An independent panel of experts has compiled existing scientific knowledge of how dredging and disposal impacts on the Great Barrier Reef.

Brought together under a joint initiative of the Great Barrier Reef Marine Park Authority and the Australian Institute of Marine Science, the panel reviewed information on the physical and biological effects of dredging and disposal.

The panel's report titled Synthesis of current knowledge of the biophysical impacts of dredging and disposal on the Great Barrier Reef summarises what is known about the effects of dredging, what is scientifically contentious, and the key gaps in our knowledge.

Consisting of 19 technical and scientific experts, the panel represented a broad range of skills, experience and perspectives — from oceanographic modelling to coral ecology.

• Among its key findings, the report concluded:
• In terms of direct effects, dredging and burial of seafloor habitats during disposal can have substantial impacts at a local level, but have only a small impact on the broader Great Barrier Reef and its biodiversity as a whole.
• In terms of indirect effects, sediments released by dredging and disposal have the potential to stay suspended in the water and move. This may be contributing significantly to the long-term chronic increase in fine suspended sediments in inshore areas, however there wasn’t consensus among the panelists on the extent to which this happens and its impact on biodiversity.
• Dredging and disposal may be a significant source of fine sediments in the World Heritage Area, in addition to other sources, such as land run-off. A general comparison shows that past large dredging projects produced amounts of fine sediment similar in magnitude to natural loads coming from land run-off in the same region.
• The recent policy commitments to ban disposal of capital dredge material in marine environments will mean future disposal, which will be limited to maintenance dredging, will contribute much less fine sediment. This reduced amount will still need to be considered in the context of other cumulative impacts on the Great Barrier Reef.
• The knowledge gaps identified by the panel are likely to guide further research into the effects of dredging and disposal.

Improving our understanding of the effects of dredging will also help us further develop policy and best practice guidelines.

All management actions are based on best available knowledge — it is part of our adaptive management approach to ensure this knowledge is updated.

Project scope

This work focuses on physical, chemical and ecological aspects such as how sediment moves, settles and disperses and looks at ecological impacts on reefs, seagrass and other key species and habitats.

Although the social, economic, cultural and heritage aspects of dredging are important, these are beyond the scope of this phase of the project.

• The expert panel was formed on an agreed set of criteria, ensuring a broad range of relevant skills and expertise.
• Coral ecology and impacts: Dr Ross Jones from Australian Institute of Marine Science
• Seagrass ecology and impacts: Dr Michael Rasheed from James Cook University
• Dredging, corals and seagrasses: Dr Paul Erftemeijer, a consultant
• Fish habitat: Prof. Marcus Sheaves from James Cook University
• Seafloor habitats: Dr Roland Pitcher from CSIRO
• Megafauna and species of conservation interest: Prof. Helene Marsh from James Cook University
• Hydrodynamic modelling: Dr Richard Brinkman from Australian Institute of Marine Science
• Hydrodynamic modelling: Dr Brian King, a consultant 
• Hydrodynamic modelling: Dr Andy Symonds from Royal HaskoningDHV
• Water quality: Mr Jon Brodie from James Cook University
• Sediment biogeochemistry, distribution and movement: Prof. Brad Eyre from Southern Cross University
• Pollutant biogeochemistry: Dr Simon Apte from CSIRO
• Pollutant biogeochemistry: Dr Michael Warne from Queensland Government
• Engineering, dredging and port operations: Mr Frans Hoogerwerf, a consultant     
• Engineering, dredging and port operations: Dr Rick Morton, a consultant
• Policy and environmental impact management: Dr Ray Masini from Western Australia Government    
• Policy and environmental impact management: Dr Ian Irvine, a consultant 
• Dr Britta Schaffelke from Australian Institute of Marine Science   
• Panel coordinators and science – policy transfer: Dr Laurence McCook from 
• Great Barrier Reef Marine Park Authority

Criteria for selecting dredge synthesis panel

The following statement was circulated to partner organisations, stakeholders and Traditional Owners at the beginning of the dredge synthesis project to outline how panel members would be selected.

Panel membership will be based on scientific or technical expertise of strong relevance to the scope of the project. The scope of the project is limited to the biophysical impacts of dredging and spoil disposal within the Great Barrier Reef Region. Panel membership will not be based on representation of different sectors or interests.

Panellists must have current, demonstrated relevant scientific and/or technical experience, including but not limited to:

• Experience with the biophysical impacts of:
• dredging
• dredge spoil disposal in the marine environment
• sediment dynamics, hydrodynamics, biogeochemistry of sediments in the Great Barrier Reef.

• Had recent research experience with stressors related to:
• turbidity
• light limitation
• sedimentation
• pollutants and contaminants associated with dredged sediments
• effects on corals and reefs, seagrass meadows, and other relevant Great Barrier Reef habitats, especially inshore habitats.

Panel membership will be limited in numbers, ideally to 15 or less, but with a maximum of 20, depending on the range of skills, experience and availability of nominated experts.

Nine expert panellists have already been invited. Final membership will aim to reflect a range and diversity of technical and scientific perspectives and expertise.

Finalisation of the panel membership will be made by the panel convenors, Dr Laurence McCook and Dr Britta Schaffelke, with input from senior management at Great Barrier Reef Marine Park Authority and the Australian Institute of Marine Science.

Whilst suggestions and input have been sought from a wide range of stakeholders and Traditional Owners, Great Barrier Reef Marine Park Authority and Australian Institute of Marine Science reserve the right to nominate final panel membership without further negotiation.