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Chlorophyll a, extracellular polymeric substance concentration and 16S rRNA gene copy numbers in saltmarsh sediments in response to a storm surge

Samples were taken to study the effect of storm surges on ecosystem functioning of salt marsh microbial communities. Sediment samples were collected from experimental salt marsh islands located in the back-barrier tidal flats of Spiekeroog Island, German North Sea (53°45′N, 7°43′E). The islands consist of three elevation zones (0.7 m, 1.0 m, and 1.3 m above mean sea level), corresponding to pioneer zone, lower salt marsh, and upper salt marsh. Six islands were sampled (three initially bare; three transplanted with lower salt marsh sediment and vegetation). Sampling was conducted in September 2022 (pre-disturbance), March 2023 (post-winter storm surges), and August 2023 (recovery phase). Surface sediments (upper 2 cm) were collected using syringe cores. Pooled samples were analyzed for chlorophyll a as a proxy for microphytobenthos biomass using ethanol extraction and spectrophotometric pigment analysis. Extracellular polymeric substances (EPS) were quantified using EDTA extraction followed by phenol–sulfuric acid carbohydrate analysis. DNA was extracted from sediment subsamples using a Qiagen PowerSoil kit. Prokaryotic abundance was estimated by quantitative PCR targeting the 16S rRNA gene (primers 519F/907R), using an Escherichia coli 16S rRNA gene standard curve. The dataset includes chlorophyll a concentrations (µg g⁻¹ dry sediment), EPS carbohydrate concentrations, and prokaryotic 16S rRNA gene copy numbers for all sampling times, elevations, and treatments.

KOSMOS 2023 Helgoland mesocosm study on ocean alkalinity enhancement: sediment trap particle flux data and water column biogeochemistry

The data presented herein originates from a mesocosm study conducted as part of the BMBF CDRmare, Retake project (grant agreement no. 03F0895A), aimed at investigating the ecological ramifications of ocean alkalinity enhancement (OAE). Twelve mesocosms were deployed in Helgoland South Harbor, Germany, and systematically sampled using integrated water samplers over the period spanning from March 12th to April 20th, 2023. Six alkalinity levels under two dilution scenarios were established to differentiate between localized and uniform OAE additions. Alkalinity was increased stepwise to ΔTAmax = 1250 μmol kg-1 (250 μmol TA kg-1 increments) using sodium hydroxide (NaOH) with calcium chloride (CaCl2) to simulate cation release during calcium-based mineral dissolution, causing strong carbonate chemistry perturbations (e.g., pHT > 9.25). The dataset encompasses a spectrum of sediment trap particle flux data, water column biogeochemistry including pigment variables, inorganic nutrients, carbonate chemistry parameters. The study and data set offer insights into impacts of alkalinity enhancement on marine ecosystems and their associated biogeochemistry.

Kreislauffähige, upgecycelte Pigmente für alle 'Next Generation' (Next-Gen) Materialien, Teilprojekt: Entwicklung von kreislauffähigen Materialprototypen aus NUVIs Biomaterialien unter Einbindung von hochwertigen Grund- und Farbstoffen aus Agrar- und Baumwollabfällen

X-ray fluorescense (XRF) core scanning from sediment core HZM19, Holzmaar (West-Eifel Volcanic Field, Germany)

XRF measurements in 0.2 to 1 mm increments with an ITRAX XRF core scanner (Cox Analytics) and Cr tube (Croudance et al. 2015, doi:10.1007/978-94-017-9849-5 ). The sediment core HZM19 was collected in 2019, from Holzmaar, West-Eifel Volcanic Field in Germany using a UWITEC Piston Corer. The sediment core was collected to reconstruct environmental and climate changes of Holzmaar for the last 16,000 years cal BP. Particularly in this data set we cover between 2450-2950 cal BP.

Biogeochemical variables from a Multidisciplinary BASS Mesocosm Study at Wilhelmshaven, 2023

This dataset contains biogeochemical variables measured during the same mesocosm experiment at Sea Surface Facility (SURF) in Wilhelmshaven, Germany (53.5148° N, 8.1461° E) in 2023. Variables include surfactants and nutrient concentrations, chlorophyll a, pigments, particulate and dissolved organic carbon and nitrogen, and several other biogeochemical parameters. These data complement the daily averaged physical parameters (PANGAEA DOI: https://doi.pangaea.de/10.1594/PANGAEA.983975) and together support the assessment of ecosystem and biogeochemical dynamics associated with the experiment, as described in the related publication Bibi et al., 2025.

A validation data set of phytoplankton pigment concentrations and phytoplankton groups measured on water samples collected from various expeditions

This data set composes quality controlled in situ measurements of eight major pigments based on HPLC collected from various expeditions from 2016 to 2023. There are two subsets: subset 1 is the test dataset (99 matchups) extracted from and takes up 30 % of a global in situ PFT matchup data set, while the other 70 % was used for the retuning of the PFT algorithm for Sentinel 3 OLCI sensors. Subset 1 spans from 2016 to 2021 and is part of the global data set described in Xi et al. (2023): https://doi.pangaea.de/10.1594/PANGAEA.954738. Subset 2 containing 134 matchups is a newly compiled dataset that composites in situ PFT data collected from four recent mostly polar expeditions with the research vessel Polarstern (Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 2017), that are PS126 (May–June 2021), PS131/1 (June–Aug 2022) and PS136 (May–June 2023) in the north Atlantic to the Arctic Ocean, and PS133 (Oct–Nov 2022) in the Southern Ocean. The in situ PFT data were derived from quality-controlled HPLC pigment concentrations using diagnostic pigment analysis (DPA) with updated pigment-specific weighting coefficients following Xi et al. (2023). This published data set has been used to validate satellite PFT products generated for the EU funded Copernicus Marine Service (CMEMS, https://marine.copernicus.eu/), which are derived from multi-sensor ocean color reflectance data and sea surface temperature using an empirical orthogonal function based approach (Xi et al. 2020; 2021).

Phytoplankton pigment concentrations during POLARSTERN cruise PS121 from North Sea to Fram in August to September 2019

Phytoplankton pigments were determined in the water column of a transect from the North Sea to Fram Strait during RV Polarstern expedition PS121 from 11 Aug to 10 Sep 2019. Water samples were collected from CTD Niskin bottles at five to six different depths from the upper 100 m at CTD stations and from underway sampling. This were the same water samples as in Bracher et al. (https://doi.pangaea.de/10.1594/PANGAEA.938260). Between 0.2 to 3.5 L of each seawater sample was filtered through Whatman GF/Ffilters. The sample filters were then shock‐frozen in liquid N2 and kept at−80 °C until analysis. High Pressure Liquid Chromatography (HPLC) was performed to quantify various phytoplankton pigments (see Table 1 in Taylor et al. 2011) following the method of Barlow et al. (1997) that was adjusted to our temperature‐controlled instruments as detailed in Alvarez et al. (2022).

Total and phytoplankton group chlorophyll concentrations from underway spectrophotometry with water mass classification in the East Greenland Sea from Polarstern expeditions 2015-2024

We present a high spatially resolved (around 300 m) data set on the chlorophyll-a concentrations of all phytoplankton (total chlorophyll-a), diatoms, haptophytes and chlorophytes various phytoplankton pigments (unit: mg/m³) estimated from particulate absorption data derived from underway AC-S measurements operated on eight R/V POLARSTERN expeditions in the Greenland Sea (North of 66.3°N to 82°N within the Atlantic Ocean) between 2015 to 2024: PS93.2, PS99.2, PS107, PS121, PS126, PS131, PS136 and PS143-2. For each data point we further provide the percentage of Atlantic Water and Polar Water and the association into the three regions: East Greenland Sea, Central Fram Strait and West Spitsbergen Current. Mind that the classification of water masses and regions is only valid for the Hausgarten area (78°N to 80°N and 7°W to 15°E). The details of the instrument set-up, the data and the methods are described in Bracher et al. (2025).

Phytoplankton pigment and phytoplankton group chlorophyll-a concentrations during POLARSTERN cruise PS126 from North Sea to Fram Strait in May to June 2021 from HPLC analysis of water samples

Phytoplankton pigments were determined in the water surface (from 0 to 11 m depth) of a transect from the North Sea to Fram Strait and back during RV Polarstern expedition PS126 from 24 May to 25 June 2021. Water samples were collected from CTD Niskin bottles at five to six different depths from the upper 100 m at CTD stations and from underway sampling. Between 0.4 to 3.5 L of each seawater sample was filtered through Whatman GF/F filters. The sample filters were then shock‐frozen in liquid N2 and kept at−80 °C until analysis. High Pressure Liquid Chromatography (HPLC) was performed to quantify various phytoplankton pigments (see Table 1 in Taylor et al. 2011) following the method of Barlow et al. (1997) that was adjusted to our temperature‐controlled instruments as detailed in Alvarez et al. (2022).

Physical, chemical, and biogeochemical parameters from a mesocosm experiment at the Sea Surface Facility (SURF), Wilhelmshaven, Germany, spring 2023

This collection (bundled publication) includes datasets from a mesocosm experiment conducted in spring 2023 at the Sea Surface Facility (SURF), Wilhelmshaven, Germany (53.5148° N, 8.1461° E). The experiment initiated a phytoplankton bloom under controlled conditions to examine surface ocean biogeochemistry and sea-surface microlayer (SML) processes. Daily samples were collected from the SML and underlying water (40 cm depth) and analyzed for physical, chemical, and biological parameters. Measurements include meteorological conditions (air temperature, solar irradiance, and albedo), surfactants, nutrients, pigments, particulate and dissolved organic carbon and nitrogen, and additional biogeochemical variables. These datasets provide environmental and biogeochemical context supporting studies on surface ocean processes and are described in detail in the related publication Bibi et al. (2025).

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