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Scientific article
English

Iron-limitation and high light stress on phytoplankton populations from the Australian Sub-Antarctic Zone (SAZ)

Contributors

Petrou, Katherina; Hassler, Christel; Doblin, Martina A.; Shelly, Kirsten; Schoemann, Véronique; van den Enden, Rick; Wright, Simon; Ralph, Peter J.

Published in

Deep-sea research. Part 2. Topical studies in oceanography, vol. 58, no. 21-22, p. 2200-2211

Publication date

2011

Abstract

The high nutrient low chlorophyll (HNLC) surface waters of the Southern Ocean are characterised by high concentrations of nitrate and phosphate, low concentrations of dissolved iron and deep vertical mixing. Future climate scenarios predict increased surface temperatures and ocean stratification in the region. These changes to vertical mixing will result in a slowdown of nutrient supply to surface waters and an increase in the integrated irradiance in the upper mixed layer. To investigate the influence of iron-limitation and high irradiance on phytoplankton growth and physiology, a 6-day shipboard incubation experiment was conducted during the Sub-Antarctic Zone Sensitivity to Environmental Change (SAZ Sense) voyage using phytoplankton populations from the upper mixed layer in the north-eastern SAZ region. Iron-limitation was induced with an organic siderophore and was compared with a 1 nM iron-enriched incubation and an unamended treatment (under silicate replete conditions). As expected, iron enrichment led to dominance by large diatoms and enhanced photosynthetic performance, while the iron-limited community showed a decline in total chl a and photochemical efficiency. Under the added stress of high light, the iron-limited community was able to cope with the shift from in situ (<150 μmol photons m−2 s−1) to incubation (mean=765 μmol photons m−2 s−1) irradiance by increasing the proportion of photoprotective pigments and diverting excess light energy via energy-dependent quenching (qE). The responses to iron-limitation under high light showed that the phytoplankton community was able to acclimate to these conditions, but exhibited an overall decline in photosynthetic activity. Data presented here suggest the community shifts, in particular the decrease in diatoms, and the decline in photosynthetic performance of phytoplankton under low iron-high irradiance conditions has the potential to impact future ocean productivity and biogeochemical cycling.

Keywords

  • Light stress
  • Iron
  • Phytoplankton
  • Xanthophyll cycling
  • Southern Ocean

UNIGE affiliation entities

Not a UNIGE publication

Citation (ISO format)

PETROU, Katherina et al. Iron-limitation and high light stress on phytoplankton populations from the Australian Sub-Antarctic Zone (SAZ). In: Deep-sea research. Part 2. Topical studies in oceanography, 2011, vol. 58, n° 21-22, p. 2200–2211. doi: 10.1016/j.dsr2.2011.05.020

Main files (1)

Article (Published version)

Identifiers

Additional URL for this publication

http://linkinghub.elsevier.com/retrieve/pii/S0967064511001469

Journal ISSN

0967-0645
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Technical informations

Creation

21/01/2013 12:09:00

First validation

21/01/2013 12:09:00

Update

14/03/2023 19:59:23

Status update

14/03/2023 19:59:23

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