Alteration of streamflow magnitudes and potential ecological consequences: a multiregional assessment

Abstract

Human impacts on watershed hydrology are widespread in the US, but the prevalence and severity of stream‐flow alteration and its potential ecological consequences have not been quantified on a national scale. We assessed streamflow alteration at 2888 streamflow monitoring sites throughout the conterminous US. The magnitudes of mean annual (1980–2007) minimum and maximum streamflows were found to have been altered in 86% of assessed streams. The occurrence, type, and severity of streamflow alteration differed markedly between arid and wet climates. Biological assessments conducted on a subset of these streams showed that, relative to eight chemical and physical covariates, diminished flow magnitudes were the primary predictors of biological integrity for fish and macroinvertebrate communities. In addition, the likelihood of biological impairment doubled with increasing severity of diminished streamflows. Among streams with diminished flow magnitudes, increasingly common fish and macroinvertebrate taxa possessed traits characteristic of lake or pond habitats, including a preference for fine‐grained substrates and slow‐moving currents, as well as the ability to temporarily leave the aquatic environment.

Putting Flow–Ecology Relationships into Practice: A Decision-Support System to Assess Fish Community Response to Water-Management Scenarios

“…For example, differences in modeled streamflow across water-management scenarios were most apparent under low-flow conditions (Figure 3), suggesting that seasonal low flows in summer and early autumn represent a critically important context for evaluating ecological effects of water-management decisions [6,10]. In addition, pronounced spatial differences were apparent in response to water-management scenarios.…”

“…Human modifications to streamflow regimes-such as from impoundments, diversions, and water withdrawals-are globally widespread and escalating, especially in areas that experience highly variable natural flow regimes [4][5][6][7]. Because streamflow is a master variable in stream ecology, influencing physical habitat characteristics, water quality, biotic interactions, and energy inputs [8][9][10], flow alteration is a serious threat to riverine biodiversity [11,12].…”

“…Because streamflow is a master variable in stream ecology, influencing physical habitat characteristics, water quality, biotic interactions, and energy inputs [8][9][10], flow alteration is a serious threat to riverine biodiversity [11,12]. Literature reviews and regional assessments (e.g., [6,[13][14][15][16]) indicate a variety of ecological responses by aquatic biota to streamflow alteration, including changes in reproductive behavior, community shifts based on trophic strategy, reduced species richness, and in particular the loss of native and sensitive species.…”

Catalysis for Biomass and CO2 Use Through Solar Energy: Opening New Scenarios for a Sustainable and Low-Carbon Chemical Production

“…Replacing traditional annual cropping systems with switchgrass in the Midwest and High Plains may cause additional stress to water resources because the agricultural crop production in large portions of these areas (e.g., Kansas and Nebraska) is dependent upon irrigation water from already stressed local resources [21]. Streamflow volume (Q) is responsive to changes in both climate and land cover [22][23], and changes in Q have important biological and socioeconomic implications [24][25][26]. Anthropogenic alteration of Q has been shown to impair aquatic communities and ecosystems, and the likelihood of impairment rises rapidly with increasing severity of reduced Q [25].…”

“…Streamflow volume (Q) is responsive to changes in both climate and land cover [22][23], and changes in Q have important biological and socioeconomic implications [24][25][26]. Anthropogenic alteration of Q has been shown to impair aquatic communities and ecosystems, and the likelihood of impairment rises rapidly with increasing severity of reduced Q [25].…”