Post on 27-Jul-2020
http://ourworld.compuserve.com/homepages/ mccarty_and_peters/coral/C-intro.htm
Coral Reefs
http://tools.coralreef.org/content/ objects/view.acs?object_id=545
Importance of Coral Reefs
• 0.2% of world’s oceans • Habitat for 1/3 of marine fishes • Habitat for tens of thousands of
other animals • The rainforests of the oceans
Importance of Coral Reefs
• PROTECTION TO COASTLINES • ECONOMIC RESOURCES • BIODIVERSITY • NATURAL BEAUTY
Importance of Coral Reefs
• PROTECTION TO COASTLINES
– absorb energy of ocean waves
– reduce erosion of shoreline
– storm damage
– flooding
Importance of Coral Reefs
• ECONOMIC RESOURCES – Fisheries for food – Fisheries for jobs – Tourism – Building materials – Aquarium trade
Importance of Coral Reefs
• BIODIVERSITY
– The rainforests of the sea
– Genetic diversity
– Pharmaceuticals
Importance of Coral Reefs
• NATURAL BEAUTY
http://sustainableseas.noaa.gov/missions/ florida2/background/coralspawning.html
$375 billion in environmental goods and services
Reefs at Risk 1998 (http://www.wri.org/powerpoints/reefswww/sld011.htm
Caribbean reef values (annual net benefits in 2000)
• Fisheries: $310 million
• Dive tourism: $2.1 billion
• Shoreline protection: $0.7-2.2 billion
Total: $4.1-4.6 billion
REEFS WORLDWIDE ARE THREATENED
• 11% of reefs have been lost
• 16% of reefs severely damaged
• ~60% of studied reefs threatened by human activities
• No pristine reefs left
CARIBBEAN REEFS DECLINING
• 1970s: ~50% coral cover
• Present: ~10% coral cover
• =80% reduction in coral cover over last 30 years
Gardner et al. 2003 Science 301: 958-960
Threats to coral and coral reefs:
1) Natural
2) Anthropogenic – of human origin
Natural disturbances that affect corals and coral reefs?
• Hurricanes
• Tsunamis
• Volcanoes
• Earthquakes
• Predators & competitors
• Bleaching
• Pathogens
Hurricanes
• Physical damage
http://www.nhc.noaa.gov/ 1989hugo.html
• Destruction of other ecosystems upon which coral reefs depend
• Freshwater poisoning
• Smothering
Tsunamis
• Physical damage
• Possible disruption of reproduction and recruitment
• Erosion
Volcanoes
• Depends upon where volcano occurs
http://volcano.und.nodak.edu/vwdocs/ current_volcs/montserrat/montserrat.html
• smothering and sedimentation
• Heat
Earthquakes
• Little direct impact
- coastal landslides
• Indirect impacts
- triggers tsunamis
Predators • crown of thorns
starfish • snails • parrotfish • butterflyfish
http://www.aims.gov.au/pages/reflib/ cot-starfish/pages/cot-q07.html
http://www.sanctuaries.nos.noaa.gov/pgallery/pgflower/living/fg_living.html
Competitors
• algae
http://catbert.er.usgs.gov/african_dust/algae.html
• Loss of zooxanthellae
• causes – higher than usual
ocean temperature
– sharp changes in salinity
– heavy UV light exposure
http://ourworld.compuserve.com/homepages/ mccarty_and_peters/coral/Bleach.htm
http://orbit-net.nesdis.noaa.gov/orad/coral_bleaching_index.html
Pathogens
• Diseases on the rise – new pathogens
(8+) – land pathogens
(Aspergillus) – occurring at all
depths – More susceptible
when stressed http://ourworld.compuserve.com/ homepages/mccarty_and_peters/ coral/Bbd.htm
Threats to coral and coral reefs:
1) Natural
2) Anthropogenic – of human origin
Anthropogenic threats to coral reefs:
• Overfishing
• Development
• Mining and dredging
• Recreation
Overfishing
• Ecological imbalance
http://tools.coralreef.org/content/objects/view.acs?object_id=545
http://www.photolib.noaa.gov/reef/reef2570.htm
Overfishing
• Ecological imbalance
http://catbert.er.usgs.gov/african_dust/events.html
http://oceanworld.tamu.edu/students/coral/coral5.htm http://www.wri.org/indictrs/rrcyanid.htm
Overfishing
• Destructive fishing practices
Development
• Sediment smothering
• Freshwater input
• Pollutants & nutrients (sewage, pesticides, fertilizer, heavy metals, pathogens)
http://www.wcmc.org.uk/marine/data/coral_mangrove/coral.danger.html
http://ourworld.compuserve.com/homepages/mccarty_and_peters/coral/c-intro.htm
Development
Development
http://www.sanctuaries.nos.noaa.gov/scied/science/habitat/influences.html
Mining for construction materials and dredging
• Destruction of reef structure
• stirs up sediment
Recreation
Anchors, boats, flippers, hands, feet • Kill animal tissue • Skeleton breakage
http://www.sanctuaries.nos.noaa.gov/scied/science/habitat/influences.html
• interaction of natural changes & human activity
• multiple insults
Synergistic effects
Global climate change
• Reduced reef building
• Increase in frequency and intensity of hurricanes
• Increases in bleaching
• Increased in disease
CORAL DOMINATED
ALGAL DOMINATED
Synergistic effects
OVERFISHING
HURRICANE ALLEN 1980
ACROPORA DIE-OFF 1980S
DIADEMA DIE-OFF 1983
JAMAICA
MORE ALGAE
NO GRAZERS
LESS CORAL
PHYSICAL DAMAGE
ALGAL DOMINATED
SYNERGISTIC EFFECTS
JAMAICA
PROTECTION SINCE 1961
ACROPORA DIE-OFF 1980S
DIADEMA DIE-OFF 1983
HURRICANE HUGO 1989
HURRICANES MARILYN/LUIS 1995
BUCK ISLAND, ST. CROIX
PROTECTION
LITTLE OVERFISHING
DISEASE
PHYSICAL DAMAGE
CORAL DOMINATED
BUCK ISLAND, ST. CROIX