Coastal Environments and Global Change

16Coral Reefs

Paul Kench

School of Environment, The University of Auckland, Auckland, New Zealand

16.1 Coral reefs in context

Distributed throughout the tropical oceans, coral reefs extend over approximately 300,000 km² of the Earth’s surface. While relatively modest in spatial extent compared with other coastal systems considered in this book, coral reefs are considered among the most valuable ecosystems on Earth. Their ecological value is well recognized as they are zones of high biological diversity and habitat to 25% of known marine species. Furthermore, it is estimated that coral reefs provide goods and services in the order of $US375 billion to coastal communities on an annual basis (Best and Bornbusch, 2005). Less well recognized is the ‘geomorphic value’ provided by reefs as a consequence of the ecosystem services they provide. For example, coral reefs provide the physical foundation of a number of mid-ocean atoll nations (e.g. Kiribati, Tuvalu, Maldives and Marshall Islands). As well as providing habitat, coral reef structure regulates oceanographic processes that control reef and lagoon circulation, and wave energy levels that impact coastlines.

Coral reefs are unique coastal environments as they represent a delicate balance between ecological processes (organisms) that produce calcium carbonate (CaCO₃) material, and ecological and physical processes that act to breakdown and redistribute CaCO₃ to control the development and morphology of reef landforms. Consequently, without ...