Received 23 June 1994. Accepted 9 December 1994.
GROWTH OF ANTARCTIC CYANOBACTERIA UNDER ULTRAVIOLET RADIATION: UVA COUNTERACTS UVB INHIBITION1
Article first published online: 28 JUN 2008
Journal of Phycology
Volume 31, Issue 2, pages 242–248, April 1995
How to Cite
Quesada, A., Mouget, J.-L. and Vincent, W. F. (1995), GROWTH OF ANTARCTIC CYANOBACTERIA UNDER ULTRAVIOLET RADIATION: UVA COUNTERACTS UVB INHIBITION. Journal of Phycology, 31: 242–248. doi: 10.1111/j.0022-3646.1995.00242.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- Antarctic cyanobacteria;
- microbial mats;
- Phormidium mur-rayi;
A mat-forming cyanobacterium (Phormidium mur-rayi West and West) isolated from an ice-shelf pond in Antarctica was grown under white light combined with a range of UVA and UVB irradiances. The 4-day growth rate decreased under increasing ultraviolet (UV) radiation, with a ninefold greater response to UVB relative to UVA. In vivo absorbance spectra showed that UVA and to a greater extent UVB caused a decrease in phycocyanin/ chlorophyll a and an increase in carotenoids/chlorophyll a. The phycocyanin/chlorophyll a ratio was closely and positively correlated to the UVB-inhibited growth rate. Under fixed spectral gradients of UV radiation, the growth inhibition effect was dominated by UVB. However, at specific UVB irradiances the inhibition of growth depended on the ratio of UVB to UVA, and growth rates increased linearly with increasing UVA. These results are consistent with the view that UVB inhibition represents the balance between damage and repair processes that are each controlled by separate wavebands. They also underscore the need to consider UV spectral balance in laboratory and field assays of UVB toxicity.