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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World Turtle Day

On May 23, we celebrated the 17th annual World Turtle Day sponsored by American Tortoise Rescue. This nonprofit organization was established in 1990 to protect all species of tortoises and turtles. They created World Turtle Day to serve as an annual observance of protecting tortoises and turtles around the world and their disappearing habitats. Wetlands that serve as habitat for turtles include shallow fresh waters, pelagic salt waters, and heavily and scarcely vegetated areas. Various species of turtles reside in every type of wetland environment.

Did You Know?

  • The majority of turtles that you see on the road are females traveling to their annual nesting sites.
  • Turtles like to eat dead material lying on the bottom of ponds, lakes, and wetlands. Turtles keep the water clean!
  • Snapping turtles rarely snap at humans in water. They do not like the way people smell or taste.
  • If you are helping a turtle cross the road, be sure to move the turtle in the same direction it was originally headed. DO NOT turn it back around! It is likely it will try to cross the road again.
  • If you touch a turtle, it is important that you wash your hands thoroughly. Turtles may carry salmonella.

How to Protect Turtles?

  • Avoid walking or driving on sandy areas where turtles are nesting.
  • Create a “no wake zone” to reduce damage to shoreline wetland habitats and stop the removal of plant materials.
  • Do not remove turtles from their natural habitats.

What Can You Do?

  • You can put signs and small barriers around nesting sites and wetlands that are on your property.
  • You can contact local programs to help pay for habitat restoration in your area.
  • You can add beneficial features to turtle habitat by planting native plants to buffer wetlands and turtle nesting areas. This will attract frogs, snails, insects, and other species that turtles eat.