Müller, Oliver; Amargant Arumí, Martí; Olsen, Lasse Mørk; Marquardt, Miriam; Goraguer, Lucie; Tsagaraki, Tatiana M; Bodur, Yasemin V; Petelenz, Elzbieta; Reigstad, Marit; Assmy, Philipp; Jones, Elizabeth M; Vader, Anna; Bratbak, Gunnar; Gradinger, Rolf: Environmental and microbial abundance data from sea ice samples taken during the Nansen Legacy cruises in the Barents Sea between 2019-2021 [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.995983 (dataset in review)
Abstract:
This dataset gives an overview of environmental and biological data including temperature, bulk salinity, brine salinity, brine volume fraction, particulate organic carbon, chlorophyll a concentrations, bacterial production, primary production and the abundance of microorganisms enumerated using flow cytometry (organisms smaller than 20 µm) of sea ice samples, taken during the Nansen Legacy cruises in the Barents Sea between 2019-2021 in March, May, July, August and December. Additional expedition and sampling details can be found in the cruise reports (https://septentrio.uit.no/index.php/nansenlegacy/section/view/cruise-reports) and sampling protocols (https://arvenetternansen.com/sampling-protocol-collection/). We thank the captain and crew of R/V Kronprins Haakon for their support and help during our fieldwork and all persons involved in the sea ice sampling.
The sea-ice stations were located in the northwestern Barents Sea between 79.7 and 82.1°N and 25.0 and 34.3°E. Sea ice was sampled at two to three process (P) stations per cruise in August and December 2019, and in March, May and July 2021 during The Nansen Legacy Seasonal Cruises Q1-Q4 and Joint Cruise JC2-1 (R/V Kronprins Haakon Cruise numbers 2021703, 2021704, 2019706, 2019711 and 2021708, respectively). Although the cruises were not in chronological order, they covered different stages of the seasonal sea-ice cycle.
At each station ice cores were drilled from undeformed level ice areas, with separate cores for physical and biological properties, using a 9 cm (inner diameter) KOVACS ice corer (Mark II coring system). Snow depth, ice thickness and freeboard were measured for each core using a ruler and ice thickness gauge. Temperature was measured immediately after coring every 10 cm along the entire ice core starting 2.5 cm from the top of the core using a VWR temperature sensor. The ice cores for salinity were cut into sections in the field (5 cm sections for the uppermost 20 cm and 10 cm sections for the rest), placed in containers, transported back to the ship and melted without addition of filtered seawater before the salinity was measured using a WTW 3310 conductivity sensor. Brine salinity and brine volume fraction as an indicator of ice permeability were calculated for each ice section from data on sea-ice bulk salinities and sea-ice temperature using the equations given by Cox and Weeks (1983) and Leppäranta and Manninen (1988).
The ice cores for measuring biological properties (Chlorophyll a (Chl-a), particulate organic carbon (POC), flow cytometry (FCM), bacterial production (BP) and net primary production (NPP)) were cut into sections in the field inside a tent for light protection. The following sections, given as lengths from the ice-water interface, were retrieved: 0-3 cm (bottom ice layer), 3-10 cm, 10-20 cm, 20-30 cm, and in 20 cm intervals from there onwards to the top. For biological variables, sections from 2-5 ice cores were pooled (five cores for the lowermost 50 cm of the core and two cores for the larger sections above 50 cm). For NPP we collected the lowermost 0-3 cm sections from two additional ice cores at each station. The ice core sections (except those for NPP) were collected in containers and brought onboard for further processing. Filtered seawater (<0.22 µm) was added (100 ml per 1 cm section) to reduce osmotic stress upon melting and samples were stored in the dark at 4°C until completely melted. The total sample volume was recorded to calculate the dilution factor which has been accounted for in the data presented here. The sample was then distributed for analysis of the different biological properties.
Particulate organic carbon (POC) was filtered (0.3–2 L) onto pre-combusted GF/F filters, frozen, acid-fumed, and analyzed via CHN analyzer. Chlorophyll a (Chl-a) was extracted from filtered samples using 5mL methanol and measured fluorometrically on a calibrated Turner Design 10-AU fluorometer (Turner Designs, USA), including an acidification step (1 M HCl) to determine phaeopigments (Knap et al., 1996). Bacterial production was estimated by incubating samples with tritiated leucine at in situ temperature, followed by TCA fixation and centrifugation. Radioactivity was counted on a Perkin Elmer Liquid Scintillation Analyzer Tri-Carb 2800TR, and leucine incorporation was converted to carbon production using established conversion factors (Simon and Azam, 1989). Net primary productivity (NPP) of sympagic (ice-associated) algae was estimated using the 14C-CO2 uptake method and in situ incubations (Knap et al. 1996). The bottom 3 cm of two ice cores per station were crushed, pooled, and mixed with 0.22 µm filtered surface sea water from the same location immediately after coring. Flow cytometry was used to quantify phytoplankton, heterotrophic nanoflagellates (HNF), and bacteria from water and melted sea ice samples fixed with glutaraldehyde and stored at -80°C. Phytoplankton were analyzed using an Attune® flow cytometer, with fluorescence-based identification; bacteria and HNF were stained with SYBR Green I and analyzed on a FACS Calibur.
Names of size groups of photosynthetic and heterotrophic organisms are in accordance to "Standards and Best Practices For Reporting Flow Cytometry Observations: a technical manual (Version 1.1)" (https://repository.oceanbestpractices.org/handle/11329/2111.2). A short summary is listed here: RedPico = picophytoplankton (1-2 µm); RedNano = Nanophytoplankton (2-20µm), which includes subgroups RedNano_small (2-5 µm), RedNano_large (5-20 µm); OraNano = Cryptophytes; HetNano = heterotrophic nanoflagellates; HetProk = bacteria (and when present archaea); HetLNA = low nucleic acid (LNA) containing bacteria; HetHNA = high nucleic acid (HNA) containing bacteria and HetProk_largeHNA = HNA-bacteria subgroup with very strong fluorescence signal.
Keyword(s):
References:
Cox, G F N; Weeks, W F (1983): Equations for Determining the Gas and Brine Volumes in Sea-Ice Samples. Journal of Glaciology, 29(102), 306-316, https://doi.org/10.3189/S0022143000008364
Knap, Anthony H; Michaels, A; Close, A R; Ducklow, Hugh W; Dickson, Andrew G (1996): Protocols for the Joint Global Ocean Flux Study (JGOFS) Core Measurements. JGOFS, Reprint of the IOC Manuals and Guides No. 29, UNESCO 1994, 19, 210 pp, hdl:10013/epic.27912.d001
Leppäranta, Matti; Manninen, Terhikki (1988): The brine and gas content of sea ice with attention to low salinities and high temperatures. Helsinki, Finland: Finnish Institute of Marine Research, https://hdl.handle.net/1834/23905
Simon, Meinhard; Azam, Farooq (1989): Protein content and protein synthesis rates of planktonic marine bacteria. Marine Ecology Progress Series, 51, 201-213, https://doi.org/10.3354/meps051201
Funding:
Coverage:
Median Latitude: 81.392593 * Median Longitude: 30.743411 * South-bound Latitude: 79.678200 * West-bound Longitude: 24.995200 * North-bound Latitude: 81.995700 * East-bound Longitude: 34.230000
Date/Time Start: 2019-08-17T00:00:00 * Date/Time End: 2021-07-25T00:00:00
Minimum DEPTH, ice/snow: 0.015 m * Maximum DEPTH, ice/snow: 1.570 m
Event(s):
NL_JC2-1_P5 * Latitude: 80.528900 * Longitude: 33.960200 * Date/Time: 2021-07-20T00:00:00 * Campaign: KPH/2021708 (Nansen Legacy Joint cruise 2-1 (JC21)) * Basis: Kronprins Haakon * Method/Device: Ice Coring System, KOVACS ice drilling & coring equipment, Mark II [motorized]
NL_JC2-1_P6 * Latitude: 81.585000 * Longitude: 31.519500 * Date/Time: 2021-07-22T00:00:00 * Campaign: KPH/2021708 (Nansen Legacy Joint cruise 2-1 (JC21)) * Basis: Kronprins Haakon * Method/Device: Ice Coring System, KOVACS ice drilling & coring equipment, Mark II [motorized]
NL_JC2-1_P7 * Latitude: 81.926200 * Longitude: 29.139600 * Date/Time: 2021-07-25T00:00:00 * Campaign: KPH/2021708 (Nansen Legacy Joint cruise 2-1 (JC21)) * Basis: Kronprins Haakon * Method/Device: Ice Coring System, KOVACS ice drilling & coring equipment, Mark II [motorized]
Parameter(s):
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0) (License comes into effect after moratorium ends)
Status:
Curation Level: Enhanced curation (CurationLevelC)
Size:
1578 data points