Download What are corals? - IFES Symposium on Climate Change

Impacts of Climate Change on the marine
environment –
a case study of the Caribbean
IFES Symposium on Climate Change
October 20-25, 2008
Climate change and the marine environment
• Over the last 200 years, human induced emissions of greenhouse gases have also
contributed to global climate change
• Many marine ecosystems are responding both physically and biologically to changes
in regional climate
• This is caused predominately by the
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warming of air,
the increase in sea surface temperature (SST)
modification of currents,
precipitation regimes
wind patterns.
Impact on marine ecosystems and wildlife
• Marine Ecosystems
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Mangroves
Seagrass beds
Coral Reefs
Open Ocean
• Marine Wildlife
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Marine mammals, reptiles and amphibians
Fishes stocks
Marine birds
Plankton
Coral Reefs Under Threat
• Over a third of the world's coral species are at elevated risk of extinction.
• Reefs of the Western Atlantic have generally decreased in living corals since the
1970’s
• Reefs of the Great Barrier Reef were resilient until 1996, they are now beginning to
struggle
• The degradation of many reefs are due to combination of the global stresses of
climate change
• Also regional and local stressors including runoff from agriculture, other land-based
sources of pollution, over-fishing, and habitat destruction associated with coastal
development.
What are corals?
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The corals that form reefs are “hard corals” with skeletons of calcium carbonate.
These “reef-building” corals are usually composed of
• many polyps (colonial)
• microscopic plants (zooxanthellae) in their tissues which provide some additional food for the coral
by photosynthesis
• need light and so grow close to the surface of the sea.
• reef-builders require water temperatures of 20-28°C and so are located almost entirely between
30°N and 30°S.
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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Increased sea surface temperature
Sea level rise as a result of large melting of the ice-caps
Increasing concentration of CO2 in seawater.
Altered circulation patterns
Increased frequency of severe weather events
Why do coral bleach?
• Corals go pale or white as a result of stress
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Prolonged elevated sea surface temperatures.
High levels of UV light
Low light conditions
High turbidity, sedimentation
Disease
Variable salinity
Pollution
Mass Bleaching –
a recent phenomenon
• 1997-1998
– Mass mortality of corals
– 16% of worlds reef seriously damaged and on 40% of these recovered
• 2002
– Great Barrier Reef and SW Pacific
• 2005/2006
– Caribbean and Western Atlantic
The Wider Caribbean
Thermal Stress
(Degree heating weeks map – NOAA)
Assessment of Bleaching in Jamaica
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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 the 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.
Bleached coral populations at various sites around Jamaica
Bleaching and subsequent mortality of corals in
some Caribbean Countries
Bleached corals
Coral Diseases
• September 2006 - black band and white plague disease noted
in the Port Royal Cays
• Affected mainly the massive corals Siderastrea, Montastraea
and Diploria species
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.
Hurricane tracks 2000-2006
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
Implication for coral reef health in the future
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More frequent bleaching events
Increased susceptibility to coral diseases
Shift in community structure
Reduced ability to withstand anthropogenic impacts
Further damage as a result of storm events
Can coral adapt to climate change?
• Adaptation
– Genetic variability, resistant genotypes
• Acclimatization
– Biochemical or physiological
• Range shift
– Expand to the sub-tropics
What can be done?
• Coral reef restoration
– Artificial reefs
– Coral gardening
• Research
– Species resistant to temperature increases and diseases
– Stress history of specific species
• Reduced localized stressors
– Less stressed reefs recover better
– Marine protected areas
• Changes is resource use
– Fisheries and tourism
International Year of the Reef:
IYOR 2008
• Resolution was approved by the ICRI members at the ICRI General Meeting
held in Cozumel, Mexico (22-23 October 2006)
• Goals
– Strengthening awareness about the ecological, economic, social and cultural
value of, and critical threats to, coral reefs and associated ecosystems; and
– Generating urgent action at all levels to develop and implement effective
management strategies for conservation and sustainable use of these
ecosystems.
Call to Action
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Cut CO2 emissions by lowering our carbon footprint and ask our policymakers to commit to low carbon
economic growth.
Eliminate open access fisheries in coral reef ecosystems.
Protect coral reef herbivores, including parrotfish.
Establish and strictly enforce networks of Marine Protected Areas that include No-Take Areas.
Effectively manage the waters in between Marine Protected Areas.
Maintain connectivity between coral reefs and associated habitats.
Report regularly and publicly on the health of local coral reefs.
Recognize the links between what we do on land and how it affects the ocean.
Bring local actors together to develop a shared vision of healthy reefs and a road map for getting there.
Work for change with management to produce desired outcomes.
Thank you.