| Autor: |
Jiři Kopecky, Assaf Sukenik, Jacco C. Kromkamp, Amir Yamshon, Shai Gabai, John Beardall, Stef Van Bergeijk, Jiří Masojídek, Efrat Shaham |
| Přispěvatelé: |
Marine Microbiology |
| Jazyk: |
angličtina |
| Rok vydání: |
2009 |
| Předmět: |
|
| Zdroj: |
Aquatic Microbial Ecology, 56(2-3), 309-322. Inter-Research |
| ISSN: |
0948-3055 |
| Popis: |
The present study evaluated productivity under different operational (optical) condi- tions using the unicellular alga Nannochloropsis sp. (Eustigmatophyta). This alga is often grown in mass algal cultures because it contains high contents of the polyunsaturated fatty acid, eicosapen- taenoic acid (EPA, 20:5ω3). We followed biomass, photosynthetic activities and physiological parame- ters in a 3 d experiment using various photosynthesis techniques in 2 outdoor cultivation systems: a flat panel photobioreactor (FPP) and a high rate algal pond (HRAP). We aimed to detect acclimation behaviour to the different optical conditions, with the FPP having a short light path and the HRAP having a long light path. Both algae cultures showed an afternoon depression of photosynthetic activ- ity, which was more pronounced in the FPP. Therefore, the HRAP culture showed 'classical' shade adaptation behaviour, whereas the FPP algae was high-light acclimated. The FPP showed diurnal changes in the potential rates of photosynthesis and respiration. High temperatures (41°C) on Day 3 in the FPP caused a large reduction in the maximum Photosystem II (PSII) efficiency (Fv/Fm) and an over-reduction of the PSII acceptors, which did not recover during the light period. Chlorophyll fluo- rescence measurements with and without dark adaptation suggested that the decreased photosyn- thetic activity was due to both chronic and dynamic downregulation. Photodamage was higher in the FPP, but most was recovered during the evening. A comparison between the quantum efficiencies for PSII charge separation and oxygen evolution revealed a close coupling between the 2 processes. We also concluded that the optical absorption cross section of PSII equalled 75% of the total absorption cross section. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
