There are several problematic invasive species of aquatic plants and algae in the southeastern U.S. These organisms create management concerns that can lead to recreational use losses aquatic…

There are several problematic invasive species of aquatic plants and algae in the southeastern U.S. These organisms create management concerns that can lead to recreational use losses aquatic habitat degradation and fish kills. For example hydrilla golden algae giant salvinia and didymo all negatively impact water bodies used for swimming fishing and boating. Some of the invasive species also form hybrids with native plants in some cases outperforming the native species as in the case of native eelgrass valisneria americana. Native plants provide sediment stabilization aquatic habitat for macroinvertebrates assist in nutrient uptake and provide juvenile habitat for fishes. IT becomes difficult to effectively manage aquatic habitats as these invasives and hybrids cause uncertainties in both identification and control strategies. The threats from these species present a formidable challenge with significant ecological and economic impacts. This is especially relevant for the tennessee river which runs through tennessee alabama mississippi and kentucky. The tennessee department of environment and conservation tdec and the tennessee valley authority TVA are charged with treatment of aquatic systems to manage and control aquatic invasive plants. Within the tennessee river eelgrass and hydrilla are the main invasives causing damage to aquatic habitats. Currently native eelgrass is being rapidly displaced by the invasive species v. Spiralis with hybrids outperforming both species. In tennessee IT has been suggested that there are at least six unique hydrilla biotypes that require further study. These biotypes vary in their propensity to form dense mats tolerance of water temperature and the degree of asexual reproduction that occurs. Control methods have lagged behind the rapid spread and adaptation of the plants to the tennessee river system. In order to assist managers working in these systems extensive sampling using both traditional and molecular approaches is needed to identify which species or biotypes are present and how they are spreading. We propose a study that uses multiple approaches to address the issues described above. 1 we will conduct extensive field surveys on the tennessee river to evaluate plant community composition in suspected areas of aquatic invasive plant establishment in the tennessee river and tributaries. With these samples we will be able to provide useful identifying characteristics for hybrids biotypes and species. 2 we will complement these surveys with genetic approaches using environmental DNA metabarcoding to detect plant species or hybrids that might be missed using traditional sampling methods. The molecular data will also help US to identify and hopefully anticipate patterns of invasive spread. 3 both traditional and molecular sampling will be used to compare fish and invertebrate diversity in areas where native plants remain versus those where invasive species have established. This can help managers prioritize areas for control interventions based on how greatly the animals are being affected. 4 we also plan to conduct controlled experiments to measure how native and invasive species interact to affect plant growth and establishment. The data collected will enable managers to identify signs of early invasion or maintain sites in a manner that discourages invasive establishment. We anticipate this work will provide meaningful insights to both tdec and TVA facilitating a greater understanding of which species hybrids or biotypes are present how they are spreading how they become established and what direction they are moving. Agencies in the southeast are overwhelmed with aquatic invasive plant management and control needs as more invasives are introduced each year.