Related Experiment Video
Updated: Jul 14, 2026
08:49
Vegetated Treatment Systems for Removing Contaminants Associated with Surface Water Toxicity in Agriculture and Urban Runoff
Published on: May 15, 2017
10.9K
Toxicity of Herbicide Mixtures to Tropical Freshwater Microalgae Using a Multispecies Test
S Stone1,2,3, M S Adams2, J L Stauber2
1School of Earth, Atmosphere and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia.
Environmental Toxicology and Chemistry
|November 17, 2020
Summary
Pesticide runoff from agriculture contaminates Great Barrier Reef waters. A new microalgal toxicity test shows diuron and hexazinone herbicides harm freshwater algae, even at low environmental concentrations.
Area of Science:
- Environmental Toxicology
- Ecotoxicology
- Freshwater Ecology
Background:
- Agriculture in the Great Barrier Reef catchment area leads to pesticide contamination of freshwater ecosystems.
- These contaminated waters flow into the Great Barrier Reef World Heritage Area, posing a threat to its ecological integrity.
Purpose of the Study:
- To assess the toxicity of diuron and hexazinone herbicides to a community of tropical freshwater microalgae.
- To evaluate the effectiveness of a novel multispecies microalgal toxicity test for assessing herbicide impacts.
Main Methods:
- A novel multispecies toxicity test was employed using three tropical freshwater microalgae: Monoraphidium arcuatum, Nannochloropsis-like sp., and Pediastrum duplex.
- Toxicity of diuron and hexazinone, including commercial formulations, was determined using 10% inhibition concentration (IC10) values.
- Water samples from herbicide-contaminated Sandy Creek and a clean reference site were directly assessed for toxicity.
Main Results:
- Diuron was more toxic than hexazinone to all tested microalgae species.
- Commercial herbicide formulations did not show significantly increased toxicity due to additives.
- Toxic effects were observed in Sandy Creek water samples and in artificial herbicide mixtures at environmentally relevant concentrations.
Conclusions:
- The novel multispecies microalgal toxicity test is an effective tool for assessing herbicide toxicity in freshwater ecosystems.
- Diuron and hexazinone pose a risk to freshwater microalgal communities in the Great Barrier Reef catchment area.
- Understanding herbicide toxicity is crucial for protecting the Great Barrier Reef's water quality.
