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.
