| 1. |
- Richardson, Katherine, et al.
(author)
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The relationship between photosynthesis measured by C-14 incorporation and by uptake of inorganic carbon in unicellular algae
- 1984
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In: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 81:3, s. 241-250
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Journal article (peer-reviewed)abstract
- The traditional 14C method of estimating photosynthetic rates was compared with net photo-synthesis in two species of unicellular algae. Net photosynthesis was defined as the disappearance of inorganic carbon from the algal medium and was determined using a described infra-red gas analyser (IRGA) technique. For Amphidinium carterae Hulbert, the 14C method always led to lower calculated rates of photosynthesis than the IRGA technique. This difference was, on average, ≈100%. For Scenedesmusobliquus (Turpin) Kützing, the 14C method could lead to over-estimates, good agreement with, or underestimates of net photosynthesis. Although the under-estimates were only of the order of 15%, the over-estimates were in some cases > 100%. There is some indication that respiration rate is an important factor in the relationship between photosynthetic rates calculated by the two methods for this organism.
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| 2. |
- Sakshaug, E, et al.
(author)
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Chemical composition and alkaline phosphatase activity of nutrient-saturated and P-deficient cells of four marine dinoflagellates
- 1984
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In: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 77, s. 241-254
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Journal article (peer-reviewed)abstract
- Four marine dinoflagellates, Amphidinium carterae Hulburt, Ceratium tripos (O.F. Müll.) Nitzsch, Prorocentrum minimum (Pav.) J. Schiller, and Scrippsiella trochoidea (Stein) Loeblich III were grown as dilution cultures at 18°C, S = 29%. and 30 μE·m−2·s−1 at L:D = 14:10 h. In nutrient-saturated cultures, the growth rates (doubl·day−1) ranged from 0.38 for Scrippsiella to 0.80 for Prorocentrum, and carbon content (pg·cell−1) from 83 for Amphidinium to 6900 for Ceratium. The atomic N/C ratio was 0.13–0.15, but for Ceratium it was 0.088, because of its thick, cellulose theca. The atomic N/P ratio ranged from 12–13 for Ceratium and Scrippsiella to 15–17 for Prorocentrum and Amphidinium. Under P-deficient conditions (growth rate 39–70% of the maximum), cellular P decreased considerably, but so did N, so that the N/P ratio was only slightly affected. There was a concomitant increase in carbon content per cell of 1.2- to 1.7-fold. Alkaline phosphatase activity was virtually nil in nutrient-saturated cells, but was readily demonstrable in all species when P-deficient.
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