Mangroves in Winter

The recent cold weather in Louisiana may have been the end of the road for some plants as temperatures dipped into the teens and stayed below freezing for full days. The hibiscus in your garden may have survived because you gave it extra insulation, but what about marsh plants? Louisiana salt marshes are home to black mangroves (Avicennia germinans), but this represents the very northernmost part of their range. Of the three mangrove species found in the continental United States [red (Rhizophora mangle), black, and white (Laguncularia racemosa)], black mangroves are the most cold-hardy, but they are still sensitive to winter weather- they generally cannot establish above 28° N and S latitude because winters are too cold (a sliver of the Birdsfoot Delta is below 29° N, so we really are at their limit).

The three mangrove species are also different in their tolerances for other environmental conditions: red mangroves establish in the intertidal zone, while black and white mangroves are found at higher elevations, and white mangroves can colonize areas with little to no soil. In Florida where all three species occur, mangrove zones can be defined from the water extending inland and up in elevation .

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Red mangroves are found in the intertidal zone, while black and white mangroves establish at higher elevations. Graphic from the Florida Museum of Natural History at the University of Florida (https://www.floridamuseum.ufl.edu/southflorida/habitats/mangroves/zonation/)

Black mangroves are an important component of Louisiana salt marshes, providing habitat to a variety of species. The complex root systems trap and collect sediment, limiting erosion and maintaining land. Juvenile invertebrates and fish find shelter among the roots, while seabird chicks, such as brown pelicans and roseate spoonbills, are protected from high water events and predators up in the branches.

CWPPRA projects that nourish barrier islands and create new marsh habitat help maintain black mangrove populations by providing new land for the plants to colonize; in turn, the mangroves help the new land persist in the face of wind and wave energy.

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CWPPRA Project Selection

          The planning process leading up to project selection includes the nomination of a project followed by development and evaluation of proposed projects based on engineering, environmental improvements, and economics.

          A general breakdown of CWPPRA Project Selection is as follows:

  • CWPPRA projects are brought to the Task Force by the public, local municipalities, state agencies, and federal partners.
  • In January and February, each year 10-20 projects from each of the four regions become Priority Project List (PPL) candidates.
  • Parish representatives then rank projects in each region, and by the end of the spring the Technical Committee selects 10 projects from the annual PPL candidate projects for further development.
  • Of these 10 candidate projects, the Technical Committee recommends 4 projects for the design phase (Phase I) at their December meeting.
  • The Task Force must approve the 4 projects for design at their next meeting in January.
  • Projects already in design can request approval to proceed to Phase II for construction, and the Technical Committee will recommend 1-4 of these to the Task Force. Ultimately, the Task Force approves 1-4 of the recommended projects for construction.
  • Following the Technical Committee’s meeting and PPL recommendations in December, the Task Force will meet to finalize the approved projects. This year’s Task Force meeting is scheduled for January 25th. 

          Stay up-to-date on the project selection for this year’s Priority Project List by visiting our website. You can read more about CWPPRA Project Selection in Understanding CWPPRA.

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Wetland Marshes

Marsh is a type of wetland that is continuously flooded with water. Emergent-soft stemmed vegetation is present in marsh due to the saturated soil conditions. In Louisiana, there are four types of wetland marsh: freshwater, intermediate, brackish, and salt. Marshes are classified according to the salinity of the water. The location of Louisiana marshes in relation to the Gulf of Mexico often directly correlates to the level of salt content in the water. Salinity also changes based upon rainfall, drainage, soil texture, vegetation, depth of water table, and freshwater inflow.

The salinity range for each marsh type is as follows:

  • Freshwater – 0 ppt (parts per thousand)
  • Intermediate – 0-5 ppt
  • Brackish – 5-15 ppt
  • Salt – 15 or greater ppt

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A wide variety of animals such as nutria, turtles, and many bird species can be spotted in the freshwater and intermediate marshes of Louisiana, as well as species of special concern like Louisiana black bears and Calcasieu painted crawfish. The exchange between freshwater and salt water is frequent in the state of Louisiana due to its close proximity to the Gulf of Mexico. An estuary is characterized by this mixture of freshwater and salt forming brackish water where many wetland species spend their juvenile lives. The estuaries of coastal Louisiana support economically important fisheries and provide important wildlife habitat. Crabs, fish, and shrimp are a few of the animals found in Louisiana’s salt marsh, and birds like brown pelicans and reddish egrets often nest in the shrubby vegetation bordering salt marshes. Each of these marsh types play a significant role. It is vital to keep these marshes healthy for them to maintain their value and support the people, plants, and animals of Louisiana.

 

 

Wetland Vegetation

Wetland ecologists often refer to wetland vegetation as the foundation of coastal restoration. Native plants and vegetative plantings both provide significant benefits to wetlands. Wetland plants build and stabilize soil, create habitat, purify water, and shield infrastructure. These plants tend to accumulate the thick mud of marshes which prevents the soil from washing away. Animals that live in wetlands depend on plants or plant-eating animals for their food supply. Without wetland vegetation, the supply chain would self-destruct. By absorbing nutrients and chemicals from the water and sediment, plants reduce toxins and groundwater contamination. Wetland vegetation is key to preventing shoreline erosion and reducing storm surge which affects the coastal infrastructure.

The Coastal Wetlands Planning, Protection and Restoration Act funds a variety of wetland enhancement projects, such as vegetative planting. Vegetative planting is the process of planting by hand or aerial seeding to shore up eroding banks and jump-start plant colonization.

You can read more about CWPPRA Projects that use the vegetative planting restoration technique by clicking here.

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.

Wetland Soils

World Soil Day was officially celebrated on December 5th. This day was created in an effort to share the importance of healthy soil and advocate for the sustainable management of soil resources. Wetland soils, also known as hydric soils, are permanently or seasonally saturated by water and develop anaerobic conditions. Soils’ ability to store surface or ground water and bio-geochemical processes are critical to wetland function and maintaining a healthy ecosystem. Wetland scientists spend a great deal of their time performing soil surveys. Different wetland types feature different soil types. Soils should be evaluated for the presence of pesticides or dangerous elements that could cause damage to the vegetation and animals of that wetland site.

This day was created in an effort to focus on the importance of soil as a critical component of natural systems and as a vital contributor to human well-being.

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Interesting fact:

  • 95% of our food comes from the soil

 

Louisiana’s State Reptile – The American Alligator

The American alligator (Alligator mississippiensis), the largest reptile in North America, is also known as the state reptile of Louisiana. Ancestors of the American alligator appeared nearly 160 million years ago. Alligators are cold-blooded, and their body temperature is regulated by the environment around them. There are approximately 2 million wild alligators in the state of Louisiana. Alligators can be spotted in ponds, lakes, bayous, rivers, swamps, and even occasionally swimming pools near these coastal areas in the dry months. The highest populations of alligators within Louisiana are found in coastal marshes. Coastal marshes account for about 3 million acres of alligator habitat in Louisiana.

Alligators are predators in the wetland ecosystem. Young alligators typically feed on small animals such as crawfish, insects, small fish, and frogs. An adult alligator’s diet consists of crabs, turtles, nutria, large birds, and sometimes deer. Alligators assist in population control and support diversity in the environment.  During nest construction, alligators dig burrows with their tails in peat, a boggy type of soil, which often facilitates plant growth. The burrows become “alligator holes”, or wetland depressions, which serve as a breeding area to many species other than alligators during dry periods. Alligators are key contributors to the diversity and productivity of coastal wetlands.

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