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[A-5.1.3 Acclimation of Marine Algae to the Enhanced UV-B(Final Report)]

[Contact Person]

Masayuki Yamamoto
Chief Scientist, Demonstration Laboratory
Marine Ecology Research Institute
4-7-17 Arahama, Kashiwaziki, Niigata 945- 03, Japan
Tel: +81-257-24-8300 Fax: +81-257-24-5576

[Total Budget for FY1993-FY1995]

13,241,000 Yen (FY1995;3,724,000 Yen)

[Abstract]

　The research is aimed to examine the UV- tolerance of seaweeds and the change of the tolerance in UV- irradiated seaweed bodies. Experimental cultivations of red algae were carried out with UV- irradiance only during light period in 12L:12D photoperiod. The experiments of Chrysymenia wrightii showed short term effects, which included the decrease of photosynthetic pigments and UV- absorbing components during the first light period, and the long term effects, which included the decrease of photosynthetic pigments, the increase of UV- absorbing components, and the lowered growth rate through the second light period. In same experiments of Porphyra pseudolinearis, however, the growth rate, which was lowered at once immediately after the first light period started, was recovered through the third or fourth light period when UV- absorbing components increased. Surveys of UV- absorbing components distribution in wild plants of C. wrightii showed that the apical portion contains the components with higher concentration than the basal portion. Experimental cultivation, with UV- irradiated seawater as culture medium, indicated that increase of nitrous acid concentration and other undetected changes in UV- irradiated seawater lowered growth rates of C. wrightii and P. pseudolinearis.

[Key Words]

Seaweed, UV-B, Growth, Photosynthetic pigment, UV-absorbing component