Transcript Coral Bleaching – a consequence of Climate Change in the

Impacts of Climate Change on Coral reefs in the Caribbean
Mrs. Marcia Creary
Impacts of Climate Change on
coral reefs in the Caribbean
Climate Change: Impacts on the Caribbean
June 15-17, 2007
Faculty of Social Sciences, UWI &
Caribbean Community Climate Change Centre
Marcia M. Creary & Loureene Jones
Caribbean Coastal Data Centre
Centre for Marine Sciences
University of the West Indies
What are corals?
• The corals that form reefs are “hard corals” with
skeletons of calcium carbonate.
• These “reef-building” corals are usually composed of
many polyps (colonial) and have microscopic plants
(zooxanthellae) in their tissues which provide some
additional food for the coral by photosynthesis – thus
reef-building corals need light and so grow close to
the surface of the sea.
What are coral reefs?
• Coral reefs are large structures composed
mainly of dead coral skeletons built up over
thousands of years.
• The reef maintains itself by the continued
growth of living corals
Climate change factors that
affect coral reefs
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Sea level rise
Increased sea surface temperature
Reduced calcification rates
Altered circulation patterns
Increased frequency of sever weather
events
Why do coral bleach?
• Corals go pale or white as a result of
stress
– Prolonged elevated sea surface
temperatures.
– High levels of UV light
– Low light conditions
– High turbidity, sedimentation
– Disease
– Variable salinity
– Pollution
What is
coral
bleaching?
Mass Bleaching –
a recent phenomenon
• 1997-1998
– Mass mortality of corals
– 16% of worlds reef destroyed
• 2002
– Great Barrier Reef and SW Pacific
• 2005
– Caribbean and Western Atlantic
Status of Caribbean Coral Reefs after Bleaching and
Hurricanes in 2005 and 2006.
Special Report by GCRMN
Global trends in the extent and
severity of mass bleaching.
(IUCN)
Bleaching study in
Jamaica
• August - October 2005 Jamaica and other Caribbean
nations experienced prolonged high sea surface
temperatures
• Jamaica experienced 5-6 weeks of exposure to higher
than normal temperatures which resulted in widespread
bleaching
• Funding was received from Reef Check International
though NOAA to document the event.
• November 2005 to May 2006 , Reef Check surveys with
an additional bleaching component were conducted.
• Sites located in Negril, Discovery Bay, Portland, Port
Royal and Portland Bight Protected Area were assessed
twice. First to determine the extent of bleaching and
second to assess level of recovery.
Observed bleaching
• Bleaching was first noted on the north coast of
the island late August to early September and
later manifested on the south coast in late
September to early October.
• The effects of the bleaching episode were more
pronounced on the south coast than on the
north.
Thermal Stress
(Degree heating weeks map – NOAA)
Number of weeks of exposure to higher than normal temperatures.
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Bleaching was observed at most sites.
25
20
Sites exhibited varying
degrees of bleaching
from10 % to 95%.
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Sites
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Bleached percentage
Bleached coral populations at various
sites around Jamaica
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HC
On the resurvey, up to 50%
of the bleached corals had
recovered.
Bleached corals
Coral species bleached
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Montastrea annularis
Montastrea faveolata
Montastrea cavernosa
Siderastrea siderea
Diploria strigosa
Agaricia spp.
Millepora complanata
Porites porites
Hurricanes
• Major hurricanes that have impacted
Jamaica’s reefs include Hurricane Allen in
1980, Hurricane Gilbert in 1988 and
Hurricane Ivan in 2004.
• Hurricane Ivan caused visible damage to
coastal areas. Variable levels of damage
were noted on the north and south coasts.
• In 2004 and 2005 (Dennis, Emily and
Wilma) hurricanes passed south of
Jamaica, as such reefs on the south coast
have been hardest hit.
Other threats to Caribbean
Reefs
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Coastal development
Inland activities
Over-fishing
Destructive fishing
practices
• Waste disposal
• Ship-based activities
• Physical damage
Can coral adapt to
climate change?
• Adaptation
– Genetic variability
• Acclimatization
– Biochemical or physiological
• Range shift
– Expand to the sub-tropics
What does this mean for the
tourism and insurance industries?
• Shoreline protection
• Sand replenishment
• Water sport activities
– Diving
– Snorkeling
– Swimming
• Food source
• Aesthetic, biodiversity
Thank you.