Algae overgrowth is often caused by an influx of nutrients from sewage runoff. The algae then compete with the coral, preventing coral growth.

Anchoring often damages coral reefs.

Coral is delicate and can be easily broken when stepped on, smashed by boats that run aground, or even when hit by large waves.

Dead reef are becoming the norm in many areas. Ocean acidification makes it difficult for corals to build additional coral structures.

Pollution negatively impacts corals. Here, fishing line has been caught in the coral.

Coral disease is also taking a toll on many corals. This coral has been affected by White Syndrome, which some believe is more easily spread in rising ocean temperatures.

Overfishing can easily disrupt the harmony of an ecosystem. The predators of the Crown of Thorns Starfish have been over-fished, giving the starfish (on the left hand side) free reign to consume hundreds of coral each year.