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Tropical islands surrounded by coral reefs are an idyllic getaway, but its own popularity is threatening this habitat.

Reefs & Resorts

Coastal development can damage nearby coral reefs. Construction debris can smother coral and introduce nutrients which encourage weedy algae to take over the reef. These threats are magnified if mangroves or other ecosystems that trap sediment are removed during development.

 How coastal development threaten coral reefs Water Clarity

One of the first steps in coastal development is preparation of the building site. Vegetation is removed and the land is excavated to provide a suitable base to build on. This creates sediment which, without proper precautions, can wash into streams or rivers and dump onto a nearby reef.

Sediment threatens the coral reef ecosystem in several ways:

  • Debris smothers the reef
  • Increased nutrients encourages algal growth
  • Water clarity is reduced
  • Vital ecosystems can be removed

Debris smothers the reef
Large amounts of sediment can simply cover and kill coral. The only way coral can rid themselves of sediment is to bind it in mucus and let water flow wash sheets of it away. Too much sediment buries the live coral polyps and kills them.

Increased nutrients encourages algal growth
Sediment usually brings extra fertilizer to the reef ecosystem. Weedy algae take best advantage of sudden increases in nutrients faster than coral. Algae can bloom, overgrow and dominate a reef if enough nutrients are added to the ecosystem.

Water clarity is reduced
Sediment clouds the water, decreases water clarity and interferes with the ability of zooxanthellae algae to photosynthesize. If zooxanthellae, which live in symbiosis with coral, are unable to photosynthesize they may be expelled from the coral. Corals can survive for only short periods of time without functioning zooxanthellae.

Removal of vital ecosystems
Many ecosystems are important for the health of coral reefs. Mangroves and seagrass trap sediment and provide habitat for young reef fish to grow (Little fish). Removing these ecosystems during construction can release previously trapped sediment and removes the ability to trap debris created during construction.

 Can tourism harm coral reefs? Increased Nutrients

Worldwide, coral reef tourism generates about US$9.6 billion each year. Tourism is also the greatest source of foreign income for some tropical nations like Fiji and the Maldives. This income is also sustainable - provided the reefs remain healthy.

Ironically, construction of tourist facilities can harm reefs, but with careful planning, tourist facilities can greatly enhance a coral reef experience, and provide income to well protected reef areas.

Tourists can also damage reefs directly through trampling, clumsy SCUBA diving, resuspension of sediment, and overfishing.

 Sustainability and coastal development Debris

Too much disturbance reduces ecosystem diversity and reduces diversity in nearby ecosystems. Construction can create disturbance that damages mangroves or seagrass. Damage to these ecosystems can also harm the health of coral reefs.

 References

CDNN. (2005, August 15). Overdevelopment, pollution threaten billion-dollar Caribbean dive tourism industry. CDNN global news network. Retrieved 1 August 2008 from http://www.cdnn.info/news/industry/i050821.html

Kannan, L. & Thangaradjou, T. (2008, January 10). Seagrasses. United Nations University. PDF retrieved 1 August 2008 from http://ocw.unu.edu/international-network-on-water-environment-and-health/unu-inweh-course-1-mangroves/Seagrasses.pdf

Kelley, R. et al. (2006, December 19). Nutrients, catchments and reefs – a guide to nutrients in the tropical landscape. Catchment to Reef Program. PDF retrieved 22 August 2008 from http://www.catchmenttoreef.com.au/Products_files/NCR.pdf

The Coral Reef Alliance. (2005). Coastal development: Planning for a sustainable reef. The Coral Reef Alliance (CORAL). Retrieved 1 August 2008 from http://www.coralreefalliance.org/index.php?option=com_content&task=view&id=57&Itemid=67

The Nature Conservancy. (2006, November). Coral Triangle Center. The Nature Conservancy. Retrieved 1 August 2008 from http://www.coraltrianglecenter.org/

Tourism Queensland. (2003, November 10). Dive tourism. Tourism Queensland. PDF retrieved 1 August 2008 from http://www.tq.com.au/fms/tq_corporate/research/fact_sheets/dive_tourism.pdf

Tsui, B. (2007, June 24). Saving Coral Reefs Becomes a Tourism Priority. The New York Times. Retrieved 1 August 2008 from http://travel.nytimes.com/2007/06/24/travel/24headsup.html?ref=travel

Wikipedia. (2008, June 28). Economy of Fiji. Wikipedia. Retrieved 1 August 2008 from http://en.wikipedia.org/wiki/Economy_of_Fiji

World Resources Staff. (1998). Coral reefs: Assessing the threat. World Resources Institute. Retrieved 1 August 2008 from http://earthtrends.wri.org/text/coastal-marine/feature-12.html

World Resources Staff. (2007, October). Economic valuation of coral reefs. World Resources Institute. PDF retrieved 1 August 2008 from http://pdf.wri.org/coral_reefs_methodology-10-2007.pdf

WWF. (2008, February 28). Coastal development problems: Tourism. World Wildlife Fund. Retrieved 1 August 2008 from http://www.panda.org/about_wwf/what_we_do/marine/problems/tourism/tourism_pressure/index.cfm

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