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Melting out of sea ice causes greater photosynthetic stress in algae than freezing in


Ralph, PJ and Ryan, KG and Martin, A and Fenton, G, Melting out of sea ice causes greater photosynthetic stress in algae than freezing in, Journal of Phycology, 43, (5) pp. 948-956. ISSN 0022-3646 (2007) [Refereed Article]

Copyright Statement

 2007, Crown Copyright

DOI: doi:10.1111/j.1529-8817.2007.00382.x


Sea ice is the dominant feature of polar oceans and contains significant quantities of microalgae. When sea ice forms and melts, the microalgal cells within the ice matrix are exposed to altered salinity and irradiance conditions, and subsequently, their photosynthetic apparatuses become stressed. To simulate the effect of ice formation and melting, samples of sea-ice algae from Cape Hallett (Antarctica) were exposed to altered salinity conditions and incubated under different levels of irradiance. The physiological condition of their photosynthetic apparatuses was monitored using fast and slow fluorescence-induction kinetics. Sea-ice algae exhibited the least photosynthetic stress when maintained in 35 and 51 salinity, whereas 16, 21, and 65 treatments resulted in significant photosynthetic stress. The greatest photosynthetic impact appeared on PSII, resulting in substantial closure of PSII reaction centers when exposed to extreme salinity treatments. Salinity stress to sea-ice algae was light dependent, such that incubated samples only suffered photosynthetic damage when irradiance was applied. Analysis of fast-induction curves showed reductions in J, I, and P transients (or steps) associated with combined salinity and irradiance stress. This stress manifests itself in the limited capacity for the reduction of the primary electron receptor, QA, and the plastoquinone pool, which ultimately inhibited effective quantum yield of PSII and electron transport rate. These results suggest that sea-ice algae undergo greater photosynthetic stress during the process of melting into the hyposaline meltwater lens at the ice edge during summer than do microalgae cells during their incorporation into the ice matrix during the process of freezing.

Item Details

Item Type:Refereed Article
Keywords:fluorescence, PAM, PEA
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Mycology
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:102949
Year Published:2007
Web of Science® Times Cited:48
Deposited By:IMAS Research and Education Centre
Deposited On:2015-09-11
Last Modified:2015-10-06

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