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  • 2020-2024  (7)
  • 2000-2004  (2)
  • 1995-1999  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Green krill, the indicator of micro- and nano-size phytoplankton availability to krill (1999)
    Springer
    Polar biology 22 (1999), S. 133-136 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Size-fractionated chlorophyll-a concentrations of surface seawater were measured for pico-, nano-, and micro-size fractions (〈2 μm, 2–10 μm, and 〉10 μm respectively) during commercial krill fishery operations in the waters north of the South Shetland Islands. The proportion of green krill (individuals discoloured due to active feeding on phytoplankton) had significant regressions with chlorophyll-a concentrations in micro- and nano-size fractions. Between these two fractions, chlorophyll-a concentration in the micro-size fraction showed the higher partial regression coefficient. This result shows the importance of phytoplankton larger than nano-phytoplankton, especially micro-phytoplankton, in terms of a phytoplanktonic food source for Antarctic krill in the natural environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050400
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Antarctic krill (Euphausia superba dana) eat salps (1996)
    Springer
    Polar biology 16 (1996), S. 479-481 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding behaviour of Antarctic krill (Euphausia superba) on salps was observed in shipboard experiments during the 1994/1995Kaiyo Maru Antarctic Ocean research cruise. The feeding rate was more than 0.5 salp/krill per day. When offered ethanol extracts of four prey types, salps, phytoplankton, krill and polychaetes, krill preferred the salp extracts. This evidence implies that the substances extracted from salps were most attractive to krill. These results might indicate a tight ecological relationship between krill and salps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02329066
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Microzooplankton grazing in the surface water of the Southern Ocean during an austral summer (1997)
    Springer
    Polar biology 18 (1997), S. 240-245 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microzooplankton grazing was investigated in surface waters of the Indo-Pacific and Atlantic sectors of the Southern Ocean by the dilution method. Phytoplankton growth varied mainly between 0.1 and 0.4 day−1, and microzooplankton grazing between 0.0 and 0.3 day−1. Great fluctuations in phytoplankton growth rate were observed at one station within 3 weeks and between closely spaced stations. Microzooplankton grazing rates were similar to phytoplankton growth rate despite the variation of phytoplankton growth rates, although in some cases, phytoplankton growth overwhelmed microzooplankton grazing. These observations suggest that microzooplankton are the main consumers of primary producers, and that steady state between phytoplankton growth and microzooplankton grazing is usually established in the Southern Ocean in austral summer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050184
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  • 4
    Electronic Resource
    Electronic Resource
    Discovery of ciliates reproducing in the gut of Antarctic krill (1997)
    Springer
    Polar biology 18 (1997), S. 158-160 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During a recent Antarctic research cruise (December 1994/February 1995), dissection of fresh Antarctic krill (Euphausia superba) on board ship revealed live motile ciliates in the gut of krill. Further observation of gut samples by scanning electron microscopy indicated that the ciliates were symbionts located within the gut. We inferred that the ciliates may have enabled the krill to digest a wider range of food items, and as a consequence, this had became an important strategy for Antarctic krill's survival in the Antarctic ecosystem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050171
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  • 5
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    Antarctic marine life under pressure (2022)
    American Association for the Advancement of Science (AAAS)
    In:  EPIC3Science, American Association for the Advancement of Science (AAAS), 378(6617), pp. 230-230, ISSN: 0036-8075
    Details
    Publication Date: 2023-05-10
    Description: 〈jats:p〉 Next week, the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) convenes in Hobart, Tasmania, to examine the state of marine life in the Southern Ocean. As part of the Antarctic Treaty System, this convention entered into force in 1982, and its focus on the region’s environmental integrity has never been more important, given the increasing effects of climate change and commercial fishing. An important focus over the past 40 years has been Antarctic krill, 〈jats:italic〉Euphausia superba〈/jats:italic〉 (hereafter krill), a keystone species that helps to hold this marine ecosystem together. Climate and fishing stresses should prompt the CCAMLR to address whether management of krill fishing is at a level that protects the Southern Ocean from losing its overall balance of marine life and the oceanic processes that regulate global climate. 〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
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    Circadian regulation of diel vertical migration (DVM) and metabolism in Antarctic krill Euphausia superba (2020)
    Springer Science and Business Media LLC
    In:  EPIC3Scientific Reports, Springer Science and Business Media LLC, 10(1), pp. 16796-16796, ISSN: 2045-2322
    Details
    Publication Date: 2023-05-10
    Description: Antarctic krill (Euphausia superba) are high latitude pelagic organisms which play a key ecological role in the ecosystem of the Southern Ocean. To synchronize their daily and seasonal life-traits with their highly rhythmic environment, krill rely on the implementation of rhythmic strategies which might be regulated by a circadian clock. A recent analysis of krill circadian transcriptome revealed that their clock might be characterized by an endogenous free-running period of about 12–15 h. Using krill exposed to simulated light/dark cycles (LD) and constant darkness (DD), we investigated the circadian regulation of krill diel vertical migration (DVM) and oxygen consumption, together with daily patterns of clock gene expression in brain and eyestalk tissue. In LD, we found clear 24 h rhythms of DVM and oxygen consumption, suggesting a synchronization with photoperiod. In DD, the DVM rhythm shifted to a 12 h period, while the peak of oxygen consumption displayed a temporal advance during the subjective light phase. This suggested that in free-running conditions the periodicity of these clock-regulated output functions might reflect the shortening of the endogenous period observed at the transcriptional level. Moreover, differences in the expression patterns of clock gene in brain and eyestalk, in LD and DD, suggested the presence in krill of a multiple oscillator system. Evidence of short periodicities in krill behavior and physiology further supports the hypothesis that a short endogenous period might represent a circadian adaption to cope with extreme seasonal photoperiodic variability at high latitude.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
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    The enormous repetitive Antarctic krill genome reveals environmental adaptations and population insights (2023)
    Elsevier BV
    In:  EPIC3Cell, Elsevier BV, 186(6), pp. 1279-1294.e19, ISSN: 0092-8674
    Details
    Publication Date: 2023-05-10
    Description: Antarctic krill (Euphausia superba) is Earth’smost abundant wild animal, and its enormous biomass is vital to the Southern Ocean ecosystem. Here, we report a 48.01-Gb chromosome-level Antarctic krill genome, whose large genome size appears to have resulted from inter-genic transposable element expansions. Our assembly reveals the molecular architecture of the Antarctic krill circadian clock and uncovers expanded gene families associated with molting and energy metabolism, providing insights into adaptations to the cold and highly seasonal Antarctic environment. Population-level genome re-sequencing from four geographical sites around the Antarctic continent reveals no clear population structure but highlights natural selection associated with environmental variables. An apparent drastic reduction in krill population size 10 mya and a subsequent rebound 100 thousand years ago coincides with climate change events. Our findings uncover the genomic basis of Antarctic krill adaptations to the Southern Ocean and provide valuable resources for future Antarctic research.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    Climate change impacts on Antarctic krill behaviour and population dynamics (2023)
    Springer Science and Business Media LLC
    In:  EPIC3Nature Reviews Earth & Environment, Springer Science and Business Media LLC, ISSN: 2662-138X
    Details
    Publication Date: 2024-01-08
    Description: Krill habitats in the Southern Ocean are impacted by changing climate conditions, reduced sea ice and rising temperatures. These changes, in turn, affect krill occurrence, physiology and behaviour, which could have ecosystem impacts. In this Review, we examine climate change impacts on Antarctic krill and the potential implications for the Southern Ocean ecosystem. Since the 1970s, there have been apparent reductions in adult population density and the occurrence of very dense swarms in the northern Southwest Atlantic. These changes were associated with latitudinal and longitudinal rearrangement of population distribution — including a poleward contraction in the Southwest Atlantic — and were likely driven by ocean warming, sea-ice reductions and changes in the quality of larval habitats. As swarms are targeted by fishers and predators, this contraction could increase fishery–predator interactions, potentially exacerbating risk to already declining penguin populations and recovering whale populations. These risks require urgent mitigation measures to be developed. A circumpolar monitoring network using emerging technologies is needed to augment existing surveys and better record the shifts in krill distribution.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    No distinct local cuisines among humpback whales: A population diet comparison in the Southern Hemisphere (2024)
    Elsevier
    In:  EPIC3The Science of The Total Environment, Elsevier, 931, pp. 172939-172939, ISSN: 0048-9697
    Details
    Publication Date: 2024-06-13
    Description: Southern hemisphere humpback whale (Megaptera novaeangliae, SHHW) breeding populations follow a high-fidelity Antarctic krill (Euphausia superba) diet while feeding in distinct sectors of the Southern Ocean. Their capital breeding life history requires predictable ecosystem productivity to fuel migration and migration-related behaviours. It is therefore postulated that populations feeding in areas subject to the strongest climate change impacts are more likely to show the first signs of a departure from a high-fidelity krill diet. We tested this hypothesis by investigating blubber fatty acid profiles and skin stable isotopes obtained from five SHHW populations in 2019, and comparing them to Antarctic krill stable isotopes sampled in three SHHW feeding areas in the Southern Ocean in 2019. Fatty acid profiles and δ13C and δ15N varied significantly among all five populations, however, calculated trophic positions did not (2.7 to 3.1). Similarly, fatty acid ratios, 16:1ω7c/16:0 and 20:5ω3/22:6ω3 were above 1, showing that whales from all five populations are secondary heterotrophs following an omnivorous diet with a diatom-origin. Thus, evidence for a potential departure from a high-fidelity Antarctic krill diet was not seen in any population. δ13C of all populations were similar to δ13C of krill sampled in productive upwelling areas or the marginal sea-ice zone. Consistency in trophic position and diet origin but significant fatty acid and stable isotope differences demonstrate that the observed variability arises at lower trophic levels. Our results indicate that, at present, there is no evidence of a divergence from a high-fidelity krill diet. Nevertheless, the characteristic isotopic signal of whales feeding in productive upwelling areas, or in the marginal sea-ice zone, implies that future cryosphere reductions could impact their feeding ecology.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 10
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    Antarctic krill (Euphausia superba dana) eat salps (1996)
    Springer
    Details
    Publication Date: 1996-08-01
    Print ISSN: 0722-4060
    Electronic ISSN: 1432-2056
    Topics: Biology
    Published by Springer
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