Evaluation of in vivo thallus absorptance and chlorophyll fluorescence as biomarkers of UV-B exposure and effects in marine macroalgae from different tidal levels

• Published in: Marine environmental research 1999-09, Vol.48 (3), p.193-212
• Main Authors: Cordi, B, Hyde, P, Donkin, M.E, Price, D.N, Depledge, M.H
• Format: Article
• Language: English
• Subjects: Algae; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomarker; Chlorophyll fluorescence; Coastal waters; Fundamental and applied biological sciences. Psychology; In vivo spectrophotometric absorptance; Marine; Ozone depletion; Palmaria palmata; Porphyra umbilicalis; Sea water ecosystems; Synecology; UV-B
• ISSN: 0141-1136; 1879-0291
• DOI: 10.1016/S0141-1136(99)00041-0

A field survey and an outdoor experiment were conducted to evaluate the potential of chlorophyll fluorescence and in vivo absorptance spectra as biomarkers of short-term experimental and long-term solar UV radiation exposure in macroalgae. The eulittoral macroalga Porphyra umbilicalis (L.) (Rhodophyta) and the sublittoral macroalga Palmaria palmata (L.) (Rhodophyta) were collected at three different sites along a vertical transect on the beach and in the water column. Significant decreases in the absorptance spectra at 497 and 569 nm (consistent with the presence of R-phycoerythrin and/or carotenoids and phycoerythrobilin, respectively) occurred in P. palmata after exposure to elevated UV-B (2.7 Wm −2). Furthermore, depth-dependent decreases in thallus absorptance at specific wavelengths were found after all exposures, indicating that in vivo thallus absorptance may be a useful general indicator of UV exposure in conjunction with other biomarkers. Also, a depth-dependent decrease in F v F m was detected in P. palmata. A 60% decrease in thallus absorptance and lack of recovery in chlorophyll fluorescence F v F m ratio indicated irreversible damage to accessory pigments, chlorophyll a and photosystem II after exposure to elevated UV-B. Moreover, a depth-dependent increase in thallus absorptance between 290 and 325 nm was observed in P. palmata in response to short-term experimental elevated UV-B exposure and between 290 and 380 nm in response to long-term solar UV-B. In contrast, the eulittoral alga Porphyra umbilicalis exhibited a greater degree of tolerance of UV-B exposure. The results highlight the potentially damaging effects of high irradiances of photosynthetically active radiation and UV and the necessity of utilising several biomarkers when assessing the biological effects of UV-B irradiation associated with ozone depletion.