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1.
Samples of ice algae from the Marginal Ice Zone in the Barents Sea could be divided into two categories: one dominated by assemblages of Melosira arctica, and the other dominated by Nitzschia frigida and associated diatoms. Total lipid from the Melosira assemblages consisted of approximately equal amounts of polar lipids and triacylglycerols. Total lipid from the Nitzschia assemblages contained more triacylglycerols than polar lipids. Total lipid from the Melosira assemblages had higher percentages of C16 PUFA, especially 16:4(n-1) and 20:5(n-3), than that from the Nitzschia assemblages, this reflecting the higher percentages of both C16 PUFA and 20:5(n-3) in polar lipids than in triacylglycerols. Phytoplankton from the pelagic zone were␣richer in flagellates and contained less C16 PUFA and 20:5(n-3) but more C18 PUFA and 22:6(n-3). The dominance of diatoms in the ice-algae assemblages in the Marginal Ice Zone and their high nutritional value as a source of 20:5(n-3) for higher trophic levels are emphasised. Received: 24 November 1997 / Accepted: 8 February 1998  相似文献   

2.
The waters around the northern tip of the Antarctic Peninsulashow complex patterns of water circulation due to mixing ofdiverse water masses. Physicochemical properties of the differentwater types should affect the distribution, biomass and speciescomposition of the phytoplankton assemblages. We examined thesefeatures in the marginal ice zone (MIZ) of the northwesternWeddell Sea. Areas with the higher biomass were located in theWeddell Sea MIZ where the surface waters were relatively stabledue to the sea-ice melting. In these waters, the colonial stageof Phaeocystis antarctica and micro-sized chain-forming diatomsaccounted for 70% of the total phytoplankton carbon. Watersin the Bransfield Strait region, in contrast, were characterizedby a dominance of nanoflagellates, which accounted for 80% ofthe total phytoplankton carbon. Our observations support thehypothesis that the species composition of phytoplankton communitiesis a function of the different water mass, reflecting the physicalconditions of the upper water column, particularly its stability.  相似文献   

3.
Summary Phytoplankton biomass and species composition were studied in transects through the ice edge region of the Greeland Sea from 19 July to 8 August 1984. Biomass was estimated by vertical in situ chlorophyll fluorescence and pigment extraction of discrete samples. Preserved material was used for identification of phytoplankton species and calculation of their relative abundances. The results suggest that the various geographical regions of the Greenland Sea differ considerably in their phytoplankton development. Autotrophic biomass and species composition were closely associated with the extent of the annual and seasonal ice cover, hydrographic conditions, nutrient availability and the water masses typical of the different domains. In the NE Greenland polynya a deep mixed layer inhibited the development of a phytoplankton bloom, whereas greatest biomass concentrations were associated with a receding ice edge on the E Greenland Shelf. In the Fram Strait, the position of the relatively stationary ice edge is controlled by frontal dynamics, currents and wind. Due to rapidly changing physical and chemical conditions, phytoplankton biomass showed great variability between stations. High chlorophyll a concentrations may develop locally where melting ice causes stratification or can result from passive accumulation in eddies. In July/August 84 the Fram Strait area was dominated by a typical summer population of flagellates and large diatom species.Contribution 6 of the Alfred-Wegener-Institute for Polar and Marine Research  相似文献   

4.
The biomass and productivity of sea ice algae was assessed in the northwestern Barents Sea in May 2004. Sea ice algal pigment content was patchy with a mean of 18.5 ± 8.9 mg Chla m−2. The algal community was dominated by the diatom Nitzschia frigida. Primary production measured by 14C incubations was between 0.37 and 2.8 mg C m−2 h−1, which compared well with oxygen-based methods using the diffusive boundary layer approach (0.071–1.1 mg C m−2 h−1). Given the differences in the irradiances under which these two sets of measurements were made, there was a strong level of consistency between the two sets of results. Measurements of primary production were consistent with previous Arctic measurements but high spatial heterogeneity made a regional estimate of production inappropriate.  相似文献   

5.
During a spring cruise to the ice-covered Barents Sea in May 1997, high concentrations of Calanus glacialis eggs were found below the pack ice. Maximum abundance was 5,900 eggs m-3 directly at the ice-water interface. Vertical distribution in the water column showed a decrease with depth, indicating positive buoyancy of the eggs. The possible role of the under-ice habitat as a nursery ground for C. glacialis is suggested.  相似文献   

6.
New data have been obtained on the spatial distribution of the early developmental stages of Malacostraca in the mesozooplankton of the southern Barents Sea. In spring 2007, the euphausiid stages with the highest abundance (over 80%) were eggs and nauplii. Decapod larvae were represented by zoeae of Paralithodes camtschaticus, Pagurus pubescens, and Hyas araneus; their abundance was at most 1.5% of total zooplankton abundance. The larvaton groups dominant by abundance were furciliae of Euphasiacea (14.5 ± 6.2 mg/m3) and zoeae of P. camtschaticus (32.7 ± 15.9 mg/m3). The size structure of larval hemipopulations was similar over the studied water area. Comparison with data on the larval body length obtained in other areas of the sea leads to a conclusion on the independence of the decapod groups of Eastern and Western Murman.  相似文献   

7.
Arctic ice amphipods are part of the sympagic macrofauna in the Marginal Ice Zone of the northern Barents Sea and represent an important link from lower to higher trophic levels in some Arctic marine food chains. The species diversity in this area (1995/1996) consisted of four species: Gammarus wilkitzkii, Apherusa glacialis, Onisimus nanseni and Onisimus glacialis. The larger ice amphipod, G. wilkitzkii, was the most abundant with the highest biomass (>90%), whereas A. glacialis was abundant, but contributed little to the total biomass (<4%). The other two species were found only in small numbers. Both abundance and biomass of ice amphipods decreased along a latitudinal gradient from north to south across the Marginal Ice Zone. Their distribution was also related to the under-ice topography with regard to mesoscale structures (edge, flat area, dome and ridge). Overall, the abundance and biomass on ridges were much higher in comparison to other mesoscale structures, although edges also showed high abundance, but low biomass. The large G. wilkitzkii was consistently abundant on ridges. The small A. glacialis was predominately associated with edges, but also showed high numbers in dome-shaped areas. The Onisimus species were present in low numbers at all structures, and their biomass contributed <10% on any one structure. The reasons for different distribution patterns of the dominant amphipod species under Arctic sea ice are probably related to different requirements of the species, especially for food, shelter and physiological conditions. Accepted: 27 November 1999  相似文献   

8.
9.
During spring 1986 and winter 1987, zooplankton samples were collected over the entire North Sea by means of a multi-closing net-system. Before taxonomic treatment, wet weight estimates and carbon content conversions were carried out. From this data set, 4 962 522 tons zooplankton biomass (dry weight) were estimated for the whole North Sea during the spring survey. High biomasses (more than 100 mg C/m3) were located in areas between the Orkneys and the Shetlands, off the mouth of the Firth of Forth, the Channel and the river Rhine. Considerable zooplankton biomass was also found parallel to the Danish west coast. Furthermore, a narrow tongue of high biomass (partly greater than 200 mg C/m3) intruded from the north, between 1 °E and 4 °E, into the northern North Sea, turning to the east at 56°N, and continuing into deeper water layers to form a left turning “helix” of high biomass in the central part of the North Sea. During the winter survey the carbon content of the zooplankton stock was a factor 10 lower than in summer. Altogether, 519340 tons of zooplankton biomass (dry weight) were estimated in winter. Centres of relatively high biomass were located off the mouth of the rivers Rhine, Weser and Elbe and off the British east coast moving in a cyclic way across the Dogger Bank into the central North Sea. A further maximum of zooplankton abundance was found in the Skagerrak region. However, an intrusion of zooplankton from the shelf edge into the North Sea was not observed in winter. A qualitative analysis of species composition showed that small copepods dominated the zooplankton in the southern and eastern North Sea. The “eddy” of high biomass in the northern North Sea observed in spring, however, was mostly shaped by the large copepodCalanus finmarchicus (70–90%). The distribution of zooplankton biomass in the North Sea is discussed in relation to the hydrographic conditions and to the biology of the dominant species.  相似文献   

10.
We present a list of zooplankton taxa occurring in the Barents Sea based on our analysis of 360 samples from the upper 100 m of the water column as well as on reports from published sources. Moreover, we provide information on adult size, ecological and geographical distribution, habitat preference and frequency of occurrence of each taxon. The list encompasses a total of 374 species and higher taxa. Most are mesozooplankton, with Copepoda prevailing (153 species), and belong to the holoplankton. However, pseudoplankton, organisms only circumstantially occurring in the water column, also comprise a significant part of the fauna (86 taxa). The coastal zooplankton (264 neritic species) was richer than the fauna of the open sea. In our samples, the majority of the zooplankton taxa were rarely found (94 of 157 taxa, equivalent of 60%), 46 taxa (29%) were moderate and only 17 taxa (11%) were common (found in >80% of the samples). Among these, the copepods Calanus finmarchicus, C. glacialis, Oithona similis and Pseudocalanus minutus were most frequent.  相似文献   

11.
Russian Journal of Marine Biology - This article presents the results of studies of the cyanobacteria from foulings of natural and anthropogenic substrates of the intertidal zone of the Kola Bay of...  相似文献   

12.
Enzymatic preparations from king crab hepatopancreas were shown to be capable, in principle, of producing protein hydrolysates. Hydrolysis of protein-containing waste of deep-water prawn and king crab occurs most successfully at pH 8.0-8.5 and 50-55 degrees C for 5-6 h in the presence of 6 g enzyme per kg substrate. The total chemical composition of the hydrolysates, the molecular weight distributions of proteins and polypeptides, and the contents of free amino acids were studied in dry hydrolysates.  相似文献   

13.
Enzymatic Hydrolysis of Proteins from Crustaceans of the Barents Sea   总被引:1,自引:0,他引:1  
Enzymatic preparations from king crab hepatopancreas were shown to be capable, in principle, of producing protein hydrolysates. Hydrolysis of protein-containing waste of deep-water prawn and king crab occurs most successfully at pH 8.0–8.5 and 50–55°C for 5–6 h in the presence of 6 g enzyme per kg substrate. The total chemical composition of the hydrolysates, the molecular weight distributions of proteins and polypeptides, and the contents of free amino acids were studied in dry hydrolysates.  相似文献   

14.
15.
The total population density and the biomass of bacterioplankton, mesozooplankton, and phosphate-accumulating bacteria (PAB) were estimated during the 2000-2001 summer-autumn seasons in the coastal waters of the White and Barents Seas, which are subjects to the action of tidal and sea currents, the inflow of riverine waters, and anthropogenic impact. In the shallow estuarine waters with salinities of 6.5-32@1000 near the Chernaya, Pesha, and Pechora River mouths, the population of PAB fluctuated from 0.1 to 9.1 million cells/ml (0-36% of the total bacterial population). In pelagic seawaters, which are low in phosphates (12-50 micrograms/l) and are characterized by an increased iron/phosphorus ratio (2.0-3.6), bacterioplankton amounted to 0.1-1.6 million cells/ml and was mainly represented by small organisms with a volume of 0.08-0.15 micron 3, commonly lacking intracellular polyphosphates. In the pelagic zone of the Barents Sea, the biomass of mesozooplankton (Bz) was comparable with that of bacterioplankton (Bb = 39-175 mg/m3), the Bb/Bz ratio being 1.4-4.6. Off the Varandeiskii, Pechora, and Kolguyev oil terminals, Bb increased to 155-300 mg/m3 and the Bb/Bz ratio rose to 1.4 to 50.3 (with an average value of 20.9), presumably due to the severe anthropogenic impact on these waters. In this case, the dense population of bacterioplankton (0.9-7.6 million cells/ml) was mainly represented by large cells (0.12-0.76 micron 3 in volume), most of which (3-43% of the total bacterioplankton population) contained polyphosphates. The chemical composition of these waters was characterized by an elevated content of the total phosphorus (65-128 micrograms/l) and by a low iron/phosphorus ratio (0.9-1.2).  相似文献   

16.
During a visit to Norway by the Russian president in the spring of 2010, the president and the Norwegian prime minister surprisingly announced agreement on a delimitation line in the Barents Sea ending almost 40 years of negotiations. The agreement was signed in Murmansk on 15 September 2010. This article presents the background of the dispute and undertakes an assessment of the agreement and its implications for the Barents Sea, Svalbard, and other Arctic maritime delimitations.  相似文献   

17.
Algal communities and export of organic matter from sea ice were studied in the offshore marginal ice zone (MIZ) of the northern Barents Sea and Nansen Basin of the Arctic Ocean north of Svalbard by means of ice cores and short-term deployed sediment traps. The observations cover a total of ten stations within the drifting pack ice, visited over a period of 3 years during the period of ice melt in May and July. Maximum flux of particulate organic carbon and chlorophyll a from the ice at 1 m depth (1,537 mg C m−2 per day and 20 mg Chl a m−2 per day) exceeded the flux at 30 m by a factor of 2 during spring, a pattern that was reversed later in the season. Although diatoms dominated the ice-associated algal biomass, flagellates at times revealed similarly high biomass and typically dominated the exported algal carbon. Importance of flagellates to the vertical flux increased as melting progressed, whereas diatoms made the highest contribution during the early melting stage. High export of ice-derived organic matter and phytoplankton took place simultaneously in the offshore MIZ, likely as a consequence of ice drift dynamics and the mosaic structure of ice-covered and open water characteristic of this region.  相似文献   

18.
Summary Variations in under-ice scalar irradiance, P vs I parameters and the CHLa C–1 ratio of natural assemblages of sea-ice microalgae from the Barents Sea growing at -1.8°C in May and September 1988 are described, including one diurnal station. CHLa C–1 ratios of 0.031–0.071 mg mg–1 indicate shade adaptated assemblages both in May and September. Values for B (photosynthetic efficiency) were generally low, e.g. 0.0025–0.0078 mg C (mg CHLa)–1 h–1 (mol m–2 s–1)–1, and should be typical for self-shaded algae in mats or aggregates of about 4 mm thickness. Provided no self shading and the typical spectral distribution of light under ice without algae, B would, however, be about 2.5 times higher. Photoinhibition of the photosynthetic response was negligible. Maximum carbon uptake P m B was 0.15–0.24 and 0.032–0.088 mg C (mg CHLa)–1 h–1 in May and September, respectively. Diurnal variations were small, particularly for P m B . Calculations of the maximum specific gross growth rate yielded an upper limit of 0.20–0.24 and 0.01–0.04 d–1 for assemblages in May and September, respectively; the latter may have been in a resting stage.Contribution No. 245, Trondhjem Biological Station  相似文献   

19.
20.
The paper deals with the microbiological characterization of water-saturated horizons in permafrost soils (cryopegs) found on the Varandei Peninsula (Barents Sea coast), 4-20 m deep. The total quantity of bacteria in the water of cryopegs was 3.5 x 10(8) cells/ml. The population of cultivated aerobic heterotrophic bacteria was 3-4 x 10(7) cells/ml and the number of anaerobic heterotrophic bacteria varied from 10(2) to 10(5) cells/ml depending on cultivation temperature and salinity. Sulfate-reducing bacteria and methanogenic archaea were found as hundreds and tens of cells per ml of water, respectively. A pure culture of a sulfate-reducing strain B15 was isolated from borehole 21 and characterized. Phylogenetic analysis has shown that the new bacterium is a member of the genus Desulfovibrio with Desulfovibrio mexicanus as its closest relative (96.5% similarity). However, the significant phenotypic differences suggest that strain B15 is a new species of sulfate-reducing bacteria.  相似文献   

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