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Fatty acid (FA) composition of the blubber in free-ranging white whales (Delphinapterus leucas) from Svalbard's waters was determined and compared with the fatty acid composition of potential prey species in an attempt to assess diet. This methodology is based on the common assumption that unique arrays of FAs found within groups of organisms are transferred, largely unaltered, up marine food chains and thus may be useful for assessment of diet composition. Complete-column blubber biopsies were sampled from white whales (n=7) during the summers of 1996 and 1997. All captured animals were adult males. FAs were extracted from 2–4 replicates taken from an area about 10 cm in front of the mid-dorsal ridge. FA data from a total of 12 potential prey species from the Svalbard area were compared to the white-whale blubber samples. Twenty-two FAs were consistently found in relative amounts >0.5% of the total FA composition in white whales. These FAs accounted for 94–96% of the total FAs present. The blubber was composed almost entirely of triacylglycerols. The major saturated FAs were 14:0 and 16:0; 16:1(n-7), 18:1(n-9) and 20:1(n-9) were the major monounsaturated FAs and 20:5(n-3) and 22:6(n-3) were the major polyunsaturated FAs. Sixteen of the 22 FAs consistently found in the white-whale blubber were also found in considerable amounts (>0.5% of total FAs) in most of the potential species. Principal Component Analysis run on these 16 FAs suggests that polar cod (Boreogadus saida) had the most similar FA composition to the white-whale blubber, followed by capelin (Mallotus villosus), the copepod Calanus hyperboreus and the shrimp Pandalus borealis.

Nghiên cứu kích thước, tăng trưởng và sự khác biệt tình dục của chín đặc điểm hộp sọ đã được thực hiện trên 300 cá thể gấu Bắc Cực East Greenland và 391 cá thể gấu Bắc Cực Svalbard (Ursus maritimus). Hai đặc điểm đã lớn hơn đáng kể ở gấu từ East Greenland so với gấu Svalbard, và kích thước đặc điểm nhỏ hơn sau năm 1960 ở năm đặc điểm. Đối với cả hai địa phương và cả hai nhóm tuổi (thú vị thành niên, trưởng thành), giá trị kích thước đặc điểm trung bình cao hơn ở con đực so với con cái (tất cả: P < 0.05). Mô hình tăng trưởng Gompertz cho thấy kích thước đặc điểm tăng theo tuổi ở bảy đặc điểm. Tùy thuộc vào đặc điểm, con đực đạt 95% kích thước đặc điểm tiệm cận ở tuổi từ 3-10, con cái ở tuổi từ 2-6. Những con cái ở cả hai địa phương đều trưởng thành ở độ tuổi tương tự, trong khi con đực Svalbard thường trưởng thành muộn hơn nhiều so với bạn đồng trang lứa ở East Greenland. Những khác biệt được phát hiện trong nghiên cứu hiện tại giữa hai quần thể gấu Bắc Cực hỗ trợ quan điểm rằng gấu Bắc Cực East Greenland và Svalbard nên được quản lý như các đơn vị riêng biệt.

Although carbonic anhydrase is a ubiquitous enzyme involved in a variety of physiological processes, the information on its evolution and cold adaptation among Antarctic fish is still limited: the only Antarctic fish carbonic anhydrase characterized up-to-date is from Chionodraco hamatus, a member of the Channichthyidae family. In this work, we characterized orthologous genes within two other fish families: Nototheniidae (Trematomus eulepidotus, Trematomus lepidorhinus, Trematomus bernacchii) and Bathydraconidae (Cygnodraco mawsoni). The cDNAs of epithelial gill carbonic anhydrases were cloned and sequenced. Both coding and deduced amino acid sequences were used in phylogenetic analyses. The group of enzymes preferentially expressed in fish erythrocytes (CAIIb) represented the most conserved variant. This result suggests that, although the two variants derived from the same ancestor, CAIIc genes have a more complex evolutionary history than CAIIb. The peculiar distribution of Antarctic CAs among fish CAIIcs suggests that the CAIIc gene appeared at different times through independent duplication events, even after the speciation that led to the differentiation of Antarctic fish families. Using the new CA sequences, we built homology models to trace the expected consequences of sequence variability at the protein structure level. From these analyses, we inferred that sequence variability in Antarctic fish CAs affect important physicochemical properties of these proteins and consequentially influence their reactivity. Furthermore, we searched and tested the validity of various potential molecular trademarks for cold adaptation: significant features that can be related to cold adaptation in fish CAs include reduction of positively charged solvent accessible surfaces and an increased flexibility of N-terminal and C-terminal regions.

The undulating ice of the McMurdo Ice Shelf, Southern Victoria Land, supports one of the largest networks of ice-based, multiyear meltwater pond habitats in Antarctica, where microbial mats are abundant and contribute most of the biomass and biodiversity. We used 16S rRNA and 18S rRNA gene high-throughput sequencing to compare variance of the community structure in microbial mats within and between ponds with different salinities and pH. Proteobacteria and Cyanobacteria were the most abundant phyla, and composition at OTU level was highly specific for the meltwater ponds with strong community sorting along the salinity gradient. Our study provides the first detailed evaluation of eukaryote communities for the McMurdo Ice Shelf using the 18S rRNA gene. They were dominated by Ochrophyta, Chlorophyta and Ciliophora, consistent with previous microscopic analyses, but many OTUs belonging to less well-described heterotrophic protists from Antarctic ice shelves were also identified including Amoebozoa, Rhizaria and Labyrinthulea. Comparison of 16S and 18S rRNA gene communities showed that the Eukaryotes had lower richness and greater similarity between ponds in comparison with Bacteria and Archaea communities on the McMurdo Ice shelf. While there was a weak correlation between community dissimilarity and geographic distance, the congruity of microbial assemblages within ponds, especially for Bacteria and Archaea, implies strong habitat filtering in ice shelf meltwater pond ecosystems, especially due to salinity. These findings help to understand processes that are important in sustaining biodiversity and the impact of climate change on ice-based aquatic habitats in Antarctica.

Aerobiological studies were conducted for >1 year using arrays of rotorod samplers at three sites on Signy Island, South Orkney Islands, maritime Antarctic. Spores of five bryophyte taxa were identified, all of which are known to be widely distributed and fruit frequently on the island. Spore size did not appear to influence potential for dispersal, with spores of all five taxa being captured 0.5–1 km from their nearest known source plants. Spores were more abundant than plant fragments, although the occurrence of both propagule types in the air was small in comparison to the ground cover of mosses, and the occurrence of lichen propagules in the air. Spores were captured over a much longer period of the year (including the winter months) than that in which sporophyte dehiscence is thought to occur on Signy Island; possible reasons for this are discussed.

Mesozooplankton were sampled at shelf and oceanic stations close to South Georgia, South Atlantic during austral autumn 2004 with a Longhurst Hardy Plankton Recorder. Onshelf biomass ranged from 2.18 to 5.75 g DM m−2 (0–200 m) and was dominated by the small euphausiid Thysanöessa spp. At the oceanic stations (10.57–14.71 g DM m−2, 0–1,000 m) large calanoids, principally Rhincalanus gigas comprised ∼47–52% of biomass. Here Calanus simillimus was still active and reproducing in surface waters (0–11.2 eggs fem day−1) but R. gigas and Calanoides acutus were largely resident in the warm deep water and undergoing their seasonal descent. A comparison with spring and summer data indicated increased abundance and biomass from spring through to summer followed by a decline towards autumn particularly over the shelf. Autumn values in oceanic waters differed little from summer. Mesozooplankton biomass in the surface 200 m of the oceanic stations as a proportion of that found in the top 1,000 m ranged from 63 to 78% of the total in spring and 62–73% in summer, but was only 23–29% of the total in this study, following redistribution down the water column.

The dispersion of passerines, ptarmiganLagopus mutus and waders in relation to available snowfree patches is described after spring arrival but prior to the main thaw at Pronchishcheva Lake, north-eastern Taimyr, in June 1991. The numbers of ptarmigan and passerines were proportional to patch perimeter but disproportionately more birds occurred on smaller patches. In contrast, wader numbers were proportional to patch area but disproportionately more occurred along the perimeters of large patches. These patterns are discussed in relation to risk of predation and food availability. We speculate that the predation risk is higher in small patches for uniformly coloured birds but may be lower for white and pied species. The availability of overwintering plants, fresh plant growth and insects is thought to be highest at the perimeters of snow-free patches.

We analysed quantity and quality of particulate organic matter during the austral summer 1994/1995 at a coastal station in Terra Nova Bay (Ross Sea, Antarctica). Our main aims were to investigate the origin and biochemical composition of particulate organic matter (POM), to measure its availability for consumers through the study of its digestible fraction (measured by using different enzymes separately) and to highlight the role of hydrolizable compounds in the organic matter diagenesis in the coastal waters at Terra Nova Bay. Temporal and spatial patterns of chlorophyll-a concentrations were reflected by the particulate organic carbon, nitrogen and total biopolymeric carbon concentrations, suggesting that most POM originated directly from phytoplankton. The most evident feature of POM in the coastal waters at Terra Nova Bay was the dominance of proteins (on average 57% of total biopolymeric particulate carbon), followed by carbohydrates (25%) and lipids (18%). We found that about 30% of the refractory particulate organic carbon (assumed to be present only after the complete exploitation of particulate organic nitrogen) did not originate from biopolymeric carbon (as sum of carbohydrate, protein and lipid carbon). This allows us to suggest the use of the digestible fraction of particulate biopolymeric carbon as a more accurate measure of the food availability of POM for consumers. In Terra Nova Bay coastal waters, most of the particulate protein pool was associated with large phytoplankton cells or phytodetritus. As a result, the protein pool appeared less available (i.e. less digestible) than the one present in oligotrophic waters where, conversely, most particulate organic nitrogen is sequestered into bacteria. The relative low availability of the protein pool, together with the rapid sinking of POM and the low remineralization rates of benthic heterotrophic microbes, are suggested as possible factors in determining the “inefficiency” in organic matter recycling of coastal waters at Terra Nova Bay, which behaves as a “loss type” system.

A breeding population of black-browed albatrosses has been known to exist at the Ildefonso Archipelago, Chile, for >90 years but the population has never been censused using scientifically defendable methods. To estimate population size, and examine the accuracy and practicality of various census methods, the population was censused in the 2002/2003 breeding season using (a) ground-truthed aerial photography, (b) yacht-based photography, (c) ground counts, (d) quadrat sampling and (e) point-distance sampling. Compared to ground-truthed aerial photography (judged the most accurate) yacht-based photography underestimated population size by 55%, ground counts by 13%, quadrat sampling by 11% and point-distance sampling by 9%. Ground-truthed air photography revealed that in the 2002/2003 breeding season 47,000 pairs of black-browed albatrosses bred at the Ildefonso Archipelago. A repeat aerial census in 2006 suggested the size of the breeding population had not changed in the 4 years between the two censuses. After the Falkland Islands/Islas Malvinas, South Georgia and Diego Ramirez, the Ildefonso Archipelago holds the fourth largest population of black-browed albatrosses in the world.