Student Exploration: Coral Reefs 1 – Abiotic Factors
Directions: Follow the instructions to go through the simulation. Respond to the questions and
prompts in the orange boxes.
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. Look at the graph to the right. What does it show?
percentage of coral cover in Caribbean Reefs. It shows a
decline over time.
2. Why do you think corals have declined since 1977?
people are killing and selling them
Gizmo Warm-up
Coral reefs are some of the most diverse habitats on Earth, home to over
a quarter of all marine species. The Coral Reefs Gizmo provides a
simplified model of interactions among 10 key species in Caribbean reefs.
In the Coral Reefs 1 exploration, you will focus on the effects of
environmental factors on Caribbean reefs.
1. Click Advance year 10 times. Look carefully at the composition of the
reef over time. Do you see any major changes?
the reef stayed consistent
2. Select the DATA tab. Check that Staghorn coral, Star coral, Sponges, and Algae are selected.
Populations are given as a percentage of normal populations. What do you notice about these populations?
sponges population goes up while the others don’t
3. On the right side of the Gizmo, select the SUMMARY tab. In a healthy reef, what are the values for
Nutrient load, Water clarity, Coral cover, and the total number of fish species?
Nutrient 4ppt Water 94% Coral 49% Total fish 442
load: clarity: cover: species:
, Get the Gizmo ready:
Activity A:
● On the CONDITIONS tab, click Return to original
The Caribbean
settings. Click Restart.
reef ecosystem
● Select the CORAL REEF tab.
Introduction: A healthy Caribbean reef is home to over 50 species of coral and over 400 fish species. In this
simplified model, we only consider the interactions of ten important species.
Question: How do different species interact in a healthy coral reef?
1. Describe: On the CORAL REEF tab, click on each organism shown in the table below. For each organism,
give its name and what it eats (or how it obtains energy).
Picture Name What it eats (or how it obtains energy)
staghorn coral photosynthetic symbiotic algae
boulder star coral photosynthetic symbiotic algae
sponge eat plankton in the water
algae photosynthesis
stoplight parrotfish eats algae
queen angelfish eats sponges
yellow snapper eats young fish, shrimp, crabs, and worms
nassau grouper eats reef fish like snapper, angelfish, and parrotfish
long-spined sea urchin eats algae
hawksbill sea turtle eats sponges
2. Corals obtain energy from tiny photosynthetic algae, called zooxanthellae, which live inside the coral’s
tissue. How do you think corals would be affected by cloudy, muddy water?
if the water is cloudy then the algae can’t absorb sunlight which kills the coral
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