Invasive Bivalve Establishment as a Secondary Effect of Eradication-Focused Nuisance Aquatic Plant Management
David Holbrook*1,2, Aaron Schad2, Gary Dick2, LyndeDodd2, James Kennedy3
1Consultant for the Department of Energy Office of Legacy Management, Grand Junction, CO, USA, David.Holbrook@lm.doe.gov
2US Army Engineer Research and Development Center, Environmental Lab, Lewisville Aquatic Ecosystem Research Facility, Lewisville, TX, USA, Aaron.N.Schad@usace.army.mil, Gary.O.Dick@usace.army.mil, Lynde.L.Dodd@usace.army.mil
3Advanced Environmental Research Institute, Department of Biological Sciences University of North Texas, Denton, TX, USA, James.Kennedy@unt.edu
We evaluated changes in aquatic vegetation cover and community structure in hydrilla (Hydrilla verticillata) infested earthen ponds after applying the management tools: triploid grass carp (Ctenopharyngodon idella) stockings, herbicide applications, and native emergent, floating-leaved, and submersed species plantings. In units where aquatic vegetation was most reduced due to management (herbicide and >72 grass carp per vegetated hectare stockings), a secondary infestation of the invasive bivalve (Asian clam or Corbicula fluminea) was observed. Asian clam abundances were analyzed in relation to grass carp stocking densities (0, 40-42, 72-81, 110-129 per vegetated hectare), depth, and changes in native and invasive vegetation community structure and cover. Data analyses showed inverse relationships of Asian clam abundances to vegetation cover, and depth, as well as a synergetic relationship with grass carp stocking density. Implications of this research indicate that when a nuisance aquatic plant management strategy is more focused on full or near eradication of a target species with inevitable native bystanders rather than a holistic strategy preserving beneficial ecological components, secondary issues are likely to occur, such as the establishment of additional invasive species.