Coral reefs provide approximately $30 billion dollars’ worth of goods and services to human beings each year (Kittinger et al. 2012). Although coral reefs only cover 0.1-0.5% of the ocean floor, approximately 1/3 of the world’s fishes inhabit these ecosystems. In fact, millions of people around the globe rely on coral reefs for their main source of protein. Since coral reefs are aesthetically beautiful ecosystems, many recreational and tourisms related activities such as diving, and snorkeling occur on coral reefs.
In 1985, approximately 1.1 million tourists visited the Great Barrier Reef in Australia and this number increased to over 10 million in 1995. By 1997, the tourism industry on the Great Barrier Reef in Australia was valued at $700 million US dollars. A study conducted in 2000 found that the dive tourism industry in the Caribbean was valued at over $2 billion dollars (Spalding et al. 2001; Burke et al. 2004). Coral reefs also provide other employment opportunities for people working in hotels, recreational fishing operations and other sectors of the tourism industry (Spalding et al.2001).
Coral reefs protect coastlines from the energy produced by currents, wave action and storm events. In fact, a recent study found that coral reefs reduce up to 97% of the energy produced by waves (Ferrario et al. 2014). By buffering the shoreline from these stressors, coral reefs prevent shoreline erosion and without this protection, humans must invest in costly alternatives to prevent coastal erosion.
For example, in 2006, coral destruction cost Indonesia approximately $ 820-1,000,000 dollars for each km of shoreline and in the Maldives, $12,000,000 was spent to create an artificial structure that would replace the buffering services provided naturally by coral reefs (Moberg and Folke 1999). Coral reefs also provide aesthetic, cultural, religious and spiritual values, services, practices and traditions for coastal people in tropical environments. In fact, the health and well-being of people who live in tropical, coastal environments rely heavily upon the cultural services that coral reefs provide (Kittinger et al. 2012).
Ecological good and services
Coral reefs provide numerous ecological goods and services that are required for an ecosystem to function properly. Coral reefs serve as important spawning and nursery sites and create habitats for a variety of different coral reef organisms. They regulate the concentration of calcium in the world’s oceans and their mucus may help support the pelagic food web. In addition, coral reefs serve as corridors through which organisms can migrate between different ecosystems such as mangrove lagoons and seagrass beds. This migration allows for the transfer of energy between different ecosystems (Moberg and Folke 1999).
A Summary of Threats to Coral Reefs
Despite all the goods and services provided by coral reefs, within the past 30 years, a combination of human and natural stressors have led to the degradation of coral reefs around the world (Souter and Linden 2000; Spalding et al. 2001; Gardner et al. 2003; Bellwood et al. 2004;Weil 2004; Hughes et al. 2010; Morais et al. 2018). In the Caribbean region alone, absolute hard coral cover declined from approximately 50% in 1977 to 10% in 2001 (Gardner et al. 2003). In extreme cases, coral reefs have been known to disappear entirely and are replaced by organisms that do not provide the same ecological and economical services (Hughes 1994; Lapointe et al. 2007; Edmunds and Elahi 2007; Bruno et al. 2009; Filip 2010; McClenachan et al. 2017).
This global decline in coral cover has been attributed to the combined effects of pollution, sedimentation, overfishing, climate change and disease on coral reefs (Souter and Linden 2000; Williams and Bunkley-Williams 2000; Aronson and Precht 2001; Spalding et al. 2001; Sutherland et al. 2004; Mora 2007; Croquer and Weil 2009a; ICRI/UNEP-WCMC 2010; Jackson et al. 2014; Harborne et al. 2016; Pendleton et al. 2016).
1. Aronson, R.B., Precht, W.F. (2001). White-band disease and the changing face of Caribbean coral reefs. Hydrobiologia, 460: 25-38.
2. Bellwood, D.R., Hughes, T.P., Folke, C., Nystrom, M. (2004). Confronting the coral reef crisis. Nature, 429: 827- 833.
3. Bruno,J.F., Sweatman, H., Precht, W.F., Selig, E.R., Schutte, V.G.W. (2009). Assessing evidence of phase shifts from coral to macroalgal dominance on coral reefs. Ecology, 90(6): 1478-1484.
4. Croquer, A., Weil, E. (2009a). Changes in Caribbean coral disease prevalence after the 2005 bleaching event.Dis Aquast Org, 87: 33-43.
5. Edmunds, P.J., Elahi, R. (2007). The demographics of a 15-year decline in cover of the Caribbean reef coral Montastraea annularis. Ecological Monographs, 77(1): 3-18.
6. Filip, L.A. (2010). Habitat complexity in coral reefs: patterns of degradation and consequences for biodiversity.
7. Gardner, T. A., Côté, I. M., Gill, J. A., Grant, A., & Watkinson, A. R. (2003). Long-term region-wide declines in Caribbean corals. Science, 301(5635), 958-960.
8. Harborne, A.R., Rogers, A., Bozec, Y-M., Mumby, P.J. (2012). Multiple stressors and the functioning of coral reefs. Annu. Rev. Mar. Sci., 9: 5.1-5.24.
9. Hughes, T.P. (1994). Catastrophes, phase shifts, and large-scale degradation of a Caribbean coral reef. Science, 265: 1547-1551.
10. ICRI/UNEP-WCMC (2010). Disease in Tropical Coral Reef Ecosystems: ICRI Key Messages on Coral Disease, 1-13.
11. Jackson JBC, Donovan MK, Cramer KL, Lam VV (editors). (2014) Status and Trends of Caribbean Coral Reefs:1970-2012. Global Coral Reef Monitoring Network, IUCN, Gland, Switzerland.
12. Lapointe, B.E., Littler, M.M., Littler, D.S. (1997). Macroalgal overgrowth of fringing coral reefs at Discovery Bay, Jamaica: bottom-up versus top-down control. Proc 8th Int Coral Reef Sym, I:927-932.
13. McClenachan, L., O’Connor, G.O., Neal, B.P., Pandolfi, J.M., Jackson, J.B.C. (2017). Ghost reefs: nautical charts document large spatial scale of coral reef loss over 240 years. Sci. Adv., 3:1-7.
14. Mora, C. (2008). A clear human footprint in the coral reefs of the Caribbean. Proc. R. Soc. B, 275: 767-773.