Invasion ecology


Three recent PhD projects in my lab (Jenn Rehage, now an assistant professor at Florida Intl U; Lauren Pintor, now an assistant professor at Ohio State U; and Val Brenneis, now an instructor at Portland State) examined species traits that underlie species interactions that help to explain invasion success and impacts of key invaders (mosquitofish, signal crayfish, and New Zealand mudsnails) on aquatic communities.  These studies highlight the importance of aggression, foraging and antipredator behavior and their influence on competition and predator-prey interactions.  The work on invasive crayfish was funded by a competitive National Sea Grant with Lee Kats (Pepperdine U).

Most recently, my lab garnered major grants from the Department of Water Resources and the Bureau of Reclamationto do repeated, large-scale field surveys at 33 sites spread over much of the Sacramento Delta, along with mesocosm experiments and behavioral studies to examine effects of an invasive waterweed (Egeria densa) on the recent, explosive increase in exotic, shallow-water, predatory largemouth bass, and impacts of these bass on the overall aquatic community including both exotic species and threatened or endangered native taxa.  This project represents a significant expansion of my research program from smaller-scale, experimental studies focusing on behavior and species interactions in small streams and ponds, to a much larger applied project on predator-prey interactions on a landscape scale.  The first paper associated with this project was a collaborative, sophisticated, multivariate time series analysis of food web interactions in the SF estuary-Sacramento delta (Mac Nally et al. 2010).  Several additional papers are now in preparation. This work is led by a former postdoc, Louise Conrad (now a chief scientist at the DWR), and involves 2 graduate students (Dave Harris, Kelly Weinersmith), and 3 technicians who have all moved on to be graduate students (Matt Young, Andrew Bibian, Denise DeCarion), along with collaborations with Peter Moyle, and several agency scientists.