PADI Divemaster Certification Practice Exam

Which factor is not a major threat to coral reefs?

1. Overfishing

2. Coastal land filling

3. Excess sunlight

4. Chemical pollutants

The correct answer is: Excess sunlight

Excess sunlight is not a major threat to coral reefs compared to the other factors listed. Coral reefs thrive in clear waters with adequate sunlight, as this is essential for the photosynthetic process performed by zooxanthellae, the symbiotic algae living within the coral. These algae rely on sunlight to produce energy, which is then utilized by the coral for growth and nourishment. On the other hand, overfishing significantly disrupts the ecological balance of coral reef systems by eliminating key species, which can lead to an overabundance of algae and less competition for resources. Coastal land filling results in habitat destruction and increased sedimentation, which can smother corals and reduce the amount of light that reaches them. Chemical pollutants can introduce harmful substances into the reef environment, affecting the health of the coral and the overall ecosystem. Therefore, while excess sunlight is necessary for the health of coral reefs, the other options pose serious threats to their survival.