KOROR STATE GOVERNMENT MARINE TOUR GUIDE ... - C3

Coral Bleaching Event in Palau
The first signs of bleaching in Palau were noticed in late June of 1998 and by September
bleaching was obvious and extensive. A study by Bruno et al., in November 1998 found
slightly more than 50% of surface cover of hard corals to be bleached. Only 37% of hard
corals were not at all bleached and most soft corals were completely bleached. A
detailed study by PCS in 1999 estimated that about one-third of all hard corals and a
higher percentage of soft corals had died as a result of the bleaching. The damage was
found to vary greatly by area, habitat and type of coral. Some species appear to have
lost more than 99% of their cover. The outer barrier reefs, where most of the scubadiving
takes place, appeared to have been hit harder than the lagoon area, where most
snorkeling takes place. PCS found that about 60% of 30 surveyed sites had lost more
than half of their live hard coral cover.
What can be done about climate change?
The ultimate solution to protect coral reefs would be to target the source of global
climate change, i.e. a reduction of greenhouse gases emissions through reduced fossil
fuel burning and increased reforestation. The extent and rate of such changes are
governed by complex political and socio-economic drivers and are unpredictable.
Continued research into the causes and consequences of global climate change is
important. Accurate predictions of the geographic patterns and rates of change, and the
ways to respond to them must be available to governments and communities.
Information Sources:
Coral Bleaching and global climate change. Current State of Knowledge, January 2002.
CRC Reef Research Centre, Australia.
Dive Tourism in Palau: Resource Use, Value and Management. Tom Graham, PCS,
June 2001.
3.6.3 Other Threats
An estimated 30% of the coral reefs worldwide are already severely damaged, and close
to 60% may be lost by 2030. There are no pristine reefs left. Until recently, the direct and
indirect effects of over-fishing and pollution from agriculture and land development have
been the major drivers of massive and accelerating decreases in abundance of coral
reef species, causing widespread changes in reef ecosystems over the past two
centuries. With increased human populations and improved storage and transport
systems, the scale of human impacts on reefs has grown exponentially. For example,
markets for fishes and other natural resources have become global, supplying demand
for reef resources far removed from their tropical sources. On many reefs, reduced
stocks of herbivorous (vegetarian) fishes and added nutrients from land-based activities
have caused ecological shifts, from the original dominance by corals to an abundance of
fleshy seaweed. These changes to reefs, which can often be managed successfully at a
local scale, are compounded by the more recent, superimposed impacts of global
climate change. Future changes in ocean chemistry due to higher atmospheric carbon
dioxide may cause weakening of coral skeletons and reduce the accretion of reefs,
especially at higher latitudes.
Information Source: Climate Change, Human Impacts, and the Resilience of Coral
Reefs T. P. Hughes et al. SCIENCE VOL 301 15 AUGUST 2003
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