Coral reefs are the only ecosystem that is strongly defined by a geological
component - most definitions require that the biological community produce
s its own build-up of calcium carbonate. In terms of "reef-building," the g
eological record reveals that coral reefs have flourished over the past few
million years, particularly during interglacial periods. Based on our obse
rvations of modern-day reefs, which are limited to the past few centuries,
we tend to link "coral reef health" to carbonate production; however, reef
ecosystems face future global-scale environmental changes that may decrease
their reef-building capacity. In contrast to past discussions of the facto
rs which determine reef-building potential by a coral reef community, the e
ssential question that arises from this review is: How important is reef bu
ilding to a coral reef community?