Water quality and crown-of-thorns starfish on the Great Barrier Reef

High severity. Serious, widespread effects requiring sustained action. Severity is descriptive editorial metadata summarising documented effects. It is not a measured index or a score.

1. 01

   Agricultural runoff

   Fertiliser, sediment and pesticides from sugarcane and grazing lands.

2. 02

   Land clearing and erosion

   Loss of vegetation increases sediment runoff.

3. 03

   Starfish outbreaks

   Crown-of-thorns starfish populations periodically explode.

1. 01

   Reduced coral cover

   Starfish outbreaks and poor water quality reduce coral.

2. 02

   Slower recovery

   Degraded water quality slows recovery after bleaching or cyclones.

3. 03

   Seagrass loss

   Sediment reduces light for seagrass meadows.

1. Improved farm practices

   Reducing fertiliser use, stabilising gullies and restoring wetlands.

   Expected effectReduces pollutant loads reaching the reef.

2. Crown-of-thorns control

   Targeted culling by trained divers.

   Expected effectProtects coral on priority reefs.

3. Catchment monitoring

   Paddock-to-reef monitoring and reporting.

   Expected effectTracks progress toward water quality targets.

No reliable quantitative indicator is included for this issue. TerraLens shows figures only where a credible source supports them — consult the sources below for current data.

1. [1]Great Barrier Reef Marine Park AuthorityAustralian Governmentgbrmpa.gov.au(opens in a new tab)
2. [2]Department of Climate Change, Energy, the Environment and WaterAustralian Governmentdcceew.gov.au(opens in a new tab)

Links open the publishing organisation's site. Some point to the publisher's main page, where the named report or dataset can be found.