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  • 1
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    Small Changes in pH Have Direct Effects on Marine Bacterial Community Composition: A Microcosm Approach (2012)
    Public Library of Science
    In:  PLoS ONE, 7 (10). e47035.
    Details
    Publication Date: 2014-06-11
    Description: As the atmospheric CO2 concentration rises, more CO2 will dissolve in the oceans, leading to a reduction in pH. Effects of ocean acidification on bacterial communities have mainly been studied in biologically complex systems, in which indirect effects, mediated through food web interactions, come into play. These approaches come close to nature but suffer from low replication and neglect seasonality. To comprehensively investigate direct pH effects, we conducted highly-replicated laboratory acidification experiments with the natural bacterial community from Helgoland Roads (North Sea). Seasonal variability was accounted for by repeating the experiment four times (spring, summer, autumn, winter). Three dilution approaches were used to select for different ecological strategies, i.e. fast-growing or low-nutrient adapted bacteria. The pH levels investigated were in situ seawater pH (8.15–8.22), pH 7.82 and pH 7.67, representing the present-day situation and two acidification scenarios projected for the North Sea for the year 2100. In all seasons, both automated ribosomal intergenic spacer analysis and 16S ribosomal amplicon pyrosequencing revealed pH-dependent community shifts for two of the dilution approaches. Bacteria susceptible to changes in pH were different members of Gammaproteobacteria, Flavobacteriaceae, Rhodobacteraceae, Campylobacteraceae and further less abundant groups. Their specific response to reduced pH was often context-dependent. Bacterial abundance was not influenced by pH. Our findings suggest that already moderate changes in pH have the potential to cause compositional shifts, depending on the community assembly and environmental factors. By identifying pH-susceptible groups, this study provides insights for more directed, in-depth community analyses in large-scale and long-term experiments.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1371/journal.pone.0047035
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach (2013)
    Springer
    In:  Helgoland Marine Research, 67 (4). pp. 607-621.
    Details
    Publication Date: 2014-04-22
    Description: 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.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s10152-013-0348-1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Marine fungi may benefit from ocean acidification (2013)
    Inter Research
    In:  Aquatic Microbial Ecology, 69 (1). pp. 59-67.
    Details
    Publication Date: 2014-04-22
    Description: Recent studies have discussed the consequences of ocean acidification for bacterial processes and diversity. However, the decomposition of complex substrates in marine environments, a key part of the flow of energy in ecosystems, is largely mediated by marine fungi. Although marine fungi have frequently been reported to prefer low pH levels, this group has been neglected in ocean acidification research. We present the first investigation of direct pH effects on marine fungal abundance and community structure. In microcosm experiments repeated in 2 consecutive years, we incubated natural North Sea water for 4 wk at in situ seawater pH (8.10 and 8.26), pH 7.82 and pH 7.67. Fungal abundance was determined by colony forming unit (cfu) counts, and fungal community structure was investigated by the culture-independent fingerprint method Fungal Automated Ribosomal Intergenic Spacer Analysis (F-ARISA). Furthermore, pH at the study site was determined over a yearly cycle. Fungal cfu were on average 9 times higher at pH 7.82 and 34 times higher at pH 7.67 compared to in situ seawater pH, and we observed fungal community shifts predominantly at pH 7.67. Currently, surface seawater pH at Helgoland Roads remains 〉8.0 throughout the year; thus we cannot exclude that fungal responses may differ in regions regularly experiencing lower pH values. However, our results suggest that under realistic levels of ocean acidification, marine fungi will reach greater importance in marine biogeochemical cycles. The rise of this group of organisms will affect a variety of biotic interactions in the sea.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3354/ame01622
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    The ocean sampling day consortium (2015)
    Oxford Univ. Press
    In:  GigaScience, 4 (1). Art.Nr. 27.
    Details
    Publication Date: 2019-09-23
    Description: Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    DOI: 10.1186/s13742-015-0066-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Combined Carbohydrates Support Rich Communities of Particle-Associated Marine Bacterioplankton (2017)
    Frontiers
    In:  Frontiers in Microbiology, 8 . Art.Nr. 65.
    Details
    Publication Date: 2020-02-06
    Description: 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.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3389/fmicb.2017.00065
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Schoolchildren discover hotspots of floating plastic litter in rivers using a large-scale collaborative approach (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: 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.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach
    PANGAEA
    In:  Supplement to: Krause, Evamaria; Wichels, Antje; Erler, Rene; Gerdts, Gunnar (2013): Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach. Helgoland Marine Research, 67(4), 607-621, https://doi.org/10.1007/s10152-013-0348-1
    Details
    Publication Date: 2023-05-12
    Description: 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.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; North Atlantic
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
  • 8
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    Methane concentration and oxidation in the Lena Delta, September 2013 (2016)
    PANGAEA
    In:  Supplement to: Bussmann, Ingeborg; Hackbusch, Steffen; Schaal, Patrick; Wichels, Antje (2017): Methane distribution and oxidation around the Lena Delta in summer 2013. Biogeosciences, 14(21), 4985-5002, https://doi.org/10.5194/bg-14-4985-2017
    Details
    Publication Date: 2023-07-08
    Description: The Lena River is one of the biggest Russian rivers draining into the Laptev Sea. Due to predicted increasing temperatures, the permafrost areas surrounding the Lena Delta will melt at increasing rates. With this melting, high amounts of methane will reach the waters of the Lena and the adjacent Laptev Sea. Methane oxidation by methanotrophic bacteria is the only biological way to reduce methane concentrations within the system. However, the polar estuary of the Lena River is a challenging environment for bacteria, with strong fluctuations in salinity and temperature. We determined the activity (tracer method) and the abundance (qPCR) of aerobic methanotrophic bacteria. We described the methanotrophic population with MISA; as well as the methane distribution (head space) and other abiotic parameters in the Lena Delta in September 2013. In 'riverine water' (S 〈5) we found a median methane concentration of 22 nM, in 'mixed water' (5 〈 S 〈 20) the median methane concentration was 19 nM and in 'polar water' (S 〉 20) a median 28 nM was observed. The Lena River was not the methane source for surface water, and bottom water methane concentrations were mainly influenced by the concentration in surface sediments. However, the methane oxidation rate in riverine and polar water was very similar (0.419 and 0.400 nM/d), but with a higher relative abundance of methanotrophs and a higher 'estimated diversity' with respect to MISA OTUs in the 'rivine water' as compared to 'polar water'. The turnover times of methane ranged from 167 d in 'mixed water', 91 d in 'riverine water' and only 36 d in 'polarwater'. Also the environmental parameters influencing the methane oxidation rate and the methanotrophic population differed between the water masses. Thus we postulate a riverine methanotrophic population limited by sub-optimal temperatures and substrate concentrations and a polar methanotrophic population being well adapted to the cold and methane poor environment, but limited by the nitrogen content. The diffusive methane flux into the atmosphere ranged from 4 -163 µmol m2 d-1 (median 24). For the total methane inventory of the investigated area, the diffusive methane flux was responsible for 8% loss, compared to only 1% of the methane consumed by the methanotrophic bacteria within the system.
    Keywords: AWI_Coast; AWI Arctic Land Expedition; Bacteria, methane oxidizing; Coastal Ecology @ AWI; Date/Time of event; DEPTH, water; Elevation of event; Event label; Laptev Sea; Latitude of event; Lena2013; Longitude of event; Methane; Methane oxidation rate; Methane oxidation rate, standard deviation; MULT; Multiple investigations; Quantitative real-time polymerase chain reaction (q-PCR); Radio 3H-CH4 tracer technique; RU-Land_2013_Lena; T1-1302; T1-1303; T1-1304; T1-1305; T1-1306; T1-1307; T1-3X-1; T4-1301; T4-1303; T4-1304; T4-1305; T5-1301; T5-1303; T5-1304; T6-1301; T6-1302; T6-1303; T6-1304; T6-1305; Turnover rate, methane; Turnover rate, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 180 data points
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    DATA PANGAEA
  • 9
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    Mycoplankton diversity in the Elbe River (2021)
    PANGAEA
    Details
    Publication Date: 2024-02-24
    Description: Rivers are important transport systems for nutrients and organic material and thus influence biogeochemical cycles and food web structures. Microorganismal biodiversity is an important parameter for the ecological balance of river ecosystems. Despite the knowledge that freshwater fungi perform important ecological functions, there is scarcely any fungal data available for river systems. In this study, we address the fundamental question of how mycoplankton communities are structured and assembled over a longer river section with strong environmental gradients and anthropogenic pressure and what variables control on it. The mycoplankton communities from the shallow freshwater to the coastal-oceanic transition zone were analyzed based on 18S rRNA gene tag-sequencing and the observed patterns were related to environmental and spatial factors by multivariate statistics. Finally, the underlying assembly processes were revealed by Quantitative Process Estimates (QPE) method. The partitioning of mycoplankton communities deviated from the previously described patterns of fluvial microbial communities, triggered by a strong influence of local environmental conditions, which were partly under spatial control. The deepening of the Elbe River for improved navigation purpose seemed to have a strong secondary effect. The salinity gradient was the most explaining variable and zoosporic fungi showed higher sensitivity to high salinity levels. Consequently, none of the zoosporic taxon groups occurred solely in the marine environment. Significant differences were found in the assemblage processes with a dominance of environmental selection in the upstream region compared to undominated processes in downstream and coastal transition regions. The results suggest that fungi play various ecological roles along the diverse river sections and that their biotic interactions become more complex in the estuary. These results provide an important framework to help predict the functional consequences of changes in mycoplankton community structure and to help conserve microbial biodiversity in river ecosystems.
    Keywords: Ammonium; brackish; Carbon, organic, dissolved; Chlorophyll a; Date/Time of event; Elbe; Elbe_mycoplankton_1; Elbe_mycoplankton_10; Elbe_mycoplankton_11; Elbe_mycoplankton_12; Elbe_mycoplankton_13; Elbe_mycoplankton_14; Elbe_mycoplankton_15; Elbe_mycoplankton_16; Elbe_mycoplankton_17; Elbe_mycoplankton_18; Elbe_mycoplankton_19; Elbe_mycoplankton_2; Elbe_mycoplankton_20; Elbe_mycoplankton_21; Elbe_mycoplankton_22; Elbe_mycoplankton_23; Elbe_mycoplankton_24; Elbe_mycoplankton_3; Elbe_mycoplankton_4; Elbe_mycoplankton_5; Elbe_mycoplankton_6; Elbe_mycoplankton_7; Elbe_mycoplankton_8; Elbe_mycoplankton_9; Elbe river; Estuary; Event label; freshwater; Fungi; Latitude of event; Longitude of event; marine; Nitrate; Nitrite; Optional event label; pH; Phosphate; Salinity; Sample1; Sample10; Sample11; Sample12; Sample13; Sample14; Sample15; Sample16; Sample17; Sample18; Sample19; Sample2; Sample20; Sample21; Sample22; Sample23; Sample24; Sample3; Sample4; Sample5; Sample6; Sample7; Sample8; Sample9; Silicate; Temperature, water
    Type: Dataset
    Format: text/tab-separated-values, 232 data points
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    DATA PANGAEA
  • 10
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    Continuous thermosalinograph oceanography along HEINCKE cruise track HE495 (2018)
    PANGAEA
    In:  Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven
    Details
    Publication Date: 2024-01-12
    Keywords: AWI_PhyOce; CT; DATE/TIME; DEPTH, water; HE495; HE495-track; Heincke; LATITUDE; LONGITUDE; North Sea; Physical Oceanography @ AWI; Salinity; Temperature, water; Thermosalinograph; TSG; Underway cruise track measurements
    Type: Dataset
    Format: text/tab-separated-values, 518 data points
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    DATA PANGAEA
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