Human Impacts on Coral Reefs: Six Major Threats

Coral reefs cover <0.1% of ocean floor but support 25% of marine species. Human actions are driving their collapse:

1. Overfishing (esp. herbivores): Removes algae grazers → macroalgae smother corals.
2. Pollution: Nutrient runoff (fertilizers, sewage) → eutrophication & algal blooms; sediments smother; plastics & toxins poison.
3. Climate Change: Warming → mass bleaching (expulsion of zooxanthellae); acidification (↓pH) → slower calcification, weaker skeletons.
4. Coastal Development: Dredging, reclamation, marina construction destroy habitat & increase turbidity.
5. Destructive Fishing: Blast fishing, cyanide, muro-ami pulverize reef framework.
6. Unsustainable Tourism: Anchoring, trampling, sunscreen chemicals (oxybenzone), fish feeding disrupt ecology.

Solutions

• Marine Protected Areas (no-take zones)
• Watershed management (reduce runoff)
• Climate mitigation (1.5°C target)
• Restoration (coral gardening, larval propagation)
• Reef-safe tourism standards

Reefs can recover if pressures ease. The window is closing.