A survey for macroalgal fresh biomass was performed in the high, mid and low intertidal zone at six sites along the fjord axis of Kongsfjorden in June-July 2024. This dataset is part of a space-for-time comparison between low-Arctic Porsangerfjorden in Northern-Norway and high-Arctic Kongsfjorden in Svalbard. The aim was to document differences in macroalgal biomass and community composition between two Arctic fjord systems at different stages of cryosphere loss to understand how benthic vegetation in the high-Arctic will likely develop in the future.

The data contains a fresh biomass data for a range of macroalgal taxa in the intertidal. Macroalgae were identified to the lowest taxonomic level possible. The taxonomic 'Class' of the taxon is provided to indicate if it is a canopy-forming Fucus distichus or which macroalgae lineage the understory taxon belongs to. Within the taxon column there is a 'Dictiosiphon Chordaria', a 'Planosiphon Scytosiphon' and a 'Urospora Ulothrix' value. Because these are field data, and the distinction between these species requires genetic lab work, the exact species identification is not possible.