Additive toxicity of herbicide mixtures and comparative sensitivity of tropical benthic microalgae

Marie E. Magnusson, Kirsten Ruth Heimann, Pamela A. Quayle, Andrew Peter Negri

Research output: Contribution to journalArticlepeer-review

112 Citations (Scopus)


Natural waters often contain complex mixtures of unknown contaminants potentially posing a threat to marine communities through chemical interactions. Here, acute effects of the photosystem II-inhibiting herbicides diuron, tebuthiuron, atrazine, simazine, and hexazinone, herbicide breakdown products (desethyl-atrazine (DEA) and 3,4-dichloroaniline (3,4-DCA)) and binary mixtures, were investigated using three tropical benthic microalgae; Navicula sp. and Cylindrotheca closterium (Ochrophyta) and Nephroselmis pyriformis (Chlorophyta), and one standard test species, Phaeodactylum tricornutum (Ochrophyta), in a high-throughput Maxi-Imaging-PAM bioassay (Maxi-IPAM). The order of toxicity was; diuron>hexazinone>tebuthiuron>atrazine>simazine>DEA>3, 4-DCA for all species. The tropical green alga N. pyriformis was up to 10-fold more sensitive than the diatoms tested here and reported for coral symbionts, and is recommended as a standard tropical test species for future research. All binary mixtures exhibited additive toxicity, and the use of herbicide equivalents (HEq) is therefore recommended in order to incorporate total-maximum-load measures for environmental regulatory purposes.

Original languageEnglish
Pages (from-to)1978-1987
Number of pages10
JournalMarine Pollution Bulletin
Issue number11
Publication statusPublished - Nov 2010


  • Fluorometry
  • Great Barrier Reef
  • Herbicide
  • Photosynthesis
  • Pollution


Dive into the research topics of 'Additive toxicity of herbicide mixtures and comparative sensitivity of tropical benthic microalgae'. Together they form a unique fingerprint.

Cite this