IMPACT OF UV-RADIATION OF DIFFERENT WAVEBANDS ON THE PIGMENTATION OF THE HAPTOPHYCEAN PAVLOVA

The temperate marine phytoplankton species Pavlova lutheri (Droop) Gre en, Pavlova spec. and Thalassiosira rotula (Meunier) were grown at 18 degrees C, with normal air (0.035 vol.% CO2) and a light-dark rhythm o f 12-12 h (2 W m(-2)), in an artificial seawater medium (35 parts per thousand salinity). The Pavlova species were irradiated with UV light of different wavebands (Philips lamps TL 20 W/12; cut-off filters WG 2 95, 305 and 320) in conjunction with white light (4 W m(-2)), The pigm ent patterns were estimated by high performance liquid chromatography for the different phytoplankton species. Chlorophyll a, fucoxanthin an d diadinoxanthin are the dominant pigments. Chlorophyll c, cis and neo fucoxanthin and beta-carotene and diatoxanthin are the other pigments. Chlorophyllid alpha was also found in Thalassiosira. The impact of UV radiation on the pigmentation was studied with Pavlova only. The dama ging effects on the pigments are dependent on the UV wavebands and the exposure time. Short waveband UV radiation (WG 295) causes a marked d epression of all pigment synthesis, whereas UVA irradiation (WG 320) h as practically no effect or leads to an enhancement of neofucoxanthin and chlorophyll c. After 5-8 h UV exposure, a more pronounced damaging effect on the pigments of Pavlova spec. in comparison with Pavlova lu theri is found. The contents of chlorophyll a, beta-carotene and diato xanthin of both tested species are significantly reduced by UV irradia tion. Pigmentation is less affected by UVA (WG 320) than by UVB (WG 29 5, WG 305). The UV-induced increase in neofucoxanthin can probably be explained by a stimulation of the biosynthesis and degradation of fuco xanthin.