Seafloor habitats across geological boundaries in Disko Bay, central West Greenland

In this paper we describe seafloor terrain of nearly the entire Disko Bay region and provide scientific baseline information about surface geology and sedimentary environments that can support the seafloor management plan in Greenland. Our study utilized multiple datasets of multibeam bathymetry and backscatter, seismic profiles and ground-truthing consisting of video footage from drop camera and benthic video sled, as well as sediment samples from grab and corers. Our results revealed that the key geological units in Disko Bay characterize the scale of geomorphic features, which in turn affects the distribution and complexity of habitat zones. The NE sub-region is underlain by Cretaceous sandstone and characterized by large-scale landforms, mainly vast flat areas draped by glacial lineations, bedrock ridges and pockmark fields. This setting promotes less topographically complex habitats, i.e. coarse plain, muddy/sandy plain with dropstones, and muddy plain. The SW sub-region is characterized by Precambrian Gneiss and Paleoproterozoic metasedimentary rocks with complex system of small-scale geomorphic features, such as cross-cutting channels. This results in topographically complex habitats in the area, such as rocky bank, coarse rugged terrain, and rocky slopes. Two distinctive habitat areas, associated with potential gas seeps, i) southern pockmark field and ii) western zoanthid-sponge wall, were discovered at the geological boundary separating the two sub-regions. Our study highlights the importance of seafloor habitat mapping and analyses by providing fundamental geophysical knowledge necessary to comply with long-term sustainable use of marine resources in Greenland

First High‐Resolution Benthic Habitat Map From the Greenland Shelf (Disko Bay Pilot Study)

A healthy ocean where marine habitats and ecosystems are mapped and protected is one of the UN's Sustainable Development Goals to sustainably use marine resources. Our study presents the first high-resolution benthic habitat map from Greenland integrating analyses of multibeam bathymetry and backscatter data, and ground-truth data including video sled, drop camera and day grab. The pilot area of 30 × 20 km is located on the continental shelf in central Disko Bay, West Greenland and all data were collected in a single, 10-day survey. Multibeam bathymetry data were gridded to a 10 × 10 m resolution, whereas backscatter mosaic was built from a 1 × 1 m grid cell to obtain higher resolution manifestation of seafloor properties. Ground-truth data consisted of 14 video transects, 17 drop camera deployments, and 17 sediment samples. Our results were verified with the published shallow seismic and vibrocore data from the Disko Bay region to link the geological background with the sedimentary environment. We distinguished five physical habitats in the area, based on the distribution of sediment types, water depth with general water masses and morphology. In addition, numerous gas seeps alongside pockmarks were observed in the area, as well as recent iceberg ploughmarks. The identified habitats were associated with two basic communities of benthic fauna, linked primarily to the distribution of sediments and representing hard bottom habitats (sessile fauna) and soft bottom habitats (shrimp/polychaetes). Our study is the first step toward mapping the entire seafloor of Disko Bay to provide a scientific context for the management of seafloor and marine resources