EVALUATION OF CHLOROPHYLL FLUORESCENCE, IN-VIVO SPECTROPHOTOMETRIC PIGMENT ABSORPTION AND ION LEAKAGE AS BIOMARKERS OF UV-B EXPOSURE IN MARINE MACROALGAE

The photosynthetic fluorescence ratio F-v:F-m, in vivo absorption spec tra and ion leakage were evaluated as biomarkers of ambient and elevat ed UV-B (280 to 320 nm) exposure of the intertidal alga Enteromorpha i ntestinalis (Chlorophyta) and the sublittoral alga Palmaria palmata (R hodophyta). Measurements of thallus growth were also used to assess ad verse biological effects. Ambient and elevated UV-B significantly inhi bited photosynthesis in both species. It was shown that the F-v:F-m ra tio is a sensitive, non-specific general biomarker of UV-B exposure in both species. Moreover, the in vivo absorption of what was tentativel y identified as chlorophylls a and b as well as phycoerythrin and/or c arotenoids, phycoerythrobilin and phycocyanin decreased in a dose-resp onse dependent manner and was associated with a decrease in growth rat e in P. palmata. The intertidal alga E. intestinalis showed a greater degree of tolerance to UV-B exposure. These results indicate that chan ges in the F-v:(F)m ratio together with reductions in in vivo pigment absorption could provide an early quantitative warning of the detrimen tal effects of UV-B in marine macroalgae.