Environmental Changes

What is coral bleaching?

Coral bleaching occurs when corals become stressed by warm water and expel the zooxanthellae algae living inside them, causing the coral to turn white.

What are zooxanthellae?

Tiny algae that live inside coral and provide food through photosynthesis while giving coral its colour.

What is the main cause of coral bleaching?

Rising ocean temperatures caused by climate change.

Where is the case study located?

The Great Barrier Reef, Queensland, Australia.

What type of environment is affected by coral bleaching?

Marine and coastal coral reef ecosystems.

Why is the Great Barrier Reef important?

It supports biodiversity, tourism, fishing, coastal protection and Indigenous cultural values.

How long is the Great Barrier Reef?

Over 2,300 km long.

Approximately how many individual reefs make up the Great Barrier Reef?

Around 2,900 reefs.

Approximately how many islands are in the Great Barrier Reef?

Around 900 islands.

Which sea is the Great Barrier Reef located in?

The Coral Sea.

Why do corals expel zooxanthellae?

Because they become stressed when ocean temperatures stay too high.

Is bleached coral dead?

No. Bleached coral is alive but weakened and may die if stressful conditions continue.

What is a marine heatwave?

A period of unusually high ocean temperatures lasting days or weeks.

What is climate change?

Long-term changes in Earth's climate mainly caused by increased greenhouse gas emissions.

Name four indirect causes of coral bleaching.

Greenhouse gas emissions, burning fossil fuels, pollution and ocean acidification.

How does ocean acidification affect coral?

It makes it harder for corals to build and maintain their skeletons.

How can pollution contribute to coral bleaching?

Pollution reduces water quality and places extra stress on corals.

How does agricultural runoff affect reefs?

It carries fertilisers and sediments into the ocean, reducing water quality.

Name one natural factor that can stress coral reefs.

El Niño, tropical cyclones or crown-of-thorns starfish outbreaks.

How has coral bleaching changed over time?

It has become more frequent and more severe.

What happened in 1998?

A major global coral bleaching event occurred.

Which years saw severe bleaching on the Great Barrier Reef?

2016, 2017, 2020, 2022 and 2024.

Name another place where coral bleaching occurs.

The Maldives, Hawaii, Indonesia or the Caribbean.

Name three environmental impacts of coral bleaching.

Coral death, biodiversity loss and habitat loss.

How does coral bleaching affect fish?

Fish lose shelter, food sources and breeding habitats.

How does coral bleaching affect biodiversity?

Fewer marine species can survive, reducing biodiversity.

How does coral bleaching affect food chains?

Loss of coral habitats disrupts marine food webs.

What are ecosystem services provided by coral reefs?

Coastal protection, tourism, fisheries and biodiversity.

Name two social impacts of coral bleaching.

Reduced tourism and impacts on Traditional Owners' cultural connections.

Name two economic impacts of coral bleaching.

Loss of tourism income and impacts on fishing industries.

Why is tourism affected by coral bleaching?

People are less likely to visit damaged reefs.

How does coral bleaching affect coastal protection?

Damaged reefs absorb less wave energy, increasing coastal erosion.

Who manages the Great Barrier Reef Marine Park?

The Great Barrier Reef Marine Park Authority (GBRMPA).

Name two government organisations involved in protecting the reef.

GBRMPA and the Australian Government.

What is a marine protected area?

An area where human activities are managed to protect marine ecosystems.

What is the purpose of fishing restrictions?

To protect fish populations and reef ecosystems.

What is coral restoration?

Growing and transplanting healthy corals onto damaged reefs.

What is a coral nursery?

A place where young corals are grown before being placed onto reefs.

Why do scientists monitor reef temperatures?

To detect bleaching risks early.

Name four management strategies.

Protection, prevention, restoration and adaptation.

What is prevention in reef management?

Reducing greenhouse gas emissions and pollution before damage occurs.

What is protection in reef management?

Using marine parks, zoning and fishing restrictions.

What is restoration in reef management?

Repairing damaged reefs using coral nurseries and transplantation.

What is adaptation in reef management?

Helping reefs cope through monitoring and reducing other stresses.

Are current management strategies completely effective?

No, because climate change continues to increase ocean temperatures.

What is the biggest limitation of current management?

Global climate change.

Why are coral restoration projects limited?

They are expensive and only cover small areas.

What role do Traditional Owners play?

They use Indigenous knowledge to help care for Sea Country.

What could happen if current trends continue?

More frequent bleaching, coral loss and declining biodiversity.

Name three future management strategies.

Reduce emissions, improve water quality and expand coral restoration.

Why is reducing greenhouse gas emissions important?

It addresses the main cause of coral bleaching.

Which management strategy is the most important long-term?

Reducing global greenhouse gas emissions.

Define biodiversity.

The variety of living organisms in an ecosystem.

Define sustainability.

Meeting today's needs without preventing future generations from meeting theirs.

Explain the coral bleaching process in order.

Warm water → Coral stress → Algae expelled → Coral turns white → Coral weakens → Coral may die.

What is the strongest evidence linking climate change to bleaching?

Increasing frequency of mass bleaching events as ocean temperatures rise.

Why is the Great Barrier Reef vulnerable?

It is highly sensitive to warming oceans and repeated marine heatwaves.

What are the three types of impacts you should discuss in Geography?

Environmental, social and economic.

Which factor causes the greatest long-term threat to the Great Barrier Reef?

Climate change.

Which answer structure should you use in the validation?

Point → Evidence → Explain.

Which four management categories should you remember?

Protection, Prevention, Restoration and Adaptation (PPRA).

What is the easiest way to remember the causes?

Climate change → Warmer oceans → Marine heatwaves → Coral bleaching.