The association of Antarctic krill Euphausia superba with the under-ice habitat

The association of Antarctic krill Euphausia superba with the under-ice habitat

The association of Antarctic krill Euphausia superba with the under-ice habitat was investigated in the Lazarev Sea (Southern Ocean) during austral summer, autumn and winter. Data were obtained using novel Surface and Under Ice Trawls (SUIT), which sampled the 0-2 m surface layer both under sea ice...

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Bibliographic Details
Published in:PloS one Vol. 7; no. 2; p. e31775
Main Authors: Flores, Hauke, van Franeker, Jan Andries, Siegel, Volker, Haraldsson, Matilda, Strass, Volker, Meesters, Erik Hubert, Bathmann, Ulrich, Wolff, Willem Jan
Format: Journal Article
Language:English
Published: United States Public Library of Science 23-02-2012
Public Library of Science (PLoS)
Subjects:
Algae
Animals
Antarctic climate
Antarctic climate changes
Antarctic Regions
Autumn
Biology
Biomass
Biota
Climate
Climate Change
community structure
Daption capense
Ecology
Ecosystem
Ecosystem biology
Ecosystems
Ekologi
elephant island
energy budgets
Environment
Environmental changes
Euphausia superba
Euphausiacea
Euphausiacea - physiology
Fisheries management
Food chains
Foraging behavior
Fulmarus glacialoides
Global temperature changes
Habitats
Ice
Ice Cover
Ice-water interface
Krill
lazarev sea
Marine ecology
Mathematical models
Mixed layer depth
Mud-water interfaces
Normal Distribution
northern weddell sea
Oceans and Seas
pack-ice
Pagodroma nivea
Polar environments
Population (statistical)
Population Density
Population Dynamics
Population number
Science
Sea ice
Seasons
southern-ocean
Statistical analysis
Statistical models
Studies
Summer
Surface boundary layer
Surface layers
Temperature
Thalassoica antarctica
Trawling
Trawls
trophic relationships
Winter
Antarctic Regions
Lazarev Sea
Netherlands
Antarctica
Texel (island)
Germany
Southern Ocean
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Summary:The association of Antarctic krill Euphausia superba with the under-ice habitat was investigated in the Lazarev Sea (Southern Ocean) during austral summer, autumn and winter. Data were obtained using novel Surface and Under Ice Trawls (SUIT), which sampled the 0-2 m surface layer both under sea ice and in open water. Average surface layer densities ranged between 0.8 individuals m(-2) in summer and autumn, and 2.7 individuals m(-2) in winter. In summer, under-ice densities of Antarctic krill were significantly higher than in open waters. In autumn, the opposite pattern was observed. Under winter sea ice, densities were often low, but repeatedly far exceeded summer and autumn maxima. Statistical models showed that during summer high densities of Antarctic krill in the 0-2 m layer were associated with high ice coverage and shallow mixed layer depths, among other factors. In autumn and winter, density was related to hydrographical parameters. Average under-ice densities from the 0-2 m layer were higher than corresponding values from the 0-200 m layer collected with Rectangular Midwater Trawls (RMT) in summer. In winter, under-ice densities far surpassed maximum 0-200 m densities on several occasions. This indicates that the importance of the ice-water interface layer may be under-estimated by the pelagic nets and sonars commonly used to estimate the population size of Antarctic krill for management purposes, due to their limited ability to sample this habitat. Our results provide evidence for an almost year-round association of Antarctic krill with the under-ice habitat, hundreds of kilometres into the ice-covered area of the Lazarev Sea. Local concentrations of postlarval Antarctic krill under winter sea ice suggest that sea ice biota are important for their winter survival. These findings emphasise the susceptibility of an ecological key species to changing sea ice habitats, suggesting potential ramifications on Antarctic ecosystems induced by climate change.
Bibliography:Conceived and designed the experiments: JAF HF WJW. Performed the experiments: HF JAF VS MH VS. Analyzed the data: HF HWGM. Contributed reagents/materials/analysis tools: HF JAF VS UB. Wrote the paper: HF JAF VS MH VS HWGM UB WJW.
Current address: Alfred Wegener Institute for Polar and Marine Research (AWI), Bremerhaven, Germany
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0031775