Omnivorous summer feeding by juvenile Antarctic krill in coastal waters
Abstract The Antarctic krill Euphausia superba is often considered an herbivore but is notable for its trophic flexibility, which includes feeding on protistan and metazoan zooplankton. Characterizing krill trophic position (TP) is important for understanding carbon and energy flow from phytoplankto...
Published in: | Limnology and Oceanography |
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Online Access: | http://dx.doi.org/10.1002/lno.12533 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12533 |
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crwiley:10.1002/lno.12533 2024-10-13T14:03:06+00:00 Omnivorous summer feeding by juvenile Antarctic krill in coastal waters Conroy, John A. Steinberg, Deborah K. Nardelli, Schuyler C. Schofield, Oscar National Oceanic and Atmospheric Administration National Science Foundation College of William and Mary Virginia Sea Grant, Virginia Institute of Marine Science 2024 http://dx.doi.org/10.1002/lno.12533 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12533 en eng Wiley http://creativecommons.org/licenses/by-nc/4.0/ Limnology and Oceanography volume 69, issue 4, page 874-887 ISSN 0024-3590 1939-5590 journal-article 2024 crwiley https://doi.org/10.1002/lno.12533 2024-09-17T04:49:19Z Abstract The Antarctic krill Euphausia superba is often considered an herbivore but is notable for its trophic flexibility, which includes feeding on protistan and metazoan zooplankton. Characterizing krill trophic position (TP) is important for understanding carbon and energy flow from phytoplankton to vertebrate predators and to the deep ocean, especially as plankton composition is sensitive to changing climate. We used repeated field sampling and experiments to study feeding by juvenile krill during three austral summers in waters near Palmer Station, Antarctica. Our approach was to combine seasonal carbon budgets, gut fluorescence measurements, imaging flow cytometry, and compound‐specific isotope analysis of amino acids. Field measurements coupled to experimentally derived grazing functional response curves suggest that phytoplankton grazing alone was insufficient to support the growth and basal metabolism of juvenile krill. Phytoplankton consumption by juvenile krill was limited due to inefficient feeding on nanoplankton (2–20 μ m), which constituted the majority of autotrophic prey. Mean krill TP and the metazoan dietary fraction increased in years with higher mesozooplankton biomass, which was not coupled to phytoplankton biomass. Comparing TP estimates using δ 15 N of different amino acids indicated a substantial and consistent food‐web contribution from heterotrophic protists. Phytoplankton, metazoans, and heterotrophic protists all were important contributors to a diverse krill diet that changed substantially among years. Juvenile krill fed mostly on heterotrophic prey during summer near Palmer Station, and this food web complexity should be considered more broadly throughout the changing Southern Ocean. Article in Journal/Newspaper Antarc* Antarctic Antarctic Krill Antarctica Euphausia superba Southern Ocean Wiley Online Library Antarctic Southern Ocean The Antarctic Austral Palmer Station ENVELOPE(-64.050,-64.050,-64.770,-64.770) Palmer-Station ENVELOPE(-64.050,-64.050,-64.770,-64.770) Limnology and Oceanography |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract The Antarctic krill Euphausia superba is often considered an herbivore but is notable for its trophic flexibility, which includes feeding on protistan and metazoan zooplankton. Characterizing krill trophic position (TP) is important for understanding carbon and energy flow from phytoplankton to vertebrate predators and to the deep ocean, especially as plankton composition is sensitive to changing climate. We used repeated field sampling and experiments to study feeding by juvenile krill during three austral summers in waters near Palmer Station, Antarctica. Our approach was to combine seasonal carbon budgets, gut fluorescence measurements, imaging flow cytometry, and compound‐specific isotope analysis of amino acids. Field measurements coupled to experimentally derived grazing functional response curves suggest that phytoplankton grazing alone was insufficient to support the growth and basal metabolism of juvenile krill. Phytoplankton consumption by juvenile krill was limited due to inefficient feeding on nanoplankton (2–20 μ m), which constituted the majority of autotrophic prey. Mean krill TP and the metazoan dietary fraction increased in years with higher mesozooplankton biomass, which was not coupled to phytoplankton biomass. Comparing TP estimates using δ 15 N of different amino acids indicated a substantial and consistent food‐web contribution from heterotrophic protists. Phytoplankton, metazoans, and heterotrophic protists all were important contributors to a diverse krill diet that changed substantially among years. Juvenile krill fed mostly on heterotrophic prey during summer near Palmer Station, and this food web complexity should be considered more broadly throughout the changing Southern Ocean. |
author2 |
National Oceanic and Atmospheric Administration National Science Foundation College of William and Mary Virginia Sea Grant, Virginia Institute of Marine Science |
format |
Article in Journal/Newspaper |
author |
Conroy, John A. Steinberg, Deborah K. Nardelli, Schuyler C. Schofield, Oscar |
spellingShingle |
Conroy, John A. Steinberg, Deborah K. Nardelli, Schuyler C. Schofield, Oscar Omnivorous summer feeding by juvenile Antarctic krill in coastal waters |
author_facet |
Conroy, John A. Steinberg, Deborah K. Nardelli, Schuyler C. Schofield, Oscar |
author_sort |
Conroy, John A. |
title |
Omnivorous summer feeding by juvenile Antarctic krill in coastal waters |
title_short |
Omnivorous summer feeding by juvenile Antarctic krill in coastal waters |
title_full |
Omnivorous summer feeding by juvenile Antarctic krill in coastal waters |
title_fullStr |
Omnivorous summer feeding by juvenile Antarctic krill in coastal waters |
title_full_unstemmed |
Omnivorous summer feeding by juvenile Antarctic krill in coastal waters |
title_sort |
omnivorous summer feeding by juvenile antarctic krill in coastal waters |
publisher |
Wiley |
publishDate |
2024 |
url |
http://dx.doi.org/10.1002/lno.12533 https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.1002/lno.12533 |
long_lat |
ENVELOPE(-64.050,-64.050,-64.770,-64.770) ENVELOPE(-64.050,-64.050,-64.770,-64.770) |
geographic |
Antarctic Southern Ocean The Antarctic Austral Palmer Station Palmer-Station |
geographic_facet |
Antarctic Southern Ocean The Antarctic Austral Palmer Station Palmer-Station |
genre |
Antarc* Antarctic Antarctic Krill Antarctica Euphausia superba Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctic Krill Antarctica Euphausia superba Southern Ocean |
op_source |
Limnology and Oceanography volume 69, issue 4, page 874-887 ISSN 0024-3590 1939-5590 |
op_rights |
http://creativecommons.org/licenses/by-nc/4.0/ |
op_doi |
https://doi.org/10.1002/lno.12533 |
container_title |
Limnology and Oceanography |
_version_ |
1812819527291895808 |