Phytoplankton photoadaptation to vertical excursion as estimated by an in vivo fluorescence ratio

Abstract

Phytoplankton photoadaptation to vertical excursion as estimated by an in vivo fluorescence ratio* 'Institut Maurice-Lamontagne, Ministere des PQches et des Oceans. BP 1000, Mont-Joli. Quebec, Canada G5H 324 '~e p a r t e m e n t d e biologie. Universitk Laval, QuBbec, QuQbec. Canada G1K 1P4ABSTRACT. To measure the photoadaptation status of phytoplankton. Demers e t al. (1985) used a fluorescence ratio which was dependent on the recent history of light exposure. A field survey of different phytoplankton populations in different oceanographic conditions was carried out to investigate the variations in this fluorescence ratio for natural populations. Results indicated that despite different stratification regimes, the vertical profiles of this fluorescence ratio could be interpreted adequately in terms of mixing and sinking. Using a simple conceptual model, which depends on the different time scales required for adaptation to bright irradiance and darkness, it is shown that this interpretation of the fluorescence ratio 1s consistent with a physical estimation of mixing calculated from wind data. Additional information on photoinhibition and sinking was obtained. This simple model may prove useful as a tool for identifying effects of vertical excursion on phytoplankton photoadaptation directly from vertical profiles of the proposed fluorescence ratio.

Inferred influence of nutrient availability on the relationship between Sun‐induced chlorophyll fluorescence and incident irradiance in the Bering Sea

“…It is possible, if not likely, that in many parts of the ocean, the fluorescence parameters a F abs and f f (1500) as estimated in this study are influenced strongly by physiological parameters other than nutrient status. For example, light history and acclimation of the phytoplankton should have some impact on the fluorescence properties [Therriault et al, 1990;Demmig-Adams et al, 1995;Park et al, 1996;Neale et al, 1998;Laney et al, 2005]. Thus the mixing depth could be of importance when interpreting fluorescence parameters.…”

Rapid light-induced changes in cell fluorescence and in xanthophyll-cycle pigments of Alexandrium excavatum (Dinophyceae) and Thalassiosira pseudonana (Bacillario-phyceae): a photo-protection mechanism

“…It allows algae to accomodate to rapid changes in the light field and permits cells to build u p longer-term mechanisms of photoprotection such as regulation of pigment content and composition. Moreover, in the context of using photoadaptative responses of phytoplankton cells a s a n index of vertical mixing (Lewis et al 1984, Cullen & Lewis 1988, Therriault et al 1990), a n understanding of light-governed rapid changes in cellular fluorescence and reactions of photo-protective pigments could become useful tools in modelling vertical mixing.…”

In situ variations of the xanthophylls diatoxanthin and diadinoxanthin: photoadaptation and relationships with a hydrodynamical system in the eastern English Channel

“…This result agrees with that of Denman & Gargett (1983), who found vertical transfer rates of 10 m for cells by turbulence ranged between some minutes to several hundred hours. The relationship between vertical mixing and photoadaptation has been studied with the aid of physical models (Lewis et al 1984, Cullen & Lewis 1988, Yarnazaki & Kamykowski 1991, Prezelin et al 1991, or with variation of in vivo fluoresence (Therriault et al 1990) but this is the first example of a pigment marker for such a relationship.…”

“…Thus, the measurements of diadinoxanthin and diatoxanthin contents can give an indication of the ecological past of the cells (light conditions, water turbidity) and could become an indicator of the movements of the water masses and of their turbulence (Lewis et al 1984, Cullen & Lewis 1988, Therriault et al 1990, Kerherve 1991.…”