River carrying silt. Photo: AIMS

The Great Barrier Reef has an interdependent relationship with the adjacent land, the Great Barrier Reef catchment. The flow from the Catchment to the Reef is not simply downstream, but also involves migrations of many species, such as fish, between coastal marine waters, rivers and creeks and wetlands.

The rivers draining the catchment carry suspended sediments, nutrients and pollutants into the waters of the GBR coastal zone.

Coastal water quality is adversely affected by:

Water quality sampling. Photo: AIMS

• Vegetation clearing leading to soil erosion and sediment and nutrient run-off
• Run-off of agricultural fertilisers, pesticides, toxic chemicals, sewage, rubbish, detergents, heavy metals and oil
• Acidic run-off and leaching from excavated acid sulfate soils along the coast
• Clearing, filling, and draining of wetland areas, reducing their role as natural filters for land run-off
• Poor stormwater management
• Alterations to the environment by development activities along the coast
• Introduction of non-native or non-local marine species by shipping and aquaculture activities

There have been community concerns for many years about the potential impacts of elevated nutrient and sediment loads on the marine communities of the Great Barrier Reef. Multi-disciplinary projects supported by CRC Reef Research Centre have increased knowledge about the fate of nutrients and sediments derived from Queensland's rivers, and their impacts on inshore coral and algal communities. These results are being used to set regional water quality guidelines, and to support liaison with agricultural industries to ensure best-practice in agricultural and catchment management planning.

For more information about the impact of land use on the Great Barrier Reef, and current CRC Reef research, see:

• CRC Reef's brochure summarising the impact of Land Use and the Great Barrier Reef (June 2003)

• Current CRC Reef research into the impacts of runoff to the Great Barrier Reef World Heritage Area including the Catchment to Reef project - a joint initiative between CRC Reef and Rainforest CRC

• Catchment to Reef: water quality issues in the Great Barrier Reef region (pdf 863k) Conference abstracts (March 2004) available as CRC Reef Technical Report No. 53

• Report from CRC Reef Water Quality Monitoring workshop (November 2002)

• A 2001 scientific review by Dr David Williams (CRC Reef and the Australian Institute of Marine Science) that draws together and integrates scientific information on the Impacts of terrestrial run-off on the Great Barrier Reef World Heritage Area

• A consensus statement by 18 scientists that summarises scientific understanding about impacts of terrestrial runoff on the Great Barrier Reef World Heritage Area

• Dr Miles Furnas has published a book which is the first comprehensive description of the state of the Great Barrier Reef catchment, modern levels of runoff to the reef, and the influence on runoff on coastal reef ecosystems. Catchments to Corals: Terrestrial run-off and the Great Barrier Reef (published 2003)

• CRC Reef researchers have modelled the flow of 10 rivers into the Central and Northern Section of the Great Barrier Reef Shelf

• A previous report Modelling the impact of the Burdekin, Herbert, Tully and Johnstone River plumes on the Central Great Barrier Reef (pdf 2MB) is available as CRC Reef Research Centre Technical Report No. 4