Great Barrier Reef

The Great Barrier Reef lies in the Coral Sea, off the north-eastern coast of Queensland, Australia. It stretches for roughly 2,300 kilometres along the coast. The name refers to a connected, changing natural system rather than a single continuous wall of coral: the region includes thousands of separate reefs as well as islands, cays, lagoons, coastal habitats and open water.

Two boundaries are often confused. The Great Barrier Reef Marine Park covers about 344,400 square kilometres, while the UNESCO World Heritage property covers about 348,000 square kilometres. The park makes up most of the listed property, but the terms are not interchangeable. The Marine Park also includes a range of habitats beyond coral reefs.

The Great Barrier Reef Marine Park includes around 3,000 coral reefs, 600 continental islands, 300 coral cays and about 150 inshore mangrove islands. Coral reefs themselves account for only a small part of the park; the rest includes seagrass, mangroves, sand and algal habitats, sponge gardens, inter-reef areas and deep oceanic waters. These connected environments support a broad range of plants and animals.

The Reef Authority lists about 450 types of hard coral, 1,625 types of fish, six marine turtle species and more than 30 species of whales and dolphins. UNESCO describes the World Heritage property as an exceptionally extensive reef ecosystem with hundreds of coral types and many other marine animals.

The Reef is Sea Country for Aboriginal and Torres Strait Islander peoples. The Great Barrier Reef Marine Park Authority recognises about 70 Traditional Owner groups with connections to the region and describes their custodianship and cultural relationships as continuing. The Authority reports evidence of Sea Country connections extending back around 60,000 years.

Traditional use of marine resources can include fishing, collecting, hunting and caring for cultural places. These practices are part of living cultures and are managed through laws and agreements that recognise Traditional Owners' rights and support sustainable use. Traditional knowledge and participation also contribute to stewardship of the Reef.

The Great Barrier Reef Marine Park Act 1975 established the Marine Park and its protection framework. UNESCO inscribed the Great Barrier Reef on the World Heritage List in 1981, recognising the site's natural significance, including its ecological diversity and geological development. The Marine Park is a multiple-use area: conservation operates alongside activities such as tourism, shipping and fishing, with zoning and other management measures governing where and how activities occur.

The Great Barrier Reef Marine Park Authority is responsible for managing the federal Marine Park. The Australian Institute of Marine Science (AIMS) conducts long-running surveys that help track reef condition. Its monitoring work examines coral cover, bleaching, disease, crown-of-thorns starfish and fish communities across reefs and regions, supporting research and management rather than treating the Reef as a uniform site.

The Reef experiences both natural disturbances and pressures linked to human activity. Cyclones, outbreaks of crown-of-thorns starfish and large freshwater inflows can affect reefs. Heat stress can cause corals to expel the microscopic algae with which many live; this bleaching can lead to widespread coral mortality when conditions are severe or prolonged. AIMS identifies increased sea temperature as the primary cause of regional mass bleaching and reports that climate change is increasing the frequency, intensity and extent of heat stress associated with bleaching.

Bleaching and other disturbances do not affect every reef in the same way. AIMS surveys reefs repeatedly across the Marine Park, measuring coral and fish communities and other indicators to distinguish local impacts from broader changes. Such long-term, region-wide observations are important for understanding both damage and recovery and for informing conservation decisions.