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Response of Phytoplankton Photophysiology to Varying Environmental Conditions in the Sub-Antarctic and Polar Frontal Zone


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Cheah, W, McMinn, A, Griffiths, FB, Westwood, KJ, Wright, SW and Clementson, LA 2013 , 'Response of Phytoplankton Photophysiology to Varying Environmental Conditions in the Sub-Antarctic and Polar Frontal Zone' , PLOS One, vol. 8, no. 8 , pp. 1-13 , doi: 10.1371/journal.pone.0072165.

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Climate-driven changes are expected to alter the hydrography of the Sub-Antarctic Zone (SAZ) and Polar Frontal Zone (PFZ)
south of Australia, in which distinct regional environments are believed to be responsible for the differences in
phytoplankton biomass in these regions. Here, we report how the dynamic influences of light, iron and temperature, which
are responsible for the photophysiological differences between phytoplankton in the SAZ and PFZ, contribute to the
biomass differences in these regions. High effective photochemical efficiency of photosystem II (F
mw0.4), maximum
photosynthesis rate (PB
max), light-saturation intensity (Ek), maximum rate of photosynthetic electron transport (1/tPSII), and
low photoprotective pigment concentrations observed in the SAZ correspond to high chlorophyll a and iron
concentrations. In contrast, phytoplankton in the PFZ exhibits low F
m (* 0.2) and high concentrations of
photoprotective pigments under low light environment. Strong negative relationships between iron, temperature, and
photoprotective pigments demonstrate that cells were producing more photoprotective pigments under low temperature
and iron conditions, and are responsible for the low biomass and low productivity measured in the PFZ. As warming and
enhanced iron input is expected in this region, this could probably increase phytoplankton photosynthesis in this region.
However, complex interactions between the biogeochemical processes (e.g. stratification caused by warming could prevent
mixing of nutrients), which control phytoplankton biomass and productivity, remain uncertain.

Item Type: Article
Authors/Creators:Cheah, W and McMinn, A and Griffiths, FB and Westwood, KJ and Wright, SW and Clementson, LA
Journal or Publication Title: PLOS One
ISSN: 1932-6203
DOI / ID Number: 10.1371/journal.pone.0072165
Additional Information:

Copyright 2013 The Authors

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