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The role of coccoliths in protecting Emiliania huxleyi against stressful light and UV radiation

Citation

Xu, J and Bach, LT and Schulz, KG and Zhao, W and Gao, K and Riebesell, U, The role of coccoliths in protecting Emiliania huxleyi against stressful light and UV radiation, Biogeosciences, 13 pp. 4637-4643. ISSN 1726-4170 (2016) [Refereed Article]


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Copyright 2016 the authors. Licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0) https://creativecommons.org/licenses/by/3.0/

DOI: doi:10.5194/bg-13-4637-2016

Abstract

Coccolithophores are a group of phytoplankton species which cover themselves with small scales (coccoliths) made of calcium carbonate (CaCO3). The reason why coccolithophores form these calcite platelets has been a matter of debate for decades but has remained elusive so far. One hypothesis is that they play a role in light or UV protection, especially in surface dwelling species like Emiliania huxleyi, which can tolerate exceptionally high levels of solar radiation. In this study, we tested this hypothesis by culturing a calcified and a naked strain under different light conditions with and without UV radiation. The coccoliths of E. huxleyi reduced the transmission of visible radiation (400700 nm) by 7.5 %, that of UV-A (315400 nm) by 14.1 % and that of UV-B (280315 nm) by 18.4 %. Growth rates of the calcified strain (PML B92/11) were about 2 times higher than those of the naked strain (CCMP 2090) under indoor constant light levels in the absence of UV radiation. When exposed to outdoor conditions (fluctuating sunlight with UV radiation), growth rates of calcified cells were almost 3.5 times higher compared to naked cells. Furthermore, the relative electron transport rate was 114 % higher and non-photochemical quenching (NPQ) was 281 % higher in the calcified compared to the naked strain, implying higher energy transfer associated with higher NPQ in the presence of calcification. When exposed to natural solar radiation including UV radiation, the maximal quantum yield of photosystem II was only slightly reduced in the calcified strain but strongly reduced in the naked strain. Our results reveal an important role of coccoliths in mitigating light and UV stress in E. huxleyi.

Item Details

Item Type:Refereed Article
Keywords:coccolithophores, light, calcification
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological Oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
UTAS Author:Bach, LT (Dr Lennart Bach)
ID Code:133574
Year Published:2016
Web of Science® Times Cited:10
Deposited By:Ecology and Biodiversity
Deposited On:2019-07-02
Last Modified:2019-08-12
Downloads:2 View Download Statistics

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