Stress Part II: Flooding and Hypoxia

Wetland inhabitants must also deal with flooding stress. All parts of a plant must have oxygen, which causes problems when a plant is rooted in hypoxic soils and it is flooded. Gases diffuse about 10,000 times more slowly through water than through air, and wetland soils are often inundated and hypoxic. This poses an issue for supplying roots with enough oxygen since they don’t have any around them. Some root systems will have adventitious roots, which means they extend above the surface of the water or soil to allow gas exchange with the atmosphere.[1] Red mangroves have prop roots, black mangroves have pneumatophores, and both supply oxygen directly to the root system rather than relying on transport all the way from the leaves to the roots.[2]

Hypoxia can be caused by eutrophication and decomposition. Hypoxia and anoxia are dangerous to most plants and animals because most cannot live only with anaerobic (without oxygen) respiration. Bacteria can sometimes live in anoxic conditions by using different electron receptors that are more plentiful in wetland soils like sulfates. Plants can sometimes cope with hypoxia thanks to adaptations like aerenchyma development in their roots. Aerenchymous tissues are much more porous to allow gases to diffuse up to 30 times more easily through a plant! In animals, lungs can allow some fish, mammals, and aquatic gastropods (snails) to live in hypoxic waters, but many fish have gills that are not adapted to hypoxia. The Gulf of Mexico along Louisiana’s coast boasts one of the largest hypoxic zones in the world with a peak area of over 8,500 square miles in 2017, where many commercial fisheries have seen a large decline in fish catch. [3]

PHOTO- dead zone map-NOAA-700x345-Landscape
Photo from NOAA, Dead Zone 2017

Works Cited:

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

[2] “Adaptations.” Adaptations :: Florida Museum of Natural History, http://www.floridamuseum.ufl.edu/southflorida/habitats/mangroves/adaptations/.

[3] “Gulf of Mexico ‘Dead Zone’ Is the Largest Ever Measured.” Gulf of Mexico ‘Dead Zone’ Is the Largest Ever Measured | National Oceanic and Atmospheric Administration, web.archive.org/web/20170802173757/http:/www.noaa.gov/media-release/gulf-of-mexico-dead-zone-is-largest-ever-measured.

Featured image is of Rhizophora mangle (red mangrove) from Flickr by barloventomagico

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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.

Avicennia_germinans-salt_excretion
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

Audubon Zoo – Earth Fest

Environmental awareness is an important factor in protecting the earth, and the Audubon Institute understands that. With the help of Entergy, the Audubon Zoo has hosted Earth Fest for over twenty years to date, celebrating conservation and environment-friendly practices.

This past Saturday, March 24, CWPPRA was one of many organizations to be represented at Earth Fest along with Wetland Watchers, EnergySmart, Sea Grant, and many more. Each of these organizations brought educational activities to be enjoyed by children and adults alike, such as demonstrations of energy-saving appliances, composting, and beekeeping strategies. Participants could paint with produce from a local farmer’s market, learn about the similarities in bone structures between humans and manatees, and get their faces painted. When they were not busy visiting the zoo enclosures or talking to organizations, guests could enjoy a number of local food vendors or live performers at the pavilion, including Grammy-winning Lost Bayou Ramblers from south Louisiana.

CWPPRA Public Outreach spent the day handing out informational booklets about restoration projects, posters from the Protect Our Coast series, and activity books, as well as playing our popular “Wetland Jeopardy” game with any and all who were interested. Many eager and interested visitors participated in the Earth Fest Earth Quest, a game that led them to ask questions to appropriate organizations in exchange for a stamp. 10 stamps earned them a prize of a young plant to take home and care for. Earth Fest had a wide range of attractions that hopefully inspired all visitors to be more conscious of environmental issues and to help in the efforts to live for a healthier tomorrow.

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New Orleans Landbridge Shoreline Stabilization & Marsh Creation (PO-169)

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Since 1956, approximately 110 acres of marsh has been lost along
the east shore of Lake Pontchartrain between Hospital Road and
the Greens Ditch. One of the greatest influences of marsh loss in
the area can be attributed to tropical storm impacts. Wetland losses
were accelerated by winds and storm surge caused by Hurricane
Katrina, which converted approximately 70 acres of interior marsh
to open water. Stabilizing the shoreline and protecting the
remaining marsh would protect natural coastal resources dependent
on this important estuarine lake, communities that thrive on those
resources, the Fort Pike State Historical Site, and infrastructure
including U.S. Highway 90. USGS land change analysis
determined a loss rate of -0.35% per year for the 1984 -2011
period of analysis. Subsidence in this unit is relatively low and is
estimated at 0-1foot/century (Coast 2050).

Lake Pontchartrain supports a large number of wintering
waterfowl. Various gulls, terns, herons, egrets, and rails can be
found using habitats associated with Lake Pontchartrain, which has
been designated as an Important Bird Area by the American Bird
Conservancy. Restoring these marshes will protect the Orleans
Landbridge and will help to protect fish and wildlife trust resources
dependent on these marsh habitats, particularly at-risk species and
species of conservation concern such as the black rail, reddish
egret, brown pelican, mottled duck, seaside sparrow, king rail, and
the Louisiana eyed silkmoth.

Borrow material will be dredged from areas within Lakes St.
Catherine and Pontchartrain to create 169 acres and nourish 102
acres of brackish marsh. Containment dikes will be constructed
around four marsh creation areas to retain sediment during
pumping. The lake shorelines will be enhanced with an earthen
berm to add additional protection from wind induced wave fetch.
Containment dikes that are not functioning as shoreline
enhancement will be degraded and/or gapped. Vegetative plantings are
proposed including five rows along the crown and two rows
along the front slope of the shoreline protection berm, as well as
within the marsh platform area.

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The project is located in Region 1, Pontchartrain Basin,
Orleans Parish, flanking U.S. Highway 90 along the east shore of
Lake Pontchartrain and areas surrounding Lake St. Catherine.

This project was approved for Phase I Engineering and Design in
January 2015.

This project is on Priority Project List (PPL) 24.

The New Orleans Landbridge Shoreline Stabilization & Marsh Creation sponsors include:

 

 

Bayou Dupont Sediment Delivery – Marsh Creation and Terracing

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Wetlands in the Barataria Basin were historically nourished
by the fresh water, sediment and nutrients delivered by
the Mississippi River and its many distributary channels.
These sediment and nutrient inputs ceased following the
creation of levees along the lower river for flood control and
navigation. In addition, the construction of numerous oil and
gas canals along with subsurface oil and gas withdrawal has
exacerbated wetland loss in the area. From 1932 to 1990, the
Barataria Basin lost over 245,000 acres of marsh. From 1978
to 1990, the area experienced the highest rate of wetland loss
in coastal Louisiana.

The primary goal of this project is to create and nourish
approximately 144 acres of emergent intermediate marsh
using sediment from the Mississippi River, and constructing
9,679 linear feet of terraces. The proposed project includes
dredging sediment from the Mississippi River for marsh
creation by pumping the sediment via pipeline into an area of
open water and broken marsh. The proximity of the project
to the Mississippi River provides a prime opportunity to
utilize this renewable river sediment resource. The strategy
includes utilizing the access route and infrastructure
previously put into place for the BA-39 project. This project
will complement existing restoration projects in the area.

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CWPPRA Region 2, Barataria Basin, Jefferson and
Plaquemines Parishes. The general project area is about 10
miles south of Belle Chasse, LA and is west of LA Hwy
23 and north of the Myrtle Grove Marina. The project
is immediately adjacent to the completed CWPPRA
Mississippi River Sediment Delivery System – Bayou
Dupont (BA-39) project.

The project was approved for engineering and design at the
January 24, 2013 Task Force meeting. The E&D was
completed in the fall of 2014 and sponsors requested phase
2 funding at the January 22, 2015 Task Force meeting,
however, there was insufficient money available to fund
the entire project. In order to take advantage of the existing
mobilization of the Long Distance Sediment Pipeline
(LDSP) Project, the sponsors proposed to reduce the scope
of the project to fit within the available CWPPRA funding.
The Task Force approved the reduced scope Phase 2 funding
request at the May 14, 2015, Task Force meeting. The asbuilt
project features include 144 acres of marsh creation and
9,679 linear feet of terracing.

In addition, CPRA increased the marsh creation feature of
the project by utilizing contingency funding left over from
BA-43, thereby increasing the total marsh creation in the
area to an estimated 296 acres. Construction started in April
2016, and marsh creation was completed in November
2016. Terracing was completed in June 2017, and vegetative
plantings for the terraces are scheduled for the spring of
2018.

This project is on Priority Project List (PPL) 22.

The Bayou Dupont Sediment Delivery – Marsh Creation and Terracing sponsors include:

 

Wetlands and Waterfowl

At this time of year in Louisiana, you are sure to see early morning waterfowl hunters dressed in their best camouflage. Louisiana sits on the Mississippi Flyway, North America’s most heavily-used migration corridor for waterfowl. Louisiana’s coastal wetlands provide habitat for more than five million migratory waterfowl, approximately half of the wintering duck population of the Mississippi Flyway. The coastal marshes of Louisiana provide habitat to mottled ducks, wood ducks, redheads, and pintails, just to name a few species. These waterfowl species can be spotted in coastal marshes, flooded timbers, flooded grain fields, and other wetland areas. Grab your waders, shot gun, and a duck call, and take advantage of Louisiana’s Sportsman’s Paradise.

pintail duck wood duck mottled duck

It is critical to protect the coastal marshes and wetlands within the state for Louisiana to remain the front runner for waterfowl hunting. CWPPRA projects are aimed at protecting and restoring Louisiana’s coastal wetlands, ensuring that wildlife and the people who hunt them have the habitat they need.

America Recycles Day

     Today we celebrate America Recycles Day: a national initiative of Keep America Beautiful. Recycling offers numerous benefits to both our environment and human health. Recycling is one of the best actions you can take to protect natural resources. Plastics being discarded in animal habitats continue to pose a serious threat to the health of wildlife that occupies the area. Many animals die each year from ingestion of these hazardous materials, and researchers in Ireland found that plastic bags littering wetlands could smother wildlife and algae underneath [Green et al., Environ. Sci. Tech., 2015, 49 (9), pp. 5380-5389]. Along with providing a healthier habitat for animals to live, recycling beautifies the area humans utilize for recreational purposes. You can help save our wetlands and other natural habitats by picking up litter and disposing of the unwanted materials in the appropriate recycling bins or at recycling centers.

     Visit the America Recycles Day website to find valuable information on what materials can be recycled, where they can be recycled, and how they can be recycled. The recycling locator is a useful tool the website provides for finding locations to recycle in your community. While you’re visiting the America Recycle Day website, you can also take the #BeRecycled Pledge to learn, act and share with others the power of recycling.

America Recycles Day