#Status of Coral Reefs 2002 - International Coral Reef Action Network

1. CORAL BLEACHING AND MORTALITY –
THE 1998 EVENT 4 YEARS LATER
AND BLEACHING TO 2002
CLIVE WILKINSON
The two distinct themes in this Chapter are:
• how well have reefs recovered after the 1997-98 mass bleaching event and what
lessons we have learned; and
• what has happened in coral bleaching since 1998 and where, and are there any
patterns?
The major coral bleaching and mortality event of late 1997 and 1998 was by far the worst
on record and also the most widespread. Reefs in the 3 Oceans were affected with severe
bleaching stretching from the Arabian/Persian Gulf through the northern and central
Indian Ocean, parts of Southeast Asia and the Great Barrier Reef of Australia, the far west
Pacific, throughout the Caribbean and as far as Brazil in the Atlantic Ocean. By far the
most severe bleaching in mortality terms was on reefs in the Indian Ocean north of
Latitude 10°S; in southeast and east Asia; and around Palau in the West Pacific.
The levels of bleaching and mortality have been reported in the Status of Coral Reefs of
the World reports in 1998 and 2000 and are also summarised in the Chapters following.
The critical point for discussion in this chapter is: has there been coral recovery, and if so
by how much; and if not, are there any reasons for this lack of recovery.
SUMMARY OF RECOVERY AFTER THE 1998 BLEACHING
Middle East
Bleaching damage in the Red Sea in 1998 was relatively minor, however there were
devastating bleaching impacts in the Arabian/Persian Gulf in 1996 and 1998 and virtually
all shallow water corals on the Arabian side were destroyed. Recovery of these reefs will
take many decades because breeding stocks have been lost and natural recruitment was
already variable and low prior to 1998. There is some recovery of reefs damaged along the
coast of Iran after moderate to slight losses in 1998.
Eastern Africa and Oman
Recovery of damaged reefs in Kenya and Tanzania has been poor to moderate, and very
patchy. Reefs that previously had high coral diversity and cover have recovered to less
than one quarter of their previous coral cover. Degraded reefs with low coral cover outside
MPAs have generally recovered half to all of the pre-bleaching cover. The highest coral
recruitment has been on protected reefs with reasonably healthy stocks of parent corals
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