ALBERT

Description: The discrete biogeochemical measurements from RV Maria S. Merian MSM77 sampled for organic matter, primary production and phytoplankton abundances. The parameters include POC, phytoplankton abundances and production. The samples were acquired within 0-100 m of the Greenland Sea between 78°N to 80°N and 3°E to 10°E. The data was collected daily on board MSM77 from 16th September 2018-4th October 2018. The water collection occurred using a CTD and laboratory methods varied by parameter. POC was analyzed using a EURO EA CHNS-O Elemental Analyzer, carbohydrates were analyzed using High performance anion exchange chromatography with pulsed amperometric detection, amino acids were analyzed using High Performance Liquid Chromatography (HPLC) ortho-phthaldialdehyde derivatization, rates of primary production (PP) were measured in situ using the 14C method and subsampled as total PP (PP-TOC), particulate PP (PP-POC), and dissolved PP (PP-DOC), cell abundances were measured using orange and red autofluorescence detected by flow cytometry. The purpose of data collection was to understand seasonal cycling of organic mater.

Description: The discrete biogeochemical measurements from RV Polarstern PS114 sampled for organic matter, primary production and phytoplankton abundances. The parameters include POC, phytoplankton abundances and production. The samples were acquired within 0-100 m of the Greenland Sea between 78°N to 80°N and 3°E to 10°E. The data was collected daily on board PS114 from 16th July 2018-23rd July 2018 . The water collection occurred using a CTD and laboratory methods varied by parameter. POC was analyzed using a EURO EA CHNS-O Elemental Analyzer, carbohydrates were analyzed using High performance anion exchange chromatography with pulsed amperometric detection, amino acids were analyzed using High Performance Liquid Chromatography (HPLC) ortho-phthaldialdehyde derivatization, rates of primary production (PP) were measured in situ using the 14C method and subsampled as total PP (PP-TOC), particulate PP (PP-POC), and dissolved PP (PP-DOC), cell abundances were measured using orange and red autofluorescence detected by flow cytometry. The purpose of data collection was to understand seasonal cycling of organic mater.

Description: The discrete biogeochemical measurements from RV Polarstern PS114 and RV Maria S. Merian MSM77 sampled for dissolved organic matter, heterotrophic bacteria and gel particles. The parameters include chlorophyll, DOC/TDN/TDP/DOP, dissolved hydrolysable amino acids, dissolved combined carbohydrates, heterotrophic bacterial abundance and production, gel particles like TEP and CSP. The samples were aquired within 0-100 m of the Greenland Sea between 78°N to 80°N and 2°W to 14°E. The data was collected daily on board PS114 from 16th July 2018-23rd July 2018 and on board MSM77 from 16th September 2018-4th October 2018. The water collection occured using a CTD and laboratory methods varied by parameter. Chlorophyll was extracted using acetone, DOC/TDN was analysed using High-Temperature Catalytic Oxidation (TOC-VCSH), TDP/DOP was analysed colorimetrically using Acidic Molybdate Solution, dissolved hydrolysable amino acids were analysed using High Performal Liquid Chromatography (HPLC) Ortho-phthaldialdehyde Derivatization, dissolved combined carbohydrates were analysed using High Performance Anion Exchange Chromatography (HPAEC) coupled with Pulsed Amperometric Detection (PAD), cell abundance was analysed using flow cytometery, bacterial production was analysed using radioactively labelled 3H-Leucine and apllication of the microcentrifuge method, gel particles were analysed microscopically followed by image analysis. The purpose of data collection was to understand seasonal cycling of organic mater and heterotrophic bacteria dynamics within microbial loop.

Description: The discrete biogeochemical measurements from RV Akademik Tryoshnikov AT21 sampled for chlorophylla, delta 18O isotopes, dissolved organic matter and microbial cell abundances. The parameters include dO, d18O, Chla, DOC, cDOM, TDN, DIN, combined carbohydrates, hydrolysable amino acids, and microbial cell abundances. The samples were aquired within 0-10 m of the Barents and Laptev Sea, lake, and snow between 76 N to 82 N and 59 E to 106 E. The data was collected on board Arctic Century cruise from 09th August 2021-2nd September 2021. The water collection occured using a CTD, bucket (lake) and gloves (snow, thawed). The laboratory methods varied by parameter: chlorophyll using Turner Designs Trilogy fluorometer, oxygen isotopes using a Finnigan Delta-S mass spectrometer, DOC/TDN was analysed using TOC-VCSH, and cDOM were analyzed spectrophotometrically, dissolved carbohydrates using high performance anion exchange chromatography coupled with pulsed amperometric detection, dissolved amino acids using ortho-phthaldialdehyde derivatization by high-performance liquid chromatography, and microbial cell abundance (phytoplankton, bacteria) was analysed using flow cytometery. The purpose of data collection was to understand spatial variability of organic mater and associated dynamics of the microbial loop.

Description: We performed a temperature incubation experiment on board the RV Polarstern with a unicellular microbial community sampled from the Hausgarten station IV in Fram Strait during the campagin PS126 on June 1st, 2021 (Soltwedel et al., 2021). The community was sampled with CTD-bound niskin bottles (SBE 32 Carousel Water Sampler attached to a Seabird SBE911+ CTD-system; Seabird Scientific, Bellevue, WA, USA) from a depth of 15 m (Hoppmann et al., in review) and, after filtering the seawater through a 150 µm net, incubated in triplicate on plankton wheels in three temperature-controlled containers for ten days. To mimick todays and potential future temperature conditions of the Arctic ocean, we chose a control temperature of 2 °C, an intermediate warming scenario of 6 °C, and an extreme warming scenario of 9 °C. The goal was to investigate the effects of concurrent warming and Atlantification and therefore we chose an Arctic-Atlantic mixed water mass as community origin. This dataset comprises the chlorophyll, particulate nutrients, dissolved nutrients, carbonate chemistry, and flow cytometric measurements of the starting as well as the final communities. A total 300 mL of sample water for chlorophyll a, and 200 mL for particulate organic carbon and nitrogen (and the same volumes of ultrapure water for blank corrections), were vacuum-filtered (〈−200 mbar) onto pre-combusted glass-fiber filters (GF/F Whatman, Maidstone, UK). These were put into 2 mL cryovials (Sarstedt, Nümbrecht, Germany) and kept at −80 °C until processing. Filters for chlorophyll a were manually shredded in 6 mL of 90% acetone and extracted for 20 h at 8 °C according to the EPA method 445.0 (Arar et al., 1997). The extract was centrifuged to remove residual filter snips, and Chlorophyll a was determined on a Trilogy fluorometer (Turner Designs, San Jose, CA, USA) after correcting for phaeopigments via acidification (1 M HCl). Filters for particulate nutrients were also acidified (0.5 M HCl) and dried for 12 h at 60 °C. Analysis was performed using a gas chromatograph CHNS-O elemental analyzer (EURO EA 3000, HEKAtech, Wegberg, Germany). pH was measured with a pH meter (EcoScan pH 5, ThermoFisher Scientific, Waltham, MA, USA) including a glass electrode (Sentix 62, Mettler Toledo, Columbus, OH, USA) that was one-point calibrated with a technical buffer solution (pH 7, Mettler Toledo, Columbus, OH, USA). Samples for total alkalinity and dissolved nutrients were filtered through a 0.22 µm cellulose-acetate syringe filter (Nalgene, Rochester, NY, USA) and stored at 4 °C in 125 mL borosilicate bottles and 15 mL polycarbonate tubes. Total alkalinity was measured by duplicate potentiometric titration using a TitroLine alphaplus autosampler (Schott Instruments, Mainz, Germany) and corrected with certified reference materials from A. Dickson (Scripps Institution of Oceanography, San Diego, CA, USA). The full carbonate system was calculated for tfin using the software CO2sys (Pierrot et al., 2011) with dissociation constants of carbonic acid by Mehrbach et al. (1973), refitted by Dickson and Millero (1987). Dissolved nutrients were measured colorimetrically at on a continuous-flow autoanalyzer (Evolution III, Alliance Instruments, Freilassing, Germany) following standard seawater analytical methods for nitrate and nitrite (Armstrong et al., 1967), phosphate (Eberlein et al., 1987), silicate (Grasshoff et al., 2009), and ammonium (Koroleff et al. 1970). For flow cytometric measurements, 3.5 mL of the sample were preserved with hexamine-buffered formalin (0.5% final concentration) and stored at −80 °C after dark incubation for 15 min. For analysis, samples were thawed at room temperature, vortexed, and measured at a fast speed for three minutes using an Accuri C6 flow cytometer (BD Sciences, Franklin Lakes, NJ, USA) after setting the threshold of the FL-3 channel to 900. Phenotypic diversity (D2) was calculated for each sample based on the flow cytometric fingerprint according to Props et al. (2016), using the values of FSC-H, SSC-H, FL-2, FL-3, and FL-4. Parts of the metadata as well as calculations from it were used in the publication of Ahme et al. (2023). All scripts can be found on GitHub (https://github.com/AntoniaAhme/PS126CommunityExperiment). The sequence data are available at the European Nucleotide Archive (ENA).

Description: The Arctic Ocean is considerably affected by the consequences of global warming, including more extreme seasonal fluctuations in the physical environment. So far, little is known about seasonality in Arctic marine ecosystems in particular microbial dynamics and cycling of organic matter. The limited characterization can be partially attributed to logistic difficulties of sampling in the Arctic Ocean beyond the summer season. Here, we investigated the distribution and composition of dissolved organic matter (DOM), gel particles and heterotrophic bacterial activity in the Fram Strait during summer and autumn. Our results revealed that phytoplankton biomass influenced the concentration and composition of semi-labile dissolved organic carbon (DOC), which strongly decreased from summer to autumn. The seasonal decrease in bioavailability of DOM appeared to be the dominant control on bacterial abundance and activity, while no temperature effect was determined. Additionally, there were clear differences in transparent exopolymer particles (TEP) and Coomassie Blue stainable particles (CSP) dynamics. The amount of TEP and CSP decreased from summer to autumn, but CSP was relatively enriched in both seasons. Our study therewith indicates clear seasonal differences in the microbial cycling of organic matter in the Fram Strait. Our data may help to establish baseline knowledge about seasonal changes in microbial ecosystem dynamics to better assess the impact of environmental change in the warming Arctic Ocean. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning’.

Description: The Arctic Ocean is considerably affected by the consequences of global warming, including more extreme seasonal fluctuations in the physical environment. So far, little is known about seasonality in Arctic marine ecosystems in particular microbial dynamics and cycling of organic matter. The limited characterization can be partially attributed to logistic difficulties of sampling in the Arctic Ocean beyond the summer season. Here, we investigated the distribution and composition of dissolved organic matter (DOM), gel particles and heterotrophic bacterial activity in the Fram Strait during summer and autumn. Our results revealed that phytoplankton biomass influenced the concentration and composition of semi-labile dissolved organic carbon (DOC), which strongly decreased from summer to autumn. The seasonal decrease in bioavailability of DOM appeared to be the dominant control on bacterial abundance and activity, while no temperature effect was determined. Additionally, there were clear differences in transparent exopolymer particles (TEP) and Coomassie Blue stainable particles (CSP) dynamics. The amount of TEP and CSP decreased from summer to autumn, but CSP was relatively enriched in both seasons. Our study therewith indicates clear seasonal differences in the microbial cycling of organic matter in the Fram Strait. Our data may help to establish baseline knowledge about seasonal changes in microbial ecosystem dynamics to better assess the impact of environmental change in the warming Arctic Ocean.