Upper Coast Estuaries and Freshwater Runoff and Whoopers on the Texas Chenier Plain
Article by Nate Skinner
Photos by Tosh Brown, Larry Ditto, Chase Fountain/TPWD, Craig Korczysnki, David Sikes, Nate Skinner
It has been said that freshwater is the lifeblood of an estuary. No truer a statement could be made about our upper Texas coast bays and their surrounding marshes.
From the Galveston Bay complex to Sabine Lake, and everywhere in between, rivers, bayous and watersheds regularly provide freshwater and nutrients to estuarine systems. Some of the major freshwater inflow sources along the upper coast include the San Jacinto River, Trinity River, Neches River and Sabine River watersheds. These freshwater inflows help to balance salinities, keeping marshes healthy and bay ecosystems productive.
Floods and droughts affect how freshwater inflows affect upper coast bays as do resource users such as land managers and others located along these upstream watersheds. With that said, each estuary functions under its own unique set of dynamics. Therefore, fishery and wildlife managers, as well as all resource users, must be mindful of how their bay system reacts to changes in the natural, downstream flow of freshwater.
Sabine Lake is by far the freshest bay along the Texas coast due to the significant freshwater inflows it receives from both the Neches and Sabine rivers. The nutrient input from these rivers into Sabine Lake contributes to the growth of primary producers.
“This is what makes Sabine Lake such a productive estuary,” said Dr. Carey Gelpi, Texas Parks and Wildlife Department Sabine Lake Ecosystem Leader. “Freshwater inflows are the backbone of the ecosystem.”
Gelpi said that too much freshwater flowing into Sabine Lake due to flooding events could lower salinities enough to cause a redistribution of species across the estuary.
“Speckled trout are a good example of this,” he said. “The north end of the lake is the first place that the estuary receives freshwater from rivers, so we will typically see speckled trout concentrate towards the lower end of lake, as well as in Sabine Pass, when salinities begin to fall drastically.”
Gelpi said that freshwater inflows have also played a role in the distribution of oysters in Sabine Lake over time.
“The ideal salinity range for oysters to thrive is 10-15 ppt,” said Gelpi. “Back in the 1800s, the estuary’s main concentration of oysters was located in Sabine Pass, about five miles south of where they are today, because that’s where their preferred salinity dynamic was oriented. Sabine Lake was much fresher at that time, because the channel leading from the pass into the lake was significantly shallower, allowing for less exchange between estuarine and Gulf waters.”
Gelpi said that the present concentration of live oysters lies along a significant reef located in the southwestern region of Sabine Lake, north of the Sabine Pass causeway. Even though large areas of the lake can have salinities as low as 2-3 ppt for months on end, he said that oysters are thriving in this portion of the estuary.
“Oyster restoration projects, as a result of collaborative efforts from TPWD, Coastal Conservation Association and other partners, have significantly enhanced the health and future of our oysters in recent years,” Gelpi said. “We haven’t seen a large-scale die-off of oysters in the past five years, and we expect oysters to continue to grow and expand in the foreseeable future because of these projects. This is extremely important for the future of our fishery, as oyster reefs play a key habitat component for a variety of species of fish, crustaceans and other aquatic organisms.”
In 2015, oyster cultch, the foundation of an oyster bed, in the form of river rock was deployed near a historical, existing oyster reef in the southwestern portion of Sabine Lake as a part of an oyster habitat expansion project. This deployment included 1,750 mounds of river rock, measuring four cubic yards by volume that were spaced 20 feet apart from center to center. According to Gelpi, new oysters have already begun to grow and consolidate on this material.
This summer, a new project took place to further enhance these oyster restoration efforts. This expansion project included 3,706 cubic yards of oyster cultch in the form of limestone, which produced 926 new mounds that were placed strategically in relation to the existing material.
“Spacing for the mounds on the latest project was set at 25 feet on center,” said Gelpi. “Each mound consisted of four cubic yards of cultch, and they were deployed in a manner in which they would be structured about two feet in height.”
As of early June 2020, the project was scheduled to be completed by the end of July. Funding for the project was provided by the CCA Building Conservation Trust and Harvey Fisheries Disaster Relief funds.
CCA Assistant Director and Director of Habitat John Blaha said that the recent project’s goal was adding a bunch of small patch reefs near natural, existing oyster reefs.
“The structure and spacing of the mounds help to create a more diverse habitat along the bay bottom,” he said.
CCA Advocacy Director Shane Bonnot said that historically, most oyster cultch has been deployed in a manner in which it was sheeted, or spread out evenly and flat, across the bay floor.
“TPWD and CCA both agree that the mounding technique utilized in the project mimics the structure of a more natural oyster reef,” said Bonnot. “The mounds were all placed within a rock’s throw of each other. This checkerboard design will promote tremendous expansion of the existing reef in the southwestern portion of Sabine Lake.”
The Galveston Bay Complex represents the state’s largest estuary, and it is much saltier than Sabine Lake. The San Jacinto and Trinity rivers, along with many secondary bayous and creeks, help to regulate the salinity within the system by bringing freshwater from upstream watersheds. TPWD Galveston Bay Ecosystem Leader, Christine Jensen, said that like Sabine Lake, these freshwater inflows are important for the complex’s many oyster reefs.
“Oysters are a key habitat feature along the bottom of the Galveston Bay Complex,” said Jensen. “They filter the water and help minimize erosion over time. Many different types of fish, shrimp, crabs, other crustaceans and a variety of aquatic species also rely on oyster reefs to survive and thrive.”
The right balance of fresh and saltwater is necessary for Galveston Bay’s oysters to flourish. Jensen said that drought conditions can significantly reduce the amount of freshwater that the complex receives, which in turn is not good for its oysters.
“High salinities leave oysters susceptible to damage or mortality from marine predators like the oyster drill or sponges, both of which thrive in the salty waters of the Gulf,” said Jensen. “These predators will sometimes enter the estuary as salinities rise.”
Jensen said that high salinities also threaten oysters with the increased risk of disease, particularly one classified as Dermo, which is caused by a parasite that thrives in salinities above 12-15ppt.
As far as flooding events are concerned, oyster mortality can occur if significant freshwater inflows keep salinities low for long periods of time.
“Oysters can handle salinities as low as 5-7 ppt for about two weeks during the summer months,” Jensen said. “After that, they will begin to die off if salinities do not rise. During the wintertime, they can withstand low salinities for a little bit longer, because their metabolic rate is lower due to the cooler water temperatures associated with that time of the year.”
Galveston Bay oysters had a significant die-off due to a prolonged period of low salinities as a result of the flooding rains from Hurricane Harvey back in 2017. Jensen said that East Galveston Bay experienced the largest oyster loss, with mortality rates as high as 50-90 percent in some areas.
Unlike Sabine Lake, the Galveston Bay Complex supports a commercial oyster fishery. Jensen said that the estuary currently accounts for as much as 45 percent of the entire state’s commercial landings of oysters each year.
In 2017, the Texas State Legislature passed House Bill 51. The bill requires entities and purchasers within the commercial oyster industry to replant oyster cultch amounting to 30 percent of the total amount of oysters they purchased by volume during the previous license year into areas approved by TPWD. This can be in the form of oyster shells, or other TPWD approved oyster cultch material.
These commercial entities can also choose to pay TPWD a fee to replant the material instead of replanting it themselves. This fee is calculated by multiplying the market cost by 30 percent of the volume of oysters that the entity or individual purchased during the previous license year.
“House Bill 51 has definitely helped improve the future of oysters in Galveston Bay, as the replanting of oyster cultch back into the system is extremely important,” said Jensen.
Jensen said that TPWD is currently working with its partners to obtain permits for future oyster restoration projects within the Galveston Bay Complex.
Texas Chenier Plain
The Chenier Plain in Texas represents an integral and key component of the upper Texas coast. Stretching from the eastern portion of the Galveston Bay Complex and its surrounding marshes to the marshes and wetlands lining the western perimeter of Sabine Lake, this key ecoregion encompasses beaches and marsh ecosystems that are extremely important to our upper coast fisheries as well as all species of wildlife that inhabit it.
The landscape feature also plays a key role as a storm buffer for the communities that lie within the region, and the Army Corps of Engineers estimates that for every 2.7 miles of emergent marsh, one foot of storm surge can be reduced. Unfortunately, the Chenier Plain had been withering away, as it has incurred significant beach and marsh loss in passing decades.
The area has suffered from a lack of natural freshwater inflows which serve to keep its marshes in a healthy state. This is due in part to land development that rendered significant changes on the landscape, altering the natural downstream flow of fresh water.
In recent years, government agencies, stakeholders and organizations have combined efforts to oversee projects to restore the Texas Chenier Plain back to a healthier and more productive state. These projects include marsh restoration, beach and sand dune restoration, restoring the presence of natural freshwater inflows, and efforts to minimize saltwater intrusion into marsh areas that have historically held consistently low to moderate salinities. Most of the efforts have been concentrated around the Salt Bayou watershed.
The projects’ results are benefitting a suite of estuarine species and other wildlife across the Texas Chenier Plain, which also includes the JD Murphree Wildlife Management Area, as well as the McFaddin, Anahuac, Texas Point, and Moody National Wildlife Refuges. Some of the key players overseeing these projects include TPWD, the U.S. Fish and Wildlife Service, Ducks Unlimited and Jefferson County Judge Jeff Branick along with other agencies and partners.
According to the Texas Chenier Plain National Wildlife Refuge Complex Manager Tim Cooper, the development of a clay berm built inland of McFaddin Beach was the initial step in preventing Gulf seawater intrusion into the area’s marshes.
“This clay dam was built inland to avoid direct wave contact, which would destroy it over time,” said Cooper. “Without this piece within the array of projects that are helping to restore and enhance the Chenier Plain, we wouldn’t have anything left to save.”
Cooper said that this clay berm is the beginning of a much bigger Beach Ridge and Dune Restoration project that he hopes will begin this coming fall.
“This larger piece of the project along the beach should provide a better long-term solution for preventing pulses of seawater from entering our marshes, plus it should also restore natural beach functions along the coastline,” he said.
Another key project that is helping to restore the Texas Chenier Plain has been the development of three freshwater siphons along the Intracoastal Waterway (ICW). Cooper said that these siphons were made to allow freshwater to flow from the north side of the ICW to the south side of the ICW within the Salt Bayou watershed system and surrounding marshes, ultimately bringing freshwater inflows in the area back to their historical levels.
“These siphons are allowing freshwater to flow south of the ICW for the first time since the 1930s when the waterway was developed,” said Cooper.
TPWD biologist and project manager for the JD Murphree WMA Mike Rezsutek said that efforts made to reduce the size of the Keith Lake Fish Pass have reestablished a healthy estuarine gradient within the Keith Lake and Johnson Lake Marsh Complex.
“From 1977-2010, the pass had tripled in size due to tidal action,” said Rezsutek. “This exponentially increased the amount of energy and water flowing into the system, which sped up erosion processes and destroyed marsh habitat. Huge swings in salinity also occurred in areas that should have remained around 10 ppt or less the majority of the time.”
Rezsutek said that the goal of the size reduction project for the Keith Lake Fish Pass was to prevent salinities in the area where Keith Lake and Johnson Lake meet from exceeding 10 ppt more than about 20 percent of the time. He said the project has been working great, thus far.
Rezsutek also said marsh restoration projects are underway within the Salt Bayou watershed and the Texas Chenier Plain to improve 1,000 acres of marsh lands.
“We are restoring the elevation of the marsh to historical heights so that these areas still receive tidal inflows but won’t become inundated and waterlogged,” he said. “This will allow traditional marsh vegetation to grow and flourish, and we are also planting vegetation to supplement what has been lost over time.”
Jefferson County Judge Jeff Branick said that he is already seeing positive effects from these projects. Branick grew up in the area and spent his childhood hunting and fishing along its marshes.
“All of these projects compound upon each other, and the resulting benefits are innumerable,” Branick said. “I am already seeing the angling opportunities within the region resemble those that I cherished during my youth.”
Branick said that the Texas Chenier Plain is quickly on its way to becoming the nursery grounds for fish, crustaceans and other aquatic and estuarine species that it has been historically known for.
Making the Connection
Freshwater inflows impact all aspects of upper Texas coast estuaries and marshes. From the fish that anglers love to pursue, to the habitat requirements such as oyster reefs and low salinity areas that these species rely on in order to thrive, the downstream flow of freshwater will always be a determining factor in the health and productivity of these ecosystems. The sooner that more and more Texans make this connection, the better the future of our upper coast estuaries will be.
Whoopers on the Texas Chenier Plain
Article by Nate Skinner
Photo by Larry Ditto
According to Wade Harrell, the Whooping Crane Recovery Coordinator for US Fish and Wildlife, a historical population of Whooping Cranes that inhabited the Chenier Plain, stretching from southeast Texas to southern Louisiana, were wiped out by hurricanes in the 1930s and 1940s. Harrell said that over the past 10 years, the Louisiana Department of Wildlife and Fisheries has been annually releasing whoopers from a captivity-reared stock in southwest Louisiana hoping to restore the species’ historical population throughout the Chenier Plain region.
“This population of Whooping Cranes is currently at about 75 birds,” Harrell said. “We are beginning to regularly see some of these birds visit and hang out along portions of the Texas Chenier Plain in southeast Texas.”
Harrell said that these whoopers are unlike the ones within the migrating wintering population found around the Aransas National Wildlife Refuge, which currently sits at about 500 birds.
“The Whooping Cranes we are seeing along the Texas Chenier Plain are a resident population,” Harrell said. “Their increased frequency in this ecoregion seems to correlate with the marsh restoration efforts that have been taking place there, along with the area’s relatively close proximity to the birds’ release sites.”
Harrell said that since the Texas Chenier Plain restoration and enhancement projects have been underway, more and more whoopers have been sighted along the area’s marshes and surrounding rice fields.
“Marsh restoration efforts in the Texas Chenier Plain region have definitely molded it into the right habitat for Whooping Cranes,” he said. “It is a similar habitat to where they were released in southwest Louisiana, and there is plenty of diverse food sources available for them there.”