Research Interests: Aquatic food-web dynamics, plankton ecology

Research Description:  My research interests are in the fields of limnology and aquatic ecology. What past projects and current work have in common is my general interest in the dynamics and regulation of food webs, those networks of feeding relationships in ecosystems such as lakes, streams, and wetlands. In particular, I have questions about how habitat characteristics affect the interactions of aquatic species, or, from a different perspective, how the characteristics of some species may affect the aquatic ecosystem in which they live. I have worked on projects in diverse variety of project field sites, including freshwater and marine, temperate and arctic aquatic ecosystems.

Current projects are based on a field study of Sites Lake, OH.  I and my students began investigating the (1) dynamics of the zooplankton in this small kettle lake in 2003.   Most of that work has worked on documenting daily movement of microscopic animals in and out of the lake’s central open water area (daily horizontal migration).  Our evidence for this behavior is consistent with predator-avoidance, i.e. zooplankton aren’t as easily seen by fish in the dark, so seeking a daytime refuge helps them to survive.

A related question is the focus of my lab’s current summer research program.  Aquatic ecologists are just beginning to understand the (2) importance of species-specific chemical cues to informing other organisms about current threats and opportunities in their local environment.  So far on this project, my lab has been developing methods for testing response of Daphnia to different chemical stimuli derived from lake organisms in tank experiments. These assays should allow us to evaluate important species interactions and, possibly, some tradeoffs where conflicting signals are present in the environment.  We expect to be working with Dr. Jeff Wiedenhamer (AU Dept. of Chemistry) on initial characterization of chemical signals once tank experiments show clear effects of isolated treatments.  This project will contribute to the early body of work on “infochemicals” and their importance to lake community interactions.  There is also some limited evidence in the science-research literature that environment pollutants can interfere with infochemical function, so this basic research is potentially important to science’s understanding of pollution impacts on aquatic ecosystems.

Lastly, I am on study-leave in Fall 2010.  I will spend most of that time writing two manuscripts with Dr. Don Deibel (Memorial University, Canada).  These papers are based on two projects that began with field work in the North Water Polynya, a large and productive ocean region between Ellesmere Island, Canada, and NW Greenland.  One focuses on the ecology and biology of a gelatinous animal that can be very abundant and important to food webs: a group of species called appendicularians.  The second project focuses on measuring the diets and feeding rates of small crustaceans called copepods that live suspended in these same open ocean waters.  What these two projects have in common is that they (3) provide detail about how these animals make a living in an understudied region of the ocean, including brand new information about how they make a living in the later half of their “growing season.”  This region of the world is experiencing rapid climate change and loss of ice, which is a key factor in structuring the habitat and food supply of these animals.  The very large-scale and interdisciplinary project in which these two studies are embedded serves as a baseline for all future work in this changing region.

Students in this lab: 

I have mentored 12 research students in my years at AU.  Almost all of these students have be co-authors on presentations at professional society meetings where ecologists and aquatic biologists like to present their recent work and talk to each other:

The Ecological Society of America (ESA)

The North American Benthological Society (NABS)

The American Society of Limnology and Oceanography (ASLO)

For three summers (2009-2011), I am co-sponsoring a full-time summer research student along with Dr. Jeff Weidenhamer (AU Dept. of Chemistry).  This project is one of four AU projects supported by an undergraduate research grant from the Merck Foundation/American Association for the Advancement of Science.  In 2009 and 2010, that student is Rachel E. Day (AU’10).  In August 2010, Rachel attended the annual ESA meeting in Pittsburgh, PA, where she presented a poster about some of her work.  She has been developing a method that enhances a researcher's ability to study the activity of a microscopic invertebrate, Daphnia, that is common in lake and pond food webs.