Klaus Jürgens

Klaus Jürgens
Leibniz Institute for Baltic Sea Research | IOW · Department of Biological Oceanography

About

278
Publications
40,449
Reads
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11,085
Citations
Citations since 2017
56 Research Items
4971 Citations
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20172018201920202021202220230200400600800
20172018201920202021202220230200400600800

Publications

Publications (278)
Technical Report
Full-text available
The Benguela Upwelling system off the coast of Namibia shows a distinct variability of upwelling intensity, oxygen supply and primary production. Studies on the coupling of these temporal and spatial variations with microbially driven processes in the water column and in the sediment are only rudimentary. During the BUSUC II cruise the relationship...
Article
Full-text available
The reduction of manganese oxide with sulfide in aquatic redox-stratified systems was previously considered to be mainly chemical, but recent isolation of the Black Sea isolate Candidatus Sulfurimonas marisnigri strain SoZ1 suggests an important role for biological catalyzation. Here we provide evidence from laboratory experiments, field data, and...
Article
Full-text available
Abundance-occupancy relationships (AORs) are an important determinant of biotic community dynamics and habitat suitability. However, little is known about their role in complex bacterial communities, either within a phylogenetic framework or as a function of niche breadth. Based on data obtained in a field study in the St. Lawrence Estuary, we used...
Preprint
Full-text available
Abundance-occupancy relationships (AORs) are an important determinant of biotic community dynamics and habitat suitability. However, little is known about their role in complex bacterial communities, either within a phylogenetic framework or as a function of niche breadth. Based on data obtained in a field study in the St. Lawrence Estuary, we used...
Article
Full-text available
Viruses can significantly influence cyanobacteria population dynamics and activity, and through this the biogeochemical cycling of major nutrients. However, surprisingly little attention has been given to understand how viral infections alter the ability of diazotrophic cyanobacteria for atmospheric nitrogen fixation and its release to the environm...
Article
Full-text available
The genome encodes the metabolic and functional capabilities of an organism and should be a major determinant of its ecological niche. Yet, it is unknown if the niche can be predicted directly from the genome. Here, we conduct metagenomic binning on 123 water samples spanning major environmental gradients of the Baltic Sea. The resulting 1961 metag...
Technical Report
Full-text available
Freshwaters including adjacent floodplains, as well as coastal waters are among the global hotspots of biological diversity. They are also among the most threatened ecosystems on Earth, and yet receive much less attention than terrestrial and marine ecosystems. Not only does the dramatic decline in freshwater biodiversity affect all levels of biolo...
Article
Full-text available
In the Baltic Sea redoxcline, lysogenic viruses infecting prokaryotes have rarely been detected using the commonly used inducing agent mitomycin C. However, it is well known that not all viruses are induceable by mitomycin C and growing evidence suggests that changes in trophic conditions may trigger the induction of lysogenic viruses. We hypothesi...
Article
In microbial ecology, enclosure studies are often used to investigate the effect of single environmental factors on complex bacterial communities. However, in addition to the manipulation, unintended effects (“bottle effect”) may occur due to the enclosure itself. In this study, we analyzed the bacterial communities that originated from three diffe...
Article
Full-text available
Bubbles rising through the water column are known to scavenge organic material and microorganisms, and transport them through the air–sea interface after bursting. This mechanism has important implications for air–sea exchange processes. However, little is known about how bubbles influence the chemical and biological properties of the sea‐surface m...
Article
Full-text available
Salinity is a significant factor for structuring microbial communities, but little is known for aquatic fungi, particularly in the pelagic zone of brackish ecosystems. In this study, we explored the diversity and composition of fungal communities following a progressive salinity decline (from 34 to 3 PSU) along three transects of ca. 2000 km in the...
Article
Full-text available
The Scientific Committee on Oceanographic Research (SCOR) Working Group 144 Microbial Community Responses to Ocean Deoxygenation workshop held in Vancouver, B.C on July 2014 had the primary objective of initiating a process to standardize operating procedures for compatible process rate and multi-omic (DNA, RNA, protein, and metabolite) data collec...
Article
The Black Sea is the world’s largest anoxic basin and a model system for studying processes across redox gradients. In between the oxic surface and the deeper sulfidic waters there is an unusually broad layer of 10–40 m, where neither oxygen nor sulfide are detectable. In this suboxic zone, dissolved phosphate profiles display a pronounced minimum...
Article
Lateral intrusions of oxygen caused by small‐scale mixing are thought to shape microbial activity in marine redoxclines. To examine the response of prokaryotes to such mixing events we employed a shipboard mixing experiment in the euxinic central Baltic Sea: oxic, nitrate containing and sulfidic water samples without detectable oxygenized substance...
Article
Full-text available
Major Baltic inflow (MBI) events carry highly saline water from the North Sea to the central Baltic Sea and thereby affect both its environmental conditions and its biota. While bacterioplankton communities in the Baltic Sea are strongly structured by salinity, how MBIs impact the composition and distribution of bacteria is unknown. The exceptional...
Article
Full-text available
Dispersal can influence the response of bacterial communities to environmental changes and disturbances. However, the extent to which dispersal contributes to the community response in dependence of the character and strength of the disturbance remains unclear. Here, we conducted a transplant experiment using dialysis bags in which bacterioplankton...
Article
Full-text available
The Baltic Sea is one of the world’s largest brackish water bodies and is characterised by pronounced physicochemical gradients where microbes are the main biogeochemical catalysts. Meta-omic methods provide rich information on the composition of, and activities within, microbial ecosystems, but are computationally heavy to perform. We here present...
Article
Full-text available
Predicted increases in sea surface temperatures are expected to shift the balance between autotrophic production and the heterotrophic degradation of organic matter toward a more heterotrophic system. For early phytoplankton spring blooms at low water temperature the impact of rising temperatures has been mainly investigated in mesocosm experiments...
Chapter
Full-text available
Biogeochemistry and Microbiology of Oxygen-Depleted Water Columns
Article
High-throughput sequencing (HTS) techniques have been increasingly used in biodiversity estimates and in the detection of rare species within prokaryotic and eukaryotic assemblages in different habitats. In studies of protists, the V4 region of the 18S rRNA gene is the genetic marker most often used. However, established primers for the variable re...
Article
Full-text available
Salinity has a strong impact on bacterial community composition such that freshwater bacterial communities are very different from those in seawater. By contrast, little is known about the composition and diversity of the bacterial community in the sediments (bacteriobenthos) at the freshwater-seawater transition (mesohaline conditions). In this st...
Article
The assessment of functional redundancy (FR) is essential to understand community structure-function relationships because FR buffers the functional performance of communities against changes in community composition. We introduce a novel metatranscriptome-based approach to quantify FR, which permits multifunctional aspects to be addressed. FR amon...
Article
Full-text available
Global warming affects the thermal stratification of freshwater lakes, and thus can lead to thermocline deepening. To follow the direct and indirect effects of thermocline shifts on processes at the sediment–water interface, the thermoclines in six of twelve lake enclosures were deepened by pumping warm surface water below the thermocline. Hypolimn...
Article
Full-text available
Bacterivory among small (≤ 20 μm) phytoflagellates (SP) is increasingly recognized as a globally relevant phenomenon, impacting a wide range of aspects from primary production levels to marine fisheries. However, to correctly parametrize mixotrophic SP in biogeochemical and food web models, a better understanding of the magnitude and regulation of...
Article
Full-text available
Throughout the Baltic Sea redoxcline, virus production and the frequency of lytically-infected prokaryotic cells were estimated from parallel incubations of undiluted seawater and seawater that contained prokaryotes with substantially reduced numbers of viruses (virus dilution approach), effectively preventing viral reinfection during the incubatio...
Data
Equations to calculate prokaryotic growth (PG), prokaryotic mortality, PG corrected for prokaryotic mortality, virus production (VP), viral decay (VD), VP corrected for VD, and FIC. Parameters were calculated from temporal changes in prokaryotic and viral abundance during the incubations where Pmaxn and Pminn correspond to the nth local maximum and...
Data
Variation partitioning of FIC and VP based on virus-to-prokaryote ratio and turbidity. The table gives the fraction (%) of the variation of the frequency of infected cells (FIC) and virus production (VP) explained by the specific model and its corresponding p-value (n.a.: not applicable). The virus-to-prokaryote ratio served as explanatory and turb...
Data
Prokaryotic and viral abundances for undiluted and virus dilution experiments. Abundances were determined every 5 h after start of the incubations (t0). (XLS)
Data
Variation partitioning of FIC and VP based on nutrient concentrations and water masses. The table gives the fraction (%) of the variation of the frequency of infected cells (FIC) and virus production (VP) explained by the specific model and its corresponding p-value (n.a.: not applicable). The concentrations of NO2, NH4, and PO4 served as explanato...
Data
Rates of prokaryotic growth (PG), prokaryotic mortality, PG corrected for prokaryotic mortality, viral decay (VD), and virus production corrected for VD (VP corrected for VD). The table gives average (Avg) and range of prokaryotic growth (PG; N×103 mL-1 h-1), prokaryotic mortality (N×103 mL-1 h-1), prokaryotic growth corrected for prokaryotic morta...
Data
Compilation of prokaryotic and viral abundance, virus-to-prokaryote ratio, virus production, viral turnover time, viral turnover, and burst size. The tables give prokaryotic abundance (PA, N×105 mL-1), viral abundance (VA, N×106 mL-1), the virus-to-prokaryote ratio (VPR), virus production (VP, N×104 mL-1 h-1), viral turnover time (VTT, d), viral tu...
Data
Changes in prokaryotic and viral abundance during an incubation experiment, conducted with seawater from the anoxic zone at Gotland Deep using the virus dilution approach. The Figure shows local minima and maxima of prokaryotic (Pminn and Pmaxn) and viral abundance (Vminn and Vmaxn) and their respective time points (TPminn, TPmaxn, TVminn, and TVma...
Data
Relative abundances of Bacteria (A,C,E) and Crenarchaeota (B,D,F) in in situ samples (dark grey bars) and at termination of experimental incubations performed at Gotland Deep (A,B), Landsort Deep 1 (C,D), and Landsort Deep 2 (E,F). Undiluted (white bars) and virus dilution incubations (grey bars) were performed with water from the oxic (OZ), suboxi...
Data
Kruskal-Wallis test for differences in the relative abundance of bacteria and crenarchaeota. The table gives the test statistic (H) and the corresponding p-value of a Kruskal-Wallis test performed with the relative abundance of Bacteria and Crenarchaeota of in situ samples and data from undiluted and virus dilution incubations at the end of the inc...
Chapter
1. Environmental drivers and food web structure in the pelagic zone vary from south to north in the Baltic Sea. 2. While nitrogen is generally the limiting nutrient for primary production in the Baltic Sea, phosphorus is the limiting nutrient in the Bothnian Bay. 3. In the Gulf of Bothnia the food web is to a large extent driven by terrestrial allo...
Article
In response to global warming, increasing quantities of tDOM are transported through estuaries from land to the sea. In this study we investigated microbial responses to increased tDOM concentrations in three salinity regimes (salinity: 32, 7 and 3) characteristic of the Baltic Sea. Mesocosm experiments performed in May and November revealed low (0...
Article
Full-text available
The processing of terrestrial dissolved organic matter (DOM) in coastal shelf seas is an important part of the global carbon cycle, yet, it is still not well understood. One of the largest brackish shelf seas, the Baltic Sea in northern Europe, is characterized by high freshwater input from sub-arctic rivers and limited water exchange with the Atla...
Article
Chemolithoautotrophic sulfur-oxidizing and denitrifying Gamma- (particularly the SUP05 cluster) and Epsilonproteobacteria (predominantly Sulfurimonas subgroup GD17) are assumed to compete for substrates (electron donors and acceptors) in marine pelagic redox gradients. In order to elucidate their ecological niche separation we performed 34S0, 15NO3...
Article
Full-text available
The study of cultured strains has a long tradition in protistological research and has greatly contributed to establishing the morphology, taxonomy and ecology of many protist species. However, cultivation-independent techniques, based on 18S rRNA gene sequences, have demonstrated that natural protistan assemblages mainly consist of hitherto uncult...
Article
Full-text available
Early spring phytoplankton blooms can occur at very low water temperatures but they are often decoupled from bacterial growth, which is assumed to be often temperature controlled. In a previous mesocosm study with Baltic Sea plankton communities, an early diatom bloom was associated with a high relative abundance of Glaciecola sequences (Gammaprote...
Article
Full-text available
Understanding the key processes that control bacterial community composition has enabled predictions of bacterial distribution and function within ecosystems. In this study, we used the Baltic Sea as a model system to quantify the phylogenetic signal of salinity and season with respect to bacterioplankton community composition. The abundances of 16...
Article
Full-text available
In contrast to clear stimulatory effects of rising temperature, recent studies of the effects of CO2 on planktonic bacteria have reported conflicting results. To better understand the potential impact of predicted climate scenarios on the development and performance of bacterial communities, we performed bifactorial mesocosm experiments (pCO2 and t...
Article
One of the most prominent manifestations of the ongoing climate warming is the retreat of glaciers and ice sheets around the world. Retreating glaciers result in the formation of new ponds and lakes, which are available for colonization. The gradual appearance of these new habitat patches allows us to determine to what extent the composition of ase...
Article
Full-text available
The gut microbiota has many beneficial effects on host metabolism and health, and its composition is determined by numerous factors. It is also assumed that there was a co-evolution of mammals and the bacteria inhabiting their gut. Current knowledge of the mammalian gut microbiota mainly derives from studies on humans and terrestrial animals, where...
Article
Full-text available
Many studies on bacterial community composition (BCC) do not distinguish between particle-associated (PA) and free-living (FL) bacteria or neglect the PA fraction by pre-filtration removing most particles. Although temporal and spatial gradients in environmental variables are known to shape BCC, it remains unclear how and to what extent PA and FL b...
Data
Unweighted-pair group method with arithmetic mean (UPGMA) dendograms based on Bray-Curtis dissimilarities of PA and FL bacteria distribution at different stations [marine (A), mesohaline (B), oligohaline (C), and for all samples (D)].
Data
Unweighted-pair group method with arithmetic mean (UPGMA) dendograms based on Bray-Curtis dissimilarities of the distribution of PA and FL bacteria at different stations in summer and winter marine (A,D), mesohaline (B,E), oligohaline (C,F).
Data
Rarefaction curves for free-living and particle-associated samples of the total dataset.
Data
Number of OTUs, reads, Chao1, Shannon [H], and Simpson [1-D] and Buzas and Gibson's Evenness [e∧H/S] diversity indexes of averages of samples after normalization to 430 reads per sample. PA, particle-attached; FL, free-living; PA, particle-associated fraction; FL, free-living fraction; Tot, total bacteria.
Data
Wilcoxon Rank sum test between all samples within station and season and a factor (F) from 0 to 1, which compares the groups [triplicates (a, b, c) vs. fractions (PA, FL)] within one station (mar, meso, oligo) and season (summer, fall/winter) to estimate the difference between the fractions, with 1 as highest possible difference.
Poster
Full-text available
Recent studies reported conflicting results of CO2 effects on planktonic bacteria. To obtain a better understanding of the impact of future climate scenarios on the development of bacterial communities, we performed bifactorial mesocosm experiments (pCO2 and temperature) with Baltic Sea water, during a diatom bloom in autumn and during a cyanobacte...
Article
For many years, the genus Massisteria (Cercozoa, Leucodictyida) comprised only one species, M. marina. This small species has a biphasic life cycle and feeds through filose, radiating pseudopodia. It has a distinct swimming form and is regularly detected in association with detritus aggregates. However, environmental sequences closely related to th...
Article
Full-text available
The aim of the present study was to evaluate the influence of different light quality, especially ultraviolet radiation (UVR), on the dynamics of volatile halogenated organic compounds (VHOCs) at the sea surface. Short term experiments were conducted with floating gas-tight mesocosms of different optical qualities. Six halocarbons (CH3I, CHCl3, CH2...
Article
Full-text available
Upwelling areas are shaped by enhanced primary production in surface waters, accompanied by a well-investigated planktonic succession. Although bacteria play an important role in biogeochemical cycles of upwelling systems, little is known about bacterial community composition and its development during upwelling events. The aim of this study was to...
Article
Full-text available
Ammonia-oxidizing archaea (AOA) are an important component of the planktonic community in aquatic habitats, linking nitrogen and carbon cycles through nitrification and carbon fixation. Therefore, measurements of these processes in culture-based experiments can provide insights into their contributions to energy conservation and biomass production...
Data
Epsilonproteobacteria have been found globally distributed in marine anoxic/sulfidic areas mediating relevant transformations within the sulfur and nitrogen cycles. In the Baltic Sea redox zones, chemoautotrophic epsilonproteobacteria mainly belong to the Sulfurimonas gotlandica GD17 cluster for which recently a representative strain, S. gotlandica...