UV effects on photosynthesis and DNA in propagules of three Antarctic seaweeds (Adenocystis utricularis, Monostroma hariotii and Porphyra endiviifolium).
Ozone depletion is highest during spring and summer in Antarctica, coinciding with the seasonal reproduction of most macroalgae. Propagules are the life-stage of an alga most susceptible to environmental perturbations therefore, reproductive cells of three intertidal macroalgal species Adenocystis utricularis (Bory) Skottsberg, Monostroma hariotii Gain, and Porphyra endiviifolium (A and E Gepp) Chamberlain were exposed to photosynthetically active radiation (PAR), PAR + UV-A and PAR + UV-A + UV-B radiation in the laboratory. During 1, 2, 4, and 8 h of exposure and after 48 h of recovery, photosynthetic efficiency, and DNA damage were determined. Saturation irradiance of freshly released propagules varied between 33 and 83 mumol photons m(-2) s(-1) with lowest values in P. endiviifolium and highest values in M. hariotii. Exposure to 22 mumol photons m(-2) s(-1 )PAR significantly reduced photosynthetic efficiency in P. endiviifolium and M. hariotii, but not in A. utricularis. UV radiation (UVR) further decreased the photosynthetic efficiency in all species but all propagules recovered completely after 48 h. DNA damage was minimal or not existing. Repeated exposure of A. utricularis spores to 4 h of UVR daily did not show any acclimation of photosynthesis to UVR but fully recovered after 20 h. UVR effects on photosynthesis are shown to be species-specific. Among the tested species, A. utricularis propagules were the most light adapted. Propagules obviously possess good repair and protective mechanisms. Our study indicates that the applied UV dose has no long-lasting negative effects on the propagules, a precondition for the ecological success of macroalgal species in the intertidal.
Zacher
Katharina
K
Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany. kzacher@awi-bremerhaven.de
Roleda
Michael Y
MY
Hanelt
Dieter
D
Wiencke
Christian
C
D000864:Antarctic Regions; D004249:DNA Damage; D018744:DNA, Plant / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects*; D012624:Seaweed / Q000502:physiology / Q000528:radiation effects*; D013170:Spores / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays
D018744:DNA, Plant