A comparison of photosynthesis measurements by O2 evolution, 14C assimilation, and variable chlorophyll fluorescence during light acclimatization of the diatom Coscinodiscus granii

doi:2015.30.2.103

Algae > Volume 30(2); 2015 > Article

Algae 2015;30(2): 103-119. doi: https://doi.org/10.4490/algae.2015.30.2.103

Erik Trampe¹^,*, Per Juel Hansen¹ and Michael Kühl¹^,2

¹Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
²Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney NSW 2007, Australia

*Corresponding Author

Email: etrampe@bio.ku.dk

ABSTRACT

Photosynthetic rates of the large centric diatom Coscinodiscus granii were measured by means of multicolor variable chlorophyll fluorescence imaging, single cell 14C assimilation, and optical O2 sensor measurements during light acclimatization of cultures grown at five different irradiances: 50, 150, 235, 332, and 450 μmol photons m-2 s-1. Photo-acclimatization was evident from changes of cellular chlorophyll a content, growth rates, and light response curves. Each of the applied methods evaluates different parts and reactions in the photosynthetic apparatus, which makes a direct quantitative comparison of rates difficult, although a different degree of correlation were found between all three methods. However, when used in combination, they provide information about the internal relationship of photosynthetic pathways as well as the variation in photosynthetic capacity between individual cells within a single algal culture.

Key words: 14C incorporation; diatoms; O2 evolution; photo-acclimatization; photosynthesis; variable Chl a fluorescence imaging