The evolving legacy of disturbance in stream ecology: concepts, contributions, and coming challenges

We reviewed the development of ideas and empirical understanding about disturbance in lotic ecosystems by providing a pre-1986 historic context and highlighting major themes that have emerged in the 25 y since the inception of J-NABS. Disturbance was not well incorporated into stream ecological thinking before 1986, but awareness of its significance began to emerge in the early 1980s, as demonstrated by the publication of several classic papers illustrating the ecological consequences of floods. Broad recognition of disturbance as a fundamental driver in streams was crystallized by Resh et al. (1988) in a paper that marked the beginning of a period of intense research on disturbance. We recognized 4 subsequent research themes: 1) definition of terms and concepts and development of tools for quantifying disturbances and ecological responses, 2) the disturbance renaissance, a period during which empirical research increased dramatically, 3) formalization of the significance of disturbance in streams by its incorporation into conceptual models of stream ecosystems, and 4) operationalization of disturbance for management and restoration of streams and rivers. Despite remarkable progress toward understanding disturbance in lotic ecosystems in the past 25 y, opportunities for future research are numerous. Increasing scope and intensity of human activities underscore the need to examine interactions among disturbances and to incorporate ecological principles into management and restoration activities. New insights are likely to arise from recognition of links between geomorphic forms and processes and the ecology of disturbance. Viewing streams in the context of regime shifts should also lead to new advances, particularly for restoration, because disturbances can elicit nonlinear responses. Successes in these efforts should contribute to improved scientific understanding and stewardship of streams and rivers.