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  • Springer  (3)
  • Inter Research  (1)
  • SPRINGER HEIDELBERG  (1)
  • 2015-2019  (3)
  • 2000-2004  (2)
  • 1
    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.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-02-01
    Description: We conducted a year-round mesozooplankton study in the Arctic Kongsfjord from August 1998 until July 1999 to investigate seasonal abundance and vertical as well as stage distributions of the prevalent taxa. It is the first investigation in Kongsfjord that covers the Arctic winter season and provides reasonable estimates also of small-sized copepod species. Abundant smaller copepods comprised Oithona similis, Pseudocalanus minutus, Microcalanus spp., Triconia borealis and Acartia longiremis. Among the larger copepods, Calanus finmarchicus, C. glacialis, C. hyperboreus and Metridia longa dominated. The thecosome pteropod Limacina helicina was also an important component. Abundance maxima occurred in November (988,669 ind. m−2) with one to two orders of magnitude higher numbers as compared to all other months (39,832–200,067 ind. m−2). The summers of 1998 and 1999 were characterized by intrusions of Atlantic water, but the community was not entirely dominated by advected boreal species. During winter, the majority of the mesozooplankton occurred below 100 m. Advection is the most likely reason for the accumulation of zooplankton at depth in winter, but local production may also contribute to high overwintering numbers. Much lower abundances of most species in spring suggest high winter mortality and emphasize the importance of sufficient reproductive success during the previous summer to ensure enough winter survivors as seed stock for the coming reproductive season. This study was conducted prior to the recent warming trend in the Arctic. Therefore, it provides valuable baseline data and allows comparing present and future states of the zooplankton community in Kongsfjord.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2018-05-28
    Description: Zooplankton grazing on bacterio- and phytoplankton was studied in the Gulf of Aqaba and the Northern Red Sea during Meteor Cruise Me 44-2 in February-March 1999. Protozoan grazing on bacterioplankton and autotrophic ultraplankton was studied by the Landry dilution method. Microzooplankton grazing on phytoplankton 〉6 µm was studied by incubation experiments in the presence and absence of microzooplankton. Mesozooplankton grazing was studied by measuring per capita clearance rates of individual zooplankton with radioactively labelled food organisms and estimating in situ rates from abundance values. Protozoan grazing rates on heterotrophic bacteria and on algae 〈6 µm were high (bacteria: 0.7 to 1.1 d-1, ultraphytoplankton: 0.7 to 1.3 d-1), while grazing rates on Synechococcus spp. were surprisingly low and undetectable in some experiments. Mesozooplankton grazing was weak, cumulative grazing rates being ca. 2 orders of magnitude smaller than the grazing rates by protozoans. Among mesozooplankton, appendicularians specialised on smaller food items and calanoid copepods on larger ones.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2019-10-04
    Description: Hyperiidean amphipods are a major prey for fish and seabirds. In the Southern Ocean, they are particularly abundant, with distributions ranging from the Polar Frontal Zone to Antarctic shelf waters. The species Hyperiella dilatata has previously been reported to show a peculiar anti-predatory behaviour: It captures chemically protected, gymnosome pteropods in the water column and carries them on its dorsum, like a backpack. We report this association at four oceanic sampling sites between latitudes 45° and 71° S. Molecular barcodes of both hosts and pteropods are provided and compared with those of other hyperiidean and pteropod specimens. Morphological identifications as well as molecular analyses show a so far undocumented association of Hyperiella antarctica with the pteropod Spongiobranchaea australis in the Polar Frontal Zone (Lazarev Sea). H. dilatata carried Clione limacina antarctica specimens in the Weddell Sea, as recorded previously for the Ross Sea. Lengths of the abducted pteropods varied between 1 and 5 mm, with the biggest pteropod measuring more than half the host’s size. One of the abducting amphipods was a female carrying eggs. The formation of such tandem is known to be very efficient as protection from visually hunting icefish in the crystal-clear coastal waters around the Antarctic continent; however, in the open ocean, this behaviour was so far undocumented. Here, we develop hypotheses on its origin and function.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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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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