Cytological damage to the red alga Griffithsia pacifica from ultraviolet radiation

Continuous exposure for 7-10 days to 60% of ambient levels (sea level at mid-day in December) of UV-A and UV-B radiation caused cytological damage to regenerating fragments of Griffithsia pacifica under laboratory conditions. There was high mortality of individual cells and entire fragments in UV treated filaments. Rhizoid initiation was slower and rhizoids grew more slowly following UV treatment. After 7 days, UV radiated thalli showed chloroplast and nuclear degeneration. In addition, filaments tended to disarticulate so that single or groups of apparently healthy cells were common in the medium. These data suggest that the subtidal habitat of G. pacifica is based in part on lack of tolerance to UV radiation, and that UV protection mechanisms are not inducible or insufficient to prevent the accumulation of damage in this species.