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3349685 
Book/Book Chapter 
The serial discontinuity concept of lotic ecosystems 
Ward, JV; Stanford, JA 
1983 
Ann Arbor Science 
Ann Arbor, MI 
Dynamics of Lotic Ecosystems 
29-42 
Recent theoretical concepts of lotic ecosystems deal primarily with origins and fates of organic resources and inorganic nutrients as prescribed by the stream continuum and nutrient spiraling concepts. These concepts are based on gradient analysis in which stream systems are, of necessity, viewed as uninterrupted continua. Few riverine ecosystems, however, remain free-flowing over their entire course. Rather, regulation by dams has typically resulted in an alternating series of lentic and lotic reaches. The serial discontinuity concept is an attempt to attain a broad theoretical perspective of regulated lotic ecosystems. Discontinuity distance (DD), defined as the longitudinal shift of a given parameter by stream regulation, may be positive (downstream shift), negative (upstream shift), or near zero . The direction and intensity of DD vary as functions or the specific parameter examined and the position of the dam(s) along the longitudinal stream profile. The serial discontinuity concept can be applied to physical parameters (e.g .. temperature summation) and biological phenomena at the population (e.g .. species abundance patterns), community (e.g .. biotic diversity), or ecosystem levels (e.g ., Photosynthesis; Respiration). Regulated streams, according to the serial discontinuity concept, are viewed as large-scale experimental systems in which disruptions in continuum processes and nutrient spirals create conditions amenable to testing and developing basic theories of stream ecology. 
Bartell, SM; Fontaine, TD 
978-0250406128