincided with an abrupt change in regional atmospheric circulation between 2760 and 2560 cal years BP, which has been linked to a grand solar minimum with the same duration (the Homeric Minimum). We investigated the temporal sequence of hydroclimatic and vegetation changes across this interval of climatic change (Homeric climate oscillation) by using lipid biomarker stable hydrogen isotope ratios (ED values) and pollen assemblages from the annually-laminated sediment record from lake Meerfelder Maar (Germany). Over the investigated interval (3200-2000 varve years BP), terrestrial lipid biomarker ED showed a gradual trend to more negative values, consistent with the western Europe long-term climate trend of the Late Holocene. At ca. 2640 varve years BP we identified a strong increase in aquatic plants and algal remains, indicating a rapid change in the aquatic ecosystem superimposed on this long-term trend. Interestingly, this aquatic ecosystem change was accompanied by large changes in ED values of aquatic lipid biomarkers, such as nC(21) and nC(23) (by between 22 and 30%(0)). As these variations cannot solely be explained by hydroclimate changes, we suggest that these changes in the Wag value were influenced by changes in n-alkane source organisms. Our results illustrate that if ubiquitous aquatic lipid biomarkers are derived from a limited pool of organisms, changes in lake ecology can be a driving factor for variations on sedimentary lipid MN values, which then could be easily misinterpreted in terms of hydro climatic changes. (C) 2017 Elsevier Ltd. All rights reserved.
KW  - Holocene
KW  - Climate dynamics
KW  - Paleoclimatology
KW  - Western Europe
KW  - Continental biomarkers
KW  - Organic geochemistry
KW  - Stable isotopes
KW  - Vegetation dynamics
Y1  - 2017
U6  - https://doi.org/10.1016/j.quascirev.2017.07.019
SN  - 0277-3791
VL  - 172
SP  - 44
EP  - 54
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Taube, Robert
A1  - Ganzert, Lars
A1  - Grossart, Hans-Peter
A1  - Gleixner, Gerd
A1  - Premke, Katrin
T1  - Organic matter quality structures benthic fatty acid patterns and the abundance of fungi and bacteria in temperate lakes
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - Benthic microbial communities (BMCs) play important roles in the carbon cycle of lakes, and benthic littoral zones in particular have been previously highlighted as biogeochemical hotspots. Dissolved organic matter (DOM) presents the major carbon pool in lakes, and although the effect of DOM composition on the pelagic microbial community composition is widely accepted, little is known about its effect on BMCs, particularly aquatic fungi. Therefore, we investigated the composition of benthic littoral microbial communities in twenty highly diverse lakes in northeast Germany. DOM quality was analyzed via size exclusion chromatography (SEC), fluorescence parallel factor analyses (PRAFACs) and UV-Vis spectroscopy. We determined the BMC composition and biomass using phospholipid-derived fatty acids (PLFA) and extended the interpretation to the analysis of fungi by applying a Bayesian mixed model. We present evidence that the quality of DOM structures the BMCs, which are dominated by heterotrophic bacteria and show low fungal biomass. The fungal biomass increases when the DOM pool is processed by microorganisms of allochthonous origin, whereas the opposite is true for bacteria.
KW  - PLFA
KW  - PARAFAC
KW  - Size exclusion chromatography (SEC)
KW  - Aquatic fungi
KW  - Stable isotopes
KW  - FASTAR
Y1  - 2017
U6  - https://doi.org/10.1016/j.scitotenv.2017.07.256
SN  - 0048-9697
SN  - 1879-1026
VL  - 610
SP  - 469
EP  - 481
PB  - Elsevier
CY  - Amsterdam
ER  -