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Topics on Texas Aquatic Ecosystems

“Topics on Texas Aquatic Ecosystems”

A (Virtual) Lunchtime Lecture by Katie Vasquez and Megann Harlow

**UPDATE: This seminar was originally scheduled for 19-Feb-2021. 03-Aug-2021 is the new event date. 

Please join Katie Vasquez and Megann Harlow from University of North Texas as they present their research in our Student Research Seminar series. This 1-hr seminar will be divided into two 20-min presentations, each followed by a short Q&A.

“Analyzing the macroinvertebrate community dynamics within different habitat regimes of submerged aquatic vegetation (SAV): Post Hydrilla invasion in Lake Austin and Lady Bird Lake in Austin, Texas” — Katie Vasquez

Abstract: Lady Bird Lake and Lake Austin are adjacent river-like reservoirs in Austin, Texas, with the primary functions of electrical power generation, flood control, and recreation. In 1999, the invasive submerged aquatic macrophyte Hydrilla verticillata was observed in Lake Austin where it established over the span of the lake, though never establishing in Lady Bird Lake. Management strategies to eradicate Hydrilla, involving the stocking of sterile Asian grass carp, Ctenopharyngodon idella, nearly eliminated hydrilla from Lake Austin, but also resulting in overgrazing of native submerged aquatic vegetation (SAV) in both lakes, giving rise to other nuisance species such as zebra mussels and harmful algae. Since 2004 the City of Austin has been continually working to restore the SAV in these reservoirs. SAV, in addition to facilitating nutrient uptake and retention, enhancing water clarity, stabilizing substrate, and attenuating wave energy, provides food resources and habitat refugia for aquatic fauna. My research aims to understand the biological implications from the presence and absence of SAV in the two reservoirs by seasonally analyzing the benthic macroinvertebrate community within different habitat regimes. The results indicate that the presence of SAV was important for the colonization of benthic macroinvertebrate diversity and supported higher macroinvertebrate taxa abundance and richness. The study shows the importance of restoration of SAV and these results will contribute to further management decisions in the City of Austin.

Clockwise from top left: invasive Zebra mussels on a stick; head of mounted Chironomid larvae; Katie Vasquez on Lake Austin with the 360 Bridge in background


“Biomonitoring at Dallas/Fort Worth International Airport: Relating urban land use with aquatic life use” — Megann Harlow

Abstract: To determine the effectiveness of watershed protection practices, the Dallas/Fort Worth International (DFW) Airport sponsored a series of biomonitoring studies of the surrounding waterways. This study was conducted by the University of North Texas (UNT) Benthic Ecology Lab during the summers of 2004, 2005, 2008, and 2014. The objective of these studies was to identify the major human activities, within the urban watershed surrounding the airport, that could potentially affect water quality. These biomonitoring events included measurements of physicochemical parameters, habitat quality, and benthic macroinvertebrates populations. Additionally, land use analysis was conducted using 5-meter resolution satellite imagery of the watershed using eCognition, an object-based-image-analysis software. This information was used to identify geospatial variables, e.g. impervious surface cover, with the potential to impact water quality. One unique aspect of the approximately 17,000 acres of airport property, that was revealed in the spatial analysis, is a large tract of “protected” riparian forest that is rare in the urban surroundings. Benthic macroinvertebrate communities, along with other measured parameters, within the study area point to an improved stream condition downstream of this riparian forest. The results provide support for the benefits of an intact riparian forest within urban areas to improve stream conditions for aquatic life.

From top: airport upstream sampling site; Megann Harlow sitting at a microscope; assortment of aquatic invertebrate samples


Katie Vasquez and Megann Harlow are both graduate students in the Environmental Science program of the Department of Biology at University of North Texas in Denton, Texas. Their advisor is Dr. James Kennedy, Regents Professor and Director of the Elm Fork Education Center and Natural Heritage Museum.

This event is now over. A recording of the lecture is available here. Check out other past lectures here.

About the Research Lecture Series

The BRIT Research Lecture Series is designed to create community wide conversation about a diverse range of important and rapidly developing topics. This series gives scientists and speakers a forum for sharing the most current information about their areas of expertise and allows the public to interact with leading members of the local, national, and international scientific community. Read more at


Aug 03 2021


12:00 pm - 1:00 pm

The event is finished.


Brooke Byerley Best


Brooke Byerley Best