Coastal Marshes



Marshes rim the upper Texas coast, and provide a transition between prairies and bays.

A salt marsh lines the salty water of the bay. It’s a muddy, mucky place with changing salinity, temperature and water levels. It’s dominated by Spartina alterniflora, which hides small shell- and finfish.

A brackish, or intermediate, marsh is characterized by plants that tolerate both salt and fresh water conditions due to occasional strong storm surges that flood inland areas with salt water. As the climate changes and sea levels rise, there is concern for the viability of these marshes due to a continuous presence of saltwater.

Freshwater marshes are adjacent to prairies, and cannot support saltwater intrusion. These are common near Sabine Lake by Port Arthur. They require large amounts of rainfall runoff to maintain low salinity. This habitat is severely affected by drainage alterations upstream.

Here’s more information about the difference between a wetland, marsh and swamp.

The best way to see a marsh is by kayak, due to the sticky mud. Contact Artist Boat for an educational trip.


Courtesy of Texas Coastal Exchange:

Coastal marshes act as protective barriers for inland areas against the storm surges of strong storms by absorbing wave energy. They capture floodwaters and release them slowly, lessening the impact of floods. Vegetation protects against erosion by stabilizing sediments and lessening the power of wave action. It provides habitat for birds, shellfish and juvenile finfish and acts as a nursery for bay organisms. Plants filter out excess nutrients, like nitrogen and phosphorus, pollutants and pathogens. They are also a carbon SINK because they remove carbon dioxide (called blue carbon) from the atmosphere and store it in their roots and wood, as well as the soil. This rich, organic soil holds an enormous amount of water and stimulates plant growth, creating a positive feedback loop.

HoustonUrbanTNC · Clive Runnels Mad Island Marsh Preserve - December 2019


Blue carbon is any carbon stored in coastal and marine ecosystems, in both plants and sediment. Coastal habitat accounts for half of the total carbon sequestered in ocean sediment, and oceans cycle about 80% of the global carbon. Projects are being developed all along the Texas coast to protect and restore coastal habitat to offset carbon emissions.

Teaching tip: Calculate your Carbon footprint using various online tools, and find ways to reduce the footprint of your school.

Teaching tip: Participate in Galveston Bay Foundation’s Hip to Habitat program.


Alligators galore! Once an endangered species, these cold-blooded creatures rebounded nicely when hunting and trapping seasons were closed. Brazos Bend State Park’s website has many alligator resources for the curious.

Teaching tip: Contact Crocs in the Classroom to care for little crocodiles.

Historically, the marshes were full of otters (Lutra canadensis) and muskrats (Ondatra zibethicus), but they are far less common today. Muskrats eat cattails, an abundant plant. Garter snakes are excellent swimmers, and make a great snack for Great Blue Herron or Great egrets. Many of the birds are protected by federal and state laws; Texas Parks and Wildlife differentiates between wild and game birds.

A pesky invasive is the nutria (Mycocastor coypus). Originally from South America, nutria were introduced by fur traders and by people using them to control vegetation.