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Found 7 results.

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Pressure-induced leakage of dissolved organic matter (DOM) from diatom-bacteria aggregates

Model diatom aggregates were produced from the diatom Skeletonema marinoi and the natural microbial community of seawater collected in Oeresund (Stief et al. 2023), Central Arctic Ocean, and Japan Trench. S. marinoi was grown to stationary phase in L1 medium plus silicate (Guillard & Hargraves 1993) at 15°C under a light/dark regime of 14/10 h. The diatom aggregates were individually incubated at either atmospheric pressure (0.1 MPa = control treatment) or at gradually increasing hydrostatic pressure (0.1-100 MPa = pressure treatment) throughout 20 days in darkness and at 3°C. The pressure treatment simulated the sinking of diatom-bacteria aggregates from the ocean surface down into a hadal trench of 10 km depth. Pressure-induced leakage of dissolved organic matter (DOM) was followed throughout the incubations. Ambient concentrations of different DOM components were measured: Dissolved organic carbon (DOC), total dissolved nitrogen (TDN), protein-like and humic-like DOM fluorescence.

Extracellular dissolved organic carbon (DOC) concentrations in axenic and xenic cultures of Thalassiosira gravida in response to varying temperatures and photoperiods

This dataset comprises dissolved organic carbon (DOC) concentrations from axenic and xenic cultures of Thalassiosira gravida that were cultivated at the Alfred-Wegener-Institute (Bremerhaven, Germany) in March, 2023. After a cell density of ~ 15.000 cells * mL-1 was reached, cultures were filtered through a 0.2 µm polycarbonate (PC) filter (Whatman) that was cleaned by soaking in 10 % hydrochloric acid (HCl, Merck suprapure) for at least 12 h and subsequently rinsing with ultrapure water (Merck Millipore MilliQ). DOC was quantified by high temperature catalytic oxidation with a Shimadzu TOC analyzer (VCPN-TOC, Shimadzu) according to Garzón-Cardona et al. 2024; doi: 10.1016/J.JMARSYS.2023.103893. Cultures were grown under two temperatures (9 °C, 13.5 °C) and two photoperiods (16:8 h, 24:0 h light:dark). The aim was to investigate responses of algal extracellular release and bacterial DOC transformation to marine heatwave-like conditions.

Dissolved organic matter (DOM) composition in axenic and xenic cultures of Thalassiosira gravida in response to varying temperatures and photoperiods

This dataset comprises dissolved organic matter (DOM) composition from axenic and xenic cultures of Thalassiosira gravida that were cultivated at the Alfred-Wegener-Institute (Bremerhaven, Germany) in March, 2023. After a cell density of ~ 15.000 cells * mL-1 was reached, cultures were filtered through a 0.2 µm polycarbonate (PC) filter (Whatman) that was cleaned by soaking in 10 % hydrochloric acid (HCl, Merck suprapure) for at least 12 h and subsequently rinsing with ultrapure water (Merck Millipore MilliQ). Cultures were grown under two temperatures (9 °C, 13.5 °C) and two photoperiods (16:8 h, 24:0 h light:dark). 2 mL of the sample were filtered through a 0.2 µm regenerated cellulose (RC)-membrane syringe filter (Sartorius) after defrosting. Molecular composition data were acquired with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) coupled to a reversed-phase liquid chromatography (RPLC) with negative electrospray ionization (ESI) according to Lechtenfeld et al., 2024 (doi: 10.1021/acs.est.3c07219). Measurements were performed on on a solariX XR, Bruker Daltonics, Billerica, U.S.A. at the Helmholtz Centre for Environmental Research (UFZ; Leipzig, Germany). Molecular formulas were assigned and filtered using UltraMassExplorer (Leefmann et., 2019; doi: 10.1002/rcm.8315). If the Total ion chromatogram (TIC) was much higher and/or different in certain retention time windows compared to other samples of the same treatment, the sample was excluded from the dataset. The aim of this study was to investigate responses of algal extracellular release and bacterial DOM transformation to marine heatwave-like conditions.

CH4 concentrations in the culture system during long-term culture of Gigantidas childressi

The seawater in the G. childressi culture system was enriched with methane by injection of methane-enriched air from an air-methane gas mixing device. methane concentrations were monitored using a CONTROS HydroC® CH₄ sensor in the filter tank of the culture system.

Degradation of diatom-derived dissolved organic matter (DOM) in surface seawater

Stored surface seawater originally collected in the North Sea was amended with dissolved organic matter (DOM) obtained from the diatom Skeletonema marinoi by exposing the diatom culture to a hydrostatic pressure level of 40 MPa for 24 h. To this end, S. marinoi had been grown to stationary phase in L1 medium plus silicate (Guillard & Hargraves 1993) at 15°C under a light/dark regime of 14/10 h. Diatom-cell-free DOM was added to aliquoted seawater samples at initial concentrations of 250 µmol C/L. The microbial degradation of the added DOM and the microbial response to DOM-amendment at 15°C and in darkness was followed for 2 weeks. The seawater was subsampled at defined time intervals to analyze a number of variables.

Methane concentrations in deep-sea mussel culture: continuous methane feeding

During culture of deep-sea mussels Gigantidas Childressi in September 2017, the culture system (200 L) was continuous enriched with methane by bubbling with methane-enriched air (4% methane). The CH4 concentrations were measured by CONTROS HydroC® CH₄ sensor placed in the culture system.

Methane concentrations in deep-sea mussel culture: hand feed

During culture of deep-sea mussels Bathymodiolus azoricus in November 2013, the culture system (200 L) was repetitively enriched with methane by adding 5 L CH4-saturated sea water (after 15 minutes of equilibration with a gas diffusor stone, solution containing ~8 mmol of CH4). The CH4 concentrations were continuously measured by CONTROS HydroC® CH₄ sensor placed in the culture system.

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