Effect of uv-b radiation on biomass production, pigmentation and protein content of marine diatoms

Abstract

Several species of marine diatoms were grown at + 18 °C and + 22 °C under normal air conditions (0.035 vol.% C 02) at a light/dark alteration o f 14: 8 h. Intensity of white light was 1 mW (~ 5000 lux). An artifical nutrient solution of 35%o salinity was used. Algae - harvested during exponential growth — were exposed to different intensities of UV-B radiation (439, 717 and 1230 J · m-2· m-1) for 2 days. UV-B radiation depressed thegrowth of all tested marine diatoms. Low levels of UV-B resulted in a slight increase of the biomass production (dry weight) compared to not UV-B treated cells. Enhanced UV-B doses caused a dim inution of 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 c1+ c2and carotenoids). In + 22 °C grown cells of Lauderia annulata and Thalassiosira rotula were more sensitive to UV-B radiation than those cultures grown at + 18 °C. Bellerochea yucatanensis cells grown at + 2 2 °C were less affected after UV-B exposure than at + 18 °C grown algae. The UV-B sensibility and growth of the individual species varied in a mixture of several marine diatoms. Results were discussed with reference to the UV-B effect on metabolic processes. © 1984, Walter de Gruyter. All rights reserved.