Associate Professor
Department of Biological Sciences
Towson University
Towson, MD 21252 USA
Office: Smith 223
Phone: 410-704-4368
Fax: 410-704-2405
email: sgresens@towson.edu
Education:
Ph.D. University of Chicago
M.S. University of Wisconsin
B.S. S.U.N.Y. College at Oneonta
Courses Taught:
BIOL 208 - Biological Diversity
BIOL 402 - General Ecology
BIOL 406 - Limnology
BIOL 609 - Community Analysis & Bioassessment
Research Interests:
My area of specialization is freshwater ecology, with a focus on stream ecosystems. Most of my research involves midges (Diptera: Chironomidae), a family of aquatic insects with high species diversity and an amazing range of ecological specialization. In addition, I have a long-standing interest in algal-grazer interactions.
I am currently using collections of chironomid pupal exuviae (cast pupal exoskeletons) to study the response of species diversity to urbanization in 24 streams in the Baltimore area. Using a similar approach, I am also collaborating with Dr. Leonard C. Ferrington, Jr. and the Chironomidae Research Group (http://www.entomology.umn.edu/midge) at the University of Minnesota, on a survey of chironomid species diversity along Minnehaha Creek, an urban stream in the Minneapolis metropolitan area.
Periphyton (i.e., attached algae) are an important component of the base of stream food webs; periphyton provide both food and habitat for many chironmids and other aquatic invertebrates. Other areas of my research include experimental studies of the effects of silt/clay sediments on nutrient limitation of periphyton, and an analysis of the dynamics of periphyton biomass in urban streams in relation to nutrients and hydrologic variability.
Publications:
Gresens, S.E., K.T. Belt, J.A. Tang, D.C. Gwinn and P.A. Banks. 2007. Temporal and spatial
responses of Chironomidae (Diptera) and other benthic invertebrates to urban stormwater
runoff.Hydrobiologia 575:173-190.
Gresens, S.E. and L.C. Ferrington, Jr. 2007. Chironomid species richness in streams draining
areas of serpentine vs. non-serpentine bedrock. Proceedings of the XVth International
Symposium on Chironomidae. (accepted).
Lawrence, J.M. and S.E. Gresens. 2004. Response of periphyton and grazers to nutrient
enrichment in rural vs. urban streams. Journal of Freshwater Ecology 19:375-385.
Gresens, S.E. 2001. Thermal sensitivity of ingestion and digestion in larvae of a
eurythermal chironomid. Journal of the North American Benthological Society 20: 68-83.
Gresens, S.E.1997. Interactive effects of diet and thermal regime on growth of the midge
Pseudochironomus richardsoni. Freshwater Biology 38:365-373.
Gresens, S.E. 1995. Grazer diversity, competition and the response of the periphyton
community. Oikos 73:336-346.
Current Graduate Students:
Megan Green: “Phosphorus sorption properties of silt-clay sediments, and their impact on
nutrient status and growth of periphyton”
Cory Lavoie: “Use of chironomid pupal exuviae in bioassessment of Baltimore County streams”
Undergraduate Students:
Jacqueline Carroll: “Effects of suspended clays on phosphorus-limitation of periphyton”
Michael Edillon: “Impact of kaolin clay and N:P ratio on P-limitation of periphyton”
Angela Pacelli: “Emergence phenology of Chironomidae in Deep Run”
Teresa Bartley: “Effects of suspended clays on the base of stream foodwebs”