Monday, December 5, 2011

Louisiana Wetlands and the Mississippi River Delta Part 2

A floating Louisiana marshland.  This wetland is characterized by thick mats of semi-floating grasses, sedges, rushes, and a few small shrubs and are important to alligators for hibernation   
Also within these areas is the famed alligator of the south.  The abundance of water and bird life of these swamps and marshes feed these gators, allowing them to grow to large sizes.  The wild gator grows about one foot a year until it reaches six feet, then growth slows considerably.  The longest lived gators can survive up to 90 years in extremely rare instances and reach 15 feet in length.  Gators over six feet are uncommon but gators less than this are often found in abundance.   During warm summer months when water temperatures are over 70 degrees gators can be found throughout the swamps and marshes, anywhere there is enough water.  However, in November water temperatures drop below 70 degrees and gators go into hibernation until early spring when the water warms up again.  Typically, water levels in these wetlands fluctuate with ocean tides and floods coming from upstream.  This is a problem for hibernating gators who need to hibernate in wet areas but cannot be submerged with flood waters.  Because of this, gators hibernate in floating grassy marshlands that float up and down with fluctuating water levels.  Gator hunting is a rather common practice in Southern Louisiana.  The game management agency allows one gator to be harvested per twenty acres of wetland.  I've been told this is a major meat source for rural Louisianans.  I personally have eaten gator fried, as jerky, and as sausage.  Fried gator is rather chewy, but the jerky and sausage are great.  I love both of them.  In-fact, I may like gator jerky better than beef jerky.
A Louisiana alligator found in a bayou.  
Underneath all these wetlands in the sediments is an abundance of oil and natural gas.  Over past decades these natural resources have been drilled and mined out of the sediments, resulting in the wetlands sinking and flooding with more water.  This flooding has killed wetland vegetation and caused the disappearance of  this habitat.  According to some sources an entire football field of Louisiana wetland is disappearing as a result of this every 38 minutes.  Historically, the Mississippi has also snaked its way back and forth across southern Louisiana depositing sediments in low laying areas everywhere it went.  Today, the Mississippi is highly channelized and controlled by the Army Corps of Engineers, preventing this nature controlled movement and deposition of the river.  So when wetlands sink, sediments from the river is not available to raise them back up again.  People from all professions and industries are still searching for solutions to this problem.

The red area of the ocean indicates areas of low oxygen known as the dead zone.  This dead zone is a result of  water pollution brought into the gulf by the Mississippi River.  Picture from Wikipedia.
As the muddy waters of the Mississippi pass through the Midwest and the South, some of the richest agricultural land in the world, sediments and fertilizer are washed into and pollute the river.  The vast wetlands of the Mississippi River delta capture much of this pollution.  As wetlands naturally do, they capture and filter out pollutants from water in an amazingly efficient manner.  However, as some of these wetlands disappear, and being the levels of pollution are so extremely high, much of the pollution works its way through the delta and is deposited into the Gulf of Mexico.  This immediately has the effect of "fertilizing" the Gulf, which may seem a good thing at first.  Fertilization of water by pollution is known as eutrophication, and results in large algal blooms.  Once this algae dies however, the decompose and consume all the available oxygen in the water.  As a result of these low oxygen levels, very little ocean life can survive in these areas, giving it the name "dead zone."  The dead zone in the Gulf where the Mississippi ends currently is the size of New Jersey and has had huge effects on sea life, including the fishing industry.
Sediment pollution causing the dead zone (right side) next to oxygenated waters (left side).
Despite the negative, the wetlands of Southern Louisiana are still a vast, amazing, and relatively healthy functioning ecosystem.  Even in their impaired state these wetlands are still intact and functioning as they should.  Of course, they could function better if the Mississippi was allowed to flow as it pleased rather than be controlled.  With the many towns and small settlements in the area, letting the Mississippi flow back and fourth across the delta would likely destroy many of these communities.  Controlling the Mississippi is also important to the shipping industry.  So simply restoring natural flow is not such as simple task.  Still, even in their present state these wetlands absorb and filter much of the pollution that is carried down the Mississippi as well as provide huge areas for wildlife and recreation.  Without these functions the current dead zone in the gulf would be much larger and have enormous impacts on the fishing industry.

While I was only able to spend one day exploring these wetlands, it made me hungry to experience them more.  These wetlands are an amazing place to which so many people, cultures, plants, birds, and animals call home.  All of these different aspects are tied together forming the diversely rich creole culture.  In the near future, I will be talking more about this creole culture with a post about a historic Mississippi river plantation.

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