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ISSN: 1940-4328 Online

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Year 2004, Volume 6 / Issue 4

DOI: 10.1615/InterJAlgae.v6.i4

Pages: 102

DOI: 10.1615/InterJAlgae.v6.i4.40

Article price - $35.00

The photosynthetic apparatus of the Barents Sea Fucales (Phaeophyta) after polar night

I. V. Tropin
M.V. Lomonosov Moscow State University, Biological Department, 119899 Moscow, MSU (Building 1, Suite 12), Russia

M. V. Makarov
Murmansk Marine Biology Institute, Kola Scientific Center of Russian Academy of Sciences,

During 43 days of natural and laboratory experiments, it was demonstrated that changes in pigment concentrations occur during polar night in Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea. An insignificant increase in the amount chlorophyll and fucoxanthin was noted in the species inhabiting the upper intertidal zone. In the lower littoral species, a prolonged stay in the darkness caused a decrease in pigment contents. Species-specific changes in pigment contents evidently depended on the depth of the algae habitats in the littoral zone and quite probably were conditioned by the anatomical and morphological differences in the thallus structure (the ratio between the assimilation and heterotrophic cell layers). The ability of Fucales to maintain the pigment contents in the cells had increased before the beginning of the polar night and was determined by their continuing metabolic activity. A metabolism type similar to that noted in the littoral Fucales is usually typical of optional heterotrophs. During the subsequent 7 days of the regeneration period (illuminance ca. 6−10 mcM/m²s), the decrease in photosynthetic pigment concentrations was registered in the investigated algae that quite probably was a trait of adaptation to some increase in the illuminance level. All Fucales contained in the darkness and stayed in the natural conditions on the littoral possessed a well-expressed photosynthetic activity. The lowering of functional activity of the photosynthetic apparatus, established at the end of the polar night, was reversible. Visible photosynthesis in the algae from the natural habitats exceeded 4−10 times the amount found in algae contained in the darkness. Photosynthetic activity decreased in the following series: F. serratus ≥ A. nodosum ≥ F. vesiculosus. The ability of the algae contained in the darkness to restore their photosynthetic activity depended to a greater extent on the illuminance level. At the 24-hour illumination at approximately 17 mcM/m²s the restored photosynthesis quickly reached the level of test specimens. The increase in photosynthetic activity of the algae from natural habitats did not occur at the same illumination level.

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