Matagorda Bay Economic and Ecological Resources Report
Chapter 5. Marsh, Flat and Upland Habitat Resources
Introduction
In this installment of the Matagorda Bay Economic and Ecological Resource Report, we explore the physical and biological characteristics that make marsh, tidal flat and upland habitats ecologically and economically significant components of Matagorda Bay.
In 2019, the Comptroller’s Natural Resources program partnered with Texas A&M University-Corpus Christi (TAMUCC) to conduct the Matagorda Bay Ecosystem Assessment. As part of this comprehensive study, researchers will evaluate the bay's habitats and their contribution to a diverse, healthy ecosystem.
Looking for more information? Check out earlier installments of the resource report to see how researchers are collecting information on key species and their habitats to support ongoing conservation in Matagorda Bay.
Habitats at the Water's Edge
Across earlier chapters, we have explored Matagorda Bay’s submerged habitats. Now at the water’s edge, unique conditions support vibrant low saltmarsh, high saltmarsh, tidal flat and upland habitats.
The Matagorda Bay Ecosystem Assessment’s mapping team, led by Dr. Jim Gibeaut, is compiling high-resolution aerial and satellite imagery and topographic data to map the habitats within two kilometers of Matagorda Bay. The team’s baseline habitat characterization will provide a solid foundation to compare coastal change over time. Resource managers can monitor changes in shorelines and habitats to identify potential impacts on Matagorda Bay’s threatened and endangered species.
Using the animation below, learn a few defining characteristics, like the frequency of seawater inundation, of Matagorda Bay’s fringing habitats.
Flats often are categorized by their formation or main features. Whether they are called mud flats, algal flats or wind-driven tidal flats, these areas are usually recognizable for large patches of mud void of tall vegetation. Many flats are formed as tides deposit fine muds and silts across low-lying areas. Although many appear barren from a distance, these flats host a wide variety of algae, bacteria, invertebrates and the animals that feed on them.
Various bird species forage for worms, crabs, and other invertebrates across tidal flats. Images courtesy of Chelsea Jones.
Coastal marshes are flooded and drained by saltwater. The low saltmarsh contains plants adapted to regular saltwater inundation, including smooth cordgrass (Spartina alterniflora).
Smooth cordgrass roots stabilize the sediment, enabling fiddler crabs to borrow into the soft mud. Burrowing promotes cordgrass health by improving soil drainage, aeration and decomposition. Images courtesy of Rich Kostecke (top) and Chelsea Jones (bottom).
Small gains in elevation are enough to avoid daily tidal and wind-driven changes in water level. In the high saltmarsh, less salt-tolerant plants can outcompete smooth cordgrass. Common grass-like species include marshhay cordgrass, saltgrass and bulbrushes . Forbs and shrubs also occupy these areas.
Diamondback terrapins are uniquely adapted to live in marsh habitats from Texas to New England. These polka-dotted turtles hunt invertebrates and small fish. Image courtesy of Ryan Hagerty (top) and Chelsea Jones (bottom).
Beyond the reach of saltwater, more familiar plant communities thrive. Upland vegetation includes coastal prairie grasses and forbs. Oak mottes, or dense clusters of oak trees, are scattered among the prairies.
A crested caracara perches on a fence post. Upland habitats along the Texas coast are frequently utilized for agriculture. Images courtesy of Chelsea Jones.
Coastal Productivity
Matagorda Bay’s high productivity is sustained by the connection between submerged and intertidal habitats. The assessment team is conducting biological sampling across these habitats to study these interactions and evaluate the influence of habitat arrangement on bay function. This study includes a closer look at the productivity of marsh habitats. Assessment researchers are surveying marsh sites to quantify vegetation community structure. The team is monitoring seasonal changes in community composition, plant density and recruitment. The team also is assessing the decomposition of marsh plants to understand when and how much food becomes available to wildlife.
Assessment researchers collect data to evaluate marsh productivity. Images courtesy of BIO-WEST Inc.
The Rice Belt
Geese and ducks rest and forage on fallow rice fields. Image courtesy of Beverly Moseley.
The upland habitats surrounding Matagorda Bay support part of the U.S. Rice Belt. Long-grained rice thrives in the humid prairies stretching from the bay to the Mississippi River. Rice farming is more than 41 times more concentrated along Matagorda Bay than the rest of Texas. More than 39,000 acres of rice were planted in the 2019 and 2020 growing seasons in Matagorda and Jackson Counties. Matagorda and Jackson Counties are among seven major rice-producing counties in Texas, the sixth-largest rice producer in the U.S.
Rice production is largely dependent on market forces and freshwater availability. Although rice production converts native upland habitats into agriculture fields, the crop still supports wildlife, particularly migratory waterfowl. Geese and ducks visit harvested and flooded fields to stock up on seeds, waste grains and insects before they continue their migration.
Coastal Birds
The Texas coast is a critical rest-stop for migratory birds. Each spring and fall, hundreds of species pass through coastal marshes and uplands to prepare for or recover from their long flights. Many migratory species call Matagorda Bay their winter home, feeding along marshes, tidal flats and uplands until it is time to return to their breeding grounds.
Assessment researchers are conducting visual and acoustic bird surveys every season to document bird presence and habitat condition in Matagorda Bay’s marshes. Healthy, diverse bay habitats will help ensure a wide variety of birds, including many rare and migratory species, can thrive on Matagorda Bay’s shores.
Take a closer look at three birds that are protected by the Endangered Species Act (ESA).
Graphics modified from Integration Application Network media library: Tracey Saxby (vegetation, tern, heron, scientist), Sally Bell (rail), Jane Thomas (plover, crane), and Jane Hawkey (scientist).
Black Rail
Black rails forage and nest within the shelter of thick marsh vegetation. Image courtesy of Woody Woodrow.
Under the cover of thick marsh vegetation, secretive rail species hide from predators as well as the researchers seeking to understand their populations. Although rail species are nearly impossible to see, assessment researchers have deployed acoustic recording devices to detect rail calls. Monitoring rail presence over time will contribute to their long-term conservation. In 2020, the smallest rail on the Texas coast, the eastern black rail, was listed as a threatened species under the ESA.
Piping Plover
Piping plovers forage on beaches and flats. Image courtesy of Loraine Minns.
Piping plovers and closely related shorebirds forage for invertebrates along beaches and tidal flats. Undisturbed flats provide reliable hunting grounds when beach conditions are too harsh. The piping plover is listed as a threatened species under the ESA.
Whooping Crane
Whooping cranes overwinter in Texas marshes. Image courtesy of Ryan Hagerty.
The rarest bird in North America is becoming a more frequent visitor around Matagorda Bay. The whooping crane stands five feet tall and easily strides through tall marsh vegetation to hunt blue crab and graze on vegetation. The whooping crane is listed as an endangered species under the ESA.
Ecosystem Services
Marshes, tidal flats and uplands provide numerous ecosystem services to surrounding coastal communities. The list of natural benefits to enjoy along the coast is long: clean air, fresh seafood, beautiful sunsets and more. The protection and preservation of homes, infrastructure and a way of life can have a substantial price tag — up to $23 billion in annual coastal protection services.
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Erosion Control
Saltwater marshes and tidal flats buffer upland habitats from erosion due to daily wave action. Densely packed marsh plants dissipate wave energy, and their roots hold soft sediment in place. Fifteen feet of marsh can absorb 50 percent of incoming wave energy . At high tides, seawater covers tidal flats. These extremely shallow areas help muffle erosive wave energy.
A “ living shoreline ” is a stabilized coastal edge made of plants and other natural elements to control erosion. Rather than replace natural habitats with hard structures like bulkheads, living shorelines leverage the natural resilience of saltmarsh and other habitats. Living shorelines protect sensitive areas and infrastructure while continuing to provide ecosystem services to the coast.
Debris accumulates below an eroded cliff side at Aransas National Wildlife Refuge. Healthy tidal flats and marshes can protect uplands from erosion. Image courtesy of Steve Hillebrand.
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Flood Control
Incoming storm waves are muffled by coastal vegetation, losing height and energy before contacting man-made structures and potentially decreasing property damage by up to 20 percent . Along the Texas coast where recent hurricanes have brought tremendous amounts of rain, coastal habitats can absorb floodwaters and reduce property damage. One acre of coastal habitat may store up to 1.5 million gallons of floodwater .
High water floods the town of South Padre Island. Saltmarsh can help absorb floodwaters before they reach coastal communities. Image courtesy of NOAA.
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Water Filtration
Stormwater runoff gradually flows across marsh, tidal flat and upland habitats to the open bay. Pollutants within the runoff may bind with sediment and settle among the marsh plants. The plants trap and retain the sediment, keeping associated pollutants out of the bay and away from sensitive species.
The Port Aransas wastewater treatment plant discharges treated effluent into the Port Aransas Nature Preserve, creating prime habitat for coastal birds. Image courtesy of Google Earth.
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Carbon Sequestration
The lush vegetation supported by saltmarsh and upland habitats play an important role in addressing climate change. Healthy growing plants remove carbon dioxide from the atmosphere and hold carbon within the sediment. Saltmarshes and mangroves remove carbon from the atmosphere ten times faster than tropical forests.
Marsh vegetation growing along the Colorado River delta captures atmospheric carbon dioxide. Image courtesy of Chelsea Jones.
Nature Tourism
With plentiful open space and wildlife, Matagorda Bay offers numerous opportunities for nature tourists.
Opportunities for nature tourism motivate millions of people to visit or live along the Texas coast. Nature tourism is an umbrella term for dozens of different activities including bird-watching, paddling, hunting, hiking and more. Matagorda Bay’s extensive open spaces and plentiful fish and wildlife make it a prime location for nature tourism and the economic buzz these activities generate.
Matagorda Bay sits in the middle of the Central Flyway, a major migratory route that funnels millions of birds through Texas every spring and fall. Matagorda Bay is a treasure trove for bird-watchers or “birders.” Volunteer birders organize a local effort to contribute to the National Audubon Society’s Christmas Bird Count (CBC), an annual nationwide bird census. Preliminary results for the 2021 CBC place several Matagorda-area counts on the leaderboard. Matagorda County-Mad Island Marsh tallied the most species in Texas and the U.S. for the 14th count in a row with 224 species.
Likewise, Matagorda Bay offers numerous opportunities for duck hunters. The U.S. Fish and Wildlife Service’s 2021 Migratory Bird Hunting Activity and Harvest report tracks waterfowl hunter activity and harvest in the United States. During the 2020-21 season, the report estimates more than 80,000 duck hunters spent a combined total of 8,600 days in the field, harvesting 1.1 million ducks across Texas.
Bird-watchers and duck hunters generate revenue for local communities and state government. According to a recent issue of Fiscal Notes , state tax revenue from the sale of sporting goods like hunting and fishing equipment has exceeded $1 billion over the last ten years. In 2020, statewide hunting license sales generated $46.9 million in state revenue. For local communities, business and tax revenue is generated when birders and hunters stop in town for food, fuel, equipment and accommodations between trips to the field. Like the migratory species they follow, these nature tourists often are short-term visitors. Fortunately, the majority of birders and hunters visit during winter, supporting coastal tourist economies outside of the traditional warm-weather vacation season.
Just over an hour down the coast, the Aransas National Wildlife Refuge manages marshes, wetlands and upland habitats for native coastal wildlife. Each winter, 70,000 to 80,000 nature tourists flock to the refuge to catch a glimpse of the whooping cranes. During this time of year, nearby towns are a hub for whooping crane tourism, guiding bird-watching tours and hosting annual festivals. In 2007, the Rockport Chamber of Commerce estimated that whooping crane-related activities result in annual economic benefits of $6 million to the local economy.
With relatively little investment, Matagorda Bay’s coastal communities can help grow and maintain a reliable source of bird-based tourism income. Events such as the Matagorda Bay BirdFest celebrate Matagorda Bay’s incredible bird diversity and encourage birders to spend time in town. Visitors can enjoy numerous access points to the natural wonders of Matagorda Bay. The Texas Parks and Wildlife Department (TPWD) maintains the Great Texas Coastal Birding Trail , including over 20 points of interest that draw tourists to the region. To view resident and migratory birds up close, paddlers can meander along TPWD’s Port O’Connor Paddling Trail to explore the bay’s marshes and view wildlife.
Coastal Change
Marshes, tidal flats and uplands are particularly vulnerable to sea level rise. Low elevation and gentle slopes enable rising water levels to travel great distances inland. While saltmarshes are well-adapted to the water-land margins, their long-term success depends on ample space and sediment to migrate with the shifting waterline. If rising water levels outpace marsh migration or the habitat gets pinned between water and hard infrastructure, the marsh will drown.
Tidal flats have a more complex future in the face of sea level rise. Present-day flats may gradually become submerged by rising sea levels. On the other hand, increased inundation in low-lying areas may clear vegetation and develop new tidal flats.
Although upland habitats are less likely to become regularly submerged, retreating coastal habitats may enable storm surge to advance further inland. Sea level rise can lead to an increase in property damage and upland habitat degradation.
Mapping the Delta
The Colorado River is the largest tributary of Matagorda Bay, transporting freshwater and sediment from the Hill Country and coastal plains to the bay. Today, the delta where the Colorado River empties water and sediment into Matagorda Bay is rapidly building new marsh habitat for fish and wildlife.
This version of the delta is relatively new. In the late 1800s, a massive log jam clogged dozens of miles of waterway, choking the bay’s main source of freshwater and sediment. When the jam was cleared in 1929, the new influx of sediment established marshes and sandy shoals far into the bay. These new shallows disrupted boat traffic and subjected the community of Matagorda to severe flooding. Five years later, a channel was dredged to usher river water and sediment to the Gulf of Mexico. Throughout the 1990s, a series of cuts and plugs were installed to reinvigorate the bay ecosystem and create the modern-day delta.
Use the slider to compare the change in the Colorado River Delta between 1985 and 2018. Images courtesy of Google Earth.
Conclusion
Marsh, tidal flat and upland habitats make unique and valuable contributions to the health of Matagorda Bay’s wildlife and coastal communities. Numerous ecosystem services support people and infrastructure, as well as the diverse fish and wildlife that draw many nature tourists to the coast.
The Matagorda Bay Ecosystem Assessment team is collecting data across all the bay’s habitats to understand the productivity and health of the overall system. More information on Matagorda Bay’s marsh, tidal flat and upland habitats can provide additional insight into the value and vulnerabilities of these habitats. The long-term conservation of these habitats can support more robust populations of coastal threatened and endangered wildlife and resilient coastal communities.
