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

Ralph, PJ; Ryan, KG; Martin, A; Fenton, G

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

Ralph, PJ

Ryan, KG Martin, A Fenton, G

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Publication Type:: Journal Article
Citation:: Journal of Phycology, 2007, 43 (5), pp. 948 - 956
Issue Date:: 2007-10-01

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Field	Value	Language
dc.contributor.author	Ralph, PJ https://orcid.org/0000-0002-3103-7346	en_US
dc.contributor.author	Ryan, KG	en_US
dc.contributor.author	Martin, A	en_US
dc.contributor.author	Fenton, G	en_US
dc.date.issued	2007-10-01	en_US
dc.identifier.citation	Journal of Phycology, 2007, 43 (5), pp. 948 - 956	en_US
dc.identifier.issn	0022-3646	en_US
dc.identifier.uri	http://hdl.handle.net/10453/3856
dc.description.abstract	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. © 2007 Phycological Society of America.	en_US
dc.relation.ispartof	Journal of Phycology	en_US
dc.relation.isbasedon	10.1111/j.1529-8817.2007.00382.x	en_US
dc.subject.classification	Marine Biology & Hydrobiology	en_US
dc.title	Melting out of sea ice causes greater photosynthetic stress in algae than freezing in	en_US
dc.type	Journal Article
utslib.citation.volume	5	en_US
utslib.citation.volume	43	en_US
utslib.for	0607 Plant Biology	en_US
utslib.for	0704 Fisheries Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	closed_access
pubs.issue	5	en_US
pubs.publication-status	Published	en_US
pubs.volume	43	en_US

Abstract:

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. © 2007 Phycological Society of America.

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http://hdl.handle.net/10453/3856