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).

This datasets contributes to a better understanding of diversity in small peracarid crustacean and their possible distribution patterns in remote deep-sea regions. It contains specimen ocurrence records of the taxon Cumacea sampled with diverse benthic gears (epibenthic sledges, box corer) on the Yermak Plateau north of Svalbard during the PASCAL project with RV Polarstern in 2017 and during the IceAGE expedition IceAGE1 in 2011 in deep sea regions of the Nordic GIN-Seas (Greenland, Iceland and Norwegian Sea). The specimens investigated on morphological and molecular basis in this study were sampled in the course of different projects: The IceAGE program (Icelandic marine Animals: Genetics and Ecology, Brix et al. 2014a) is an ongoing research project (IceAGE 2 in 2013, IceAGE-RR in 2018, IceAGE 3 in 2020) which was established as a follow up of the very successful BIOFAR (Biology of the Faroe Islands, Nørrevang et al. 1994; Gerken and Watling 1999) and BIOICE (Benthic Invertebrates of Icelandic waters, Omarsdottir et al. 2013) projects. It is aimed to develop into a long-term study to get an overview of the biodiversity in this extremely diverse region around Iceland with a variety of different habitats and environmental challenges in its adjacent waters. Based on genetic and morphological diversity, it aims to create an inventory of the fauna as elementary knowledge for a comprehensive understanding of possible responses to changing climate conditions in marine environments (Brix et al. 2014a). The focus of the expedition PS106/1 (ARK-XXXI/1.1, 24th of May – 21st of June, 2017) off northern Svalbard onboard the RV Polarstern in course of PASCAL (Physical feedbacks of Arctic PBL, Sea ice, Cloud and Aerosol) was an interdisciplinary approach for studying the interaction of different Arctic feedback mechanisms based on atmospheric, oceanographic, physical and biological studies (Macke and Flores 2018). In this context the vessel was attached to an ice floe during a two-week passive drifting according to the ocean’s current as a preliminary trial-expedition to the first year-round MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition (Sep/2019 – Sep/2020).