Kelp demography and density along the depth gradient monitored at Hansneset, Kongsfjorden, Spitsbergen in 2021

A survey of age class distribution and density of kelps was performed at Hansneset, Blomstrand in Kongsfjorden, Svalbard, at depths of 2.5, 5 and 10m in June - August 2021. This dataset is part of a time series and complements the investigations conducted in 2013 (Bartsch et al., 2016; doi:doi:10.1007/s00300-015-1870-1). The goal 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 in kelp demography were observed. The data contains counts of individual kelps by depth, quadrat (replicate), species, and age class. Kelps younger than 1 year are classed as 'Juveniles', rather than '0years'. The 'Total_Individuals' value is the sum of all kelps of the same species, at the same depth and within the same quadrat (replicate). 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, whereas here they have been classified simply as Laminariales.