Flowing through the Ranger uranium mine lease and into Kakadu National Park, Magela Creek is home to important populations of native fish species that need to be able to move between the river, floodplain and escarpment country at different times of the year. Fish movement around floodplains during the wet season facilitates the transport of large amounts of nutrients and energy from floodplains to creeks as flood waters recede. This process supports important food sources for Traditional Owners and protects the World Heritage values of the Park.
Weathering of waste rock from the mine releases contaminants, including magnesium sulfate. These contaminants are washed out by the rain and are predicted to move through the local groundwater towards Magela Creek. Depending on the concentration, the magnesium sulfate (a salt) has the potential to affect fish, trees and other ecosystems in and near Magela Creek downstream from the Ranger mine site.
The Ranger uranium mine is due to cease operations by 2021 and this study is leading to better knowledge about how mining waste-related salty plumes may affect ecological processes and connectivity. Researchers are studying fish migrations in the Magela Creek catchment to determine the extent to which magnesium sulfate plumes could interfere with fish movements and related ecological functions and processes. They are also recommending ongoing monitoring and evaluation activities to inform mine closure activities and trial new-generation monitoring equipment and infrastructure.
This project is:
- investigating fish movement and abundance in Magela Creek and its floodplain at different times of year
- determining the risks to fish movement from current magnesium sulfate concentrations in Magela Creek from regulated releases of mine tailings water
- analysing the future risks to fish movement from magnesium sulfate contamination
- informing mine rehabilitation options and monitoring activities
- improving our understanding of tropical food web dynamics by using the Magela Creek findings to build on previous work.
Project activities
- Tag 100 fish with acoustic transmitters to characterise their seasonal movements between the floodplain and refugial billabongs
- Use imaging sonar to generate near-video-quality images of fish to observe their behaviour and estimate their abundance
- Deploy underwater video cameras to obtain species-level information on fish abundance and migration
- Quantify the biomass transported between floodplains and main channel habitats by fish migration
- Link fish movement data to models of surface and groundwater movement and literature review findings
- Quantify responses of migrating fish to current approved mine water releases.
Anticipated outputs
- A conceptual model of how different fish species use the creek based on quantitative information
- An assessment of the risks to Magela Creek fish species associated with mine waste water
- A report outlining future ecological risks and options associated with rehabilitation of the Ranger uranium mine site and downstream areas
- Recommendations for a monitoring program and ongoing assessment of potential impacts to fish communities from the predicted salty water
- Scientific papers and summary factsheets.
Fieldwork is taking place in Magela Creek, both upstream and downstream from Ranger uranium mine.
Hub research in NT’s Magela Creek is increasing our understanding of whether fish in the freshwater creek move differently in the presence of salty mine wastewater.
This project is being led by Associate Professor David Crook from Charles Darwin University (CDU). A/Prof Crook is being assisted by researchers from CDU and the Supervising Scientist Branch of the Department of Agriculture, Water and the Environment.
Contact
David Crook, Charles Darwin University
[email protected]
Northern Hub news (November 2019)
Northern Australia November 2019 update. As end of the Hub draws nearer, this eNews updates you on how we are […]
Do mine-water discharges affect fish movement?
The project team investigating fish movement and sensitivity to contaminated mine water in the Top End’s Magela Creek have been […]
Northern Hub news (November 2018)
Northern Australia November 2018 update. With 2018 drawing to a close, this eNews introduces you to 10 new projects that […]
Informing Ranger mine rehabilitation
The NT’s Ranger uranium mine is set to cease operations in 2021 and by 2026, be rehabilitated to a state […]
Research marketplace
Please join us at our research marketplace workshop on 13 November as part of the Territory NRM conference in Darwin. […]
Tree water use & sensitivity to contaminated mine water
Riparian, or riverbank, vegetation in the Top End depends on groundwater to sustain it during the dry season. Weathering of waste rock […]
Does contaminated mine wastewater affect fish movements?
The Ranger uranium mine is due to cease operations in 2021 and the site will be rehabilitated by 2026. Knowledge […]
Northern Hub News (May 2018)
Northern Australia May 2018 update. As we pass the halfway point of the Hub’s lifespan, our eNews reflects on our […]
