Active projects examine the microbial transformations of contaminants and trophic transfer of energy through microorganisms. A main line of inquiry deals with bacteria in the subsurfce (groundwater) environment. Current projects include field and laboratory investigations of hydrological factors controlling the transient removal of agricultural nitrate in sediments of low-relief coastal streams, and the role of autotrophic microbes in the dissolution of carbonates in submerged caves. Close collaboration with physical scientists (hydrologists, geochemists) is an important part of research in microbial ecology of the surface and subsurface. An additional line of research examines spatial relationships within microbial communities with respect how that structure determines the fulfillment of the microbe’s role in the ecosystem. Phenomena such as redundancy, congeneric homotaxis, stability, and resiliency are examined in model ecosystems that simulate natural microbial habitats to exploit microbial processes for renovation of domestic wastewater.