Taxonomy and vertical export rates of protist cells, planktonic protist carbon (PPC) and zooplankton abundance and biomass from long-term sediment traps in the shelves north and east of Svalbard, as part of the Nansen Legacy project and the Arctic PRIZE project

This dataset includes taxonomy and vertical export rates of zooplankton abundance and biomass from long-term sediment traps between October 2017 and September 2018. Samples were collected from 2 moorings as part of the Arctic PRIZE project (SAMS, UK) and the sediment traps were processed as part of the Nansen Legacy project (UiT, NO). Records in the dataset can be divided into 2 moorings by the locationID column, either ESv (shelf east of Svalbard) or NSv (shelf north of Svalbard).

For the ESv mooring, the mooring was deployed in 183 m water depth on 21 September 2017 north of Svalbard from the R/V Lance (A-TWAIN cruise). The mooring was recovered by the R/V James Clark Ross (JR17006) on the 17 June 2018 and sensor data were retrieved and instrument batteries replaced for redeployment on the 20 June 2018. A final recovery of all sensors was done by the R/V Kronprins Haakon (Nansen-Legacy cruise) on 18 November 2019.

For the NSv mooring, the mooring was deployed in 234 m of water on 23 September 2017 north of Svalbard from the R/V Lance (A-TWAIN cruise). The mooring was recovered by the R/V James Clark Ross (JR17006) on the 14 June 2018 and sensor data were retrieved and instrument batteries replaced for redeployment on the 22 June 2018. A final recovery of all sensors was done by the R/V Kronprins Haakon (Nansen-Legacy cruise) on 25 November 2019.

Samples were taken from a long-term sequential sediment trap bottles (McLane Research Laboratories Inc., 21 bottles, aperture area of 0.5 m^2). Sample bottles (500 mL) were programmed to rotate at intervals ranging from 7 to 31 days. Sample bottles were filled with filtered seawater poisoned with formalin (4% v/v), with the salinity adjusted to 40 by adding NaCl.

For the zooplankton, subsamples (100-150 mL) were taken for the analysis of a minimum of 300 zooplankton. Zooplankton were identified to the lowest taxonomic level possible using a stereomicroscope (Zeiss Discovery V20) and measured with an accuracy of 10 μm using the ZoopBiom digitizing system (Roff & Hopcroft, 1986). Biomass (dry weight) was estimated using published length-weight regressions for these or similar species (Ershova et al., 2015). The dry weight of each taxon was then converted to carbon weight following Kiørboe (2013). Species were also classified by biogeographic affinity.

Samples (0.5-2 ml) for planktonic protists identification were settled in Utermöhl sedimentation chambers for 24 h. Settled protists were counted using an inverted microscope equipped with phase and interference contrasts (Nikon Eclipse TE-300). Microplankton (>20 μm) was enumerated from the entire chamber surface at 100× magnification. Nanoplanktonic protists (3–20 μm) were counted at 400× magnification by moving the field of view along the length of three transverse transects (in special cases a magnification of 600× was used for taxonomic identification). The taxa were identified to the lowest taxonomic level possible following the World Register of Marine Species (WoRMS). Planktonic protist carbon (PPC) was calculated by multiplying the cell counts of individual cells and resting spores by the associated carbon content of each species or group depending on cell sizes (Menden-Deuer & Lessard, 2000).

All daily fluxes (vertical export rates) were calculated depending on the volume of the subsamples, the trap area (0,5 m), and the sampling duration.