Coral Bleaching

Environment   Oct 11, 2016 by Lily Hunt

Coral Bleaching

As many are unaware of, climate change has an extremely large influence on coral reefs. Living on the doorstep of the reef, this issue has reached visible consequences on Australia's coral. Changes in the global climate patterns have greatly attributed to the increasing levels of atmospheric carbon dioxide. This warmer climate and ocean surface temperatures negatively impact coral reefs, resulting in coral bleaching.

Corals are marine organisms which are very sensitive to change in climate, where global warming’s heat stresses the corals. Scientists have said that coral bleaching is a poorly-understood type of "stress" related to high irradiance due to high water temperatures, and, for Australia, it reflects how the high sea temperatures affect the reef.Temperatures remaining high for four weeks or more, with only slight variation, trigger events amongst the corals. When this occurs, the photosynthetic algae zooxanthellae, that lives within their tissue, is expelled from the corals.

Zooxanthellae produces a source of oxygen and assists the coral in removing wastes but, most importantly, supplies the coral with glucose, glycerol, and amino acids (products of photosynthesis). Corals depend on this algae but, when ocean temperatures increase for consecutive weeks, the zooxanthellae removes itself from the tissue. Without zooxanthellae, corals lose their colour. Unhealthy, white corals are referred to as bleached, as they are weak and less able to fight off diseases.

If temperatures remain at a constant high degree for longer than an eight week period, corals begin to die, affecting regional reefs on the global scale.

Statistics

In 2002, GBRMPA, the Great Barrier Reef Marine Park Authority, recorded that only 35% of corals were unaffected. In 1998, only four years difference to the second data recording, there were 45% of corals unaffected, meaning 10% more of corals were affected. In this time, 5% of corals were considered ‘damaged’ but did not increase any further when 2002’s data was collected.

In 1998, it began with 50% of corals were bleached. In 2002, 60% of corals were bleached, being the largest coral bleaching event on record. This was until in 95% of corals were bleached in 2015, with the possibility of being unable to recover.

How does coral bleaching affect Australia?

Coral bleaching will have a major toll on Australia’s tourism, particularly North Queensland, as there is little appeal to visit a dying reef, or one with little to no colour. This will affect Australia’s economy, and therefore influences other parts of the country.

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