The University of Southampton
University of Southampton Institutional Repository

Physiological state of phytoplankton communities in the southwest Atlantic sector of the Southern Ocean, as measured by fast repetition rate fluorometry

Physiological state of phytoplankton communities in the southwest Atlantic sector of the Southern Ocean, as measured by fast repetition rate fluorometry
Physiological state of phytoplankton communities in the southwest Atlantic sector of the Southern Ocean, as measured by fast repetition rate fluorometry
The majority of the Southern Ocean is a high-nutrient low-chlorophyll (HNLC) ecosystem. Localized increases in chlorophyll concentration measured in the wake of bathymetric features near South Georgia demonstrate variations in the factors governing the HNLC condition. We explore the possibility that the contrast between these areas of high-chlorophyll and surrounding HNLC areas is associated with variations in phytoplankton photophysiology. Total dissolvable iron concentrations, phytoplankton photophysiology and community structure were investigated in late April 2003 on a transect along the North Scotia Ridge (53–54S) between the Falkland Islands and South Georgia (58–33W). Total dissolvable iron concentrations suggested a benthic source of iron near South Georgia. Bulk community measurements of dark-adapted photochemical quantum efficiency (Fv/Fm) exhibited a sharp increase to the east of 46W coincident with a decrease in the functional absorption cross-section (rPSII). Phytoplankton populations east of 46W thus displayed no physiological symptoms of iron or nitrate stress. Contrasting low Fv/Fm west of 46W could not be explained by variations in the macronutrients nitrate and silicic acid and may be the result of taxon specific variability in photophysiology or iron stress. We hypothesize that increased Fv/Fm resulted from local relief from iron stress near South Georgia, east of Aurora Bank, an area previously speculated to be a "pulse point" source of iron. Our measurements provide one of the first direct physiological confirmations that iron stress is alleviated in phytoplankton populations near South Georgia.
0722-4060
44-52
Holeton, C.L.
0492e0c7-e43a-4e29-be80-75555775d6c3
Nedelec, F.
60a34fde-bc21-4fed-968e-ca0f13435f7a
Sanders, R.
02c163c1-8f5e-49ad-857c-d28f7da66c65
Brown, L.
71ebbeab-98c3-45f3-b3f2-200387870709
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Stevens, D.P.
9b78fd18-9ea2-409d-b78f-61ac70555905
Heywood, K.J.
4eeebe72-3857-4729-8d6a-7ece46d37cd5
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Lucas, C.H.
521743e3-b250-4c6b-b084-780af697d6bf
Holeton, C.L.
0492e0c7-e43a-4e29-be80-75555775d6c3
Nedelec, F.
60a34fde-bc21-4fed-968e-ca0f13435f7a
Sanders, R.
02c163c1-8f5e-49ad-857c-d28f7da66c65
Brown, L.
71ebbeab-98c3-45f3-b3f2-200387870709
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Stevens, D.P.
9b78fd18-9ea2-409d-b78f-61ac70555905
Heywood, K.J.
4eeebe72-3857-4729-8d6a-7ece46d37cd5
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Lucas, C.H.
521743e3-b250-4c6b-b084-780af697d6bf

Holeton, C.L., Nedelec, F., Sanders, R., Brown, L., Moore, C.M., Stevens, D.P., Heywood, K.J., Statham, P.J. and Lucas, C.H. (2006) Physiological state of phytoplankton communities in the southwest Atlantic sector of the Southern Ocean, as measured by fast repetition rate fluorometry. Polar Biology, 29 (1), 44-52. (doi:10.1007/s00300-005-0028-y).

Record type: Article

Abstract

The majority of the Southern Ocean is a high-nutrient low-chlorophyll (HNLC) ecosystem. Localized increases in chlorophyll concentration measured in the wake of bathymetric features near South Georgia demonstrate variations in the factors governing the HNLC condition. We explore the possibility that the contrast between these areas of high-chlorophyll and surrounding HNLC areas is associated with variations in phytoplankton photophysiology. Total dissolvable iron concentrations, phytoplankton photophysiology and community structure were investigated in late April 2003 on a transect along the North Scotia Ridge (53–54S) between the Falkland Islands and South Georgia (58–33W). Total dissolvable iron concentrations suggested a benthic source of iron near South Georgia. Bulk community measurements of dark-adapted photochemical quantum efficiency (Fv/Fm) exhibited a sharp increase to the east of 46W coincident with a decrease in the functional absorption cross-section (rPSII). Phytoplankton populations east of 46W thus displayed no physiological symptoms of iron or nitrate stress. Contrasting low Fv/Fm west of 46W could not be explained by variations in the macronutrients nitrate and silicic acid and may be the result of taxon specific variability in photophysiology or iron stress. We hypothesize that increased Fv/Fm resulted from local relief from iron stress near South Georgia, east of Aurora Bank, an area previously speculated to be a "pulse point" source of iron. Our measurements provide one of the first direct physiological confirmations that iron stress is alleviated in phytoplankton populations near South Georgia.

This record has no associated files available for download.

More information

Published date: 2006

Identifiers

Local EPrints ID: 19282
URI: http://eprints.soton.ac.uk/id/eprint/19282
ISSN: 0722-4060
PURE UUID: 17bc03a0-8789-4245-975b-ef78d2133414
ORCID for C.M. Moore: ORCID iD orcid.org/0000-0002-9541-6046
ORCID for C.H. Lucas: ORCID iD orcid.org/0000-0002-5929-7481

Catalogue record

Date deposited: 30 Jan 2006
Last modified: 16 Mar 2024 03:10

Export record

Altmetrics

Contributors

Author: C.L. Holeton
Author: F. Nedelec
Author: R. Sanders
Author: L. Brown
Author: C.M. Moore ORCID iD
Author: D.P. Stevens
Author: K.J. Heywood
Author: P.J. Statham
Author: C.H. Lucas ORCID iD

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×