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The structure of upper level pelagic food webs in the antarctic. Effect of phytoplankton distribution
Ainley, D.G.; Fraser, W.R.; Smith Jr., W.O.; Hopkins, T.L.; Torres, J.J. (1991). The structure of upper level pelagic food webs in the antarctic. Effect of phytoplankton distribution, in: Nihoul, J.C.J. et al. Ice covered seas and ice edges. Physical, chemical and biological processes and interactions: proceedings of the 22th International Liège Colloquium on Ocean Hydrodynamics. Journal of Marine Systems, 2: pp. 111-122
In: Nihoul, J.C.J.; Djenidi, S. (1991). Ice covered seas and ice edges. Physical, chemical and biological processes and interactions: proceedings of the 22th International Liège Colloquium on Ocean Hydrodynamics. Journal of Marine Systems, 2. Elsevier Science Publishers: Amsterdam. 520 pp., more
In: Journal of Marine Systems. Elsevier: Tokyo; Oxford; New York; Amsterdam. ISSN 0924-7963, more
Peer reviewed article  

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Keyword
    Marine

Authors  Top 
  • Ainley, D.G.
  • Fraser, W.R.
  • Smith Jr., W.O.
  • Hopkins, T.L.
  • Torres, J.J.

Abstract
    We investigated diet composition and diversity and the diet overlap between species within the seabird community of the Scotia-Weddell Confluence region, Antarctica, during spring, autumn and winter. Seasonal changes in diet characteristics and overlap among species were viewed in the context of changes in prey availability as a function of vertical distribution in the water column. The latter was in turn affected by where phytoplankton and associated grazers were located. When primary productivity was confined to the pack ice during winter, thus bringing grazers and their predators closer to the surface, micronekton were much more vulnerable to avian predators and the latter were able to select prey on the basis of energetic value. As a consequence the upper food web was much less diffuse than during the other seasons when prey occurred throughout the upper portion of the water column and predators had to be opportunistic. The mobility of micronekton and nekton bring some structure to the upper portion of marine food webs, thereby introducing seasonal variability of trophic relationships within Antarctic food webs.

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