AME 52:223-232 (2008)  -  DOI:

Migration or photoacclimation to prevent high irradiance and UV-B damage in marine microphytobenthic communities

Jean-Luc Mouget1,*, Rupert Perkins2, Mireille Consalvey3, Sébastien Lefebvre4

1Laboratoire de Physiologie et de Biochimie végétales, Faculté des Sciences, Université du Maine, Av. O. Messiaen,
72085 Le Mans Cedex 9, France
2School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3YE, UK
3National Institute of Water and Atmospheric Research, Private Bag 14–901, Wellington, New Zealand
4UMR 100 IFREMER-UCBN, ‘Physiologie et écophysiologie des mollusques marins’, Laboratoire de Biologie et Biotechnologies Marines, Université de Caen, Esplanade de la paix, 14032 Caen Cedex, France

ABSTRACT: Microphytobenthos (MPB) on intertidal mudflats is a major component of primary producers in some estuarine ecosystems. To sustain photosynthesis, MPB migrate through the upper sediment layer and form transient biofilms during emersion periods, and thus may be exposed to high irradiance and ultraviolet radiation (UV-R), possibly resulting in photodamage to the photosynthetic apparatus. In contrast, downard migration could allow cells to optimize position in the photic zone, avoiding photoinhibitory light levels. Engineered biofilms with inhibited migratory capacity were used to distinguish between possible strategies (photoacclimation or migration) evolved by MPB to cope with photoinhibitory irradiances, when a series of UV filters with different cut-off wavelengths was used to estimate the respective contribution of visible light and UV-R. Engineered biofilms with full migratory capacity maintained a high relative electron transport rate (rETR), in contrast to engineered non-migratory biofilms, which showed a decrease in rETR under high irradiance, with a greater decrease under UV-B radiation. Migration thus appeared to be the principal short-term mechanism allowing MPB to avoid or minimize UV-R and high PAR photodamage in situ. Nevertheless, physiological acclimation processes to different light levels (‘light-shade’ patterns) seem to occur in the long term, and probably superimpose on migratory capacity, making light history an important component of MPB photoacclimation strategies.

KEY WORDS: Microphytobenthos · Migration · Photodamage · Photoinhibition · Ultraviolet radiation

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Cite this article as: Mouget JL, Perkins R, Consalvey M, Lefebvre S (2008) Migration or photoacclimation to prevent high irradiance and UV-B damage in marine microphytobenthic communities. Aquat Microb Ecol 52:223-232.

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