Habitat Field Crew : The Meadows Center for Water and the Environment : Texas State University

As of 2020, the Habitat Field Crew is following a top-down removal strategy of aquatic invasive species in the San Marcos River. Hydrilla is currently being maintained from Spring Lake to the State Scientific Area just downstream from Hopkins St, and is visually undetectable throughout this zone. Removal efforts regarding hygrophila are currently taking place throughout Spring Lake with the goal of catching up with the hydrilla progress by 2021.

Habitat Conservation Plan

Texas State University is home to the San Marcos River and Spring Lake: a spring-fed system arising from the depths of the Edwards Aquifer that hosts numerous threatened and endangered species ranging from blind salamanders to wild rice. Under the Edwards Aquifer Authority, the City of San Marcos began the implementation of the Habitat Conservation Plan in 2013 with a focus on restoring the immediate environment in and around the San Marcos River. These tasks range from bank stabilization and impervious cover management, to conservation outreach and control of non-native species; however, the Meadows Center’s Habitat Field Crew focuses on aquatic habitat restoration.

Habitat Field Crew

The Meadows Center for Water and the Environment is tasked with the restoration of aquatic habitat within the Upper San Marcos River. Specifically, the Habitat Field Crew is responsible for the control of non-native aquatic vegetation, enhancement of Texas Wild-rice and the mitigation of floating vegetation mats that accumulate on native submerged aquatic vegetation in the river.

Our crew is composed of staff, student workers, students with work study awards, and volunteers, who all play an active role in the City of San Marcos Conservation Plan; whether it’s through SCUBA diving and snorkeling on a regular basis, inputting data into GIS software, or presenting our work at various conferences.

Native Submerged Aquatic Vegetation Restoration

Continued efforts to restore native submerged aquatic vegetation populations in the Upper San Marcos River have been successful, from Texas Wild-rice enhancement in Spring Lake to Hydrilla mitigation down to the I-35 transect. However, the efficiency of native submerged aquatic vegetation restoration has increased with the implementation of a thorough, top-down removal strategy for non-native species, in conjunction with the natural expansion of surrounding natives.

Hydrilla is the primary invasive species in the San Marcos River and can persist for years following the initial removal due to the reproductive capabilities of its root structure. This requires divers on the crew to routinely do extremely thorough searches of the river in order to prevent hydrilla from reestablishing.

Hygrophila is another aquatic, invasive species that has the capacity to grow in riparian conditions along the bank, and while not as aggressive as hydrilla, still poses a significant threat to the success of native submerged aquatic vegetation populations in the San Marcos River.

Research Projects

The Habitat Field Crew assists faculty and staff from Texas State University, as well as other institutions, on various projects that require aquatic field work. Our involvement with the Edwards Aquifer Habitat Conservation Plan has provided our crew with specialized SCUBA skills that many of these projects require: any members who participate on these endeavors donate their time to do so, but the experience is always worthwhile.

The most recent projects have included SCUBA dives to conduct mark-recapture population surveys on the Big Claw River Prawn and the PIT tagging of Suckermouth Armored Catfish to assess dispersal capacity and quantify habitat associations. In the past we have worked alongside San Marcos Aquatic Resources Center on annual Texas Wild-rice surveys, performed visual surveys to estimate Fountain Darter populations, and identified macroinvertebrates collected from drift nets to assess the health of the aquatic community in the San Marcos River.

Field Technology

While the Habitat Field Crew primarily resides in and around the aquatic environment, we’ve had opportunities to collaborate with other departments on projects involving the use of unmanned aerial vehicles (UAV) to gather aerial imagery across many parts of Texas. These projects have utilized this type of technology to survey bird populations along the Texas Coastline, as well as classify suitable vegetation types in parts of the Permian Basin for a desert lizard species. We were also contracted to conduct a pilot study requiring the deployment of vegetation booms within in Spring Lake in an attempt to mitigate vegetation discharge from the lake and the resulting damage to native submerged aquatic vegetation in the river.