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:
Dr. Gresens specializes in freshwater ecology, with a focus on stream ecosystems. Much of her research involves midges (Diptera: Chironomidae), a family of aquatic insects with high species diversity and an amazing range of ecological specialization. Several research projects in her lab involve the use of floating chironomid pupal exuviae (cast pupal exoskeletons) to study the response of species diversity to urbanization in streams in the Baltimore area. The ultimate goal of these projects is to develop statistical tools for bioassessement (tolerance values, biotic indices) that will be more sensitive to changes in ecological health of urban and suburban streams.
Another research focus involves periphyton (i.e., attached algae), an important component of the base of stream food webs, and a habitat for many aquatic invertebrates. Dr. Gresens maintains a long-standing interest in algal-grazer interactions, and studies mechanisms by which phosphorus limitation can influence the growth of both periphyton and invertebrate consumers in streams. This has involved surveys of periphyton dynamics in local streams in relation to temporal variation in nutrients and disturbance. In addition, her students conduct experimental studies of the effects of silt/clay sediments on nutrient limitation of periphyton in the laboratory.
Publications:
Gresens, S.E. and L.C. Ferrington, Jr. 2009. Chironomid species assemblages of streams draining areas of serpentine vs.
non-serpentine bedrock. Proceedings of the XVth International Symposium on Chironomidae. (In press).
Gresens, S.E. and L.C. Ferrington, Jr. 2008. Taxonomic distinctness provides an alternative view of the diversity of chironomid
(Diptera) assemblages. Boletim do Museu Municipal do Funchal Sup. No. 13: 101-108.
Sinclair, C.S. and S.E. Gresens. 2008. Discrimination of Cricotopus sp. (Diptera: Chironomidae) with mitochondrial gene
Cytochrome oxidase I sequence. Bulletin of Entomological Research 98:555-563.
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:
Cory Lavoie: “Use of chironomid pupal exuviae in bioassessment of Baltimore County streams”
Undergraduate Students:
Sasha Karosas TU REU student – University of Wisconsin- La Crosse: “Effects of silt-clay
sediment in a phosphorus-limited algal-grazer food chain”
Kristin Fischer “Effects of flood disturbance on chironomid emergence”
Christine Luehman “Biotic impacts of sediment-bound metals in streams”
John Siwinski “Comparing toxicity of streamwater using a Ceriodaphnia assay”