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Pigment composition of Heterocapsa sp. and Thalassiosira weissflogii growing in batch cultures under different irradiances
Mikel Latasa

An increase in the ratio of carotenoids/chlorophylls has been widely used as an indicator of light or nutrient stress in phytoplankton. An experiment was carried out to examine the changes of pigment composition in a dinoflagellate, Heterocapsa sp., and a diatom, Thalassiosira weissflogii grown in batch cultures under high (15 0 mmol m-2 s-1) and low (50 mmol m-2 s-1) irradiances. During the exponential growth phase, the cell content of the pigments involved in light harvesting functions such as fucoxanthin, peridinin, chlorophyll c, and chlorophyll a, was higher in cells cultured under lower irradiances. Diadinoxanthin concentration, however, was higher in cells cultured under higher irradiances, which supports a photoprotective role for this pigment. The shift from the exponential to the stationary phase (likely to be a result of nutrient starvation) produced a more drastic pigment loss in cells growing in the high irradiance cultures. As an exception, diatoxanthin showed an important increase, independent of irradiance and especially in T. weissflogii, when cells progressed from the exponential to the stationary phase. This result suggests that this pigment could be used as an indicator of nutrient starvation. In general, pigment ratios were more affected by the nutrient condition of the cells than by the different irradiances.

Keywords: Diatom, dinoflagellate, light intensity, xanthophylls, diatoxanthin, HPLC.
Contents of this volume Sci. Mar. 59(1) : 25-37 Back PDF
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