Threats to Coral Reefs

Handley et al (2007) Geography Focus Stage Four Pearson: Sydney. p92-3 and p98-9

Human impact on coral reefs, whether deliberate or through accident, neglect or ignorance, needs to be identified before we can manage or minimize its effects. Most threats to Coral Reefs are a direct result of human activities.

Trade in Coral Reef Animals The collection of both coral and reef fish for sale to aquarium enthusiasts is a serious threat to coral reefs. The global value of this industry is estimated at $500 million and consists of over 1000 reef species. Cyanide is used to stun the reef fish in the wild for their capture. The cyanide kills the coral polyps. Fishing Overfishing removes fish stocks and does not leave a large enough population of fish to restock the area, thus altering the ecosystem. Blasting for fish with dynamite allows for mass collection quickly, however it significantly effects the coral reef. Tourism Tourism is the world’s fastest growing industry. The creation of each resort affects the reefs by discharging the resort’s waste into the water. The increased number of visitors to the coral reef environments destroys the coral through careless tour operators in boats and other activities such as walking on the reef. Coastal Development It is estimated that ½ billion people live within 100kms of a coral reef. The growth of large cities along the coast places pressure on reefs as pollution from the urban areas enters the water and people exploit the resources of the reef. Farming Farming, logging and land clearing all lead to soil erosion. As it is washed into rivers, soil eventually ends up in the ocean. When rivers flow across farmland and empty into the sea near coral reefs the sediment and nutrients encourage algae and limit the sunlight necessary for coral polyps to grow, killing the reef. Risk of Destruction The risks to reefs can be broken down by their causes:- 36% due to over-exploitation; activities such as fishing and taking coral 30% due to coastal development; building near reefs 22% due to inland pollution; runoff from agriculture and towns 12% due to marine pollution; shipping debris and oil leaks Your Turn -  Convert the above data into a pie graph. Pest Infestations Changes in the balance of the reef ecosystem occur when nutrients from urban areas, septic tanks and agricultural activities enter the water. These nutrients encourage the growth of algae, which is the favoured diet of the crown of thorns starfish. This increased food supply causes starfish numbers to increase. When this happens it does not take too long before parts of the reef are destroyed due to the starfish’s preferred diet of coral polyps. Tropical Cyclones Cyclones form over the warm oceans. They are intense tropical storms that create large waves and big tides that are sometimes large enough to wash completely over coral cays.

Your Turn -  Use the Internet to locate a photograph of a crown-of-thorns starfish.

Study reveals cyclone damage to coral reefs 100 kilometres from eye of cyclone

When Tropical Cyclone Ingrid crossed the far “ The reef provided its own protection from northern Great Barrier Reef it left a trail of wave damage, leaving many corals in the destruction to 260 coral reefs across a path protected areas intact. These surviving corals over 200 kilometres wide. Researchers from will help restore the worse affected areas” Dr the Australian Institute of Marine Science Fabricius. (AIMS), such as Dr Katharina Fabricius, were keen to find out about the level of damage. Corals at the outer edge will probably take 2 – 3 years to recover, those at ground zero were “ We investigated the impact of seven types stripped bare and could take up to two decades to of cyclone damage to the reef; coral breakage, bounce back. movement of massive corals, stripping of soft Estimates from the Australian Bureau of corals, coral sand movement, scarring of coral Meteorology suggest that wind speeds reached at by debris, algal blooms, and removal of plants least 250 kilometres per hour and wave heights from the reef. as high as 10 metres occurred within the Great “ These surveys examine how wave damage Barrier Reef area. to coral communities differs between sheltered 17 August 2005 and exposed sites. The corals on outer reefs appear to be more resistant to breakage compared with the more fragile inshore reefs.

Comprehension Read the above newspaper article and respond to the following question. a. How many coral reefs were damaged by the cyclone? b. Name the seven types of cyclone damage to reefs the researchers investigated. c. What role will the surviving corals play in repairing the damage to the reef caused by the tropical cyclone? d. What was the wind speed and wave height caused by the cyclone? e. Why would these wind speeds and wave heights caused damage to the coral reef?

Research 1. Which is the most likely factors that cause 80% of the coral reefs of South-East Asia to be at high risk? Provide specific examples for your conclusions. 2. In April 2010 an oil tanker, The Shen Neng 1, crashed on the Great Barrier Reef off Great Keppel Island off the coast of Queensland. a) Describe the incident and the threat to the Coral Reef environment. b) Outline the management strategy of ‘green zones’ in minimizing the threat to the Coral Reef Environment. c) Recommend strategies to the Queensland Government to protect the reef against future accidents. Begin your research at the website – http://www.smh.com.au/environment/shipping-crackdown-urged-to-protect-reef-from-disaster- 20100404-rlry.html