Coral Reefs

http://tools.coralreef.org/content/ objects/view.acs?object_id=545

http://ourworld.compuserve.com/homepages/ mccarty_and_peters/coral/C­intro.htm

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: $0.7­2.2

billion

Total: $4.1­4.6 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: 958­960

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

•Smothering

http://www.nhc.noaa.gov/ 1989hugo.html

•Freshwater poisoning

•Destruction of other ecosystems upon

which coral reefs depend

Tsunamis

• Physical damage

•Erosion

•Possible disruption of  reproduction and recruitment

Volcanoes

• Depends upon  where volcano  occurs

•Heat

•smothering and

sedimentation

http://volcano.und.nodak.edu/vwdocs/ current_volcs/montserrat/montserrat.html

Earthquakes

• Little direct impact

­triggers tsunamis

­coastal landslides

•Indirect impacts

Predators

• crown of thorns starfish  • snails • parrotfish • butterflyfish

http://www.aims.gov.au/pages/reflib/ cot­starfish/pages/cot­q07.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

http://ourworld.compuserve.com/homepages/ mccarty_and_peters/coral/Bleach.htm

– heavy UV light

exposure

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://www.photolib.noaa.go v/reef/reef2570.htm

http://tools.coralreef.org/content/objects/view.acs?object_id=545

Overfishing

• Ecological imbalance

http://catbert.er.usgs.gov/african_dust/events.html

Overfishing

• Destructive fishing practices

http://www.wri.org/indictrs/rrcyanid.htm

http://oceanworld.tamu.edu/stud ents/coral/coral5.htm

Development

smothering

• Sediment fi • Freshwater input • Pollutants & nutrients         (sewage,  pesticides, fertilizer, heavy metals,  pathogens)

Development

http://www.wcmc.org.uk/marine/data/ coral_mangrove/coral.danger.html

http://ourworld.compuserve.com/homepag es/mccarty_and_peters/coral/c­intro.htm

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/scie nce/habitat/influences.html

Synergistic effects

• interaction of natural changes &

human activity • multiple insults

Global climate change

• Reduced reef building • Increase in frequency and

intensity of hurricanes • Increases in bleaching • Increased in disease

Synergistic effects

CORAL DOMINATED

ALGAL DOMINATED

JAMAICA

OVERFISHING HURRICANE ALLEN 1980 ACROPORA DIE­OFF 1980S DIADEMA DIE­OFF 1983

JAMAICA

MORE ALGAE NO GRAZERS LESS CORAL PHYSICAL DAMAGE

SYNERGISTIC  EFFECTS

ALGAL DOMINATED

BUCK ISLAND, ST. CROIX

PROTECTION SINCE 1961 ACROPORA DIE­OFF 1980S DIADEMA DIE­OFF 1983 HURRICANE HUGO 1989 HURRICANES MARILYN/LUIS 1995

BUCK ISLAND, ST. CROIX

PROTECTION LITTLE OVERFISHING DISEASE PHYSICAL DAMAGE

CORAL DOMINATED