Microscale imaging sheds light on species‐specific strategies for photo‐regulation and photo‐acclimation of microphytobenthic diatoms

Type Article
Date 2023-12
Language English
Author(s) Jesus BrunoORCID1, Jauffrais ThierryORCID2, 3, Trampe Erik4, Méléder Vona1, Ribeiro Lourenço5, Bernhard Joan M.6, Geslin Emmanuelle3, Kühl MichaelORCID4
Affiliation(s) 1 : Nantes Université, Institut des Substances et Organismes de la Mer, ISOMer, UR2160 Nantes, France
2 : Ifremer, IRD, Univ Nouvelle‐Calédonie Univ La Réunion, CNRS, UMR 9220 ENTROPIE, RBE/LEAD Noumea, New Caledonia
3 : Université d'Angers Nantes Université, Le Mans Université Angers, France
4 : Marine Biological Section, Department of Biology University of Copenhagen Helsingør ,Denmark
5 : MARE – Marine and Environmental Sciences Centre/ARNET – Aquatic Research Network Associated Laboratory, Faculty of Sciences University of Lisbon Lisbon ,Portugal
6 : Geology and Geophysics Department Woods Hole Oceanographic Institution Woods Hole Massachusetts, USA
Source Environmental Microbiology (1462-2912) (Wiley), 2023-12 , Vol. 25 , N. 12 , P. 3087-3103
DOI 10.1111/1462-2920.16499

Intertidal microphytobenthic (MPB) biofilms are key sites for coastal primary production, predominantly by pennate diatoms exhibiting photo‐regulation via non‐photochemical quenching (NPQ) and vertical migration. Movement is the main photo‐regulation mechanism of motile (epipelic) diatoms and because they can move from light, they show low‐light acclimation features such as low NPQ levels, as compared to non‐motile (epipsammic) forms. However, most comparisons of MPB species‐specific photo‐regulation have used low light acclimated monocultures, not mimicking environmental conditions. Here we used variable chlorophyll fluorescence imaging, fluorescent labelling in sediment cores and scanning electron microscopy to compare the movement and NPQ responses to light of four epipelic diatom species from a natural MPB biofilm. The diatoms exhibited different species‐specific photo‐regulation features and a large NPQ range, exceeding that reported for epipsammic diatoms. This could allow epipelic species to coexist in compacted light niches of MPB communities. We show that diatom cell orientation within MPB can be modulated by light, where diatoms oriented themselves more perpendicular to the sediment surface under high light vs. more parallel under low light, demonstrating behavioural, photo‐regulatory response by varying their light absorption cross‐section. This highlights the importance of considering species‐specific responses and understanding cell orientation and photo‐behaviour in MPB research.

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Publisher's official version 17 10 MB Open access
Figure S1. Workflow to quantify diatom pixels in relation to the sediment surface. Example of a portion of a HL sample. (A) FLEC image of a sediment profile used to manually draw the sediment ... 1 MB Open access
Figure S2. Example of a LL sediment profile sample processed for cell orientation analysis. White lines were drawn on top of the cells along ... 693 KB Open access
Figure S3. Sediment profile of a LL SEM image overlaid on the corresponding FLEC image. Overlaying these two types of images helped with the detection of the sediment surface. Sediment appears in ... 858 KB Open access
Table S1. PAM fluorescence parameters and nomenclature. 63 KB Open access
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Jesus Bruno, Jauffrais Thierry, Trampe Erik, Méléder Vona, Ribeiro Lourenço, Bernhard Joan M., Geslin Emmanuelle, Kühl Michael (2023). Microscale imaging sheds light on species‐specific strategies for photo‐regulation and photo‐acclimation of microphytobenthic diatoms. Environmental Microbiology, 25(12), 3087-3103. Publisher's official version : https://doi.org/10.1111/1462-2920.16499 , Open Access version : https://archimer.ifremer.fr/doc/00853/96459/