Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current
Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited Antarctic Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep ocean and sediments. Because the Southern Ocean is...
Published in: | Proceedings of the National Academy of Sciences |
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National Academy of Sciences
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Online Access: | https://oceanrep.geomar.de/id/eprint/22952/ https://oceanrep.geomar.de/id/eprint/22952/1/PNAS-2013-Assmy-20633-8.pdf https://doi.org/10.1073/pnas.1309345110 |
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ftoceanrep:oai:oceanrep.geomar.de:22952 2023-05-15T14:04:17+02:00 Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current Assmy, P. Smetacek, V. Montresor, M. Klaas, C. Henjes, J. Strass, V. H. Arrieta, J. M. Bathmann, U. Berg, G. M. Breitbarth, Eike Cisewski, B. Friedrichs, L. Fuchs, N. Herndl, G. J. Jansen, S. Kragefsky, S. Latasa, M. Peeken, Ilka Rottgers, R. Scharek, R. Schuller, S. E. Steigenberger, S. Webb, A. Wolf-Gladrow, D. 2013 text https://oceanrep.geomar.de/id/eprint/22952/ https://oceanrep.geomar.de/id/eprint/22952/1/PNAS-2013-Assmy-20633-8.pdf https://doi.org/10.1073/pnas.1309345110 en eng National Academy of Sciences https://oceanrep.geomar.de/id/eprint/22952/1/PNAS-2013-Assmy-20633-8.pdf Assmy, P., Smetacek, V., Montresor, M., Klaas, C., Henjes, J., Strass, V. H., Arrieta, J. M., Bathmann, U., Berg, G. M., Breitbarth, E., Cisewski, B., Friedrichs, L., Fuchs, N., Herndl, G. J., Jansen, S., Kragefsky, S., Latasa, M., Peeken, I., Rottgers, R., Scharek, R., Schuller, S. E., Steigenberger, S., Webb, A. and Wolf-Gladrow, D. (2013) Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current. PNAS Proceedings of the National Academy of Sciences of the United States of America, 110 (51). pp. 20633-20638. DOI 10.1073/pnas.1309345110 <https://doi.org/10.1073/pnas.1309345110>. doi:10.1073/pnas.1309345110 info:eu-repo/semantics/embargoedAccess Article PeerReviewed 2013 ftoceanrep https://doi.org/10.1073/pnas.1309345110 2023-04-07T15:11:38Z Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited Antarctic Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep ocean and sediments. Because the Southern Ocean is the major hub of oceanic nutrient distribution, selective silicon sequestration there limits diatom blooms elsewhere and consequently the biotic carbon sequestration potential of the entire ocean. We investigated this paradox in an in situ iron fertilization experiment by comparing accumulation and sinking of diatom populations inside and outside the iron-fertilized patch over 5 wk. A bloom comprising various thin- and thick-shelled diatom species developed inside the patch despite the presence of large grazer populations. After the third week, most of the thinner-shelled diatom species underwent mass mortality, formed large, mucous aggregates, and sank out en masse (carbon sinkers). In contrast, thicker-shelled species, in particular Fragilariopsis kerguelensis, persisted in the surface layers, sank mainly empty shells continuously, and reduced silicate concentrations to similar levels both inside and outside the patch (silica sinkers). These patterns imply that thick-shelled, hence grazer-protected, diatom species evolved in response to heavy copepod grazing pressure in the presence of an abundant silicate supply. The ecology of these silica-sinking species decouples silicon and carbon cycles in the iron-limited Southern Ocean, whereas carbon-sinking species, when stimulated by iron fertilization, export more carbon per silicon. Our results suggest that large-scale iron fertilization of the silicate-rich Southern Ocean will not change silicon sequestration but will add carbon to the sinking silica flux. Article in Journal/Newspaper Antarc* Antarctic North Atlantic Southern Ocean OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Antarctic Southern Ocean Proceedings of the National Academy of Sciences 110 51 20633 20638 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited Antarctic Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep ocean and sediments. Because the Southern Ocean is the major hub of oceanic nutrient distribution, selective silicon sequestration there limits diatom blooms elsewhere and consequently the biotic carbon sequestration potential of the entire ocean. We investigated this paradox in an in situ iron fertilization experiment by comparing accumulation and sinking of diatom populations inside and outside the iron-fertilized patch over 5 wk. A bloom comprising various thin- and thick-shelled diatom species developed inside the patch despite the presence of large grazer populations. After the third week, most of the thinner-shelled diatom species underwent mass mortality, formed large, mucous aggregates, and sank out en masse (carbon sinkers). In contrast, thicker-shelled species, in particular Fragilariopsis kerguelensis, persisted in the surface layers, sank mainly empty shells continuously, and reduced silicate concentrations to similar levels both inside and outside the patch (silica sinkers). These patterns imply that thick-shelled, hence grazer-protected, diatom species evolved in response to heavy copepod grazing pressure in the presence of an abundant silicate supply. The ecology of these silica-sinking species decouples silicon and carbon cycles in the iron-limited Southern Ocean, whereas carbon-sinking species, when stimulated by iron fertilization, export more carbon per silicon. Our results suggest that large-scale iron fertilization of the silicate-rich Southern Ocean will not change silicon sequestration but will add carbon to the sinking silica flux. |
format |
Article in Journal/Newspaper |
author |
Assmy, P. Smetacek, V. Montresor, M. Klaas, C. Henjes, J. Strass, V. H. Arrieta, J. M. Bathmann, U. Berg, G. M. Breitbarth, Eike Cisewski, B. Friedrichs, L. Fuchs, N. Herndl, G. J. Jansen, S. Kragefsky, S. Latasa, M. Peeken, Ilka Rottgers, R. Scharek, R. Schuller, S. E. Steigenberger, S. Webb, A. Wolf-Gladrow, D. |
spellingShingle |
Assmy, P. Smetacek, V. Montresor, M. Klaas, C. Henjes, J. Strass, V. H. Arrieta, J. M. Bathmann, U. Berg, G. M. Breitbarth, Eike Cisewski, B. Friedrichs, L. Fuchs, N. Herndl, G. J. Jansen, S. Kragefsky, S. Latasa, M. Peeken, Ilka Rottgers, R. Scharek, R. Schuller, S. E. Steigenberger, S. Webb, A. Wolf-Gladrow, D. Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current |
author_facet |
Assmy, P. Smetacek, V. Montresor, M. Klaas, C. Henjes, J. Strass, V. H. Arrieta, J. M. Bathmann, U. Berg, G. M. Breitbarth, Eike Cisewski, B. Friedrichs, L. Fuchs, N. Herndl, G. J. Jansen, S. Kragefsky, S. Latasa, M. Peeken, Ilka Rottgers, R. Scharek, R. Schuller, S. E. Steigenberger, S. Webb, A. Wolf-Gladrow, D. |
author_sort |
Assmy, P. |
title |
Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current |
title_short |
Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current |
title_full |
Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current |
title_fullStr |
Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current |
title_full_unstemmed |
Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current |
title_sort |
thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited antarctic circumpolar current |
publisher |
National Academy of Sciences |
publishDate |
2013 |
url |
https://oceanrep.geomar.de/id/eprint/22952/ https://oceanrep.geomar.de/id/eprint/22952/1/PNAS-2013-Assmy-20633-8.pdf https://doi.org/10.1073/pnas.1309345110 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic North Atlantic Southern Ocean |
genre_facet |
Antarc* Antarctic North Atlantic Southern Ocean |
op_relation |
https://oceanrep.geomar.de/id/eprint/22952/1/PNAS-2013-Assmy-20633-8.pdf Assmy, P., Smetacek, V., Montresor, M., Klaas, C., Henjes, J., Strass, V. H., Arrieta, J. M., Bathmann, U., Berg, G. M., Breitbarth, E., Cisewski, B., Friedrichs, L., Fuchs, N., Herndl, G. J., Jansen, S., Kragefsky, S., Latasa, M., Peeken, I., Rottgers, R., Scharek, R., Schuller, S. E., Steigenberger, S., Webb, A. and Wolf-Gladrow, D. (2013) Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current. PNAS Proceedings of the National Academy of Sciences of the United States of America, 110 (51). pp. 20633-20638. DOI 10.1073/pnas.1309345110 <https://doi.org/10.1073/pnas.1309345110>. doi:10.1073/pnas.1309345110 |
op_rights |
info:eu-repo/semantics/embargoedAccess |
op_doi |
https://doi.org/10.1073/pnas.1309345110 |
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Proceedings of the National Academy of Sciences |
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110 |
container_issue |
51 |
container_start_page |
20633 |
op_container_end_page |
20638 |
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1766275318010609664 |