From earths orbit, the Great Barrier Reef looks like an ivory ribbon wrapping around the northeast coast of Australia. It is approximately equal in length to the west coast of the United States and is listed as one of the seven natural wonders in the world along with The Grand Canyon, Victoria Falls and Mount Everest. As one of the largest living organisms in our oceans, at over 2,300 kilometers long, 1,242 miles in length, the reef is unimaginable in size.
But size alone may not be enough to deter what is happening to the reef today.
Since its first discovery, The Great Barrier Reef has captured the imagination of many because of its immensity and rich abundance of aquatic life. Travelers have shared tales and written stories about the magic and the mystery surrounding life on the reef. Today tourist flock in large numbers to its warm waters to enjoy the Great Barrier Reefs beauty.
Due to its natural geological structure of shallow water, tidal movement and sunlight, the reef is also experiencing an ecological change of unknown proportion. What has enabled it to grow for millenniums may now be causing its rapid demise in our life time.
While some corals grow very slowly over hundreds of years, some grow very rapidly fed by the nutrients in the water. This dichotomy creates greater diversity.
Home to almost every imaginable living tropical ocean species in the world, one species has been taking advantage of the reefs abundance.
Since the early 1960’s, biologist following the behavior of a starfish known as The Crown of Thorns can see an infestation cycle occurring every one to fifteen years whereby they take over a sizable part of the reef destroying the corals they feed upon.
While not one of the top predators in the oceans, the Crown of Thorns may be one of the most efficient predators. It has the ability to pull its stomach out of its mouth while feasting on delicate coral polyps before using its many suction-cupped legs to slowly crawl away. One Crown of Thorns feeds upon 8 square kilometers of coral a year. It can survive without food for up to six months. Compound these numbers by hundreds of thousands.*
The infestation though, may not be a “natural” ecological phenomena at all, but instead, may be man caused.
Studies by marine scientists from the Australian Institute of Marine Science (AIMS) have found that reef over fishing results in the removal of top predators. In combination with mass tourism, an increase in agricultural run off from farms and along with coastal urban sprawl, the result is a rise in nutrient levels that feed starfish larvae. The final outcome being reefs over-stressed may take decades, if ever to rebound to a sustainable level.
Man’s proximity is suffocating the Great Barrier Reef.
What the Crown of Thorns may ultimately teach us is that there is a fading line between ‘what is natural . . .’ and the complex ecologically issues that continually question societies connection between nature and man.
The same rivers that feed water to farmlands and cities are the greatest suppliers of nutrients on the Great Barrier Reef creating high levels of phytoplankton—once again, food for the Crown of Thorns.
This population explosion invasion becomes more apparent shortly after a year of above average rainfall.
What the Crown of Thorns leaves behind is an absence of life—a white calcium carbonate skeleton similar to that of coral bleaching.
Coral bleaching occurs when a sudden rise in water temperature causes zooxanthellae to die. This symbiotic microscopic algae lives within coral tissues that photosynthesize giving corals color and at the same time absorbing waste and feeding polyps.
Since the majority of life on the Great Barrier Reef lives in the top 4 meters of water, an increase in water temperature of only 1.5-2℃ for six to eight weeks can have a devastating effect on the reef.
The shallow waters also result in other threats against the Great Barrier Reef.
In April last year a coal carrying ship from Queensland sailing to China went aground on the Great Barrier Reef. Australia is the world’s largest exporter of coal. China is the world’s largest importer of coal. The China owned freighter was 15 nautical miles outside designated shipping lanes in a restricted portion of the reef. Reports say that the ships first mate who hadn’t slept for almost two days was to blame.**
$1 million in fines were levied against the ships owners by the Australian authorities, $250,000 against the ships captain while emergency crews responded to the estimated 950 tonnes of heavy fuel oil that remained on the ship leaking from its punctured hull onto the surrounding coral reef.
In the end, damage to the reef was contained to a small section of the World Heritage site that may take up to twenty years to heal from the nearly three tonnes of fuel oil that spilled 3km onto the reef. Oil did reach a nearby island beach that is a rookery for nesting birds and sea turtles. Workers were able to unload the ships coal, refloat the vessel and tow it back to China where it was repaired.
While the Great Barrier Reef may be immense in size, we are constantly being reminded of how fragile it is. How much do we really understand about the biology of reefs if new discoveries are still being made today? The controversy will always continue between coral reef science, ecology and political environmentalism. These are issues facing us today, and at stake is our stability as human beings to live in accord with our environment.