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Comparative seasonal biogeography of mineralising nannoplankton in the Scotia Sea: Emiliania huxleyi, Fragilariopsis spp. and Tetraparma pelagica

Comparative seasonal biogeography of mineralising nannoplankton in the Scotia Sea: Emiliania huxleyi, Fragilariopsis spp. and Tetraparma pelagica
Comparative seasonal biogeography of mineralising nannoplankton in the Scotia Sea: Emiliania huxleyi, Fragilariopsis spp. and Tetraparma pelagica
The Southern Ocean is an important biogeochemical region on a global scale, in which mineralising phytoplankton play a role in cycling energy, carbon and nutrients. Mineralising phytoplankton with cells 2–20 ?m in diameter (nannoplankton) are poorly enumerated by traditional preservation and microscopy techniques, yet may fulfil an important role in the Southern Ocean. Here we define the spatial and temporal biogeography for these mineralising nannoplankton assessed by scanning electron microscopy in conjunction with an array of biological, physical, and chemical variables during two cruises to the Scotia Sea region of the Southern Ocean. The cruises encompassed two seasons, austral summer (January–February 2008) and austral autumn (March–April 2009).

The biogeography of the three most numerous mineralising nannoplankton groups, the coccolithophore Emiliania huxleyi, the smaller (<10 ?m) species of the diatom genus Fragilariopsis, and chrysophytes of the genus Tetraparma (mostly Tetraparma pelagica) were found to be related to the boundaries of the major circumpolar fronts. E. huxleyi abundances were relatively high in the northern water masses (maximum of 650 cells ml?1), while T. pelagica abundances were high in the southern water masses (maximum of 1910 cells ml?1). Small Fragilariopsis spp. abundances were also highest in the southern water masses (maximum of 1820 cells ml?1), but this group was present throughout the Scotia Sea.

Multivariate statistical analysis found that the most influential environmental variables controlling mineralising nannoplankton biogeography were sea surface temperature and silicate concentration. Estimates of biomass indicated that the Scotia Sea mineralising nannoplankton community formed a substantial part of the total phytoplankton community, particularly south of the Southern Antarctic Circumpolar Current Front (SACCF) during the austral autumn, where mineralising nannoplankton biomass reached 36% of the total phytoplankton biomass. The results that are obtained suggest that traditional microscopic surveys of large Southern Ocean phytoplankton may underestimate total biomass by excluding key mineralising nannoplankton groups. Greater appreciation of the ecological significance of mineralising nannoplankton in the Southern Ocean will improve our understanding of the relationships between environmental parameters, primary production, and the biological carbon pump in this ecosystem.
Southern Ocean, Scotia Sea, Diatoms, Nannoplankton, Biogeography, Coccolithophores
0967-0645
57-66
Hinz, D.J.
baa26745-8c24-465e-afc7-d2cd261d8a2d
Poulton, A.J.
14bf64a7-d617-4913-b882-e8495543e717
Nielsdóttir, M.C.
a2f4e879-340c-4e2a-985e-ac1112448164
Steigenberger, S.
15c989b8-dd0d-454c-b3cc-08d4290eaff0
Korb, R.E.
2180314d-28bc-4af8-9cda-09a570e64bc7
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9
Bibby, T.S.
e04ea079-dd90-4ead-9840-00882de27ebd
Hinz, D.J.
baa26745-8c24-465e-afc7-d2cd261d8a2d
Poulton, A.J.
14bf64a7-d617-4913-b882-e8495543e717
Nielsdóttir, M.C.
a2f4e879-340c-4e2a-985e-ac1112448164
Steigenberger, S.
15c989b8-dd0d-454c-b3cc-08d4290eaff0
Korb, R.E.
2180314d-28bc-4af8-9cda-09a570e64bc7
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9
Bibby, T.S.
e04ea079-dd90-4ead-9840-00882de27ebd

Hinz, D.J., Poulton, A.J., Nielsdóttir, M.C., Steigenberger, S., Korb, R.E., Achterberg, E.P. and Bibby, T.S. (2012) Comparative seasonal biogeography of mineralising nannoplankton in the Scotia Sea: Emiliania huxleyi, Fragilariopsis spp. and Tetraparma pelagica. Deep Sea Research Part II: Topical Studies in Oceanography, 59-60, 57-66. (doi:10.1016/j.dsr2.2011.09.002).

Record type: Article

Abstract

The Southern Ocean is an important biogeochemical region on a global scale, in which mineralising phytoplankton play a role in cycling energy, carbon and nutrients. Mineralising phytoplankton with cells 2–20 ?m in diameter (nannoplankton) are poorly enumerated by traditional preservation and microscopy techniques, yet may fulfil an important role in the Southern Ocean. Here we define the spatial and temporal biogeography for these mineralising nannoplankton assessed by scanning electron microscopy in conjunction with an array of biological, physical, and chemical variables during two cruises to the Scotia Sea region of the Southern Ocean. The cruises encompassed two seasons, austral summer (January–February 2008) and austral autumn (March–April 2009).

The biogeography of the three most numerous mineralising nannoplankton groups, the coccolithophore Emiliania huxleyi, the smaller (<10 ?m) species of the diatom genus Fragilariopsis, and chrysophytes of the genus Tetraparma (mostly Tetraparma pelagica) were found to be related to the boundaries of the major circumpolar fronts. E. huxleyi abundances were relatively high in the northern water masses (maximum of 650 cells ml?1), while T. pelagica abundances were high in the southern water masses (maximum of 1910 cells ml?1). Small Fragilariopsis spp. abundances were also highest in the southern water masses (maximum of 1820 cells ml?1), but this group was present throughout the Scotia Sea.

Multivariate statistical analysis found that the most influential environmental variables controlling mineralising nannoplankton biogeography were sea surface temperature and silicate concentration. Estimates of biomass indicated that the Scotia Sea mineralising nannoplankton community formed a substantial part of the total phytoplankton community, particularly south of the Southern Antarctic Circumpolar Current Front (SACCF) during the austral autumn, where mineralising nannoplankton biomass reached 36% of the total phytoplankton biomass. The results that are obtained suggest that traditional microscopic surveys of large Southern Ocean phytoplankton may underestimate total biomass by excluding key mineralising nannoplankton groups. Greater appreciation of the ecological significance of mineralising nannoplankton in the Southern Ocean will improve our understanding of the relationships between environmental parameters, primary production, and the biological carbon pump in this ecosystem.

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Published date: January 2012
Keywords: Southern Ocean, Scotia Sea, Diatoms, Nannoplankton, Biogeography, Coccolithophores
Organisations: Marine Biogeochemistry, Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 210497
URI: http://eprints.soton.ac.uk/id/eprint/210497
ISSN: 0967-0645
PURE UUID: b0974f96-4db5-4046-a566-bb33bb352014

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Date deposited: 09 Feb 2012 09:53
Last modified: 14 Mar 2024 04:48

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Contributors

Author: D.J. Hinz
Author: A.J. Poulton
Author: M.C. Nielsdóttir
Author: S. Steigenberger
Author: R.E. Korb
Author: E.P. Achterberg
Author: T.S. Bibby

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