TY - JOUR A1 - Nwosu, Ebuka Canisius A1 - Roeser, Patricia Angelika A1 - Yang, Sizhong A1 - Pinkerneil, Sylvia A1 - Ganzert, Lars A1 - Dittmann, Elke A1 - Brauer, Achim A1 - Wagner, Dirk A1 - Liebner, Susanne T1 - Species-level spatio-temporal dynamics of cyanobacteria in a hard-water temperate lake in the Southern Baltics JF - Frontiers in microbiology N2 - Cyanobacteria are important primary producers in temperate freshwater ecosystems. However, studies on the seasonal and spatial distribution of cyanobacteria in deep lakes based on high-throughput DNA sequencing are still rare. In this study, we combined monthly water sampling and monitoring in 2019, amplicon sequence variants analysis (ASVs; a proxy for different species) and quantitative PCR targeting overall cyanobacteria abundance to describe the seasonal and spatial dynamics of cyanobacteria in the deep hard-water oligo-mesotrophic Lake Tiefer See, NE Germany. We observed significant seasonal variation in the cyanobacterial community composition (p < 0.05) in the epi- and metalimnion layers, but not in the hypolimnion. In winter-when the water column is mixed-picocyanobacteria (Synechococcus and Cyanobium) were dominant. With the onset of stratification in late spring, we observed potential niche specialization and coexistence among the cyanobacteria taxa driven mainly by light and nutrient dynamics. Specifically, ASVs assigned to picocyanobacteria and the genus Planktothrix were the main contributors to the formation of deep chlorophyll maxima along a light gradient. While Synechococcus and different Cyanobium ASVs were abundant in the epilimnion up to the base of the euphotic zone from spring to fall, Planktothrix mainly occurred in the metalimnetic layer below the euphotic zone where also overall cyanobacteria abundance was highest in summer. Our data revealed two potentially psychrotolerant (cold-adapted) Cyanobium species that appear to cope well under conditions of lower hypolimnetic water temperature and light as well as increasing sediment-released phosphate in the deeper waters in summer. The potential cold-adapted Cyanobium species were also dominant throughout the water column in fall and winter. Furthermore, Snowella and Microcystis-related ASVs were abundant in the water column during the onset of fall turnover. Altogether, these findings suggest previously unascertained and considerable spatiotemporal changes in the community of cyanobacteria on the species level especially within the genus Cyanobium in deep hard-water temperate lakes. KW - Cyanobium KW - picocyanobacteria diversity KW - amplicon sequencing KW - lake monitoring KW - ecological succession KW - lake stratification KW - psychrotolerant Y1 - 2021 U6 - https://doi.org/10.3389/fmicb.2021.761259 SN - 1664-302X VL - 12 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Dräger, Nadine A1 - Plessen, Birgit A1 - Kienel, Ulrike A1 - Siowinski, Michat A1 - Ramisch, Arne A1 - Tjallingii, Rik A1 - Pinkerneil, Sylvia A1 - Brauer, Achim T1 - Hypolimnetic oxygen conditions influence varve preservation and delta C-13 of sediment organic matter in Lake Tiefer See, NE Germany JF - Journal of paleolimnolog N2 - Stable carbon isotopes of sediment organic matter (delta C-13(OM)) are widely applied in paleoenvironmental studies. Interpretations of delta C-13(OM), however, remain challenging and factors that influence delta C-13(OM) may not apply across all lakes. Common explanations for stratigraphic shifts in delta C-13(OM) include changes in lake productivity or changes in inputs of allochthonous OM. We investigated the influence of different oxygen conditions (oxic versus anoxic) on the delta C-13(OM) values in the sediments of Lake Tiefer See. We analysed (1) a long sediment core from the deepest part of the lake, (2) two short, sediment-water interface cores from shallower water depths, and (3) OM in the water column, i.e. from sediment traps. Fresh OM throughout the entire water column showed a relatively constant delta C-13(OM) value of approximately -30.5 parts per thousand. Similar values, about -31 parts per thousand, were obtained for well-varved sediments in both the long and short, sediment-water interface cores. In contrast, delta C-13(OM) values from non-varved sediments in all cores were significantly less negative (-29 parts per thousand). The delta C-13(OM) values in the sediment-water interface cores from different water depths differ for sediments of the same age, if oxygen conditions at the time of deposition were different at these sites, as suggested by the state of varve preservation. Sediments deposited from AD 1924 to 1980 at 62m water depth are varved and exhibit delta C-13(OM) values around -31 parts per thousand, whereas sediments of the same age in the core from 35m water depth are not varved and show less negative delta C-13(OM) values of about -29 parts per thousand. The relation between varve occurrence and delta C-13(OM) values suggests that delta C-13(OM) is associated with oxygen conditions because varve preservation depends on hypolimnetic anoxia. A mechanism that likely influences delta C-13(OM) is selective degradation of OM under oxic conditions, such that organic components with more negative delta C-13(OM) are preferably decomposed, leading to less negative delta C-13(OM) values in the remaining, undegraded OM pool. Greater decomposition of OM in non-varved sediments is supported by lower TOC concentrations in these deposits (similar to 5%) compared to well-varved sediments (similar to 15%). Even in lakes that display small variations in productivity and terrestrial OM input through time, large spatial and temporal differences in hypolimnetic oxygen concentrations may be an important factor controlling sediment delta C-13(OM). KW - Carbon stable isotopes KW - Hypolimnetic oxygen KW - Organic matter degradation KW - Varves Y1 - 2019 U6 - https://doi.org/10.1007/s10933-019-00084-2 SN - 0921-2728 SN - 1573-0417 VL - 62 IS - 2 SP - 181 EP - 194 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Heinrich, Ingo A1 - Balanzategui, Daniel A1 - Bens, Oliver A1 - Blasch, Gerald A1 - Blume, Theresa A1 - Boettcher, Falk A1 - Borg, Erik A1 - Brademann, Brian A1 - Brauer, Achim A1 - Conrad, Christopher A1 - Dietze, Elisabeth A1 - Dräger, Nadine A1 - Fiener, Peter A1 - Gerke, Horst H. A1 - Güntner, Andreas A1 - Heine, Iris A1 - Helle, Gerhard A1 - Herbrich, Marcus A1 - Harfenmeister, Katharina A1 - Heussner, Karl-Uwe A1 - Hohmann, Christian A1 - Itzerott, Sibylle A1 - Jurasinski, Gerald A1 - Kaiser, Knut A1 - Kappler, Christoph A1 - Koebsch, Franziska A1 - Liebner, Susanne A1 - Lischeid, Gunnar A1 - Merz, Bruno A1 - Missling, Klaus Dieter A1 - Morgner, Markus A1 - Pinkerneil, Sylvia A1 - Plessen, Birgit A1 - Raab, Thomas A1 - Ruhtz, Thomas A1 - Sachs, Torsten A1 - Sommer, Michael A1 - Spengler, Daniel A1 - Stender, Vivien A1 - Stüve, Peter A1 - Wilken, Florian T1 - Interdisciplinary Geo-ecological Research across Time Scales in the Northeast German Lowland Observatory (TERENO-NE) JF - Vadose zone journal N2 - The Northeast German Lowland Observatory (TERENO-NE) was established to investigate the regional impact of climate and land use change. TERENO-NE focuses on the Northeast German lowlands, for which a high vulnerability has been determined due to increasing temperatures and decreasing amounts of precipitation projected for the coming decades. To facilitate in-depth evaluations of the effects of climate and land use changes and to separate the effects of natural and anthropogenic drivers in the region, six sites were chosen for comprehensive monitoring. In addition, at selected sites, geoarchives were used to substantially extend the instrumental records back in time. It is this combination of diverse disciplines working across different time scales that makes the observatory TERENO-NE a unique observation platform. We provide information about the general characteristics of the observatory and its six monitoring sites and present examples of interdisciplinary research activities at some of these sites. We also illustrate how monitoring improves process understanding, how remote sensing techniques are fine-tuned by the most comprehensive ground-truthing site DEMMIN, how soil erosion dynamics have evolved, how greenhouse gas monitoring of rewetted peatlands can reveal unexpected mechanisms, and how proxy data provides a long-term perspective of current ongoing changes. Y1 - 2018 U6 - https://doi.org/10.2136/vzj2018.06.0116 SN - 1539-1663 VL - 17 IS - 1 PB - Soil Science Society of America CY - Madison ER - TY - JOUR A1 - Kienel, Ulrike A1 - Plessen, Birgit A1 - Schettler, Georg A1 - Weise, Stephan A1 - Pinkerneil, Sylvia A1 - Boehnel, Harald A1 - Englebrecht, Amy C. A1 - Haug, Gerald H. T1 - Sensitivity of a hypersaline crater lake to the seasonality of rainfall, evaporation, and guano supply JF - Fundamental and applied limnology : official journal of the International Association of Theoretical and Applied Limnology N2 - The hypersaline crater lake and its catchment on seabird island Isabel (Pacific, off Mexico) was studied to explore the influence of strong seasonal variations in rainfall/evaporation and guano contribution on its limnology. The hypersaline lake water (HSW, 78 %) is up to 2.2-times enriched in inert ions relative to mean seawater. Rainfall during summer dilutes the HSW to form a less saline rainwater body (RWB) above a chemolimnion between 2 and 4 m water depth. The RWB is inhabited first by diatoms and ostracods followed later on by cyanobacteria and ciliates. Evaporation of > 1.5 m depth of lake water over the dry season increases the salinity of the RWB until the water column becomes isohaline at HSW concentrations in the late dry season. Differences in the stable isotope composition of water and primary producers in RWB and HSW reflect this development. Introduction of seabird guano and the decrease of salinity fuel a high primary production in the RWB with higher delta(CDIC)-C-13 and delta(13)Corg of particulate organic matter than in the HSW. The high N supply leads to high delta N-15 NH4 values (+ 39 % in the HSW) as the consequence of ammonia volatilization that is strongest during guano maturation and with evaporative salinity increase from the HSW. Precipitation of carbonate (calcite and aragonite) from the RWB and the HSW is hindered by the high concentration of guano-derived P. This inhibition may be overcome with evaporative supersaturation during particularly dry conditions. Carbonate may also precipitate during particularly wet conditions from the dilute RWB, where the P-concentration is reduced during an active phytoplankton production that raises the pH. Differences in the stable isotope signatures of carbon and oxygen in HSW and RWB (+ 5 % delta(CDIC)-C-13 and -3 % d18OH2O) suggest the processes of carbonate precipitation can be distinguished based on the isotope signature of the carbonates deposited. Changes in the lake system are indicated when lower temperatures and higher rainfall in the 2006 wet season introduced more and less mature guano to the lake. The lower pH was accompanied by lower ammonia volatilization and carbonate precipitation as indicated by an increased concentration of NH4, Ca, Sr and DIC, while delta H-2, delta(NNH4)-N-15, and salinity were lower. According to our results, the observed sediment laminations should reflect the introduction of catchment material (including guano) with runoff, the RWB plankton production, and the carbonate precipitation in relation to its origin and seasonality. KW - ammonia volatilization KW - carbonate precipitation KW - chemocline KW - guano KW - hypersaline lake KW - stable isotopes Y1 - 2013 U6 - https://doi.org/10.1127/1863-9135/2013/0405 SN - 1863-9135 VL - 183 IS - 2 SP - 135 EP - 152 PB - Schweizerbart CY - Stuttgart ER -