The Mississippi River Deltaic Cycle

Water flows downhill naturally and, over time, will make a river change from one path to another. As sediment moved and elevations changed over the last 7 millennia, the Mississippi River has emptied into several historic delta complexes: Maringouin, Teche, St. Bernard, Lafourche, Plaquemines-Balize, and Atchafalaya. Each of the deltas built up part of Louisiana’s coast to what we see today, but now that natural process has been interrupted [1]. After the great Mississippi flood of 1927 that caused $1 billion worth of damages (almost $1 trillion in today’s dollars), the US Army Corps of Engineers built the world’s longest levee system under the Flood Control Act of 1928. The Levee system was constructed to reduce flood damages and allow for more control of the Mississippi [2].

Image 1: Historic Deltas of the Mississippi River

An unforeseen and unfavorable side effect to taming the river was that all the water is kept moving too quickly to deposit sediment, and now sediment is lost to the Gulf of Mexico rather than deposited into our coastal wetlands [3]. Our Louisiana coastline is dependent on new sediment to nourish wetland ecosystems. Without sediment delivery, there is no material for natural land gain or replenishment, which will continue to contribute to our retreating coastline. The solution is not as simple as removing the levee system, however, since so much of Louisiana is populated now, and removing the levees containing the Mississippi would displace millions of residents from their homes. Instead, CWPPRA and our partners in restoration use man-made systems to create marsh, nourish wetlands, and maintain hydrologic connectivity so that we can protect and restore Louisiana’s coast.

 

 

[1] https://en.wikipedia.org/wiki/Mississippi_River_Delta

[2] https://en.wikipedia.org/wiki/Great_Mississippi_Flood_of_1927

[3] http://mississippiriverdelta.org/our-coastal-crisis/wasted-sediment/

Image 1 from https://www.nationalgeographic.org/photo/miss-delta-formation/

Featured image from https://phys.org/news/2015-04-future-mississippi-delta.html

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Prothonotary Warblers

 

As April passes into May, many migratory birds leave the tropics of Central and South America in search of bountiful summer resources in the sub-tropical United States. Among them, the very charismatic Prothonotary Warbler flies from the northern tropics to the hospitable habitats of the United States. Prothonotary warblers live in forests near bodies of slow-moving water where they can hunt for insects and nest in cavities in trees. The cypress swamps of Louisiana are about as good as it gets for a prothonotary warbler, and they stay from April to August. [1] If you get out into the swamp during the summer, look for their bright yellow figures darting through low-lying foliage.

Prothonotary warblers have experienced a population decline in recent years that experts attributed to the destruction of their wintering habitat in the tropics.[2] To improve breeding success and survivorship, the Audubon Society and other ornithological enthusiasts have encouraged people to install nest boxes that help to protect warbler nests from failing. Many natural threats exist in swamps for warblers, including a variety of snakes, birds of prey, and mammals. Since brown-headed cowbirds will use prothonotary nests to lay their eggs in when given the chance, nest boxes are suggested to have a 1¼“ hole to prevent larger birds from entering the box but still allow the warblers to enter. Boxes are not left on the ground, and are often mounted on poles. Some predators can climb, so many boxes have a skirt/collar that prevents snakes, raccoons, and cats from climbing the poles into the nests. More guidelines for a good nest box can be found at https://nestwatch.org/learn/all-about-birdhouses/features-of-a-good-birdhouse/.

 

 

[1] Petit, L. J. (1999). Prothonotary Warbler (Protonotaria citrea), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.408

[2] Kaufman, Kenn. “Prothonotary Warbler.” Audubon, National Audubon Society, 10 Mar. 2016, http://www.audubon.org/field-guide/bird/prothonotary-warbler.

Featured Image:

Brannon, Peter. “Adult Male.” All About Birds, The Cornell Lab of Ornithology, Florida, 14 Sept. 2016, http://www.allaboutbirds.org/guide/Prothonotary_Warbler/id.

UL-Lafayette Fête de la Terre

What better way to spend a Friday afternoon than with jambalaya, Cajun music, and conservation? That is how the CWPPRA outreach team and many other organizations spent last Friday, April 20th, at the UL-Lafayette Fête de la Terre Expo. The expo showcased many wonderful local groups including, but not limited to, the Citizens’ Climate Lobby, the TECHE Project, and the Bayou Vermilion District, all hosted by the ULL Office of Sustainability.

Students visiting the expo could learn about how long it takes for different types of litter to decompose naturally, how solar panels are used to generate power, and whether or not to recycle different waste products. During their visit, they could grab free jambalaya, listen to the Cajun jam session, or decorate their very own reusable grocery bag. There are so many resources that help our community celebrate conservation, and the expo was a beautiful day for getting ULL students and faculty involved, interested, and informed.

 

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Black Bayou Culverts Hydrological Restoration (CS-29)

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The marsh within this area has been suffering from excessive water levels within the lakes subbasin that kills vegetation, prevents growth of desirable annual plant species, and contributes to shoreline erosion. Black Bayou offers a unique location in the basin where the water in the lakes subbasin and the outer, tidal waters are separated by only a narrow highway corridor.

Project components include installing ten 10 foot by 10 foot concrete box culverts in Black Bayou at the intersection of Louisiana Highway 384. The structure discharge will be in addition to the discharges provided by Calcasieu Locks, Schooner Bayou, and Catfish Point water control structures.

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The project features are located in southern Calcasieu Parish, Louisiana. The majority of the project area is located east of Calcasieu Lake and includes areas north of the Gulf Intracoastal Waterway and west of Grand Lake in Cameron Parish, Louisiana.

Construction has been completed.

This project is on Priority Project List 9.

Federal Sponsor: NRCS

Local Sponsor: CPRA

Salinity Stress and Tolerance

Living in any habitat comes with hurdles that make it harder for plants and animals to thrive. We call these hurdles “stress”. Coastal wetlands demonstrate several kinds of stresses to both plants and animals. Through many years of evolution, plants and animals have adapted to living with these stresses, also called being “stress tolerant”. Adaptations can be in physical structure changes or on the smaller scale (cellular). Some stresses that come with living in coastal wetlands include salinity (the amount of salt or ions in the water), inundation (flooding at least above the ground, sometimes even higher than the whole plant), and hypoxia (low dissolved oxygen in the water). [1]

Salt water intrusion has been increased by dredging navigation channels among other impacts. Saltwater intrusion makes fresh bodies of water more saline than they usually are. The problem with this is that the plants that live in such places are adapted to live in fresh water and generally cannot deal with increases in salinity more than 1 or 2 parts per thousand (ppt). For reference, the Gulf of Mexico’s average salinity is approximately 36ppt. Some plants, though, can live in full-strength sea water. For example, the black mangrove (Avicennia germinans) has several adaptations that let it keep its cells safe from high salinity. Like smooth cordgrass (Spartina alterniflora), black mangroves excrete salt onto their leaves to get it out of their systems.[2] Some fish have similar adaptations in their gills that allow them to keep their internal salt concentrations at safe levels.

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Salt Crystals accumulate on A. germinans leaves (Photo by Ulf Mehlig, found on Wikimedia Commons)

 

Works Cited:

[1] Bradford, Nick. “Stressed Wetlands.” NEEF, 10 May 2016, http://www.neefusa.org/nature/land/stressed-wetlands.

[2] Gilman, Sharon. “Plant Adaptations.” ci.coastal.edu/~sgilman/778Plants.htm.

Featured image is of A. germinans from Wikimedia commons, courtesy of Judy Gallagher

South Grand Chenier Marsh Creation (ME-20)

ME-20_bannerThe major problem in the Hog Bayou Unit is land loss caused by failed agricultural impoundments and pump-offs. Other problems include saltwater intrusion from the Mermentau Ship Channel and a Gulf shoreline erosion rate of 40 feet per year. Over a period of 60 years, 9,230 acres (38% of the original marsh) was lost from the Hog Bayou Watershed, with the greatest amount of land lost between 1956 and 1974.

The major contributors to land loss in the Watershed are subsidence, compaction, and the oxidization of marsh soils in the former pump-offs and leveed agricultural areas between Hog Bayou and Highway 82. Large areas of marsh south of Highway 82 were “force drained” during the 1960s, 1970s, and 1980s. Many of these same areas now consist of open water with very little wetland vegetation. One of the largest areas of current loss is in and north of the project area.

The project’s goal is to create 430 acres and nourish 23 acres of emergent brackish and intermediate marsh. The project goal will be achieved by using dredged material from the Gulf to create two marsh creation cells (176 acres and 277 acres) in the project area east and west of Second Lake.

The project is located south of Grand Chenier in Cameron Parish, Louisiana, between Louisiana Highway 82, Hog Bayou, and east of Second Lake.

ME_20This project was selected for Phase I (engineering and design) funding at the January 2002 Task Force meeting. It is included as part of Priority Project List 11. Engineering and design is complete. Construction funding will be requested in 2013.

This project is on Project Priority List (PPL) #11.

The South Grand Chenier Marsh Creation’s three sponsors include

The People of Louisiana’s Coastal Wetlands

The Coastal Wetlands Planning, Protection and Restoration Act leads the fight against Louisiana’s disappearing coast. The native people of coastal Louisiana are greatly worried about losing their homes, sources of livelihood, and culture if the lands they live on continue to disappear. Saltwater intrusion, marshes becoming open water, and the disappearance of barrier islands and protective wetlands are a few of the challenges facing coastal communities. For centuries, marshes have served as home to numerous people: American Indian tribes, Vietnamese, Croatian Americans, and other groups. All of these coastal residents are familiar with the hardship of living in an area frequented by natural disasters. Most coastal residents have chosen to stay on their lands to defend and protect the ecosystem despite the extreme risks. Without the hard work and effort of diligent landowners and organizations like CWPPRA, coastal Louisiana would be vanishing at a much faster rate.

You can read Watermarks #48 People of the Coastal Wetlands to learn more about this topic.