Author
Megan K Reid
megan.reid@ufl.edu
University of Florida
USA
Coauthors
Linhao Xu, University of Miami, Coral Gables, FL, USA
Donald L DeAngelis, University of Miami, Coral Gables, FL, USA
Lyn A Gettys, University of Florida, Davie, FL, USA
Melissa C Smith, USDA-ARS IPRL, Davie, FL, USA
Abstract
Evidence from existing literature demonstrates the importance of bottom-up forces in driving plant invasions. Similarly, biological control operates on the notion that top-down effects, through herbivory by natural enemies, impact the ability of an invasive plant to outcompete other species. In the context of aquatic plants, there is evidence that differences in nutrient loads can result in alternative stable states in which floating aquatic vegetation (FAV) dominates in eutrophic settings, and submerged aquatic vegetation (SAV) dominates in oligotrophic settings. Few studies, however, have investigated the interactive effects of herbivory with nutrient load on these stable states. Mathematical and simulation modelling of the competitive interactions of SAV with FAV can predict how various factors can affect competition outcomes, but experimentation is necessary to test the predictions. Hence, we aimed to experimentally test modelling conclusions using mesocosm experiments pairing invasive and native aquatic macrophytes in Florida, USA. We grew the floating invasive Pontederia crassipes with two native submerged and native rooted, floating-leaved species under conditions of high and low nutrients with and without herbivory. We replicated this same setup using Limnobium spongia, a native floating plant, in the place of P. crassipes, and modelled changes in biomass across treatments. The results of this study elucidate useful information to aid management of invasive FAV and restoration efforts in freshwater ecosystems.
Keywords:
Stable states
Waterhyacinth
Biological control
Aquatic invasive species
Nutrients
highlights:
Nutrients affect growth of FAV more than herbivory.
Herbivory reduces FAV growth even at high nutrient loads.
Past models of stable state shifts can be applied to other interactions of FAV and SAV.