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Seabed foraging by Antarctic krill: implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron

Seabed foraging by Antarctic krill: implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron
Seabed foraging by Antarctic krill: implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron
A compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent
benthic habitats year-round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and
acoustic data from the Scotia Sea show that in summer 2–20% of the population reside at depths between 200 and
2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of
krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage,
might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach
content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is
the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in
upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and
seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this
iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding,
and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface
waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes
involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental
repositories.
0024-3590
1411-1428
Schmidt, Katrin
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Atkinson, Angus
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Steigenberger, Sebastian
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Fielding, Sophie
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Lindsay, Margaret C. M.
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Pond, David W.
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Tarling, Geraint A.
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Klevjer, Thor A.
aed7c5ec-6145-4875-9f39-310320cfe206
Allen, Claire S.
7c197775-c25e-4555-84e3-b4621354aac0
Nicol, Stephen
66d82bbc-7118-418c-a29a-5ec9e5403cd9
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Schmidt, Katrin
1eccc7f0-b656-4c41-a9bd-543ef7aefb5c
Atkinson, Angus
77d9c544-2749-46fe-b991-df2a11d1d6be
Steigenberger, Sebastian
15c989b8-dd0d-454c-b3cc-08d4290eaff0
Fielding, Sophie
b6810aca-528b-41d9-b23e-3e05647c5fab
Lindsay, Margaret C. M.
7f49d7b9-c483-42eb-a7c7-26283da952ee
Pond, David W.
0c83d1f3-f262-4ab5-9116-ba19e1056406
Tarling, Geraint A.
d7d95281-b939-4f83-8e5c-224949844dcc
Klevjer, Thor A.
aed7c5ec-6145-4875-9f39-310320cfe206
Allen, Claire S.
7c197775-c25e-4555-84e3-b4621354aac0
Nicol, Stephen
66d82bbc-7118-418c-a29a-5ec9e5403cd9
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9

Schmidt, Katrin, Atkinson, Angus, Steigenberger, Sebastian, Fielding, Sophie, Lindsay, Margaret C. M., Pond, David W., Tarling, Geraint A., Klevjer, Thor A., Allen, Claire S., Nicol, Stephen and Achterberg, Eric P. (2011) Seabed foraging by Antarctic krill: implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron. Limnology and Oceanography, 56 (4), 1411-1428. (doi:10.4319/lo.2011.56.4.1411).

Record type: Article

Abstract

A compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent
benthic habitats year-round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and
acoustic data from the Scotia Sea show that in summer 2–20% of the population reside at depths between 200 and
2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of
krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage,
might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach
content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is
the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in
upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and
seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this
iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding,
and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface
waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes
involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental
repositories.

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Published date: 2011
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 192337
URI: http://eprints.soton.ac.uk/id/eprint/192337
ISSN: 0024-3590
PURE UUID: e16897b6-cf2c-461a-b727-68a16b9e6ada

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Date deposited: 01 Jul 2011 15:57
Last modified: 20 Nov 2021 03:23

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Contributors

Author: Katrin Schmidt
Author: Angus Atkinson
Author: Sebastian Steigenberger
Author: Sophie Fielding
Author: Margaret C. M. Lindsay
Author: David W. Pond
Author: Geraint A. Tarling
Author: Thor A. Klevjer
Author: Claire S. Allen
Author: Stephen Nicol

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