Hurricane Protection Water Treatment

Biogeochemical Cycling Habitat

Hurricane Protection
Written by Sara Barnowski

In their natural state wetlands are not completely saturated with water.  However, their potential for storing floodwaters and storm surge is great.  According to a report by American Rivers, a single acre of wetlands, saturated to one foot, can hold up to 330,000 gallons of water (DeVries,Brad).  After Hurricane Katrina the Army Corps of Engineers removed about 250 billion gallons of water from the New Orleans area (Solis, Lauren ).  This would require close to eight hundred thousand acres of healthy wetlands to be completely remediated by nature.  At one time these wetlands may have existed, but they have rapidly been lost to subsidence, erosion and development.  It is of the utmost importance to restore and rebuild the Louisiana wetlands because they are our first line of defense against future floods and hurricanes.

    The ecological makeup of wetlands causes them to act as natural water purifiers, removing sediment, nutrients, and toxins from the water flowing through them.  Filtering effluent through the natural system not only purifies the wastewater, but also accelerates vegetation growth and accretion rates. The addition of effluent also increases the accretion levels of the ecosystem, which offsets the effects of subsidence, and can raise the wetlands at the same rate as the relative sea level rise (about 12 mm per year combined sea level rise and subsidence).  This is extremely important in an area where the land is at approximately the same height as the ocean (Day, J.W., 2005).  Local communities and businesses can utilize the wetlands as facilities for the treatment of wastewater.  Not only would this would be beneficial to the wetland ecosystem, but it would also be economically beneficial for the community.  Using the natural world for wastewater treatment saves money in energy costs, since it requires no electricity to process the effluent, and no fuel to transport it far away for treatment or storage.  Recent studies show that this savings can amount to between $500,000 and $2.6 million. (Day, J.W., 2005)

Wetlands play a huge role in biogeochemical cycling.  They supply nitrogen, sulfur, phosphorus, and carbon to surrounding ecosystems.  Further, they are capable of storing such elements for long periods of time in the soil. 

Carbon is taken from the air as CO₂ and used in photosynthesis, but instead of later being released again as carbon dioxide, wetlands are capable of storing carbon in the sediment in the form of deteriorating organic substances.  This storage technique allows wetlands to help decrease the greenhouse effect (Faulkner, 2004). 

Nitrogen is largely cycled within the wetlands’ soil, but also escapes to neighboring ecosystems.  Thus wetlands provide nutrients not only for their own uses, but for use by other systems as well.  Phosphorus and sulfur are also cycled within wetlands and transported to other environments.  These cycles rely on the oxygen and pH levels within the water.  If the system is put under stress, wetlands can release toxic gases such as H₂S.  Due to the role wetlands play in supplying nutrients to other ecosystems, healthy wetlands are important for the survival of many communities (Faulkner, 2004).

Coastal Louisiana is home to several different types of wetlands, with diverse physical and biological characteristics.  The dominant factors in determining the conditions of wetlands include the salinity, substrate type, and the energy level of the water. Wetland ecosystems are generally defined as the areas between terrestrial and aquatic or marine ecosystems.  Although at first glance, wetlands might appear to be an extremely difficult environment to inhabit, due to their shifting sediment, variable water levels, and anaerobic soil, they are one of the most productive types of ecosystem on earth.  Part of the reason for this is that compared to other aquatic or marine environments, their shallow depths allow for rapid nutrient cycling, and allows marine plants and algae to attach to the substrate. Additionally, there is generally a high concentration of phytoplankton and benthic algae.

 

Species of the genus Spartina are the most common native plants in the Louisiana wetlands.  The most abundant of these is smooth cordgrass, a vascular, grass-like plant particularly well-adapted for the environment of Louisiana’s coast.  Some of the larger wetland species include cyprus, which are found in predominantly freshwater areas (Mitsch and Gosselink), and mangrove, which are found in certain coastal areas and barrier islands.  These create habitat for a large variety of other plants and animals.

 

Significant plant growth in wetlands translates into a large amount of animal species such as crustaceans, fish, mollusks, insects, amphibians, and mammals. This staggering amount of biomass is the key to wetlands’ economic value.  Wetlands tend to be spawning and nursery areas, often for commercially important fishes and shellfish. They provide food and economic value to many Louisiana communities.  The wetlands are also home to several species of mammals, including nutria, muskrat, mink, raccoon, otter, bobcat, beaver, coyote and opossum.  Many of these species are harvested for their pelts (Geography: Coastal Louisiana Basins, 2006).  In addition, Louisiana's wetlands provide shelter to several threatened and endangered species, including the brown pelican and bald eagle.  The wetlands also house many migratory birds on their way from North America to South America.  Louisiana’s freshwater wetlands are also home to alligators.  Unfortunately, as the wetlands are degraded and lost, their biodiversity goes with them.