This activity helps children understand how coral bleaching affects reef ecosystems and the fish that depend on healthy coral for protection from predators. Through movement and role-play, students experience how marine habitat degradation impacts small reef fish survival.

Preparation

1. Clear a large open space in the classroom or use the playground/hall.

2. Place green paper "healthy coral" across the floor with some space between pieces.

3. Keep white paper "bleached coral" ready to substitute during the activity.

4. Use blue tape to mark the boundaries of the "coral reef" area.

Activity Steps

1. Gather students and explain that they are going to be small fish living on a coral reef. Show quick images of healthy coral and bleached coral side by side. Explain that healthy coral has many colors and provides hiding places for small fish. When the water gets too warm, coral turns white or 'bleaches' and doesn't protect fish as well.

2. Assign roles:

• Most students will be damselfish (small reef fish)

• 1-2 students will be groupers (predator fish)

• Optional: 2-3 students as observers who will report what they see

3. Explain the rules:

• Damselfish are safe when touching green coral (they can rest there)

• Damselfish are vulnerable when near white coral (they can pass by but not rest)

• Groupers try to tag damselfish when they're not touching green coral

• Tagged damselfish sit out until the next round

Round 1: Healthy Reef

1. Start with many green coral pieces spread across the area

2. Have damselfish move around the reef, using green coral as safe zones

3. Allow groupers to hunt, but damselfish can easily find safety

4. Play for 2-3 minutes.

Round 2: Partially Bleached Reef (3 minutes)

1. Pause the activity and replace about half of the green coral with white coral

2. Tell students: "The ocean is warming, and some coral is beginning to bleach"

3. Restart the activity with fewer healthy coral pieces

4. Damselfish can move past white coral but cannot use it as a safe zone

Round 3: Severely Bleached Reef (3 minutes)

1. Pause again and replace most remaining green coral with white coral

2. Tell students: "The ocean has gotten even warmer, and more coral has bleached"

3. Restart the activity with very few healthy coral pieces

4. Have damselfish try to survive with limited safe zones

Role Rotation (Optional)

If time allows, rotate roles so more students can experience different perspectives

Activity materials

• 15-20 green paper sheets/objects to represent healthy coral

• 15-20 white paper sheets/objects to represent bleached coral

• Blue masking tape to create a "reef area" on the floor

• Optional: simple fish headbands/paper fish shapes for children playing damselfish

• Optional: shark/grouper mask or hat for the predator

• Timer or stopwatch

• Whistle or other sound maker to signal transitions

Coral reefs are vibrant underwater ecosystems that provide food and shelter for many marine species. Small reef fish, such as damselfish, rely on healthy coral to hide from predators. However, when ocean temperatures rise, corals experience bleaching, losing their color and becoming weaker (Hughes et al., 2017). This means fewer safe hiding spots for fish, making them more vulnerable to predators.

Corals have tiny algae living inside them that give them their color and provide them with food. When the ocean gets too warm, corals become stressed and expel the algae, turning white (Hughes et al., 2017). Bleached corals are weaker and struggle to support the marine life that depends on them. If temperatures stay high for too long, the coral may die, leading to less shelter and food for fish.

Scientists have observed widespread coral loss due to ocean warming, with significant spatial variability. Some regions, like the Great Barrier Reef, have suffered multiple mass bleaching events in recent decades (GBRMPA, 2020). Meanwhile, some reefs in deeper or cooler waters have been more resilient. The Intergovernmental Panel on Climate Change (IPCC) warns that if global temperatures rise by 1.5°C above pre-industrial levels, up to 90% of the world's coral reefs could be lost (IPCC, 2018).

Coral bleaching has been observed to have knock-on impacts on the fish that call the reef home, including:

• Less Shelter – Small fish use coral as hiding spots to escape predators. When corals bleach, they lose their structure, leaving fish exposed (Pratchett et al., 2008).
• Fewer Food Sources – Many reef fish eat the tiny organisms that live around healthy coral. When coral dies, food becomes scarce.
• More Predators – Without coral to hide in, small fish are easier targets for larger fish (Graham et al., 2007).

By experiencing these challenges firsthand in the activity, students will better understand the importance of coral reefs and how climate change impacts ocean life.