Owsianowski, Nils; Federwisch, Luisa; Richter, Claudio (2022): Video footage of the bedrock benthos and accompanying oceanographic data recorded along 19 ROV profiles on the fjord flanks near Vancouver Island on the Canadian west coast [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.942294

Remotely Operated Vehicle (ROV) transects providing video footage and oceanographic CTD data of the Canadian West Coast bedrock benthos. The study sites were located in an area between Vancouver Island and the mainland coastal fjords, as well as in the vicinity of Bella Bella. further North. The ROV was launched from small boats anchored near the rocky shoreline. The transects always started at the shore and were conducted perpendicular to the coastline, following the slope of the fjord flanks downwards. We were particularly interested in the glass sponge communities, their abundance and diversity. However, the records also give a comprehensive impression of the unique local cold-water ecology. While warmer freshwater inflows (10 to 15°C) prevailed in the upper water layer (~10m), the ambient seawater conditions below this layer were relatively constant around 8°C down to several hundred meters water depth. These differences are clearly reflected in the predominant flora and fauna, with high incidence of algae near the sea surface. The colder as well as more constant conditions below are influenced by strong tidal currents and provide an excellent habitat for glass sponges, cold-water corals, sea anemones but also for many echinoderms, fish and crustaceans. The V8Sii ROV (Ocean Modules) was equipped with a High Definition (HD) video cameras (Kongsberg oe14-502) on the front. An altimeter (Tritech Micron Echo Sounder) was used to determine the distance between the camera and the object. From this distance (see ROV metadata) and the camera's angle of view of 45° horizontal and 29° vertical, the image dimensions can be derived. Lighting was provided by four LED lights (Bowtech LED- 2400 aluminum). The ROV was equipped with a compass, orientation sensor, obstacle avoidance sonar (Tritech Micron) and an Ultra Short Baseline system (Tritech USBL) to determine its exact underwater position relative to an onboard GPS position. A sled module was attached to the underside of the ROV with a CTD (SeaBird SBE19 plus) and sensors for pH, oxygen, light, fluorescence and a Doppler Velocity Logger (DVL) Teledyne RDI Instruments, Explorer PA) for bottom tracking.