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 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

Wetland Wonders at Ocean Commotion

Can you figure out the mystery coastal item based on the following clues? It contains a bivalve that a) makes pearls, b) is a filter feeder, and c) we eat here in Louisiana.

Over 1600 elementary and middle school students had the chance to read those clues at LSU Sea Grant’s Ocean Commotion on October 24 in Baton Rouge. Students, teachers, and chaperones then reached their hands into a box and tried to identify the item (oyster shell) they were holding. Other mystery items included a nutria pelt, cypress knees, an apple snail shell, and a magnolia seed pod- all from plants and animals that call Louisiana’s coastal wetlands home.

2017 marks the 20th Anniversary of Ocean Commotion, an annual event meant to give students the chance to get up close and personal with coastal and sea life and the challenges facing those environments. This year 70 exhibitors taught students about topics as diverse as boating safety, mosquito control, and microplastics. CWPPRA outreach staff talked with students about the diversity of species found in Louisiana’s wetlands and the challenges of invasive species, giving students an opportunity to think about how different species impact ecosystems in different ways.

 

Coastal Day at the Louisiana Legislature

On Tuesday, May 2, 2017, the Coastal Wetlands Planning, Protection, and Restoration Act’s Public Outreach staff participated in the annual Coastal Day at the Louisiana Legislature. This event, organized by the Coast Builders Coalition, aims to educate legislators about the tremendous effort being made to protect and restore Louisiana’s coast.  Coastal Day is a key moment to communicate with and educate representatives and legislators from across the state about the value of protection and restoration of Louisiana’s coast.

The CWPPRA outreach team shared a number of publications at Coastal Day containing information regarding what CWPPRA is, the effectiveness of its projects, and the future of coastal Louisiana. In addition to distributing information and answering questions regarding CWPPRA’s completed, active, and future projects, the outreach staff attended a meeting in which Governor John Bel Edwards spoke highly of restoration efforts in Louisiana and the importance of the 2017 Coastal Master Plan. He also recognized the value of wetlands to both the state and the country, declaring his enthusiasm to move forward with the opportunity to resolve the coastal crisis and become more adept at water management. In addition to the governor, speakers including Representative Jerome Zeringue, Senator Dan Morrish, Johnny Bradberry with CPRA, and Scott Kirkpatrick with Coast Builders Coalition discussed issues affecting Louisiana’s coast. Steve Cochran with Restore the Mississippi River Delta and the Environmental Defense Fund discussed a recent poll in which a resounding 97 percent of voters agreed that Louisiana’s coastal wetlands are important to them.

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