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Nutrient regimes control phytoplankton ecophysiology in the South Atlantic

Nutrient regimes control phytoplankton ecophysiology in the South Atlantic
Nutrient regimes control phytoplankton ecophysiology in the South Atlantic
Fast Repetition Rate fluorometry (FRRf) measurements of phytoplankton photophysiology from an acrossbasin South Atlantic cruise (as part of the GEOTRACES programme) characterised two dominant ecophysiological regimes which were interpreted on the basis of nutrient limitation. South of the South Subtropical Convergence (SSTC) in the northern sub-Antarctic sector of the Antarctic Circumpolar Current (ACC) in the Eastern Atlantic Basin, waters are characterised by elevated chlorophyll concentrations, a dominance by larger phytoplankton cells, and low apparent photochemical efficiency (Fv / Fm). Shipboard 24 h iron (Fe) addition incubation experiments confirmed that Fe stress was primarily responsible for the low Fv / Fm, with Fe addition to these waters, either within the artificial bottle additions or naturally occurring downstream enrichment from Gough Island, significantly increasing Fv / Fm values. To the north of the SSTC at the southern boundary of the South Atlantic Gyre, phytoplankton are characterised by high values of Fv / Fm which, coupled with the low macronutrient concentrations and increased presence of picocyanobacteria, are interpreted as conditions of Fe replete, balanced macronutrient-limited growth. Spatial correlation was found between Fv / Fm and Fe:nitrate ratios, supporting the suggestion that the relative supply ratios of these two nutrients can control patterns of limitation and consequently the ecophysiology of phytoplankton in subtropical gyre and ACC regimes.
1726-4170
463-479
Browning, T.J.
0158e7b6-6096-4b75-a8a7-2b2f0b8b59e0
Bouman, H.A.
28b8c54e-3365-43a5-89ed-16ae62bcaf1e
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Schlosser, C.
7990a0cc-cfe9-4dd5-9c45-899c03186207
Tarran, G.A.
c6e9fb51-321c-4fb6-a2b0-00a58c344d73
Woodward, E.M.S.
3ac3b98f-78c7-4b43-acf9-bba3253752b5
Henderson, G.M.
1a310365-c407-4667-a617-b8473505a536
Browning, T.J.
0158e7b6-6096-4b75-a8a7-2b2f0b8b59e0
Bouman, H.A.
28b8c54e-3365-43a5-89ed-16ae62bcaf1e
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Schlosser, C.
7990a0cc-cfe9-4dd5-9c45-899c03186207
Tarran, G.A.
c6e9fb51-321c-4fb6-a2b0-00a58c344d73
Woodward, E.M.S.
3ac3b98f-78c7-4b43-acf9-bba3253752b5
Henderson, G.M.
1a310365-c407-4667-a617-b8473505a536

Browning, T.J., Bouman, H.A., Moore, C.M., Schlosser, C., Tarran, G.A., Woodward, E.M.S. and Henderson, G.M. (2014) Nutrient regimes control phytoplankton ecophysiology in the South Atlantic. Biogeosciences, 11 (2), 463-479. (doi:10.5194/bg-11-463-2014).

Record type: Article

Abstract

Fast Repetition Rate fluorometry (FRRf) measurements of phytoplankton photophysiology from an acrossbasin South Atlantic cruise (as part of the GEOTRACES programme) characterised two dominant ecophysiological regimes which were interpreted on the basis of nutrient limitation. South of the South Subtropical Convergence (SSTC) in the northern sub-Antarctic sector of the Antarctic Circumpolar Current (ACC) in the Eastern Atlantic Basin, waters are characterised by elevated chlorophyll concentrations, a dominance by larger phytoplankton cells, and low apparent photochemical efficiency (Fv / Fm). Shipboard 24 h iron (Fe) addition incubation experiments confirmed that Fe stress was primarily responsible for the low Fv / Fm, with Fe addition to these waters, either within the artificial bottle additions or naturally occurring downstream enrichment from Gough Island, significantly increasing Fv / Fm values. To the north of the SSTC at the southern boundary of the South Atlantic Gyre, phytoplankton are characterised by high values of Fv / Fm which, coupled with the low macronutrient concentrations and increased presence of picocyanobacteria, are interpreted as conditions of Fe replete, balanced macronutrient-limited growth. Spatial correlation was found between Fv / Fm and Fe:nitrate ratios, supporting the suggestion that the relative supply ratios of these two nutrients can control patterns of limitation and consequently the ecophysiology of phytoplankton in subtropical gyre and ACC regimes.

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Published date: 30 January 2014
Organisations: Ocean and Earth Science

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Local EPrints ID: 369264
URI: http://eprints.soton.ac.uk/id/eprint/369264
ISSN: 1726-4170
PURE UUID: f8bd4f6e-e1fc-4c2c-92aa-2d59c2daf5be

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Date deposited: 23 Sep 2014 09:40
Last modified: 15 Jul 2019 21:43

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