Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea
Abstract Phytoplankton growth and biomass accumulation vary spatially and temporally in the Ross Sea, largely as a function of ice concentrations, vertical mixing depths, and iron concentrations. To assess the role of vertical mixing in bloom initiation, we used a high-resolution numerical model to...
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Online Access: | http://dx.doi.org/10.1093/icesjms/fsu234 http://academic.oup.com/icesjms/article-pdf/72/6/1952/31226996/fsu234.pdf |
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croxfordunivpr:10.1093/icesjms/fsu234 2024-04-28T07:59:50+00:00 Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea Smith, Walker O. Jones, Randolph M. 2014 http://dx.doi.org/10.1093/icesjms/fsu234 http://academic.oup.com/icesjms/article-pdf/72/6/1952/31226996/fsu234.pdf en eng Oxford University Press (OUP) ICES Journal of Marine Science volume 72, issue 6, page 1952-1960 ISSN 1095-9289 1054-3139 Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography journal-article 2014 croxfordunivpr https://doi.org/10.1093/icesjms/fsu234 2024-04-09T07:57:52Z Abstract Phytoplankton growth and biomass accumulation vary spatially and temporally in the Ross Sea, largely as a function of ice concentrations, vertical mixing depths, and iron concentrations. To assess the role of vertical mixing in bloom initiation, we used a high-resolution numerical model to estimate changes in mixed layer depths from October 1 through early December, the period where phytoplankton growth begins and biomass accumulates, and estimate critical depths for this period. Mixed layers in October ranged from the complete water column (>600 m) to ca. 200 m; over a 60-day period, the mixed layers decreased on average by 70%. Estimated critical depths were exceeded in October, but would allow growth to proceed in late October due to shoaling of mixed layer depths, consistent with the known onset of the spring bloom in the Ross Sea. We also analysed a series of stations sampled near the Ross Ice Shelf during January 2012. Mean vertical profiles for the stations indicated deep vertical mixing; mixed layer depths averaged 60 m and ranged up to 96 m. Chlorophyll concentrations within the mixed layer averaged 6.60 µg l−1, and the pigment contributions were dominated by Phaeocystis antarctica. We suggest that this mesoscale region near the ice shelf is elevated in phytoplankton biomass due to frequent mixing events that redistribute biomass to depth and replenish nutrients, which in turn are utilized by an assemblage capable of utilizing low mean irradiance levels. Thus, the deep mixed layers and high biomass concentrations represent growth over long periods under reduced mixing punctuated by short periods of deeper vertical mixing that redistribute biomass. Water column vertical mixing and phytoplankton biomass in the Ross Sea are consistent with the critical depth concept as originally proposed by Sverdrup. Article in Journal/Newspaper Antarc* Antarctica Ice Shelf Ross Ice Shelf Ross Sea Oxford University Press ICES Journal of Marine Science 72 6 1952 1960 |
institution |
Open Polar |
collection |
Oxford University Press |
op_collection_id |
croxfordunivpr |
language |
English |
topic |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography |
spellingShingle |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography Smith, Walker O. Jones, Randolph M. Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea |
topic_facet |
Ecology Aquatic Science Ecology, Evolution, Behavior and Systematics Oceanography |
description |
Abstract Phytoplankton growth and biomass accumulation vary spatially and temporally in the Ross Sea, largely as a function of ice concentrations, vertical mixing depths, and iron concentrations. To assess the role of vertical mixing in bloom initiation, we used a high-resolution numerical model to estimate changes in mixed layer depths from October 1 through early December, the period where phytoplankton growth begins and biomass accumulates, and estimate critical depths for this period. Mixed layers in October ranged from the complete water column (>600 m) to ca. 200 m; over a 60-day period, the mixed layers decreased on average by 70%. Estimated critical depths were exceeded in October, but would allow growth to proceed in late October due to shoaling of mixed layer depths, consistent with the known onset of the spring bloom in the Ross Sea. We also analysed a series of stations sampled near the Ross Ice Shelf during January 2012. Mean vertical profiles for the stations indicated deep vertical mixing; mixed layer depths averaged 60 m and ranged up to 96 m. Chlorophyll concentrations within the mixed layer averaged 6.60 µg l−1, and the pigment contributions were dominated by Phaeocystis antarctica. We suggest that this mesoscale region near the ice shelf is elevated in phytoplankton biomass due to frequent mixing events that redistribute biomass to depth and replenish nutrients, which in turn are utilized by an assemblage capable of utilizing low mean irradiance levels. Thus, the deep mixed layers and high biomass concentrations represent growth over long periods under reduced mixing punctuated by short periods of deeper vertical mixing that redistribute biomass. Water column vertical mixing and phytoplankton biomass in the Ross Sea are consistent with the critical depth concept as originally proposed by Sverdrup. |
format |
Article in Journal/Newspaper |
author |
Smith, Walker O. Jones, Randolph M. |
author_facet |
Smith, Walker O. Jones, Randolph M. |
author_sort |
Smith, Walker O. |
title |
Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea |
title_short |
Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea |
title_full |
Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea |
title_fullStr |
Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea |
title_full_unstemmed |
Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea |
title_sort |
vertical mixing, critical depths, and phytoplankton growth in the ross sea |
publisher |
Oxford University Press (OUP) |
publishDate |
2014 |
url |
http://dx.doi.org/10.1093/icesjms/fsu234 http://academic.oup.com/icesjms/article-pdf/72/6/1952/31226996/fsu234.pdf |
genre |
Antarc* Antarctica Ice Shelf Ross Ice Shelf Ross Sea |
genre_facet |
Antarc* Antarctica Ice Shelf Ross Ice Shelf Ross Sea |
op_source |
ICES Journal of Marine Science volume 72, issue 6, page 1952-1960 ISSN 1095-9289 1054-3139 |
op_doi |
https://doi.org/10.1093/icesjms/fsu234 |
container_title |
ICES Journal of Marine Science |
container_volume |
72 |
container_issue |
6 |
container_start_page |
1952 |
op_container_end_page |
1960 |
_version_ |
1797572343260774400 |