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Biogeographical patterns and environmental controls of phytoplankton communities from contrasting hydrographical zones of the Labrador Sea

Biogeographical patterns and environmental controls of phytoplankton communities from contrasting hydrographical zones of the Labrador Sea
Biogeographical patterns and environmental controls of phytoplankton communities from contrasting hydrographical zones of the Labrador Sea
The Labrador Sea is an important oceanic sink for atmospheric CO2 because of intensive convective mixing during winter and extensive phytoplankton blooms that occur during spring and summer. Therefore, a broad-scale investigation of the responses of phytoplankton community composition to environmental forcing is essential for understanding planktonic food-web organisation and biogeochemical functioning in the Labrador Sea. Here, we investigated the phytoplankton community structure (>4 ?m) from near surface blooms (<50 m) from spring and early summer (2011–2014) in detail, including species composition and environmental controls. Spring blooms (>1.2 mg chla m?3) occurred on and near the shelves in May and in offshore waters of the central Labrador Sea in June due to haline- and thermal-stratification, respectively. Sea ice-related (Fragilariopsis cylindrus and F. oceanica) and Arctic diatoms (Fossula arctica, Bacterosira bathyomphala and Thalassiosira hyalina) dominated the relatively cold (<0 °C) and fresh (salinity < 33) waters over the Labrador shelf (e.g., on the southwestern side of the Labrador Sea), where sea-ice melt and Arctic outflow predominates. On the northeastern side of the Labrador Sea, intense blooms of the colonial prymnesiophyte Phaeocystis pouchetii and diatoms, such as Thalassiosira nordenskioeldii, Pseudo-nitzschia granii and Chaetoceros socialis, occurred in the lower nutrient waters (nitrate < 3.6 ?M) of the West Greenland Current. The central Labrador Sea bloom occurred later in the season (June) and was dominated by Atlantic diatoms, such as Ephemera planamembranacea and Fragilariopsis atlantica. The data presented here demonstrate that the Labrador Sea spring and early summer blooms are composed of contrasting phytoplankton communities, for which taxonomic segregation appears to be controlled by the physical and biogeochemical characteristics of the dominant water masses.
0079-6611
212-226
Fragoso, Glaucia M.
406a23cd-79a7-430b-9dc5-9b98676b7f0f
Poulton, Alex J.
14bf64a7-d617-4913-b882-e8495543e717
Yashayaev, Igor M.
8b15c3c3-4f86-465b-ac7d-b8bc525c61d0
Head, Erica J.H.
b1eddcbe-b644-4ef0-a113-ab92f16860cd
Stinchcombe, Mark C.
433dd398-15f7-4730-9f1e-992d65bec70b
Purdie, Duncan A.
18820b32-185a-467a-8019-01f245191cd8
Fragoso, Glaucia M.
406a23cd-79a7-430b-9dc5-9b98676b7f0f
Poulton, Alex J.
14bf64a7-d617-4913-b882-e8495543e717
Yashayaev, Igor M.
8b15c3c3-4f86-465b-ac7d-b8bc525c61d0
Head, Erica J.H.
b1eddcbe-b644-4ef0-a113-ab92f16860cd
Stinchcombe, Mark C.
433dd398-15f7-4730-9f1e-992d65bec70b
Purdie, Duncan A.
18820b32-185a-467a-8019-01f245191cd8

Fragoso, Glaucia M., Poulton, Alex J., Yashayaev, Igor M., Head, Erica J.H., Stinchcombe, Mark C. and Purdie, Duncan A. (2016) Biogeographical patterns and environmental controls of phytoplankton communities from contrasting hydrographical zones of the Labrador Sea. Progress in Oceanography, 141, 212-226. (doi:10.1016/j.pocean.2015.12.007).

Record type: Article

Abstract

The Labrador Sea is an important oceanic sink for atmospheric CO2 because of intensive convective mixing during winter and extensive phytoplankton blooms that occur during spring and summer. Therefore, a broad-scale investigation of the responses of phytoplankton community composition to environmental forcing is essential for understanding planktonic food-web organisation and biogeochemical functioning in the Labrador Sea. Here, we investigated the phytoplankton community structure (>4 ?m) from near surface blooms (<50 m) from spring and early summer (2011–2014) in detail, including species composition and environmental controls. Spring blooms (>1.2 mg chla m?3) occurred on and near the shelves in May and in offshore waters of the central Labrador Sea in June due to haline- and thermal-stratification, respectively. Sea ice-related (Fragilariopsis cylindrus and F. oceanica) and Arctic diatoms (Fossula arctica, Bacterosira bathyomphala and Thalassiosira hyalina) dominated the relatively cold (<0 °C) and fresh (salinity < 33) waters over the Labrador shelf (e.g., on the southwestern side of the Labrador Sea), where sea-ice melt and Arctic outflow predominates. On the northeastern side of the Labrador Sea, intense blooms of the colonial prymnesiophyte Phaeocystis pouchetii and diatoms, such as Thalassiosira nordenskioeldii, Pseudo-nitzschia granii and Chaetoceros socialis, occurred in the lower nutrient waters (nitrate < 3.6 ?M) of the West Greenland Current. The central Labrador Sea bloom occurred later in the season (June) and was dominated by Atlantic diatoms, such as Ephemera planamembranacea and Fragilariopsis atlantica. The data presented here demonstrate that the Labrador Sea spring and early summer blooms are composed of contrasting phytoplankton communities, for which taxonomic segregation appears to be controlled by the physical and biogeochemical characteristics of the dominant water masses.

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Fragoso revised+Fig+Table 17dec2015.docx.pdf - Accepted Manuscript
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Accepted/In Press date: 18 December 2015
e-pub ahead of print date: 5 January 2016
Published date: 2016
Organisations: Ocean and Earth Science, Marine Biogeochemistry

Identifiers

Local EPrints ID: 387987
URI: http://eprints.soton.ac.uk/id/eprint/387987
ISSN: 0079-6611
PURE UUID: b8314c62-27ad-489c-8766-1e3c406d406f
ORCID for Duncan A. Purdie: ORCID iD orcid.org/0000-0001-6672-1722

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Date deposited: 17 Feb 2016 10:25
Last modified: 10 Jan 2022 02:32

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Contributors

Author: Glaucia M. Fragoso
Author: Alex J. Poulton
Author: Igor M. Yashayaev
Author: Erica J.H. Head
Author: Mark C. Stinchcombe

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