The Role of Competitive Interactions, Phenolics, and Feeding by Mesograzers in Eurasian Watermilfoil (Myriophyllum Spicatum) Invasions
Jenna Larson: Biology major, 2019
Rachel DeMarzo: Biology major, 2019
Abstract
Invasive plants can spread to a degree that disrupts the structure of an ecosystem and causes damage to the environment. Factors contributing to plant invasiveness are incompletely understood, but elevated levels of chemical deterrents may enhance invasion success. This study examined competitive interactions, chemical defense production, and palatability in native Ceratophyllum demersum (coontail) and invasive Myriophyllum spicatum (milfoil). A laboratory competition experiment examined differences in C. demersum and M. spicatum growth in monoculture and polyculture. Since coontail can allelopathically reduce the growth of some plants, M. spicatum was grown in water containing chemical cues from each species. Field-collected samples of each species were freeze dried and ground for phenolic analysis and a palatability experiment. Freeze-dried, ground tissue from each plant species was incorporated into an artificial diet that was offered to amphipods (Gammarus sp.) in a choice feeding experiment. Coontail grew similarly well in both monoculture and polyculture, while milfoil grew better in polyculture. Milfoil growth was lowest in milfoil-conditioned water that contained its own chemical cues, showing that coontail did not allelopathically inhibit the growth of milfoil. Phenolic analysis and the choice feeding experiment are currently underway, but it is expected that milfoil will contain more phenolics than coontail, which should lead to greater amphipod feeding on the agar food made with coontail than with milfoil. Although other factors could affect competitive interactions and plant palatability, the results suggest that coontail can successfully compete with milfoil and that herbivores may alter competitive interactions between these species.
The Role of Competitive Interactions, Phenolics, and Feeding by Mesograzers in Eurasian Watermilfoil (Myriophyllum Spicatum) Invasions
University Commons
Invasive plants can spread to a degree that disrupts the structure of an ecosystem and causes damage to the environment. Factors contributing to plant invasiveness are incompletely understood, but elevated levels of chemical deterrents may enhance invasion success. This study examined competitive interactions, chemical defense production, and palatability in native Ceratophyllum demersum (coontail) and invasive Myriophyllum spicatum (milfoil). A laboratory competition experiment examined differences in C. demersum and M. spicatum growth in monoculture and polyculture. Since coontail can allelopathically reduce the growth of some plants, M. spicatum was grown in water containing chemical cues from each species. Field-collected samples of each species were freeze dried and ground for phenolic analysis and a palatability experiment. Freeze-dried, ground tissue from each plant species was incorporated into an artificial diet that was offered to amphipods (Gammarus sp.) in a choice feeding experiment. Coontail grew similarly well in both monoculture and polyculture, while milfoil grew better in polyculture. Milfoil growth was lowest in milfoil-conditioned water that contained its own chemical cues, showing that coontail did not allelopathically inhibit the growth of milfoil. Phenolic analysis and the choice feeding experiment are currently underway, but it is expected that milfoil will contain more phenolics than coontail, which should lead to greater amphipod feeding on the agar food made with coontail than with milfoil. Although other factors could affect competitive interactions and plant palatability, the results suggest that coontail can successfully compete with milfoil and that herbivores may alter competitive interactions between these species.
