Long-term measurements of sea water properties collected by sensor buoy in Adventfjorden as part of the Svalbard Integrated Arctic Earth Observing System (SIOS).

The Aurora seamount and hydrothermal field, located in the western Gakkel Ridge of the Central Arctic Ocean, was first identified in 2001. The dataset presented here was collected during the HACON19 research cruise onboard of the RV Kronprins Haakon, as part the international HACON project (Hot vents in an ice-covered ocean: the role of the Arctic as a connectivity pathway between ocean basins). This campaign used the Ocean Floor Observation and Bathymetry System (OFOBS), which is a towed underwater sled equipped with high-resolution still and video cameras. This dataset provides density data (individuals per square meter) for benthic megafauna (organisms greater than 2 cm) inhabiting the Aurora Seamount, its hydrothermal vent field, and surrounding areas. The data were collected between October 1 and October 15, 2019. In addition to the biological density measurements, the dataset includes environmental context information such as observation depth and substrate type. Sampling methods:Observations were identified based on still image frames collected along several exploratory transects, and captured by a towed camera system (Ocean Floor Observation and Bathymetry System – OFOBS), which was equipped with both a high-resolution still camera and a high-definition video camera.Method step description:Each still image was annotated using the online annotation platform BIIGLE (Langenkämper et al., 2017; https://biigle.de) for the identification and quantification of all living benthic megafauna organisms (-gt;2cm), seafloor substrate type, and description of any other seafloor characteristics. Acknowledgements:AURORA: Bringing Deep-Sea Biodiversity Data to Light. Funded through the DTO-BioFlow project, which is supported by the European Union (Grant Agreement No. 101112823). HACON project - Hot vents in an ice-covered ocean: the role of the Arctic as a connectivity pathway between ocean basins, funded by FRINATEK call in the FRIPRO programme of the Research Council of Norway and coordinated by NIVA. Data creators are also funded by national funds through FCT – Fundação para a Ciência e a Tecnologia I.P., under the project CESAM-Centro de Estudos do Ambiente e do Mar, references UID/50017/2025 (doi.org/10.54499/UID/50017/2025) and LA/P/0094/2020 (doi.org/10.54499/LA/P/0094/2020).