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Limitation of dimethylsulfoniopropionate synthesis at high irradiance in natural phytoplankton communities of the Tropical Atlantic

Archer, SD and Stefels, J and Airs, RL and Lawson, T and Smyth, TJ and Rees, AP and Geider, RJ (2018) 'Limitation of dimethylsulfoniopropionate synthesis at high irradiance in natural phytoplankton communities of the Tropical Atlantic.' Limnology and Oceanography, 63 (1). 227 - 242. ISSN 0024-3590

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Abstract

Predictions of the ocean-atmosphere flux of dimethyl sulfide will be improved by understanding what controls seasonal and regional variations in dimethylsulfoniopropionate (DMSP) production. To investigate the influence of high levels of irradiance including ultraviolet radiation (UVR), on DMSP synthesis rates (μDMSP) and inorganic carbon fixation (μPOC) by natural phytoplankton communities, nine experiments were carried out at different locations in the low nutrient, high light environment of the northeastern Tropical Atlantic. Rates of μDMSP and μPOC were determined by measuring the incorporation of inorganic 13C into DMSP and particulate organic carbon. Based on measurements over discrete time intervals during the day, a unique μDMSP vs. irradiance (P vs. E) relationship was established. Comparison is made with the P vs. E relationship for μPOC, indicating that light saturation of μDMSP occurs at similar irradiance to μPOC and is closely coupled to carbon fixation on a diel basis. Photoinhibition during the middle of the day was exacerbated by exposure to UVR, causing an additional 55–60% inhibition of both μDMSP and μPOC at the highest light levels. In addition, decreased production of DMSP in response to UVR-induced photoxidative stress, contrasted with the increased net synthesis of photoprotective xanthophyll pigments. Together these results indicate that DMSP production by phytoplankton in the tropical ocean is not regulated in the short term by the necessity to control increasing photooxidative stress as irradiance increases during the day. The study provides new insight into the regulation of resource allocation into this biogeochemically important, multi-functional compatible solute.

Item Type: Article
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 08 Mar 2018 12:42
Last Modified: 07 Aug 2019 21:15
URI: http://repository.essex.ac.uk/id/eprint/21262

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