Quick questions on Great Barrier Reef case study: HSC Geography 2022 Focus Area

The reef shows clear cross-shelf and along-shelf zonation. From the Queensland coast outward: coastal estuaries and mangroves; inshore turbid waters; mid-shelf reefs; outer-shelf reefs at the edge of the continental shelf; and beyond the shelf the deep waters of the Coral Sea. Along the latitudinal gradient from south to north, sea-surface temperature, rainfall and adjacent catchment land use vary, producing distinct northern, central and southern sectors.

The reef supports a very high marine biodiversity, including a large number of coral species, fish species, marine turtles (green, loggerhead, hawksbill, flatback, olive ridley, leatherback all use the region), dugongs, marine mammals and seabirds. Published assessments cite hundreds of coral species and well over a thousand fish species; precise counts vary in published surveys.

Reef-building corals are colonial cnidarians that host symbiotic algae (zooxanthellae of the genus Symbiodiniaceae) inside their tissues. The algae photosynthesise and provide most of the coral's energy in normal conditions. When sea-surface temperatures rise above a threshold sustained for too long, the algae are expelled and the coral whitens (bleaches).

The reef has experienced repeated mass bleaching events linked to marine heatwaves:

Native to the reef but undergoes periodic population outbreaks that consume coral. Outbreaks are linked in part to nutrient runoff (which boosts plankton on which COTS larvae feed) and partly to natural cycles. COTS control is a major management activity.

Catchment land use in the Burdekin, Fitzroy, Mackay-Whitsunday, Wet Tropics and Cape York regions delivers sediment, nitrogen, phosphorus and pesticides into the reef lagoon. Sediment reduces light reaching corals; nutrients drive algae overgrowth and may boost COTS larval survival.

Tropical cyclones (which the reef has always experienced but which may be intensified by climate change); shipping incidents; outbreaks of coral disease; illegal fishing; coastal development.

GBRMPA is the federal agency responsible for managing the Marine Park. It is jointly responsible with the Queensland state agency for management of the broader Great Barrier Reef World Heritage Area.

The Marine Park is divided into a multiple-use zoning plan, first introduced in 1981 and most recently substantially revised in 2003-2004 (the 2003 Representative Areas Program). Zones include general use, habitat protection, conservation park, no-take marine national park (green zones), preservation zones, and special-purpose zones. The 2003-2004 rezoning substantially increased the share of the Marine Park in highly protected (no-take) zones.

The Reef 2050 Plan is a joint Australian and Queensland Government plan for the future of the reef, first released in 2015 and updated subsequently. It sets goals and actions across themes including ecosystem health, biodiversity, heritage, water quality, community, economic benefits and governance.

A subordinate plan focused on reducing sediment, nutrient and pesticide runoff from agricultural catchments through grazing land management, sugar-cane best practice, and revegetation. Progress is independently reported and is uneven across pollutants and catchments.

A targeted COTS culling and monitoring program operates on priority reefs.

Traditional Owners have connections to the Great Barrier Reef extending over many thousands of years. Sea Country Plans developed with Traditional Owner groups (including Gunggandji, Yirrganydji, Wuthathi, Mandubarra and many others) inform management. GBRMPA's Traditional Use of Marine Resources Agreements (TUMRAs) recognise and support Traditional Owner use and management of sea country.

The dominant emerging driver, ocean warming, is global. No local management action can prevent ocean heatwaves; reducing the rate of warming requires global greenhouse-gas mitigation under the UNFCCC and Paris Agreement. Strong evaluations note this asymmetry: GBRMPA can build reef resilience by managing local pressures, but cannot fix the dominant pressure.

Describe the biophysical features of the Great Barrier Reef and identify its current World Heritage status. [4 marks]