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Category: Data

Description: During the Polastern expedition PS101 a giant sponge ground was discovered on the peaks of the Langseth Ridge seamounts (600 m depth, 87°N, 61°E), representing the densest benthic biomass found to date for Arctic deep-sea environments. The three sponge species that composed the bulk of the visible sponge biomass were Geodia parva, G. hentscheli and Stelletta rhaphidiophora, resembling the community composition of a typical Arctic-Boreal Geodia ground. The sponge abundance was visually characterized through image analysis. Four Ocean Floor Observation and Bathymetry System (OFOBS) deployments (dive cruise stations 89, 100, 120, 169) collected 3.2 km of video, still image and sidescan transects. These downloadable data files “Density data set_Karasik sponges” and “Biomass Karasik sponges” contain sponge count and measurements (width and length) over the three summits that composed the Langseth Ridge.