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.

 

 

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Sabine Refuge Marsh Creation Cycle III

CS-28-3-01

The project area is experiencing marsh degradation due to
saltwater intrusion and freshwater loss. This has resulted
in the conversion of vegetated intermediate marsh to
large shallow open water areas. Salinity migrates into the
region from the Calcasieu River. Southerly winds push
saline waters into the project area through existing canals
and bayous. Wind driven waves cause further loss of the
remaining marsh fringe.

Cycle III consists of the creation of 232 acres of marsh
platform using material dredged from the Calcasieu River
Ship Channel. Between February 12 and March 31, 2007,
828,767 cubic yards of dredged sediment material was
placed into the Sabine Refuge Cycle III marsh creation area.
The dredged material is contained by earthen dikes. Lower
level earthen overflow weirs were constructed to assist in the
dewatering of the marsh creation disposal area and to create
fringe marsh with the overflow. The dredged slurry has been
placed between elevations 2.03 NAVD 88 to 2.71 NAVD 88.

map

This project is located in the Sabine National Wildlife
Refuge, west of LA Highway 27, in large, open water areas
west of Brown’s Lake in Cameron Parish, Louisiana.

The Sabine Refuge Marsh Creation Project was originally
approved as part of the Project Priority List 8 in 1999. The
project was later broken into 5 cycles. In 2004, additional
funds for engineering and design and construction were
approved for Cycle III. The placement of the dredged
material has been completed. Degradation of the retention
dikes is ongoing and expected to be completed soon.

This project is on Priority Project List (PPL) 8.

The Sabine Refuge Marsh Creation Cycle III’s sponsors include:

Sabine Refuge Marsh Creation Cycle II

CS-28-2-01

The project area is experiencing marsh degradation due to
saltwater intrusion and freshwater loss. This has resulted
in the conversion of vegetated intermediate marsh to large
shallow open water areas. Salinity migrates into the region
from the Calcasieu River. Southeast winds push saline
waters into the project area through canals and bayous.
Wind driven waves cause further loss of the remaining marsh
fringe.

A permanent dredged material disposal pipeline, measuring
3.57 miles in length, will be constructed in Cycle II. The
pipeline will commence near Mile 13.2 of the Calcasieu
River Ship Channel and terminate at the northeastern corner
of the Sabine National Wildlife Refuge. Much of the right
of way required for the pipeline was previously impacted
by the construction of a temporary pipeline used during the
construction of Cycle I. The pipeline is to be used for future
marsh creation projects in conjunction with the U.S. Army
Corps of Engineers maintenance dredging of the Calcasieu
River Ship Channel.

map

The project is located on the
Sabine National Wildlife Refuge, west of Highway 27, in
large open water areas northeast of Brown’s Lake.

The Sabine Refuge Marsh Creation Project was originally
approved as part of the Project Priority List 8 in 1999. The
project was later broken into 5 cycles. In 2004, additional
funds for engineering and design and construction were
approved for Cycle II. The pipeline is constructed and will
be available for use during the 2011 maintenance dredging of
the Calcasieu River Ship Channel.

This project is on Priority Project List 8.

The Sabine Refuge Marsh Creation Cycle II’s sponsors include:

Invasive Species

Wetlands provide storm surge protection, water filtration, and habitat for plants and animals. Our coastal communities also receive many other benefits from wetlands. Unfortunately, our wetlands have become vulnerable to invasive species. An invasive species is defined as any species not native to the ecosystem which is likely to cause environmental harm. Invasive species, both plants and animals, pose a huge threat to maintaining a healthy coastal environment. These non-native species tend to compete with the native species, ultimately displacing them. Predator-prey relationships can be detrimentally affected, altering the way wetland ecosystems function and deteriorating their value. Invasive species also contribute to coastal habitat loss which greatly affects the state of Louisiana.

Apple snails are an invasive species that destroy fish habitat by consuming vegetation and leaving the water dominated by algae. These snails are hosts for parasites which can be spread to small mammals and humans. Giant salvinia (Salvinia molesta) is a hostile form of vegetation that grows at a rapid rate. The thick invasive plant species can obstruct waterways and block sunlight and air from our native vegetation, killing the foundation of the food chain. Nutria, a medium-sized rodent, is known to destroy marshlands that provide protection from flooding and are habitats for birds, fish, and other animals. A nutria control program was initiated in Louisiana in 2002 by the Louisiana Department of Wildlife and Fisheries to achieve the public’s help in suppressing this invasive threat. Monetary rewards are given for each nutria pelt that is turned in to one of the program’s collection stations.

invasive-snails-9128bceaf00ade6e nutria2_502672_7

While eliminating most invasive species is nearly impossible, a degree of control is the goal. CWPPRA works to protect the wetlands by developing strategies to lessen the threat of invasive species. You can read Watermarks #56 Halting Invasive Species’ Assault on the Wetlands to learn more about this topic.

Sabine Refuge Marsh Creation Cycle I

CS-28-1-01

The project is intended to strategically create marsh in large,
open water areas to block wind-induced saltwater
introduction and freshwater loss. In addition, it will increase
nourishment in adjacent marshes while reducing open water
fetch (distance a wave can travel) and the erosion of marsh
fringe.

Cycle I constructed 214 acres of marsh within the shallow,
open water area within retention dikes. The perimeter of the
created marsh was planted with smooth cordgrass. Dredged
slurry obtained from the Army Corps of Engineers’ dredging
of the Calcasieu River Ship Channel was placed in the
containment area.

Upon consolidation of the dredged material, the southern
containment dike was degraded and breached to allow for
water movement and restore the area to more natural
conditions. Prior to the placement of dredged material,
trenasses (small, man-made bayous) were constructed in the
project area. These trenasses facilitate natural conditions and
allow estuarine organisms to access the created marsh. This
project is part of five cycles over a 10-year period with each
cycle requiring individual construction approval.

map.jpg

The Sabine Refuge Marsh Creation Project is located in the
Sabine National Wildlife Refuge, west of LA Highway 27, in
large, open water areas north and northwest of Brown’s Lake
in Cameron Parish, Louisiana.

Priority Project List 8 funded $5.9 million to complete
construction of a permanent pipeline and one cycle of marsh
creation. Engineering analyses at the time indicated that the
construction of a temporary pipeline would be more cost
effective. Therefore, a temporary pipeline was utilized for
Cycle I. However, further analysis determined that a
permanent pipeline would be advantageous. In 2004,
additional funds for engineering and design and construction
were approved for Cycles II and III. Funds for Cycle II
include the construction of a permanent dredged material
pipeline.

Construction of the Cycle I site was completed on February
26, 2002.

This project is on Priority Project List (PPL) 8.

The Sabine Refuge Marsh Creation Cycle I’s three sponsors include:

View more data on the CS-28-1 project or other projects on CWPPRA’s website.

Giant Salvinia

Giant Salvinia, or Salvinia adnata, often referred to as the green monster, poses a serious threat to wetland ecosystems. This highly invasive, aquatic plant species is native to Brazil. The floating aquatic fern has leaves covered with small hairs on the upper surface that become compressed into chains forming a dense, compiled mat-like structure. In the United States, it’s difficult to control Giant Salvinia due to the lack of legal herbicides that work efficiently to stop it from spreading. Giant Salvinia was first spotted in Chenier Plain Marshes in 2009; since then it has spread throughout.

This non-native plant species has an exceedingly rapid growth rate, and under the right conditions it can potentially take over a waterway causing catastrophic results. The mat blocks sunlight from penetrating into the water, ultimately killing phytoplankton and other aquatic plant species, as well as exhausting oxygen levels, which alters the area as a waterfowl habitat and degrades the water quality for fish. Giant Salvinia is unintentionally spread to new water bodies on boats and fishing gear. One way to prevent the expansion of Giant Salvinia is to properly clean boating equipment and vessels of any plant fragments. These plant fragments, garden, and aquarium plants should all be discarded properly in the trash and kept out of water bodies. It is important to properly control and dispose of the plant material in order to keep lakes, rivers, ponds and other freshwater wetlands functioning properly without the disturbance caused by Giant Salvinia.

Cyrtobagous salviniae, a species of weevil, is often referred to as the salvinia weevil due to being a biological pest control against the highly invasive Giant Salvinia. For more information on Giant Salvinia and CWPPRA’s efforts to control this invasive plant species visit the Coastwide Salvinia Weevil Propagation Facility (LA-284) Fact Sheet.

Classification of Marshes

Marsh is a type of wetland that is continually flooded with water. Marshes can be found both on the coast or inland. Most of the water present is due to surface water; however, some groundwater also fills this wetland area.

Marshes can be divided into two main categories: non-tidal and tidal.

Non-tidal Marshes:

  • Most widely distributed and productive wetlands in North America
  • Occur along the boundaries of lakes, streams, rivers and ponds
  • Mostly freshwater, but some are brackish or alkaline
  • Beneath these wetlands lie highly organic soils
  • You might spot cattails, lily pads, reeds, and an array of waterfowl in this wetland
  • Alleviate flood damage and filter surface runoff

Tidal Marshes:

  • Found along protected coastlines and impacted by ocean tides
  • Present along the Gulf of Mexico
  • Some are freshwater or brackish, mostly saline
  • Provide shelter and nesting sites for migratory fowl
  • Covered by smooth cordgrass, spike grass, and salt meadow rush
  • Slow down shoreline erosion

watershed_illustration-large