PANGAEA_963565 Quantitative macroalgae survey and kelp morphometry data collected at Hansneset, Kongsfjorden, Spitsbergen in 2021 Düsedau, Luisa; Fredriksen, Stein; Brand, Markus; Fischer, Philipp; Karsten, Ulf; Bischof, Kai; Savoie, Amanda; Bartsch, Inka Quantitative macroalgae survey and kelp morphometry data collected at Hansneset, Kongsfjorden, Spitsbergen in 2021 2026-01-05 PANGAEA Dataset https://doi.pangaea.de/10.1594/PANGAEA.963565 Investigator Luisa Düsedau luisa.duesedau@awi.de Earth Science DATE/TIME DEPTH, water Replicate Size Category Class Species Species, unique identification Individuals Individual association Stipe length Blade length Blade width Leaf area Stipe biomass, wet mass Stipe biomass, dry mass Holdfast biomass, wet mass Holdfast biomass, dry mass Blade biomass, wet mass Blade biomass, dry mass Sporophyll biomass, wet mass Sporophyll biomass, dry mass Biomass, wet mass Biomass, dry mass Stipe age Comment geoscientificInformation Biomass Depth transect Hansneset_KELP_2021 kelp forest leaf area index (LAI) Observation Svalbard Ruler tape Digital camera, Canon, EOS 600D; followed by image analysis software, Schneider et al. 2012, ImageJ Version 2.1.0 Scale, Mettler Toledo, PB3002-S/FACT Delta Range According to Parke (1948) 2021-06-25 2021-07-15 Complete 78.9958 78.9958 11.9872 11.9872 0.0 m (DEPTH, water) 15.0 m (DEPTH, water) FACE-IT Arctic Biodiversity & Livelihoods unrestricted CC-BY-4.0: Creative Commons Attribution 4.0 International English PANGAEA Data Publisher for Earth & Environmental Science https://www.pangaea.de/ Data Center Contact Michael Diepenbroek info@pangaea.de

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Bremen Bremen 28359 Germany online 7807 data points text/tab-separated-values Düsedau, Luisa; Fredriksen, Stein; Brand, Markus; Fischer, Philipp; Karsten, Ulf; Bischof, Kai; Savoie, Amanda; Bartsch, Inka (2024): Kelp forest community structure and demography in Kongsfjorden (Svalbard) across 25 years of Arctic warming. Ecology and Evolution, 14(6), e11606, https://doi.org/10.1002/ece3.11606 Bartsch, Inka; Paar, Martin; Fredriksen, Stein; Schwanitz, Max; Daniel, Claudia; Hop, Haakon; Wiencke, Christian (2016): Changes in kelp forest biomass and depth distribution in Kongsfjorden, Svalbard, between 1996–1998 and 2012–2014 reflect Arctic warming. Polar Biology, 16 pp, https://doi.org/10.1007/s00300-015-1870-1 Hop, Haakon; Wiencke, Christian; Vögele, Barbara; Kovaltchouk, Nikolaj A (2012): Species composition, zonation, and biomass of marine benthic macroalgae in Kongsfjorden, Svalbard. Botanica Marina, 55(4), 399-414, https://doi.org/10.1515/bot-2012-0097

Surveys were performed for macroalgae fresh biomass, dry biomass, leaf area index and kelp morphometry at Hansneset, Blomstrand in Kongsfjorden, Svalbard, from the infralittoral fringe down to 15 m depth in June - August 2021. This dataset is part of a time series currently spanning over 25 years and complements the studies conducted in 1996/98 (Hop et al., 2012, doi:10.1515/bot-2012-0097) and 2012-14 (Bartsch et al., 2016, doi:10.1007/s00300-015-1870-1). The aim was to document changes in Arctic kelp forests dynamics in an Arctic fjord system influenced by glacial melt by repeatedly sampling the same site in a standardized manner. As ocean temperatures in the Arctic have risen substantially and underwater light climate continuously deteriorated over this time period, alterations were observed in the seaweed community, especially kelps as major coastal foundation species. The data file contains a range of standard morphometric measurements of individual kelps (and associated seaweeds) by depth, quadrat (replicate), and species. The taxonomic 'Class' of the species is provided, as well as a 'Category' that shows if the species is a kelp, or was found in the understory of the kelp forest. Within the species column there is a 'Digitate kelps' value. This is due to the complication of the visual similarity of Laminaria digitata and Hedophyllum nigripes. Because these are field data, and the distinction between these species requires genetic lab work, the exact species identification is not possible here. Historically these kelps were considered Laminaria digitata. In some rare cases, the leaf area and/or Total FW and Total DW were measured together for multiple specimens (especially juveniles together with others). When this was done, a comment can be found for that row of data. ** For all details see the full metadata description at "https://doi.pangaea.de/10.1594/PANGAEA.963565"!

http://en.wikipedia.org/wiki/ISO_8601 DATE/TIME https://doi.org/10.1002/ece3.11606 Kelp forest community structure and demography in Kongsfjorden (Svalbard) across 25 years of Arctic warming https://doi.org/10.1007/s00300-015-1870-1 Changes in kelp forest biomass and depth distribution in Kongsfjorden, Svalbard, between 1996–1998 and 2012–2014 reflect Arctic warming https://doi.org/10.1017/S0025315400056071 According to Parke (1948) https://doi.org/10.1515/bot-2012-0097 Species composition, zonation, and biomass of marine benthic macroalgae in Kongsfjorden, Svalbard https://en.wikipedia.org/wiki/Species Species https://www.face-it-project.eu/ FACE-IT DIF 9.4 2026-01-05 2026-04-30