Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand
International audience The Subantarctic zone is one of the largest High-Nutrient Low-Chlorophyll zones of the Southern Ocean. Despite widespread iron limitation, phytoplankton accumulation (chlorophyll a (chla) > 0.3 mg m -3 ) often occurs near islands and bathymetric features such as on the Camp...
Published in: | Journal of Geophysical Research: Oceans |
---|---|
Main Authors: | , , , , , , , , |
Other Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2020
|
Subjects: | |
Online Access: | https://hal.science/hal-03859049 https://doi.org/10.1029/2019JC015550 |
id |
ftsorbonneuniv:oai:HAL:hal-03859049v1 |
---|---|
record_format |
openpolar |
spelling |
ftsorbonneuniv:oai:HAL:hal-03859049v1 2024-05-12T08:11:30+00:00 Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand Gutiérrez-Rodríguez, A. Safi, K. Fernández, D. Forcén-Vázquez, A. Gourvil, P. Hoffmann, L. Pinkerton, M. Sutton, P. Nodder, S. D. Station biologique de Roscoff = Roscoff Marine Station (SBR) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Fédération de recherche de Roscoff (FR2424) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) 2020 https://hal.science/hal-03859049 https://doi.org/10.1029/2019JC015550 en eng HAL CCSD Wiley-Blackwell info:eu-repo/semantics/altIdentifier/doi/10.1029/2019JC015550 hal-03859049 https://hal.science/hal-03859049 BIBCODE: 2020JGRC.12515550G doi:10.1029/2019JC015550 ISSN: 2169-9275 EISSN: 2169-9291 Journal of Geophysical Research. Oceans https://hal.science/hal-03859049 Journal of Geophysical Research. Oceans, 2020, 125, ⟨10.1029/2019JC015550⟩ phytoplankton primary production growth rate mixed-layer depth southern ocean microzooplankton grazing [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2020 ftsorbonneuniv https://doi.org/10.1029/2019JC015550 2024-04-18T03:29:42Z International audience The Subantarctic zone is one of the largest High-Nutrient Low-Chlorophyll zones of the Southern Ocean. Despite widespread iron limitation, phytoplankton accumulation (chlorophyll a (chla) > 0.3 mg m -3 ) often occurs near islands and bathymetric features such as on the Campbell Plateau, southeast of New Zealand. To investigate the processes responsible for localized increases in chla commonly observed by satellites, we characterized phytoplankton biomass structure, production, and microzooplankton grazing on Campbell Plateau and surrounding waters in austral autumn (March 2017). Chla on the plateau tended to be higher, more variable (0.52 ± 0.38 mg chla m -3 , mean ± standard deviation), and characterized by larger phytoplankton forms (22 ± 27%chla > 20 μm) than surrounding waters (0.29 ± 0.12 mg chla m -3 , 5 ± 2%). The increased contribution of diatoms, together with higher photosystem II maximum photochemical efficiency (Fv/Fm = 0.45 ± 0.05) and lower effective absorption cross-section (σ PSII = 774 ± 90 Å RCII -1 ) on the plateau, suggests an alleviation of iron stress relative to surrounding waters (Fv/Fm = 0.37 ± 0.04, σ PSII = 974 ± 89 Å RCII -1 ). Phytoplankton growth (μ 0 = 0.42 ± 0.20 day -1 ) and production rates (6.1 ± 3.2 mg C m -3 day -1 ) were also higher compared to surrounding waters (0.27 ± 0.04 day -1 , 3.5 ± 1.9 mg C m -3 day -1 ). While microzooplankton grazing (g = 0.28 ± 0.18 day -1 ) balanced phytoplankton growth off the plateau (g:μ 0 = 1.13 ± 0.18), the imbalance observed on Campbell Plateau (g = 0.25 ± 0.25 day -1 ) allowed a substantial proportion of primary production to escape microzooplankton grazing control (g:μ 0 = 0.48 ± 0.31). Overall, the degree of coupling tended to decrease with the depth of the mixed layer (R 2 > 0.6, p < 0.001). We hypothesize that the entrainment of deeper water into the mixed layer regulates the onset and fate of the autumn bloom by altering nutrient supply and microzooplankton grazing pressure. Article in Journal/Newspaper Southern Ocean HAL Sorbonne Université Southern Ocean Austral New Zealand Campbell Plateau ENVELOPE(171.000,171.000,-50.667,-50.667) Near Islands ENVELOPE(173.132,173.132,52.801,52.801) Journal of Geophysical Research: Oceans 125 2 |
institution |
Open Polar |
collection |
HAL Sorbonne Université |
op_collection_id |
ftsorbonneuniv |
language |
English |
topic |
phytoplankton primary production growth rate mixed-layer depth southern ocean microzooplankton grazing [SDU]Sciences of the Universe [physics] |
spellingShingle |
phytoplankton primary production growth rate mixed-layer depth southern ocean microzooplankton grazing [SDU]Sciences of the Universe [physics] Gutiérrez-Rodríguez, A. Safi, K. Fernández, D. Forcén-Vázquez, A. Gourvil, P. Hoffmann, L. Pinkerton, M. Sutton, P. Nodder, S. D. Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand |
topic_facet |
phytoplankton primary production growth rate mixed-layer depth southern ocean microzooplankton grazing [SDU]Sciences of the Universe [physics] |
description |
International audience The Subantarctic zone is one of the largest High-Nutrient Low-Chlorophyll zones of the Southern Ocean. Despite widespread iron limitation, phytoplankton accumulation (chlorophyll a (chla) > 0.3 mg m -3 ) often occurs near islands and bathymetric features such as on the Campbell Plateau, southeast of New Zealand. To investigate the processes responsible for localized increases in chla commonly observed by satellites, we characterized phytoplankton biomass structure, production, and microzooplankton grazing on Campbell Plateau and surrounding waters in austral autumn (March 2017). Chla on the plateau tended to be higher, more variable (0.52 ± 0.38 mg chla m -3 , mean ± standard deviation), and characterized by larger phytoplankton forms (22 ± 27%chla > 20 μm) than surrounding waters (0.29 ± 0.12 mg chla m -3 , 5 ± 2%). The increased contribution of diatoms, together with higher photosystem II maximum photochemical efficiency (Fv/Fm = 0.45 ± 0.05) and lower effective absorption cross-section (σ PSII = 774 ± 90 Å RCII -1 ) on the plateau, suggests an alleviation of iron stress relative to surrounding waters (Fv/Fm = 0.37 ± 0.04, σ PSII = 974 ± 89 Å RCII -1 ). Phytoplankton growth (μ 0 = 0.42 ± 0.20 day -1 ) and production rates (6.1 ± 3.2 mg C m -3 day -1 ) were also higher compared to surrounding waters (0.27 ± 0.04 day -1 , 3.5 ± 1.9 mg C m -3 day -1 ). While microzooplankton grazing (g = 0.28 ± 0.18 day -1 ) balanced phytoplankton growth off the plateau (g:μ 0 = 1.13 ± 0.18), the imbalance observed on Campbell Plateau (g = 0.25 ± 0.25 day -1 ) allowed a substantial proportion of primary production to escape microzooplankton grazing control (g:μ 0 = 0.48 ± 0.31). Overall, the degree of coupling tended to decrease with the depth of the mixed layer (R 2 > 0.6, p < 0.001). We hypothesize that the entrainment of deeper water into the mixed layer regulates the onset and fate of the autumn bloom by altering nutrient supply and microzooplankton grazing pressure. |
author2 |
Station biologique de Roscoff = Roscoff Marine Station (SBR) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) Fédération de recherche de Roscoff (FR2424) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Gutiérrez-Rodríguez, A. Safi, K. Fernández, D. Forcén-Vázquez, A. Gourvil, P. Hoffmann, L. Pinkerton, M. Sutton, P. Nodder, S. D. |
author_facet |
Gutiérrez-Rodríguez, A. Safi, K. Fernández, D. Forcén-Vázquez, A. Gourvil, P. Hoffmann, L. Pinkerton, M. Sutton, P. Nodder, S. D. |
author_sort |
Gutiérrez-Rodríguez, A. |
title |
Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand |
title_short |
Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand |
title_full |
Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand |
title_fullStr |
Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand |
title_full_unstemmed |
Decoupling Between Phytoplankton Growth and Microzooplankton Grazing Enhances Productivity in Subantarctic Waters on Campbell Plateau, Southeast of New Zealand |
title_sort |
decoupling between phytoplankton growth and microzooplankton grazing enhances productivity in subantarctic waters on campbell plateau, southeast of new zealand |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://hal.science/hal-03859049 https://doi.org/10.1029/2019JC015550 |
long_lat |
ENVELOPE(171.000,171.000,-50.667,-50.667) ENVELOPE(173.132,173.132,52.801,52.801) |
geographic |
Southern Ocean Austral New Zealand Campbell Plateau Near Islands |
geographic_facet |
Southern Ocean Austral New Zealand Campbell Plateau Near Islands |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
ISSN: 2169-9275 EISSN: 2169-9291 Journal of Geophysical Research. Oceans https://hal.science/hal-03859049 Journal of Geophysical Research. Oceans, 2020, 125, ⟨10.1029/2019JC015550⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1029/2019JC015550 hal-03859049 https://hal.science/hal-03859049 BIBCODE: 2020JGRC.12515550G doi:10.1029/2019JC015550 |
op_doi |
https://doi.org/10.1029/2019JC015550 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
125 |
container_issue |
2 |
_version_ |
1798855238310952960 |