Mississippi River
Bottomlands, Levees, Estuaries, Gulf Hypoxia
Michael Pohlmann, Chad Ketcham, Phillip Tilson, Bradley Schmitz
Bottomlands/Floodplains
• Low-lying forested and marsh areas extending
away from a river or stream. Subjected to
periodic flooding.
• Historically extremely biodiverse.
• Critical habitat for numerous species of bird
and amphibians. (perhaps most threatened)
Ecological Challenges
• Agriculture- nutrient runoff, Ag-chemical, soil erosion,
physical destruction of habitat
• Industry- dumping, transportation requiring channel
manipulation and extensive lock/dam system.
• Hydrologic control- levees, lock/dam systems, canals,
settling basins.
Restoration
• Restoration is slow and complex.
• Large-scale planting efforts, restoring some
natural hydrologic systems, ID of threatened
endangered plant & animal species.
• Best approaches are multi-facetted:
– Establishment of refuges
– Planting Efforts
– Reintegrating hydrologic and nutrient cycles (allowing
natural floods to occur)
Sunset Marina, Rock Island IL
What are
Levees?
http://img.search.com/thumb/6/69/Sacrament
o_River_Levee.jpg/400pxSacramento_River_Levee.jpg
http://islandbreath.org/2007Year/08technology/0708-06HanapepeLevee.jpg
http://www.cement.org/water/images/slurry_levee.jpg
“A manmade barrier (embankment, floodwall or structure)
along a watercourse constructed for the primary purpose to
provide hurricane, storm, and flood protection relating to
seasonal high water, storm surges, precipitation and other
weather events; and that normally is subject to water loading
for only a few days or weeks during a year”.
(http://www.leveesafety.org/ip_leveedefinition_22March11.cfm)
Levees and the Mighty Mississippi…
• The main stem levee system is 2,203 miles
long. (Along with thousands of miles of side
channels.)
• The levees are constructed by the feds and
maintained by local interest groups.
• Periodic inspections are performed by the
Army Corps of Engineers.
http://www.mvn.usace.army.mil/pao/bro/misstrib.htm
Levees and Natural Wetlands…
• As we have seen a levee separates the river from the
surrounding land.
• Wetlands could possibly dry up.
• Native plants and animals disappear.
• Soil no longer gets the nutrients it needs from the
main river which in turn causes invasive non-native
plants to take hold.
Estuaries of Louisiana
WHAT IS AN ESTUARY???
• Estuaries are bodies of water that are located where rivers
meet the sea.
• Contain a diversity of plants and animals due to brackish
water, ( mixture of freshwater from land and salty seawater).
• One of the most productive ecosystems in the world. Provide
food, nesting, breeding, jobs, recreation and housing.
• Of the 32 largest cities in the world, 22 are located in estuaries,
ex , New York and New Orleans.
Problems of Louisiana Estuaries
•
•
•
•
•
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Pathogens
Toxic Substances
Changes in Living Resources
Eutrophication
Habitat Loss
Sediment Reduction
Importance
• Environmental- provide habitats for amphibians,
reptiles, birds, fish, insects, and other wildlife.
• Economic-recreation, fish market, transportation,
housing and tourism
• Ecosystem- habitat protection and water filtration.
What is Being Done
• BTNEP (Barataria-Terrebone National Estuary
Program)
• Designed to conserve, restore and protect the
current Louisiana Estuaries.
Gulf of Mexico’s “Dead Zone”
• Region is so depleted of oxygen
that marine organisms are killed
or driven away.
• Hypoxia – low concentrations
of dissolved oxygen in the
bottom of waters
• Aquatic animals obtain oxygen
by respiring through gills.
• Low concentrations of oxygen
cause animals to asphyxiate.
Causes
• Nitrogen, Phosphorous,
and nutrients are flushed
down the Mississippi
River and Atchafalaya
River into the Louisiana
Coast.
• Fertilizers, urban runoff,
industrial discharges,
fossil fuel emissions, and
municipal sewage outflow
pollute the River and are
deposited in the Gulf of
Mexico.
Eutrophication
1.) Enhancing the amount of nitrogen increases the growth of
phytoplankton (photosynthetic algae), protists, and cyanobacteria
that drift near the surface.
2.) Zooplankton consume large amounts of phytoplankton. The
waste products and dead phytoplankton drift to the bottom of the
ocean floor.
3.) Bacteria decomposers consume the dead organic matter.
Bacteria populations increase and cause oxygen concentration in
the water to decrease significantly as the bacteria consume
oxygen.
4.) Low concentrations of oxygen suffocate shrimp and fish
creating the “Dead Zone.”
Eutrophication
Problems
Fisherman and Coastal Economies
• 72% of U.S. harvested Shrimp
• 66% of U.S. harvested Oysters
• 16% of U.S. Commercial fish
Loss of Biodiversity
Toxicity of Algae Blooms – Neurotoxins and Hepatotoxins kill
animals and pose threat to humans
• Shellfish take up toxins, then humans eat shellfish leading to
paralytic, neurtoxic, and/or diarrhoetic shellfish poisoning
Solutions
• Use
fewer fertilizers
• Limit runoff from farms
• Change Cropping systems and timing
• Switch from traditional crops (corn/
soybean) to alternatives
• Monitor Septic Systems and Sewage
Treatment
• Limit Discharges of nutrients, organic
matter, and chemicals from
facilities
• Human made Wetlands and Riparian
Buffers
• Flood Control
• Mississippi River diversions
• Biosurfactants (Soap from bacteria)
Works Cited
• http://oceanservice.noaa.gov/education/tutorial_estuaries/est03_ecosystem.
html
• http://oceanservice.noaa.gov/education/tutorial_estuaries/est02_economy.ht
ml
• http://www.epa.gov/owow_keep/estuaries/pivot/2009barataria_terrebonne.
html
• “Status, Trends, and Probable Causes of Change in Living Resources in the
Barataria-Terrebonne Estuarine System.” Publication #21 BTNEP. 1996.
Condrey, Kemp and Visser.
• “Healthy Estuary, Healthy Economy, Health Communities.” BTNEP. 2002,
Thibodaux, LA.
Works Cited Cont.
• ”Dispersing Oil the Natural Way, Using Biosurfactants and Resident Marine
OrganismsEcology Today: Ecology News, Information & Commentary Blog." The
Ecology Global Network | Ecology News and Information for Residents of Planet
Earth. Web. 19 Sept. 2011. <http://ecology.com/ecologytoday/2010/07/12/dispersing-oil-the-natural-way-using-biosurfactants-andresident-marine-organisms/>.
• Diaz, Robert J. "Spreading Dead Zones and Consequences for Marine Ecosystems."
Science 321 (2008): 926. Sciencemag.org. Science AAAS. Web. 11 Sept. 2011.
<http://www.sciencemag.org.ezproxy2.library.arizona.edu/content/321/5891/926.f
ull>.
• "The Gulf of Mexico Dead Zone." SERC. Web. 19 Sept. 2011.
<http://serc.carleton.edu/microbelife/topics/deadzone/>.
• Mitsch, William J. "Reducing Nitrogen Loading to the Gulf of Mexico from the
Mississippi River Basin: Strategies to Counter a Persistent Ecological Problem."
Bioscience 51 (2001): 373-88. JSTOR. Web. 11 Sept. 2011.