D3032: Analyzing macroinvertebrate communities in different habitat regimes of submerged aquatic vegetation post Hydrilla invasion in Lake Austin and Lady Bird Lake

Lady Bird Lake and Lake Austin are adjacent reservoirs in Austin, Texas with the primary functions of electrical power generation, flood control, and recreation. In 1999, the invasive submerged aquatic macrophyte (SAV), 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 SAV, giving rise to other nuisance species such as zebra mussels and harmful algae. SAV, in addition to facilitating nutrient uptake and retention, enhancing water clarity, stabilizing substrate, and attenuating wave energy, provides food and 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 macroinvertebrate community within different habitat regimes. The results indicate that the presence of SAV was important for the colonization of macroinvertebrate taxa diversity, abundance, and richness. This study shows the importance of SAV and will contribute to further management decisions in the City of Austin.