🌊 Case Study A: Great Barrier Reef Marine Park, Australia (HIC)
The Great Barrier Reef stretches for 2,300 kilometres along the coast of Queensland, north-eastern Australia. It is the world's largest coral reef system — home to 1,500 species of fish, 4,000 types of mollusc, 240 species of birds, and six of the world's seven species of marine turtle. In 1981, UNESCO designated it a World Heritage Site. In 2016, its coral began to die in the largest bleaching event ever recorded.
The Threats
Coral bleaching from ocean warming: In 2016 and 2017, back-to-back mass bleaching events killed approximately 50% of the reef's shallow-water coral. Bleaching occurs when ocean temperatures rise just 1–2°C above the summer maximum: the coral ejects the algae (zooxanthellae) living in its tissue, turns white, and — if temperatures remain elevated — starves and dies. The 2016 event was directly linked to climate change compounded by an El Niño warming event.
Water quality from agricultural run-off: Sugar cane and cattle farming in Queensland's coastal hinterland generates run-off containing sediment, nitrogen fertilisers and pesticides. This reduces water clarity (limiting the sunlight coral needs for photosynthesis), stimulates algae blooms that suffocate coral, and introduces pesticides toxic to coral larvae.
Crown-of-thorns starfish: This large, coral-eating starfish undergoes population explosions — partly triggered by excess nitrogen in the water — that can destroy large areas of reef. A single outbreak of crown-of-thorns can reduce coral cover by 90% in an affected area.
Tourism damage: 25 million tourist visits per year bring boats, divers, and physical disturbance. Anchors damage coral directly; sunscreen chemicals have been found to inhibit coral larvae development; some operators have historically allowed tourists to stand on or touch coral.
The Management Response
The Great Barrier Reef Marine Park Authority (GBRMPA) was established in 1975 and manages the reef under a comprehensive zoning system. The 344,400 km² park is divided into eight zones with different permitted activities:
Preservation zones (least disturbed areas): no entry permitted except for scientific research with special permission
Marine national park zones: no fishing, no collecting — snorkelling, diving and boating permitted
Habitat protection zones: some fishing and collecting permitted under licence
General use zones: most activities permitted including commercial fishing
In 2004, the no-take zones were expanded from covering 4.5% of the park to 33% — one of the largest marine protected area expansions in history. Studies have found that fish biomass inside no-take zones is 50–60% higher than in comparable fished areas.
The Reef 2050 Water Quality Improvement Plan aims to reduce agricultural run-off by 50% by 2025, using financial incentives for farmers to adopt lower-impact practices (reduced fertiliser use, vegetated riparian buffers along waterways). Coral restoration programmes breed heat-resistant coral varieties in nurseries and transplant them onto bleached sections of reef.
Evaluation: Effective — But Fighting the Wrong Battle?
What the management HAS achieved: 25 million tourists annually generate AUD $6.4 billion per year for the Queensland economy and provide a powerful economic incentive to protect the reef. No-take zones have demonstrably increased fish populations. Water quality improvement has reduced some agricultural pressure. The reef is better managed than almost any comparable marine ecosystem in the world.
What the management CANNOT achieve: Local management cannot fix a global problem. The primary threat — ocean warming from climate change — is caused by CO₂ emissions from every country on Earth. GBRMPA cannot reduce global temperatures by zoning the reef. The Australian government's own outlook report in 2019 downgraded the reef's long-term outlook from "poor" to "very poor" — despite the management framework.
The key exam judgement: The Great Barrier Reef Marine Park demonstrates that local management can be highly sophisticated and genuinely effective at reducing local pressures. But it also demonstrates the fundamental limitation of local management when the primary threat is global. Without international action on climate change, coral bleaching will continue regardless of how well the reef is managed locally. This is a critical evaluation point that separates Level 3 answers from Level 2.
