the dead zone:
DESCRIPTION
The Dead Zone:. Hypoxia in the Gulf of Mexico. What is the dead zone?. Condition that occurs in coastal waters where:. • Little or no oxygen is present • Little or no marine life can survive. The term for low oxygen is hypoxia . Hypoxia=TRANSCRIPT
![Page 1: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/1.jpg)
The The Dead Zone:Dead Zone:
Hypoxia in the Gulf of Hypoxia in the Gulf of MexicoMexico
![Page 2: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/2.jpg)
What is the What is the dead zone?dead zone?
![Page 3: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/3.jpg)
• Little or no oxygen is present
• Little or no marine life can survive
Condition that occurs in coastal waters where:
![Page 4: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/4.jpg)
The term for low oxygen is The term for low oxygen is hypoxiahypoxia..
Hypoxia=<2 mg/l dissolved oxygen Hypoxia=<2 mg/l dissolved oxygen (DO)(DO)
![Page 5: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/5.jpg)
The term for no oxygen is The term for no oxygen is anoxia.anoxia.
Anoxia =0 mg/l dissolved oxygenAnoxia =0 mg/l dissolved oxygen
![Page 6: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/6.jpg)
Where does Where does hypoxia occur?hypoxia occur?
![Page 7: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/7.jpg)
Hypoxia occurs all over the world in coastal waters.
![Page 8: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/8.jpg)
United States Canada France Italy Greece Turkey Russia Sea of Azov Adriatic Sea Aegean Sea Mediterranean Sea
Ireland Scotland Sweden Norway Finland Spain Germany Japan Hong Kong Australia New Zealand
![Page 9: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/9.jpg)
![Page 10: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/10.jpg)
In the U.S., hypoxia occurs in coastal waters in New York, Maryland, North Carolina, Florida, Alabama, Texas and Louisiana.
![Page 11: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/11.jpg)
In Louisiana, the dead zone occurs west of the Mississippi and Atchafalaya rivers
![Page 12: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/12.jpg)
When does the When does the dead zone dead zone
occur?occur?
![Page 13: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/13.jpg)
In Louisiana, hypoxia occurs from late spring until late summer.
![Page 14: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/14.jpg)
Why is the Why is the dead zone dead zone a problem? a problem?
![Page 15: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/15.jpg)
The dead zone can affect:
• Benthos• Fisheries• People
![Page 16: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/16.jpg)
• Stressed or die• Decreased diversity• Degraded environment
Benthos
![Page 17: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/17.jpg)
• Food base is reduced and/or lost• Habitat is reduced and/or lost • Recruitment is disrupted• Migratory patterns are disrupted • Species diversity is reduced • Mortality increases
Fisheries
![Page 18: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/18.jpg)
• Commercial fisheries
• Recreational fisheries
• Tourism
• Economy
People
![Page 19: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/19.jpg)
The dead zone decreases the ability of the Gulf to produce seafood. This affects the local economy.
![Page 20: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/20.jpg)
Louisiana has one of the largest coastal dead zones in the world.
![Page 21: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/21.jpg)
How large is Louisiana’s dead zone?
![Page 22: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/22.jpg)
Since 1985, the dead zone has ranged in size from about 100 square miles in 1988 to over 8,500 square miles in 2002.
![Page 23: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/23.jpg)
The size of the dead zone depends upon the conditions that cause it.
![Page 24: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/24.jpg)
What What causes causes
hypoxia?hypoxia?
![Page 25: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/25.jpg)
A combination of physical, chemical and biological factors create conditions for hypoxia in Louisiana.
![Page 26: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/26.jpg)
Warm spring and summer temperatures heatthe water surface.
Warm Temperatures
![Page 27: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/27.jpg)
Calm seas decrease oxygen exchange at the surface.
O2
![Page 28: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/28.jpg)
Nutrients
Warm fresh water and nutrients are delivered by the Mississippi River and float on the denser saltwater.
![Page 29: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/29.jpg)
A stratified layer is formed with lighter, fresher, warmer water at the surface and heavier, saltier, cooler water near the bottom limiting oxygen mixing throughout the water column.
Lighter Fresher WarmerWater
Stratified Layer Heavier
Saltier Cooler Water
No O2 mixing
![Page 30: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/30.jpg)
The Mississippi River drains 41% of the lower 48 United States. It carries water and sediment hundreds of miles to the Gulf of Mexico.
![Page 31: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/31.jpg)
The Mississippi River also carries nutrients.
![Page 32: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/32.jpg)
Excess nutrients from runoff are carried to the Gulf of Mexico.
![Page 33: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/33.jpg)
Nutrients include compounds which contain:
• Phosphorus
• Nitrogen
• Silica
![Page 34: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/34.jpg)
Nutrients that are carried by the river come from a variety of sources.
![Page 35: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/35.jpg)
Fertilizers
Cattle, pig and poultry farm runoff
Atmosphere
Wastewater treatment
Municipal & industrial runoff
![Page 36: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/36.jpg)
Microscopic algae or phytoplankton use these nutrients to reproduce.
![Page 37: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/37.jpg)
Excess nutrients enable plankton populations to explode, causing a plankton or algal bloom.
![Page 38: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/38.jpg)
At the surface, plankton blooms occur when excess nutrients are present
Plankton bloom
![Page 39: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/39.jpg)
When plankton die, they sink and decompose
![Page 40: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/40.jpg)
When plankton die, they sink to the bottom and decompose.
During decomposition bacteria use up most or all of the available oxygen.
Dead Plankton
No O2 Decomposers
![Page 41: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/41.jpg)
During decomposition, bacteria use up most or all of the oxygen causing the water column to become hypoxic or anoxic.
![Page 42: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/42.jpg)
Stationary animals become stressed and/or die
Mobile animals become stressed and leave
![Page 43: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/43.jpg)
When little or no oxygen is present:
•Mobile animals leave.
•Stationary animals become stressed or die.
![Page 44: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/44.jpg)
Fresh River Water
Warm Temperatures
Plankton Bloom
Dead Plankton
No O2
Lighter, Fresher, Warmer, Water
Stratified Layer Heavier
, Saltier, Cooler, WaterDecomposer
s
O2
No O2 Mixing
Nutrients
![Page 45: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/45.jpg)
![Page 46: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/46.jpg)
Human activities contribute to the causes of hypoxia
![Page 47: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/47.jpg)
• Land use practices• Fertilizer use• Poor management practices
![Page 48: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/48.jpg)
AgricultureIndustryFlood controlUrban expansion
Lead to:Loss of natural habitat
Changes in land use from
![Page 49: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/49.jpg)
What can What can be done?be done?
![Page 50: The Dead Zone:](https://reader036.vdocuments.us/reader036/viewer/2022062315/56815476550346895dc28dfa/html5/thumbnails/50.jpg)
• Change flood control practices• Use fertilizers more efficiently• Control discharges of nitrogen • Create and restore wetlands• Reduce nutrient loading• Manage the whole system