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Impact of shelf-transformed waters (STW) on foraminiferal assemblages in the outwash and glacial fjords of Adventfjorden and Hornsund, Svalbard

Szymańska N., Pawłowska J., Kucharska M., Kujawa A., Łącka M., Zajączkowski M.

Oceanologia

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2017

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No. 59 (4)

525--540

EN

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.

2

Ecosystem maturation follows the warming of the Arctic fjords

Węsławski J. M., Buchholz F., Głuchowska M., Weydmann A.

Oceanologia

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2017

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No. 59 (4)

592--602

EN

Two fjords in West Spitsbergen (Hornsund 77°N and Kongsfjorden 79°N) differ with regard to their exposure towards increasingly warm Atlantic water inflow. Hornsund remains in many respects cooler than Kongsfjorden (on average 2°C SST in summer) and is less influenced by warmer and more saline Atlantic waters. Reported changes in the physical environment (temperature rise, freshwater inflow, salinity drop, turbidity, fast-ice reduction, coastal change) are discussed in the context of biological observations in the pelagic and benthic realms with special reference to krill (Euphausiacea). We conclude that well-documented changes in the physical environment have had little effect on the fjord biota and that both organisms and their ecological functions in the fjords are well adapted to the scale of ongoing change. The observed changes fit the definition of ecosystem maturation, with greater diversity, a more complex food web and dispersed energy flow at the warmer site.

3

Can seabirds modify carbon burial in fjords?

Węsławski J. M., Urbański J., Głuchowska M., Grzelak K., Kotwicki L., Kwaśniewski S., Legeżyńska J., Wiktor J., Włodarska-Kowalczuk M., Zaborska A., Zajączkowski M., Stempniewicz L.

Oceanologia

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2017

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No. 59 (4)

603--611

EN

Two high latitude fjords of Spitsbergen (Hornsund 77°N and Kongsfjorden 79°N) are regarded as being highly productive (70 g and 50 gC m−2 year−1) and having organic-rich sediments. Hornsund has more organic matter in its sediments (8%), nearly half of it of terrestrial origin, while most of that in Kongsfjorden (5%) comes from fresh, marine sources (microplankton). Analysis of the carbon sources in both fjords shows that a major difference is the much larger seabird population in Hornsund-dominated with over 100 thousands pairs of plankton feeding little auks in Hornsund versus 2 thousand pairs in Kongsfjorden, and marine food consumption estimated as 5573 tonnes of carbon in Hornsund, versus 3047 tonnes in Kongsfjorden during one month of chick feeding period. Seabird colonies supply rich ornithogenic tundra (595 tonnes of C, as against only 266 tonnes of C in the Kongsfjorden tundra). No much of the terrestrial carbon, flushed out or wind-blown to the fjord, is consumed on the seabed – a state of affairs that is reflected by the low metabolic activity of bacteria and benthos and the lower benthic biomass in Hornsund than in Kongsfjorden.

4

Attenuation of ultraviolet irradiance in North European coastal waters

Aas E., Hojerslev N. K.

Oceanologia

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2001

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No. 43 (2)

139-168

EN

A total of 439 measurements of downward ultraviolet irradiance in North European coastal waters have been analysed, half of which have been taken from other authors. The depths Z(10%) where the irradiance is reduced to 10% of its surface value vary by one order of magnitude in the open coastal waters, both at wavelengths of 310 nm (0.3–10.4 m) and 380 nm (1.2–13.0 m). In the fjords and estuaries the depth ranges are reduced to 0.08–6.1 m at 310 nm and 0.18–7.7 m at 380 nm. Mixing with saline ocean waters can increase these light penetration depths to more than 10 m, while river water can reduce them to a few centimetres.

5

Entrapment of macroplankton in an Arctic fjord basin, Kongsfjorden, Svalbard

Węsławski J.M., Pedersen G., Petersen S. F., Poraziński K.

Oceanologia

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2000

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No. 42 (1)

57-69

EN

This paper presents the results of 15 zooplankton tows collected with a Tucker Trawl (1 m2 opening, net of 2 mm mesh size) in Kongsfjorden (79oN), Svalbard archipelago. The hydroacoustic survey revealed clear differences between the plankton concentrations in the outer and inner fjord basins. Plankton concentrations and fish were observed in the outer fjord, while uniformly scattered objects were detected in the inner basin. The macroplankton community was dominated by Euphausiacea (Thysanoessa inermis, Thysanoessa rashii), Amphipoda (Themisto libellula) and Pteropoda (Limacina helicina). Other taxa were of minor numerical importance. The macroplankton abundance reached 3300 indiv. 100-1 m-3 with a maximum biomass of 100 g wet weight 100-1 m-3 (over 440 kJ 100-1 m-3). L. helicina was advected into the fjord with surface waters, and was found in large abundance (1000 indiv. 100-1 m-3) in the subsurface layers of the inner basin. Euphausids were present in small numbers at the entrance to the fjord, but were found to be very abundant (600 indiv. 100-1 m-3) at the innermost stations, especially in the surface water layer. The estuarine circulation driven by the glacial meltwater discharge is believed to cause the entrapment of zooplankton in the inner fjord basin.