disturbances

Question 1

What is the role of coral polyps in reef formation?

Answer 1

Coral polyps build skeletons that form coral. They also contain algal symbionts that support the reef ecosystem.

Question 2

How can we characterize spatial and temporal variation in coral reefs?

Answer 2

By examining:

• Benthic community structure (% cover of hard corals)
• Species diversity
• Taxonomic community structure

Question 3

What processes structure coral reef ecosystems?

Answer 3

• Geographical location
• Temperature
• Depth
• Disturbances

Question 4

What is a disturbance in coral reef ecosystems?

Answer 4

A disturbance is an event that damages or kills residents at a given site. It can be classified as acute (short-term) or chronic (long-term). Frequent acute disturbances can form a chronic disturbance.

Question 5

What are the equilibrium hypotheses for explaining coral reef diversity?

Answer 5

• Niche diversification hypothesis
• Circular networks hypothesis
• Compensatory mortality hypothesis

Question 6

What are the non-equilibrium hypotheses for explaining coral reef diversity?

Answer 6

• Equal chance hypothesis
• Gradual change hypothesis
• Intermediate disturbance hypothesis (IDH) — diversity is highest at intermediate disturbance levels of frequency and intensity.

Question 7

What are some criticisms of the Intermediate Disturbance Hypothesis (IDH) for reefs?

Answer 7

• Empirical: Only 20% of 100+ studies show peak diversity at intermediate disturbance levels.
• Theoretical: Disturbances reduce species diversity, weaken competition, and alter the dominant competitor’s identity on an intermediate timescale.

Question 8

Should we abandon the Intermediate Disturbance Hypothesis (IDH) for reefs?

Answer 8

No. New evidence shows that disturbance-driven coexistence can occur via inter-species differences in size-dependent mortality, not just competition for space. This mechanism still supports the broader concept of intermediate disturbance promoting coexistence.