Marie‐Andrée Janquin

Laboratoire d’Océanologie et de Géosciences

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Dominique Davoult

Station Biologique de Roscoff

François Gévaert

Université de Lille

Dominique Menu

Institut français d'études sur l'Asie centrale

Aline Migné

Adaptation et Diversité en Milieu Marin

Gaspard Delebecq

Institut Universitaire Européen de la Mer

Nicolas Spilmont

Laboratoire d’Océanologie et de Géosciences

Lionel Denis

Laboratoire d’Océanologie et de Géosciences

Cédric Hubas

Biologie des Organismes et Écosystèmes Aquatiques

Mathieu Rauch

Centre National de la Recherche Scientifique

Guy Boucher

Biologie des Organismes et Écosystèmes Aquatiques

Cooperative Institutions

Centre National de la Recherche Scientifique

Université de Lille

Université Lille Nord de France

Laboratoire d’Océanologie et de Géosciences

Sorbonne Université

Institut de Recherche pour le Développement

Station Biologique de Roscoff

Université du littoral côte d'opale

Adaptation et Diversité en Milieu Marin

Biologie des Organismes et Écosystèmes Aquatiques

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Carbon and nitrogen content of Laminaria saccharina in the eastern English Channel: biometrics and seasonal variations

Journal of the Marine Biological Association of the United Kingdom (2001)

François Gévaert Dominique Davoult Anne Créach Robert Kling Marie‐Andrée Janquin

Fresh weight (FW), dry weight (DW), carbon and nitrogen content were measured for specimens of Laminaria saccharina (Heterokontophyta: Phaeophyceae) sampled in the eastern English Channel in order to conduct a biometrical study. The aim was to relate carbon and nitrogen masses of the algae to a simple and rapid morphological measurement of the total length of the sporophyte. These relationships were highly significant and appeared very useful to express the standing biomass of L. saccharina in terms of carbon or nitrogen and then to consider dynamic processes such as primary production. Variations in tissue carbon (C) and nitrogen (N) were examined over a complete seasonal cycle. Average carbon and nitrogen content ranged from 23·9 to 31·4% and 2·23 to 3·42% of the total dry weight, respectively. Variations in C/N ratio showed a clear seasonal pattern with an increase in the early spring corresponding to strong photosynthesis and growth.

Saccharina

Dry weight

Sporophyte

Carbon fibers

10.1017/s0025315401004532

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Citations (66)

Gas‐phase reaction of hydroxyl radicals with m‐, o‐ and p‐cresol

International Journal of Chemical Kinetics (2006)

Cécile Coeur-Tourneur Françoise Henry Marie‐Andrée Janquin Laurent Brutier

Abstract The gas‐phase reaction of oxygenated aromatic compounds m ‐cresol, o ‐cresol, and p ‐cresol with hydroxyl radicals has been studied by GC‐MS. Experiments have been performed in a large‐volume photoreactor (8000 L) at 294 ± 2 K and atmospheric pressure. The relative kinetic method was used to determine the rate constants for these reactions, with 1,3,5‐trimethylbenzene as a reference compound. The rate constants obtained are k OH ( m ‐cresol) = (5.88 ± 0.92) × 10 −11 cm 3 molecule −1 s −1 , k OH ( o ‐cresol) = (4.32 ± 0.52) × 10 −11 cm 3 molecule −1 s −1 , and k OH ( p ‐cresol) = (4.96 ± 0.75) × 10 −11 cm 3 molecule −1 s −1 . The degradation products observed and their respective molar yields were methyl‐1,4‐benzoquinone 12.4 ± 1.2%, 5‐methyl‐2‐nitrophenol 1.5 ± 0.3%, and 3‐methyl‐2‐nitrophenol 1.4 ± 0.3% from m ‐cresol, methyl‐1,4‐benzoquinone 5.6 ± 0.9%, and 6‐methyl‐2‐nitrophenol 4.7 ± 0.8% from o ‐cresol, and 4‐methyl‐2‐nitrophenol 17.2 ± 2.5% from p ‐cresol. This kinetic and product data are compared with the literature, and the reaction mechanisms are discussed. Our results are in accordance with the previous studies (Atkinson, J Phys Chem Ref Data 1989, Monograph (1), 1–246; Atkinson and Aschmann, Int J Chem Kinet 1990, 22, 59–67; Atkinson et al., Environ Sci Technol 1992, 26, 1397–1403; Atkinson et al., J Phys Chem 1978, 82, 2759–2805; Olariu et al., Atmos Environ 2002, 36, 3685–3697; Semadeni et al., Int J Chem Kinet 1995, 27, 287–304) and confirm the methyl‐1,4‐benzoquinone yields determined by a different experimental technique (long‐path Fourier transform infrared FT‐IR (Olariu et al., 2002)). © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 553–562, 2006

p-Cresol

Cresol

10.1002/kin.20186

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Citations (61)

Biometrics in Laminaria digitata: A useful tool to assess biomass, carbon and nitrogen contents

Journal of Sea Research (2008)

François Gévaert Marie‐Andrée Janquin Dominique Davoult

Laminaria digitata

Thallus

Dry weight

Sporophyte

Rocky shore

10.1016/j.seares.2008.06.006

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Citations (36)

In situ photosynthetic performance of Laminaria digitata (Phaeophyceae) during spring tides in Northern Brittany

Gaspard Delebecq Dominique Davoult Dominique Menu Marie‐Andrée Janquin Aline Migné

The ability of Laminaria digitata (Hudson) J.V. Lamouroux to cope with rapid and drastic changes in light was studied in the field by measuring photosystem II fluorescence, net oxygen roduction and pigment content. Experiments were conducted during two spring tides of late spring in Northern Brittany where low spring tides occur around noon. Daily patterns of the photosynthetic performance of Laminaria digitata were observed in relation to changes in incident under- water light. Photoinhibitory light exposure induced a sharp decrease of the optimal quantum yield (Fv/Fm), a decline of the net oxygen production in the first of the two spring tides investigated and a concomitant increase in the de-epoxidation ratio of the Violaxanthin pool. Photoinhibition persisted at a lower extent at the end of the day and complete recovery was achieved during the night. The implications of the photoinhibition of photosynthesis of Laminaria digitata are discussed in relation to the natural ambient conditions experienced in the field.

Laminaria digitata

Photoinhibition

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

HAL (Le Centre pour la Communication Scientifique Directe) (2019)

Aline Migné Gaspard Delebecq Dominique Davoult Nicolas Spilmont Dominique Menu

The boreal kelp Laminaria digitata dominates the low intertidal and upper subtidal zones of moderately exposed rocky shores in north-western 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 (ΦPSII) and optimal (Fv/Fm) 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 gDW-1 h-1) during morning immersion to negative values uduring emersion (reaching -37 μmol C gDW-1 h-1), and did not return to positive values during the following immersion period when respiration was exacerbated. ΦPSII decreased during emersion (down to 0.01), but recovered during afternoon immersion. Fv/Fm 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.

Laminaria digitata

10.5281/zenodo.2574922

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Influence of local environmental conditions on the seasonal acclimation process and the daily integrated production rates of Laminaria digitata (Phaeophyta) in the English Channel

Marine Biology (2012)

Gaspard Delebecq Dominique Davoult Dominique Menu Marie‐Andrée Janquin Jean–Claude Dauvin

Laminaria digitata

Sporophyte

Photoinhibition

Photosynthetic pigment

Light intensity

10.1007/s00227-012-2106-3

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Citations (28)

Annual budget of benthic production in Mont Saint-Michel Bay considering cloudiness, microphytobenthos migration, and variability of respiration rates with tidal conditions

Continental Shelf Research (2009)

A. Migné Nicolas Spilmont Guy Boucher Lionel Denis Cédric Hubas

Respiration rate

10.1016/j.csr.2009.09.004

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Citations (39)

In situ assessment of the daily primary production of the temperate symbiotic coral Cladocora caespitosa

Limnology and Oceanography (2013)

Christine Ferrier‐Pagès François Gévaert Stéphanie Reynaud Éric Béraud Dominique Menu

We assessed the in situ daily primary production, photosynthetic efficiency, and xanthophyll cycling of a temperate coral, Cladocora caespitosa , during the summer using an in situ incubation chamber equipped with temperature, oxygen, light, salinity, and pH sensors. During sunny days, photosynthetic carbon (C) production rates of C. caespitosa can be as high as those measured for tropical corals and rapidly follow changes in natural irradiance (from 200 to 1000 µmol photons m −2 s −1 within 2 h). As a consequence, daily production rates varied by a factor of 2 (from 150 and 260 µg C cm −2 d −1 ) depending on the irradiance received. Under high irradiance levels, corals can suffer from photoinhibition (light‐induced reduction in the photosynthetic capacity), especially temperate species, which do not experience high irradiance levels most of the year. However, in C. caespitosa , photoinhibition at irradiances higher than 1000 µmol photons m −2 s −1 was reduced as a result of the involvement of the xanthophyll cycle, with a degree comparable to those measured for tropical species (de‐epoxidation ratio of 0.12), that allowed C. caespitosa to maintain high production rates and a maximal autotrophic carbon acquisition during sunny days. However, as soon as irradiance conditions decreased below 200 µmol photons m −2 s −1 because of cloudy weather, autotrophically acquired carbon could not sustain respiratory needs, indicating that C. caespitosa has to rely on other sources, such as heterotrophy, to meet its energetic needs.

Photoinhibition

Autotroph

10.4319/lo.2013.58.4.1409

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Citations (9)

Calculation of annual budget of net benthic production in the Mont Saint-Michel Bay with emphasis on the influence of cloudiness, migration of microphytobenthos and variation of the respiration rate with the alternation of emersion-immersion periods

HAL (Le Centre pour la Communication Scientifique Directe) (2009)

Aline Migné Nicolas Spilmont Guy Boucher Lionel Denis Cédric Hubas

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