|Studies on the phytoplankton ecology of the Trondheimsfjord. II. Chloroplast pigments in relation to abundance and physiological state of the phytoplankton|
Jensen, A.; Sakshaug, E. (1973). Studies on the phytoplankton ecology of the Trondheimsfjord. II. Chloroplast pigments in relation to abundance and physiological state of the phytoplankton. J. Exp. Mar. Biol. Ecol. 11(2): 137-155
In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981, more
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The quantitative composition of the chloroplast pigments of phytoplankton sampled weekly at 1 station in the Trondheimsfjord was studied by circular paper chromatography throughout 18 months. The concentrations of total chlorophyll a (T-chl a obtained by the trichromatic method) as well as of chromatographically purified chlorophyll a (chl a) followed the variations in phytoplankton concentration. 2 spring blooms and a weak autumn flowering of phytoplankton were clearly reflected in the pigment contents found, namely 14-16 mg T-chl a/m for the spring maxima, corresponding to nearly 300 mg T-chl a/m for the euphotic zone; and 3-4 mg/m3) or 32 mg/m3 for the autumn peak. The concentrations between blooms amounted to ~ 61 mg T-chl a/m2), while concentrations down to 0.03 mg/m3 were found for winter samples. The content of T-chl a was high in diatom cells prior to a bloom (20- 40 x 10-9) mg /cell). During rapid growth (a more or less exponential phase) the cell content of chloroplast pigments decreased (to 5-10 x 10-9mg). No degradation product of chlorophylls coud be detected during this phase and the percentage of chl a (of T-chl a) was high (70-80%). At the peak of the bloom, and especially when the nitrate content in the surrounding water had been exhaused, low values for T-chl a were found (0.3-0.5 x 10-9 mg/cell). As soon as the cell counts started to fall, or even before the decline could be clearly detected, the percentage of chl a dropped (to 40-20%) and derived chlorophylls (not phaeophytin a) were present in the samples. Model studies with cultured algae showed a similar behaviour. It is concluded that the proportion of chl a to T-chl a and the occurrence of chlorophyll derivatives in phytoplankton samples can give valuable information on the stage of development of the algal populations involved.