Effect of UV-B Radiation on Biomass Production, Pigmentation and Protein Content of Marine Diatoms

UV-B Stress, Pigment and Protein Content, Pure Cultures o f Marine D iatom s Several species o f marine diatoms were grown at + 18 °C and + 2 2 °C under normal air condi­ tions (0.035 vol.% C 0 2) at a light/dark alteration o f 14: 8 h. Intensity o f white light was 1 mW (~ 5000 lux). An artifical nutrient solution o f 35%o salinity was used. Algae harvested during exponential growth — were exposed to different intensities o f UV-B radiation (439, 717 and 1230 J • m2 • n r 1) for 2 days. UV-B radiation depressed the growth o f all tested marine diatoms. Low levels of UV-B resulted in a slight increase o f the biomass production (dry weight) compared to not UV-B treated cells. Enhanced UV-B doses caused a dim inution o f the primary productivity in all species. Algae exposed to UV-B stress showed a marked decrease in the protein and pigment content (chlorophyll a, chlorophyll c, + c2 and carotenoids). In + 2 2 °C grown cells of Lauderia annulata and Thalassiosira rotula were more sensitive to UV-B radiation than those cultures grown at + 1 8 °C. Bellerochea yucatanensis cells grown at + 2 2 °C were less affected after UV-B exposure than at + 1 8 °C grown algae. The UV-B sensibility and growth o f the individual species varied in a mixture of several marine diatoms. Results were discussed with reference to the UV-B effect on metabolic processes.