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  • 1
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sympagic (=ice-associated) amphipod Gammarus wilkitzkii usually lives attached to the underside of Arctic sea ice. During an expedition to the Greenland Sea in May/June 1997, high numbers of this species were found in pelagic Rectangular Midwater Trawl catches (0–500 m water depth) in an ice-free area, 35–42 km away from the ice edge. The amphipods seemed to have maintained position in the water column for at least 4 days. Mean biomass data (length: 2.9 cm, organic content: 73% dry mass), gut fullness (〉50% in 85% of specimens) and sex ratio (females:males = 1:1.5) of these amphipods were very similar to values for under-ice populations. Due to their relatively high body density (mean: 1.134 g cm−3), the energy demand for swimming was assumed to be high. Measurements of oxygen consumption of swimming and resting amphipods (8.8 and 4.0 J g wet mass−1 day−1, respectively) suggested that, from an energetic point of view, G. wilkitzkii would maintain position in an ice-free water column for the time period.
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  • 2
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lipid and fatty acid compositions of five notothenioid fishes from the Antarctic Weddell and Lazarev Seas were investigated in detail with regard to their different modes of life. The pelagic Aethotaxis mitopteryx was the lipid-richest species (mean of 61.4% of dry mass, DM) followed by Pleuragramma antarcticum (37.7%DM). The benthopelagic Trematomus lepidorhinus had an intermediate lipid content of 23.2%DM. The benthic Bathydraco marri (20.8%DM) and Dolloidraco longedorsalis (14.5%DM) belonged to the lipid-poorer species. Triacylglycerols were the major lipid class in all species. Important fatty acids were 16:0, 16:1(n-7), 18:1(n-9), 18:1(n-7), 20:5(n-3) and 22:6(n-3). The enhanced proportions of the long-chain monounsaturated fatty acids, 20:1 and 22:1, in the lipid-rich pelagic fishes clearly reflected the ingestion of the two copepod species, Calanoides acutus and Calanus propinquus, which are the only known Antarctic zooplankters rich in these fatty acids. Although wax esters are the major storage lipid in many prey species, they were absent in all notothenioid fishes studied. Thus, wax esters ingested with prey are probably converted to triacylglycerols via fatty acids or metabolised by the fishes. The enhanced lipid accumulation with increasingly pelagic lifestyle has energetic advantages, especially with regard to improved buoyancy. It is still unknown to what extent these lipids are utilised as energy reserves, since it has been suggested that not only the benthic but also the pelagic Antarctic fishes are rather sluggish, with a low scope for activity and hence low metabolic requirements.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Polar biology 5 (1986), S. 181-183 
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new bathypelagic species of the genus Heterokrohnia, H. longicaudata, is described and separated from the other five previously described Heterokrohnia species, H. mirabilis Ritter-Záhony 1911, H. bathybia Marumo and Kitou 1966, H. involucrum Dawson 1968, H. longidentata Kapp and Hagen 1985 and H. fragilis Kapp and Hagen 1985. The new specimen has been found at great depths (2,350m–1,000m) near Elephant Island, in the atlantic sector north of the Antarctic Peninsula.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Lung 58 (1924), S. 481-487 
    ISSN: 1432-1750
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Polar biology 4 (1985), S. 53-59 
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two new species of the genus Heterokrohnia, H. longidentata and H. fragilis, are described and compared with the other three known Heterokrohnia species, H. mirabilis Ritter-Záhony 1911; H. bathybia Marumo and Kitou 1966 and H. involucrum Dawson 1968. The species have been found at great depths (1,000 m–2,000 m) near Elephant Island, north of the Antarctic Peninsula.
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  • 6
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comprehensive data are presented on the total lipid contents of five species of notothenioid fish collected during summer 1991 in the Weddell Sea and the Lazarev Sea south of 69°S. The species were selected based on their different modes of life, benthic, benthopelagic and pelagic, to examine how the life style — among other factors — affects the proximate composition of these high-Antarctic fishes. Lipid contents of whole specimens showed an extremely wide range from 3.1 to 67.5% of dry weight (%DW), with corresponding carbon/nitrogen (C/N) ratios between 3.4 and 11.3. Lowest lipid contents were found in the benthic species Bathydraco marri and Dolloidraco longedorsalis with means of 11.0 and 11.9 %DW. The benthopelagic Trematomus lepidorhinus had an intermediate mean lipid content of 20.8 %DW, and the pelagic species Pleuragramma antarcticum and Aethotaxis mitopteryx were richest in lipid with means of 47.0 %DW and 60.8 %DW. There was a pronounced ontogenetic lipid accumulation with increasing size discernible in the lipid-rich species, especially in P. antarcticum. No clear relationship was found between lipid content and sex or maturity in A. mitopteryx and T. lepidorhinus, only the males of B. marri had higher lipid contents than the females. Lipid contents and water contents were inversely correlated. In conclusion, the mode of life of these species was clearly reflected by their lipid contents and lipids seem to have an important function, particularly as buoyancy aids in the pelagic species, which like all notothenioids lack a swim-bladder.
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  • 7
    Publication Date: 2018-02-27
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 8
    Publication Date: 2017-07-11
    Description: The crabeater seal (Lobodon carcinophaga) is the most abundant Antarctic seal and inhabits the circumpolar pack ice zone of the Southern Ocean. Until now, information on important environmental factors affecting its distribution as well as on foraging behaviour is limited. In austral summer 1998, 12 crabeater seals of both sexes and different age classes were equipped with satellite-linked dive recorders at Drescher Inlet (72.85°S, 19.26°E), eastern Weddell Sea. To identify suitable habitat conditions within the Weddell Sea, a maximum entropy (Maxent) modelling approach was implemented. The model revealed that the eastern and southern Weddell Sea is especially suitable for crabeater seals. Distance to the continental shelf break and sea ice concentration were the two most important parameters in modelling species distribution throughout the study period. Model predictions demonstrated that crabeater seals showed a dynamic response to their seasonally changing environment emphasized by the favoured sea ice conditions. Crabeater seals utilized ice-free waters substantially, which is potentially explained by the comparatively low sea ice cover of the Weddell Sea during summer 1998. Diving behaviour was characterized by short (〉90 % = 0–4 min) and shallow (〉90 % = 0–51 m) dives. This pattern reflects the typical summer and autumn foraging behaviour of crabeater seals. Both the distribution and foraging behaviour corresponded well with the life history of the Antarctic krill (Euphausia superba), the preferred prey of crabeater seals. In general, predicted suitable habitat conditions were congruent with probable habitats of krill, which emphasizes the strong dependence on their primary prey.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    Springer
    In:  EPIC3Handbook on Marine Environment Protection, Cham, Switzerland, Springer, 21 p., pp. 353-373, ISBN: 978-3-319-60156-4
    Publication Date: 2018-02-09
    Description: In this chapter, the effects of temperature change—as a main aspect of climate change—on marine biodiversity are assessed. Starting from a general discussion of species responses to temperature, the chapter presents how species respond to warming. These responses comprise adaptation and phenotypic plasticity as well as range shifts. The observed range shifts show more rapid shifts at the poleward range edge than at the equator-near edge, which probably reflects more rapid immigration than extinction in a warming world. A third avenue of changing biodiversity is change in species interactions, which can be altered by temporal and spatial shifts in interacting species. We then compare the potential changes in biodiversity to actual trends recently addressed in empirical synthesis work on local marine biodiversity, which lead to conceptual issues in quantifying the degree of biodiversity change. Finally we assess how climate change impacts the protection of marine environments.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 10
    Publication Date: 2015-03-05
    Description: Adult Euphausia superba survive winter without or with little feeding. It is not exactly known whether the scarcity of food or an internal clock, set by the natural Antarctic light regime, are responsible for non-feeding. Our research questions were therefore the following: (1) How will physiological and biochemical conditions of krill change during long-term starvation at constant light regime? (2) If and how do enzyme activities change during such starvation? (3) What is the influence of food availability versus that of light regime? To answer these questions, adult krill were starved under laboratory conditions for 12 weeks with constant light regime (12:12; dark/light) and the impact on physiological functions was studied. Initial experimental condition of krill resembled the condition of late spring krill in the field with fully active metabolism and low lipid reserves. Metabolic activity and activities of enzymes catabolising lipids decreased after the onset of starvation and remained low throughout, whereas lipid reserves declined and lipid composition changed. Mass and size of krill decreased while the inter-moult period increased. Depletion of storage- and structural metabolites occurred in the order of depot lipids and glycogen reserves after onset of starvation until proteins were almost exclusively used after 6–7 weeks of starvation. Results confirmed various proposed overwintering mechanisms such as metabolic slowdown, slow growth or shrinkage and use of lipid reserves. However, these changes were set in motion by food shortage only, i.e.without the trigger of a changing light regime.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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