@article{Blum2017, author = {Blum, Rahel}, title = {Eine Schreib{\"u}bung als Einblick in die j{\"u}dische Lebenswelt auf dem Lande}, series = {Genisa-Bl{\"a}tter II}, journal = {Genisa-Bl{\"a}tter II}, editor = {Denz, Rebekka and Rudolf, Gabi}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-104639}, pages = {85 -- 96}, year = {2017}, language = {de} } @article{DenzRudolf2017, author = {Denz, Rebekka and Rudolf, Gabi}, title = {Werkstattbericht: Genisot in Franken}, series = {Genisa-Bl{\"a}tter II}, journal = {Genisa-Bl{\"a}tter II}, editor = {Denz, Rebekka and Rudolf, Gabi}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-104464}, pages = {7 -- 14}, year = {2017}, language = {de} } @article{Weinhold2017, author = {Weinhold, Beate}, title = {‚Ma'oz tsur jeshu'ati'}, series = {Genisa-Bl{\"a}tter II}, journal = {Genisa-Bl{\"a}tter II}, editor = {Denz, Rebekka and Rudolf, Gabi}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-104561}, pages = {45 -- 50}, year = {2017}, language = {de} } @article{Mueller2017, author = {M{\"u}ller, Monika}, title = {Vom Handeln und Schmusen}, series = {Genisa-Bl{\"a}tter II}, journal = {Genisa-Bl{\"a}tter II}, editor = {Denz, Rebekka and Rudolf, Gabi}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-104659}, pages = {111 -- 117}, year = {2017}, language = {de} } @article{ReeseGudmundssonLevermannetal.2017, author = {Reese, Ronja and Gudmundsson, Gudmundur Hilmar and Levermann, Anders and Winkelmann, Ricarda}, title = {The far reach of ice-shelf thinning in Antarctica}, series = {Nature climate change}, volume = {8}, journal = {Nature climate change}, number = {1}, publisher = {Nature Publ. Group}, address = {London}, issn = {1758-678X}, doi = {10.1038/s41558-017-0020-x}, pages = {53 -- 57}, year = {2017}, abstract = {Floating ice shelves, which fringe most of Antarctica's coastline, regulate ice flow into the Southern Ocean1,2,3. Their thinning4,5,6,7 or disintegration8,9 can cause upstream acceleration of grounded ice and raise global sea levels. So far the effect has not been quantified in a comprehensive and spatially explicit manner. Here, using a finite-element model, we diagnose the immediate, continent-wide flux response to different spatial patterns of ice-shelf mass loss. We show that highly localized ice-shelf thinning can reach across the entire shelf and accelerate ice flow in regions far from the initial perturbation. As an example, this 'tele-buttressing' enhances outflow from Bindschadler Ice Stream in response to thinning near Ross Island more than 900 km away. We further find that the integrated flux response across all grounding lines is highly dependent on the location of imposed changes: the strongest response is caused not only near ice streams and ice rises, but also by thinning, for instance, well-within the Filchner-Ronne and Ross Ice Shelves. The most critical regions in all major ice shelves are often located in regions easily accessible to the intrusion of warm ocean waters10,11,12, stressing Antarctica's vulnerability to changes in its surrounding ocean.}, language = {en} } @article{SierLangereisDupontNivetetal.2017, author = {Sier, Mark J. and Langereis, Cor G. and Dupont-Nivet, Guillaume and Feibel, Craig S. and Joordens, Josephine C. A. and van der Lubbe, Jeroen Fiji. and Beck, Catherine C. and Olago, Daniel and Cohen, Andrew}, title = {The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)}, series = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, volume = {42}, journal = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, publisher = {Elsevier}, address = {Oxford}, organization = {WTK Science Team Members}, issn = {1871-1014}, doi = {10.1016/j.quageo.2017.08.004}, pages = {117 -- 129}, year = {2017}, abstract = {One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a \&\#8764;216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the 'Vrica Subchron' previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies.}, language = {en} } @misc{WurzbacherFuchsAttermeyeretal.2017, author = {Wurzbacher, Christian and Fuchs, Andrea and Attermeyer, Katrin and Frindte, Katharina and Grossart, Hans-Peter and Hupfer, Michael and Casper, Peter and Monaghan, Michael T.}, title = {Shifts among Eukaryota, Bacteria, and Archaea define the vertical organization of a lake sediment}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1111}, issn = {1866-8372}, doi = {10.25932/publishup-43196}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-431965}, pages = {18}, year = {2017}, abstract = {Background Lake sediments harbor diverse microbial communities that cycle carbon and nutrients while being constantly colonized and potentially buried by organic matter sinking from the water column. The interaction of activity and burial remained largely unexplored in aquatic sediments. We aimed to relate taxonomic composition to sediment biogeochemical parameters, test whether community turnover with depth resulted from taxonomic replacement or from richness effects, and to provide a basic model for the vertical community structure in sediments. Methods We analyzed four replicate sediment cores taken from 30-m depth in oligo-mesotrophic Lake Stechlin in northern Germany. Each 30-cm core spanned ca. 170 years of sediment accumulation according to 137Cs dating and was sectioned into layers 1-4 cm thick. We examined a full suite of biogeochemical parameters and used DNA metabarcoding to examine community composition of microbial Archaea, Bacteria, and Eukaryota. Results Community β-diversity indicated nearly complete turnover within the uppermost 30 cm. We observed a pronounced shift from Eukaryota- and Bacteria-dominated upper layers (<5 cm) to Bacteria-dominated intermediate layers (5-14 cm) and to deep layers (>14 cm) dominated by enigmatic Archaea that typically occur in deep-sea sediments. Taxonomic replacement was the prevalent mechanism in structuring the community composition and was linked to parameters indicative of microbial activity (e.g., CO2 and CH4 concentration, bacterial protein production). Richness loss played a lesser role but was linked to conservative parameters (e.g., C, N, P) indicative of past conditions. Conclusions By including all three domains, we were able to directly link the exponential decay of eukaryotes with the active sediment microbial community. The dominance of Archaea in deeper layers confirms earlier findings from marine systems and establishes freshwater sediments as a potential low-energy environment, similar to deep sea sediments. We propose a general model of sediment structure and function based on microbial characteristics and burial processes. An upper "replacement horizon" is dominated by rapid taxonomic turnover with depth, high microbial activity, and biotic interactions. A lower "depauperate horizon" is characterized by low taxonomic richness, more stable "low-energy" conditions, and a dominance of enigmatic Archaea.}, language = {en} } @phdthesis{Perillon2017, author = {P{\´e}rillon, C{\´e}cile}, title = {The effect of groundwater on benthic primary producers and their interaction}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-406883}, school = {Universit{\"a}t Potsdam}, pages = {XVII, 180}, year = {2017}, abstract = {In littoral zones of lakes, multiple processes determine lake ecology and water quality. Lacustrine groundwater discharge (LGD), most frequently taking place in littoral zones, can transport or mobilize nutrients from the sediments and thus contribute significantly to lake eutrophication. Furthermore, lake littoral zones are the habitat of benthic primary producers, namely submerged macrophytes and periphyton, which play a key role in lake food webs and influence lake water quality. Groundwater-mediated nutrient-influx can potentially affect the asymmetric competition between submerged macrophytes and periphyton for light and nutrients. While rooted macrophytes have superior access to sediment nutrients, periphyton can negatively affect macrophytes by shading. LGD may thus facilitate periphyton production at the expense of macrophyte production, although studies on this hypothesized effect are missing. The research presented in this thesis is aimed at determining how LGD influences periphyton, macrophytes, and the interactions between these benthic producers. Laboratory experiments were combined with field experiments and measurements in an oligo-mesotrophic hard water lake. In the first study, a general concept was developed based on a literature review of the existing knowledge regarding the potential effects of LGD on nutrients and inorganic and organic carbon loads to lakes, and the effect of these loads on periphyton and macrophytes. The second study includes a field survey and experiment examining the effects of LGD on periphyton in an oligotrophic, stratified hard water lake (Lake Stechlin). This study shows that LGD, by mobilizing phosphorus from the sediments, significantly promotes epiphyton growth, especially at the end of the summer season when epilimnetic phosphorus concentrations are low. The third study focuses on the potential effects of LGD on submerged macrophytes in Lake Stechlin. This study revealed that LGD may have contributed to an observed change in macrophyte community composition and abundance in the shallow littoral areas of the lake. Finally, a laboratory experiment was conducted which mimicked the conditions of a seepage lake. Groundwater circulation was shown to mobilize nutrients from the sediments, which significantly promoted periphyton growth. Macrophyte growth was negatively affected at high periphyton biomasses, confirming the initial hypothesis. More generally, this thesis shows that groundwater flowing into nutrient-limited lakes may import or mobilize nutrients. These nutrients first promote periphyton, and subsequently provoke radical changes in macrophyte populations before finally having a possible influence on the lake's trophic state. Hence, the eutrophying effect of groundwater is delayed and, at moderate nutrient loading rates, partly dampened by benthic primary producers. The present research emphasizes the importance and complexity of littoral processes, and the need to further investigate and monitor the benthic environment. As present and future global changes can significantly affect LGD, the understanding of these complex interactions is required for the sustainable management of lake water quality.}, language = {en} } @misc{HornickBachCrawfurdetal.2017, author = {Hornick, Thomas and Bach, Lennart T. and Crawfurd, Katharine J. and Spilling, Kristian and Achterberg, Eric Pieter and Woodhouse, Jason Nicholas and Schulz, Kai Georg and Brussaard, Corina P. D. and Riebesell, Ulf and Grossart, Hans-Peter}, title = {Ocean acidification impacts bacteria-phytoplankton coupling at low-nutrient conditions}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {667}, issn = {1866-8372}, doi = {10.25932/publishup-41712}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-417126}, pages = {15}, year = {2017}, abstract = {The oceans absorb about a quarter of the annually produced anthropogenic atmospheric carbon dioxide (CO2), resulting in a decrease in surface water pH, a process termed ocean acidification (OA). Surprisingly little is known about how OA affects the physiology of heterotrophic bacteria or the coupling of heterotrophic bacteria to phytoplankton when nutrients are limited. Previous experiments were, for the most part, undertaken during productive phases or following nutrient additions designed to stimulate algal blooms. Therefore, we performed an in situ large-volume mesocosm (similar to 55 m(3)) experiment in the Baltic Sea by simulating different fugacities of CO2 (fCO(2)) extending from present to future conditions. The study was conducted in July-August after the nominal spring bloom, in order to maintain low-nutrient conditions throughout the experiment. This resulted in phytoplankton communities dominated by small-sized functional groups (picophytoplankton). There was no consistent fCO(2)-induced effect on bacterial protein production (BPP), cell-specific BPP (csBPP) or biovolumes (BVs) of either free-living (FL) or particle-associated (PA) heterotrophic bacteria, when considered as individual components (univariate analyses). Permutational Multivariate Analysis of Variance (PERMANOVA) revealed a significant effect of the fCO(2) treatment on entire assemblages of dissolved and particulate nutrients, metabolic parameters and the bacteria-phytoplankton community. However, distance-based linear modelling only identified fCO(2) as a factor explaining the variability observed amongst the microbial community composition, but not for explaining variability within the metabolic parameters. This suggests that fCO(2) impacts on microbial metabolic parameters occurred indirectly through varying physicochemical parameters and microbial species composition. Cluster analyses examining the co-occurrence of different functional groups of bacteria and phytoplankton further revealed a separation of the four fCO(2)-treated mesocosms from both control mesocosms, indicating that complex trophic interactions might be altered in a future acidified ocean. Possible consequences for nutrient cycling and carbon export are still largely unknown, in particular in a nutrient-limited ocean.}, language = {en} } @article{BjornerasWeyhenmeyerEvansetal.2017, author = {Bjorneras, C. and Weyhenmeyer, G. A. and Evans, C. D. and Gessner, M. O. and Grossart, Hans-Peter and Kangur, K. and Kokorite, I. and Kortelainen, P. and Laudon, H. and Lehtoranta, J. and Lottig, N. and Monteith, D. T. and Noges, P. and Noges, T. and Oulehle, F. and Riise, G. and Rusak, J. A. and Raike, A. and Sire, J. and Sterling, S. and Kritzberg, E. S.}, title = {Widespread Increases in Iron Concentration in European and North American Freshwaters}, series = {Global biogeochemical cycles}, volume = {31}, journal = {Global biogeochemical cycles}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0886-6236}, doi = {10.1002/2017GB005749}, pages = {1488 -- 1500}, year = {2017}, abstract = {Recent reports of increasing iron (Fe) concentrations in freshwaters are of concern, given the fundamental role of Fe in biogeochemical processes. Still, little is known about the frequency and geographical distribution of Fe trends or about the underlying drivers. We analyzed temporal trends of Fe concentrations across 340 water bodies distributed over 10 countries in northern Europe and North America in order to gain a clearer understanding of where, to what extent, and why Fe concentrations are on the rise. We found that Fe concentrations have significantly increased in 28\% of sites, and decreased in 4\%, with most positive trends located in northern Europe. Regions with rising Fe concentrations tend to coincide with those with organic carbon (OC) increases. Fe and OC increases may not be directly mechanistically linked, but may nevertheless be responding to common regional-scale drivers such as declining sulfur deposition or hydrological changes. A role of hydrological factors was supported by covarying trends in Fe and dissolved silica, as these elements tend to stem from similar soil depths. A positive relationship between Fe increases and conifer cover suggests that changing land use and expanded forestry could have contributed to enhanced Fe export, although increases were also observed in nonforested areas. We conclude that the phenomenon of increasing Fe concentrations is widespread, especially in northern Europe, with potentially significant implications for wider ecosystem biogeochemistry, and for the current browning of freshwaters.}, language = {en} }