Trends in the health of coral reefs worldwide were examined by surveyi
ng the literature for quantitative studies of coral abundance that wer
e at least four years long and contained data on variance among sample
s. Of the 65 examples in which sufficient data exist to make a judgmen
t, coral cover did not decline in 29%, with fewer declines in the Indo
-Pacific than in the W. Atlantic. Coral cover declined and recovered i
n 29% (all in the Indo-Pacific) and declined but did not recover in 42
% of the examples (16% in the Indo-Pacific and 26% in the W. Atlantic)
. Thus, coral assemblages were relatively stable over ecological time
scales in 58% of the examples surveyed. However, the W. Atlantic regio
n was more unstable than the Indo-Pacific; declines without subsequent
recovery occurred in 57% of W. Atlantic examples but in only 29% of t
hose in the Indo-Pacific. The principal reason corals recovered in som
e local sites but not in others seems to be related to the type of dis
turbance that caused the decline. Coral cover recovered after 69% of t
he acute, short-term disturbances but after only 27% of the chronic, l
ong-term ones.