Photoacclimation to abrupt changes in light intensity by Phaeodactylum tricornutum and Emiliania huxleyi: the role of calcification.

Barcelos e Ramos, Joana, Schulz, Kai G., Febiri, Sarah and Riebesell, Ulf (2012) Photoacclimation to abrupt changes in light intensity by Phaeodactylum tricornutum and Emiliania huxleyi: the role of calcification. Open Access Marine Ecology Progress Series, 452 . pp. 11-26. DOI 10.3354/meps09606.

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Abstract

Phytoplankton experience strong and abrupt variations in light intensity. How cells cope with these changes influences their competitiveness in a highly dynamical environment. While a considerable amount of work has focused on photoacclimation, it is still unknown whether processes specific of phytoplankton groups (e.g. calcification and silicification) influence their response to changing light. Here we show that the diatom Phaeodactylum tricornutum and the coccolithophore Emiliania huxleyi respond to an abrupt increase in irradiance by increasing carbon fixation rates, decreasing light absorption through the decrease of light-harvesting pigments and increasing energy dissipation through the xanthophyll cycle. In addition, E. huxleyi rapidly increases calcium carbonate precipitation in response to elevated light intensity, thereby providing an additional sink for excess energy. Differences between the 2 species also emerge with regard to the magnitude and timing of their individual responses. While E. huxleyi show a pronounced decrease in chlorophyll a and fucoxanthin cellular contents following increased light intensity, P. tricornutum has a faster increase in diadinoxanthin quota, a slower decrease in Fv/Fm (ratio of variable to maximum fluorescence) and a stronger increase in organic carbon fixation rate during the first 10 min. Our findings provide further evidence of species-specific responses to abrupt changes in light intensity, which may partly depend on the phytoplankton functional groups, with coccolithophores having a supplementary path (calcification) for the rapid dissipation of excess energy produced after an abrupt increase in light intensity. These differences might influence competition between coexisting species and may therefore have consequences at the community level.

Document Type: Article
Additional Information: WOS:000303213900002
Keywords: Calcification · Light · Coccolithophores · Diatoms · Phytoplankton · Pigments · Carbon fixation; PHOTOSYNTHETIC CARBON ASSIMILATION; MARINE DIATOM; XANTHOPHYLL-CYCLE; CONCENTRATING MECHANISMS; CHLOROPHYLL FLUORESCENCE; DIADINOXANTHIN CYCLE; PHYTOPLANKTON; PHOTOPROTECTION; GROWTH; CO2
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.3354/meps09606
ISSN: 0171-8630
Projects: DIATOMICS, Future Ocean
Date Deposited: 03 Dec 2012 13:50
Last Modified: 22 Jun 2018 10:06
URI: http://oceanrep.geomar.de/id/eprint/19485

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