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Communication at the NABS Annual meeting, Keystone, 2000
(390) DISTRIBUTION OF ULTRAVIOLET LIGHT EFFECTS ON PERIPHYTON IN THE LITTORAL ZONE OF AN OLIGOTROPHIC BOREAL FOREST LAKE.
P. Weidman1, M.A. Turner2, L.G. Goldsborough1, and H. Kling2. 1Department of Botany, University of Manitoba, Winnipeg, MB, Canada R3T 2N2, 2Freshwater Institute, 501 University Cres., Winnipeg, MB, Canada R3T 2N6
Epilithic metabolism, algal and chemical composition, and stoichiometry were examined to determine the distribution of UV effects on littoral periphyton over depth and time from mid-June to mid-August 1999 in Lake 224 at the Experimental Lakes Area, northwestern Ontario. Epilithon colonized on vitrified clay tiles were both exposed to, and shielded from, natural ultraviolet light (UV: 280 to 400nm) using two types of Plexiglas filters, which were submerged at three depths over a range of 0.5 to 1.5 meters. The effectiveness of the UV treatments was confirmed by exposing UV-sensitive polysulfone film. Preliminary analysis indicates that UV stimulated respiration at 0.5 meters during initial colonization. This effect diminished immediately over depth and subsequently over time. With increased depth, relative respiration decreased while relative photosynthesis increased; this effect also diminished over time. Inhibition of photosynthesis was hypothesized to decrease the epilithic C:P ratio by reducing C fixation, and increases in respiration would further decrease C:P by increasing the expiration of C. Species of larger biovolume were expected to dominate initially colonized epilithon.
Presented at 1:00 PM on Wednesday, May 31, 2000 in Periphyton
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