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sixcageyMechanics

Feb 22, 2014 (3 years and 6 months ago)

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Human
Impacts on
Coral Reefs

Natural Stresses
and Human Uses

What is Coral
Reef?


Symbiosis between
polyp and
photosynthetic algae


Excrete calcium
carbonate
(limestone) as
polyp’s shell

Global Distribution of Reefs

Factors Correlated with
Healthy Coral Reef Growth


water temperature range: 18


29

C


normal seawater salinity: 32


35 ‰


low inorganic nutrient concentrations
(oligotrophic waters)


clear, transparent water


little or no sedimentation


vigorous water motion

Human Impacts
on Coral Reefs

Thursday, October 26, 2006


Massive loss of coral reefs is predicted

By Matt Probasco THE ASSOCIATED PRESS


CHARLOTTE AMALIE, U.S. Virgin Islands


Researchers fear more than half the world’s coral
reefs could die in less than 25 years and say global
warming may be at least partly to blame.

Last year’s coral loss in the Caribbean waters
supports predictions that 60 percent of the world’s
coral could die within a quarter century, said Tyler
Smith of the University of the Virgin Islands
.



Up to 30 percent of the world’s coral reefs have
died in the last 50 years, and another 30 percent
are severely damaged, said Smith, who studies
coral health in the U.S. Virgin Islands and
collaborates with researchers globally.


Report: Caribbean coral reefs down
80 percent

By Marsha Walton

CNN

Thursday, July 17, 2003



(CNN)
--

A new study paints a grim
picture of the health of coral reefs
across the Caribbean. In the past three
decades, the amount of coral cover has
dropped about 80 percent, according
to researchers in the journal Science.


20% of coral reefs were lost and an
additional 20% were degraded in
just the last several decades of the
twentieth century.

Source:

United Nations Environment Programme (UNEP). 2005.
Millennium Ecosystem Assessment


Natural Sources of Stress on
Coral Reefs


intense storms


El Niño


disease


volcanic eruptions


predator population explosions


natural stream and river runoff


exceptionally low tides

Storm Wave Damage

Before

After

Storm Damage

Disease

Stream and River Runoff

Human Impacts on
Coral Reefs

Some Local Human Impacts


thermal effluents


sewage discharges and agricultural runoff


mechanical damage to reefs


sedimentation


destructive resource extraction practices


introduced species


loving a reef to death

Global Human Impacts


global warming


excessive carbon dioxide
in atmosphere


ozone depletion

Possible Consequences of Stresses
and Impacts on Corals and Coral Reefs


outright mortality of coral tissues


breakage of coral colonies


bleaching


diseases


slower growth


competitive exclusion by other organisms


increased reef erosion

Coastal Development

Modern Uses of Coral Reefs


Seafood


Food Additives and Toiletries


Health and Medicine Products


Research and Education


Jewelry and Art


Marine Aquarium Specimens


New Land


Cement & Other Building Supplies


Shoreline Protection


Recreation

Coral Bleaching

Global Bleaching

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.)

Sea Level Rise

Sewage Discharge
and Agricultural
Runoff

Sewage Discharge and
Agricultural Runoff


ecological consequences


phytoplankton bloom reduces light
penetration and promotes growth of filter
-
feeding bioeroders


benthic seaweeds overgrow and smother
corals

Nutrients and Algae Growth

Toxic Chemical Spills

Other Wastes

Dredging

Mining of Reef Limestone

Anchor Damage

Diver
Damage

Net Damage

Atomic Testing

Sediment
Runoff

Sediment Plume Entering the Ocean

Corals Smothered in Sediment

Destructive Resource
Extraction Practices


overfishing


use of dynamite to catch fish


use of bleach or cyanide to catch fish


breakage of coral to remove fan worms


collection of live coral or rocks

Dynamiting Reef

Introduced Species

Acanthophora, Eucheuma, & Gracillaria

Loving a Reef to Death


walking on reefs


diver damage


fish feeding


excessive recreational use

Feeding Fish

Hanauma Bay

Non
-
Point Source Pollution

Types of Non
-
Point Source
Pollution


sediments from coastal urban and
agricultural development


nutrients from detergents, fertilizers, leaky
septic tanks, and domesticated animals


pesticides (home use, agricultural, & golf
courses)

Types of Non
-
Point
Source Pollution


automobile wastes such as
combusted motor oil, tire rubber,
brake pad dust, coolant, etc.


waste water from swimming pools
and aquaculture ponds