THE SHORT-TERM EFFECT OF IRRADIANCE ON THE PHOTOSYNTHETIC PROPERTIES OF ANTARCTIC FAST-ICE MICROALGAL COMMUNITIES(1).

• Published in: Journal of Phycology
• Main Authors: Ryan KG, Cowie ROM, Liggins E, McNaughtan D, Martin A, Davy SK
• Format: Article in Journal/Newspaper
• Language: English
• Published: WILEY-BLACKWELL PUBLISHING, INC 2009
• Subjects: Science & Technology; Life Sciences & Biomedicine; Plant Sciences; Marine & Freshwater Biology; Antarctic sea ice; E(k); PAM fluorometry; photoinhibition; rapid light curves; rETR(max); alpha; Theta(PSII); SEA-ICE; MCMURDO-SOUND; PRIMARY PRODUCTIVITY; ALGAL COMMUNITIES; PHOTOSYSTEM-II; D1 PROTEIN; PHOTOADAPTATION; PHOTOINACTIVATION; PHOTOPROTECTION; 0607 Plant Biology; 0704 Fisheries Sciences; Antarctic; McMurdo Sound; Southern Ocean; Antarc*; ice algae; Sea ice
• Online Access: http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000272837600007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=c5bb3b2499afac691c2e3c1a83ef6fef; https://doi.org/10.1111/j.1529-8817.2009.00764.x

CAUL read and publish agreement 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. Published