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Number of results: 5
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Abstract

The presence of 31 species of birds was observed at sea sout of 50°S, out of this number 26 species were present also south of 60°S. The most numerous aggregations of birds were recorded in the regions of: Elephant Island, the South Orkneys and NE part of Bransfield Strait. The average number of birds during 10-minute observation was 74.5. In the areas under observations Daption capense predominated quantitatively. The following species were subdominant: Pygoscelidae, Oceanites oceanicus, Diomedea melanophris, Fulmarus glacialoides and Macronectes giganieus. In the total number of the birds observed krill-eaters contributed in 80.1% plankton-eaters — 7.8%, squid-eaters — 6.2% omnivores — 5.9% and fish-eaters — 0.1%. In comparison with the autumnal observations more than twice as many birds at sea were observed in the same area.
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Abstract

In November 1994 a first inventory of Tanaidacea from the Beagle Channel and at some stations of the Atlantic continental shelfwas obtained using epibenthic sledge samples. In total, 2175 specimens from 27 species of eight families of Tanaidomorpha and two families of Apseudomorpha were collected. Two species, Allotanais hirstutus (Beddard, 1886) and Apseudes heroae Sieg, 1986, strongly dominated this area. Generally low diversity and abundances were recorded for the western area of the Beagle Channel, while substantially higher values were reported at the eastern entrance on the Atlantic side of the Beagle Channel. Abundances slightly varied with depths, but not significantly.
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Abstract

Herve Cove, a small, shallow and partly isolated basin, is strongly influenced by glacial freshwater inlfow, bringing significant amount of mineral suspension. Its mean annual content amounted up to 46 mg dm-3. Sea anemone (Edwardsia sp.), bivalves (Yoldia eightsi, Laternula elliptica and Mysella sp.), amphipods (mostly Cheirimedon femoratus) a well as some species of polychaetes constituted almost 95% of zoobenthos biomass and 90% of abundance. Four different assemblages of benthic invertebrates, with total biomass ranging from 0.002 kg m-2 up to 1.7 kg m-2, were distinguished in this relatively small (about 12 ha) area. It seems that the freshwater impact influences the composition of an assemblage occurring close to the edge of a glacier. Relatively rich crustacean fauna was encountered in the shallow part of the cove near its entrance. Almost complete lack of echinoderms in Herve Cove, that are common in the shallow Antarctic sublittoral, should also be noted. Macrozooplankton of Herve Cove was dominated by Copepoda. The most frequent and abundant species were: Oithona similis, Ctenocalanus citer and Metridia gerlachei. Far less numerous Chaetognatha represented by three species, Ostracoda, Polychaeta, Pteropoda and Siphonophora constituted only 2.5% of all planktonie animals collected.
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Abstract

Zooplankton community composition, abundance and biomass from two polar localities – Kongsfjorden (Arctic) and Admiralty Bay (Antarctic) is compared. The community composition of zooplankton in both polar regions included similar taxonomic groups and the diversity at the species level was similar. Even though the overall species composition was different, some species were common for both ecosystems, for example Oithona similis, Microcalanus pygmaeus or Eukrohnia hamata. The abundance and biomass of the main zooplankton components (Copepoda) differed greatly between the two ecosystems, both being of an order of magnitude higher in Kongsfjorden than in Admiralty Bay. Kongsfjorden is situated at the border of two regions what induces high productivity with copepods playing an important role, and there is also a strong advection into the fjord. Admiralty Bay is adjacent to the homogenous Antarctic oceanic ecosystem; some advection into the bay occurs as an effect of tide and wind driven processes. Antarctic krill, which was not included in the present study, occupies most of the primary consumers niche and replaces copepods at the second trophic level.
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Abstract

During a midwinter cruise north of 80oN to Rijpfjorden, Svalbard, the composition and vertical distribution of the zooplankton community were studied using two different samplers 1) a vertically hauled multiple plankton sampler (MPS; mouth area 0.25 m2, mesh size 200 μm) and 2) a horizontally towed Methot Isaacs Kidd trawl (MIK; mouth area 3.14 m2, mesh size 1500 μm). Our results revealed substantially higher species diversity (49 taxa) than if a single sampler (MPS: 38 taxa, MIK: 28) had been used. The youngest stage present (CIII) of Calanus spp. (including C. finmarchicus and C. glacialis) was sampled exclusively by the MPS, and the frequency of CIV copepodites in MPS was double that than in MIK samples. In contrast, catches of the CV-CVI copepodites of Calanus spp. were substantially higher in the MIK samples (3-fold and 5-fold higher for adult males and females, respectively). The MIK sampling clearly showed that the highest abundances of all three Thysanoessa spp. were in the upper layers, although there was a tendency for the larger-sized euphausiids to occur deeper. Consistent patterns for the vertical distributions of the large zooplankters (e.g. ctenophores, euphausiids) collected by the MPS and MIK samplers provided more complete data on their abundances and sizes than obtained by the single net. Possible mechanisms contributing to the observed patterns of distribution, e.g. high abundances of both Calanus spp. and their predators (ctenophores and chaetognaths) in the upper water layers during midwinter are discussed.
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