Coral Reef NOAA
May 25, 2016  

Coastal Protection

Healthy coral reefs have rough surfaces and complex structures that dissipate much of the force of incoming waves; this buffers shorelines from currents, waves, and storms, helping to prevent loss of life, property damage, and erosion. [a] Up to 90 percent of the energy from wind-generated waves is absorbed by reefs, based on the physical and ecological characteristics of the reef and the abundance of the adjacent seagrass and mangrove ecosystems. [b] In fact, coastlines protected by reefs are more stable, in terms of erosion, than those without. [c] Reefs are also a source of sand in natural beach replenishment. [d]

Of the $29.8 billion global net benefit of coral reefs, $9.0 billion is accounted for by the coastal protection coral reefs provide. [e] In the US alone, coastal storms account for 71 percent of recent annual disaster losses. Each event costs roughly $500 million, and while not all of these events occur in areas that would naturally contain reefs, healthy reefs could reduce the cost in those regions that do. [f] In fact, each meter of reef protects an estimated $47,000 of property value. In Florida, the absence of coral reefs would cause parts of the state to be submerged. In Belize, coastal protection afforded by reefs and mangroves provide an estimated $231 to $347 million in avoided damages per year. By comparison, Belize's gross domestic product in 2007 was $1.3 billion. [g]

Losing the natural reef barrier would have significant physical and economic effects on coastal communities as well as the millions of people who live in coastal areas near coral reefs. Therefore, the health of sensitive coral reef ecosystems depends partly on sustainable coastal development practices along the very same coastlines the reefs themselves protect. A study conducted in 1999 suggests that a 1% loss in coastal ecosystems leads to 1% loss in the coastal protection function, and this in turn to a loss of 1% of the value of the coastline. [h]

Sadly, the value of reefs as a means of coastal protection is more easily measured in economic terms when reefs have to be replaced by manmade structures due to loss of the natural reef—replacement costs are often used as a proxy for the value of the ecosystem service of coastal protection. In the Maldives, for example, an artificial breakwater cost about $12 million to build as a replacement for naturally occurring reef that was lost. [i] On Tarawa Atoll in Kiribati, coastal defences costing $90,720 had to be built to prevent coastal erosion. Reef replacement costs, following years of coral mining in Sri Lanka, varied between $246,000 and $836,000 km-1. [j]

*Unless otherwise noted, all monetary values presented are in US Dollars.