/ An extensive review of the published literature identified more than 150 case studies in which some aspect of resilience in freshwater systems was reported. Approximately 79% of systems studied were Iotic and the remainder lentic. Most of the stressor types were chemical with DDT (N = 29) and rotenone (N = 15) the most common. The most common nonchemical stressors were logging activity (N = 16), flooding (N = 8), dredging (N = 3), and drought (N = 7).The variety of endpoints to which recovery could be measured ranged from sparse data for phytoplankton (N = 13), periphyton (N = 6), and macrophytes (N = 8) to relatively more data for fish (N = 412) and macroinvertebrates (N = 698). Unfortunately the same characteristics were rarely measured consistently among sites. For example, with respect to fish, more than 30 different species were studied and recovery was measured in many ways, most commonly on the basis of: (1) first reappearance of the species, (2) return time of predisturbance densities, and (3) return time of predisturbance average individual size. Based on these criteria, all systems in these studies seem to be resilient to most disturbances with most recovery times being less than three years. Exceptions included when (1) the disturbance resulted in physical alteration of the existing habitat, (2) residual pollutants remained in the system, or (3) the system was isolated and recolonization was suppressed.The inherent capacity of an aquatic system to recover naturally from a stressor has been a neglected consideration in environmental assessments (Cairns 1978(Cairns , 1980. Primary reasons for this neglect are a lack of appreciation for the importance of recovery of an aquatic system following exposure to a stressor, and the lack of predisturbance data to properly assess whether a system has recovered. Most ecological research has focused on understanding how various stressors alter the chemical, physical, and biological function and structure of aquatic ecosystems. Once the effects are documented, funding generally has not been available to continue long-term studies of these systems (Likens 1983). Long-term studies of natural ecosystems are likely the only vehicle by which the recovery phase of a system can be understood.The lack of an appreciation for understanding the

ABSTRACT/To evaluate the relative effect of autecologic factors, site-specific factors, disturbance characteristics, and community structure on the recovery of temperate-stream fish communities, we reviewed case histories for 49 sites and recorded data on 411 recovery end points. Most data were derived from studies of low-gradient third-or fourth-order temperate streams located in forested or agricultural watersheds. Species composition, species richness, and total density all recovered within one year for over 70% ot systems studied. Lotic fish communities were not resilient to press disturbances (e.g., mining, logging, channelization) in the absence of mitigation efforts (recovery time >5 to >52 yr) and in these cases recovery was limited by habitat quality. Following pulse disturbances, autecological factors, site-specific factors, and disturbance-specific factors all affected rates of recovery. Centrarchids and minnows were most resilient to disturbance, while salmonid populations were least resilient of all families considered. Species within rock-substrate/nest-spawning guilds required significantly longer time periods to either recolonize or reestablish predisturbance population densities than did species within other reproductive guilds. Recovery was enhanced by the presence of refugia but was delayed by barriers to migration, especially when source populations for recolonization were relatively distant. Median population recovery times for systems in which disturbances occurred during or immediately prior to spawning were significantly less than median recovery times for systems in which disturbances occurred immediately after spawning. There was little evidence for the influence of biotic interactions on recovery rates.While studies of the effect of natural and anthropogenie disturbances on fish populations are common, relatively few studies examine the recovery of fish populations and communities (Niemi and others 1990). Data on recovery rates of aquatic communities are necessary not only for establishing exceedance criteria for water quality standards (Platkin 1988), but also for testing current ecological theory (Resh and others 1988, Yount and. Theories concerning the role of biotic versus abiotic control of fish communities (Schoener 1987), the role of succession in streams (Fisher 1983), island biogeugraphy theory (Minshall and others 1983), life history strategies, zoogeographical constraints, the effects of euvironmenud wiriability, and the effect of food web complexity on the stability of fish communities (Horwi~ 1978, DeAngelis and others 1989, Poff and Ward 1990, Reice and others 1990 are all relevant to the study of recovery processes. In this study, we review case ifistories containing data orl iish recovery rates in temperate streams and explore the KEY WORDS: Fish; Recovery; Disturbance; Stream; Communities *Author to whom corres|xmdence should be addressed. application of theories of community ecology to these data.Early studies of the recovery process in streams considered only featu...

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