Although the World Heritage listed The Great Barrier Reef as
a “dynamic system” where the coral populations naturally increases and decreases,
human activities have significantly accelerated the death of coral reefs, leaving
little room for them to recover (Phillips, 2012). The rise in ocean temperature
and acidification has led to the death of the organisms residing inside the
coral skeleton, also known as coral bleaching, accounting for 10 percent of
coral reef decline (Phillips, 2012). Global warming models show how higher
water temperatures are also leading to more severe cyclones, which accounts for
48 percent of coral die off (Phillips, 2012). Coastal development and agricultural
runoff has led to a significant increase in the amount of sediments, nutrients,
and pesticides entering the ocean, causing algal blooms (Hoegh-Guldberg et al. 2004:32). This intensification
of nutrients from runoff leads to the rise in crown of thorn starfish larvae
survival due to the abundance of algae that the larvae consume (Phillips, 2012).
Although the crown of thorn starfish is a natural predator of coral reefs, they
are multiplying so quickly that the reef does not have enough time to recover
from damage (Phillips, 2012). The crown of thorn starfish outbreak accounts for
42 percent of The Great Barrier Reef coral wipeout. In the past 27 years, over
50 percent of The Great Barrier Reef coral has been wiped out and if nothing is
done in the next ten years only 25 perfect of the coral reef will remain
(Phillips, 2012).
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This is a chart taken from an article in The Age, an Australian daily broadcast newspaper. http://www.theage.com.au/environment/conservation/great-reef-catastrophe-20121002-26vzq.html |
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An image of a thorn starfish outbreak eating coral. Credit: Katharina Fabricius, Australian Institute of Marine Science http://www.livescience.com/23611-image-gallery-great-barrier-reef-through-time.html |
In addition
to the destruction of coral, wildlife populations have also been significantly
damaged due to unsustainable fishing methods and marine based pollution (Hoegh-Guldberg et al. 2004:32).
Destructive fishing methods such as trawling for prawns is allowed in over one
third of the Great Barrier Reef and leads to bycatch and seafloor destruction
(WWF, 2012) Other destructive fishing methods such as cyanide and dynamite
fishing also destroy the coral and reef wildlife (Hoegh-Guldberg et al. 2004:32). Overexploitation of
fish has led to an imbalance in the ecosystem. The fish are key predators and
prey in the coral reef food chain and when their population is significantly
reduced, the population of the organisms they fed on drastically increase while
the organisms that fed on the fish dramatically decrease (Hoegh-Guldberg et al. 2004:32). Coastal
developments have led to an increase in pollution and chemicals that are dumped
into the ocean, which then accumulate and poison corals and organisms (Hoegh-Guldberg et al. 2004:32). The
disposal of plastic bags in the ocean not only suffocates marine wildlife but
also prohibits photosynthesis by blocking the sun (Hoegh-Guldberg et al. 2004:32). The dangerous fishing
and disposal practices from human exploitation of these coral reefs have
serious affects on not only the coral but also the marine life.
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This is an illustration of the destructive effects of ecosystem overfishing. Credit: John Michael Yanson
Source: Adapted from Pauley et al., 1998; Goni, 2000
http://see-the-sea.org/topics/commerce/overfishing.htm
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This image of the horseshoe reef shows the destruction of the reef by crown of thorn starfish. The left side of the image is the before the outbreak and the right side is an image after the destruction.
Credit: AIMS Long-Term Monitoring Team
http://www.pbs.org/newshour/multimedia/before-after-aims/2.html |
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This image of the MacDonald reef shows the before (left) and after (right) a tropical cycle damaged the coral reef.
Credit: AIMS Long-Term Monitoring Team
http://www.pbs.org/newshour/multimedia/before-after-aims/index.html |
Sources:
1. "Great Barrier Reef." WWF
Australia. WWF, 2012. Web. 30 Nov 2012. <http://www.wwf.org.au/our_work/saving_the_natural_world/oceans_and_marine/priority_ocean_places/great_barrier_reef/>.
2. Hoegh-Guldberg,
Hans, and Ove Hoegh-Guldberg. " Implications of Climate Change for the
Australia’s Great Barrier Reef.” WWF
Australia. (2004): 32. Web. 30 Nov. 2012.
<http://awsassets.wwf.org.au/downloads/cl029_great_barrier_reef_2050_the_implications_of_climate_change_1fev04.pdf>.
3. Phillips,
Nicky. "Great reef catastrophe." Age [Melbourne,
Australia] 2 10 2012, Web. 30 Nov. 2012. <http://www.theage.com.au/environment/conservation/great-reef-catastrophe-20121002-26vzq.html>.