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Crustaceans increasingly suffer from the black spot shell disease syndrome, which principally results from bacterial breakdown of their chitinous exoskeleton. Since Cancer pagurus is highly susceptible to this disease, we compared the bacterial communities of black spot affected and non-affected areas of the carapace by amplicon sequencing of 16S rRNA genes and 16S rRNA. Within each spot, bacterial communities of affected areas were less diverse compared to communities from non-affected areas. Communities of different affected spots were, however, more divergent from each other, compared to those of different nonaffected areas. This indicates a reduced and shifted microbial community composition caused by the black spot disease. Different communities found in black spots likely indicate different stages of the disease. In affected areas, Flavobacteriaceae rose up to one of the most abundant and active families, due to massive increase of Aquimarina spp., suggesting a significant role in shell disease syndrome. We isolated 75 bacterial strains from diseased and healthy areas, which primarily affiliated with Proteobacteria and Bacteroidetes, thus reflecting the dominant phyla detected by amplicon sequencing. The ability to degrade chitin was mainly found for Gammaproteobacteria and Aquimarina spp. within the Flavobacteriia, while the ability to use N-acetylglucosamine, the monomer of the polysaccharide chitin, was observed for most isolates, including many Alphaproteobacteria. Furthermore, one third of the isolates showed antagonistic properties. The combination of bacterial community analysis and the physiological properties of the isolates provides insights into a functional complex epibacterial community on the carapace of C. pagurus. Importance In recent years, the shell disease syndrome was detected for several ecologically and economically important crustacean species. Large proportions of populations are affected, e.g., >60% of the widely distributed species Cancer pagurus in different North Sea areas. Bacteria play a significant role in the development of different forms of shell disease, all characterized by microbial chitinolytic degradation of the outer shell. By comparing the bacterial communities of healthy and diseased areas of the shell of C. pagurus we could demonstrate that the disease causes a reduced bacterial diversity within affected areas, a phenomenon co-occurring also with many other diseases. Furthermore, the community composition dramatically changed, with some taxa rising to high relative abundances and showing increased activity, indicating a strong participation in shell disease. Characterization of bacterial isolates obtained from affected and non-affected spots provided deeper insights in their physiological properties and thus the possible role within the microbiome.

It is generally recognized that phages are a mortality factor for their bacterial hosts. This could be particularly true in spring phytoplankton blooms, which are known to be closely followed by a highly specialized bacterial community. We hypothesized that phages modulate these dense heterotrophic bacteria successions following phytoplankton blooms. In this study, we focused on Flavobacteriia, because they are main responders during these blooms and have an important role in the degradation of polysaccharides. A cultivation-based approach was used, obtaining 44 lytic flavobacterial phages (flavophages), representing twelve new species from two viral realms. Taxonomic analysis allowed us to delineate ten new phage genera and ten new families, from which nine and four, respectively, had no previously cultivated representatives. Genomic analysis predicted various life styles and genomic replication strategies. A likely eukaryote-associated host habitat was reflected in the gene content of some of the flavophages. Detection in cellular metagenomes and by direct-plating showed that part of these phages were actively replicating in the environment during the 2018 spring bloom. Furthermore, CRISPR/Cas spacers and re-isolation during two consecutive years suggested that, at least part of the new flavophages are stable components of the microbial community in the North Sea. Together, our results indicate that these diverse flavophages have the potential to modulate their respective host populations.

Microplastics (MP), as novel substrata for microbial colonization within aquatic ecosystems, are a matter of growing concern due to their potential to propagate foreign or invasive species across different environments. MP are known to harbour a diversity of microorganisms, yet little is understood of the dynamics of their biofilms and their capacity to successfully displace these microorganisms across different aquatic ecosystems typically marked by steep salinity gradients. To address this, we performed an in situ sequential incubation experiment to simulate MP transport from riverine to coastal seawaters using synthetic (high-density polyethylene, HDPE and tyre wear, TW) and natural (Wood) substrata. Bacterial communities on incubated particles were compared to each other as well as to those in surrounding waters, and their dynamics along the gradient investigated. All communities differed significantly from each other in their overall structure along the salinity gradient and were shaped by different ecological processes. While HDPE communities were governed by environmental selection, those on TW and Wood were dominated by stochastic events of dispersal and drift. Upon transfer into coastal seawaters, an almost complete turnover was observed among HDPE and TW communities. While synthetic particles displaced a minor proportion of communities across the salinity gradient, some of these comprised putatively pathogenic and resistant taxa. Our findings present an extensive assessment of MP biofilms and their dynamics upon displacement across different aquatic systems, presenting new insights into the role of MP as transport vectors. Also see: https://micro2022.sciencesconf.org/426985/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Shelf sea areas are the primary oceanic source for methane release, the most abundant hydrocarbon in the atmosphere. As such, the southern North Sea’s methane concentration is mainly determined by river runoff and tidal marshes. Within such a highly variable temperate estuary, this study is the first to reveal detailed information on the in situ activity, abundance and community structure of methane oxidizing bacteria along a transect from the marine environment near Helgoland island to the riverine harbor of Hamburg, Germany. The in situ methane oxidation rate was determined with a radio tracer, and methane concentration with the head-space method. Abundance and diversity of the methanotrophic bacterial community in the water column was assessed with quantitative polymerase chain reaction for the particulate methane monooxygenase and monooxygenase intergenic spacer analysis. Median abundances ranged from 2.8 × 104 cells l−1 in the marine environment to 7.5 × 105 cells l−1 in the riverine environment. Except for salinity, no conclusive linear correlation between any environmental parameter and the abundance of methanotrophs could be determined. Relating activity with abundance of methanotrophs showed that about 70% of the population is inactive, especially in the coastal and marine environment. This study found distinct operational taxonomic unit (OTU) community compositions among the 3 environmental categories (river, coast, marine). Several identified OTUs have been reported previously and imply a wide geographic occurrence. Overall, we propose that salinity is the most important driver of differing communities in the riverine, coastal and marine environment.

It is generally recognized that phages have a modulating role in the marine environment. Therefore, we hypothesized that phages can be a mortality factor for the dense heterotrophic bacterial population succeeding in phytoplankton blooms. For the marine carbon cycle, spring phytoplankton blooms are important recurring events. In this study, we focused onFlavobacteriia, because they are main responders during these blooms and have an important role in the degradation of polysaccharides. A cultivation-based approach was used, obtaining 44 lytic flavobacterial phages (flavophages), representing twelve new species from two viral realms –DuplodnaviriaandMonodnaviria. Taxonomic analysis allowed us to delineate ten new phage genera and seven new families, from which nine and four, respectively, had no previously cultivated representatives. Genomic analysis predicted various life styles and genomic replication strategies. A likely eukaryote-associated host habitat was reflected in the gene content of some of the flavophages. Detection in cellular metagenomes and by direct-plating indicated that part of these phages were actively replicating in the environment during the 2018 spring bloom. Furthermore, CRISPR/Cas spacers and re-isolation during two consecutive years indicated that, at least part of the new flavophages are stable components of the microbial community in the North Sea. Together, our results indicate that these diverse flavophages have the potential to modulate their respective host populations.

Marine fungi are an important component of pelagic planktonic communities. However, it is not yet clear how individual fungal taxa are integrated in marine processes of the microbial loop and food webs. Most likely, biotic interactions play a major role in shaping the fungal community structure. Thus, the aim of our work was to identify possible biotic interactions of mycoplankton with phytoplankton and zooplankton groups and among fungi, and to investigate whether there is coherence between interactions and the dynamics, abundance and temporal occurrence of individual fungal OTUs. Marine surface water was sampled weekly over the course of 1 year, in the vicinity of the island of Helgoland in the German Bight (North Sea). The mycoplankton community was analyzed using 18S rRNA gene tag-sequencing and the identified dynamics were correlated to environmental data including phytoplankton, zooplankton, and abiotic factors. Finally, co-occurrence patterns of fungal taxa were detected with network analyses based on weighted topological overlaps (wTO). Of all abundant and persistent OTUs, 77% showed no biotic relations suggesting a saprotrophic lifestyle. Of all other fungal OTUs, nearly the half (44%) had at least one significant negative relationship, especially with zooplankton and other fungi, or to a lesser extent with phytoplankton. These findings suggest that mycoplankton OTUs are embedded into marine food web chains via highly complex and manifold relationships such as parasitism, predation, grazing, or allelopathy. Furthermore, about one third of all rare OTUs were part of a dense fungal co-occurrence network probably stabilizing the fungal community against environmental changes and acting as functional guilds or being involved in fungal cross-feeding. Placed in an ecological context, strong antagonistic relationships of the mycoplankton community with other components of the plankton suggest that: (i) there is a top-down control by fungi on zooplankton and phytoplankton; (ii) fungi serve as a food source for zooplankton and thereby transfer nutrients and organic material; (iii) the dynamics of fungi harmful to other plankton groups are controlled by antagonistic fungal taxa. © Copyright © 2020 Banos, Gysi, Richter-Heitmann, Glöckner, Boersma, Wiltshire, Gerdts, Wichels and Reich.

Rivers are an important transport route of anthropogenic litter from inland sources toward the sea. A collaborative (i.e. citizen science) approach was used to evaluate the litter pollution of rivers in Germany: schoolchildren within the project “Plastic Pirates” investigated rivers across the entire country during the years 2016 and 2017 by surveying floating macrolitter at 282 sites and taking 164 meso−/microplastic samples (i.e. particles 24.99–5 mm, and 4.99–1 mm, respectively). Floating macrolitter was sighted at 54% of sampling sites and floating macrolitter quantities ranged from 0 to 8.25 items m−1 h−1 (average of 0.34 ± 0.89 litter items m−1 h−1). Floating meso−/microplastics were present at 57% of the sampling sites, and floating meso−/microplastic quantities ranged from 0 to 220 particles h−1 (average of 6.86 ± 24.11 items h−1). As only particles >1 mm were sampled and analyzed, the pollution of rivers in Germany by microplastics could be a much more prevalent problem, regardless of the size of the river. We identified six plastic pollution hotspots where 60% of all meso−/microplastics collected in the present study were found. These hotspots were located close to a plastic-producing industry site, a wastewater treatment plant, at and below weirs, or in residential areas. The composition of the particles at these hotspots indicates plastic producers and possibly the construction industry and wastewater treatment plants as point sources. An identification of litter hotspots would enable specific mitigation measures, adjusted to the respective source, and thereby could prevent the release of large quantities of small plastic particles in rivers. The adopted large-scale citizen science approach was especially suitable to detect pollution hotspots by sampling a variety of rivers, large and small, and enabled a national overview of litter pollution in German rivers.

The Lena River is one of the largest Russian rivers draining into the Laptev Sea. The predicted increases in global temperatures are expected to cause the permafrost areas surrounding the Lena Delta to melt at increasing rates. This melting will result in high amounts of methane reaching the waters of the Lena and the adjacent Laptev Sea. The only biological sink that can lower methane concentrations within this system is methane oxidation by methanotrophic bacteria. However, the polar estuary of the Lena River, due to its strong fluctuations in salinity and temperature, is a challenging environment for bacteria. We determined the activity and abundance of aerobic methanotrophic bacteria by a tracer method and by the quantitative polymerase chain reaction. We described the methanotrophic population with a molecular fingerprinting method (monooxygenase intergenic spacer analysis), as well as the methane distribution (via a headspace method) and other abiotic parameters, in the Lena Delta in September 2013. The median methane concentrations were 22 nmol L−1 for riverine water (salinity (S) −1 for mixed water (5 S −1 for polar water (S > 20). The Lena River was not the source of methane in surface water, and the methane concentrations of the bottom water were mainly influenced by the methane concentration in surface sediments. However, the bacterial populations of the riverine and polar waters showed similar methane oxidation rates (0.419 and 0.400 nmol L−1 d−1), despite a higher relative abundance of methanotrophs and a higher estimated diversity in the riverine water than in the polar water. The methane turnover times ranged from 167 days in mixed water and 91 days in riverine water to only 36 days in polar water. The environmental parameters influencing the methane oxidation rate and the methanotrophic population also differed between the water masses. We postulate the presence of a riverine methanotrophic population that is limited by sub-optimal temperatures and substrate concentrations and a polar methanotrophic population that is well adapted to the cold and methane-poor polar environment but limited by a lack of nitrogen. The diffusive methane flux into the atmosphere ranged from 4 to 163 µmol m2 d−1 (median 24). The diffusive methane flux accounted for a loss of 8 % of the total methane inventory of the investigated area, whereas the methanotrophic bacteria consumed only 1 % of this methane inventory. Our results underscore the importance of measuring the methane oxidation activities in polar estuaries, and they indicate a population-level differentiation between riverine and polar water methanotrophs.

Increases in atmospheric carbon dioxide (CO2) change ocean chemistry, as dissolved CO2 leads to a reduction in the seawater pH. Many marine taxa have been shown to be affected by ocean acidification, while information on marine fungi is lacking. Here, we analyze the effect of pH on mycoplankton communities. The pH of microcosms was adjusted to a value mimicking the predicted ocean acidification in the near future. Fungal communities were analyzed using a double-marker gene approach, allowing a more detailed analysis of their response using 454 pyrosequencing. Mycoplankton communities in microcosms with in situ and adjusted water pH values differed significantly in terms of structure and diversity. The differences were mainly based on abundance shifts among the dominant taxa rather than the exclusion of fungal groups. A sensitivity to lower pH values was reported for several groups across the fungal kingdom and was not phylogenetically conserved. Some of the fungal species that dominated the communities of microcosms with a lower pH were known pathogenic fungi. With the increasing awareness of the significant role fungi play in marine systems, including performing a diverse range of symbiotic activities, our results highlight the importance of including fungi in further research projects studying and modeling biotic responses to the predicted ocean acidification.

The incidence of potentially pathogenic Vibrio species in the marine environment around Europe, is correlated with the increase of surface seawater temperature. Despite their importance, little is known about the trigger factors of potential outbreak-causing strains in this region. As prophages may compose a major reservoir of virulence traits in marine ecosystems, this study aims to identify and characterize the genomes of lysogenic Vibrio phages exemplarily from the North Sea. Therefore, 31 isolates from potentially pathogenic Vibrio species from the North Sea were screened for inducible prophages with mitomycin C. From them, one V. cholerae isolate and 40% V. parahaemolyticus isolates carried inducible prophages. Three lysogenic phages were selected for genomic characterization. The phage vB_VpaM_VP-3212 (unclassified Myoviridae) has a genome with a length of 36.81 Kbp and 55 CDS were identified. This lysogenic phage of V. parahaemolyticus contains genes related to replicative transposition mechanism, such as transposase and mobile elements similar to Mu-like viruses. The phage vB_VpaP_VP-3220 (Podoviridae, unclassified Nona33virus) has a genome length of 58,14 Kbp and contains 63 CDS. This V. parahaemolyticus phage probably uses a headful (pac) packaging replication mechanism. The phage vB_VchM_VP-3213 (unclassified Myoviridae) has a genome with a length of 41 Kbp and 63 CDS were identified, including integrase and Xer system for lysogenic recombination. This lysogenic phage of V. cholerae has similar genomic features as lambdoid phages. Although no pathogenicity genes were identified, their similarity among other phage genomes indicates that these phages can affect the development of pathogenic Vibrio strains in marine environments.

The seawater temperature rise can promote the growth of potentially pathogenic Vibrio species. In the North Sea, V. parahaemolyticus strains have been isolated and characterized. These strains contain prophages that may contribute to the emergence of pathogenic strains in the marine environment. Here, we present the genome structure and possible biological functions of the inducible phage vB_VpaI_VP-3218, a novel filamentous phage carried by the V. parahaemolyticus strain VN-3218. Prophages of the strain VN-3218 were induced with mitomycin C and the DNA from the phage induction was sequenced. Two incomplete prophages were identified, only one complete phage genome with length of 11,082 bp was characterized. The phage vB_VpaI_VP-3218 belongs to the Inoviridae family and shows close homology to the Saetivirus genus. This phage can integrate into the chromosomal host genome and carries host-related regions absent in similar phage genomes, suggesting that this phage might integrate in other Vibrio host genomes from the environment. Furthermore, this phage might have a role in pathogenicity due to potential zonula occludens toxin genes. Based on its genomic similarity, the genome of vB_VpaI_VP-3218 phage probably integrates into the lysogen's chromosome and replicates as episome. This study complements prophage induction and bioinformatic studies applied to non-model species of potentially pathogenic Vibrio species. The characterization of this phage provides new insights with respect to the presence of filamentous phages in environmental V. parahaemolyticus strains, which might have a role in the emergence of new pathogenic strains in the North Sea.

An increase in human Vibrio spp. infections has been linked to climate change related events, in particular to seawater warming and heatwaves. However, there is a distinct lack of research of pathogenic Vibrio spp. occurrences in the temperate North Sea, one of the fastest warming seas globally. Particularly in the German Bight, Vibrio investigations are still scarce. This study focuses on the spatio-temporal quantification and pathogenic characterization of V. parahaemolyticus, V. vulnificus and V. cholerae over the course of 14 months. Species-specific MPN-PCR (Most probable number – polymerase chain reaction) conducted on selectively enriched surface water samples revealed seasonal patterns of all three species with increased abundances during summer months. The extended period of warm seawater coincided with prolonged Vibrio spp. occurrences in the German Bight. Temperature and nitrite were the factors explaining variations in Vibrio spp. abundances after generalized additive mixed models. The specific detection of pathogenic markers via PCR revealed trh-positive V. parahaemolyticus, pathogenic V. vulnificus (nanA, manIIA, PRXII) and V. cholerae serotype O139 presence. Additionally, spatio-temporally varying virulence profiles of V. cholerae with multiple accessory virulence-associated genes, such as the El Tor variant hemolysin (hlyAET), acyltransferase of the repeats-in-toxin cluster (rtxC), Vibrio 7th pandemic island II (VSP-II), Type III Secretion System (TTSS) and the Cholix Toxin (chxA) were detected. Overall, this study highlights that environmental human pathogenic Vibrio spp. comprise a reservoir of virulence-associated genes in the German Bight, especially in estuarine regions. Due to their known vast genetic plasticity, we point to the possible emergence of highly pathogenic V. cholerae strains. Particularly, the presence of V. cholerae serotype O139 is unusual and needs urgent continuous surveillance. Given the predictions of further warming and more frequent heatwave events, human pathogenic Vibrio spp. should be seriously considered as a developing risk to human health in the German Bight.

Jellyfi sh blooms have increased worldwide, and the outbreaks of jellyfi sh population not only aff ect the food web structures via voracious predation but also play an important role in the dynamics of nutrients and oxygen in planktonic food webs. However, it remains unclear whether specifi c carbon compounds released through jellyfi sh metabolic processes have the potential to shape bacterial community composition. Therefore, in this study, we aimed to investigate the compositional succession of the bacterioplankton community in response to the dissolved organic matter (DOM) released by the live Scyphomedusae Cyanea lamarckii and Chrysaora hysoscella collected from Helgoland Roads of the North Sea. The bacterial community was signifi cantly stimulated by the DOM released form live jellyfish and different dominant phylotypes were observed for these two Scyphomedusae species. Furthermore, the bacterial community structures in the diff erent DOM sources, jellyfi sh-incubated media, Kabeltonne seawater, and artificial seawater (DOM-free) were signifi cantly diff erent, as revealed by automated ribosomal intergenic spacer analysis fingerprints. Catalyzed reporter deposition fl uorescence in situ hybridization (CARD-FISH) revealed a rapid species-specific shift in bacterial community composition. Gammaproteobacteria dominated the community instead of the Bacteroidetes community for C . lamarckii, whereas Gammaproteobacteria and Bacteroidetes dominated the community for C . hysoscella. The signifi cant diff erences in the bacterial community composition and succession indicate that the components of the DOM released by jellyfish might differ with jellyfish species.

The prevalence of multidrug-resistant Gram-negative bacteria in aquatic environments has been a long withstanding health concern, namely extended-spectrum beta-lactamase (ESBL) producing Escherichia coli. Given increasing reports on microplastic (MP) pollution in these environments, it has become crucial to better understand the role of MP particles as transport vectors for such multidrug-resistant bacteria. In this study, an incubation experiment was designed where particles of both synthetic and natural material (HDPE, tyre wear, and wood) were sequentially incubated at multiple sites along a salinity gradient from the Lower Weser estuary (Germany) to the offshore island Helgoland (German Bight, North Sea). Following each incubation period, particle biofilms and water samples were assessed for ESBL-producing E. coli, first by the enrichment and detection of E. coli using Fluorocult® LMX Broth followed by cultivation on CHROMAgar™ ESBL media to select for ESBL-producers. Results showed that general E. coli populations were present on the surfaces of wood particles across all sites but none were found to produce ESBLs. Additionally, neither HDPE nor tyre wear particles were found to harbour any E. coli. Conversely, ESBL-producing E. coli were present in surrounding waters from all sites, 64% of which conferred resistances against up to 3 other antibiotic groups, additional to the beta-lactam resistances intrinsic to ESBL-producers. This study provides a first look into the potential of MP to harbour and transport multidrug-resistant E. coli across different environments and the approach serves as an important precursor to further studies on other potentially harmful MP-colonizing species.

Die letzte Lieferung enthielt 70 Stück. Bestellt waren 7 000. Mit 70 Masken kommen 250 Mitarbeiter noch nicht mal durch eine Schicht. Und die begehrten FFP-Masken für alle an der Front waren gar nicht dabei. Dazu kamen noch 30 Schutzanzüge an, allerdings alle in der Größe XS und daher nur für einen kleinen Teil der Belegschaft nutzbar.

To understand the ecological impacts of the “Plastisphere”, those microbes need to be identified that preferentially colonize and interact with synthetic polymer surfaces, as opposed to general surface colonizers. It was hypothesized that the microbial biofilm composition varies distinctly between different substrates. A long-term incubation experiment was conducted (15month) with nine different synthetic polymer films as substrate as well as glass using a natural seawater flow-through system. To identify colonizing microorganisms, 16S and 18SrRNA gene tag sequencing was performed. The microbial biofilms of these diverse artificial surfaces were visualized via scanning electron microscopy. Biofilm communities attached to synthetic polymers are distinct from glass associated biofilms; apparently a more general marine biofilm core community serves as shared core among all synthetic polymers rather than a specific synthetic polymer community. Nevertheless, characteristic and discriminatory taxa of significantly different biofilm communities were identified, indicating their specificity to a given substrate.

Over the last decades there has been an increasing awareness within the scientific community of the importance of communicating science. A growing number of multiple citizen science programs aimed at facilitating the sharing of scientific knowledge with the public. One such approach adopts narrative role plays, involving interactive games which simulate real life situations in a safe environment. During these simulations, participants adopt different roles (scientist, politician) and are posed with a specific research question relevant to e.g. environmental protection. With the AWI school lab OPENSEA we developed a narrative role play on marine litter. In this narrative role playing provides an opportunity at hands-on research and discovery from four different perspectives of plastic pollution. High School students learn about the different perspectives of plastic pollution in the course of different phases through hands-on research and discovery. We apply recent scientific findings and literature as well as, interactive modules designed to take place both on-field and in the lab. The modules are designed to be also applicable for classroom setting which are implemented to the education for sustainable development.

Propomos uma reflexao sobre como o discurso mediatico contribui para o mito do corpo feminino na sociedade actual. Analisamos como os anuncios publicitarios, reportagens e imagens que compoe o discurso das revistas femininas, propoem uma identidade irreal para a mulher, enaltecem a beleza fisica e sensual, projectam imagens do ideal de vida feminino onde se mitifica o papel da sexualidade. Analisamos o discurso das revistas femininas mais lidas em Portugal durante o ano de 2012, nomeadamente as edicoes da revista Activa e Happy Woman e centramo-nos na reflexao teorica recorrendo a autores de referencia no campo dos estudos de genero e analise mediatico.

The spatial distribution of bacterial populations in marine bioaerosol samples was investigated during a cruise from the North Sea to the Baltic Sea via Skagerrak and Kattegat. The analysis of the sampled bacterial communities with a pyrosequencing approach revealed that the most abundant phyla were represented by the Proteobacteria (49.3%), Bacteroidetes (22.9%), Actinobacteria (16.3%), and Firmicutes (8.3%). Cyanobacteria were assigned to 1.5% of all bacterial reads. A core of 37 bacterial OTUs made up more than 75% of all bacterial sequences. The most abundant OTU was Sphingomonas sp. which comprised 17% of all bacterial sequences. The most abundant bacterial genera were attributed to distinctly different areas of origin, suggesting highly heterogeneous sources for bioaerosols of marine and coastal environments. Furthermore, the bacterial community was clearly affected by two environmental parameters - temperature as a function of wind direction and the sampling location itself. However, a comparison of the wind directions during the sampling and calculated backward trajectories underlined the need for more detailed information on environmental parameters for bioaerosol investigations. The current findings support the assumption of a bacterial core community in the atmosphere. They may be emitted from strong aerosolizing sources, probably being mixed and dispersed over long distances.

Das Projekt „Müll im Meer“ bereitet Expertenwissen zu Strategien der Probennahme, Analytik und Quantifizierung von Mikroplastik im Meer didaktisch mit vier Kooperationspartnern auf. Ziel ist es, fundierte und praxisorientierte Lernmodule für Schulen und außerschulische Lernorte zu entwickeln. Schülerinnen und Schüler der Sekundarstufe II führen diese in vier bis fünf Tagen durch. Die Lernmodule werden thematisch in naturwissenschaftliche Fächer integriert und sind im Zusammenhang mit Umweltschutz und nachhaltiger Nutzung von Ressourcen zu behandeln.

© 2017 Duhaime, Solonenko, Roux, Verberkmoes, Wichels and Sullivan. Viruses influence the ecology and evolutionary trajectory of microbial communities. Yet our understanding of their roles in ecosystems is limited by the paucity of model systems available for hypothesis generation and testing. Further, virology is limited by the lack of a broadly accepted conceptual framework to classify viral diversity into evolutionary and ecologically cohesive units. Here, we introduce genomes, structural proteomes, and quantitative host range data for eight Pseudoalteromonas phages isolated from Helgoland (North Sea, Germany) and use these data to advance a genome-based viral operational taxonomic unit (OTU) definition. These viruses represent five new genera and inform 498 unaffiliated or unannotated protein clusters (PCs) from global virus metagenomes. In a comparison of previously sequenced Pseudoalteromonas phage isolates (n = 7) and predicted prophages (n = 31), the eight phages are unique. They share a genus with only one other isolate, Pseudoalteromonas podophage RIO-1 (East Sea, South Korea) and two Pseudoalteromonas prophages. Mass-spectrometry of purified viral particles identified 12-20 structural proteins per phage. When combined with 3-D structural predictions, these data led to the functional characterization of five previously unidentified major capsid proteins. Protein functional predictions revealed mechanisms for hijacking host metabolism and resources. Further, they uncovered a hybrid sipho-myovirus that encodes genes for Mu-like infection rarely described in ocean systems. Finally, we used these data to evaluate a recently introduced definition for virus populations that requires members of the same population to have >95% average nucleotide identity across at least 80% of their genes. Using physiological traits and genomics, we proposed a conceptual model for a viral OTU definition that captures evolutionarily cohesive and ecologically distinct units. In this trait-based framework, sensitive hosts are considered viral niches, while host ranges and infection efficiencies are tracked as viral traits. Quantitative host range assays revealed conserved traits within virus OTUs that break down between OTUs, suggesting the defined units capture niche and fitness differentiation. Together these analyses provide a foundation for model system-based hypothesis testing that will improve our understanding of marine copiotrophs, as well as phage-host interactions on the ocean particles and aggregates where Pseudoalteromonas thrive.

Carbohydrates represent an important fraction of labile and semi-labile marine organic matter that is mainly comprised of exopolymeric substances derived from phytoplankton exudation and decay. This study investigates the composition of total combined carbohydrates (tCCHO; >1 kDa) and the community development of free-living (0.2–3 μm) and particle-associated (PA) (3–10 μm) bacterioplankton during a spring phytoplankton bloom in the southern North Sea. Furthermore, rates were determined for the extracellular enzymatic hydrolysis that catalyzes the initial step in bacterial organic matter remineralization. Concentrations of tCCHO greatly increased during bloom development, while the composition showed only minor changes over time. The combined concentration of glucose, galactose, fucose, rhamnose, galactosamine, glucosamine, and glucuronic acid in tCCHO was a significant factor shaping the community composition of the PA bacteria. The richness of PA bacteria greatly increased in the post-bloom phase. At the same time, the increase in extracellular β-glucosidase activity was sufficient to explain the observed decrease in tCCHO, indicating the efficient utilization of carbohydrates by the bacterioplankton community during the post-bloom phase. Our results suggest that carbohydrate concentration and composition are important factors in the multifactorial environmental control of bacterioplankton succession and the enzymatic hydrolysis of organic matter during phytoplankton blooms.

Since the 1950s more than 6.1 billion tons of plastics have been produced. It has been estimated that about 10% of this amount will be deposited long-term in theOceans. The problem is highlighted by several currentstudies using different environmental sampling protocols and analytical methods. Effects of this anthropogenic litter on the environment and organisms are heavily on debate, emphasizing the need to transfer this knowledge to young educated people and to fuel educational programs. The school lab OPENSEA at the Alfred-Wegener-Institute on Helgoland started a joint high school project on marine plastic litter in cooperation with the experts of the marine microplastics group at AWI to link science and education more closely. Based on the OSPAR protocol for beach monitoring of marine litter we developed an experimental set up focusing on sampling and identification of plastic litter on beaches, shores and in sediments in the course of the OPENSEA science and education program for grammar and high school scholars. This monitoring provides environmental data on marine plastic litter and will be integrated in a long term data monitoring program in the course of a citizen science study. In addition we plan to integrate also smaller plastic particles into the project. Fractionated sediment samples will be screened for particles > 0.5mm, which then will be analyzed by ATR-FT-IR. These educational activities, with a strong link to the latest science and to sophisticated technology will raise the awareness of younger people for the marine litter problematic. We aim at increasingtheir concerns after taking part in this program. We will present background information, sampling strategies, identification efforts and results based on this scholar science project.

Copepods can be associated with different kinds and different numbers of bacteria. This was already shown in the past with culture-dependent microbial methods or microscopy and more recently by using molecular tools. In our present study, we investigated the bacterial community of four frequently occurring copepod species, Acartia sp., Temora longicornis, Centropages sp. and Calanus helgolandicus from Helgoland Roads (North Sea) over a period of 2 years using DGGE (denaturing gradient gel electrophoresis) and subsequent sequencing of 16S-rDNA fragments. To complement the PCR-DGGE analyses, clone libraries of copepod samples from June 2007 to 208 were generated. Based on the DGGE banding patterns of the two years survey, we found no significant differences between the communities of distinct copepod species, nor did we find any seasonality. Overall, we identified 67 phylotypes (>97 % similarity) falling into the bacterial phyla of Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. The most abundant phylotypes were affiliated to the Alphaproteobacteria. In comparison with PCR-DGGE and clone libraries, phylotypes of the Gammaproteobacteria dominated the clone libraries, whereas Alphaproteobacteria were most abundant in the PCR-DGGE analyses.

We investigated the occurrence of Planktotalea frisia strain SH6-1(T), a member of the Roseobacter clade, in the North Sea, and interactions with phytoplankton algae with a special emphasis on the carbohydrate metabolisms. This bacterium was present in May 2006 throughout the North Sea. Planktotalea frisia SH6-1 was further present in the German Bight between February and early July, with distinct peaks during and after phytoplankton blooms. The highest abundances, as detected by quantitative PCR, were 0.5-0.9% of total bacterial abundance. Comparison by catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) with a set of highly specific probes confirmed the high values in one sample. Between mid-July and October, P. frisia SH6-1 was not detected throughout the North Sea. Experimental studies in which P. frisia SH6-1 was grown in the presence of axenic cultures of the algae Phaeocystis globosa, Leptocylindrus danicus and Thalassiosira rotula exhibited distinctly different responses, with the best growth together with P. globosa and T. rotula and very low growth together with L. danicus. The algae greatly differed in the composition of their exuded carbohydrates and in the fact that P. frisia SH6-1 was rather selective in consumption of algae, suggesting that the distinct carbohydrate metabolisms are a key feature to explain the seasonal occurrence of this bacterium in the North Sea.

Marine yeasts play an important role in biodegradation and nutrient cycling and are often associated with marine flora and fauna. They show maximum growth at pH levels lower than present-day seawater pH. Thus, contrary to many other marine organisms, they may actually profit from ocean acidification. Hence, we conducted a microcosm study, incubating natural seawater from the North Sea at present-day pH (8.10) and two near-future pH levels (7.81 and 7.67). Yeasts were isolated from the initial seawater sample and after 2 and 4 weeks of incubation. Isolates were classified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and representative isolates were identified by partial sequencing of the large subunit rRNA gene. From the initial seawater sample, we predominantly isolated a yeast-like filamentous fungus related to Aureobasidium pullulans, Cryptococcus sp., Candida sake, and various cold-adapted yeasts. After incubation, we found more different yeast species at near-future pH levels than at present-day pH. Yeasts reacting to low pH were related to Leucosporidium scottii, Rhodotorula mucilaginosa, Cryptococcus sp., and Debaryomyces hansenii. Our results suggest that these yeasts will benefit from seawater pH reductions and give a first indication that the importance of yeasts will increase in a more acidic ocean.

The increase in atmospheric carbon dioxide (CO2) results in acidification of the oceans, expected to lead to the fastest drop in ocean pH in the last 300 million years, if anthropogenic emissions are continued at present rate. Due to higher solubility of gases in cold waters and increased exposure to the atmosphere by decreasing ice cover, the Arctic Ocean will be among the areas most strongly affected by ocean acidification. Yet, the response of the plankton community of high latitudes to ocean acidification has not been studied so far. This work is part of the Arctic campaign of the European Project on Ocean Acidification (EPOCA) in 2010, employing 9 in situ mesocosms of about 45 000 l each to simulate ocean acidification in Kongsfjorden, Svalbard (78°56.2' N 11°53.6' E). In the present study, we investigated effects of elevated CO2 on the composition and richness of particle attached (PA; >3 μm) and free living (FL; 0.2 μm) bacterial communities by Automated Ribosomal Intergenic Spacer Analysis (ARISA) in 6 of the mesocosms and the surrounding fjord, ranging from 185 to 1050 initial μatm pCO2. ARISA was able to resolve about 20–30 bacterial band-classes per sample and allowed for a detailed investigation of the explicit richness. Both, the PA and the FL bacterioplankton community exhibited a strong temporal development, which was driven mainly by temperature and phytoplankton development. In response to the breakdown of a picophytoplankton bloom (phase 3 of the experiment), number of ARISA-band classes in the PA-community were reduced at low and medium CO2 (∼180–600 μatm) by about 25%, while it was more or less stable at high CO2 (∼ 650–800 μatm). We hypothesise that enhanced viral lysis and enhanced availability of organic substrates at high CO2 resulted in a more diverse PA-bacterial community in the post-bloom phase. Despite lower cell numbers and extracellular enzyme activities in the post-bloom phase, bacterial protein production was enhanced in high CO2-treatments, suggesting a positive effect of community richness on this function and on carbon cycling by bacteria.

Res_por:Entendendo o turismo como um fenomeno sociologico que corresponde a satisfacao de necessidades de evasao, emocao, crescimento pessoal ou reconhecimento social, a comunicacao turistica deve defi nir estrategias assentes em modelos experienciais (Schmitt, 1999) e fornecer experiencias que satisfacam as necessidades e o desejo dos clientes. Os estudos em que baseamos este artigo (Gentile et al, 2007; Schmitt et al, 2013; Schmitt, Rogers e Vrotsos, 2003; entre outros) sugerem que a comunicacao experiencial e a que tem demonstrado melhores resultados como fenomeno persuasor do consumidor e esta por detras da aura de produtos e servicos lideres de venda em mercados desenvolvidos. O presente texto aborda um aspeto especifi co da comunicacao turistica, em concreto o modelo de comunicacao e o marketing experiencial. Esta estruturado em tres partes: iniciamos com uma abordagem teorica relacionando o turismo e as experiencias, posteriormente analisamos a comunicacao e o marketing experiencial atraves da obra selecionada de Bernd Schmitt e fi nalmente, ilustramos com um estudo de caso de comunicacao turistica: a cadeia de hoteis-experiencia, ME by Melia, onde se aprecia a importância e o signifi cado da experiencia sensorial e dos sentimentos esteticos na comunicacao com o cliente.

Marine microbial biogeography has been studied intensively; however few studies address community variation across temporal and spatial scales simultaneously so far. Here we present a yearlong study investigating the dynamics of the free-living and particle-attached bacterioplankton community across a 100 km transect in the German Bight reaching from the Elbe estuary towards the open North Sea. Community composition was assessed using automated ribosomal intergenic spacer analysis and linked to environmental parameters applying multivariate statistical techniques. Results suggest that the spatial variation of the bacterioplankton community is defined by hydrographic current conditions, which separate the inner German Bight from the open North Sea and lead to pronounced differences in the coastal and offshore bacterioplankton community. However this spatial variation is overwhelmed by a strong temporal variation which is triggered by temperature as the main driving force throughout the whole transect. Variation in the free-living community was predominantly driven by temperature, whereas the particle-attached community exhibited stronger spatial variation patterns.

Draft genomes are presented for 6 Pseudoalteromonas sp. strains isolated from surface waters at Kabeltonne, Helgoland, a long-term ecological research station in the North Sea. These strains contribute knowledge of the genomic underpinnings of a developing model system to study phage-host dynamics of a particle-associated ocean copiotroph.

The taxonomic composition of biofilms on marine microplastics is widely unknown. Recent sequencing results indicate that potentially pathogenic Vibrio spp. might be present on floating microplastics. Hence, these particles might function as vectors for the dispersal of pathogens. Microplastics and water samples collected in the North and Baltic Sea were subjected to selective enrichment for pathogenic Vibrio species. Bacterial colonies were isolated from CHROMagar™Vibrio and assigned to Vibrio spp. on the species level by MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionisation - Time of Flight Mass Spectrometry). Respective polymers were identified by ATR FT-IR (Attenuated Total Reflectance Fourier Transform - Infrared Spectroscopy). We discovered potentially pathogenic Vibrio parahaemolyticus on a number of microplastic particles, e.g. polyethylene, polypropylene and polystyrene from North/Baltic Sea. This study confirms the indicated occurrence of potentially pathogenic bacteria on marine microplastics and highlights the urgent need for detailed biogeographical analyses of marine microplastics.

Blooming Succession Algal blooms in the ocean will trigger a succession of microbial predators and scavengers. Teeling et al. (p. 608 ) used a combination of microscopy, metagenomics, and metaproteomics to analyze samples from a North Sea diatom bloom over time. Distinct steps of polysaccharide degradation and carbohydrate uptake could be assigned to clades of Flavobacteria and Gammaproteobacteria, which differ profoundly in their transporter profiles and their uptake systems for phosphorus. The phytoplankton/bacterioplankton coupling in coastal marine systems is of crucial importance for global carbon cycling. Bacterioplankton clade succession following phytoplankton blooms may be predictable enough that it can be included in models of global carbon cycling.

Bacteria of the genus Vibrio are an important component of marine ecosystems worldwide. The genus harbors several human pathogens, for instance the species Vibrio parahaemolyticus, a main cause for foodborne gastroenteritis in Asia and the USA. Pathogenic V. parahaemolyticus strains emerged also in Europe, but little is known about the abundance, pathogenicity and ecology of V. parahaemolyticus especially in Northern European waters. This study focuses on V. parahaemolyticus and its close relative Vibrio alginolyticus in the North Sea (Helgoland Roads, Germany). Free-living, plankton-attached and shellfish-associated Vibrio spp. were quantified between May 2008 and January 2010. CFUs up to 4.3 × 10(3) N l(-1) and MPNs up to 240 N g(-1) were determined. Phylogenetic classification based on rpoB gene sequencing revealed V. alginolyticus as the dominant Vibrio species at Helgoland Roads, followed by V. parahaemolyticus. We investigated the intraspecific diversity of V. parahaemolyticus and V. alginolyticus using ERIC-PCR. The fingerprinting disclosed three distinct groups at Helgoland Roads, representing V. parahaemolyticus, V. alginolyticus and one group in between. The species V. parahaemolyticus occurred mainly in summer months. None of the strains carried the virulence-associated genes tdh or trh. We further analyzed the influence of nutrients, secchi depth, temperature, salinity, chlorophyll a and phytoplankton on the abundance of Vibrio spp. and the population structure of V. parahaemolyticus. Spearman Rank analysis revealed that particularly temperature correlated significantly with Vibrio spp. numbers. Based on multivariate statistical analyses we report that the V. parahaemolyticus population was structured by a complex combination of environmental parameters. To further investigate these influences is the key to understanding the dynamics of Vibrio spp. in temperate European waters, where this microbial group and especially the pathogenic species, are likely to gain in importance.

Although spirochetes were first detected in crystalline styles of bivalves more than 100 years ago, little is known about the characteristics of these consortia (commensalism or parasitism). The presence of spirochetes in bivalves can so far not be generalized. The purpose of this study was the detection and phylogenetic identification of spirochetes associated with crystalline styles of different marine bivalve species collected in temperate regions and Antarctica. Polymerase chain reaction amplification of spirochete 16S ribosomal gene sequences was performed. 16S ribosomal gene clones were identified by phylogenetic analysis, and the variability within each bivalve species was determined. The spirochetes were mainly related to yet uncultured or potentially pathogenic spirochetes from the marine environment. All identified spirochete clones fell into 2 families: the Spirochaetaceae with 2 genera, Cristispira and Spirochaeta, and the Brachyspiraceae, with the genus Braehyspira. The diversity of ...

Climate change and marine traffic lead to changing species communities in the oceans. Due to increasing seawater temperatures, pathogenic Vibrio species could become significant even in temperate waters. We classified mesophilic Vibrio isolates from the German Bight (North Sea) using a polyphasic approach with special emphasis on Vibrio parahaemolyticus. Matrix-assisted laser desorption/ionization time-of-flight MS was used as a primary screen to classify isolates, 16S rRNA gene and rpoB gene sequencing to identify species. Potential V. parahaemolyticus isolates were screened for regulatory or virulence-related genes (toxR, tlh, tdh, trh). To investigate genomic diversity, we applied repetitive-sequence-based PCRs. Results were evaluated and methods compared using multivariate statistical analysis. Most isolates were classified as V. parahaemolyticus or Vibrio alginolyticus. Reliable differentiation between both species was achieved by rpoB sequencing and toxR detection. Among the fingerprinting methods, ERIC-PCR showed the highest discriminatory power, displaying three separated clusters. These clusters represent the species V. parahaemolyticus, V. alginolyticus and one group in between. The frequent detection of V. parahaemolyticus in the German Bight reveals the urgency for further monitoring. In this context, a polyphasic approach, such as defined in this study, is needed to differentiate populations of V. parahaemolyticus and V. alginolyticus.

The class Cryptophyceae (Division Cryptophyta) contains ecologically relevant species, which are widespread in aquatic environments. However, classification, identification, and enumeration of cryptophytes are challenged by a morphology that must be usually examined with EM to permit species identification. The quantitative importance of this group has been revealed by HPLC data. But ecological information assessing the occurrence or seasonality of cryptophytes in the marine environment is still scarce. Molecular techniques allow for a refined assessment of taxonomically challenging taxa, such as the cryptophytes. In our laboratory, a Phylochip was developed to facilitate and refine the assessment of cryptophyte microalgae. Here, we present the results of an environmental study that took advantage of the Phylochip. The study was designed to elucidate the seasonality and contribution of cryptophytes to phytoplankton structure in the German Bight. The occurrence of cryptophytes in total plankton versus the picoplankton fraction was assessed with the Phylochip between the years 2004 and 2006. Our data indicate that cryptophytes are an important and constant contributor to phytoplankton structure of the German Bight, especially in the picoplankton fraction.

Marine phages have an astounding global abundance and ecological impact. However, little knowledge is derived from phage genomes, as most of the open reading frames in their small genomes are unknown, novel proteins. To infer potential functional and ecological relevance of sequenced marine Pseudoalteromonas phage H105/1, two strategies were used. First, similarity searches were extended to include six viral and bacterial metagenomes paired with their respective environmental contextual data. This approach revealed 'ecogenomic' patterns of Pseudoalteromonas phage H105/1, such as its estuarine origin. Second, intrinsic genome signatures (phylogenetic, codon adaptation and tetranucleotide (tetra) frequencies) were evaluated on a resolved intra-genomic level to shed light on the evolution of phage functional modules. On the basis of differential codon adaptation of Phage H105/1 proteins to the sequenced Pseudoalteromonas spp., regions of the phage genome with the most 'host'-adapted proteins also have the strongest bacterial tetra signature, whereas the least 'host'-adapted proteins have the strongest phage tetra signature. Such a pattern may reflect the evolutionary history of the respective phage proteins and functional modules. Finally, analysis of the structural proteome identified seven proteins that make up the mature virion, four of which were previously unknown. This integrated approach combines both novel and classical strategies and serves as a model to elucidate ecological inferences and evolutionary relationships from phage genomes that typically abound with unknown gene content.

Marine zooplanktic organisms, such as copepods, are usually associated with large numbers of bacteria. Some of these bacteria live attached to copepods’ exoskeleton, while others prevail in their intestine and faecal pellets. Until now, general conclusions concerning the identity of these bacteria are problematic since the majority of previous studies focused on cultivable bacteria only. Hence, to date little is known on whether copepod genera or species harbour distinct bacterial populations and about the nature of this association. To shed more light on these copepod/bacteria consortia, the focus of this study was the development and evaluation of a suitable approach to extract bacterial DNA from different North Sea copepod genera. Furthermore, the bacterial DNA was analysed by PCR-DGGE and subsequent sequencing of excised bands. The result of this work was an appropriate extraction method for batches of ten to one copepod specimens and offered first insights as to which bacteria are attached to the copepods Acartia sp. and Temora sp. from Helgoland Roads (German Bight) and a laboratory-grown Acartia tonsa culture. It revealed the prevalence of Alphaproteobacteria.

The Helgoland Roads time series is one of the richest temporal marine data sets available. Running since 1962, it documents changes for phytoplankton, salinity, Secchi disc depths and macronutrients. Uniquely, the data have been carefully quality controlled and linked to relevant meta-data, and the pelagic time series is further augmented by zooplankton, intertidal macroalgae, macro-zoobenthos and bacterioplankton data. Data analyses have shown changes in hydrography and biota around Helgoland. In the late 1970s, water inflows from the south-west to the German Bight increased with a corresponding increase in flushing rates. Salinity and annual mean temperature have also increased since 1962 and the latter by an average of 1.67°C. This has influenced seasonal phytoplankton growth causing significant shifts in diatom densities and the numbers of large diatoms (e. g. Coscinodiscus wailesii). Changes in zooplankton diversity have included the appearance of the ctenophore Mnemiopsis leidyi. The macroalgal community also showed an increase in green algal and a decrease in brown algal species after 1959. Over 30 benthic macrofaunal species have been newly recorded at Helgoland over the last 20 years, with a distinct shift towards southern species. These detailed data provide the basis for long-term analyses of changes on many trophic levels at Helgoland Roads.

Dinoroseobacter shibae DFL12(T), a member of the globally important marine Roseobacter clade, comprises symbionts of cosmopolitan marine microalgae, including toxic dinoflagellates. Its annotated 4 417 868 bp genome sequence revealed a possible advantage of this symbiosis for the algal host. D. shibae DFL12(T) is able to synthesize the vitamins B(1) and B(12) for which its host is auxotrophic. Two pathways for the de novo synthesis of vitamin B(12) are present, one requiring oxygen and the other an oxygen-independent pathway. The de novo synthesis of vitamin B(12) was confirmed to be functional, and D. shibae DFL12(T) was shown to provide the growth-limiting vitamins B(1) and B(12) to its dinoflagellate host. The Roseobacter clade has been considered to comprise obligate aerobic bacteria. However, D. shibae DFL12(T) is able to grow anaerobically using the alternative electron acceptors nitrate and dimethylsulfoxide; it has the arginine deiminase survival fermentation pathway and a complex oxygen-dependent Fnr (fumarate and nitrate reduction) regulon. Many of these traits are shared with other members of the Roseobacter clade. D. shibae DFL12(T) has five plasmids, showing examples for vertical recruitment of chromosomal genes (thiC) and horizontal gene transfer (cox genes, gene cluster of 47 kb) possibly by conjugation (vir gene cluster). The long-range (80%) synteny between two sister plasmids provides insights into the emergence of novel plasmids. D. shibae DFL12(T) shows the most complex viral defense system of all Rhodobacterales sequenced to date.

Heterotrophic marine bacteria utilise a wide range of carbon sources. Recently, techniques were developed to link bacterial identity and physiological capacity of microorganisms within natural communities. One of these methods is stable isotope probing (SIP) which allows an identification of active microorganisms using particular growth substrates. In this study, we present the first attempt to analyse bacterial communities associated with microalgae by rRNA-SIP. This approach was used to analyse bacterial populations consuming algal products of Thalassiosira rotula by applying SIP followed by reverse transcription of 16S rRNA and denaturing gradient gel electrophoresis. Generally, our results indicate that bacteria which consume algal products can be detected by isotope arrays coupled with fingerprinting methods.

Bacterioplankton dynamics at Helgoland Roads (54°11.3′N, 7°54.0′E) in the North Sea over the winter–spring transition were investigated. The bacterial community was analyzed and correlated with phytoplankton community data and abiotic parameters. The community structure was analyzed by ribosomal intergenic spacer analysis (RISA) and by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes followed by DNA sequence analysis. The linkage of abiotic and biotic environmental factors and bacterial community as well as phylotypes (sequenced DGGE bands) was analyzed by the ordination technique of canonical correspondence analysis (CCA). Generally, an influence of temperature and phytoplankton on the bacterial community during the sampling period was observed. Additionally, multivariate analysis by factors revealed an influence on specific bacterial phylotypes of these factors. Overall, results indicate that changes in the bacterial community were caused not only by abiotic factors but also by the phytoplankton community.

The dynamics of coastal marine microbial communities are driven by seasonally changing abiotic and biotic factors as well as by rapidly occurring short-term changes such as river fresh water influxes or phytoplankton blooms. We examined the variability of the free-living bacterioplankton at Helgoland Roads (German Bight, North Sea) over a period of one year with high temporal and taxonomic resolution to reveal variation patterns and main influencing factors. 16S rRNA gene tag sequencing of the bacterioplankton community hints at annual recurrence and resilience of few main taxa belonging to Alphaproteobacteria, Betaproteobacteria, Flavobacteriia, Acidimicrobiia and Thermoplasmata. Multiple regression analyses with various environmental factors revealed changes in water current patterns and resulting phytoplankton blooms as the main driving factors for short-term variation and temperature as the overlying factor for seasonal variation. Comparison of bacterioplankton successions during spring and summer phytoplankton blooms revealed the same dominating Flavobacteriia operational taxonomic units (OTUs) but shifts in Roseobacter related OTUs (Alphaproteobacteria) and SAR92 clade members (Gammaproteobacteria). Network analysis suggests that during spring and summer phytoplankton blooms temperature-dependent guilds are formed. In conclusion, our data imply that short-term bacterioplankton successions in response to phytoplankton blooms are indirectly affected by temperature, which is a major niche-defining factor in the German Bight.

Intense research has been conducted on jellyfish and ctenophores in recent years. They are increasingly recognized as key elements in the marine ecosystem that serve as critical indicators and drivers of ecosystem performance and change. However, the bacterial community associated with ctenophores is still poorly investigated. Based on automated ribosomal intergenic spacer analysis (ARISA) and 16S ribosomal RNA gene amplicon pyrosequencing, we investigated bacterial communities associated with the frequently occurring ctenophore species Mnemiopsis leidyi, Beroe sp., Bolinopsis infundibulum and Pleurobrachia pileus at Helgoland Roads in the German Bight (North Sea). We observed significant differences between the associated bacterial communities of the different ctenophore species based on ARISA patterns. With respect to bacterial taxa, all ctenophore species were dominated by Proteobacteria as revealed by pyrosequencing. Mnemiopsis leidyi and P. pileus mainly harboured Gammaproteobacteria, with Marinomonas as the dominant phylotype of M. leidyi. By contrast, Pseudoalteromonas and Psychrobacter were the most abundant Gammaproteobacteria in P. pileus. Beroe sp. was mainly dominated by Alphaproteobacteria, particularly by the genus Thalassospira. For B. infundibulum, the bacterial community was composed of Alphaproteobacteria and Gammaproteobacteria in equal parts, which consisted of the genera Thalassospira and Marinomonas. In addition, the bacterial communities associated with M. leidyi display a clear variation over time that needs further investigation. Our results indicate that the bacterial communities associated with ctenophores are highly species- specific.