Nansen Legacy Seasonal Study Q1 2nd March - 25th March 2021 Mesozooplankton Biodiversity

Study Extent

The sampling covers a transect from the central Barents Sea (76N) to the Arctic Ocean (82N) east of Svalbard, including 7 stations (P1 to P7). Each sampling event includes 5 distinct depth layers The depth intervals were from the bottom-200, 200-100, 100-50, 50-20 and 20-0 m. At the deep stations, the sampling depths were from 1000-600, 600-200, 200-50, 50-20 and 20-0 m

Sampling

The dataset contains mesozooplankton abundance (ind/m3). It has been sampled at 5 distinct depths using a Multinet Midi (HydroBios, opening: 0.25m2, net length: 250 cm). Small mesozooplankton were collected with a mesh-size 64 µm and large mesozooplankton were collected with a mesh-size 180 µm. All samples were preserved in 4 % formaldehyde free from acid. PLEASE NOTE: THIS DATASET CONTAINS TWO COMPLETE DATASETS OF ZOOPLANKTON: ONE FOR SMALL MESOZOOPLANKTON (APPROX BODY SIZE BELOW 2 MM) COLLECTED WITH MULTINET 64 µM AND ONE FOR LARGE MESOZOOPLANKTON (APPROX BODY SIZE ABOVE 2 MM) COLLECTED WITH MULTINET 180 µM MESH SIZE. THE INFO ABOUT WHICH NET IS USED CAN BE FOUND IN gearType in extendedMeasurment andFacts USE EITHER 64 UM OR 180 UM DEPENDING ON WHETHER THE FOCUS IS SMALL OR LARGE MESOZOOPLANKTON

Quality Control

The analysis of organisms has been done according to standard procedures used in multiple other studies. The results have been reviewed by several of the researchers listed under resource creators.

Method steps

1. All samples have been analysed at Institute of Oceanology of the Polish Academy of Sciences (IOPAN). The organisms were identified and counted under a stereomicroscope equipped with an ocular micrometer, according to standard procedures (Harris et al. 2000). Small-sized zooplankters (most of Copepoda, juvenile stages of Pteropoda, Euphausiacea, Ostracoda, Amphipoda and Chaetognatha) were identified and counted in sub-samples obtained from the fixed sample volume by automatic pipette (approximately 500 individuals). Large zooplankters (big Copepoda, Pteropoda, Euphausiacea, Ostracoda, Amphipoda, Decapoda, Appendicularia, Chaetognatha, and Pisces larvae) were sorted out and identified from the whole sample. Representatives of Calanus spp. were identified at the species level based on morphology and prosome lengths of individual copepodid stages (Kwasniewski et al. 2003).

Northern Barents Sea