title: Development of a toxicity identification evaluation protocol using chlorophyll-a fluorescence in a marine microalga.
abstract: Growth inhibition bioassays with the microalga Nitzschia closterium have recently been applied in marine Toxicity Identification Evaluation (TIE) testing. However, the 48-h test duration can result in substantial loss of toxicants over time, which might lead to an underestimation of the sample toxicity. Although shorter-term microalgal bioassays can minimize such losses, there are few bioassays available and none are adapted for marine TIE testing. The acute (5-min) chlorophyll-a fluorescence bioassay is one alternative; however, this bioassay was developed for detecting herbicides in freshwater aquatic systems and its suitability for marine TIE testing was not known. In this study, a chlorophyll-a fluorescence bioassay using the marine microalga Isochrysis galbana was able to detect contaminants other than herbicides at environmentally relevant concentrations and tolerated the physical and chemical manipulations needed for a Phase I TIE. Phase I TIE procedures were successfully developed using this chlorophyll-a fluorescence bioassay and used to identify all classes of contaminants present in a synthetic mixture of known chemical composition. In addition, TIEs with both the acute fluorescence bioassay and the standard growth inhibition bioassay identified the same classes of toxicants in a sample of an unknown complex effluent. Even though the acute chlorophyll-a fluorescence end point was less sensitive than the chronic cell division end point, TIEs with the chlorophyll-a fluorescence bioassay provided a rapid and attractive alternative to longer-duration bioassays.
authors.affiliation: Institute for Water and Environmental Resource Management, University of Technology, Sydney, P.O. Box 123, Broadway, NSW 2007, Australia. David.Strom1@csiro.au
authors.forename: D
authors.initials: D
authors.lastname: Strom
authors.forename: P J
authors.initials: PJ
authors.lastname: Ralph
authors.forename: J L
authors.initials: JL
authors.lastname: Stauber
mesh_terms: D001681:Biological Assay / Q000379:methods*; D002734:Chlorophyll / Q000737:chemistry* / Q000378:metabolism; D017377:Diatoms / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods; D005453:Fluorescence; D023382:Toxicity Tests, Acute / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015262:Xenobiotics / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D015262:Xenobiotics; D002734:Chlorophyll