title: Growth form defines physiological photoprotective capacity in intertidal benthic diatoms.
abstract: In intertidal marine sediments, characterized by rapidly fluctuating and often extreme light conditions, primary production is frequently dominated by diatoms. We performed a comparative analysis of photophysiological traits in 15 marine benthic diatom species belonging to the four major morphological growth forms (epipelon (EPL), motile epipsammon (EPM-M) and non-motile epipsammon (EPM-NM) and tychoplankton (TYCHO)) found in these sediments. Our analyses revealed a clear relationship between growth form and photoprotective capacity, and identified fast regulatory physiological photoprotective traits (that is, non-photochemical quenching (NPQ) and the xanthophyll cycle (XC)) as key traits defining the functional light response of these diatoms. EPM-NM and motile EPL showed the highest and lowest NPQ, respectively, with EPM-M showing intermediate values. Like EPL, TYCHO had low NPQ, irrespective of whether they were grown in benthic or planktonic conditions, reflecting an adaptation to a low light environment. Our results thus provide the first experimental evidence for the existence of a trade-off between behavioural (motility) and physiological photoprotective mechanisms (NPQ and the XC) in the four major intertidal benthic diatoms growth forms using unialgal cultures. Remarkably, although motility is restricted to the raphid pennate diatom clade, raphid pennate species, which have adopted a non-motile epipsammic or a tychoplanktonic life style, display the physiological photoprotective response typical of these growth forms. This observation underscores the importance of growth form and not phylogenetic relatedness as the prime determinant shaping the physiological photoprotective capacity of benthic diatoms.
authors.affiliation: UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Barnett
authors.affiliation: 1] UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France [2] UPRES EA 2160 MMS 'Mer, Molécules, Santé', Université de Nantes, Faculté des Sciences et Techniques, Nantes Cedex 3, France.
authors.forename: Vona
authors.initials: V
authors.lastname: Méléder
authors.affiliation: 1] UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France [2] Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium.
authors.forename: Lander
authors.initials: L
authors.lastname: Blommaert
authors.affiliation: UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Lepetit
authors.affiliation: 1] UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France [2] UPRES EA 2160 MMS 'Mer, Molécules, Santé', Université de Nantes, Faculté des Sciences et Techniques, Nantes Cedex 3, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Gaudin
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vyverman
authors.affiliation: Laboratory of Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Sabbe
authors.affiliation: UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Dupuy
authors.affiliation: UMR7266 LIENSs 'Littoral, Environnement et Sociétés', CNRS/Université de La Rochelle, Institut du Littoral et de l'Environnement, La Rochelle, France.
authors.forename: Johann
authors.initials: J
authors.lastname: Lavaud
mesh_terms: D000064:Acclimatization; D017377:Diatoms / Q000254:growth & development / Q000378:metabolism*; D008027:Light; D010788:Photosynthesis / Q000502:physiology; D010802:Phylogeny; D010839:Phytoplankton / Q000254:growth & development; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D024341:Xanthophylls