What has threatened the Great Barrier Reef?

Answer 1

A number of factors threaten the Great Barrier Reef.

The Great Barrier Reef, like any natural habitat, faces numerous threats, largely as a result of human impact. Although it does not have an official listing of endangered, it is shrinking, and it is unknown by how much, or whether this is permanent. Climate scientists who subscribe to the theory of anthropogenic global warming (i.e. caused by man's activities) predict that the Great Barrier Reef may lose up to 95% of its coral by the middle of the current century. Although the coastline parallel to the Great Barrier Reef has been settled by Europeans for less than 200 years, these scientists believe that the Reef has been shrinking by 20% every 100 years.

Climate scientists who subscribe to the theory that global warming is cyclical perhaps have a less drastic view, as they believe that the coral will regenerate, as it has apparently done so in the past. There is evidence that the coral goes down much deeper than first thought, and this is an important factor in its regeneration. It is a very emotive topic.

Pollution and chemical runoff pose a very real threat to the reef. The water quality of the reef is affected by sediment and nutrients, and 80% of this is caused by cattle grazing on the land adjacent to the reef. Mud and chemical runoff tend to limit the sunlight that reaches the coral, causing it to die off, and they increase the macro-algae, which is a weed.

Tourism is a threat to the reef, as tourist boats damage the delicate framework of the reef; fishing and pollution left behind by visitors also is a threat.

A natural threat to the Great Barrier Reef is the Crown of Thorns starfish. Outbreaks of this starfish are a constant threat to the animals of the Great Barrier Reef, though in small numbers it poses no threat.

There are about 40 species which live in and around the Great Barrier Reef which are listed as endangered, mostly due to human impact.