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global bleaching event was recorded in 1998. Since then, sev-
eral regional and local events occured, such as in the Carib-
bean in 2005 (Wilkinson, C. and Souter, D., 2008). Bleaching
affects the majority of the tropical reefs around the World,
with a large proportion dying. The rate of recovery is different
from region to region, with healthy reefs (i.e. reefs not or only
marginally stressed by other pressures) generally recovering
and re-colonising quicker than reefs in poor condition. Some
of the latter did not recover at all. The dead coral skeletons are
broken down by wave activity and storms into coral rubble,
leading to a change in the whole ecosystem from a rich and
diverse coral reef into a much more impoverished community
dominated by algae.
Figure 10. The impacts of coral reefs from rising sea temperatures.
When coral reefs become heat-exposed they die, leaving the
white dead coral, also known as bleaching. With even moderate pollution, the coral are easily overgrown with algae, or broken
down by wave activity or storms, leaving only ‘coral rubble’ on the ocean bed (Donner
et al
., 2005).