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  • Biodiversity Journal  (1)
  • SPRINGER  (1)
  • 2015-2019  (2)
  • 2017  (2)
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  • 2015-2019  (2)
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  • 1
    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
    Format: application/pdf
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  • 2
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    Biodiversity Journal
    In:  EPIC317th International Colloquium on Amphipoda, Trapani, Sicily, Italy, 2017-09Biodiversity Journal
    Publication Date: 2022-09-29
    Description: Hyperiid amphipod crustaceans are abundant in Southern Ocean waters from the Polar Frontal Zone to shelf waters where they represent a major prey for fish and seabirds. Hyperiella dilatata has evolved a peculiar anti-predatory behaviour: it abducts chemically-protected, shell-less pteropods from the water column and carries them on their dorsal side, holding it between its pereopods (McClintock & Janssen, 1990). The pteropod Clione antarctica produces de novo a predator-deterrent chemical named pteroenone (Bryan et al., 1995). Tandem pairs of pteropods and amphipods were significantly less predated upon than single individuals of Hyperiella and hence this behaviour is very efficient as protection from visually hunting icefish in the crystal-clear shelf waters around the continent (McClintock & Janssen, 1990), however, in the open ocean this behaviour was so far undocumented. We report this association at four different open-water sites in the Southern Ocean between 45 and 71°S and develop hypotheses on its origin and function. H. dilatata abducted Spongiobranchaea pteropods in the Polar Frontal Zone and Clione further south in the Weddell Sea. Lengths of the abducted pteropods varied greatly; the biggest pteropod carried was around half the host’s size. Molecular barcodes of both host and pteropods were obtained. Finally, we hypothesize against which potential predators this anti-predatory behaviour may have been selected for.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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