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The short-term effect of irradiance on the photosynthetic properties of Antarctic fast-ice microalgal communities


Ryan, KG and Cowie, ROM and Liggins, E and McNaughtan, D and Martin, A, The short-term effect of irradiance on the photosynthetic properties of Antarctic fast-ice microalgal communities, Journal of Phycology, 45, (6) pp. 1290-1298. ISSN 0022-3646 (2009) [Refereed Article]

Copyright Statement

Copyright 2009 Phycological Society of America

DOI: doi:10.1111/j.1529-8817.2009.00764.x


Although sea-ice represents a harsh physicochemical environment with steep gradients in temperature, light, and salinity, diverse microbial communities are present within the ice matrix. We describe here the photosynthetic responses of sea-ice microalgae to varying irradiances. Rapid light curves (RLCs) were generated using pulse amplitude fluorometry and used to derive photosynthetic yield (ΦPSII), photosynthetic efficiency (α), and the irradiance (Ek) at which relative electron transport rate (rETR) saturates. Surface brine algae from near the surface and bottom-ice algae were exposed to a range of irradiances from 7 to 262 μmol photons · m−2 · s−1. In surface brine algae, ΦPSII and α remained constant at all irradiances, and rETRmax peaked at 151 μmol photons · m−2 · s−1, indicating these algae are well acclimated to the irradiances to which they are normally exposed. In contrast, ΦPSII, α, and rETRmax in bottom-ice algae reduced when exposed to irradiances >26 μmol photons · m−2 · s−1, indicating a high degree of shade acclimation. In addition, the previous light history had no significant effect on the photosynthetic capacity of bottom-ice algae whether cells were gradually exposed to target irradiances over a 12 h period or were exposed immediately (light shocked). These findings indicate that bottom-ice algae are photoinhibited in a dose-dependent manner, while surface brine algae tolerate higher irradiances. Our study shows that sea-ice algae are able to adjust to changes in irradiance rapidly, and this ability to acclimate may facilitate survival and subsequent long-term acclimation to the postmelt light regime of the Southern Ocean.

Item Details

Item Type:Refereed Article
Keywords:Anatarctic sea ice, PAM fluorometry, photoinhibition, rapid light curves
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial ecology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the biological sciences
UTAS Author:Martin, A (Dr Andrew Martin)
ID Code:102947
Year Published:2009
Web of Science® Times Cited:16
Deposited By:IMAS Research and Education Centre
Deposited On:2015-09-11
Last Modified:2015-10-06

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