Unprecedented depletion of corals threatens marine ecosystems in the tropics
THE us National Oceanic and Atmospheric Administration (NOAA) has come
out with alarming findings about corals,
tiny marine organisms which secrete calcareous shells that combine to form
coral reefs. Record-breaking depletion
of corals and extremely warm waters
occurred throughout the tropics during
the first half of 1998, the NOAA
announced on October 16.
Coral reefs - the rainforests of the
sea - are some of the oldest and most
biologically diverse ecosystems on the
Earth. Important assets to local and
national economies, corals produce
fisheries for food, materials for new
medicines, and income from tourism
and recreation. They also protect coastal
communities from storms. "Coral
bleaching is a sign that reefs are under
severe stress and may be seriously damaged," said NOAA administrator D James
Baker. Coral bleaching results from a
number of factors including pollution,
sedimentation or changes in salinity.
"With 1998 named the Year of the
Ocean, it is appropriate that we focus
our attention on these extremely important and fragile coral reef ecosystems,"
Baker added.
Corals thrive as long as temperatures remain at or below certain temperatures for a given site. An slight
increase above the usual maximum
temperatures can be deadly for them.
While many corals normally recover from short bleaching events, long-term
or frequent bleaching may severely weaken the corals leaving them more
vulnerable to disease, damage or death.
Data from NOAA'S satellites show
that during the first half of 1998, more
ocean area in the tropics experienced
exceptionally high sea surface temperatures, or "hot spots", than observed in
any full year since 1982. Approximately
50 countries have reported coral bleaching since 1997. During the El Nifio of
1982-83, large areas of coral reef around
the world were severely damaged by high water temperatures associated with
coral bleaching. Before this, the annual
record for high ocean temperature
events was in 1988, which also followed
an El Nino, year.
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