Towards a regional baseline of Greenland's continental shelf seabed biodiversity

Polar ecosystems are on the forefront of climate change, yet large parts of our polar seas remain unexplored. This affects our ability to detect change in these regions and hampers global science driven conservation efforts. In Greenland, which is heavily reliant on demersal fisheries, this also affects the economy by complicating sustainability certification. Based on a 8-year benthic bycatch monitoring programme recording primarily megabenthos (>1 cm), we provide a first baseline of the benthic ecosystem in Greenland. We calculated richness, rarity, vulnerable marine ecosystem indicator taxon richness (VME) and biomass across 21 % of the Greenlandic EEZ and suggest seven areas to be considered for management effort based on the 75th percentile of sample distribution for richness, rarity and VMEs. We could identify a clear pattern between East and West Greenland primarily driven by a greater abundance of ostur sponges in the East and greater richness and presence of rare species in the West. We identified patterns of geographic-scale richness (Gamma richness) across depth, latitude, distance from coast and temperature and found that richness decreased with latitude and depth and increased towards the shelf-break as expected. Some deviation from these patterns might have been due to sampling bias. Generally, taxa were found to occupy large spatial regions with few endemic or rare species across the study region. This study is the largest assessment of the benthic Greenlandic shelf ecosystem to date and offers essential guidance to policymakers across the Arctic by providing key knowledge on a hitherto understudied area in the Arctic and implementing an easily applicable approach to conservation area selection that is achievable by nations with limited resources.