Benthic Foraminifera in Adventfjorden, Svalbard; last 50 years of local hydrographic changes

Three marine sediment cores in Adventfjorden, west Spitsbergen, Svalbard, were analyzed for granulometry and benthic foraminifera (>125 mu m). Summer water temperature and salinity, as well as suspended solid concentration, were measured. The benthic foraminifera from Adventfjorden are comprised of 46 species belonging to 37 genera. The observed succession of these follows the general distribution pattern of near-shore Svalbard species. The most near-shore Cribroelphidium excavatum clavatum is followed by the more distant Spiroplectammina earlandi, Ammotium cassis, Labrospira crassimargo and Recurvoides turbinatus. Present summer salinity and temperature show no major changes near the sea floor along the Adventfjorden transect. The benthic foraminiferal assemblages appear to be related to different sedimentation regimes, and varied through time with changes in sedimentation. The assemblage changes during approximately 1959-1963 and approximately 1977-1987 seem to be linked to local conditions, especially summer precipitation in the area. Conditions causing the possible poor carbonate preservation in Adventfjorden could be due to the reduced sedimentation rates and/or descent of brines produced by sea-ice formation, coupled with decay of organic matter, but not directly to the influence of low-saline water.