Measurement of photosynthesis and photosynthetic efficiency in two diatoms

• Published in: New Zealand journal of botany 2014-01, Vol.52 (1), p.6-27
• Main Authors: Torres, MA, Ritchie, RJ, Lilley, RMcC, Grillet, C, Larkum, AWD
• Format: Article
• Language: English
• Subjects: Algae; Amphora; Amphora coffeaeformis; Bacillariophyceae; Chlorophyll; chlorophyll fluorescence; diatom; Efficiency; electron transfer; Environmental Sciences; Light; maximum quantum yield; oxygen; P versus E curves; Phaeodactylum tricornutum; photoadaptation; photoinhibition; Photosynthesis; photosynthetic efficiency; photosystem II; rapid light curves; sand; surface area
• ISSN: 1175-8643; 0028-825X; 1175-8643
• DOI: 10.1080/0028825X.2013.831917

Growth, photosynthesis and photosynthetic efficiency have been measured in two diatoms: the commonly studied Phaeodactylum tricornutum and the sand diatom Amphora coffeaeformis . Both diatoms were grown under very high light and under low light (40 µmol.m ⁻².s ⁻¹). Photosynthesis was measured as oxygen yield and as electron transport rate. The ratios of photons absorbed by photosystem II to O ₂ evolved (quantum number), based on chlorophyll a (Θ*) and on surface area (Θ) for P. tricornutum and A. coffeaeformis under low light were between 5 and 6 and 9 and 11, respectively, and under high light were between 16 and 18 and 14 and 17, respectively. P vs E and ETR vs E curves were measured and from the oxygen yield results only a small amount of photoinhibition was observed. In A. coffeaeformis strong non-photochemical quenching was observed. The results show that diatoms exhibit flexible photosynthetic systems and under optimal conditions are very efficient.