Littoral bryozoan communities in the high Arctic: a latitudinal comparison.

The littoral bryozoan communities in the Barents and Greenland Seas have not received as much attention as their deep-water communities. To address this gap, we compared the diversity and biomass patterns of bryozoans across two localities: Eastern Murman (EM), (southern Barents Sea, 69°N) and Grønfjorden (GF), Svalbard (Greenland Sea, 78°N). The study revealed moderate dissimilarity in habitat conditions. Boreo-Arctic species were the most common at both sites, but the proportion of boreal species was higher in EM (28 vs. 7.5%). Biomass tended to be higher at higher latitudes. Multivariate analyses revealed a significant dissimilarity of 94.1% between bryozoan communities at the two study sites. Redundancy analysis demonstrated that substrate type was the primary driving force for bryozoans in GF, whereas diversity indices were positively associated with salinity in EM, and bryozoan biomasses were negatively scaled to temperature. These differences may be attributed to the more stressful conditions in EM, where thermal stress may act as an initial stressor, leading to a reduction in salinity levels that negatively impact bryozoans, rendering them unable to survive in less saline water as they do in GF under more optimal temperature conditions.