TY - JOUR A1 - Mehner, T. A1 - Attermeyer, Katrin A1 - Brauns, Mario A1 - Brothers, Soren M. A1 - Diekmann, J. A1 - Gaedke, Ursula A1 - Grossart, Hans-Peter A1 - Koehler, J. A1 - Lischke, Betty A1 - Meyer, N. A1 - Scharnweber, Inga Kristin A1 - Syvaranta, J. A1 - Vanni, M. J. A1 - Hilt, S. T1 - Weak Response of Animal Allochthony and Production to Enhanced Supply of Terrestrial Leaf Litter in Nutrient-Rich Lakes JF - Ecosystems N2 - Ecosystems are generally linked via fluxes of nutrients and energy across their boundaries. For example, freshwater ecosystems in temperate regions may receive significant inputs of terrestrially derived carbon via autumnal leaf litter. This terrestrial particulate organic carbon (POC) is hypothesized to subsidize animal production in lakes, but direct evidence is still lacking. We divided two small eutrophic lakes each into two sections and added isotopically distinct maize litter to the treatment sections to simulate increased terrestrial POC inputs via leaf litter in autumn. We quantified the reliance of aquatic consumers on terrestrial resources (allochthony) in the year subsequent to POC additions by applying mixing models of stable isotopes. We also estimated lake-wide carbon (C) balances to calculate the C flow to the production of the major aquatic consumer groups: benthic macroinvertebrates, crustacean zooplankton, and fish. The sum of secondary production of crustaceans and benthic macroinvertebrates supported by terrestrial POC was higher in the treatment sections of both lakes. In contrast, total secondary and tertiary production (supported by both autochthonous and allochthonous C) was higher in the reference than in the treatment sections of both lakes. Average aquatic consumer allochthony per lake section was 27-40%, although terrestrial POC contributed less than about 10% to total organic C supply to the lakes. The production of aquatic consumers incorporated less than 5% of the total organic C supply in both lakes, indicating a low ecological efficiency. We suggest that the consumption of terrestrial POC by aquatic consumers facilitates a strong coupling with the terrestrial environment. However, the high autochthonous production and the large pool of autochthonous detritus in these nutrient-rich lakes make terrestrial POC quantitatively unimportant for the C flows within food webs. KW - stable isotopes KW - terrestrial subsidy KW - carbon budget KW - ecological efficiency KW - benthic food web KW - pelagic food web Y1 - 2016 U6 - https://doi.org/10.1007/s10021-015-9933-2 SN - 1432-9840 SN - 1435-0629 VL - 19 SP - 311 EP - 325 PB - Springer CY - New York ER - TY - JOUR A1 - Premke, Katrin A1 - Attermeyer, Katrin A1 - Augustin, Jürgen A1 - Cabezas, Alvaro A1 - Casper, Peter A1 - Deumlich, Detlef A1 - Gelbrecht, Jörg A1 - Gerke, Horst H. A1 - Gessler, Arthur A1 - Großart, Hans-Peter A1 - Hilt, Sabine A1 - Hupfer, Michael A1 - Kalettka, Thomas A1 - Kayler, Zachary A1 - Lischeid, Gunnar A1 - Sommer, Michael A1 - Zak, Dominik T1 - The importance of landscape diversity for carbon fluxes at the landscape level: small-scale heterogeneity matters JF - Wiley Interdisciplinary Reviews : Water N2 - Landscapes can be viewed as spatially heterogeneous areas encompassing terrestrial and aquatic domains. To date, most landscape carbon (C) fluxes have been estimated by accounting for terrestrial ecosystems, while aquatic ecosystems have been largely neglected. However, a robust assessment of C fluxes on the landscape scale requires the estimation of fluxes within and between both landscape components. Here, we compiled data from the literature on C fluxes across the air–water interface from various landscape components. We simulated C emissions and uptake for five different scenarios which represent a gradient of increasing spatial heterogeneity within a temperate young moraine landscape: (I) a homogeneous landscape with only cropland and large lakes; (II) separation of the terrestrial domain into cropland and forest; (III) further separation into cropland, forest, and grassland; (IV) additional division of the aquatic area into large lakes and peatlands; and (V) further separation of the aquatic area into large lakes, peatlands, running waters, and small water bodies These simulations suggest that C fluxes at the landscape scale might depend on spatial heterogeneity and landscape diversity, among other factors. When we consider spatial heterogeneity and diversity alone, small inland waters appear to play a pivotal and previously underestimated role in landscape greenhouse gas emissions that may be regarded as C hot spots. Approaches focusing on the landscape scale will also enable improved projections of ecosystems’ responses to perturbations, e.g., due to global change and anthropogenic activities, and evaluations of the specific role individual landscape components play in regional C fluxes. WIREs Water 2016, 3:601–617. doi: 10.1002/wat2.1147 Y1 - 2016 U6 - https://doi.org/10.1002/wat2.1147 SN - 2049-1948 SN - 2049-1948 VL - 3 SP - 601 EP - 617 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Wurzbacher, Christian A1 - Fuchs, Andrea A1 - Attermeyer, Katrin A1 - Frindte, Katharina A1 - Grossart, Hans-Peter A1 - Hupfer, Michael A1 - Casper, Peter A1 - Monaghan, Michael T. T1 - Shifts among Eukaryota, Bacteria, and Archaea define the vertical organization of a lake sediment JF - Microbiome N2 - 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 Cs-137 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 beta-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. KW - Archaea KW - Eukaryota KW - Bacteria KW - Community KW - Freshwater KW - Lake KW - DNA metabarcoding KW - Beta-diversity KW - Sediment KW - Turnover Y1 - 2017 U6 - https://doi.org/10.1186/s40168-017-0255-9 SN - 2049-2618 VL - 5 PB - BioMed Central CY - London ER - TY - GEN A1 - Wurzbacher, Christian A1 - Fuchs, Andrea A1 - Attermeyer, Katrin A1 - Frindte, Katharina A1 - Grossart, Hans-Peter A1 - Hupfer, Michael A1 - Casper, Peter A1 - Monaghan, Michael T. T1 - Shifts among Eukaryota, Bacteria, and Archaea define the vertical organization of a lake sediment T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1111 KW - Archaea KW - Eukaryota KW - Bacteria KW - community KW - freshwater KW - lake KW - DNA metabarcoding KW - beta-diversity KW - sediment KW - turnover Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-431965 SN - 1866-8372 IS - 1111 ER - TY - JOUR A1 - Lischke, Betty A1 - Weithoff, Guntram A1 - Wickham, Stephen A. A1 - Attermeyer, Katrin A1 - Großart, Hans-Peter A1 - Scharnweber, Inga Kristin A1 - Hilt, Sabine A1 - Gaedke, Ursula T1 - Large biomass of small feeders: ciliates may dominate herbivory in eutrophic lakes JF - Journal of plankton research N2 - The importance of ciliates as herbivores and in biogeochemical cycles is increasingly recognized. An opportunity to observe the potential consequences of zooplankton dominated by ciliates arose when winter fish kills resulted in strong suppression of crustaceans by young planktivorous fish in two shallow lakes. On an annual average, ciliates made up 38-76% of the total zooplankton biomass in both lakes during two subsequent years. Consequently, ciliate biomass and their estimated grazing potential were extremely high compared with other lakes of various trophic states and depths. Grazing estimates based on abundance and size suggest that ciliates should have cleared the water column of small (<5 mu m) and intermediate (5-50 mu m) sized phytoplankton more than once a day. Especially, small feeders within the ciliates were important, likely exerting a strong top-down control on small phytoplankton. Particle-attached bacteria were presumably strongly suppressed by intermediate-sized ciliate feeders. In contrast to other lakes, large phytoplankton was proportionately very abundant. The phytoplankton community had a high evenness, which may be attributed to the feeding by numerous fast growing and selective ciliate species. Our study highlights ciliates as an important trophic link and adds to the growing awareness of the role of winter processes for plankton dynamics. KW - phytoplankton KW - crustaceans KW - rotifers KW - filtration rate KW - winter fish kill Y1 - 2016 U6 - https://doi.org/10.1093/plankt/fbv102 SN - 0142-7873 SN - 1464-3774 VL - 38 SP - 2 EP - 15 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Frindte, Katharina A1 - Eckert, Werner A1 - Attermeyer, Katrin A1 - Grossart, Hans-Peter T1 - Internal wave-induced redox shifts affect biogeochemistry and microbial activity in sediments - a simulation experiment JF - Biogeochemistry N2 - Internal waves (seiches) are well-studied physical processes in stratified lakes, but their effects on sediment porewater chemistry and microbiology are still largely unexplored. Due to pycnocline oscillations, sediments are exposed to recurrent changes between epilimnetic and hypolimnetic water. This results in strong differences of environmental conditions, which should be reflected in the responses of redox-sensitive biogeochemical processes at both, the sediment-water interface and deeper sediment layers. We tested in a series of mesocosm experiments the influence of seiche-induced redox changes on porewater chemistry and bacterial activity in the sediments under well controlled conditions. Thereby, we excluded effects of changes in current and temperature regimes. For a period of 10 days, intact sediment cores from oligotrophic Lake Stechlin were incubated under constant (either oxic or anoxic) or alternating redox conditions. Solute concentrations were measured as porewater profiles in the sediment, while microbial activity was determined in the upper 0.5 cm of sediment. Oxic and alternating redox conditions resulted in similar ammonium, phosphate, and methane porewater concentrations, while concentrations of each analyte were considerably higher in anoxic cores. Microbial activity was clearly lower in the anoxic cores than in the oxic and the alternating cores. In conclusion, cores with intermittent anoxic phases of up to 24 hours do not differ in biogeochemistry and microbial activities from static oxic sediments. However, due to various physical processes seiches cause oxygen to penetrate deeper into sediment layers, which affects sediment redox gradients and increase microbial activity in seiche-influenced sediments. KW - Internal waves KW - Sediment KW - Sediment-water interface KW - Core incubation experiments KW - Porewater profiles KW - Redox conditions KW - Microbial activities Y1 - 2013 U6 - https://doi.org/10.1007/s10533-012-9769-1 SN - 0168-2563 VL - 113 IS - 1-3 SP - 423 EP - 434 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Wurzbacher, Christian A1 - Warthmann, Norman A1 - Bourne, Elizabeth Charlotte A1 - Attermeyer, Katrin A1 - Allgaier, Martin A1 - Powell, Jeff R. A1 - Detering, Harald A1 - Mbedi, Susan A1 - Großart, Hans-Peter A1 - Monaghan, Michael T. T1 - High habitat-specificity in fungal communities in oligo-mesotrophic, temperate Lake Stechlin (North-East Germany) JF - MycoKeys N2 - Freshwater fungi are a poorly studied ecological group that includes a high taxonomic diversity. Most studies on aquatic fungal diversity have focused on single habitats, thus the linkage between habitat heterogeneity and fungal diversity remains largely unexplored. We took 216 samples from 54 locations representing eight different habitats in the meso-oligotrophic, temperate Lake Stechlin in North-East Germany. These included the pelagic and littoral water column, sediments, and biotic substrates. We performed high throughput sequencing using the Roche 454 platform, employing a universal eukaryotic marker region within the large ribosomal subunit (LSU) to compare fungal diversity, community structure, and species turnover among habitats. Our analysis recovered 1027 fungal OTUs (97% sequence similarity). Richness estimates were highest in the sediment, biofilms, and benthic samples (189-231 OTUs), intermediate in water samples (42-85 OTUs), and lowest in plankton samples (8 OTUs). NMDS grouped the eight studied habitats into six clusters, indicating that community composition was strongly influenced by turnover among habitats. Fungal communities exhibited changes at the phylum and order levels along three different substrate categories from littoral to pelagic habitats. The large majority of OTUs (> 75%) could not be classified below the order level due to the lack of aquatic fungal entries in public sequence databases. Our study provides a first estimate of lake-wide fungal diversity and highlights the important contribution of habitat heterogeneity to overall diversity and community composition. Habitat diversity should be considered in any sampling strategy aiming to assess the fungal diversity of a water body. KW - Freshwater fungi KW - aquatic fungi KW - metabarcoding KW - LSU KW - GMYC KW - habitat specificity KW - Chytridiomycota KW - Cryptomycota KW - Rozellomycota KW - community ecology KW - lake ecosystem KW - biofilm KW - sediment KW - plankton KW - water sample KW - benthos KW - reed KW - fungal diversity Y1 - 2016 U6 - https://doi.org/10.3897/mycokeys.16.9646 SN - 1314-4057 SN - 1314-4049 VL - 41 SP - 17 EP - 44 PB - Pensoft Publ. CY - Sofia ER - TY - JOUR A1 - Attermeyer, Katrin A1 - Hornick, T. A1 - Kayler, Z. E. A1 - Bahr, A. A1 - Zwirnmann, E. A1 - Grossart, Hans-Peter A1 - Premke, K. T1 - Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition JF - Biogeosciences N2 - Dissolved organic carbon (DOC) concentrations - mainly of terrestrial origin - are increasing worldwide in inland waters. Heterotrophic bacteria are the main consumers of DOC and thus determine DOC temporal dynamics and availability for higher trophic levels. Our aim was to study bacterial carbon (C) turnover with respect to DOC quantity and chemical quality using both allochthonous and autochthonous DOC sources. We incubated a natural bacterial community with allochthonous C (C-13-labeled beech leachate) and increased concentrations and pulses (intermittent occurrence of organic matter input) of autochthonous C (phytoplankton lysate). We then determined bacterial C consumption, activities, and community composition together with the C flow through bacteria using stable C isotopes. The chemical analysis of single sources revealed differences in aromaticity and low-and high-molecular-weight substance fractions (LMWS and HMWS, respectively) between allochthonous and autochthonous C sources. Both DOC sources (allochthonous and autochthonous DOC) were metabolized at a high bacterial growth efficiency (BGE) around 50%. In treatments with mixed sources, rising concentrations of added autochthonous DOC resulted in a further, significant increase in bacterial DOC consumption of up to 68% when nutrients were not limiting. This rise was accompanied by a decrease in the humic substance (HS) fraction and an increase in bacterial biomass. Changes in DOC concentration and consumption in mixed treatments did not affect bacterial community composition (BCC), but BCC differed in single vs. mixed incubations. Our study highlights that DOC quantity affects bacterial C consumption but not BCC in nutrient-rich aquatic systems. BCC shifted when a mixture of allochthonous and autochthonous C was provided simultaneously to the bacterial community. Our results indicate that chemical quality rather than source of DOC per se (allochthonous vs. autochthonous) determines bacterial DOC turnover. Y1 - 2014 U6 - https://doi.org/10.5194/bg-11-1479-2014 SN - 1726-4170 SN - 1726-4189 VL - 11 IS - 6 SP - 1479 EP - 1489 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Mehner, Thomas A1 - Lischke, Betty A1 - Scharnweber, Inga Kristin A1 - Attermeyer, Katrin A1 - Brothers, Soren A1 - Gaedke, Ursula A1 - Hilt, Sabine A1 - Brucet, Sandra T1 - Empirical correspondence between trophic transfer efficiency in freshwater food webs and the slope of their size spectra JF - Ecology : a publication of the Ecological Society of America N2 - The density of organisms declines with size, because larger organisms need more energy than smaller ones and energetic losses occur when larger organisms feed on smaller ones. A potential expression of density-size distributions are Normalized Biomass Size Spectra (NBSS), which plot the logarithm of biomass independent of taxonomy within bins of logarithmic organismal size, divided by the bin width. Theoretically, the NBSS slope of multi-trophic communities is exactly - 1.0 if the trophic transfer efficiency (TTE, ratio of production rates between adjacent trophic levels) is 10% and the predator-prey mass ratio (PPMR) is fixed at 10(4). Here we provide evidence from four multi-trophic lake food webs that empirically estimated TTEs correspond to empirically estimated slopes of the respective community NBSS. Each of the NBSS considered pelagic and benthic organisms spanning size ranges from bacteria to fish, all sampled over three seasons in 1 yr. The four NBSS slopes were significantly steeper than -1.0 (range -1.14 to -1.19, with 95% CIs excluding -1). The corresponding average TTEs were substantially lower than 10% in each of the four food webs (range 1.0% to 3.6%, mean 1.85%). The overall slope merging all biomass-size data pairs from the four systems (-1.17) was almost identical to the slope predicted from the arithmetic mean TTE of the four food webs (-1.18) assuming a constant PPMR of 10(4). Accordingly, our empirical data confirm the theoretically predicted quantitative relationship between TTE and the slope of the biomass-size distribution. Furthermore, we show that benthic and pelagic organisms can be merged into a community NBSS, but future studies have yet to explore potential differences in habitat-specific TTEs and PPMRs. We suggest that community NBSS may provide valuable information on the structure of food webs and their energetic pathways, and can result in improved accuracy of TTE-estimates. KW - energetic equivalence rule KW - metabolic theory of ecology KW - multi-trophic communities KW - normalized biomass size spectra KW - pelagic and benthic lake habitats KW - size of organisms Y1 - 2018 U6 - https://doi.org/10.1002/ecy.2347 SN - 0012-9658 SN - 1939-9170 VL - 99 IS - 6 SP - 1463 EP - 1472 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Attermeyer, Katrin A1 - Tittel, Joerg A1 - Allgaier, Martin A1 - Frindte, Katharina A1 - Wurzbacher, Christian A1 - Hilt, Sabine A1 - Kamjunke, Norbert A1 - Grossart, Hans-Peter T1 - Effects of Light and Autochthonous Carbon Additions on Microbial Turnover of Allochthonous Organic Carbon and Community Composition JF - Microbial ecology N2 - The fate of allochthonous dissolved organic carbon (DOC) in aquatic systems is primarily controlled by the turnover of heterotrophic bacteria. However, the roles that abiotic and biotic factors such as light and DOC release by aquatic primary producers play in the microbial decomposition of allochthonous DOC is not well understood. We therefore tested if light and autochthonous DOC additions would increase allochthonous DOC decomposition rates and change bacterial growth efficiencies and community composition (BCC). We established continuous growth cultures with different inocula of natural bacterial communities and alder leaf leachates (DOCleaf) with and without light exposure before amendment. Furthermore, we incubated DOCleaf together with autochthonous DOC from lysed phytoplankton cultures (DOCphyto). Our results revealed that pretreatments of DOCleaf with light resulted in a doubling of bacterial growth efficiency (BGE), whereas additions of DOCphyto or combined additions of DOCphyto and light had no effect on BGE. The change in BGE was not accompanied by shifts in the phylogenetic structure of the BCC, but BCC was influenced by the DOC source. Our results highlight that a doubling of BGE is not necessarily accompanied by a shift in BCC and that BCC is more strongly affected by resource properties. KW - Bacterial growth efficiency KW - Continuous cultures KW - Carbon decomposition KW - Leaf litter KW - Photolysis Y1 - 2015 U6 - https://doi.org/10.1007/s00248-014-0549-4 SN - 0095-3628 SN - 1432-184X VL - 69 IS - 2 SP - 361 EP - 371 PB - Springer CY - New York ER -