Sediment and Particulate Nutrients

IN BRIEF:

The presentation outlines sediment and particulate nutrients

• Land-derived sediment and nutrient export to the Great Barrier Reef has increased 1.4 to 5 times since European arrival, with high variability between basins.
• Increased sediment delivery reduces light availability for benthic organisms like seagrass and coral reefs.
• Management is most effective when targeted to sediment and nutrient hotspots, which occur in various land uses and erosion processes like gully, streambank, and hillslope erosion.
• The Burdekin River is the single largest contributor of fine sediment to the Great Barrier Reef, contributing about 40% of the total load.
• Sediment from the Burdekin can be traced hundreds of kilometres offshore, with the fine fraction less than 20 microns travelling the furthest and influencing water quality.
• Seagrass meadows in Cleveland Bay have declined in area and biomass after major flood events, likely due to sediment and nutrient impacts.
• Key management approaches include targeting hotspot areas for gully, streambank, and hillslope erosion control, maximising ground cover, and retaining existing vegetation.