title: Grazing-induced changes in cell wall silicification in a marine diatom.
abstract: In aquatic environments, diatoms (Bacillariophyceae) constitute a central group of microalgae which contribute to about 40% of the oceanic primary production. Diatoms have an absolute requirement for silicon to build-up their silicified cell wall in the form of two shells (the frustule). To date, changes in diatom cell wall silicification have been only studied in response to changes in the growth environment, with consistent increase in diatom silica content when specific growth rates decrease under nutrient or light limitations. Here, we report the first evidence for grazing-induced changes in cell wall silicification in a marine diatom. Cells grown in preconditioned media that had contained both diatoms and herbivores are significantly more silicified than diatoms grown in media that have contained diatoms alone or starved herbivores. These observations suggest that grazing-induced increase in cell wall silicification can be viewed as an adaptive reaction in habitats with variable grazing pressure, and demonstrate that silicification in diatoms is not only a constitutive mechanical protection for the cell, but also a phenotypically plastic trait modulated by grazing. In turn, our results corroborate the idea that plant-herbivore interactions, beyond grazing sensu stricto, contribute to drive ecosystem structure and biogeochemical cycles in the ocean.
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin, LEMAR, UMR UBO-CNRS 6539, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Place Nicolas Copernic, 29280 Plouzané, France. Philippe.Pondaven@univ.brest.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Pondaven
authors.forename: Morgane
authors.initials: M
authors.lastname: Gallinari
authors.forename: Sophie
authors.initials: S
authors.lastname: Chollet
authors.forename: Eva
authors.initials: E
authors.lastname: Bucciarelli
authors.forename: Géraldine
authors.initials: G
authors.lastname: Sarthou
authors.forename: Sabine
authors.initials: S
authors.lastname: Schultes
authors.forename: Frédéric
authors.initials: F
authors.lastname: Jean
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D033342:Copepoda / Q000502:physiology*; D017377:Diatoms / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D017753:Ecosystem; D008386:Marine Biology; D011235:Predatory Behavior; D012822:Silicon Dioxide / Q000378:metabolism*
chemical_list: D012822:Silicon Dioxide