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

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!

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 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)

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