Compared to pre-European conditions, the annual discharge of fine sediment loads to the Great Barrier Reef has increased approximately five-fold with grazing being the main contributor.
Graziers manage 31.1 million hectares of land and over 100,000 kilometres of streambank in the Great Barrier Reef catchments.
Increased sediment run-off primarily comes from grazing including gully and hillslope erosion (45%) and streambank erosion (39%).
Fine sediment comes from soil that is lost through hillslope, streambank and gully erosion. The lost soil ends up in local waterways and travels out to the Great Barrier Reef.
Erosion is a naturally occurring phenomenon often accelerated by human activity such as reducing or removing vegetation, such as grasses and trees, that exposes the soil and makes it vulnerable to movement.
Minimising erosion, retaining valuable topsoil and productive perennial pasture are achievable at the paddock scale and provide benefits for both graziers and the Reef.
In the long term (3-15 years), managing cattle in a way that maintains good land condition and improves degraded land will result in greater pasture productivity and is more profitable than continuous heavy stocking, with subsequent and inevitable declines in land condition.
What is the problem with sediment run-off?
Some of the impacts of sediment on Great Barrier Reef ecosystems include:
- interfering with filter feeding by organisms such as clams
- reducing coral recruitment
- altering the quantity and quality of light available for photosynthesis –– essential for growth of coral and plants such as seagrass
- smothering corals
- affecting the reproductive cycle and early development of coral and some species of fish.
Much of the sediment that is washed to the Reef is very fine and can stay suspended in the water for a long time, often travelling a great distance away from or along the coast.
Nutrients and other pollutants attached to sediments have the potential to be released in the marine environment and create problems for corals and seagrass.
Support programs and tools
There are a number of industry and government programs and support tools that can help graziers adopt best farming practices.
- Last reviewed
- 8 May 2023
- Last updated
- 8 July 2022