1a.Objectives (from AD-416):
To assess the impact of Eurasian Watermilfoil introductions into streams in the Western US. Emphasis is to be placed on assessing the changes in insect fauna assocated with the displacement of native vegetation and its implications for the native foodweb. Additional specific consideration is to be given to assessing the introduction and impact of insect biolgoical control agents of Eurasian Watermilfoil in California and Alaska.
1b.Approach (from AD-416):
A combination of field sampling, laboratory assessment and experimental studies will be used to measure and assess the changes found in Western US stream where Eurasian Watermilfoil has invaded. Qualitative and quantitative models will be developed to compare actual sites of invasion with areas through to be high at risk for potential invasion. Cold water springfed streams will be the primary focus of study as they best represent Alaskan waters where Eurasian Watermilfoil is rated to be the State's largest exotic weed threat.
This research specifically addresses Objective 2 of the parent project through the development of predictive models of biological control potential. A new project was established with the University of California Davis to help address the impact of Eurasian watermilfoil in cold water streams in Northern California. Studies are currently being implemented on the Fall River which is California's largest spring-fed river. This river has very cold water temperatures all season which allows invasive milfoil to grow vigorously throughout the waterway. Detailed habitat characterization has been conducted in the river across 71 sample locations where both native and introduced vegetation is being assessed and studied in relationship to foodweb dynamics within the river. These plants provide both a source of primary production in the river and also serve as a substrate for epiphyte development. Epiphytes and/or microscopic organisms that grow on these plants also serve as the base of the food chain supporting aquatic insect that are the primary food source for the trout in this river. The river is further surrounded by agriculture operations that both use water from the river and release effluent into the river. ARS scientists from Albany, and Davis, California, are working with Univeristy of California Davis personnel to better characterize these associations and use them in more effective river management. The ARS Principal Investigator works closely with University of California Davis scientists to design and implement these studies and monitors this work closely. This project also supports a Pathways Student Trainee who is obtaining a PhD from University California Davis while working on this effort.