**The title, authors, and abstract for this completion report are provided below.  For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**

EXOTIC INVERTEBRATES, FOOD-WEB DISRUPTION, AND LOST FISH PRODUCTION:

UNDERSTANDING IMPACTS OF DREISSENID AND CLADOCOCERA INVADERS ON LOWER-LAKES

FISH COMMUNITIES AND FORECASTING INVASION IMPACTS ON UPPER LAKES FISH COMMUNITIES

Brian J. Shuter¹ and Doran Mason²

¹ Department of Ecology and Evolutionary Biology,

University of Toronto,

25 Harbord Street,

Toronto, Ont M5S 3G5

email: shuter@zoo.utoronto.ca

² NOAA Great Lakes Environmental Laboratory

2205 Commonwealth Blvd

Ann Arbor, MI 48105

email: Doran.Mason@noaa.gov

ABSTRACT

Development and coordination of a Research Theme on the disruption of Great Lakes food webs by invertebrate invaders was carried out over the years from 2000 to 2006. A White Paper was prepared in 2001 that justified focusing research funding on this issue and laid out initial priorities for research. Four workshops and 1 Symposium were organized over this same period to promote information exchange among scientists working in the field and to re-evaluate and modify the research directions defined in the original White Paper. In addition, research was carried out on the role of spatial heterogeneity in shaping aquatic food web structure, and particularly on its role in shaping the sensitivity of existing food webs to invertebrate invasions. This research led to the production of four peer-reviewed publications and 1 Ph.D. thesis. A brief summary of each follows: (i) Noonburg, Shuter and Abrams 2003: the authors show that the effects of spatial structure on the intensity of within-basin turbulent mixing can produce large differences in the direct and indirect effects of zebra mussel filtering on both phytoplankton and zooplankton dynamics; (ii) Byers and Noonburg 2003: the authors show that the spatial scale of an invasion study can have a strong effect on its results: a negative relationship between invasion success and indigenous species diversity at a small spatial scale can, under reasonable assumptions, convert into a positive relationship at larger spatial scales; (iii) Noonburg and Abrams 2003: the authors show that an invasion by a predator-resistant prey species can lead to the extinction of native prey species; (iv) Noonburg and Byers 2005: the authors show that the extinction of native prey can be driven by the positive effect that an invading prey species can have on a native predator; (v) Richards PhD Thesis, expected completion – spring 2007: the author shows that the fine scale spatial patterning in phytoplankton and zooplankton communities, in both relatively small and relatively large water bodies, is an important factor determine the rate of trophic transfer from phytoplankton to zooplankton.