Humanity’s ever-increasing ability to effect environmental change on a number of spatial and temporal scales requires tough decisions about how we view, value, manage ecosystems. For example, advances in agriculture that support vastly more people per unit area than hunting gathering are clearly positive outcome for society. However, many beneficial land-use practices, including agriculture, may ultimately degrade To function as society, some amount ecosystem alteration must occur the human...

Nonlinear ecological responses to anthropogenic forcing are common, and in some cases, the ecosystem responds by assuming a new stable state. This article is an overview serves as introduction several articles this BRIDGES cluster that directed toward managers interested dealing with nonlinear freshwaters, particularly streams. A threshold or breakpoint occurs where system rapidly relatively small change driver. The existence of can signal configuration alternative state, although such does...

Streams collect runoff, heat, and sediment from their watersheds, making them highly vulnerable to anthropogenic disturbances such as urbanization climate change. Forecasting the effects of these using process-based models is critical identifying form magnitude likely impacts. Here, we integrate a new biotic model with four previously developed physical (downscaled projections, stream hydrology, geomorphology, water temperature) predict how fish growth reproduction will most probably respond...

Large woody debris (LWD) was added as an experimental stream restoration technique in two streams southwest Virginia. Additions were designed to compare human judgement log placements against a randomized design and unmanipulated reach, also effectiveness low- high-gradient stream. Pool area increased 146% the systematic placement 32% random sections of low-gradient stream, lending support notion that can be more effective than placing logs at streams. Conversely, changed very little after...

Urbanization is associated with substantial losses to stream biological diversity throughout the United States' mid‐Atlantic. Stream restoration has been used improve conditions and, in part, ameliorate these losses. However, relationship between and recovery of unclear. Our objective was critically examine efficacy urban restorations regard diversity. We compared restored streams nonrestored, nonurban, reference (minimally degraded) using five measures each fish benthic macroinvertebrate...

We examined the prognosis for long-term persistence of isolated populations cutthroat trout Oncorhynchus clarki and feasibility using barriers to protect them from nonnative salmonids. In so doing, we estimated minimum stream lengths (MSL) required by varying abundances rates population loss emigration mortality. Using 2,500 individuals (>75 mm) as target size—corresponding an effective size, Ne, 500—we that more than 8 km were maintain a with high fish (0.3 fish/m), 25 low abundance (0.1...

We used mark–recapture, radiotelemetry, and two-way traps to determine daily, seasonal, annual movements of cutthroat trout Oncorhynchus clarki in Beaver Creek, Idaho–Utah. recaptured 26 167 (16%) passive integrated transponder (PIT)-tagged trout; 16 the fish were less than 300 m from point capture 1 year earlier, whereas 10 a median 1,407 (range 331–3,292 m) their captured previous year. Radio-tagged individuals moved frequently shorter distances (median = 0 during autumn winter, more...

Abstract We examined the influence of landscape alteration and in situ stream habitat variables on brook trout Salvelinus fontinalis by using a landscape‐scale, space‐for‐time substitution analysis smaller data set that tracked long‐term changes land use over time. Forested cover within catchment was overall best landscape‐scale predictor occurrence at given site; measures impervious urbanization were also important predictors. Brook almost never found watersheds where exceeded 4%, as...

Lookingbill, T. R., S. Kaushal, A. J. Elmore, R. Gardner, K. N. Eshleman, H. Hilderbrand, P. Morgan, W. Boynton, M. Palmer, and C. Dennison. 2009. Altered ecological flows blur boundaries in urbanizing watersheds. Ecology Society 14(2): 10. https://doi.org/10.5751/ES-02989-140210

Ecological thresholds have much potential as a tool to use for watershed management. Not all systems exhibit abrupt nonlinear responses, but the threshold concept is still useful describing stressor responses or changes in state variables. For example, minimum detectable negative response an initiation-of-impact that might allow planning and management before population-scale change occurs taxa. An extirpation threshold, which point where system loses vital component, such species function,...

Urban development substantially alters the physicochemistry of streams, resulting in biodiversity and ecosystem function loss. However, interregional comparisons physicochemical impact urban streams suggest that geoclimatic heterogeneity may influence extent degradation. In Mid-Atlantic United States, adjacent Coastal Plain Piedmont physiographic provinces possess distinctly different hydrogeomorphic properties how stream ecosystems respond to urbanization. Recent bioassessments have...

Log length exerted a critical influence in stabilizing large woody debris (LWD) pieces added as an experimental stream restoration technique. Logs longer than the average bank-full channel width (5.5 m) were significantly less likely to be displaced logs shorter this width. The longest log stable groups was unstable groups. distances moved by demonstrated quadratic relationship associated with length; often, but they farther when entrained current majority of mobile smaller logs. stability...

We collected invertebrate drift samples and stomach contents of native Bonneville cutthroat trout Oncorhynchus clarki utah nonnative brook Salvelinus fontinalis in Beaver Creek, Idaho, during August 1995 to assess food availability the potential for competition. Regardless whether came from beaver pond or high-gradient low-gradient reaches, aquatic Diptera numerically dominated drifting invertebrates by at least fivefold over all other categories captured 1-h samples. Abundances densities...

Many interior populations of cutthroat trout Oncorhynchus clarki are at increased risk for extinction because small population size and the limited length habitable streams. Further, many these streams cannot be altered to provide adequate conditions persistence. I constructed a stage-based stochastic matrix model (1) evaluate reintroduction strategies capable restoration (2) feasibility maintaining through periodic supplemental stocking. In general, stocking adults reduced more than did...

Bat mortality caused by terrestrial wind-power plants has been documented and offshore developments may have similar effects. Determining which bat species occur offshore, how far they range from shore, predictors of high activity be helpful to developers wildlife managers. We studied off the mid-Atlantic coast, using ultrasonic detectors mounted on ships in spring fall 2009 2010. investigated association between nightly weather variables, including wind speed, air temperature, barometric...

Stream ecosystems are frequently impacted by changes in watershed land use, resulting altered hydrology, increased pollutant and nutrient loads, habitat degradation. Macroinvertebrates fish strongly affected stream conditions commonly used biotic indices to assess ecosystem health. Similarly, microbes respond environmental stressors, community composition alter key processes. The response of degradation their role global biogeochemical cycles provide an opportunity use as a monitoring tool....

Abstract There is evidence that actively moving salmonids are of lower condition than the general population, and they sometimes regarded as inferior to resident fish. However, little information exists on permanence this attribute. We used mark–recapture two‐way traps determine whether there differences in growth mobile Bonneville cutthroat trout Oncorhynchus clarki utah Beaver Creek, Idaho. Actively fish were significantly larger largest these for a given size. marked recaptured year later...

Abstract Although the American eel Anguilla rostrata occurs in a variety of habitats over large geographic areas, little is known regarding specific habitat relations that regulate distribution and abundance freshwater streams. We evaluated importance 17 physical habitat, chemical, biological variables predicting density five major river basins Maryland. Because artificial structures impede migration all basins, only sites determined to be on unblocked streams or downstream significantly...

Abstract The majority of interior subspecies cutthroat trout Oncorhynchus clarkii have been extirpated from large rivers by anthropogenic activities that fragmented habitats and introduced nonnative competitors. Selective pressures against migratory behaviors main‐stem river occupation, coupled with conservation strategies isolate genetically pure populations above barriers, restricted gene flow prevented expression the fluvial life history in many populations. Existing knowledge about...