Bacterioplankton viability in Antarctic waters as affected by solar ultraviolet radiation

Abstract

The effect of solar ultraviolet radiation (UVR) on viability of natural bacterioplankton assemblages as well as on two cultures of isolated bacterial strains (Acinetobacter sp. and Bacillus sp) was determined by both in situ and temperature-controlled incubator experiments. The magnitude of UVR-induced inhibition in natural assemblages, decreased with depth so that there was no significant inhibition at 9.5 m. There was very little effect of photosynthetically available radiation (PAR), even at 0.5 m depth. The loss of viability due to UVR or PAR was much greater for the two isolated strains than for the natural bacterial assemblages. The SOS-repair system could be induced in both bacterial strains studies with the result that the loss in viability due to UVR radiation was much reduced, but both strains still showed some loss of viability when compared to the control samples. -from Authors