title: Herbicide impact on Hormosira banksii gametes measured by fluorescence and germination bioassays.
abstract: The innovative bioassay described here involves chlorophyll a fluorescence measurements of gametes from the macroalgae, Hormosira banksii, where gametes (eggs) were exposed to Diuron, Irgarol and Bromacil. Response was assessed as percent inhibition from control of effective quantum yield (DeltaF/Fm') of photosystem II, herein referred to as % PSII Inhibition. This was measured with the dual-channelled pulse amplitude modulated (PAM) fluorometer, ToxY-PAM. The fluorescence bioassay was run simultaneously with an established H. banksii germination bioassay to compare sensitivity, precision, and time-to-result. The fluorescence bioassay gave highly sensitive results evidenced by EC(50)s (% PSII Inhibition) for Diuron, Irgarol and Bromacil being three, four and three orders of magnitude (respectively) lower than EC50s generated from the germination bioassays. Precision of the fluorescence bioassay was demonstrated with low coefficient of variations (<30%) for all three toxicants. With regard to time, the fluorescence bioassay gave results within 6h, as opposed to more than 50h for the germination bioassay.
authors.affiliation: Institute for Water and Environmental Resource Management, Department of Environmental Sciences, University of Technology, Sydney, Westbourne Street, Gore Hill, 2065 NSW, Australia.
authors.forename: Cliff R
authors.initials: CR
authors.lastname: Seery
authors.forename: Leanne
authors.initials: L
authors.lastname: Gunthorpe
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ralph
mesh_terms: D001681:Biological Assay / Q000379:methods; D001976:Bromouracil / Q000031:analogs & derivatives / Q000633:toxicity; D002734:Chlorophyll; D000077194:Chlorophyll A; D004237:Diuron / Q000633:toxicity; D005453:Fluorescence; D005854:Germ Cells / Q000187:drug effects*; D006540:Herbicides / Q000633:toxicity*; D000459:Phaeophyceae / Q000187:drug effects*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000032:analysis; D018675:Toxicity Tests; D014227:Triazines / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D006540:Herbicides; D045332:Photosystem II Protein Complex; D014227:Triazines; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; C103341:irgarol 1051; D001976:Bromouracil; D004237:Diuron; C004590:bromacil; D000077194:Chlorophyll A