STP1403

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

    Published: Jan 2000


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    Abstract

    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.

    Keywords:

    Plants, ultraviolet radiation, microcosms, phytoplankton, chlorophyll fluorescence, photosynthesis, bioindicator


    Author Information:

    Marwood, CA
    Post-doctoral fellow, professor, and professor, University of Waterloo, Waterloo, Ontario

    Dobson, E
    Research technician and professor, Centre for Toxicology, University of Guelph, Guelph, Ontario

    Smith, REH
    Post-doctoral fellow, professor, and professor, University of Waterloo, Waterloo, Ontario

    Solomon, KR
    Research technician and professor, Centre for Toxicology, University of Guelph, Guelph, Ontario

    Greenberg, BM
    Post-doctoral fellow, professor, and professor, University of Waterloo, Waterloo, Ontario


    Paper ID: STP10243S

    Committee/Subcommittee: E47.01

    DOI: 10.1520/STP10243S


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