During the cruise of the research ship r/v Oceania owned by the Institute of Oceanology of the Polish Academy of Sciences in Sopot a research on mineral suspension concentration and dispersion distributions was conducted. The research area included the western part of the Baltic Sea, the Danish Straits, the Norwegian Sea, the waters around Spitsbergen and the North Atlantic Ocean. Samples of water were collected from the surface layer. They were subjected to microscopic analysis. Measurements were done with a projection microscope (magnification lOOOx) and using the Burker's table. After counting the particles dispersion distribution was determined. The largest concentration of mineral suspension was noted offshore in the Norwegian Sea and around Spitsbergen and the smallest in the central Atlantic Ocean.
The Pleistocene and post−Pleistocene evolutionary history of many North Atlantic intertidal invertebrate species is well known, but the evolutionary history of the deep North Atlantic fauna is poorly understood, specifically whether colonization of the deep North Atlantic paralleled the patterns observed in shallow water. Contemporary pan−Atlantic species distributions could result from several colonization pathways that connected different regions of the Atlantic at different times ( e.g. Arctic, Antarctic or Panamanian path− ways). To test potential colonization pathways we quantified geographic variation in nu− clear and mitochondrial markers from Atlantic samples of Nucula atacellana, a pan−Atlantic deep−sea protobranch bivalve, using N. profundorum in the eastern central Pacific as an outgroup. We combined existing 16S data from North and South Atlantic populations of N. atacellana with new sequences of 16S, COI, and an intron of calmodulin from those populations, and newly sampled populations near Iceland. Population genetic analyses indicated a subtropical expansion via the Central American Seaway. We found no evidence for Transarctic migration to the Atlantic in N. atacellana , which suggests that colonization pathways may differ significantly between shallow− and deep−water fauna.
During the IceAGE ( Icelandic marine Animals – Genetics and Ecology ) expeditions in waters around Iceland and the Faroe Islands in 2011 and 2013, visual assessments of habitats and the study of surface sediment characteristics were undertaken in 119–2750 m water depth. Visual inspection was realized by means of an epibenthic sled equipped with a digital underwater video camcorder and a still camera. For determination of surface sediment characteristics a subsample of sediment from box corer samples or different grabs was collected and analyzed in the lab. Muddy bottoms predominated in the deep basins (Iceland Basin, Irminger Basin, deep Norwegian and Iceland Seas), while sand and gravel dominated on the shelves and the ridges, and in areas with high currents. Organic contents were highest in the deep Norwegian and Iceland Seas and in the Iceland Basin, and at these sites dense aggregations of mobile epibenthic organisms were observed. Large dropstones were abundant in the Iceland Sea near the shelf and in the Denmark Strait. The dropstones carried diverse, sessile epibenthic fauna, which may be underestimated using traditional sampling gear. The paper supplies new background information for studies based on IceAGE material, especially studies related to ecology and taxonomy.
The coreless winters ( i.e. not having a cold core) were distinguished in four stations within the European sector of the Arctic. Anomalies of the frequency of the Niedźwiedź’s (2011) circulation types were calculated separately for the mid−winter warm months and for cold months preceding and following the warm−spells. Furthermore, composite and anomaly maps of the sea level pressure as s well as anomaly maps of the air temperature at 850 gpm (geopotential meters) were constructed separately for the mid−winter warm events and for the cold months before and after warming. Different pressure patterns were recognized among the days of mid−winter warm spells, using the clustering method. The occurrence of coreless winters in the study area seems to be highly controlled by the position, extension and intensity of large scale atmospheric systems, mainly the Icelandic Low. When the Low spreads to the east and its centre locates over the Barents Sea the inflow of air masses from the northern quadrant is observed over the North Atlantic. This brings cold air of Arctic origin to the islands and causes an essential drop in the air temperature. Such situation takes place during the cold months preceding and following the warm mid−winter events. During the warm spells the Icelandic Low gets deeper−than−usual and it is pushed to the northeast, which contributes to the air inflow from the southern quadrant.