SYMPOSIA PAPER Published: 01 January 2000
STP10243S

Chlorophyll Fluorescence as a Bioindicator of Photosynthesis Inhibition from Solar Ultraviolet Radiation in Plants and Algae

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Chlorophyll fluorescence is a simple, rapid technique for measuring photosynthetic efficiency in plants and algae. Pulse-amplitude modulated chlorophyll fluorescence was examined in aquatic plants and natural assemblages of Lake Erie phytoplankton exposed to solar ultraviolet (UV) radiation. UV-exclusion studies were performed in which plastic films were used to screen sunlight to remove ultraviolet-B radiation (295–320 ran), or UVB plus ultraviolet-A radiation (320–400 nm) in outdoor aquatic microcosms and ship exposure chambers. UV had negligible impacts on photosynthesis and growth in the aquatic macrophyte Myriophyllum spicatum in microcosms. However, photosynthetic electron transport in natural assemblages of Lake Erie phytoplankton was substantially diminished by short exposures to full sunlight. Phytoplankton exposed to full sunlight for 30 min lost 90 % of maximum photosystem II efficiency (Fv/Fm) and 75 % of the effective yield of photosystem II photochemistry (ΔF/Fm). Diminished photosynthetic electron transport was primarily due to UVB wavelengths in sunlight. UVA and visible wavelengths also diminished photosynthetic electron transport to a lesser extent. Thus, this assay represents a general bioindicator of effects from environmental stress in freshwater plants and algae that is able to detect impacts due to current and increasing levels of UVB.

Author Information

Marwood, CA
University of Waterloo, Waterloo, Ontario, Canada
Dobson, E
Centre for Toxicology, University of Guelph, Guelph, Ontario, Canada
Smith, REH
University of Waterloo, Waterloo, Ontario, Canada
Solomon, KR
Centre for Toxicology, University of Guelph, Guelph, Ontario, Canada
Greenberg, BM
University of Waterloo, Waterloo, Ontario, Canada
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Developed by Committee: E47
Pages: 27–39
DOI: 10.1520/STP10243S
ISBN-EB: 978-0-8031-5448-3
ISBN-13: 978-0-8031-2886-6