Dead Zones are oxygen starved areas in the world's oceans that cannot support life
(Howarth 2000, msnbc.com). The reason these dead Zones form is because excess amounts of nitrogen and phosphorus find
their way into the oceans and create algal blooms (Howarth). The algae then uses up all the oxygen in the water and
basically suffocates bottom-dwellers like snails, oysters and clams. This also causes fish, crabs and shrimp to relocate
(Daler, Daoji, 2004). Currently, there are 146 known dead zones in the world, but, that number is bound to increase
unless the levels of nitrogen and phosphorus that are released into our oceans is greatly reduced (Howarth et al.,2000,msnbc.com).
This page focuses on the major causes and effects of dead zones and what can be done to reverse them.
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| http://www.tripod.lycos.com |
Causes of Dead Zones:
Some of the major causes of Dead Zones are agricultural fertilizers, fossil fuel burning
and improper disposal of sewage and solid waste (Daler 2004, Howarth 2000).
Agricultural Fertilizers:
Agricultural Fertilizers are the leading cause of the increased release of Nitrogen
into our oceans. One-third of our land is used for agriculture. In most cases, crops are grossly over fertilized
in the hopes of better harvests. Unfortunately, this over fertilization has disastrous effects on marine life.
The run-off of crop fertilizers makes its way into our lakes, rivers and streams which all eventually empty into our oceans
(Daler 2004, Vitousek 1997). Also, animals that feed off of these over fertilized crops produce waste that contains
higher than normal levels of nitrogen (Howarth 2000).
Fossil Fuel Burning:
Examples of Fossil Fuels are coal, oil and natural gas. These are usually
found in geological formations and have been confined for millions of years. When these fossil fuels are extracted by
humans and burned, they release previously fixed nitrogen into the atmosphere that, under natural conditions, would
never have been released. Automobile exhausts are a prime example of fossil fuel burning (Vitousek 1997).
Sewage and Solid Waste:
Sewage and Solid Waste have become a major problem, not only in the United States,
but all over the world. In some countries there is virtually no waste disposal system. Urban areas are littered
with solid waste. Some countries, such as China, have their sewage emptied directly into our oceans. Coastal area
populations are growing and will continue to increase the amounts of sewage and solid waste that are poisoning our oceans
(Daler 2004).
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| Mississippi River emptying into the Gulf of Mexico.http://www.msnbc.msn.com/id/4624359 |
Effects of Dead Zones:
The effects of Dead Zones are numerous. The excess Nitrogen and Phosphorous
released into our oceans wipes out entire ecosystems. They produce uninhabital areas of our coastal waters that once
thrived with life. They have endangered species in many areas, caused the fishing industry to plummet and has forced fish
to relocate and compete with other species for space. It also contributes to the loss of diversity along the sea floor
and among organisms. They cause fish death, poisoned shellfish, which in turn can poison humans if eaten and also cause
allergic skin reactions in humans (Daler 2004,Vitousek 1997).
What can we do?
There are many things we can do to decrease the release of Nitrogen and Phosphorus
into our oceans which will in turn decrease the size and number of Dead Zones.
~ We can decrease the production and over-use of Nitrogen Fertilizers.
~ We can educate agricultural farmers on the proper usage of fertilizers and the harmful
effects they cause if used incorrectly.
~We can help educate other countries on better ways to handle their sewage and waste
problems and show them the damage that dumping into the ocean causes.
~We can carpool and reduce the amounts of fossil fuels that are burned and released
into our oceans.
~Use organic fertilizers instead of nitrogen fertilizers on gardens and lawns to reduce
the amount of nitrogen released into our waters.
~Support and contribute to research done on this subject.
~Be Aware of your own contributions to this problem!! Every person counts, do
your part and help save our oceans!
(Daler 2004, Howarth 2000, Obura 2004, Vitousek 1997)
This site only describes a few of the many causes and effects of Dead Zones.
Hopefully, we have made you aware of the disastrous consequences that result from our everyday activities and what you can
do to help reverse this terrible cycle. Please follow the links below to learn more about Dead Zones in the world and
how you can help. Thank-you!!
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