During the AO2024 expedition (19 July to 12 August 2024), Melosira assemblages were collected using a handheld net at two sampling sites in the Amundsen Basin. Pelagic particulate organic matter (PPOM) was sampled at 13 stations spanning the Amundsen and Nansen Basins as well as the Gakkel Ridge, using Niskin bottles mounted on a CTD rosette. During the AO2024 expedition (19 July to 12 August 2024), Melosira assemblages were collected using a handheld net at two sampling sites in the Amundsen Basin. Pelagic particulate organic matter (PPOM) was sampled at 13 stations spanning the Amundsen and Nansen Basins as well as the Gakkel Ridge, using Niskin bottles mounted on a CTD rosette. Between 3 and 6.5 L of seawater were filtered through GF/F filters. Ice-associated POM was obtained using a Kovacs 9 cm ice corer at one station each in the Amundsen and Nansen Basins; the bottom 10 cm of each ice core were melted with the addition of filtered seawater and filtered onto GF/F filters.Lipids were extracted from freeze-dried samples following the method of Folch et al. (1957), using a dichloromethane/methanol mixture (2:1, v/v) in a sonication bath. The extracted lipids were converted to fatty acid methyl esters (FAMEs) and analyzed by gas chromatography (Agilent 6890N Network GC, Agilent Technologies) equipped with a DB-FFAP capillary column (30 m length, 0.25 mm inner diameter, 0.25 μm film thickness), split injection, and a flame ionization detector. The temperature program ranged from 160°C to 240°C.Carbon stable isotope ratios (δ13C) were measured directly from fatty acid extracts for selected fatty acids—14:0, 16:0, 16:1(n-7), and 20:5(n-3)—using a Thermo GC-c-IRMS system. This setup included a Trace GC Ultra gas chromatograph, a GC Isolink interface, and a Delta V Plus isotope ratio mass spectrometer, all connected via a Conflo IV interface (Thermo Scientific). FAMEs, dissolved in hexane, were injected in splitless mode and separated on a DB-FFAP capillary column (60 m length, 0.25 mm inner diameter, 0.25 μm film thickness). Measurements were calibrated using reference materials (C18:0, C20:0). Samples were analysed in triplicates.Stable isotope analysis was conducted to complement datasets on fatty acid and sterol proportions. Collectively, the datasets enable a detailed characterization of the biochemical composition of different algal assemblages across the central Arctic Ocean.