Distribution and abundance of pteropods in the western Barents Sea

The abundance and horizontal distribution of three pteropod species, Limacina helicina, Limacina retroversa and Clione limacina were examined in the western entrance of the Barents Sea (Polar Front region) in August 2011. Sixteen samples were collected from 8 sampling sites located along a latitudinal transect. The southern part of the study area (south of 73°N) was dominated by L. retroversa, while L. helicina was mostly observed north of 73°N. Surface water temperature differences between the coldest and the warmest station were around 8°C. The highest density of L. retroversa was found in the south, near the Norwegian coast (nearly 52 000 ind. 1000 m⁻³), while the highest density of L. helicina was observed in the region of the Arctic water masses (nearly 13 000 ind. 1000 m⁻³). The sampled population of pteropods comprised mainly juvenile stages. Redundancy analysis (RDA) of the relationships between environmental factors (mean and surface salinity, mean temperature, sampling depth, chlorophyll concentration) and the population structure showed that mean temperature was the most important factor in the study area, explaining 70.5% of the pteropod community variation.