B.S. University of Michigan
M.A. Western Michigan University
Ph.D. University of Michigan

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C-RUI Research:

Microbial processes and patterns at the interface between groundwater and surface water within reservoir littoral zones may help explain the dynamics of littoral-zone community ecology. We know that the contributions of microbial communities to chemical transformations occurring in sediments and water are important in the biogeochemical cycling of nutrients. I am interested in benthic microbial processes in the sediments of aquatic ecosystems (streams, lakes, and reservoirs). Bacterial metabolism influences the flux of nutrients between the sediments and overlying waters by regulating oxygen respiration, DIC and DOC release, and nitrate, ammonium, and phosphorus exchange.

Surface-subsurface hydrological exchange is presently being studied by a separate grant funded by the U.S. Department of Energy. Kentucky Lake experiences fluctuations in water level regulated at Kentucky Dam 20 miles away. One of our project hypotheses is that water level fluctuations alter physicochemical conditions at the littoral zone of reservoirs. By altering the degree of hydration of these littoral sediments, microbial community activities are altered as well.

Students I mentor collect sediments from Ledbetter embayment in Kentucky lake; these collections occur concurrently with independent flux experiments in benthic chambers. Bacterial abundance, enzyme activity, and productivity are monitored and correlated with water seepage rates into or out of the littoral zone during summer and winter pool water levels over a longer time scale.

I am interested in expanding on the concepts that reservoir littoral zones are 1) storage zones for solutes (dissolved inorganic nutrients and dissolved organic carbon), 2) hydrological gradients across which microbially-mediated nutrient transformations occur, and 3) the release or retension of nutrients from these hydrological storage zones to the reservoir is affected by water level management practices.

Publications

Hendricks, S.P., and D.S. White. 2000. Stream and ground-water influences on phosphorus biogeochemistry, pages 221-235. In: Jones, J.J. and P.J. Mulholland (eds.), Streams and Ground Waters. Academic Press.

White, D.S., and S.P. Hendricks. 2000. Lotic macrophytes and surface-subsurface exchange processes, pages 363-379. In: Jones, J.J. and P.J. Mulholland (eds.), Streams and Ground Waters. Academic Press.

Hendricks, S.P and G. Rice. 2000. Utilization of a specially-designed sediment colonization chamber for examining hyporheic microbial communities. Journal of Freshwater Ecology, in press.

Hart, D.R., P.J. Mulholland, E.R. Marzolf, D.L. DeAngelis, and S.P. Hendricks. 1999. Relationships between hydraulic parameters in a small stream under varying flow and seasonal conditions. Hydrological Processes 13: 1497-1510.

P.A. Bukaveckas, J.D.Williams, and S.P. Hendricks. 1999. Effects of nutrients and water residence time on phytoplankton and bacteria in a large river impoundment (Kentucky Lake). In review, Hydrobiologia.

Duff, J.H., G.H. Aiken, A.P. Jackman, F.J. Triska, and S.P. Hendricks. 1999. Sources and quality of dissolved organic carbon in the Shingobee River, Minnesota: implications for microbial utilization. Bulletin of the annual meeting of the Geomicrobiological Society, Crested Butte, CO, Aug. 1999.

Mulholland, P.J., E.R. Marzolf, J.R. Webster, D.R. Hart, and S.P. Hendricks. 1997. Evidence that hyporheic zones increase heterotrophic metabolism and phosphorus uptake in forested streams. Limnology and Oceanography, 42: 443-451.

Hendricks, S.P. 1996. Bacterial biomass, activity, and production within the hyporheic zone of a north-temperate stream. Archiv für Hydrobiologie 136: 467-487.

Hendricks, S.P. and D.S. White. 1995. Seasonal biogeochemical patterns in surface water, subsurface hyporheic, and riparian groundwater in a temperate stream ecosystem. Archiv für Hydrobiologie 134: 459-490.

Mulholland, P.J., E.R. Marzolf, S.P. Hendricks, R.V. Wilkerson and A.K. Baybayan. 1995. Longitudinal patterns in periphyton biomass, productivity, and nutrient cycling: a test of upstream-downstream linkage. J. No. Amer. Benthol. Soc. 14: 357-370.

Hendricks, S.P. 1993. Microbial ecology of the hyporheic zone: a perspective on the integration of hydrology and biology. J. No. Amer. Benthol. Soc. 12: 70-78.

Hendricks, S.P. 1992. Bacterial dynamics near the groundwater-surface water interface (hyporheic zone) of a sandy-bed, third-order stream in northern Michigan, p. 27-35. In: Stanford, J.A. and J.J. Simons (Eds.). Proceedings of the First International Conference on Ground Water Ecology. American Water Resources Association, Bethesda, Maryland.

White, D.S., S.P. Hendricks, and S.L. Fortner. 1992. Groundwater-surface water interactions and the distributions of aquatic macrophytes, p. 247-255. In: Stanford, J.A. and J.J. Simons (Eds.). Proceedings of the First International Conference on Ground Water Ecology, American Water Resources Association, Bethesda, Maryland.

Hendricks, S.P. and D.S. White. 1991. Physicochemical patterns within a hyporheic zone of a northern Michigan river, with comments on surface water patterns. Can. J. Fish. Aq. Sci. 48: 1645-1654.

Hendricks, S.P. and D.S. White. 1988. Hummocking by lotic Chara (Charales): observations on alterations of hyporheic temperature patterns. Aquatic Botany 31: 13-22.

White, D.S., C.H. Elzinga, and S.P. Hendricks. 1987. Temperature patterns within the hyporheic zone of a northern Michigan river. J. No. Amer. Benthol. Soc. 6: 85-91.