As an aquatic ecologist, my research broadly focuses on the role biological processes play in the transformations, transport and fate of carbon and nutrients in aquatic environments, particularly those of the coastal zone.  Central to this is an interest in how biological communities (primarily planktonic communities) respond to changing environmental conditions, be they natural or anthropogenic, and how this, in turn, affects the ecological functioning of both the biological community and integrated ecosystem.

While my work is motivated by an interest in understanding the large-scale, biogeochemical dynamics of aquatic ecosystems, much of my effort is spent investigating the smaller-scale mechanisms underlying such dynamics.  This requires an emphasis on the metabolic activities of the microbial community.  Earth is, and always has been, overwhelmingly dominated by microorganisms.  The metabolic activities of microorganisms are instrumental in shaping the distribution and global cycling of many biologically important elements, such as C, O, N and P.  Indeed, it is increasingly clear that the environmental factors regulating the growth and activity of these microbial communities (especially the bacterial community) are, in large part, those factors that regulate many of the essential functions of the ecosystem.  However, the specific nature of the environmental regulation of these microbial processes, and thus how the biogeochemical functioning of aquatic ecosystems will respond to large-scale climate and landscape changes remains poorly understood.  Much of my research involves addressing various aspects of this uncertainty.  In particular, two key areas of my research include: 1) the regulation of heterotrophic processes (especially that of respiration), and the nature of their coupling to autotrophic production, in determining the flows of energy and organic matter within and between ecosystems; and 2) the interaction of carbon and nutrient availability in regulating microbial metabolism and the fate of dissolved organic carbon, which is the largest reservoir of organic carbon in the global marine ecosystem.

As part of the North Inlet – Winyah Bay National Estuarine Research Reserve’s research and monitoring efforts, efforts are currently underway in my laboratory to examine the relationships between microbial metabolism and physiochemical conditions over tidal to (eventually) interannual time scales in these two estuaries.  The goal of this research is to improve our predictive understanding of water quality variability as well as its potential for long-term change due to increasing anthropogenic impact in the North Inlet and Winyah Bay watersheds.  In addition, microbial communities, because of their rapid generation times, react faster to environmental change than any other biotic component of the ecosystem.  Thus, this research is also aimed at developing the potential for measures of microbial metabolism to serve as highly sensitive and integrative ecological indicators for assessing short-term variability and long-term change in the ecological condition of these environments.  Initial efforts are focused on water column communities and processes.

Smith EM, Benner R (2005) Photochemical transformations of riverine dissolved organic matter: Effects on estuarine bacterial metabolism and nutrient demand. Aquatic Microbial Ecology 40:37-50  [pdf]

Hopkinson CS, Smith EM (2005) Chapter 8: Estuarine respiration: An overview of benthic, pelagic and whole system respiration. In PA del Giorgio and PJleB Williams (Eds.), Respiration in aquatic ecosystems. Oxford University Press. pp 123-147

Cammack WKL, Kalff J, Prairie YT, Smith EM (2004) Fluorescent dissolved organic matter in lakes: Relationships with heterotrophic metabolism. Limnology and Oceanography 49:2034-2045  [pdf]

Smith EM, Prairie YT (2004) Bacterial metabolism and growth efficiency in lakes: The importance of phosphorus availability. Limnology and Oceanography 49: 137-147  [pdf]

Smith EM, Kemp WM (2003) Planktonic and bacterial respiration along an estuarine gradient: responses to carbon and nutrient enrichment. Aquatic Microbial Ecology 30: 251-261  [pdf]

Smith EM, del Giorgio PA (2003) Low fractions of active bacteria in natural aquatic communities? Aquatic Microbial Ecology 31: 203-208  [pdf]

Lomas, MW, Glibert PM, Shiah F-K, Smith EM (2002) Microbial processes and temperature in Chesapeake Bay: Current relationships and potential impacts of regional warming. Global Change Biology 8: 51-70

Smith EM, Kemp WM. (2001) Size structure and the production/respiration balance in a coastal planktonic community. Limnology and Oceanography 46: 473-484. [pdf]  With errata 46: 1578.  [pdf]

Smith EM (1998) Coherence of microbial respiration rate and cell-specific bacterial activity in a coastal planktonic community. Aquatic Microbial Ecology 16: 27-35.

Kemp WM, Faganeli J, Puskaric S, Smith EM, Boynton WR (1999) Pelagic-benthic coupling and nutrient cycling. In: Malone TC, Smodlaka, Harding LH, Malej A (Eds.), Trends in Land-Use, Water Quality and Fisheries: A Comparison of the Northern Adriatic Sea and the Chesapeake Bay. Coastal and Estuarine Studies Series, AGU, Washington, D.C.

Hopkinson C, Buffam I, Hobbie J, Vallino J, Perdue M, Prahl F, Covert J, Hodson R, Moran M, Smith E, Baross J, Crump B, Findlay S, Forman K (1998) Terrestrial inputs of organic matter to coastal ecosystems: An intercomparison of chemical characteristics and bioavailability. Biogeochemistry 43: 211-234.

Kemp WM, Smith EM, Marvin-DiPasquale M, Boynton WR (1997) Organic carbon balance and net ecosystem metabolism in Chesapeake Bay. Marine Ecology Progress Series 150: 229-248.

Smith EM, Kemp WM (1995) Seasonal and regional variations in plankton community production and respiration for Chesapeake Bay. Marine Ecology Progress Series 103: 217-231