DOI: 10.5285/e115d087-e3e4-4794-b4e0-18262b8e6400
title: Benthic, epibenthic and pelagic marine invertebrate specimens collected during PS136 in the Arctic Fram Strait in 2023 and their individual lipid profiles and bulk isotopes

description: During the expedition PS136 LTER HAUSGARTEN in 2023 105 samples of macrobenthic marine invertebrates and 3 samples of calanoid copepods were collected by epibenthic sledge and 28 samples of calanoid copepods were collected by Bongo and Multinet and subsequently frozen at -80 degrees Celsius for lipid and bulk stable isotope analyses. Katrin Linse, Saskia Brix, Jannifer Freer and Lydia Anastasia Schmidt collected, photographed and fixed the specimens on board. The macrobenthic invertebrates and calanoid copepods were collected to study elements of the biological lipid pump in the Arctic Ocean.
The preparation and lab analyses of the lipid biomarker and stable isotope data were carried out by Rachel Jeffreys and Sabena Jane Blackbird at the University of Liverpool using Gas chromatography-mass spectrometry and an ECS8020 elemental analyser (NC Technologies) coupled to a Delta V isotope ratio mass spectrometer.
Statistical analyses and interpretation of lipid biomarker and stable isotope data were carried out by Dewi Ford, Dan Mayor and Anna K. Wadsworth at the University of Exeter.
The raw data files include lipid biomarker and stable isotope data for all analysed macrobenthic invertebrates and calanoid copepods, while the processed data files include all calanoid copepod data but selected macrobenthic taxa only, being Amphipoda, Decapoda, Isopoda, Mysidacea, Holothuroidea, Ophiuroidea, and Chaetognatha.

The contributions of KL, JF and DJM were supported by the BIOPOLE National Capability Multicentre Round 2 funding from the Natural Environment Research Council (grant no. NE/W004933/1). DJM also received funding from OceanICU (EU Grant agreement ID: 101083922; UKRI grant reference: 10063673). SB received support via the Leibniz foundation and the ALONGate project (A Long-term Observatory of the North Atlantic Gateway to the Arctic Ocean) via grant number PS150/2023 in the program for women professors.
The field work for PS136 was supported by grant no. AWI_PS136_01.
description: The marine invertebrates were collected during the RV Polarstern expedition PS136.
The pelagic copepods Calanus finmarchicus and Calanus hyperboreus were collected using a BONGO net and a Multi-net.
Benthic and epibenthic marine invertebrates were collected using an epibenthic sledge.
Specimens for lipid and bulks stable isotope analyses were sorted live, photographed and fixed -80 °C in cryovials.
Lipid extractions and Gas chromatography-mass spectrometry (GC-MS) analyses were carried out in the Jeffreys' lab at the University of Liverpool following their standard protocol. Compounds were identified either by comparison of their mass spectra and relative retention indices with those available in the literature, and/or by comparison with authentic standards. Shorthand notations of fatty acids and alcohols follows the IUPAC (International Union of Pure and Applied Chemistry, hhtp://www.iupac.org) systematic nomenclature 'n-x' notation.
Quantitative data were calculated by comparison of peak areas of the internal standard with those of the compounds of interest, using the total ion current (TIC) chromatogram. The relative response factors of the analytes were determined individually for 36 representative fatty acids and sterols using authentic standards. Response factors for analytes where standards were unavailable were assumed to be identical to those of available compounds of the same class.
Bulk stable isotope analyses were carried out in the Jeffreys' lab at the University of Liverpool following their standard protocol. Isotope values were corrected using internationally certified isotopic reference materials USGS40 and USGS41a (Reston Stable Isotope Laboratory) and are reported in delta-notation (per mille) relative to atmospheric nitrogen (N2) and Vienna PeeDee Belemnite carbonate (V-PDB) scales. An internal standard of homogenized prawn (Penaeus vannamei) with well characterized d15N values (6.50 per mille +/- 0.16 per mille) was used to measure precision.
In the data analyses Quantitative lipid constituent data were separated into three datasets which included lipid compound groups (e.g., saturated fatty acids, monounsaturated fatty acids), individual fatty acids, and individual fatty alcohols. These data were converted to relative abundance (mol%) of total identified lipid compounds, fatty acids, or fatty alcohols, respectively. The relative abundance of fatty acid isomers with the same number of carbon molecules and double bounds but unidentified omega groups were summed and labelled as 'X1:X2(iso)'.
description: The epibenthic sledge used for the collection of the benthic invertebrates was DZMB Senckenberg Wilhelmshaven build following the design by Brenke (2005).
Gas chromatography-mass spectrometry (GC-MS) analyses of the total lipid extracts were conducted using a GC Trace 1300 fitted with a split-splitless injector and column DB-5MS. The eluent from the GC was transferred directly via a transfer line (320 degrees Celsius) to the electron impact source of a Thermoquest ISQMS single quadrupole mass spectrometer. Mass data were collected at a resolution of 600, cycling every second from 50 to 600 Da and were processed using Xcalibur software.
Bulk stable isotope samples were analysed following acid vapour treatment (HCL; 12 h; Yamamuro and Kayanne, 1995), using an ECS8020 elemental analyser (NC Technologies) coupled to a Delta V isotope ratio mass spectrometer (Thermo Scientific).
description: The identification to species in the calanoid copepods were carried out by experienced zooplankton scientists, while the macrobenthic invertebrates were consistently identified to higher taxonomic levels (Phylum, class, order) but only selected specimens identified to Genus or species.
Lipid and bulk stable isotope data were quality controlled using standards.