Aquatic Sciences Meeting, Albuquerque 2001

PC17 Phytoplankton Physiology and Ecology

Date: Thursday, February 15, 2001

Location: Southwest Hall

Le Floc'h, E, , LOBEPM, ESA 7076, Villefranche sur Mer, France, lefloch@obs-vlfr.fr

Sciandra, A, , LOBEPM, ESA 7076, Villefranche sur Mer, France, sciandra@obs-vlfr.fr

ADAPTATION OF PIGMENT COMPOSITION TO INTERACTIVE EFFECTS OF LIGHT AND NITROGEN IN RHODOMONAS SALINA (CRYPTOPHYCEAE)

Numerous laboratory experiments have studied how photon flux or nitrogen availability influence pigment composition and photosynthetic activity of various autotrophic species. However, the consequences of their interactive effects have been less thoroughly examined although photon flux and nitrogen concentration can be simultaneously at sub-optimal levels in the natural environment. Our results show that the Cryptophyceae Rhodomonas salina grown in chemostats with multiple combinations of light intensity and nitrate exhibit an important diversity of pigment and photosynthetic adaptations. Especially, the amplitudes of the shifts in pools of chlorophyll a and phycoerythrin vary with the degree of the limitation of photon flux and of nitrogen availability. Futhermore, different combinations of irradiance and nitrate limitation can induce identical pigment composition. This suggests that the capacity of the cells for photosynthesic adaptation when submitted to limitation by one factor (light or nitrogen) depends on the level of the other variable. These results highlight the need for models of photosynthesis to take into account the interactive effects of environmental factors.

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

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