Tim Stewart's Home Page
Assistant Professor
Department of Natural Resource Ecology and Management
Iowa State University
Ames, IA 50010
(515) 294-1644
Research
My primary research focus involves use of aquatic organism population and community attributes (e.g., densities, biomass, diversity, taxonomic composition) to assess ecosystem health. Most current projects are intended to evaluate impacts of intensive agriculture and urbanization on water and habitat quality in wetlands, streams and rivers, and lakes. By quantifying spatial and temporal variation in biological components of ecosystems, we provide evidence of adverse environmental impacts that guide pollution abatement efforts, water and habitat quality management, ecosystem restoration strategies, and conservation of rare or ecologically/economically important species.
Current students and projects
Valerie Hentges (M.Sc.) - Relationships between macroinvertebrate community structure and environmental features in prairie pothole wetlands of northcentral Iowa (funded by Iowa Department of Natural Resources).
Mike Colvin (Ph.D.; co-advised with Dr. Clay Pierce) - Effects of two invasive species (common carp and zebra mussels) on water quality in Clear Lake, Iowa: an empirical and predictive modeling approach (funded by Iowa Department of Natural Resources).
Cassie Herringshaw (M.Sc.; co-advised with Dr. Janette Thompson) - A quantitative evaluation of managed riparian buffer impacts on in-stream environmental features and macroinvertebrate communities in urban and agricultural landscapes (funded by U.S. Environmental Protection Agency and Iowa Water Center).
Recent
Peer-reviewed Publications and Submissions
(*denotes
student author)
Stewart, T.W., and Downing, J. In press. Macroinvertebrate communities in recently constructed wetlands of an agricultural and urbanized watershed. Wetlands.
*Litvan, M.E., Stewart, T.W., Pierce, C.L., and Larson, C.J. 2007. Effects of grade control structures on the macroinvertebrate assemblage of an agriculturally-impacted stream. River Research and Applications (http://www3.interscience.wiley.com/cgi-bin/fulltext/117869169/PDFSTART?CRETRY=1&SRETRY=0)
*Litvan, M.E., C.L. Pierce, T.W. Stewart, and C.J. Larson. In review. Fish passage in a western Iowa stream modified by grade control structures. North American Journal of Fisheries Management.
*Litvan, M.E., C.L. Pierce, T.W. Stewart, and C.J. Larson. In review. Fish assemblage structure in a western Iowa stream modified by grade control structures. North American Journal of Fisheries Management.
Stewart, T.W., and Lowe, R.L. In review. The benthic algae of Lake Erie (1898-2004): taxonomic composition, ecology, and causes and consequences of community change. Journal of Great Lakes Research.
Stewart,
T.W. 2007.
Measuring animal movements in a natural ecosystem: a mark-recapture
investigation using stream-dwelling snails.
American Biology Teacher 69 (1) http://www.nabt.org/sites/S1/File/pdf/069-01-0028.pdf
Stewart,
T.W. 2006.
Observing
and quantifying predator-avoidance behavior: habitat shifts in snails threatened
by shell-crushing predators. Teaching
Issues and Experiments in Ecology, Volume 4.
Ecological Society of America.
Stewart, T.W. 2006. The freshwater gastropods of Iowa (1821-1998): taxonomic composition, geographic distributions, and conservation concerns. American Malacological Bulletin. 21:59-75.
Stewart, T.W. and Dillon, R.T. Jr. 2004. Species composition and geographic distribution of Virginia's freshwater gastropod fauna: a review using historical records. American Malacological Bulletin 19:79-91.
Stewart,
T.W., *Shumaker, T.L., and
*Radzio, T.A.
2003. Linear
and nonlinear effects of habitat structure on composition and abundance in the
macroinvertebrate community of a large river.
American Midland Naturalist 149:293-305.
Stewart,
T.W., and *Embrey,
T.R.
2003. Demonstrating
that habitat structure facilitates coexistence of predator and prey: a
laboratory experiment using goldfish and invertebrates.
American Biology Teacher 65:292-297.
Stewart,
T.W., and Garcia, J.E.
2002. Environmental
factors causing local variation in density and biomass of the snail Leptoxis carinata in Fishpond Creek, Virginia.
American Midland Naturalist 148:172-180.
Recent Presentations (*denotes
student)
Stewart, T.W. 2007. Freshwater gastropods of the Midwest: ecological functions, taxonomy, and conservation concerns. Midwest Fish and Wildlife Conference. Madison, Wisconsin.
*Colvin, M., Pierce, C.L., and Stewart, T.W. 2007. A simulation model to identify effective carp removal strategies for Clear Lake Iowa. Midwest Fish and Wildlife Conference. Madison, Wisconsin.
Stewart, T.W. 2007. Relationships between macroinvertebrate abundance and environmental features in recently constructed wetlands. North American Benthological Society. Columbia, South Carolina.
Stewart, T.W. 2007. Macroinvertebrate communities, carp invasions, and constructed wetlands. Iowa/Nebraska/Kansas Meeting of the American Fisheries Society. Council Bluffs, Iowa.
*Litvan, M.E., Pierce, C.L., Stewart, T.W., and Larson, C.J. 2006. Evaluation of fish passage and and fish and macroinvertebrate communities in southwest Iowa streams modified by grade control structures. Iowa/Wisconsin Meeting of the American Fisheries Society. Dubuque, Iowa, and American Fisheries Society, Anchorage, Alaska.
Stewart, T.W. 2005. Using aquatic macroinvertebrates to evaluate ecosystem health in Iowa's agricultural and urbanized landscapes. Department of Natural Resource Ecology and Management, Iowa State University.
Stewart, T.W. 2005. The freshwater gastropods of Iowa (1821-1998): species composition, geographic distributions, and conservation concerns. Freshwater Mollusk Conservation Society. St. Paul, Minnesota.
*Litvan, M.E., T.W. Stewart, and C.L. Pierce. 2005. Evaluation of macroinvertebrate assemblage structure in a southwest Iowa stream with grade control structures. Annual Meeting of the Iowa Academy of Sciences. Cornell College.
*Rosauer, D.R., and T.W. Stewart. 2005. Causes of spatial variation in macroinvertebrate abundance and diversity in a newly constructed wetland receiving urban runoff. Annual Meeting of the Iowa Academy of Sciences. Cornell College.
Recent Reports, etc.
The Freshwater Gastropods of Georgia
The Freshwater Gastropods of North Carolina
The Freshwater Gastropods of South Carolina
The Freshwater Gastropods of Virginia
Teaching
AECL 312 (General Ecology)
AECL 366 (Natural History of Iowa Vertebrates)
AECL 366 (Natural History of Iowa Vertebrates) Homepage
AECL 515 (Ecology and Identification of Freshwater Invertebrates)