A recent study has shown increased warming in the fjords of west Spitsbergen. Their location is critical, as they are situated along the main northward pathway of Atlantic Water (AW) which is a great source of heat to the Arctic Ocean and the fjords. In the light of ongoing warming, we aim to discuss differences between the fjords under northward transformation of oceanic waters. We compared summer hydrographic conditions in two fjords located in two opposite ends of west Spistbergen: Hornsund in the south and Kongsfjorden in the north. The study is based on high resolution CTD measurements collected during Arctic cruises between 2001 and 2015. The emphasis was put not only on differences in water temperature, salinity and water masses but also the freshwater content (FWC), AW transport and heat delivery to the fjords. In general, the water in Kongsfjorden is on average 18C warmer and its salinity is higher by 0.5 compared to Hornsund. It is also characterized by two times greater transport of AW and heat delivery to the fjord. On the other hand, Hornsund reveals two times higher FWC. Both fjords undergo a gradual warming due to an increased presence of Atlantic origin waters. The ongoing warming is accompanied by an increase in variability of temperature and salinity dependent on the domination of the Sørkapp Current (SC) or the West Spitsbergen Current (WSC) on the West Spitsbergen Shelf (WSS). Nonetheless, Hornsund remains more Arctic-type fjord compared to Kongsfjorden, due to stronger blocking by SC.
A new species of the digenean family Brachycladiidae Odhner, 1905 is described from the bile ducts of a Gervais’ beaked whale Mesoplodon europaeus Gervais (Ziphiidae) stranded on the North Atlantic coast of Florida. These parasites were assigned to Brachycladium Looss, 1899 and differed from other species of the genus in the relative size of the oral and ventral suckers, the form and size of the eggs and their extremely small body size. A canonical discriminant analysis was used to examine differences between these specimens and the smallest available individuals of B. atlanticum (Abril, Balbuena and Raga, 1991) Gibson, 2005, considered the morphologically closest species. The overall results exhibited significant differences between the two samples and a jack-knife classification showed that 96.2% of the specimens were correctly classified to their group. In view of evidence from morphological data, the specimens from M. europaeus are considered as new to science and are designated as Brachycladium parvulum n. sp.
Relationships between the zooplankton community andv arious environmental factors (salinity, temperature, sampling depth and bottom depth) were established in the European Arctic Marginal Ice Zone (MIZ) using multivariate statistics. Three main zooplankton communities were identified: an Atlantic Shallow Community (AtSC), an Arctic Shallow Community (ArSC) anda Deep Water Community (DWC). All species belonging to AtSC andArSC were pooledandtheir relative abundances in the total zooplankton calculated with respect to a particular layer (surface, midan dd eep strata), regions (the Barents Sea, Fram Strait andt he waters off northern Svalbard), years (1999 or 2003) and seasons (spring or autumn). Mapping of the proportions of Arctic andA tlantic species ledto the conclusion that zooplankton from the MIZs do not exactly follow complementary water masses, although the general pattern of AtSC and ArSC dominance accords with the physical oceanography of the study area (AtW and ArW respectively). The mid layer proved to be a better predictor of mesozooplankton distribution than the unstable conditions near the surface.
This study examines the performance of pelagic and benthic Malacostraca in two glacial fjords of west Spitsbergen: Kongsfjorden, strongly influenced by warm Atlantic waters, and Hornsund which, because of the strong impact of the cold Sørkapp Current, has more of an Arctic character. The material was collected during 12 summer expeditions organized from 1997 to 2013. In all, 24 pelagic and 116 benthic taxa were recorded, most of them widely distributed Arctic-boreal species. The advection of different water masses from the shelf had a direct impact on the structure of the pelagic Malacostraca communities, resulting in the clear dominance of the sub-arctic hyperiid amphipod Themisto abyssorum in Kongsfjorden and the great abundance of Decapoda larvae in Hornsund. The taxonomic, functional and size compositions of the benthic malacostracan assemblages varied between the two fjords, and also between the glacier-proximate inner bays and the main fjord basins, as a result of the varying dominance patterns of the same assemblage of species. There was a significant drop in species richness in the strongly disturbed glacial bays of both fjords, but only in Hornsund was this accompanied by a significant decrease in density and diversity, probably due to greater isolation and poorer quality of sediment organic matter in its innermost basin. Our results suggest that the diversity and distribution of benthic malacostracans in these two fjords are only distantly related to the different hydrological regimes; rather, they are governed by locally acting factors, such as depth, sediment type, the variety of microhabitats and the availability and quality of food.
Since 1987 annual summer cruises to the Nordic Seas and Fram Strait have been conducted by the IO PAN research vessel Oceania under the long-term monitoring program AREX. Here we present a short description of measurements and preliminary results obtained during the open ocean part of the AREX 2016 cruise. Spatial distributions of Atlantic water temperature and salinity in 2016 are similar to their long-term mean fields except for warmer recirculation of Atlantic water in the northern Fram Strait. The longest observation record from the section N along 768300N reveals a steady increase of Atlantic water salinity, while temperature trend depends strongly on parametrization used to define the Atlantic water layer. However spatially averaged temperature at different depths indicate an increase of Atlantic water temperature in the whole layer from the surface down to 1000 m.
Brasilochondria riograndensis Thatcher et Pereira, 2004 (Copepoda, Chondracanthidae) is redescribed based on newly collected material from the branchial cavity of flounder, Paralichthys orbignyanus (Valenciennes, 1842), from the coasts of Buenos Aires Province, Argentina. A number of details were overlooked and some appendages were misidentified in original description and are included herein. These are: the distribution and the number of setae and spines in the antennule, the armature and segmentation of mandible, maxillule, maxilla, and maxilliped, pedigerous segments and genitoabdomen, in both, females and males. Moreover, the geographical distribution of this parasite species is broadened.
The water masses in Fram Strait have been analyzed on the basis of hydrographic casts taken in summer 1984 during the MIZEX 84 experiment. In particular, θ − S diagrams for 16 areas, each 5◦ in longitude and 1◦ in latitude, covering the strait from 77◦N to 81◦ N are used to characterize the water masses and discuss their possible origin. Near the surface, the East Greenland Polar Front clearly separates the lighter, cold and fresh Polar Water (PW) from the heavier, warm and saline Atlantic Water (AW). In the upper ocean, the data show a large spreading of the temperature maximum in the θ − S space associated with different modes of the AW recirculating southward below the PW. Two geographically distinct salinity minima are found in the intermediate layer below the AW. The denser one, in the Boreas Basin, is a feature typical of the Arctic Intermediate Water (AIW) formed by winter convection to the south of the strait, while the lighter one is sandwiched in the Arctic Ocean outflow between the AW layer and the Upper Polar Deep Water (UPDW) characterized by a downward salinity increase. In the deep layer, two salinity maxima are present. The shallower (and warmer) one, associated with the Canadian Basin Deep Water (CBDW), appears all along the East Greenland Slope. A similar but weaker maximum is also found in the southeastern part of the strait. This maximum is perhaps a remnant of the maximum in the East Greenland Current after it has been recirculated back to the strait around the cyclonic gyres of the Nordic Seas. The deeper one appears typically as a near-bottom salinity jump characteristic of the Eurasian Basin Deep Water (EBDW). The jump is found in two distinct areas of the strait, to the north-west in the Lena Trough and to the south-east in the rift valley of the Knipovich Ridge. The maximum in the former area should have been advected from the Arctic Ocean below the CBDW, while the maximum in the latter area might have originated from haline convection on the adjacent shelves. Some EBDW is trapped in the Molloy Deep over a denser water with salinity decreasing down to the bottom and temperature in the range of the Greenland Sea Deep Water (GSDW).
Two Spitsbergen fjords, Hornsund and Kongsfjorden, are known for being under different hydrological regimes. The first is cold, separated from warm Atlantic water by East Spitsbergen Current, while Kongsfjorden is frequently penetrated by relatively warm Atlantic water. On the other hand, both are under strong influence of water discharge from glaciers and land freshwater input. During the period of observation in both fjords a dominant water mass was Surface Water, which originates mainly from glacial melt. The presence of suspended matter introduced with melt water in Surface Water is reflected by highest values of light attenuation and absorption coefficients recorded in areas close to glacier both in Hornsund and Kongsfjorden. In Hornsund the maximum light attenuation coefficient cpg(555) was 5.817 m−1 and coefficient of light absorption by particles ap(676) = 0.10 m−1. In Kongsfjorden the corresponding values were 26.5 m−1 and 0.223 m−1. In Kongsfjorden suspended matter of the size class 20–200 μm dominated over fractions smaller than 20 μm while in Hornsund dominating size fraction was 2–20 μm. The results provide an evidence of considerable range of variability of the optical properties mainly due to glacial and riverine runoff. The scale of variability of particulate matter in Kongsfjorden is bigger than in Hornsund. Most of the variability in Hornsund can be attributed to glaciers discharge and a presence of particles of mineral origin, while in Kongsfjorden the organic and mineral particles contribute almost equally to defining the optical properties of water.
A new dataset of benthic foraminiferal assemblages from Adventfjorden (tributary fjord of Isfjorden, West Spitsbergen) was compared with the results of a study conducted by Zajączkowski et al. (2010) in Hornsund (West Spitsbergen). According to Nilsen et al. (2016), Atlantic water inflow to the Isfjorden Trough occurs more readily than to anywhere else along the shelf of Spitsbergen; thus, we compared the foraminiferal assemblages of the outwash Adventfjorden fjord, located in the Isfjorden system, with glacial Hornsund, located in southwest Spitsbergen. Despite the juxtaposition of Adventfjorden and Hornsund the data revealed varying impacts of shelf-transformed water (STW) on the benthic foraminiferal assemblages. Outer and central Adventfjorden was dominated by Adercotryma glomerata, Recurvoides turbinata and Spiroplectammina sp., reflecting the presence of STW, while abundant Melonis barleeanus in the central area of the fjord indicated a large flux of unaltered organic matter. Only the head of the fjord was dominated by the glaciomarine taxa Cassidulina reniforme and Elphidium clavatum. Foraminiferal fauna characteristic of STW-influenced environments (i.e., Nonionellina labradorica and R. turbinata) were also observed in outer Hornsund. However, the glacier-proximal taxa E. clavatum and C. reniforme were dominant throughout the fjord, demonstrating the impacts of meltwater and high sedimentation. Therefore, it is likely that in Hornsund, glacial impact is a major environmental factor, which is stronger than the influence of STW.
The circulation of Atlantic water along the European continental slope, in particular the inflow into the North Sea, influences North Sea water characteristics with consequent changes in the environment affecting plankton community dynamics. The long-term effect of fluctuating oceanographic conditions on the North Sea pelagic ecosystem is assessed. It is shown that (i) there are similar regime shifts in the inflow through the northern North Sea and in Sea Surface Temperature, (ii) long-term phytoplankton trends are influenced by the inflow only in some North Sea regions, and (iii) the spatial variability in chemicophysical and biological parameters highlight the influence of smaller scale processes.
For many years the Nordic Seas have been the subject of research into ocean circulation carried out by the Institute of Oceanology PAS, especially the inflow of Atlantic water and the intensive turbulent mixing of these waters with Arctic and shelf waters. Ocean currents affect various biological processes, among them the supply of organic matter and oxygen, which constitute the foundation for the unique flora and fauna of the Svalbard islands. Spectrophotometric examinations of surface waters using an M32 B spectroflu- orophotometer (LDI Ltd.) were carried out repeatedly during Arctic cruises on board r/v ‘Oceania’. The results presented in this paper come from the AREX campaigns of 2003 and 2006. Analysis of the chlorophyll a fluorescence excitation spectra recorded shows an increase in phytoplankton abundance and the changes in the spatial distribution of the phytoplankton species characteristic of Atlantic, Arctic and shelf waters. The spatial patterns of the phytoplankton pigments and their abundance were compared with the physical characteristics of water masses. The analysis confirmed that phytoplankton species move together with the Atlantic water as this flows into northern latitudes.
Zooplankton inhabiting the Hornsund and Kongsfjorden fjords on Spitsbergen (Svalbard) were investigated in summer 2013. The goal of the study was to determine how the zooplankton communities vary in environments functioning under different oceanographic regimes. Sampling was conducted with nets of different mesh size and selectivity (56 μm WP-2, 180 μm MultiNet, and 1000 μm Tucker Trawl), which permitted comparing a wide size spectrum of zooplankton components. Species composition did not differ substantially between the fjords, but the zooplankton in Hornsund was almost two times less numerous, and it had lower biomass per unit volume. The highest abundance at both sites was in the smallest zooplankton size fraction found only in samples taken with 56 μm mesh WP-2 net. These comprised as much as 71% and 58% of the total zooplankton abundance in Hornsund and Kongsfjorden, respectively. The communities in both fjords had comparable contributions of Arctic and boreo-Arctic species biomass in the year of the study. However, the comparison of zooplankton characteristics over several years showed changes in abundance and biogeographic structure that corresponded with variations in the physical environments of the fjords. The results of the study permit predicting the possible effects of the increasing influence of Atlantic waters on zooplankton communities inhabiting Arctic marine pelagic ecosystems.