Recent distribution of planktonic foraminifera in the Nansen Basin, Arctic Ocean

Planktonic foraminifera were collected in the Arctic Ocean with net tows (>63 μin) along a S-N transect from 81 to 86°N. Five depth intervals were sampled vertically between 500 m water depth and the sea surface. The most common species are Neogloboquadrina pachyderma and Globigerina quinqueloba. Based on the depth habitat, the faunal composition and the population structure, the planktonic foraminifera can be divided into two distinct provinces having a latitudinal boundary at 83°N. In the southern area, the concentrations of planktonic foraminifera are highest as well as the per cent of subpolar species and right-coiling individuals. Both species prefer the water below the pycnocline at about 100 m. North of 83°N, the two species display maximum abundance in the upper 50 m, where the water is colder and fresher than below the pycnocline. The proportions of right-coiling individuals and subpolar species are decreasing going northward. The observed changes are caused by the input of Atlantic water masses transported into the Arctic Ocean.