Is hybrid watermilfoil the next resistant invader?
MAISRC researcher Dr. Dan Larkin and his team recently kicked off a new project that aims to find out if hybrid watermilfoil is as big of a problem as some suspect. This project will answer this frequently asked question by quantifying differences in performance and competition between Eurasian, native, and hybrid milfoil.
Since the arrival of hybrid milfoil in Minnesota, there has been evidence – some anecdotal, some shown in the lab – regarding its increased invasiveness and resistance to herbicide. Since it is continuing to spread throughout northern states, and because Eurasian watermilfoil is already a challenging plant to manage, now is a critical time to learn more about this species. By assessing its invasiveness under different environmental conditions, this research will help prioritize hybrid watermilfoil management efforts, like how to make herbicide treatments most effective.
The first goal of the project is to evaluate competition between hybrid and parental watermilfoil species. To test whether hybrids really are growing bigger, faster, and stronger than their native or non-native parents, 30 tanks were set up with three sets of plants in each. The tanks are large enough to act as a mesocosm which mimics natural conditions more accurately than a laboratory can. Within the set, each species is rooted separately to ensure that they’re not competing for soil resources, but placed next to each other so that the native, Eurasian, and hybrid milfoils do all compete for other resources like sunlight and carbon dioxide.
Later phases of this project will include quantifying the differences in growth between species under different environmental conditions and investigating differences in phenology of each species. These experiments work to establish performance under different water depths and nutrient levels, which are key environmental factors that can influence invasiveness. They are also significant elements of what’s been missing in smaller lab studies or anecdotal accounts. To learn more about Eurasian watermilfoil research at MAISRC, please click here.