Publication Date:
2019-07-16
Description:
The macrozooplankton and micronekton community of the Lazarev Sea (Southern Ocean) was
investigated at 3 depth layers during austral summer, autumn and winter: (1) the surface layer
(0–2 m); (2) the epipelagic layer (0–200 m); and (3) the deep layer (0–3000 m). Altogether, 132 species
were identified. Species composition changed with depth from a euphausiid-dominated community in
the surface layer, via a siphonophore-dominated community in the epipelagic layer, to a chaetognath-dominated
community in the deep layer. The surface layer community predominantly changed along
gradients of surface water temperature and sea ice parameters, whereas the epipelagic community
mainly changed along hydrographical gradients. Although representing only 1% of the depth range of the
epipelagic layer, mean per-area macrofauna densities in the surface layer ranged at 8% of corresponding
epipelagic densities in summer, 6% in autumn, and 24% in winter. Seasonal shifts of these proportional
densities in abundant species indicated different strategies in the use of the surface layer, including both
hibernal downward and hibernal upward shift in the vertical distribution, as well as year-round surface
layer use by Antarctic krill. These findings imply that the surface layer, especially when it is ice-covered,
is an important functional node of the pelagic ecosystem that has been underestimated by conventional
depth-integrated sampling in the past. The exposure of this key habitat to climate-driven forces most
likely adds to the known susceptibility of Antarctic pelagic ecosystems to temperature rise and changing
sea ice conditions.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
Format:
application/pdf
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