Electron requirements for carbon incorporation along a diel light cycle in three marine diatom species
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Diatoms account for about 40% of primary production in highly productive ecosystems. The development of a new generation of fluorometers has made it possible to improve estimation of the electron transport rate from photosystem II, which, when coupled with the carbon incorporation rate enables estimation of the electrons required for carbon fixation. The aim of this study was to investigate the daily dynamics of these electron requirements as a function of the diel light cycle in three relevant diatom species and to apprehend if the method of estimating the electron transport rate can lead to different pictures of the dynamics. The results confirmed the species-dependent capacity for photoacclimation under increasing light levels. Despite daily variations in the photosynthetic parameters, the results of this study underline the low daily variability of the electron requirements estimated using functional absorption of the photosystem II compared to an estimation based on a specific absorption cross section of chlorophyll a. The stability of the electron requirements throughout the day would suggest it is potentially possible to estimate high-frequency primary production by using autonomous variable fluorescence measurements from ships-of-opportunity or moorings, without taking potential daily variation in this parameter into consideration, but this result has to be confirmed on natural phytoplankton assemblages. The results obtained in this study confirm the low electron requirements of diatoms to perform photosynthesis, and suggest a potential additional source of energy for carbon fixation, as recently described in the literature for this class.
KeywordsPhytoplankton Photosynthesis PAM 13C incorporation Electron transport rate (ETR)
We thank Juliette Fauchot and Bertrand Le Roy for providing the diatom strains and Anne-Flore Deton for technical assistance. We are also really grateful to Camille Napoleon for technical help and constructive exchanges during this study. This work was support by the GIP Seine-Aval project “PROUESSE” and the SMILE 2 project supported by l’Agence de l’Eau Seine Normandie.
- Falkowski PG (1984) Physiological responses of phytoplankton to natural light regimes. 6(2):295–307Google Scholar
- Gilbert M, Wilhelm C, Richter M (2000) Bio-optical modelling of oxygen evolution using in vivo fluorescence: comparison of measured and calculated photosynthesis/irradiance (P-I) curves in four representative phytoplankton species. J Plant Physiol 157(3):307–314. Available from: http://linkinghub.elsevier.com/retrieve/pii/S0176161700800528
- Hancke K, Hancke TB, Olsen LM, Johnsen G, Glud RN (2008b) Temperature effects on microalgal photosynthesis-light responses measured by O2 production, pulse-amplitued-modelated fluorescence and 14C assimilation. 514:501–514Google Scholar
- Houliez E, Simis S, Nenonen S, Ylöstalo P, Seppälä J (2017) Basin-scale spatio-temporal variability and control of phytoplankton photosynthesis in the Baltic Sea: the first multiwavelength fast repetition rate fluorescence study operated on a ship-of-opportunity. J Mar Syst 169:40–51CrossRefGoogle Scholar
- Huisman J, Sharples J, Stroom JM, Visser PM, Kardinaal WEA, Verspagen J et al. (2004) Changes in turbulent mixing shift competition for light between phytoplakton species. 85(11):2960–2970Google Scholar
- Jouenne F, Lefebvre S, Véron B, Lagadeuc Y (2005) Biological and physicochemical factors controlling short-term variability in phytoplankton primary production and photosynthetic parameters in a macrotidal ecosystem (eastern English Channel). Estuar Coast Shelf Sci 65(3):421–439CrossRefGoogle Scholar
- Lavaud J (2007) Fast regulation of photosynthesis in diatoms: mechanisms, evolution and ecophysiology [Internet]. Vol. 1, Funct Plant Sci Biotechonol. Available from: https://hal.archives-ouvertes.fr/hal-01094678/
- Oxborough K, Moore CM, Suggett DJ, Lawson T, Chan HG, Geider RJ (2012) Direct estimation of functional PSII reaction center concentration and PSII electron flux on a volume basis: a new approach to the analysis of Fast Repetition Rate fluorometry (FRRf) data. Limnol Oceanogr 10:142–154CrossRefGoogle Scholar
- Pauly D, Christensen V (1995) Primary production required to sustain global fisheries. 374(March):255–257Google Scholar