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Environmental Threats to the Great Barrier Reef
Because of the diversity, complexity, and uniqueness of the ecosystem, the Great Barrier Reef was placed under the protection of the Australian federal parks system, was named a World Heritage Site in 1981 and has been called one of the Seven Natural Wonders of the World. Still, life in the Reef is at risk.
One of the greatest threats to the Great Barrier Reef is climate change, also known as global warming. Three times over the last ten years, the water in the seas surrounding the Great Barrier Reef has risen 1 or more degrees Celsius. While this may not seem that significant, any temperature increase threatens the coral reefs. When the water becomes warmer , coral become stressed. This stress causes them to force Zooxanthellae, an algae living in coral shells essential to the sustenance of the coral polyp, out of their shells. Without this algae, the coral is unable to use photosynthesis to form its color which is why the phenomenon is known as “coral bleaching”. Once the algae are absent, the coral’s white skeleton shows and the coral begins dying, stops reproducing and becomes vulnerable to disease. The Great Barrier Reef experienced episodes of coral bleaching in 1998, 2002 and 2006. Scientists estimate that the 2002 temperature increase caused 60 to 95% of the Reef’s coral to become bleached. Because water temperatures are likely to continue to rise, researchers predict that episodes of coral bleaching will continue to occur. Therefore, the Great Barrier Reef Marine Park Authority has formed a response plan aimed at detecting and responding to future occurrences.
Crown of Thorns Starfish
Another natural threat to the Great Barrier Reef is the Crown of Thorns Starfish. This creature which is a naturally occurring species feeds on coral. While a small number of starfish pose no major threat to the vast collection of coral reefs, when they rapidly multiply, they place the Reef at risk. Eradicating these creatures (by forcing them to migrate out of the area) takes anywhere between 1 and 15 years.
Over the last 40 years, there have been three major outbreaks of Crown of Thorn Starfish. During those periods large portions of the coral reefs were damaged. These outbreaks combined with episodes of coral bleaching have had dramatic impacts on the coral forming the foundation of the Great Barrier Reef as well as threatening marine and bird species living in the Reef
Not all of the destruction of the Great Barrier Reef has come from natural sources. Human actions have also negatively impacted the area. Water pollution has threatened life in the Reef. A series of rivers feed the sea where the Reef is located. These rivers have flooded farm lands upstream siphoning large amounts of pesticides used on cattle and sugar cane farms surrounding the rivers. These waters then empty into the seas polluting the waters that the ecosystem.
In addition, land development poses risks to the Great Barrier Reef. Because of its beauty and diversity, the area attracts a huge number of visitors. Though the Reef is protected by the Australian Parks Authority, the tourism industry has built up commercial areas on the lands surrounding the area. This coastal development threatens the delicate ecosystem adjacent to it.
Beyond this, boats have damaged the Reef. Fishing boats have stripped the area of a number of key species of fish including the Giant Triton. While fishing of certain types of fish has been limited, the boats legitimately fishing in the area pose a potential threat to the entire collection of life located in the Great Barrier Reef. Because the boats carry large amounts of oil necessary for their operation, they always hold the possibility of creating a hazardous situation by spilling the oil into the area’s waters.
Based on the selection, which of the following is having the least negative effect on the Great Barrier Reef?
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