Human & Environmental impact
Coral Bleaching
One of the signs that a coral reef is being threatened is coral bleaching, which is when coral is whitened. Coral bleaching occurs when the algae that sustains a symbiotic relationship with the coral dies out. This can be caused by a number of different things, some of which are listed below.
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If coral is without its algae counterpart for a long period of time it may cause individual coral polyps to die or even the entire reef to die. Unfortunately since coral reefs are home to so many marine animals and plants, the loss of habitat would affect many species.
Ocean Acidity – Limestone is the building block of coral reefs and a very basic substance, so when it dissolves slowly it lowers the acidity of the water around a coral reef. With the rising acidity of the world's oceans more limestone is dissolving to help keep the pH levels of the oceans balanced. This leads to the coral reefs being damaged and is one of the environmental threats to the health of the Great Barrier Reef.
Crown of Thorns Starfish – This particular species of starfish is an invasive species in the Great Barrier Reef and can cause a lot of damage because it feasts on coral polyps. Originally the starfish was not invasive, but in the 20th century the predators (eg. Pacific Triton) of the starfish were overhunted. Without any predators to keep the population of the crown-of-thorns starfish under control, the starfish became a threat to the coral reefs.
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Rising Ocean Temperatures – Due to climate change the ocean temperatures are rising, especially surface water temperatures like those surrounding the Great Barrier Reef. Unfortunately even small shifts in temperature can cause coral bleaching. Rising ocean temperatures are considered one of the greatest threats to the Great Barrier Reef because of the extreme nature of climate change.
Tourism – After all we have learned it is hard to deny that the Great Barrier Reef is amazing, which is why so many people choose to explore the reef each year! The amount of tourists that visit each year is approximately 2 million. While this is a great way to boost economy and educate people on the natural wonders of the coral reef, it can be detrimental to the health of the reef if tourism is not carefully monitored. Controls must be in plae to prevent humans from walking on the coral, breaking off pieces of the reef as souvenirs, dropping anchors on the reefs and grounding boats on them, and dragging scuba gear across the coral.
