Effects of solar and artificial radiation on motility and pigmentation in Cyanophora paradoxa

The effects of solar radiation and artificial UV irradiation on motility and pigmentation were studied in the flagellate system Cyanophora paradoxa. Both percentage of motile cells and average velocity decreased drastically after a solar exposure of a few hours. This effect was not due to an overheating since the cells were exposed under temperaturecontrolled conditions. Partial reduction of the UV-B radiation by cut-off filters or by insertion of an artificial ozone layer increased the tolerated exposure times. Artificial UV radiation also induced the same effects. Under both solar and artificial UV irradiation the photosynthetic pigments within the cyanelles were bleached also within short exposure times. Kinetics of pigment destruction showed that the accessory phycobilins are lost with a half life of 1.3 h while the chlorophylls had a half life of 33 h and a carotenoid with an absorption maximum at 480 nm of 17.3 h.