About the Great Barrier Reef
We are all entrusted with the care of the Great Barrier Reef, home of the world’s most spectacular marine ecosystem. It is a piece of our heritage, something for the world to treasure, and must be passed on to future generations in good condition.
Stretching more than 2300 kilometres along Queensland’s coastline and covering 35 million hectares, the Great Barrier Reef is the world's largest coral reef, and probably the richest. More than 1500 species of fish, 4000 species of molluscs, 400 species of sponge and 300 species of hard corals live here.
Extensive seagrass beds provide a home for the threatened dugong. Threatened green and loggerhead turtles nest on islands in the reef, and humpback whales migrate there to give birth. Birdlife is also plentiful, and hundreds of species nest in the reef islands.
Queensland's first world heritage area, the reef is very important to Aboriginal and Torres Strait Islander people, and there are significant cultural sites on many of its islands.
The reef is very important in other ways. The World Heritage Area is worth some $5.4 billion to the Australian economy—$3.5 billion of that goes into the local towns and communities bordering the reef.
More than 67,000 people are employed in jobs like tourism, recreation and commercial fishing that depend on the health of the reef. Some 40,000 people are employed locally.
The reef is under pressure from:
- climate change
- poor water quality from land-based run off
- impacts from coastal development
- illegal fishing.
In recent years, a series of major storms and floods have affected an ecosystem already under pressure. Crown-of-thorns starfish outbreaks and marine debris are also affecting the area.
The reef is facing a range of threats over time, scale and duration – the accumulation of all impacts on the reef has the potential to further weaken its resilience.
This is likely to affect its ability to recover from serious disturbance such as major coral bleaching events which are predicted to become more frequent in the future.
The Great Barrier Reef experienced the worst mass coral bleaching event on record in the summer of 2015-16. Bleaching occurs when live corals are stressed, in this case from overheating.
The reef’s complexities are well described in the 2013 Scientific Consensus Statement. This science contributed to the updated Reef Water Quality Protection Plan (Reef Plan), which is a state and federal initiative designed to halt and reverse the decline in reef water quality. The consensus statement, developed by a multidisciplinary group of scientists and overseen by the Reef Plan Independent Science Panel, confirms that the major cause of coral cover loss is extreme weather events, such as cyclones. Clearly, we are not able to influence such events.
Progress towards the Reef Water Quality Protection Plan management practice and load reduction targets and inshore marine condition is detailed in an annual report card.
How water pollution affects the reef
Science indicates that most of this pollution comes from cattle grazing and sugarcane growing, as these are the most common industries in the reef catchments.
Nutrients from fertilisers and sediment (soil washed into waterways) lost from agricultural properties promote higher concentrations of microscopic algae, or phytoplankton, which is the food source for young crown of thorns starfish—most likely the cause of reef coral loss over the past 30 years.
Sediments and increased algal growth block light, critical for coral and seagrass to survive. Nutrients stimulate larger algae, like seaweed, to grow, covering coral and hindering its regrowth after cyclones and other disturbances. Sediment carries nutrients and toxic chemicals, and smothers coral, preventing coral larvae settling.
Scientists are seriously concerned about the effect on inshore reefs of some agricultural pesticides that work by blocking photosynthesis, the process by which plants and coral access the light-energy they need for survival.
Reef protection regulations
To help improve reef water quality outcomes, there are reef protection regulations for sugarcane and grazing properties in the high priority catchments Wet Tropics, Burdekin and Mackay Whitsundays.