Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica
Abstract Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial hetero...
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ftdoajarticles:oai:doaj.org/article:e3bd0c86ccde44e288e6b85570d2b308 2023-05-15T13:23:59+02:00 Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica C.M. Williams A.M. Dupont J. Loevenich A.F. Post J. Dinasquet P.L. Yager 2016-04-01T00:00:00Z https://doi.org/10.12952/journal.elementa.000102 https://doaj.org/article/e3bd0c86ccde44e288e6b85570d2b308 EN eng BioOne http://elementascience.org/article/info:doi/10.12952/journal.elementa.000102 https://doaj.org/toc/2325-1026 2325-1026 doi:10.12952/journal.elementa.000102 https://doaj.org/article/e3bd0c86ccde44e288e6b85570d2b308 Elementa: Science of the Anthropocene (2016) Antarctic polynyas marine microbial activity carbon cycling Environmental sciences GE1-350 article 2016 ftdoajarticles https://doi.org/10.12952/journal.elementa.000102 2022-12-31T13:29:10Z Abstract Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP). Bacterial abundance, production (BP), respiration, growth efficiency, and extracellular enzyme activity (EEA) were compared to nutrient and organic matter inventories, chlorophyll a (Chl a), viral and microzooplankton abundance, and net primary production (NPP). Bacterial production and respiration clearly responded (0.04–4.0 and 10–53 µg C L−1 d−1, respectively) to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2–22 µg L−1), with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC) were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP:NPP ratio (2.1–9.4%) was relatively low. Bacterial respiration was also high, and growth efficiency (2–27%; median = 10%) was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8–2.8 g C m−2 d−1) was a high fraction (25–128%; median = 43%) of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 µm) accounted for a majority (∼ 75%) of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20°C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season. Article in Journal/Newspaper Amundsen Sea Antarc* Antarctic Antarctica Ross Sea Directory of Open Access Journals: DOAJ Articles Amundsen Sea Antarctic Ross Sea Elementa: Science of the Anthropocene 4 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Antarctic polynyas marine microbial activity carbon cycling Environmental sciences GE1-350 |
spellingShingle |
Antarctic polynyas marine microbial activity carbon cycling Environmental sciences GE1-350 C.M. Williams A.M. Dupont J. Loevenich A.F. Post J. Dinasquet P.L. Yager Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica |
topic_facet |
Antarctic polynyas marine microbial activity carbon cycling Environmental sciences GE1-350 |
description |
Abstract Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP). Bacterial abundance, production (BP), respiration, growth efficiency, and extracellular enzyme activity (EEA) were compared to nutrient and organic matter inventories, chlorophyll a (Chl a), viral and microzooplankton abundance, and net primary production (NPP). Bacterial production and respiration clearly responded (0.04–4.0 and 10–53 µg C L−1 d−1, respectively) to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2–22 µg L−1), with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC) were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP:NPP ratio (2.1–9.4%) was relatively low. Bacterial respiration was also high, and growth efficiency (2–27%; median = 10%) was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8–2.8 g C m−2 d−1) was a high fraction (25–128%; median = 43%) of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 µm) accounted for a majority (∼ 75%) of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20°C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season. |
format |
Article in Journal/Newspaper |
author |
C.M. Williams A.M. Dupont J. Loevenich A.F. Post J. Dinasquet P.L. Yager |
author_facet |
C.M. Williams A.M. Dupont J. Loevenich A.F. Post J. Dinasquet P.L. Yager |
author_sort |
C.M. Williams |
title |
Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica |
title_short |
Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica |
title_full |
Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica |
title_fullStr |
Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica |
title_full_unstemmed |
Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica |
title_sort |
pelagic microbial heterotrophy in response to a highly productive bloom of phaeocystis antarctica in the amundsen sea polynya, antarctica |
publisher |
BioOne |
publishDate |
2016 |
url |
https://doi.org/10.12952/journal.elementa.000102 https://doaj.org/article/e3bd0c86ccde44e288e6b85570d2b308 |
geographic |
Amundsen Sea Antarctic Ross Sea |
geographic_facet |
Amundsen Sea Antarctic Ross Sea |
genre |
Amundsen Sea Antarc* Antarctic Antarctica Ross Sea |
genre_facet |
Amundsen Sea Antarc* Antarctic Antarctica Ross Sea |
op_source |
Elementa: Science of the Anthropocene (2016) |
op_relation |
http://elementascience.org/article/info:doi/10.12952/journal.elementa.000102 https://doaj.org/toc/2325-1026 2325-1026 doi:10.12952/journal.elementa.000102 https://doaj.org/article/e3bd0c86ccde44e288e6b85570d2b308 |
op_doi |
https://doi.org/10.12952/journal.elementa.000102 |
container_title |
Elementa: Science of the Anthropocene |
container_volume |
4 |
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1766376725464219648 |