TY - JOUR A1 - Giling, Darren P. A1 - Nejstgaard, Jens C. A1 - Berger, Stella A. A1 - Grossart, Hans-Peter A1 - Kirillin, Georgiy A1 - Penske, Armin A1 - Lentz, Maren A1 - Casper, Peter A1 - Sareyka, Joerg A1 - Gessner, Mark O. T1 - Thermocline deepening boosts ecosystem metabolism: evidence from a large-scale lake enclosure experiment simulating a summer storm JF - Global change biology N2 - Extreme weather events can pervasively influence ecosystems. Observations in lakes indicate that severe storms in particular can have pronounced ecosystem-scale consequences, but the underlying mechanisms have not been rigorously assessed in experiments. One major effect of storms on lakes is the redistribution of mineral resources and plankton communities as a result of abrupt thermocline deepening. We aimed at elucidating the importance of this effect by mimicking in replicated large enclosures (each 9 m in diameter, ca. 20 m deep, ca. 1300 m 3 in volume) a mixing event caused by a severe natural storm that was previously observed in a deep clear-water lake. Metabolic rates were derived from diel changes in vertical profiles of dissolved oxygen concentrations using a Bayesian modelling approach, based on high-frequency measurements. Experimental thermocline deepening stimulated daily gross primary production (GPP) in surface waters by an average of 63% for > 4 weeks even though thermal stratification re-established within 5 days. Ecosystem respiration (ER) was tightly coupled to GPP, exceeding that in control enclosures by 53% over the same period. As GPP responded more strongly than ER, net ecosystem productivity (NEP) of the entire water column was also increased. These protracted increases in ecosystem metabolism and autotrophy were driven by a proliferation of inedible filamentous cyanobacteria released from light and nutrient limitation after they were entrained from below the thermocline into the surface water. Thus, thermocline deepening by a single severe storm can induce prolonged responses of lake ecosystem metabolism independent of other storm-induced effects, such as inputs of terrestrial materials by increased catchment run-off. This highlights that future shifts in frequency, severity or timing of storms are an important component of climate change, whose impacts on lake thermal structure will superimpose upon climate trends to influence algal dynamics and organic matter cycling in clear-water lakes. Keywords: climate variability, ecosystem productivity, extreme events, gross primary production, mesocosm, respiration stratified lakes KW - climate variability KW - ecosystem productivity KW - extreme events KW - gross primary production KW - mesocosm KW - respiration stratified lakes Y1 - 2017 U6 - https://doi.org/10.1111/gcb.13512 SN - 1354-1013 SN - 1365-2486 VL - 23 SP - 1448 EP - 1462 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Garcia, Sarahi L. A1 - McMahon, Katherine D. A1 - Grossart, Hans-Peter A1 - Warnecke, Falk T1 - Successful enrichment of the ubiquitous freshwater acI Actinobacteria JF - Environmental microbiology reports N2 - Actinobacteria of the acI lineage are often the numerically dominant bacterial phylum in surface freshwaters, where they can account for >50% of total bacteria. Despite their abundance, there are no described isolates. In an effort to obtain enrichment of these ubiquitous freshwater Actinobacteria, diluted freshwater samples from Lake Grosse Fuchskuhle, Germany, were incubated in 96-well culture plates. With this method, a successful enrichment containing high abundances of a member of the lineage acI was established. Phylogenetic classification showed that the acIActinobacteria of the enrichment belonged to the acI-B2 tribe, which seems to prefer acidic lakes. This enrichment grows to low cell densities and thus the oligotrophic nature of acI-B2 was confirmed. Y1 - 2014 U6 - https://doi.org/10.1111/1758-2229.12104 SN - 1758-2229 VL - 6 IS - 1 SP - 21 EP - 27 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Garcia, Sarahi L. A1 - Buck, Moritz A1 - McMahon, Katherine D. A1 - Grossart, Hans-Peter A1 - Eiler, Alexander A1 - Warnecke, Falk T1 - Auxotrophy and intrapopulation complementary in the "interactome' of a cultivated freshwater model community JF - Molecular ecology N2 - Microorganisms are usually studied either in highly complex natural communities or in isolation as monoclonal model populations that we manage to grow in the laboratory. Here, we uncover the biology of some of the most common and yet-uncultured bacteria in freshwater environments using a mixed culture from Lake Grosse Fuchskuhle. From a single shotgun metagenome of a freshwater mixed culture of low complexity, we recovered four high-quality metagenome-assembled genomes (MAGs) for metabolic reconstruction. This analysis revealed the metabolic interconnectedness and niche partitioning of these naturally dominant bacteria. In particular, vitamin- and amino acid biosynthetic pathways were distributed unequally with a member of Crenarchaeota most likely being the sole producer of vitamin B12 in the mixed culture. Using coverage-based partitioning of the genes recovered from a single MAG intrapopulation metabolic complementarity was revealed pointing to social' interactions for the common good of populations dominating freshwater plankton. As such, our MAGs highlight the power of mixed cultures to extract naturally occurring interactomes' and to overcome our inability to isolate and grow the microbes dominating in nature. KW - community KW - cultures KW - interactions KW - metagenomics KW - populations Y1 - 2015 U6 - https://doi.org/10.1111/mec.13319 SN - 0962-1083 SN - 1365-294X VL - 24 IS - 17 SP - 4449 EP - 4459 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Garcia, Sarahi L. A1 - Buck, Moritz A1 - Hamilton, Joshua J. A1 - Wurzbacher, Christian A1 - Grossart, Hans-Peter A1 - McMahon, Katherine D. A1 - Eiler, Alexander T1 - Model communities hint at promiscuous metabolic linkages between ubiquitous free-living freshwater bacteria JF - mSphere N2 - Genome streamlining is frequently observed in free-living aquatic microorganisms and results in physiological dependencies between microorganisms. However, we know little about the specificity of these microbial associations. In order to examine the specificity and extent of these associations, we established mixed cultures from three different freshwater environments and analyzed the cooccurrence of organisms using a metagenomic time series. Free-living microorganisms with streamlined genomes lacking multiple biosynthetic pathways showed no clear recurring pattern in their interaction partners. Free-living freshwater bacteria form promiscuous cooperative associations. This notion contrasts with the well-documented high specificities of interaction partners in host-associated bacteria. Considering all data together, we suggest that highly abundant free-living bacterial lineages are functionally versatile in their interactions despite their distinct streamlining tendencies at the single-cell level. This metabolic versatility facilitates interactions with a variable set of community members. KW - community KW - interactions KW - metagenomics KW - microbial ecology KW - mixed cultures KW - promiscuous Y1 - 2018 U6 - https://doi.org/10.1128/mSphere.00202-18 SN - 2379-5042 VL - 3 IS - 3 PB - American Society for Microbiology CY - Washington 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 - Frindte, Katharina A1 - Allgaier, Martin A1 - Grossart, Hans-Peter A1 - Eckert, Werner T1 - Microbial response to experimentally controlled redox transitions at the sediment water interface JF - PLoS one N2 - The sediment-water interface of freshwater lakes is characterized by sharp chemical gradients, shaped by the interplay between physical, chemical and microbial processes. As dissolved oxygen is depleted in the uppermost sediment, the availability of alternative electron acceptors, e.g. nitrate and sulfate, becomes the limiting factor. We performed a time series experiment in a mesocosm to simulate the transition from aerobic to anaerobic conditions at the sediment-water interface. Our goal was to identify changes in the microbial activity due to redox transitions induced by successive depletion of available electron acceptors. Monitoring critical hydrochemical parameters in the overlying water in conjunction with a new sampling strategy for sediment bacteria enabled us to correlate redox changes in the water to shifts in the active microbial community and the expression of functional genes representing specific redox-dependent microbial processes. Our results show that during several transitions from oxic-heterotrophic condition to sulfate-reducing condition, nitrate-availability and the on-set of sulfate reduction strongly affected the corresponding functional gene expression. There was evidence of anaerobic methane oxidation with NOx. DGGE analysis revealed redox-related changes in microbial activity and expression of functional genes involved in sulfate and nitrite reduction, whereas methanogenesis and methanotrophy showed only minor changes during redox transitions. The combination of high-frequency chemical measurements and molecular methods provide new insights into the temporal dynamics of the interplay between microbial activity and specific redox transitions at the sediment-water interface. Y1 - 2015 U6 - https://doi.org/10.1371/journal.pone.0143428 SN - 1932-6203 VL - 10 IS - 11 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Ferrera, Isabel A1 - Sarmento, Hugo A1 - Priscu, John C. A1 - Chiuchiolo, Amy A1 - Gonzalez, Jose M. A1 - Grossart, Hans-Peter T1 - Diversity and Distribution of Freshwater Aerobic Anoxygenic Phototrophic Bacteria across a Wide Latitudinal Gradient JF - Frontiers in microbiology N2 - Aerobic anoxygenic phototrophs (AAPs) have been shown to exist in numerous marine and brackish environments where they are hypothesized to play important ecological roles. Despite their potential significance, the study of freshwater AAPs is in its infancy and limited to local investigations. Here, we explore the occurrence, diversity and distribution of AAPs in lakes covering a wide latitudinal gradient: Mongolian and German lakes located in temperate regions of Eurasia, tropical Great East African lakes, and polar permanently ice-covered Antarctic lakes. Our results show a widespread distribution of AAPs in lakes with contrasting environmental conditions and confirm that this group is composed of different members of the Alpha- and Betaproteobacteria. While latitude does not seem to strongly influence AAP abundance, clear patterns of community structure and composition along geographic regions were observed as indicated by a strong macro-geographical signal in the taxonomical composition of AAPs. Overall, our results suggest that the distribution patterns of freshwater AAPs are likely driven by a combination of small-scale environmental conditions (specific of each lake and region) and large-scale geographic factors (climatic regions across a latitudinal gradient). KW - AAP bacteria KW - photoheterotrophy KW - pufM gene KW - freshwater lakes KW - latitudinal gradients KW - biogeography Y1 - 2017 U6 - https://doi.org/10.3389/fmicb.2017.00175 SN - 1664-302X VL - 8 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Fasching, Christina A1 - Akotoye, Christian A1 - Bižić, Mina A1 - Fonvielle, Jeremy Andre A1 - Ionescu, Danny A1 - Mathavarajah, Sabateeshan A1 - Zoccarato, Luca A1 - Walsh, David A. A1 - Grossart, Hans-Peter A1 - Xenopoulos, Marguerite A. T1 - Linking stream microbial community functional genes to dissolved organic matter and inorganic nutrients JF - Limnology and oceanography N2 - There is now increasing evidence for the importance of microbial regulation of biogeochemical cycling in streams. Resource availability shapes microbial community structure, but less is known about how landscape-mediated availability of nutrients and carbon can control microbial functions in streams. Using comparative metagenomics, we examined the relationship between microbial functional genes and composition of dissolved organic matter (DOM), nutrients, and suspended microbial communities in 11 streams, divided into three groups based on the predominant land cover category (agriculture, forested, or wetland). Using weighted gene co-occurrence network analysis, we identified clusters of functions related to DOM composition, agricultural land use, and/or wetland and forest land cover. Wetland-dominated streams were characterized by functions related to nitrogen metabolism and processing of aromatic carbon compounds, with strong positive correlations with dissolved organic carbon concentration and DOM aromaticity. Forested streams were characterized by metabolic functions related to monomer uptake and carbohydrates, such as mannose and fructose metabolism. In agricultural streams, microbial functions were correlated with more labile, protein-like DOM, PO4, and NO3, likely reflecting functional adaptation to labile DOM and higher nutrient concentrations. Distinct changes in the functional composition and loss of functional diversity of microorganisms became evident when comparing natural to agricultural catchments. Although all streams showed signs of functional redundancy, loss of species richness per function in agricultural catchments suggests that microbial functions in natural catchments may be more resilient to disturbance. Our results provide new insight into microbial community functions involved in nutrient and carbon biogeochemical cycles and their dependence on specific environmental settings. Y1 - 2019 U6 - https://doi.org/10.1002/lno.11356 SN - 0024-3590 SN - 1939-5590 VL - 65 SP - S71 EP - S87 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Engel, Anja A1 - Piontek, Judith A1 - Grossart, Hans-Peter A1 - Riebesell, Ulf A1 - Schulz, Kai Georg A1 - Sperling, Martin T1 - Impact of CO2 enrichment on organic matter dynamics during nutrient induced coastal phytoplankton blooms JF - Journal of plankton research N2 - A mesocosm experiment was conducted to investigate the impact of rising fCO(2) on the build-up and decline of organic matter during coastal phytoplankton blooms. Five mesocosms (similar to 38 mA(3) each) were deployed in the Baltic Sea during spring (2009) and enriched with CO2 to yield a gradient of 355-862 A mu atm. Mesocosms were nutrient fertilized initially to induce phytoplankton bloom development. Changes in particulate and dissolved organic matter concentrations, including dissolved high-molecular weight (> 1 kDa) combined carbohydrates, dissolved free and combined amino acids as well as transparent exopolymer particles (TEP), were monitored over 21 days together with bacterial abundance, and hydrolytic extracellular enzyme activities. Overall, organic matter followed well-known bloom dynamics in all CO2 treatments alike. At high fCO(2,) higher Delta POC:Delta PON during bloom rise, and higher TEP concentrations during bloom peak, suggested preferential accumulation of carbon-rich components. TEP concentration at bloom peak was significantly related to subsequent sedimentation of particulate organic matter. Bacterial abundance increased during the bloom and was highest at high fCO(2). We conclude that increasing fCO(2) supports production and exudation of carbon-rich components, enhancing particle aggregation and settling, but also providing substrate and attachment sites for bacteria. More labile organic carbon and higher bacterial abundance can increase rates of oxygen consumption and may intensify the already high risk of oxygen depletion in coastal seas in the future. KW - mesocosm KW - ocean acidification KW - phytoplankton KW - organic matter KW - TEP Y1 - 2014 U6 - https://doi.org/10.1093/plankt/fbt125 SN - 0142-7873 SN - 1464-3774 VL - 36 IS - 3 SP - 641 EP - 657 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Eigemann, Falk A1 - Hilt, Sabine A1 - Salka, Ivette A1 - Grossart, Hans-Peter T1 - Bacterial community composition associated with freshwater algae species specificity vs. dependency on environmental conditions and source community JF - FEMS microbiology ecology N2 - We studied bacterial associations with the green alga Desmodesmus armatus and the diatom Stephanodiscus minutulus under changing environmental conditions and bacterial source communities, to evaluate whether bacteriaalgae associations are species-specific or more generalized and determined by external factors. Axenic and xenic algae were incubated in situ with and without allelopathically active macrophytes, and in the laboratory with sterile and nonsterile lake water and an allelochemical, tannic acid (TA). Bacterial community composition (BCC) of algae-associated bacteria was analyzed by denaturing gradient gel electrophoresis (DGGE), nonmetric multidimensional scaling, cluster analyses, and sequencing of DGGE bands. BCC of xenic algal cultures of both species were not significantly affected by changes in their environment or bacterial source community, except in the case of TA additions. Species-specific interactions therefore appear to overrule the effects of environmental conditions and source communities. The BCC of xenic and axenic D.armatus cultures subjected to in situ bacterial colonization, however, had lower similarities (ca.55%), indicating that bacterial precolonization is a strong factor for bacteriaalgae associations irrespective of environmental conditions and source community. Our findings emphasize the ecological importance of species-specific bacteriaalgae associations with important repercussions for other processes, such as the remineralization of nutrients, and organic matter dynamics. KW - allelopathy KW - bacteriaalgae associations KW - heterotrophic bacteria KW - species-specific Y1 - 2013 U6 - https://doi.org/10.1111/1574-6941.12022 SN - 0168-6496 VL - 83 IS - 3 SP - 650 EP - 663 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Eckert, Ester M. A1 - Di Cesare, Andrea A1 - Kettner, Marie Therese A1 - Arias-Andres, Maria A1 - Fontaneto, Diego A1 - Grossart, Hans-Peter A1 - Corno, Gianluca T1 - Microplastics increase impact of treated wastewater on freshwater microbial community JF - Environmental pollution N2 - Plastic pollution is a major global concern with several million microplastic particles entering every day freshwater ecosystems via wastewater discharge. Microplastic particles stimulate biofilm formation (plastisphere) throughout the water column and have the potential to affect microbial community structure if they accumulate in pelagic waters, especially enhancing the proliferation of biohazardous bacteria. To test this scenario, we simulated the inflow of treated wastewater into a temperate lake using a continuous culture system with a gradient of concentration of microplastic particles. We followed the effect of microplastics on the microbial community structure and on the occurrence of integrase 1 (intl), a marker associated with mobile genetic elements known as a proxy for anthropogenic effects on the spread of antimicrobial resistance genes. The abundance of intl increased in the plastisphere with increasing microplastic particle concentration, but not in the water surrounding the microplastic particles. Likewise, the microbial community on microplastic was more similar to the original wastewater community with increasing microplastic concentrations. Our results show that microplastic particles indeed promote persistence of typical indicators of microbial anthropogenic pollution in natural waters, and substantiate that their removal from treated wastewater should be prioritised. (C) 2017 Elsevier Ltd. All rights reserved. KW - Microplastics KW - Anthropogenic pollution KW - Treated wastewater KW - Freshwater microbial communities KW - Integrase 1 KW - Biofilm Y1 - 2017 U6 - https://doi.org/10.1016/j.envpol.2017.11.070 SN - 0269-7491 SN - 1873-6424 VL - 234 SP - 495 EP - 502 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Dziallas, Claudia A1 - Grossart, Hans-Peter T1 - Microbial interactions with the cyanobacterium Microcystis aeruginosa and their dependence on temperature JF - Marine biology : international journal on life in oceans and coastal waters N2 - Associated heterotrophic bacteria alter the microenvironment of cyanobacteria and potentially influence cyanobacterial development. Therefore, we studied interactions of the unicellular freshwater cyanobacterium Microcystis aeruginosa with heterotrophic bacteria. The associated bacterial community was greatly driven by temperature as seen by DNA fingerprinting. However, the associated microbes also closely interacted with the cyanobacteria indicating changing ecological consequence of the associated bacterial community with temperature. Whereas concentration of dissolved organic carbon in cyanobacterial cultures changed in a temperature-dependent manner, its quality greatly varied under the same environmental conditions, but with different associated bacterial communities. Furthermore, temperature affected quantity and quality of cell-bound microcystins, whereby interactions between M. aeruginosa and their associated community often masked this temperature effect. Both macro- and microenvironment of active cyanobacterial strains were characterized by high pH and oxygen values creating a unique habitat that potentially affects microbial diversity and function. For example, archaea including 'anaerobic' methanogens contributed to the associated microbial community. This implies so far uncharacterized interactions between Microcystis aeruginosa and its associated prokaryotic community, which has unknown ecological consequences in a climatically changing world. Y1 - 2012 U6 - https://doi.org/10.1007/s00227-012-1927-4 SN - 0025-3162 VL - 159 IS - 11 SP - 2389 EP - 2398 PB - Springer CY - New York ER - TY - JOUR A1 - Dubovskaya, Olga P. A1 - Tang, Kam W. A1 - Gladyshev, Michail I. A1 - Kirillin, Georgiy A1 - Buseva, Zhanna A1 - Kasprzak, Peter A1 - Tolomeev, Aleksandr P. A1 - Grossart, Hans-Peter T1 - Estimating In Situ Zooplankton Non-Predation Mortality in an Oligo-Mesotrophic Lake from Sediment Trap Data: Caveats and Reality Check JF - PLoS one N2 - Background Mortality is a main driver in zooplankton population biology but it is poorly constrained in models that describe zooplankton population dynamics, food web interactions and nutrient dynamics. Mortality due to non-predation factors is often ignored even though anecdotal evidence of non-predation mass mortality of zooplankton has been reported repeatedly. One way to estimate non-predation mortality rate is to measure the removal rate of carcasses, for which sinking is the primary removal mechanism especially in quiescent shallow water bodies. Objectives and Results We used sediment traps to quantify in situ carcass sinking velocity and non-predation mortality rate on eight consecutive days in 2013 for the cladoceran Bosmina longirostris in the oligo-mesotrophic Lake Stechlin; the outcomes were compared against estimates derived from in vitro carcass sinking velocity measurements and an empirical model correcting in vitro sinking velocity for turbulence resuspension and microbial decomposition of carcasses. Our results show that the latter two approaches produced unrealistically high mortality rates of 0.58-1.04 d(-1), whereas the sediment trap approach, when used properly, yielded a mortality rate estimate of 0.015 d(-1), which is more consistent with concurrent population abundance data and comparable to physiological death rate from the literature. Ecological implications Zooplankton carcasses may be exposed to water column microbes for days before entering the benthos; therefore, non-predation mortality affects not only zooplankton population dynamics but also microbial and benthic food webs. This would be particularly important for carbon and nitrogen cycles in systems where recurring mid-summer decline of zooplankton population due to non-predation mortality is observed. Y1 - 2015 U6 - https://doi.org/10.1371/journal.pone.0131431 SN - 1932-6203 VL - 10 IS - 7 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Darwall, William A1 - Bremerich, Vanessa A1 - De Wever, Aaike A1 - Dell, Anthony I. A1 - Freyhof, Joerg A1 - Gessner, Mark O. A1 - Grossart, Hans-Peter A1 - Harrison, Ian A1 - Irvine, Ken A1 - Jähnig, Sonja C. A1 - Jeschke, Jonathan M. A1 - Lee, Jessica J. A1 - Lu, Cai A1 - Lewandowska, Aleksandra M. A1 - Monaghan, Michael T. A1 - Nejstgaard, Jens C. A1 - Patricio, Harmony A1 - Schmidt-Kloiber, Astrid A1 - Stuart, Simon N. A1 - Thieme, Michele A1 - Tockner, Klement A1 - Turak, Eren A1 - Weyl, Olaf T1 - The alliance for freshwater life BT - a global call to unite efforts for freshwater biodiversity science and conservation JF - Aquatic Conservation: Marine and Freshwater Ecosystems N2 - 1. Global pressures on freshwater ecosystems are high and rising. Viewed primarily as a resource for humans, current practices of water use have led to catastrophic declines in freshwater species and the degradation of freshwater ecosystems, including their genetic and functional diversity. Approximately three-quarters of the world's inland wetlands have been lost, one-third of the 28 000 freshwater species assessed for the International Union for Conservation of Nature (IUCN) Red List are threatened with extinction, and freshwater vertebrate populations are undergoing declines that are more rapid than those of terrestrial and marine species. This global loss continues unchecked, despite the importance of freshwater ecosystems as a source of clean water, food, livelihoods, recreation, and inspiration. 2. The causes of these declines include hydrological alterations, habitat degradation and loss, overexploitation, invasive species, pollution, and the multiple impacts of climate change. Although there are policy initiatives that aim to protect freshwater life, these are rarely implemented with sufficient conviction and enforcement. Policies that focus on the development and management of fresh waters as a resource for people almost universally neglect the biodiversity that they contain. 3. Here we introduce the Alliance for Freshwater Life, a global initiative, uniting specialists in research, data synthesis, conservation, education and outreach, and policymaking. This expert network aims to provide the critical mass required for the effective representation of freshwater biodiversity at policy meetings, to develop solutions balancing the needs of development and conservation, and to better convey the important role freshwater ecosystems play in human well-being. Through this united effort we hope to reverse this tide of loss and decline in freshwater biodiversity. We introduce several short- and medium-term actions as examples for making positive change, and invite individuals, organizations, authorities, and governments to join the Alliance for Freshwater Life. KW - biodiversity KW - conservation evaluation KW - endangered species KW - fish KW - invertebrates KW - macrophytes Y1 - 2018 U6 - https://doi.org/10.1002/aqc.2958 SN - 1052-7613 SN - 1099-0755 VL - 28 IS - 4 SP - 1015 EP - 1022 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Cuadrat, Rafael R. C. A1 - Ionescu, Danny A1 - Davila, Alberto M. R. A1 - Grossart, Hans-Peter T1 - Recovering genomics clusters of secondary metabolites from lakes using genome-resolved metagenomics JF - Frontiers in microbiology N2 - Metagenomic approaches became increasingly popular in the past decades due to decreasing costs of DNA sequencing and bioinformatics development. So far, however, the recovery of long genes coding for secondary metabolites still represents a big challenge. Often, the quality of metagenome assemblies is poor, especially in environments with a high microbial diversity where sequence coverage is low and complexity of natural communities high. Recently, new and improved algorithms for binning environmental reads and contigs have been developed to overcome such limitations. Some of these algorithms use a similarity detection approach to classify the obtained reads into taxonomical units and to assemble draft genomes. This approach, however, is quite limited since it can classify exclusively sequences similar to those available (and well classified) in the databases. In this work, we used draft genomes from Lake Stechlin, north-eastern Germany, recovered by MetaBat, an efficient binning tool that integrates empirical probabilistic distances of genome abundance, and tetranucleotide frequency for accurate metagenome binning. These genomes were screened for secondary metabolism genes, such as polyketide synthases (PKS) and non-ribosomal peptide synthases (NRPS), using the Anti-SMASH and NAPDOS workflows. With this approach we were able to identify 243 secondary metabolite clusters from 121 genomes recovered from our lake samples. A total of 18 NRPS, 19 PKS, and 3 hybrid PKS/NRPS clusters were found. In addition, it was possible to predict the partial structure of several secondary metabolite clusters allowing for taxonomical classifications and phylogenetic inferences. Our approach revealed a high potential to recover and study secondary metabolites genes from any aquatic ecosystem. KW - metagenomics 2.0 KW - PKS KW - NRPS KW - freshwater KW - environmental genomics Y1 - 2018 U6 - https://doi.org/10.3389/fmicb.2018.00251 SN - 1664-302X VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Corno, Gianluca A1 - Salka, Ivette A1 - Pohlmann, Kirsten A1 - Hall, Alex R. A1 - Grossart, Hans-Peter T1 - Interspecific interactions drive chitin and cellulose degradation by aquatic microorganisms JF - Aquatic microbial ecology : international journal N2 - Complex biopolymers (BPs) such as chitin and cellulose provide the majority of organic carbon in aquatic ecosystems, but the mechanisms by which communities of bacteria in natural systems exploit them are unclear. Previous degradation experiments in artificial systems predominantly used microcosms containing a single bacterial species, neglecting effects of interspecific interactions. By constructing simplified aquatic microbial communities, we tested how the addition of other bacterial species, of a nanoflagellate protist capable of consuming bacteria, or of both, affect utilization of BPs. Surprisingly, total abundance of resident bacteria in mixed communities increased upon addition of the protist. Concomitantly, bacteria shifted from free-living to aggregated morphotypes that seemed to promote utilization of BPs. In our model system, these interactions significantly increased productivity in terms of overall bacterial numbers and carbon transfer efficiency. This indicates that interactions on microbial aggregates may be crucial for chitin and cellulose degradation. We therefore suggest that interspecific microbial interactions must be considered when attempting to model the turnover of the vast pool of complex biopolymers in aquatic ecosystems. KW - Aggregation KW - Flagellate grazing KW - Ecological interactions KW - Microbial carbon transfer KW - Polymer degradation KW - System ecology Y1 - 2015 U6 - https://doi.org/10.3354/ame01765 SN - 0948-3055 SN - 1616-1564 VL - 76 IS - 1 SP - 27 EP - + PB - Institute of Mathematical Statistics CY - Oldendorf Luhe ER - TY - JOUR A1 - Cook, Katherine V. A1 - Li, Chuang A1 - Cai, Haiyuan A1 - Krumholz, Lee R. A1 - Hambright, K. David A1 - Paerl, Hans W. A1 - Steffen, Morgan M. A1 - Wilson, Alan E. A1 - Burford, Michele A. A1 - Grossart, Hans-Peter A1 - Hamilton, David P. A1 - Jiang, Helong A1 - Sukenik, Assaf A1 - Latour, Delphine A1 - Meyer, Elisabeth I. A1 - Padisak, Judit A1 - Qin, Boqiang A1 - Zamor, Richard M. A1 - Zhu, Guangwei T1 - The global Microcystis interactome JF - Limnology and oceanography N2 - Bacteria play key roles in the function and diversity of aquatic systems, but aside from study of specific bloom systems, little is known about the diversity or biogeography of bacteria associated with harmful cyanobacterial blooms (cyanoHABs). CyanoHAB species are known to shape bacterial community composition and to rely on functions provided by the associated bacteria, leading to the hypothesized cyanoHAB interactome, a coevolved community of synergistic and interacting bacteria species, each necessary for the success of the others. Here, we surveyed the microbiome associated with Microcystis aeruginosa during blooms in 12 lakes spanning four continents as an initial test of the hypothesized Microcystis interactome. We predicted that microbiome composition and functional potential would be similar across blooms globally. Our results, as revealed by 16S rRNA sequence similarity, indicate that M. aeruginosa is cosmopolitan in lakes across a 280 degrees longitudinal and 90 degrees latitudinal gradient. The microbiome communities were represented by a wide range of operational taxonomic units and relative abundances. Highly abundant taxa were more related and shared across most sites and did not vary with geographic distance, thus, like Microcystis, revealing no evidence for dispersal limitation. High phylogenetic relatedness, both within and across lakes, indicates that microbiome bacteria with similar functional potential were associated with all blooms. While Microcystis and the microbiome bacteria shared many genes, whole-community metagenomic analysis revealed a suite of biochemical pathways that could be considered complementary. Our results demonstrate a high degree of similarity across global Microcystis blooms, thereby providing initial support for the hypothesized Microcystis interactome. Y1 - 2019 U6 - https://doi.org/10.1002/lno.11361 SN - 0024-3590 SN - 1939-5590 VL - 65 SP - S194 EP - S207 PB - Wiley CY - Hoboken ER - TY - INPR A1 - Chattopadhyay, Madhab K. A1 - Chakraborty, Ranadhir A1 - Grossart, Hans-Peter A1 - Reddy, Gundlapally S. A1 - Jagannadham, Medicharla V. T1 - Antibiotic resistance of bacteria T2 - BioMed research international Y1 - 2015 U6 - https://doi.org/10.1155/2015/501658 SN - 2314-6133 SN - 2314-6141 PB - Hindawi Publishing Corp. CY - New York ER - TY - JOUR A1 - Cepakova, Zuzana A1 - Hrouzek, Pavel A1 - Ziskova, Eva A1 - Nuyanzina-Boldareva, Ekaterina A1 - Sorf, Michal A1 - Kozlikova-Zapomelova, Eliska A1 - Salka, Ivette A1 - Grossart, Hans-Peter A1 - Koblizek, Michal T1 - High turnover rates of aerobic anoxygenic phototrophs in European freshwater lakes JF - Environmental microbiology N2 - Aerobic Anoxygenic Phototrophic (AAP) bacteria are bacteriochlorophyll (BChl) a -containing organisms which use light energy to supplement their predominantly heterotrophic metabolism. Here, we investigated mortality and growth rates of AAP bacteria in three different freshwater lakes in Central Europe: the mountain lake Plesne, the oligo-mesotrophic Lake Stechlin and the forest pond Huntov. The mortality of AAP bacteria was estimated from diel changes of BChl a fluorescence. Net and gross growth rates were calculated from the increases in AAP cell numbers. The gross growth rates of AAP bacteria ranged from 0.38 to 5.6 d(-1), with the highest values observed during summer months. Simultaneously, the rapidly growing AAP cells have to cope with an intense grazing pressure by both zooplankton and protists. The presented results document that during the day, gross growth usually surpased mortality. Our results indicate that AAP bacteria utilize light energy under natural conditions to maintain rapid growth rates, which are balanced by a generally intense grazing pressure. Y1 - 2016 U6 - https://doi.org/10.1111/1462-2920.13475 SN - 1462-2912 SN - 1462-2920 VL - 18 SP - 5063 EP - 5071 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Bálint, Miklós A1 - Pfenninger, Markus A1 - Grossart, Hans-Peter A1 - Taberlet, Pierre A1 - Vellend, Mark A1 - Leibold, Mathew A. A1 - Englund, Goran A1 - Bowler, Diana T1 - Environmental DNA time series in ecology JF - Trends in ecology & evolution N2 - Ecological communities change in time and space, but long-term dynamics at the century-to-millennia scale are poorly documented due to lack of relevant data sets. Nevertheless, understanding long-term dynamics is important for explaining present-day biodiversity patterns and placing conservation goals in a historical context. Here, we use recent examples and new perspectives to highlight how environmental DNA (eDNA) is starting to provide a powerful new source of temporal data for research questions that have so far been overlooked, by helping to resolve the ecological dynamics of populations, communities, and ecosystems over hundreds to thousands of years. We give examples of hypotheses that may be addressed by temporal eDNA biodiversity data, discuss possible research directions, and outline related challenges. Y1 - 2018 U6 - https://doi.org/10.1016/j.tree.2018.09.003 SN - 0169-5347 SN - 1872-8383 VL - 33 IS - 12 SP - 945 EP - 957 PB - Elsevier CY - London ER - TY - JOUR A1 - Brothers, Soren M. A1 - Koehler, J. A1 - Attermeyer, Katrin A1 - Grossart, Hans-Peter A1 - Mehner, T. A1 - Meyer, N. A1 - Scharnweber, Inga Kristin A1 - Hilt, Sabine T1 - A feedback loop links brownification and anoxia in a temperate, shallow lake JF - Limnology and oceanography N2 - This study examines a natural, rapid, fivefold increase in dissolved organic carbon (DOC) concentrations in a temperate shallow lake, describing the processes by which increased DOC resulted in anoxic conditions and altered existing carbon cycling pathways. High precipitation for two consecutive years led to rising water levels and the flooding of adjacent degraded peatlands. Leaching from the flooded soils provided an initial increase in DOC concentrations (from a 2010 mean of 12 +/- 1 mg L-1 to a maximum concentration of 53 mg L-1 by June 2012). Increasing water levels, DOC, and phytoplankton concentrations reduced light reaching the sediment surface, eliminating most benthic primary production and promoting anoxia in the hypolimnion. From January to June 2012 there was a sudden increase in total phosphorus (from 57 mg L-1 to 216 mg L-1), DOC (from 24.6 mg L-1 to 53 mg L-1), and iron (from 0.12 mg L-1 to 1.07 mg L-1) concentrations, without any further large fluxes in water levels. We suggest that anoxic conditions at the sediment surface and flooded soils produced a dramatic release of these chemicals that exacerbated brownification and eutrophication, creating anoxic conditions that persisted roughly 6 months below a water depth of 1 m and extended periodically to the water surface. This brownification-anoxia feedback loop resulted in a near-complete loss of macroinvertebrate and fish populations, and increased surface carbon dioxide (CO2) emissions by an order of magnitude relative to previous years. Y1 - 2014 U6 - https://doi.org/10.4319/lo.2014.59.4.1388 SN - 0024-3590 SN - 1939-5590 VL - 59 IS - 4 SP - 1388 EP - 1398 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Brothers, Soren M. A1 - Hilt, Sabine A1 - Attermeyer, Katrin A1 - Grossart, Hans-Peter A1 - Kosten, Sarian A1 - Lischke, Betty A1 - Mehner, Thomas A1 - Meyer, Nils A1 - Scharnweber, Inga Kristin A1 - Köhler, Jan T1 - A regime shift from macrophyte to phytoplankton dominance enhances carbon burial in a shallow, eutrophic lake JF - Ecosphere : the magazine of the International Ecology University N2 - Ecological regime shifts and carbon cycling in aquatic systems have both been subject to increasing attention in recent years, yet the direct connection between these topics has remained poorly understood. A four-fold increase in sedimentation rates was observed within the past 50 years in a shallow eutrophic lake with no surface in-or outflows. This change coincided with an ecological regime shift involving the complete loss of submerged macrophytes, leading to a more turbid, phytoplankton-dominated state. To determine whether the increase in carbon (C) burial resulted from a comprehensive transformation of C cycling pathways in parallel to this regime shift, we compared the annual C balances (mass balance and ecosystem budget) of this turbid lake to a similar nearby lake with submerged macrophytes, a higher transparency, and similar nutrient concentrations. C balances indicated that roughly 80% of the C input was permanently buried in the turbid lake sediments, compared to 40% in the clearer macrophyte-dominated lake. This was due to a higher measured C burial efficiency in the turbid lake, which could be explained by lower benthic C mineralization rates. These lower mineralization rates were associated with a decrease in benthic oxygen availability coinciding with the loss of submerged macrophytes. In contrast to previous assumptions that a regime shift to phytoplankton dominance decreases lake heterotrophy by boosting whole-lake primary production, our results suggest that an equivalent net metabolic shift may also result from lower C mineralization rates in a shallow, turbid lake. The widespread occurrence of such shifts may thus fundamentally alter the role of shallow lakes in the global C cycle, away from channeling terrestrial C to the atmosphere and towards burying an increasing amount of C. KW - calcite precipitation KW - CO2 emissions KW - global carbon cycle KW - metabolism KW - regime shift KW - sedimentation KW - submerged macrophytes KW - temperate zone KW - trophic status Y1 - 2013 U6 - https://doi.org/10.1890/ES13-00247.1 SN - 2150-8925 VL - 4 IS - 11 PB - Wiley CY - Washington ER - TY - JOUR A1 - Block, Benjamin D. A1 - Denfeld, Blaize A. A1 - Stockwell, Jason D. A1 - Flaim, Giovanna A1 - Grossart, Hans-Peter A1 - Knoll, Lesley B. A1 - Maier, Dominique B. A1 - North, Rebecca L. A1 - Rautio, Milla A1 - Rusak, James A. A1 - Sadro, Steve A1 - Weyhenmeyer, Gesa A. A1 - Bramburger, Andrew J. A1 - Branstrator, Donn K. A1 - Salonen, Kalevi A1 - Hampton, Stephanie E. T1 - The unique methodological challenges of winter limnology JF - Limnology and Oceanography: Methods N2 - Winter is an important season for many limnological processes, which can range from biogeochemical transformations to ecological interactions. Interest in the structure and function of lake ecosystems under ice is on the rise. Although limnologists working at polar latitudes have a long history of winter work, the required knowledge to successfully sample under winter conditions is not widely available and relatively few limnologists receive formal training. In particular, the deployment and operation of equipment in below 0 degrees C temperatures pose considerable logistical and methodological challenges, as do the safety risks of sampling during the ice-covered period. Here, we consolidate information on winter lake sampling and describe effective methods to measure physical, chemical, and biological variables in and under ice. We describe variation in snow and ice conditions and discuss implications for sampling logistics and safety. We outline commonly encountered methodological challenges and make recommendations for best practices to maximize safety and efficiency when sampling through ice or deploying instruments in ice-covered lakes. Application of such practices over a broad range of ice-covered lakes will contribute to a better understanding of the factors that regulate lakes during winter and how winter conditions affect the subsequent ice-free period. Y1 - 2018 U6 - https://doi.org/10.1002/lom3.10295 SN - 1541-5856 VL - 17 IS - 1 SP - 42 EP - 57 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Bizic-Ionescu, Mina A1 - Zeder, Michael A1 - Ionescu, Danny A1 - Orlic, Sandi A1 - Fuchs, Bernhard M. A1 - Grossart, Hans-Peter A1 - Amann, Rudolf T1 - Comparison of bacterial communities on limnic versus coastal marine particles reveals profound differences in colonization JF - Environmental microbiology N2 - Marine and limnic particles are hotspots of organic matter mineralization significantly affecting biogeochemical element cycling. Fluorescence in-situ hybridization and pyrosequencing of 16S rRNA genes were combined to investigate bacterial diversity and community composition on limnic and coastal marine particles >5 and >10m respectively. Limnic particles were more abundant (average: 1x10(7)l(-1)), smaller in size (average areas: 471 versus 2050m(2)) and more densely colonized (average densities: 7.3 versus 3.6 cells 100m(-2)) than marine ones. Limnic particle-associated (PA) bacteria harboured Alphaproteobacteria and Betaproteobacteria, and unlike previously suggested sizeable populations of Gammaproteobacteria, Actinobacteria and Bacteroidetes. Marine particles were colonized by Planctomycetes and Betaproteobacteria additionally to Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria. Large differences in individual particle colonization could be detected. High-throughput sequencing revealed a significant overlap of PA and free-living (FL) bacteria highlighting an underestimated connectivity between both fractions. PA bacteria were in 14/21 cases more diverse than FL bacteria, reflecting a high heterogeneity in the particle microenvironment. We propose that a ratio of Chao 1 indices of PA/FL<1 indicates the presence of rather homogeneously colonized particles. The identification of different bacterial families enriched on either limnic or marine particles demonstrates that, despite the seemingly similar ecological niches, PA communities of both environments differ substantially. Y1 - 2015 U6 - https://doi.org/10.1111/1462-2920.12466 SN - 1462-2912 SN - 1462-2920 VL - 17 IS - 10 SP - 3500 EP - 3514 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Bizic-Ionescu, Mina A1 - Ionescu, Danny A1 - Grossart, Hans-Peter T1 - Organic Particles: Heterogeneous Hubs for Microbial Interactions in Aquatic Ecosystems JF - Frontiers in microbiology N2 - The dynamics and activities of microbes colonizing organic particles (hereafter particles) greatly determine the efficiency of the aquatic carbon pump. Current understanding is that particle composition, structure and surface properties, determined mostly by the forming organisms and organic matter, dictate initial microbial colonization and the subsequent rapid succession events taking place as organic matter lability and nutrient content change with microbial degradation. We applied a transcriptomic approach to assess the role of stochastic events on initial microbial colonization of particles. Furthermore, we asked whether gene expression corroborates rapid changes in carbon-quality. Commonly used size fractionated filtration averages thousands of particles of different sizes, sources, and ages. To overcome this drawback, we used replicate samples consisting each of 3–4 particles of identical source and age and further evaluated the consequences of averaging 10–1000s of particles. Using flow-through rolling tanks we conducted long-term experiments at near in situ conditions minimizing the biasing effects of closed incubation approaches often referred to as “the bottle-effect.” In our open flow-through rolling tank system, however, active microbial communities were highly heterogeneous despite an identical particle source, suggesting random initial colonization. Contrasting previous reports using closed incubation systems, expression of carbon utilization genes didn’t change after 1 week of incubation. Consequently, we suggest that in nature, changes in particle-associated community related to carbon availability are much slower (days to weeks) due to constant supply of labile, easily degradable organic matter. Initial, random particle colonization seems to be subsequently altered by multiple organismic interactions shaping microbial community interactions and functional dynamics. Comparative analysis of thousands particles pooled togethers as well as pooled samples suggests that mechanistic studies of microbial dynamics should be done on single particles. The observed microbial heterogeneity and inter-organismic interactions may have important implications for evolution and biogeochemistry in aquatic systems. KW - particle-associated bacteria KW - microbial communities KW - inter- and intra-species interactions KW - antagonism KW - phage KW - transcriptome Y1 - 2018 U6 - https://doi.org/10.3389/fmicb.2018.02569 SN - 1664-302X VL - 9 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Bizic-Ionescu, Mina A1 - Amann, Rudolf A1 - Grossart, Hans-Peter T1 - Massive regime shifts and high activity of heterotrophic bacteria in an ice-covered lake JF - PLoS one N2 - In winter 2009/10, a sudden under-ice bloom of heterotrophic bacteria occurred in the seasonally ice-covered, temperate, deep, oligotrophic Lake Stechlin (Germany). Extraordinarily high bacterial abundance and biomass were fueled by the breakdown of a massive bloom of Aphanizomenon flos-aquae after ice formation. A reduction in light resulting from snow coverage exerted a pronounced physiological stress on the cyanobacteria. Consequently, these were rapidly colonized, leading to a sudden proliferation of attached and subsequently of free-living heterotrophic bacteria. Total bacterial protein production reached 201 mg C L-1 d(-1), ca. five times higher than spring-peak values that year. Fluorescence in situ hybridization and denaturing gradient gel electrophoresis at high temporal resolution showed pronounced changes in bacterial community structure coinciding with changes in the physiology of the cyanobacteria. Pyrosequencing of 16S rRNA genes revealed that during breakdown of the cyanobacterial population, the diversity of attached and free-living bacterial communities were reduced to a few dominant families. Some of these were not detectable during the early stages of the cyanobacterial bloom indicating that only specific, well adapted bacterial communities can colonize senescent cyanobacteria. Our study suggests that in winter, unlike commonly postulated, carbon rather than temperature is the limiting factor for bacterial growth. Frequent phytoplankton blooms in ice-covered systems highlight the need for year-round studies of aquatic ecosystems including the winter season to correctly understand element and energy cycling through aquatic food webs, particularly the microbial loop. On a global scale, such knowledge is required to determine climate change induced alterations in carbon budgets in polar and temperate aquatic systems. Y1 - 2014 U6 - https://doi.org/10.1371/journal.pone.0113611 SN - 1932-6203 VL - 9 IS - 11 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Bizic, Mina A1 - Ionescu, Danny A1 - Karnatak, Rajat A1 - Musseau, Camille L. A1 - Onandia, Gabriela A1 - Berger, Stella A. A1 - Nejstgaard, Jens C. A1 - Lischeid, Gunnar A1 - Gessner, Mark O. A1 - Wollrab, Sabine A1 - Grossart, Hans-Peter T1 - Land-use type temporarily affects active pond community structure but not gene expression patterns JF - Molecular ecology N2 - Changes in land use and agricultural intensification threaten biodiversity and ecosystem functioning of small water bodies. We studied 67 kettle holes (KH) in an agricultural landscape in northeastern Germany using landscape-scale metatranscriptomics to understand the responses of active bacterial, archaeal and eukaryotic communities to land-use type. These KH are proxies of the millions of small standing water bodies of glacial origin spread across the northern hemisphere. Like other landscapes in Europe, the study area has been used for intensive agriculture since the 1950s. In contrast to a parallel environmental DNA study that suggests the homogenization of biodiversity across KH, conceivably resulting from long-lasting intensive agriculture, land-use type affected the structure of the active KH communities during spring crop fertilization, but not a month later. This effect was more pronounced for eukaryotes than for bacteria. In contrast, gene expression patterns did not differ between months or across land-use types, suggesting a high degree of functional redundancy across the KH communities. Variability in gene expression was best explained by active bacterial and eukaryotic community structures, suggesting that these changes in functioning are primarily driven by interactions between organisms. Our results indicate that influences of the surrounding landscape result in temporary changes in the activity of different community members. Thus, even in KH where biodiversity has been homogenized, communities continue to respond to land management. This potential needs to be considered when developing sustainable management options for restoration purposes and for successful mitigation of further biodiversity loss in agricultural landscapes. KW - agriculture KW - eRNA KW - land use KW - metacommunity KW - transcriptomics Y1 - 2022 U6 - https://doi.org/10.1111/mec.16348 SN - 0962-1083 SN - 1365-294X VL - 31 IS - 6 SP - 1716 EP - 1734 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Bickel, Samantha L. A1 - Tang, Kam W. A1 - Grossart, Hans-Peter T1 - Structure and function of zooplankton-associated bacterial communities in a temperate estuary change more with time than with zooplankton species JF - Aquatic microbial ecology : international journal N2 - Zooplankton support distinct bacterial communities in high concentrations relative to the surrounding water, but little is known about how the compositions and functionalities of these bacterial communities change through time in relation to environmental conditions. We conducted a year-long field study of bacterial communities associated with common zooplankton groups as well as free-living bacterial communities in the York River, a tributary of Chesapeake Bay. Bacterial community genetic fingerprints and their carbon substrate usage were examined by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA and by Biolog EcoPlates, respectively. Zooplankton-associated communities were genetically distinct from free-living bacterial communities but utilized a similar array of carbon substrates. On average, bacteria associated with different zooplankton groups were genetically more similar to each other within each month (65.4% similarity) than to bacterial communities of the same zooplankton group from different months (28 to 30% similarity), which suggests the importance of ambient environmental conditions in shaping resident zooplankton-associated bacterial communities. Monthly changes in carbon substrate utilization were less variable for zooplankton-associated bacteria than for free-living bacteria, suggesting that the zooplankton microhabitat is more stable than the surrounding water and supports specific bacterial groups in the otherwise unfavorable conditions in the water column. KW - Zooplankton KW - Bacterial communities KW - Carbon substrates KW - Biolog EcoPlates KW - York River Y1 - 2014 U6 - https://doi.org/10.3354/ame01676 SN - 0948-3055 SN - 1616-1564 VL - 72 IS - 1 SP - 1 EP - 15 PB - Institute of Mathematical Statistics CY - Oldendorf Luhe ER - TY - JOUR A1 - Bickel, Samantha L. A1 - Tang, Kam W. A1 - Grossart, Hans-Peter T1 - Ciliate epibionts associated with crustacean zooplankton in German lakes - distribution, motility, and bacterivory JF - Frontiers in microbiology N2 - Ciliate epibionts associated with crustacean zooplankton are widespread in aquatic systems, but their ecological roles are little known. We studied the occurrence of ciliate epibionts on crustacean zooplankton in nine German lakes with different limnological features during the summer of 2011. We also measured the detachment and re-attachment rates of the ciliates, changes in their motility, and the feeding rates of attached vs. detached ciliate epibionts. Epibionts were found in all lakes sampled except an acidic lake with large humic inputs. Epibiont prevalence was as high as 80.96% on the cladoceran Daphnia cucullata, 67.17% on the cladoceran Diaphanosoma brachyurum, and 46.67% on the calanoid copepod Eudiaptomus gracilis. Both cladoceran groups typically had less than 10 epibionts per individual, while the epibiont load on E. gracilis ranged from 1 to >30 epibionts per individual. After the death of the zooplankton host, the peritrich ciliate epibiont Epistylis sp. detached in an exponential fashion with a half-life of 5 min, and 98% detached within 30 min, leaving behind the stalks used for attachment. Immediately after detachment, the ciliates were immotile, but 62% became motile within 60 min. When a new host was present, only 27% reattached after 120 min. The average measured ingestion rate and clearance rate of Epistylis were 11,745 bacteria ciliate(-1) h(-1) and 24.33 mu l ciliate(-1) h(-1), respectively. Despite their high feeding rates, relatively low epibiont abundances were observed in the field, which suggests either diversion of energy to stalk formation, high metabolic loss by the epibionts, or high mortality among the epibiont populations. KW - ciliate epibionts KW - Epistylis KW - crustacean zooplankton KW - bacterivory KW - epibiont motility Y1 - 2012 U6 - https://doi.org/10.3389/fmicb.2012.00243 SN - 1664-302X VL - 3 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Bertilsson, Stefan A1 - Burgin, Amy A1 - Carey, Cayelan C. A1 - Fey, Samuel B. A1 - Grossart, Hans-Peter A1 - Grubisic, Lorena M. A1 - Jones, Ian D. A1 - Kirillin, Georgiy A1 - Lennon, Jay T. A1 - Shade, Ashley A1 - Smyth, Robyn L. T1 - The under-ice microbiome of seasonally frozen lakes JF - Limnology and oceanography N2 - Compared to the well-studied open water of the "growing" season, under-ice conditions in lakes are characterized by low and rather constant temperature, slow water movements, limited light availability, and reduced exchange with the surrounding landscape. These conditions interact with ice-cover duration to shape microbial processes in temperate lakes and ultimately influence the phenology of community and ecosystem processes. We review the current knowledge on microorganisms in seasonally frozen lakes. Specifically, we highlight how under-ice conditions alter lake physics and the ways that this can affect the distribution and metabolism of auto-and heterotrophic microorganisms. We identify functional traits that we hypothesize are important for understanding under-ice dynamics and discuss how these traits influence species interactions. As ice coverage duration has already been seen to reduce as air temperatures have warmed, the dynamics of the under-ice microbiome are important for understanding and predicting the dynamics and functioning of seasonally frozen lakes in the near future. Y1 - 2013 U6 - https://doi.org/10.4319/lo.2013.58.6.1998 SN - 0024-3590 SN - 1939-5590 VL - 58 IS - 6 SP - 1998 EP - 2012 PB - Wiley CY - Waco ER - TY - JOUR A1 - Batista, A. M. M. A1 - Woodhouse, Jason Nicholas A1 - Grossart, Hans-Peter A1 - Giani, A. T1 - Methanogenic archaea associated to Microcystis sp. in field samples and in culture JF - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica N2 - Cyanobacterial mass developments impact the community composition of heterotrophic microorganisms with far-reaching consequences for biogeochemical and energy cycles of freshwater ecosystems including reservoirs. Here we sought to evaluate the temporal stability of methanogenic archaea in the water column and further scrutinize their associations with cyanobacteria. Monthly samples were collected from October 2009 to December 2010 in hypereutrophic Pampulha reservoir with permanently blooming cyanobacteria, and from January to December 2011 in oligotrophic Volta Grande reservoir with only sporadic cyanobacteria incidence. The presence of archaea in cyanobacterial cultures was investigated by screening numerous strains of Microcystis spp. from these reservoirs as well as from lakes in Europe, Asia, and North-America. We consistently determined the occurrence of archaea, in particular methanogenic archaea, in both reservoirs throughout the year. However, archaea were only associated with two strains (Microcystis sp. UFMG 165 and UFMG 175) recently isolated from these reservoirs. These findings do not implicate archaea in the occurrence of methane in the epilimnion of inland waters, but rather serve to highlight the potential of microhabitats associated with particles, including phytoplankton, to shelter unique microbial communities. KW - Cyanobacteria KW - Methanogenic archaea KW - Bacterial community composition KW - Microcystis sp KW - Tropical reservoir Y1 - 2018 U6 - https://doi.org/10.1007/s10750-018-3655-3 SN - 0018-8158 SN - 1573-5117 VL - 831 IS - 1 SP - 163 EP - 172 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Balint, Miklos A1 - Marton, Orsolya A1 - Schatz, Marlene A1 - Düring, Rolf-Alexander A1 - Grossart, Hans-Peter T1 - Proper experimental design requires randomization/balancing of molecular ecology experiments JF - Ecology and evolution N2 - Properly designed (randomized and/or balanced) experiments are standard in ecological research. Molecular methods are increasingly used in ecology, but studies generally do not report the detailed design of sample processing in the laboratory. This may strongly influence the interpretability of results if the laboratory procedures do not account for the confounding effects of unexpected laboratory events. We demonstrate this with a simple experiment where unexpected differences in laboratory processing of samples would have biased results if randomization in DNA extraction and PCR steps do not provide safeguards. We emphasize the need for proper experimental design and reporting of the laboratory phase of molecular ecology research to ensure the reliability and interpretability of results. KW - batch effect KW - bias KW - DNA extraction KW - environmental DNA KW - laboratory practice KW - lake community KW - metabarcoding KW - nondemonic intrusions KW - PCR KW - sediment Y1 - 2018 U6 - https://doi.org/10.1002/ece3.3687 SN - 2045-7758 VL - 8 IS - 3 SP - 1786 EP - 1793 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Bachmann, Jennifer A1 - Heimbach, Tabea A1 - Hassenrück, Christiane A1 - Kopprio, German A. A1 - Iversen, Morten Hvitfeldt A1 - Grossart, Hans-Peter A1 - Gärdes, Astrid T1 - Environmental Drivers of Free-Living vs. Particle-Attached Bacterial Community Composition in the Mauritania Upwelling System JF - Frontiers in microbiology N2 - Saharan dust input and seasonal upwelling along North-West Africa provide a model system for studying microbial processes related to the export and recycling of nutrients. This study offers the first molecular characterization of prokaryotic particle-attached (PA; > 3.0 mu m) and free-living (FL; 0.2-3.0 mu m) players in this important ecosystem during August 2016. Environmental drivers for alpha-diversity, bacterial community composition, and differences between FL and PA fractions were identified. The ultra-oligotrophic waters off Senegal were dominated by Cyanobacteria while higher relative abundances of Alphaproteobacteria, Bacteroidetes, Verrucomicrobia, and Planctomycetes (known particle-degraders) occurred in the upwelling area. Temperature, proxy for different water masses, was the best predictor for changes in FL communities. PA community variation was best explained by temperature and ammonium. Bray Curtis dissimilarities between FL and PA were generally very high and correlated with temperature and salinity in surface waters. Greatest similarities between FL and PA occurred at the deep chlorophyll maximum, where bacterial substrate availability was likely highest. This indicates that environmental drivers do not only influence changes among FL and PA communities but also differences between them. This could provide an explanation for contradicting results obtained by different studies regarding the dissimilarity/similarity between FL and PA communities and their biogeochemical functions. KW - prokaryotes KW - biodiversity KW - microbial ecology KW - alpha diversity KW - Bray Curtis dissimilarity KW - temperature KW - salinity KW - 16S rRNA Illumina amplicon sequencing Y1 - 2018 U6 - https://doi.org/10.3389/fmicb.2018.02836 SN - 1664-302X VL - 9 PB - Frontiers Research Foundation CY - Lausanne 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 - TY - JOUR A1 - Attermeyer, Katrin A1 - Premke, Katrin A1 - Hornick, Thomas A1 - Hilt, Sabine A1 - Grossart, Hans-Peter T1 - Ecosystem-level studies of terrestrial carbon reveal contrasting bacterial metabolism in different aquatic habitats JF - Ecology : a publication of the Ecological Society of America N2 - In aquatic systems, terrestrial dissolved organic matter (t-DOM) is known to stimulate bacterial activities in the water column, but simultaneous effects of autumnal leaf input on water column and sediment microbial dynamics in littoral zones of lakes remain largely unknown. The study's objective was to determine the effects of leaf litter on bacterial metabolism in the littoral water and sediment, and subsequently, the consequences for carbon cycling and food web dynamics. Therefore, in late fall, we simultaneously measured water and sediment bacterial metabolism in the littoral zone of a temperate shallow lake after adding terrestrial particulate organic matter (t-POM), namely, maize leaves. To better evaluate bacterial production (BP) and community respiration (CR) in sediments, we incubated sediment cores with maize leaves of different quality (nonleached and leached) under controlled laboratory conditions. Additionally, to quantify the incorporated leaf carbon into microbial biomass, we determined carbon isotopic ratios of fatty acids from sediment and leaf-associated microbes from a laboratory experiment using C-13-enriched beech leaves. The concentrations of dissolved organic carbon (DOC) increased significantly in the lake after the addition of maize leaves, accompanied by a significant increase in water BP. In contrast, sediment BP declined after an initial peak, showing no positive response to t-POM addition. Sediment BP and CR were also not stimulated by t-POM in the laboratory experiment, either in short-term or in long-term incubations, except for a short increase in CR after 18 hours. However, this increase might have reflected the metabolism of leaf-associated microorganisms. We conclude that the leached t-DOM is actively incorporated into microbial biomass in the water column but that the settling leached t-POM (t-POML) does not enter the food web via sediment bacteria. Consequently, t-POML is either buried in the sediment or introduced into the aquatic food web via microorganisms (bacteria and fungi) directly associated with t-POML and via benthic macroinvertebrates by shredding of t-POML. The latter pathway represents a benthic shortcut which efficiently transfers t-POML to higher trophic levels. KW - bacterial production KW - carbon turnover KW - community respiration KW - leaf litter KW - phospholipid-derived fatty acid KW - PLFA KW - Schulzensee KW - Germany KW - sediments KW - shallow lakes KW - stable isotopes KW - terrestrial subsidies Y1 - 2013 U6 - https://doi.org/10.1890/13-0420.1 SN - 0012-9658 SN - 1939-9170 VL - 94 IS - 12 SP - 2754 EP - 2766 PB - Wiley CY - Washington 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 - Attermeyer, Katrin A1 - Grossart, Hans-Peter A1 - Flury, Sabine A1 - Premke, Katrin T1 - Bacterial processes and biogeochemical changes in the water body of kettle holes - mainly driven by autochthonous organic matter? JF - Aquatic sciences : research across boundaries N2 - Kettle holes are small inland waters formed from glacially-created depressions often situated in agricultural landscapes. Due to their high perimeter-to-area ratio facilitating a high aquatic-terrestrial coupling, kettle holes can accumulate high concentrations of organic carbon and nutrients, fueling microbial activities and turnover rates. Thus, they represent hotspots of carbon turnover in the landscape, but their bacterial activities and controlling factors have not been well investigated. Therefore, we aimed to assess the relative importance of various environmental factors on bacterial and biogeochemical processes in the water column of kettle holes and to disentangle their variations. In the water body of ten kettle holes in north-eastern Germany, we measured several physico-chemical and biological parameters such as carbon quantity and quality, as well as bacterial protein production (BP) and community respiration (CR) in spring, early summer and autumn 2014. Particulate organic matter served as an indicator of autochthonous production and represented an important parameter to explain variations in BP and CR. This notion is supported by qualitative absorbance indices of dissolved molecules in water samples and C: N ratios of the sediments, which demonstrate high fractions of autochthonous organic matter (OM) in the studied kettle holes. In contrast, dissolved chemical parameters were less important for bacterial activities although they revealed strong differences throughout the growing season. Pelagic bacterial activities and dynamics might thus be regulated by autochthonous OM in kettle holes implying a control of important biogeochemical processes by internal primary production rather than facilitated exchange with the terrestrial surrounding due to a high perimeter-to-area ratio. KW - Bacterial production KW - Carbon turnover KW - Growth efficiency KW - Ponds KW - Respiration KW - DOC quality KW - LC-OCD Y1 - 2017 U6 - https://doi.org/10.1007/s00027-017-0528-1 SN - 1015-1621 SN - 1420-9055 VL - 79 SP - 675 EP - 687 PB - Springer CY - Basel ER - TY - JOUR A1 - Arias-Andres, Maria A1 - Rojas-Jimenez, Keilor A1 - Grossart, Hans-Peter T1 - Collateral effects of microplastic pollution on aquatic microorganisms BT - An ecological perspective JF - Trends in Analytical Chemistry N2 - Microplastics (MP) provide a unique and extensive surface for microbial colonization in aquatic ecosystems. The formation of microorganism-microplastic complexes, such as biofilms, maximizes the degradation of organic matter and horizontal gene transfer. In this context, MP affect the structure and function of microbial communities, which in turn render the physical and chemical fate of MP. This new paradigm generates challenges for microbiology, ecology, and ecotoxicology. Dispersal of MP is concomitant with that of their associated microorganisms and their mobile genetic elements, including antibiotic resistance genes, islands of pathogenicity, and diverse metabolic pathways. Functional changes in aquatic microbiomes can alter carbon metabolism and food webs, with unknown consequences on higher organisms or human microbiomes and hence health. Here, we examine a variety of effects of MP pollution from the microbial ecology perspective, whose repercussions on aquatic ecosystems begin to be unraveled. (C) 2018 Elsevier B.V. All rights reserved. KW - Microplastics (MP) KW - Biofilms KW - HGT KW - Microbial ecology KW - Carbon cycling KW - Aquatic ecosystems KW - Health risk assessment Y1 - 2018 U6 - https://doi.org/10.1016/j.trac.2018.11.041 SN - 0165-9936 SN - 1879-3142 VL - 112 SP - 234 EP - 240 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Arias-Andres, Maria A1 - Kluemper, Uli A1 - Rojas-Jimenez, Keilor A1 - Grossart, Hans-Peter T1 - Microplastic pollution increases gene exchange in aquatic ecosystems JF - Environmental pollution N2 - Pollution by microplastics in aquatic ecosystems is accumulating at an unprecedented scale, emerging as a new surface for biofilm formation and gene exchange. In this study, we determined the permissiveness of aquatic bacteria towards a model antibiotic resistance plasmid, comparing communities that form biofilms on microplastics vs. those that are free-living. We used an exogenous and red-fluorescent E. coli donor strain to introduce the green-fluorescent broad-host-range plasmid pKJKS which encodes for trimethoprim resistance. We demonstrate an increased frequency of plasmid transfer in bacteria associated with microplastics compared to bacteria that are free-living or in natural aggregates. Moreover, comparison of communities grown on polycarbonate filters showed that increased gene exchange occurs in a broad range of phylogenetically-diverse bacteria. Our results indicate horizontal gene transfer in this habitat could distinctly affect the ecology of aquatic microbial communities on a global scale. The spread of antibiotic resistance through microplastics could also have profound consequences for the evolution of aquatic bacteria and poses a neglected hazard for human health. KW - Microplastics KW - Aquatic ecosystems KW - Biofilm KW - Horizontal gene transfer KW - Antibiotic resistance Y1 - 2018 U6 - https://doi.org/10.1016/j.envpol.2018.02.058 SN - 0269-7491 SN - 1873-6424 VL - 237 SP - 253 EP - 261 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Arias Andrés, María de Jesús A1 - Kettner, Marie Therese A1 - Miki, Takeshi A1 - Grossart, Hans-Peter T1 - Microplastics: New substrates for heterotrophic activity contribute to altering organic matter cycles in aquatic ecosystems JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Heterotrophic microbes with the capability to process considerable amounts of organic matter can colonize microplastic particles (MP) in aquatic ecosystems. Weather colonization of microorganisms on MP will alter ecological niche and functioning of microbial communities remains still unanswered. Therefore, we compared the functional diversity of biofilms on microplastics when incubated in three lakes in northeastern Germany differing in trophy and limnological features. For all lakes, we compared heterotrophic activities of MP biofilms with those of microorganisms in the surrounding water by using Biolog (R) EcoPlates and assessed their oxygen consumption in microcosm assays with and without MP. The present study found that the total biofilm biomass was higher in the oligo-mesotrophic and dystrophic lakes than in the eutrophic lake. In all lakes, functional diversity profiles of MP biofilms consistently differed from those in the surrounding water. However, solely in the oligo-mesotrophic lake MP biofilms had a higher functional richness compared to the ambient water. These results demonstrate that the functionality and hence the ecological role of MP-associated microbial communities are context-dependent, i.e. different environments lead to substantial changes in biomass build up and heterotrophic activities of MP biofilms. We propose that MP surfaces act as new niches for aquatic microorganisms and that the constantly increasing MP pollution has the potential to globally impact carbon dynamics of pelagic environments by altering heterotrophic activities. (C) 2018 Elsevier B.V. All rights reserved. KW - Microplastics KW - Microorganisms KW - Biofilms KW - Total biomass KW - Heterotrophic activity KW - Functional diversity KW - Multi-functionality index Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2018.04.199 SN - 0048-9697 SN - 1879-1026 VL - 635 SP - 1152 EP - 1159 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Amalfitano, Stefano A1 - Corno, Gianluca A1 - Eckert, Ester A1 - Fazi, Stefano A1 - Ninio, Shira A1 - Callieri, Cristiana A1 - Grossart, Hans-Peter A1 - Eckert, Werner T1 - Tracing particulate matter and associated microorganisms in freshwaters JF - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica N2 - Sediment resuspension represents a key process in all natural aquatic systems, owing to its role in nutrient cycling and transport of potential contaminants. Although suspended solids are generally accepted as an important quality parameter, current monitoring programs cover quantitative aspects only. Established methodologies do not provide information on origin, fate, and risks associated with uncontrolled inputs of solids in waters. Here we discuss the analytical approaches to assess the occurrence and ecological relevance of resuspended particulate matter in freshwaters, with a focus on the dynamics of associated contaminants and microorganisms. Triggered by the identification of specific physical-chemical traits and community structure of particle-associated microorganisms, recent findings suggest that a quantitative determination of microorganisms can be reasonably used to trace the origin of particulate matter by means of nucleic acid-based assays in different aquatic systems. KW - Total suspended solids KW - Resuspended particulate KW - Turbidity KW - Sediment traps KW - Particle-associated microorganisms KW - Pathogens Y1 - 2017 U6 - https://doi.org/10.1007/s10750-017-3260-x SN - 0018-8158 SN - 1573-5117 VL - 800 SP - 145 EP - 154 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Aichner, Bernhard A1 - Dubbert, David A1 - Kiel, Christine A1 - Kohnert, Katrin A1 - Ogashawara, Igor A1 - Jechow, Andreas A1 - Harpenslager, Sarah-Faye A1 - Hölker, Franz A1 - Nejstgaard, Jens Christian A1 - Grossart, Hans-Peter A1 - Singer, Gabriel A1 - Wollrab, Sabine A1 - Berger, Stella Angela T1 - Spatial and seasonal patterns of water isotopes in northeastern German lakes JF - Earth system science data : ESSD N2 - Water stable isotopes (delta O-18 and delta H-2) were analyzed in samples collected in lakes, associated with riverine systems in northeastern Germany, throughout 2020. The dataset (Aichner et al., 2021; https://doi.org/10.1594/PANGAEA.935633) is derived from water samples collected at (a) lake shores (sampled in March and July 2020), (b) buoys which were temporarily installed in deep parts of the lake (sampled monthly from March to October 2020), (c) multiple spatially distributed spots in four selected lakes (in September 2020), and (d) the outflow of Muggelsee (sampled biweekly from March 2020 to January 2021). At shores, water was sampled with a pipette from 40-60 cm below the water surface and directly transferred into a measurement vial, while at buoys a Limnos water sampler was used to obtain samples from 1 m below the surface. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer, with a measurement uncertainty of < 0.15 parts per thousand (delta O-18) and < 0.0 parts per thousand (delta H-2). The data give information about the vegetation period and the full seasonal isotope amplitude in the sampled lakes and about spatial isotope variability in different branches of the associated riverine systems. Y1 - 2022 U6 - https://doi.org/10.5194/essd-14-1857-2022 SN - 1866-3508 SN - 1866-3516 VL - 14 IS - 4 SP - 1857 EP - 1867 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Adel, Mustafa A1 - Elbehery, Ali H. A. A1 - Aziz, Sherry K. A1 - Aziz, Ramy K. A1 - Grossart, Hans-Peter A1 - Siam, Rania T1 - Viruses-to-mobile genetic elements skew in the deep Atlantis II brine pool sediments JF - Scientific reports N2 - The central rift of the Red Sea has 25 brine pools with different physical and geochemical characteristics. Atlantis II (ATIID), Discovery Deeps (DD) and Chain Deep (CD) are characterized by high salinity, temperature and metal content. Several studies reported microbial communities in these brine pools, but few studies addressed the brine pool sediments. Therefore, sediment cores were collected from ATIID, DD, CD brine pools and an adjacent brine-influenced site. Sixteen different lithologic sediment sections were subjected to shotgun DNA pyrosequencing to generate 1.47 billion base pairs (1.47 x 10(9) bp). We generated sediment-specific reads and attempted to annotate all reads. We report the phylogenetic and biochemical uniqueness of the deepest ATIID sulfur-rich brine pool sediments. In contrary to all other sediment sections, bacteria dominate the deepest ATIID sulfur-rich brine pool sediments. This decrease in virus-to-bacteria ratio in selected sections and depth coincided with an overrepresentation of mobile genetic elements. Skewing in the composition of viruses-to-mobile genetic elements may uniquely contribute to the distinct microbial consortium in sediments in proximity to hydrothermally active vents of the Red Sea and possibly in their surroundings, through differential horizontal gene transfer. Y1 - 2016 U6 - https://doi.org/10.1038/srep32704 SN - 2045-2322 VL - 6 SP - 8882 EP - 8888 PB - Nature Publ. Group CY - London ER -