Melting out of sea ice causes greater photosynthetic stress in algae than freezing in
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. T...
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ftunivtsydney:oai:opus.lib.uts.edu.au:10453/3856 2023-05-15T13:58:39+02:00 Melting out of sea ice causes greater photosynthetic stress in algae than freezing in Ralph, PJ Ryan, KG Martin, A Fenton, G 2007-10-01 application/pdf http://hdl.handle.net/10453/3856 unknown Journal of Phycology 10.1111/j.1529-8817.2007.00382.x Journal of Phycology, 2007, 43 (5), pp. 948 - 956 0022-3646 http://hdl.handle.net/10453/3856 Marine Biology & Hydrobiology Journal Article 2007 ftunivtsydney 2022-03-13T13:31:39Z 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. Article in Journal/Newspaper Antarc* Antarctica ice algae Sea ice University of Technology Sydney: OPUS - Open Publications of UTS Scholars Hallett ENVELOPE(170.217,170.217,-72.317,-72.317) Cape Hallett ENVELOPE(170.217,170.217,-72.317,-72.317) |
institution |
Open Polar |
collection |
University of Technology Sydney: OPUS - Open Publications of UTS Scholars |
op_collection_id |
ftunivtsydney |
language |
unknown |
topic |
Marine Biology & Hydrobiology |
spellingShingle |
Marine Biology & Hydrobiology Ralph, PJ Ryan, KG Martin, A Fenton, G Melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
topic_facet |
Marine Biology & Hydrobiology |
description |
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. |
format |
Article in Journal/Newspaper |
author |
Ralph, PJ Ryan, KG Martin, A Fenton, G |
author_facet |
Ralph, PJ Ryan, KG Martin, A Fenton, G |
author_sort |
Ralph, PJ |
title |
Melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
title_short |
Melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
title_full |
Melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
title_fullStr |
Melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
title_full_unstemmed |
Melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
title_sort |
melting out of sea ice causes greater photosynthetic stress in algae than freezing in |
publishDate |
2007 |
url |
http://hdl.handle.net/10453/3856 |
long_lat |
ENVELOPE(170.217,170.217,-72.317,-72.317) ENVELOPE(170.217,170.217,-72.317,-72.317) |
geographic |
Hallett Cape Hallett |
geographic_facet |
Hallett Cape Hallett |
genre |
Antarc* Antarctica ice algae Sea ice |
genre_facet |
Antarc* Antarctica ice algae Sea ice |
op_relation |
Journal of Phycology 10.1111/j.1529-8817.2007.00382.x Journal of Phycology, 2007, 43 (5), pp. 948 - 956 0022-3646 http://hdl.handle.net/10453/3856 |
_version_ |
1766266998813097984 |