Mean leaf area of macroalgae collected at Hansneset, Kongsfjorden, Spitsbergen in 2012 and 2021

The leaf area of macroalgae was surveyed at Hansneset, Blomstrand in Kongsfjorden, Svalbard, from the 2.5 m down to 15 m depth in summer 2012 and 2021. Our 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 we observed alterations in the seaweed community, especially kelps as major coastal foundation species. This data contains the leaf area index measurements (leaf area [m²]) per species per quadrat (Replicate) at a series of specific depths (Depth [m]) for the years 2012 and 2021 taken at Hansneset, Kongsfjorden, Svalbard. 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 so they are listed with the WORMS code for Laminariales. Historically these kelps were considered Laminaria digitata.