Title :

Photosynthesis of Laminaria digitata during the immersion and emersion periods of spring tidal cycles during hot, sunny weather

Author(s) :

Migné, Aline [Auteur]
Adaptation et diversité en milieu marin [AD2M]
Delebecq, Gaspard [Auteur]
Davoult, Dominique [Auteur]
Spilmont, Nicolas [Auteur]
Menu, Dominique [Auteur]
Janquin, Marie-Andrée [Auteur]
Gevaert, Francois [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]

Journal title :

Cahiers de Biologie Marine

Pages :

143-155

Publisher :

Station Biologique de Roscoff

Publication date :

2021-01-22

ISSN :

0007-9723

HAL domain(s) :

Sciences du Vivant [q-bio]

English abstract : [en]

The boreal kelp Laminaria digitata dominates the low intertidal and upper subtidal zones of moderately exposed rocky shores in northwestern Europe. Due to ocean warming, this foundation species is predicted to disappear ...
Show more >The boreal kelp Laminaria digitata dominates the low intertidal and upper subtidal zones of moderately exposed rocky shores in northwestern Europe. Due to ocean warming, this foundation species is predicted to disappear from French coasts in the near future. Photosynthesis of L. digitata sporophytes was surveyed in situ during spring and summer tidal cycles with emersion periods around midday during hot, sunny weather. The net production (NP) of whole individuals (i.e. the difference between their gross primary production and respiration) was assessed by measuring carbon fluxes inside a closed chamber. Photosynthetic performance of thalli was assessed using pulse-amplitude modulated (PAM) fluorescence parameters, the effective (Φ PSII) and optimal (F V /F M) quantum yields of photosystem II. Content in pigments involved in the xanthophyll cycle, a photoprotective mechanism, was measured in thalli to evaluate the de-epoxidation ratio (DR). NP shifted from positive values (reaching 140 μmol C g DW-1 h-1) during morning immersion to negative values during emersion (reaching-37 μmol C g DW-1 h-1), and did not return to positive values during the following immersion period when respiration was exacerbated. Φ PSII decreased during emersion (down to 0.01), but recovered during afternoon immersion. F V /F M decreased during emersion (down to 0.18) indicating severe photoinhibition. High DR values (up to 0.70) showed the effectiveness of the photoprotective mechanism, which appeared nevertheless insufficient to prevent photodamage during emersion stress. Among the environmental factors contributing to this emersion stress, repeated heat shocks over consecutive tide cycles likely play a leading role. These repeated heat shocks appear to further exacerbate the detrimental effects of warming events on this marginal population of L. digitata. Résumé : Photosynthèse de Laminaria digitata au cours des périodes d'immersion et d'émersion de marées de vive-eau par temps chaud et ensoleillé. La laminaire d'affinité boréale Laminaria digitata domine l'infralittoral desShow less >

Language :

Anglais

Popular science :

Non

Collections :

• Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL