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Feeding ecology of pelagic nekton

Element 1

Trophic ecology of the benthopelagic community of the Sedlo seamount in the southern MAR-ECO sub-area. (Part of the EU funded OASIS project). Principal Investigator: Bernd Christiansen (Germany)

Element 2

Trophic ecology and food-webs of fish and cephalopods of the Mid-Atlantic Ridge. Principal Investigator: Aage Hoines (Norway).

Aims

1. Classify nekton species according to feeding pattern.
2. Identify intraspecific variation, e.g. changes in diet and feeding pattern with
size.
3. Identify major interspecific linkages (predator-prey relationships).
4. Derive conceptual food-web models that can be linked to similar models for
zooplankton and epibenthos.
5. Compare interspecific patterns and trophic transfer processes between subareas
of the MAR-ECO area.
6. Compare patterns observed on the MAR with those in continental slope waters
based on previously collected data.

Hypothesis

  • The main prey resources of the deep scattering layer fish and cephalopods are vertically migrating crustacean plankton and micronekton.
  • The main prey of the benthopelagic and benthic fish and cephalopods are pelagic and benthopelagic plankton and nekton.
  • For non-piscivorous nekton, crustaceans are the more significant prey taxon, and only few species are adapted to feeding on e.g. gelatinous prey organisms.
  • The main processes providing these patterns are the vertical migration of prey species, and the concentration of food organisms on slopes and near seamounts.
  • Observed feeding patterns are the same in all sub-areas, and similar to those observed on adjacent continental slopes.
  • NOTE: Element 1 have more specific hypotheses concerning seamount processes (See OASIS website).

Strategy

Element 1: Focused studies on the Sedlo seamount and adjacent waters. Material from OASIS cruises only.
Element 2: Focused studies in the three MAR-ECO sub-areas, but also opportunistic sampling in other areas.

Technology/Methods

o Traditional stomach content analyses (but using modern sampling methods).
o Biochemical analyses (fatty acid biomarkers, 15N, 13C, 234Th, ETS activity, DNA analyses)
o Comparative analyses of feeding modes based on morphological/anatomical features and behaviour.
o Multivariate analyses, diet overlap indices.
o ECOPATH model

Schedule

Preparation of field work: 2002-2003, Sampling at sea: 2003-2005, Analysis and dissemination: 2005-2008.

Partners

Element 1: OASIS partners, e.g. Bernd Christiansen, Gui Menezes, Telmo Morato Gomes (Portugal) a.o.
Element 2: Tracey Sutton (USA), O.A. Bergstad, ge Hines, Tonje Castberg, Agnes Gundersen, Ruth Anne Sandaa (Norway), Franz Uiblein (Austria), Andrey Dolgov (Russia).

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