Ecotoxicology of pesticides on the Great Barrier Reef for guideline development and risk assessments

Andrew Negri

Led by: Dr Andrew Negri, AIMS


Project Summary

Over 50 land-sourced pesticides have been detected in waters of the Great Barrier Reef (GBR) and its catchments. Previous studies on the risks posed by pesticides have focused on five priority PSII herbicides. However, other pesticides are increasingly being used, for which there are few fate, persistence and toxicity data. In order to improve water quality guidelines and assessments of the potential risks posed by these “alternate” pesticides to GBR and its catchments we will quantify their toxicity to freshwater and marine species.

Problem Statements


The management of land-sourced pesticide contamination in the GBR and its catchments is a priority for achieving targets intended to improve water quality and halt the decline of the Great Barrier Reef (GBR) (LTSP 2015, Kroon et al. 2016b, Reef Plan 2016). At a global scale, the GBR and its catchments represent some of the best monitored tropical waters, with over 50 pesticides detected in waters of this region (O’Brien et al. 2016). Monitoring and reporting has focused on the five priority PSII herbicides that are detected more frequently than other pesticides (Reef Plan 2016). The risks posed by these herbicides are better understood than the risks associated with other pesticides, as the former were the focus of previous toxicity, fate and persistence research (Devlin et al. 2015). The detection of a suite of “alternate” pesticides (pesticides other than the five priority PSII herbicides) in the GBR and its catchments (Wallace et al. in press) has resulted from changes in land management practices, restriction in the use of some PSII herbicides and improved monitoring technologies (O’Brien et al. 2016). Although reductions in total PSII herbicide loads in riverine and marine systems have been reported (Waters et al. 2014), there are little relevant data on the toxicity, fate and persistence on the alternate pesticides. Recent desktop assessments suggest at least some of these alternate herbicides pose similar (if not greater) environmental risks than more commonly applied chemicals (Davis et al. 2014).

The Problem: In order to effectively manage potential risks posed by alternate pesticides to tropical freshwater and marine ecosystems, we need improved knowledge of the ecotoxicity of alternate pesticides to relevant freshwater and marine species.

How Research Addresses Problem

We will quantify the toxicity of priority and alternate pesticides detected in the GBR and its catchments. The pesticides will be selected in consultation with stakeholders, building upon the existing toxicity database being compiled by DSITI and DEH for the development of species sensitivity distributions (SSD) for both freshwater and marine species. GBRMPA, APVMA and the Department of Environmental and Energy will also be consulted on the selection of pesticide targets to maximize the application of data across end-users.

The toxicity tests will be performed in accordance with new criteria for deriving water quality guidelines (Warne et al. 2015), allowing them to directly feed into development of: (i) National (ANZECC, including contributions from EHP Project RP129) and GBR ecosystem protection guidelines; (ii) toxic equivalency values; (iii) toxic loads and multisubstance-potentially affected fraction (ms-PAF) values.

The data will also be available to contribute to the revision of metrics for pesticide monitoring and reporting for: (i) QLD Regional Report Cards; (ii) Reef Plan 2013; (iii) Great Barrier Reef Report Card; (iv) Reef 2050 Long Term Sustainability Plan (LTSP); (v) regional Water Quality Improvement Plans (WQIP); (vi) chemical risk assessments for pesticide registration and review (e.g. the Department of the Environment and Energy conducts for the APVMA); (vii) relative risk assessments for alternate pesticides (for on-ground decision making by industries) and (viii) ecological risk assessments including the Scientific Consensus Statement.

Alignment with NESP Research Priorities

NESP Priority 1c. Examine the fate, persistence and exposure characteristics of existing and/or alternate pesticides used in GBR catchments, in freshwater and marine environments, to develop water quality/ecotoxicity guidelines and to support ecological risk assessments. Specify the rationale or process for pesticide selection.

Project Keywords

Pesticide; Toxicity; Great Barrier Reef; Tropical; Runoff.

Project Funding

This project is jointly funded through AIMS, JCU, UQ, DSITI, GBRMPA and the Australian Government’s National Environmental Science Programme.

Project Publications






Project Map

Click on a marker for larger map

Markers are not an exact position of where the research is taking place, they are only to be used as a guide to the general area in which it is being carried out.