energy flow in any type of ecosystem—an example of the leadership role that inland aquatic science has played in the earth and biological sciences. Energy transfer efficiency, relationships between production and decomposition, and physical-chemical constraints on biological production have been research topics in all types of aquatic ecosystems under this general theme. The importance of linkages between wetlands and lakes and between wetlands and streams with regard to carbon and energy flows (e.g., Wetzel, 1990) ties several major research thrusts together (e.g., biogeochemical cycling, especially carbon cycling, and ecosystem energetics), and it also could serve as a unifying theme for major subfields of limnology (i.e., lake, stream and wetland ecology).
Integrative paradigms are a much more recent development in lotic limnology7 than in lake limnology. This reflects the less integrated nature of the disciplines contributing to stream science. Indeed, until recently, the physical, chemical, and biological components of stream limnology could be characterized as a set of independent subdisciplines that were associated more with their parent basic-science disciplines than with limnology. For example, studies on the physical aspects of water flowing in streams are associated with the fields of hydrology and hydraulics, which are taught in engineering and geoscience departments. Hydrologists have their own professional organizations or separate divisions within major engineering societies (such as the American Society of Civil Engineering and the American Geophysical Union). Similarly, the origin and development of stream channels and drainage networks is a well-developed topic within the field of fluvial geomorphology, which is a subdiscipline of geography and (to a lesser extent) geology.
Until recently, chemical studies on flowing waters have been done primarily by geochemists, environmental engineers, and lake scientists interested in quantifying fluxes of minerals and pollutants from watersheds or into standing bodies of water (lakes and oceans). That is, stream chemistry has been of interest not so much as a subject of its own but as a means to answer questions about other natural systems. To an extent, this parallels the subservient role that chemistry played in sanitary (environmental) engineering before the 1960s.
For the most part, stream limnology has been identified most strongly with stream biology, but even here, practicing stream biologists often are identified more with other ''parent disciplines" such as public health biology (sanitary microbiology) and fisheries biology. Stream biology was