This dataset was collected during the cruise MSM129/1 with RV MARIA S. MERIAN from Warnemünde, Germany to St. John's, Canada. It contains suspended particulate matter, particulate organic matter and particulate inorganic matter measurements [mg/l] from water samples collected from the seawater supply (Reinseewassersystem, RSWS) to calibrate the turbidity data of the RSWS system. The outflow of a PocketFerrybox that was connected to the seawater supply in the hangar was used for sampling. It takes a substantial amount of time for the water to reach the hanger from the intake point. The time delay between the sensor readings of the RSWS and the PocketFerrybox was determined and the timestamps of the water sampling were adjusted accordingly. Given latitute and longitude refer to this corrected timestamp. The original time of water sampling in the hangar is given as an additional column with the comment time of sampling. To obtain suspended particulate matter concentrations, water samples were filtered onboard through 0.7 μm pore size, glass fiber filters (Whatmann GF/F, 47 mm) under low vacuum. Filters were frozen immediately at -80 °C until gravimetric analysis in the laboratory at ICBM, Wilhelmshaven according to IOCCG recommendations.
Data presented here were collected between 2019-09 and 2023-09 at station BEFmate_S4low within the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems, https://uol.de/dynacom/ ) involving the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Experimental islands and saltmarsh enclosed plots were established in the back-barrier tidal flat and in the saltmarsh zone of the island of Spiekeroog (Germany). Salinity at different elevation zones was measured using conductivity loggers deployed in dip wells within experimental islands as well as in the saltmarsh enclosed plots. Measurements were obtained using HOBO U24 Conductivity Logger U24-002-C (Onset Computer Corporation, Bourne, MA/USA). All devices were pre-calibrated by the manufacturer. Logged data were retrieved in the field using a Hobo Underwater Shuttle (U-DTW-1) and were read out with the HOBOware Pro (V3.7.28) software. Salinity was derived in HOBOware Pro using temperature-dependent, nonlinear seawater conductivity compensation following the Practical Salinity Scale (PSS-78). Subsequent data processing was done using MATLAB (R2024b). Post-processing and quality control included (a) the removal of data covering maintenance activities, (b) the removal of implausible values using fixe thresholds (salinity > 40 psu and < 5 psu; temperature > 35 °C and < -5 °C), c) an outlier detection using the Hampel filter method, and (d) visual checks. Identified outliers were removed and synchronously removed across all associated parameters (temperature and salinity).
We studied dissolved organic matter (DOM) dynamics in the sea surface microlayer (SML) during a mesocosm study at the Sea sURface Facility (SURF) of the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany (53.5148 °N, 8.1463 °E). The study was conducted from 18 May to 16 June 2023 as part of the multidisciplinary BASS research unit (Biogeochemical processes and Air-sea exchange in the Sea-Surface microlayer). SURF was filled with pretreated natural seawater from the nearby Jade Bay (53° 28' 42'' N, 8° 12' 15'' E) to replicate natural conditions. We selected this approach to examine the regrowth of surviving phytoplankton cells after the initial water treatments, simulating a native microbial community starting with almost no bioproduction or pre-existing bioproduction products. To induce and maintain the phytoplankton bloom, inorganic nitrogen, phosphorus, and silicate were added on May 26, May 31, and June 01, 2023. By that, we induced an algal bloom of Emiliania huxleyi and Cylindrotheca closterium. Water samples were collected using a glass plate for the SML and a tube at 40 cm depth for the underlying water (ULW). This dataset contains DOM molecular data from ultrahigh-resolution mass spectrometry (Fourier-transform ion cyclotron resonance mass spectrometer, FT-ICR-MS), molecular indices calculated from FT-ICR-MS data (Ibio, Iphoto, IDEG) and environmental data, including dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). Furthermore, it contains attenuated total reflectance Fourier Transform Infrared (ATR-FTIR) data from representative samples for each bloom phase. By combining molecular analyses with nutrient and bloom-phase data, we highlight the in situ production of carbohydrate-like and laminarin-derived DOM as a significant contributor to SML composition. General metadata from the multidisciplinary mesocosm study, including temperature, salinity and chlorophyll a, are provided in Bibi et al. on PANGAEA at the following link: doi:10.1594/PANGAEA.984101.
Data presented here were collected between 2019-09 and 2021-07 at station BEFmate_S3upp within the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems, https://uol.de/dynacom/ ) involving the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Experimental islands and saltmarsh enclosed plots were established in the back-barrier tidal flat and in the saltmarsh zone of the island of Spiekeroog (Germany). Salinity at different elevation zones was measured using conductivity loggers deployed in dip wells within experimental islands as well as in the saltmarsh enclosed plots. Measurements were obtained using HOBO U24 Conductivity Logger U24-002-C (Onset Computer Corporation, Bourne, MA/USA). All devices were pre-calibrated by the manufacturer. Logged data were retrieved in the field using a Hobo Underwater Shuttle (U-DTW-1) and were read out with the HOBOware Pro (V3.7.28) software. Salinity was derived in HOBOware Pro using temperature-dependent, nonlinear seawater conductivity compensation following the Practical Salinity Scale (PSS-78). Subsequent data processing was done using MATLAB (R2024b). Post-processing and quality control included (a) the removal of data covering maintenance activities, (b) the removal of implausible values using fixe thresholds (salinity > 40 psu and < 5 psu; temperature > 35 °C and < -5 °C), c) an outlier detection using the Hampel filter method, and (d) visual checks. Identified outliers were removed and synchronously removed across all associated parameters (temperature and salinity).
Grundwasserversalzungen beeinträchtigen in weiten Bereichen der schleswig-holsteinischen Westküste die Beschaffenheit der oberflächennahen Wasserleiter. Ursächlich hierfür sind natürliche Prozesse, insbesondere das landwärtige Eindringen von Meerwasser sowie das Aufsteigen salziger Tiefenwässer infolge hydraulischer Druckentlastung. Die Karte zeigt die überwiegend versalzenen Bereiche (rot) und die überwiegend nicht versalzenen Bereiche (blau) in den Marschen und Niederungen der Westküste.
Culturing experiments were performed with the benthic foraminifer Ammonia aomoriensis from Flensburg Fjord, western Baltic Sea. The experiments simulated a projected rise in atmospheric CO2 concentrations. We exposed specimens to 5 seawater pCO2 levels ranging from 618 µatm (pH 7.9) to 3130 µatm (pH 7.2) for 6 wk. Growth rates and mortality differed significantly among pCO2 treatments. The highest increase of mean test diameter (19%) was observed at 618 µatm. At partial pressures >1829 µatm, the mean test diameter was observed to decrease, by up to 22% at 3130 µatm. At pCO2 levels of 618 and 751 µatm, A. aomoriensis tests were found intact after the experiment. The outer chambers of specimens incubated at 929 and 1829 µatm were severely damaged by corrosion. Visual inspection of specimens incubated at 3130 µatm revealed wall dissolution of all outer chambers, only their inner organic lining stayed intact. Our results demonstrate that pCO2 values of >=929 µatm in Baltic Sea waters cause reduced growth of A. aomoriensis and lead to shell dissolution. The bottom waters in Flensburg Fjord and adjacent areas regularly experience pCO2 levels in this range during summer and fall. Increasing atmospheric CO2 concentrations are likely to extend and intensify these periods of undersaturation. This may eventually slow down calcification in A. aomoriensis to the extent that net carbonate precipitation terminates. The possible disappearance of this species from the Baltic Sea and other areas prone to seasonal undersaturation would likely cause significant shifts in shallow-water benthic ecosystems in the near future.
About 30% of the anthropogenically released CO2 is taken up by the oceans; such uptake causes surface ocean pH to decrease and is commonly referred to as ocean acidification (OA). Foraminifera are one of the most abundant groups of marine calcifiers, estimated to precipitate ca. 50 % of biogenic calcium carbonate in the open oceans. We have compiled the state of the art literature on OA effects on foraminifera, because the majority of OA research on this group was published within the last three years. Disparate responses of this important group of marine calcifiers to OA were reported, highlighting the importance of a process-based understanding of OA effects on foraminifera. We cultured the benthic foraminifer Ammonia sp. under a range of carbonate chemistry manipulation treatments to identify the parameter of the carbonate system causing the observed effects. This parameter identification is the first step towards a process-based understanding. We argue that CO3 is the parameter affecting foraminiferal size-normalized weights (SNWs) and growth rates. Based on the presented data, we can confirm the strong potential of Ammonia sp. foraminiferal SNW as a CO3 proxy.
Seed-based restoration is a promising approach to accelerate the slow natural recolonization of Zostera marina meadows. In this study, seed-based restoration was investigated through the injection of seeds into the sediment using syringes. Parallel laboratory and field experiments were conducted to examine the germination success over time under both simulated and natural field conditions. A laboratory experiment was conducted in the climate chambers of GEOMAR Helmholtz Centre for Ocean Research Kiel. Twelve replicate aquaria, each containing 6 boxes of 18 cm*13 cm*18 cm, were set up in a climate chamber. Each plastic box in the aquaria was filled with 6 cm of sandy sediment collected from sandbanks next to seagrass meadows in Falckenstein near Kiel (54°23'39.4N 10°11'23.6E). For sterilization, the sediment was autoclaved at 121°C for 20 minutes before use. Water was changed weekly, with approximately 30% replaced by filtered (50 μm and 5 μm filter cascade) Baltic Sea water with an ambient salinity ranging from 14-16 PSU. The chamber simulated field conditions typical for the season, with 12 hours of light per day and a temperature of 10°C. In each box, a seed amount equivalent to the weight of 100 Zostera marina seeds was sown, based on the average seed weight determined prior to the experiment. Seeds were collected at two sites in Laboe and Falckenstein (Kiel Fjord) in July 2023 by snorkelers and scientific divers (Laboe: 54° 24' 48.53 N, 10° 13' 29.91 E; Falckenstein: 54° 23' 31.36 N, 10° 11' 31.15 E). They were overwintered in climate cabinets in darkness at 4°C and a salinity of 32 PSU, where they rotated every 6 hours for 1 minute. Different treatment combinations were tested, involving the factors Sowing Method (syringe (100 ml) with agar medium or Hand-Sown), Sowing Depth (2 cm or 4 cm), Origin of Seeds (Falckenstein or Laboe), and Fertilization of the Sediment (from the beginning, after germination, or none at all). The Hand-Sown method served as a control. To this end, the box was filled with about 4cm autoclaved sandy sediment. Then the seeds were evenly distributed on the surface and covered with either 2 cm or 4 cm of sediment before being gently lowered into the aquarium. For the syringe treatment, seeds were injected into the sediment embedded in an agar medium prepared by cooking Baltic Sea water with 1.8% agar (Agar-Agar, BioScience Grade, pulv., Carl Roth). Each syringe contained 90 ml crumbly agar, 10 g autoclaved sediment, 100 seeds and depending on the treatment, either 1g charcoal powder, nutrients (P and N) or no further additions. For the nutrients, according to the Redfield ratio N:P = 16:1, 100 μL of nitrogen and 10 μL of phosphorus were used per 90 mL of agar. There were three timing treatments for "Timing of Nutrients in the Sediment". "Nutrients from Beginning", "Nutrients after Germination" and "no Nutrients". The treatment was the same for all boxes within one aquarium to avoid potential influence on the surrounding water. As fertilizer "osmocote Langzeitdünger 6 Monate" (N P 19+9) was used. In the boxes with "Nutrients from Beginning", two pellets were inserted with tweezers into the sediment directly after sowing. In the boxes with "Nutrients after Germination", the same treatment started on April 29, 2024, after many of the seedlings had already developed some green leaves. The seeds were sown on March 4, 2024, and from March 21 to May 25, 2024, emerging seedlings were counted three times per week. Seedlings with only cotyledons and seedlings with developed green leaves were counted together in the beginning and separately from April 24, 2024, onwards.
In Folge des globalen Klimawandels hat sich die Meereisdecke in der Arktis dramatisch verändert. Im derzeitigen Zustand spielt die arktische Eisdecke eine wichtige Rolle; so schirmt sie das Oberflächenwasser, die sogenannte arktische Halokline (Salzgehaltsschichtung), von der Erwärmung durch die sommerliche Sonneneinstrahlung ab. Zudem wird die Halokline durch die Salze, welches beim Gefrierprozess des Meerwassers aus der Kristallstruktur austritt, gebildet und stabilisiert. Gleichzeitig wirkt die Halokline als Barriere zwischen der Eisdecke und dem darunter liegenden warmen atlantischen Wasser und trägt so zum Erhalt der arktischen Meereisdecke bei. Dieses Gleichgewicht ist nun durch die insgesamt wesentlich dünnere arktische Meereisdecke und ihre verringerte sommerliche Ausdehnung gestört. Im Meerwasser sind zudem Gase und biogeochemisch wichtige Spurenstoffen enthalten. Diese werden durch die Gefrierprozesse eingeschlossen, beeinflusst und wieder ausgestoßen. So beeinflusst die Meereisdecke die Gas- und Stoffflüsse zwischen Atmosphäre, Eis und oberer Wasserschicht. Durch die Eisbewegung findet außerdem ein Transport statt z.B. in der sogenannten Transpolarendrift von den sibirischen Schelfgebieten, über den Nordpol, südwärts bis ins europäische Nordmeer. Nun wird mit den weitreichenden Veränderungen des globalen und arktischen Klimawandels bereits von der „neuen Arktis“ gesprochen, da angenommen wird, dass sich die Arktis bereits in einem neuen Funktionsmodus befindet. Dabei ist jedoch weitgehend unbekannt wie dieses neue System funktioniert, sich weiterentwickelt und wie sich dies auf die Eisbildungsprozesse und damit die Stabilität der Halokline und die damit verbundenen Gas- und Stoffflüsse auswirkt. Für solche Untersuchungen werden über den Jahresverlauf Proben der oberen Wassersäule und der Eisdecke benötigt. Ermöglicht wird dies durch die wissenschaftliche Initiative MOSAiC. Mithilfe der stabilen Isotope des Wassers (?18O und ?D) aus dem Eis und der Wassersäule kann Rückschlüsse auf die Herkunftswässer und den Gefrierprozess gezogen werden und diese Ergebnisse sollen in direkten Zusammenhang mit Gas- und biogeochemischen Stoffuntersuchungen (aus Partnerprojekten) gesetzt werden. Dabei können z.B. Stürme, Schmelzprozesse, Schneebedeckung, Teichbildung und Alterungseffekte des Eises eine Rolle spielen. Untersucht wird parallel die Veränderung der Wassersäule welche z.B. durch Wärmetransport, wiederum die Eisdecke beeinflussen kann.Diese prozessorientierten Untersuchungen der saisonalen Eisbildungsprozesse in Eis und Wassersäule der zentralen Arktis, werden einen wichtigen Beitrag zum Verständnis der Stabilität der arktischen Halokline und der arktischen Gas- und Stoffflüsse liefern. Da sich die Gase und Stoffe nicht-konservativ verhalten, während die Isotope im Gefrierprozess konservativ sind, erwarten wir aus der Diskrepanz wiederum wichtige Informationen z. B. über wiederholtes Einfrieren von Süßwasserbeimengungen ableiten zu können.
Data presented here were collected between November 2019 to September 2023 within the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems, https://uol.de/dynacom/ ) involving the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Experimental islands and saltmarsh enclosed plots were established in the back-barrier tidal flat and in the saltmarsh zone of the island of Spiekeroog (Germany). A recording current meter (RCM; SEAGUARD® Recording Current Meter, Aanderaa Data Instruments AS, Bergen/Norway) was installed in the back-barrier tidal flat near the experimental islands. The sensor was bottom-mounted in a shallow tidal creek (0.59 m NHN) using a steel girder buried in the sediment, which caused the sensor to be exposed during low tide. All low-tide data have been removed from the dataset. The system was equipped with a ZPulse Doppler Current Sensor (DCS), a conductivity sensor, an oxygen optode, and two analogue sensors for chlorophyll-a and turbidity (16445). All sensors were pre-calibrated by the manufacturer. Recorded data were internally logged until readout with the SeaGuard Studio software (V1.5.23). Salinity was derived in the SeaGuard Studio software using temperature-dependent, nonlinear seawater conductivity compensation following the Practical Salinity Scale (PSS-78). Subsequent data processing was done using MATLAB (R2024b). Turbidity and chlorophyll-a data were excluded from the final dataset, as the recorded signals show implausible values and did not pass quality-control criteria. Post-processing and quality control included (a) the removal of low tide data, data covering maintenance activities, and data affected by biofouling, (b) the removal of implausible values, c) an outlier detection using the Hampel filter method, and (d) visual checks. Identified outlier were removed and synchronously removed across all associated parameters of the respective sensor.
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