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  • American Association for the Advancement of Science  (2)
  • Elsevier  (2)
  • Frontiers Media  (2)
  • Springer  (2)
  • Wiley  (2)
  • AMER SOC LIMNOLOGY OCEANOGRAPHY  (1)
  • Inter-Research  (1)
Document type
Keywords
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    A nitrate-selective microelectrode based on a lipophilic derivative of iodocobalt(III)salen (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 595-598 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of iodo{2,2′-[1,2-octadecanediylbis(nitrilomethylidyne)]diphenolato}cobalt is described. Liquid membrane microelectrodes based on this carrier exhibit Nernstian behaviour with a selectivity sequence according to the Hofmeister series: I– 〉 NO3 – 〉 NO2 – 〉 Cl– 〉 HCO3 – 〉 AcO–. The selectivity coefficient of nitrate over nitrite and chloride amounts to –1.6 and –2.7, respectively. The detection limit for nitrate in water amounts to 10–5.2 mol/L. A nitrate profile measured in a nitrifying biofilm is presented as a practical application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051392
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Microbial effects on biofilm calcification, ambient water chemistry and stable isotope records in a highly supersaturated setting (Westerhöfer Bach, Germany) (2008)
    Elsevier
    In:  Palaeogeography, Palaeoclimatology, Palaeoecology, 262 (1-2). pp. 91-106.
    Details
    Publication Date: 2018-11-07
    Description: Cyanobacteria-dominated biofilms in a CO2-degassing karst-water creek (Westerhöfer Bach, Germany) were investigated with regard to the effects of microbial activity on CaCO3 precipitation, water chemistry of micro- and macroenvironments, stable isotopic records, and tufa fabric formation. Ex situ microelectrode measurements of pH, O2, Ca2+ and CO32− revealed that annually laminated calcified biofilms composed mainly of filamentous cyanobacteria (tufa stromatolites) strongly induced CaCO3 precipitation by photosynthesis under illumination, but inhibited precipitation by respiration in the dark. In contrast, endolithic cyanobacterial biofilms and mosses did not cause photosynthesis-induced precipitation under experimental conditions. No spontaneous precipitation occurred on bare limestone substrates, despite high calcite supersaturation of the ambient water. Mass balance calculations suggest that biofilm photosynthesis was responsible for 10–20% of Ca2+ loss in the creek, while the remaining Ca2+ loss derived from physicochemical precipitation on branches, leaves and as fine-grained calcite particles. Neither analysis of bulk water chemistry nor oxygen nor carbon stable isotopic records of the tufa stromatolites confirmed photosynthetic effects, despite the evident photosynthesis-induced calcite precipitation. Oxygen stable isotopic values reflected seasonal changes in water temperature, and carbon stable isotope values probably recorded carbon isotopic composition of dissolved inorganic carbon in the creek water. Annual lamination and fabric formation of the tufa stromatolites is suggested to vary with photosynthesis-induced calcite precipitation rates that are affected by temperature dependency of diffusion coefficients. Photosynthesis-induced precipitation resulted in encrusted cyanobacterial sheaths, reflecting syntaxial overgrowth of microcrystalline cyanobacterial tubes by microspar, instead of microcrystalline sheath impregnation, which was previously suggested as an indicator of photosynthesis-induced precipitation. Therefore, sheath impregnation or encrustation by CaCO3 cannot be used to distinguish photosynthesis-induced from physicochemically-induced CaCO3 precipitation.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.palaeo.2008.02.011
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Microsensor studies on Padina from a natural CO2 seep: implications of morphology on acclimation to low pH (2015)
    Wiley
    In:  Journal of Phycology, 51 (6). pp. 1106-1115.
    Details
    Publication Date: 2020-07-20
    Description: Low seawater pH can be harmful to many calcifying marine organisms, but the calcifying macroalgae Padina spp. flourish at natural submarine carbon dioxide seeps where seawater pH is low. We show that the microenvironment created by the rolled thallus margin of Padina australis facilitates supersaturation of CaCO3 and calcifi-cation via photosynthesis-induced elevated pH. Using microsensors to investigate oxygen and pH dynamics in the microenvironment of P. australis at a shallow CO2 seep, we found that, under saturating light, the pH inside the microenvironment (pHME) was higher than the external seawater (pHSW) at all pHSW levels investigated, and the difference (i.e., pHME − pHSW) increased with decreasing pHSW (0.9 units at pHSW 7.0). Gross photosynthesis (Pg) inside the microenvironment increased with decreasing pHSW, but algae from the control site reached a threshold at pH 6.5. Seep algae showed no pH threshold with respect to Pg within the pHSW range investigated. The external carbonic anhydrase (CA) inhibitor, acetazolamide, strongly inhibited Pg of P. australis at pHSW 8.2, but the effect was diminished under low pHSW (6.4–7.5), suggesting a greater dependence on membrane-bound CA for the dehydration of HCO3− ions during dissolved inorganic carbon uptake at the higher pHSW. In comparison, a calcifying green alga, Halimeda cuneata f. digitata, was not inhibited by AZ, suggesting efficient bicarbonate transport. The ability of P. australis to elevate pHME at the site of calcification and its strong dependence on CA may explain why it can thrive at low pHSW.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1111/jpy.12347
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Changes in microbial communities in coastal sediments along natural CO2gradients at a volcanic vent in Papua New Guinea (2015)
    Wiley
    In:  Environmental Microbiology, 17 (10). pp. 3678-3691.
    Details
    Publication Date: 2016-11-04
    Description: Natural CO2 venting systems can mimic conditions that resemble intermediate to high pCO2 levels as predicted for our future oceans. They represent ideal sites to investigate potential long-term effects of ocean acidification on marine life. To test whether microbes are affected by prolonged exposure to pCO2 levels, we examined the composition and diversity of microbial communities in oxic sandy sediments along a natural CO2 gradient. Increasing pCO2 was accompanied by higher bacterial richness and by a strong increase in rare members in both bacterial and archaeal communities. Microbial communities from sites with CO2 concentrations close to today's conditions had different structures than those of sites with elevated CO2 levels. We also observed increasing sequence abundance of several organic matter degrading types of Flavobacteriaceae and Rhodobacteraceae, which paralleled concurrent shifts in benthic cover and enhanced primary productivity. With increasing pCO2, sequences related to bacterial nitrifying organisms such as Nitrosococcus and Nitrospirales decreased, and sequences affiliated to the archaeal ammonia-oxidizing Thaumarchaeota Nitrosopumilus maritimus increased. Our study suggests that microbial community structure and diversity, and likely key ecosystem functions, may be altered in coastal sediments by long-term CO2 exposure to levels predicted for the end of the century.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
    DOI: 10.1111/1462-2920.12729
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Oxygen dynamics and transport in the Mediterranean sponge Aplysina aerophoba (2008)
    Springer
    In:  Marine Biology, 153 (6). pp. 1257-1264.
    Details
    Publication Date: 2019-01-10
    Description: The Mediterranean sponge Aplysina aerophoba kept in aquaria or cultivation tanks can stop pumping for several hours or even days. To investigate changes in the chemical microenvironments, we measured oxygen profiles over the surface and into the tissue of pumping and non-pumping A. aerophoba specimens with Clark-type oxygen microelectrodes (tip diameters 18–30 μm). Total oxygen consumption rates of whole sponges were measured in closed chambers. These rates were used to back-calculate the oxygen distribution in a finite-element model. Combining direct measurements with calculations of diffusive flux and modeling revealed that the tissue of non-pumping sponges turns anoxic within 15 min, with the exception of a 1 mm surface layer where oxygen intrudes due to molecular diffusion over the sponge surface. Molecular diffusion is the only transport mechanism for oxygen into non-pumping sponges, which allows total oxygen consumption rates of 6–12 μmol cm−3 sponge day−1. Sponges of different sizes had similar diffusional uptake rates, which is explained by their similar surface/volume ratios. In pumping sponges, oxygen consumption rates were between 22 and 37 μmol cm−3 sponge day−1, and the entire tissue was oxygenated. Combining different approaches of direct oxygen measurement in living sponges with a dynamic model, we can show that tissue anoxia is a direct function of the pumping behavior. The sponge-microbe system of A. aerophoba thus has the possibility to switch actively between aerobic and anaerobic metabolism by stopping the water flow for more than 15 min. These periods of anoxia will greatly influence physiological variety and activity of the sponge microbes. Detailed knowledge about the varying chemical microenvironments in sponges will help to develop protocols to cultivate sponge-associated microbial lineages and improve our understanding of the sponge-microbe-system
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-008-0905-3
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Suitability analysis and revised strategies for marine environmental carbon capture and storage (CCS) monitoring (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights • Approaches for CO2 leakage detection, attribution and quantification monitoring exist. • Many approaches cover multiple monitoring tasks simultaneously. • Sonars and chemical sensors on ships or AUVs can cover large areas. • Newer, more specific technologies can detect, verify and quantify smaller, localised leaks. Environmental monitoring of offshore Carbon Capture and Storage (CCS) complexes requires robust methodologies and cost-effective tools to detect, attribute and quantify CO2 leakage in the unlikely event it occurs from a sub-seafloor reservoir. Various approaches can be utilised for environmental CCS monitoring, but their capabilities are often undemonstrated and more detailed monitoring strategies need to be developed. We tested and compared different approaches in an offshore setting using a CO2 release experiment conducted at 120 m water depth in the Central North Sea. Tests were carried out over a range of CO2 injection rates (6 - 143 kg d−1) comparable to emission rates observed from abandoned wells. Here, we discuss the benefits and challenges of the tested approaches and compare their relative cost, temporal and spatial resolution, technology readiness level and sensitivity to leakage. The individual approaches demonstrate a high level of sensitivity and certainty and cover a wide range of operational requirements. Additionally, we refer to a set of generic requirements for site-specific baseline surveys that will aid in the interpretation of the results. Critically, we show that the capability of most techniques to detect and quantify leakage exceeds the currently existing legal requirements.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Thermal stress reduces pocilloporid coral resilience to ocean acidification by impairing control over calcifying fluid chemistry (2021)
    American Association for the Advancement of Science
    In:  EPIC3Science Advances, American Association for the Advancement of Science, 7
    Details
    Publication Date: 2021-01-25
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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    PAPER (OA)
  • 8
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    Oxygen budgets in subtidal arctic (Kongsfjorden, Svalbard) and temperate (Helgoland, North Sea) microphytobenthic communities (2014)
    Inter-Research
    In:  EPIC3Marine Ecology Progress Series, Inter-Research, 504, pp. 27-42, ISSN: 0171-8630
    Details
    Publication Date: 2019-07-16
    Description: We compared primary production and respiration of temperate (Helgoland, North Sea) and subtidal Arctic (Kongsfjorden, Svalbard) microphytobenthic communities during summer. The diatom communities were generally characterized as cosmopolitan, displayed no site specificity, and had similar chl a and fucoxanthin concentrations. Their net and gross photosynthesis rates and light adaptation intensities, derived from laboratory microsensor measurements, were also similar, despite differences in water temperature. Daily oxygen fluxes across the sediment− water interface were estimated by combining laboratory microprofile and planar optode measurements with in situ data on oxygen penetration and light dynamics. During the study period, the Svalbard sediments were on average net heterotrophic,while the Helgoland sediments were net autotrophic (−22.4 vs. 9.2 mmol O2 m−2 d−1). This was due to high infaunal abundance in the Svalbard sediments that caused high oxygen uptake rates in the sediments and consumption below the sediment euphotic zone. Additionally, bioirrigation of the sediment due to infaunal burrow ventilation was reduced by light; thus, the sedimentary oxygen inventory was reduced with increasing light. Conversely, light-enhanced the oxygen inventory in the Helgoland sediments. Oxygen dynamics in the Svalbard sediments were therefore dominated by bioirrigation, whereas in the Helgoland sediments they were dominated by photosynthetic oxygen production.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 9
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    Kelp deposition changes mineralization pathways and microbial communities in a sandy beach (2020)
    AMER SOC LIMNOLOGY OCEANOGRAPHY
    In:  EPIC3Limnology and Oceanography, AMER SOC LIMNOLOGY OCEANOGRAPHY, ISSN: 0024-3590
    Details
    Publication Date: 2020-09-07
    Description: We investigated the impact of kelp deposition on the geochemistry and microbial community composition of beach sands on the island of Helgoland (North Sea). The composition of the microbial community at a beach with regular kelp deposition appeared shaped by this regular input of organic material, as indicated by significantly higher proportions of aerobic degraders, fermenters, and sulfur cycling microorganisms. Rapid degradation of deposited kelp by this community leads to high levels of dissolved organic and inorganic carbon and nutrients, a lower pH and anoxia. Aerobic respiration, fermentation, Fe- and SO42- reduction and methanogenesis were strongly enhanced, with SO42- reduction being the main process in kelp degradation. SO42- reduction rates increased 20 to 25-fold upon addition of kelp. The main route of electrons from kelp to SO42- was not via CO and H2, as expected, but via organic fermentation products. O2 supply by the tides was not sufficient and reduced intermediates escaped from the sediment with tidal water retraction. The resulting extremely high levels of free sulfide (〉10 mmol L-1) lead to abundant filamentous growth of sulfur-oxidizing bacteria largely composed of a rare O2-adapted Sulfurovum lacking the expected denitrification genes. Our results show that regular kelp deposition strongly enhances the thermodynamic disequilibrium in the beach sand habitat, leading to a dramatic enhancement of the sulfur cycle.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 10
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    The Guaymas Basin hiking guide to hydrothermal mounds, chimneys, and microbial mats : complex seafloor expressions of subsurface hydrothermal circulation (2016)
    Frontiers Media
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 7 (2016): 75, doi:10.3389/fmicb.2016.00075.
    Description: The hydrothermal mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface hydrothermal circulation patterns. In this overview, we document the most frequently visited features of this hydrothermal area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and hydrothermal sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these hydrothermal features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region.
    Description: AT acknowledges a W. Reynolds research leave from UNC, Guaymas-relevant support from the Center for Dark Energy Biosphere Investigations (C-DEBI) at the University of Southern California
    Keywords: Guaymas basin ; Hydrothermal circulation ; Hydrothermal sediment ; Beggiatoa mat ; In situ profiles ; Heatflow ; Porewater chemistry
    Repository Name: Woods Hole Open Access Server
    Type: Article
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