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First teaching 2025

First exams 2027

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Coral Reef Case Study (Cambridge (CIE) IGCSE Geography) : Revision Note

Jacque Cartwright

Written by: Jacque Cartwright

Reviewed by: Bridgette Barrett

Updated on

Why the Great Barrier Reef is important

Background

  • The Great Barrier Reef is one of the most important natural systems on Earth

  • Located off the coast of Queensland, Australia, it is the largest coral reef system in the world

  • It covers over 344,400 km2 — about the size of Japan!

Map of Australia showing key locations including Queensland, Canberra, and the Great Barrier Reef highlighted as a World Heritage Site along the northeast coast.
Location of the Great Barrier Reef

Biodiversity

  • It supports about 9,000 known species, including:

    • 1,500 species of fish

    • 400 species of coral

    • 6 species of sea turtles

    • 30 species of whales and dolphins

    • Over 130 species of sharks and rays

Economic value

  • The reef contributes more than AU$6 billion (about US$4 billion) to the Australian economy each year through tourism, recreation, and fishing, supporting over 64,000 jobs

Coastal protection

  • The reef system acts as natural walls that absorb wave energy, protecting coastal towns from erosion and storm damage

Cultural significance

  • Indigenous Australian groups like the Yirrganydji and Gurang people have cared for the reef for thousands of years, using traditional ecological knowledge

Threats to the Great Barrier Reef

Climate change

  • Rising sea temperatures stress corals, causing them to expel the algae (zooxanthellae) that give them colour and nutrients

  • This turns the coral white — a process called coral bleaching

  • If bleaching lasts too long, the coral can die

  • In 2016 and 2017, the reef experienced back-to-back bleaching events, damaging over 50% of shallow water corals in the northern and central sections

Runoff

  • When it rains, water from farmland, towns, and cities runs into rivers and eventually into the sea

  • This water often contains pesticides, fertilisers, and sediments that:

    • Smother corals

    • Reduce sunlight

    • Encourage outbreaks of crown-of-thorns starfish by increasing algae (their food)

Development

  • Past, present and future development poses a threat to the reef

  • These are agriculture, mining, urbanisation, industrial development, port development, aquaculture and tourism development

    • Although tourism is vital for the economy, anchor damage, walking on coral, or building resorts too close to the reef can cause serious harm

Fishing and poaching

  • Overfishing reduces fish populations that are important for reef health (like herbivorous fish that eat algae)

  • Illegal fishing

    • Although most fishers obey the rules, some ignore the zoning laws or fish without permission, especially at night or in remote areas

    • This puts extra pressure on already vulnerable parts of the reef

    • Undermines conservation efforts, making it harder for authorities to track and manage fish stocks

    • Reduces fish populations and disrupts the food chain, affecting both predators (like sharks) and prey

  • Destructive practices, such as trawling, dynamite fishing, or using illegal nets, physically damage coral structures and sea beds

  • Incidental catch, also known as bycatch, is when fishers accidentally catch marine animals they didn’t mean to catch. These can include:

    • Turtles

    • Dolphins

    • Seabirds

    • Sharks and rays

    • Juvenile fish (too small to legally keep)

  • Many of these animals are protected or endangered, and some die even if they are released

    • Gill nets are a type of fishing net that traps fish by their gills

    • But they can also trap sea turtles, who drown if they can't reach the surface to breathe

    • In the past, turtle deaths were common in some parts of the reef and has now been banned in many areas, especially near turtle nesting beaches

Scale 

  • The Great Barrier Reef is vast

  • It is difficult to find enough funding, resources and people to protect the area

Species

  • Crown-of-Thorns Starfish (COTS)

    • This sea star eats coral polyps

    • When populations grow too large, they cause major destruction, especially in areas already stressed by climate change

    • Outbreaks have destroyed up to 40% of coral cover in some parts of the reef

Crown-of-thorns starfish  with pale, thorny arms resting among rocks under dim underwater lighting, highlighting its textured surface and unique appearance.
Crown of thorns starfish Photo by David Clode on Unsplash
  • Lionfish are native to the Great Barrier Reef and play a natural role in the reef's ecosystem

    • While they are not invasive species, lionfish prey on small fish and invertebrates, potentially disrupting the delicate balance of the reef ecosystem

Strategies to protect the Great Barrier Reef

  • The reef is a World Heritage Site and a Natural Wonder of the World – this provides lawful protection and global recognition for future generations

Reef 2050 plan

  • This is a long-term plan for reef sustainability

  • It aims to bring together governments, local communities and industries

  • It evaluates the reef's values and threats, directing professionals to the areas where management efforts are most needed

Reef water quality programs

  • Farmers receive support to reduce fertiliser use and plant vegetation buffers along rivers

  • The Reef 2050 Plan sets targets to reduce nitrogen by 60% and sediment by 25% by 2025

Education

  • Education and training is important for people like tour guides

  • Presentations on reef protection regularly show at the Marine Park Authority Office 

  • Regular research is carried out to assess management strategies and their effectiveness

  • Universities in Queensland offer courses for coral research

Tools 

Great Barrier Reef Marine Park Authority (GBRMPA)

  • Established in 1975, GBRMPA is the main government agency responsible for protecting the reef

  • It works with scientists, traditional owners, communities, and industries to create and enforce rules that support sustainable use such as

    • Patrol boats and aerial surveillance to catch illegal fishers

    • Heavy fines and gear confiscation as punishment

    • Education campaigns to teach local fishers about sustainable practices

    • Satellite tracking on commercial fishing boats

    • There are also community-based programs where local people report suspicious activity — these help protect remote reef areas where it’s hard to patrol regularly

Zoning plans

  • The reef is divided into zones that allow or restrict certain activities

    • Green Zones, also known as No-Take Zones, where no fishing and collecting is allowed

    • General Use Zones allow some fishing and tourism, under strict rules

    • About 33% of the reef is now fully protected from all fishing

Permits

  • Most activities require a permit, e.g. tourism, infrastructure construction, boating 

Policies

  • Environmental, scientific and tourist government policies are set in place

Balancing stakeholders

Tourism management

  • Balancing the importance of tourism while protecting the reef

  • Guidance on managing reef tourism 

  • Future plans for tourism to be ecological as well as respectful to the heritage of the area

Heritage management

  • Respecting Aboriginal ownership of land and knowledge of the area

  • Working with Aboriginals and Torres Strait Islanders to protect the reef together

  • Training, programs, mapping and action plans

Science management 

  • Using scientific evidence to guide management practices

Monitoring and early warning

  • Scientists use satellites, drones, and underwater robots to monitor reef health

  • The Eye on the Reef app allows locals and tourists to report changes or threats they see

  • Fluker posts involve tourists in monitoring strategies

    • Tourists use these posts to take pictures of the reef

    • Photos are transferred to a site for professionals to examine

    • Cost-benefit – this saves money and time for workers

Species protection and control

  • Some species have different levels of protection (international, national, state or local)

    • This means they have lawful protection 

  • Species are also separated into threatened, at-risk or iconic

  • Some species must be controlled due to their negative impact, such as crown-of-thorns starfish outbreaks

    • Professional divers inject starfish to kill them (without harming the environment) 

Reef restoration

  • Heat-resistant corals and coral nurseries

    • Scientists are developing ‘super corals’ that can survive warmer water

  • Coral nurseries grow healthy corals which are then planted back onto damaged reefs — this is known as coral gardening

    • Coral fragments – collecting and taking fragments and then planting them elsewhere (underwater or onshore in tanks)

AWAITING IMAGE

The process of coral gardening to restore reefs

Traditional management

  • Indigenous People are using traditional and modern tracking methods to track animals like turtles 

  • There is a priority for subsistence fishing, limiting overfishing

  • Some areas of the reef are taboo, increasing protection

  • Some areas of the reef belong to Indigenous Groups 

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Jacque Cartwright

Author: Jacque Cartwright

Expertise: Geography Content Creator

Jacque graduated from the Open University with a BSc in Environmental Science and Geography before doing her PGCE with the University of St David’s, Swansea. Teaching is her passion and has taught across a wide range of specifications – GCSE/IGCSE and IB but particularly loves teaching the A-level Geography. For the past 5 years Jacque has been teaching online for international schools, and she knows what is needed to get the top scores on those pesky geography exams.

Bridgette Barrett

Reviewer: Bridgette Barrett

Expertise: Geography Lead

After graduating with a degree in Geography, Bridgette completed a PGCE over 25 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.

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