High-Arctic intertidal foraminifera, 78°N Spitsbergen

Intertidal foraminifera tend to decline in abundance and species richness toward the poles. Neither their mere existence at high latitudes has been documented nor has their species composition been characterized. To fill this gap, we conducted reconnaissance in the sheltered fjordhead of the Dicksonfjord (78°N). A transect of seven mudflat stations sampled in triplicate revealed a living assemblage consisting of Elphidium albiumbilicatum , Elphidium clavatum , and Elphidium williamsoni . There were no arenaceous species. This northernmost to date assemblage of intertidal foraminifera has little in common with that of the adjacent fjord basin and, therefore, seems to originate from a different source. It rather corresponds to the rotaliid subset of the intertidal fauna of the northern Fennoscandia at 60–70°N. Thus, foraminiferal colonizers of intertidal Spitsbergen have probably arrived from the mainland by means of bird transport, a hypothetical dispersal vector. In addition, we searched for salt-marsh foraminifera in grassed patches above the tidal flat. Even though halophytes are known from the fjords, we found only a not-salt-tolerant grass in the Dicksonfjord with no foraminifera in the roots. So whether there are salt-marsh foraminifera in Spitsbergen remains an open question.