Human Impacts on Coral Reefs

Part 3Global Impacts

The Greenhouse Effect

45% reaches the surface

25%5%

atmospherereflected

25%

Human-Produced Greenhouse GasesCarbon Dioxide (CO2)

Methane (CH4)Nitrous Oxide (N2O)

Ozone (O3)

Natural Phenomena

Upperatmosphereresearch satellite

Volcanicemissions?

Sea spray?

Directevidence

sunspots

Greenhouse Gases

Carbon Dioxide & Temperature

Year

Possible Impacts of Global Warming on Corals and Coral Reefs

• bleaching• eustatic sea level rise creating more

growth room for reefs• increased carbon dioxide may increase

reef primary productivity• increased storm damage• changes to patterns of terrestrial runoff• changes to ocean circulation patterns

Effect on Marine Life• Phytoplankton bloom due to light and

temperature cues• Changes will impact food web• Hypoxia may result

Effect on Fisheries• Migrations are in response to temperature• May impact fisheries

Effect on Corals• Coral bleaching • Leads to loss of habitat and food for reef-

dependent species

Global Bleaching (2002)

nonelowmoderatesevereseverity unknown

Some causes of coral bleaching

• Unusually high or low temperatures• Unusually high or low salinity• High amounts of visible or ultraviolet light• Sedimentation• High levels of nutrients (sewage, etc.)• High levels of toxins (pesticides, etc.)

CurrentsOceanic conveyor belt may change ocean currents • Currents carry plankton• Bring food and oxygen• Distribute eggs and larvae• Remove wastes and pollutants

Currents

Salinity• Animals have a narrow range of tolerance• Glacial melting inputs lots of freshwater

Salinity

Acidity• CO2 makes water acidic• Corals and other calcium carbonate species

can’t make skeleton• Impact on plankton development impacts food

web

Ocean Acidification

Temperature• Higher temperature results in less O2

- Results in hypoxia• Ice melting leaves no resting/hunting areas for

polar bears• Antarctic Krill impacts food web

Temperature

Invasive Species• Algae smothers coral• Invasive species out-compete natives

Invasive Species

Weather Events

More severe weather patterns• El Niño• Hurricanes • Mudslides• Forest Fires• Drought

Weather Events

Sea Level RiseSea Level Rise

Sea Level Rise

Projected Sea Level Rise

Effects of Sea Level Rise on Human Populations

Sinking Islands

Effects of Sea Level Rise on Human Populations

Sinking Islands

Kiribati Tuvalu

Artificial Islands a Solution?

Consequences: Worst Predictions

4-6o F increase (2-3oC) in 20-30 years

End of the Ice Age: 1oC per 500 yearsNow: 1oC per 10 years

Highest temperature in 2 million years

Temperature Rise

Melting: glacier & polar ice cap 11% in last 100 years

Sea temperature increase: 2oF increase = 2 ft (0.6 m) rise

Global WarmingGlobal WarmingGlobal Warming

http://www.glaciers.pdx.edu/Projects/LearnAboutGlaciers/ROMO/BasicsIceAges.htm l

Click on link

Global Warming

Ice Ages in Hawai`i

100 m sea level rise

Global Warming

Global Global WarmingWarming

100 m sea level rise

1 Meter Sea Level Rise Waikiki1 Meter Sea Level Rise Waikiki

http://www.soest.hawaii.edu/HMRG/FloodingOahu/index.phphttp://www.soest.hawaii.edu/coasts/sealevel/waikiki.html

• Destroys coastal habitat (e.g. salt marshes, mangroves)

• Destroys human property• Increases pollution• Decreases freshwater supply

Sea Level Rise

Ozone Depletion

Ozone (O3) in the Atmosphere

Absorption of Ultraviolet

Radiation by the Earth’s

Atmosphere

Cosmic RaysGamma Rays

X Rays Ultra-Violet

Visable Light

InfraredRadio Waves

Visable LightX Rays

Vacuum UV UVB100 200 300 400

Shortwave UV (UVC) A bsor bed by oz one i n E ar th ' s atmosp her e

M iddle- & L ongwave UV (UVB & UVA )V isibl e L ight & I nfrared

UVC UVA

Ultraviolet Radiation“A threat to the continuation of life”

2

Humans: DNA damageCancer

Crops: Productivity decreaseOcean plants: Death?

VisibleInfrared (IR) UV

Ultraviolet Radiation

stratosphericozone layer

CFCs: refrigerationelectronics

foam packagingspray propellants

destroy

UV

‘96: CFC decrease noticed2006: stabilization?

Antarctic Total Ozone Trend400

1950 1960 1970 1980 1990 2000 2010

300

200

100

0

Tota

l ozo

ne (D

obso

n un

its)

Ozone blocks UV

Size of the Antarctic ozone holeAverage Area: millions sq km

North America

Antarctica

Prediction: 50 years to return to 1980 size

1979 2001

30

20

10

0

Oct. 1979

Sep. 2012

8.2 million miles2

Naturally Occurring Ozone Destroying

Chemicals• nitrogen from soils and the ocean• hydrogen from atmospheric

water vapor• chlorine from the ocean

Human Produced Ozone Destroying Chemicals• chlorofluorocarbons• jet aircraft exhaust• other industrial chemicals

Human Produced Ozone Destroying Chemicals

Effects of UV on Living Things• damage to DNA resulting in mutations• damage to other biological molecules

– proteins: enzyme inactivation– lipids: disruption of cell membranes

and membrane transport systems

Corals and UV Radiation• decreased growth • decreased rates of calcification• transplantation experiments (deep corals

brought to the surface) demonstrate corals may be UV-sensitive (exhibit bleaching and increased mortality)

• coral sperm appears to be UV-sensitive (note spawning normally takes place at night)