Aquatic ecosystems are sensitive to the modification of hydrologic regimes, experiencing declines in stream health as the streamflow regime is altered during urbanization. This study uses streamflow records to quantify the type and magnitude of hydrologic changes across urbanization gradients in nine U.S. cities (Atlanta, GA, Baltimore, MD, Boston, MA, Detroit, MI, Raleigh, NC, St. Paul, MN, Pittsburgh, PA, Phoenix, AZ, and Portland, OR) in two physiographic settings. Results indicate similar development trajectories among urbanization gradients, but heterogeneity in the type and magnitude of hydrologic responses to this apparently uniform urban pattern. Similar urban patterns did not confer similar hydrologic function. Study watersheds in landscapes with level slopes and high soil permeability had less frequent high-flow events, longer high-flow durations, lower flashiness response, and lower flow maxima compared to similarly developed watersheds in landscape with steep slopes and low soil permeability. Our results suggest that physical characteristics associated with level topography and high water-storage capacity buffer the severity of hydrologic changes associated with urbanization. Urbanization overlain upon a diverse set of physical templates creates multiple pathways toward hydrologic impairment; therefore, we caution against the use of the urban homogenization framework in examining geophysically dominated processes.

Consumption of added sugar has increased over recent decades and is correlated with numerous diseases. Rodent models have elucidated mechanisms of toxicity, but only at concentrations beyond typical human exposure. Here we show that comparatively low levels of added sugar consumption have substantial negative effects on mouse survival, competitive ability, and reproduction. Using Organismal Performance Assays (OPAs) – in which mice fed human-relevant concentrations of added sugar (25% Kcal from a mixture of fructose and glucose [F/G]) and control mice compete in seminatural enclosures for territories, resources and mates – we demonstrate that F/G-fed females experience a two-fold increase in mortality while F/G-fed males control 26% fewer territories and produce 25% less offspring. These findings represent the lowest level of sugar consumption shown to adversely affect mammalian health. Clinical defects of F/G-fed mice were decreased glucose clearance and increased fasting cholesterol. Our data highlight that physiological adversity can exist when clinical disruptions are minor, and suggest that OPAs represent a promising technique for unmasking negative effects of toxicants.

Many projects have been undertaken to restore urban rivers in arid regions. At the same time, passive discharge of urban water sources has stimulated redevelopment of wetlands and riparian forests along stretches of dewatered rivers. In Phoenix, Arizona, for example, some segments of the dewatered Salt River have been actively restored by planting and irrigation, whereas others have revegetated in response to runoff from storm drains and effluent drains. Our research documents how biotic communities differ between these actively restored and 'accidentally' restored areas, and between wetter and drier urban reaches. We addressed these objectives with a multi-taxa, multi-season sampling approach along reaches of the Salt River. We quantified plants using cover estimates in quadrats, birds using fixed radius, point-count surveys, and herpetofauna (amphibians and reptiles) using visual-encounter surveys. One notable finding was that wetland plants had greater richness and cover at accidentally restored sites compared with actively restored, dry urban, and non-urban reference sites. Birds and herpetofauna, however, were most species-rich at actively restored and non-urban reference sites, and riparian birds were more abundant at sites with perennial flows compared with ephemeral reaches. From a landscape perspective, the range of management approaches along the river (including laissez-faire) is sustaining a diverse riparian and wetland mosaic. Urban water subsidies are sustaining freshwater forests and marshlands, the latter a regionally declining ecosystem. In urbanized rivers of arid regions, mapping and conserving perennial stream flows arising from stormwater and effluent discharge can be an important complement to active restoration. Figure 2. Species accumulation curves for (A) vascular plants, (B) bird species, and (C) herpetofauna species along the Salt River in central Arizona. Plants were surveyed during the pre-monsoon dry season. Birds and herpetofauna were surveyed during warm seasons (March to September). 798 H. L. BATEMAN et al.Figure 5. Non-metric multidimensional scaling (NMDS) graph showing locations of seven vegetation sampling sites in each of two seasons (July and September). (A) NMDS axis 1 separates plant species (small dots) by flow permanence, and (B) NMDS axes 2 and 3 separate species by degree of urbanization. 802 H. L. BATEMAN et al.Figure 6. Non-metric multidimensional scaling (NMDS and SE ellipses) graphs for bird species (plotted as four-letter codes; Appendix 3) sampled among seven river reaches. (A) NMDS axis 1 separates bird species by season, with most waterfowl and marshland birds being abundant during winter (ellipses: fall is black, winter is grey, spring is grey dotted, and summer is black dotted). (B) NMDS axis 2 separates bird community by amount of flow, with urban dry sites most dissimilar to other reaches. 803 URBAN NOVEL WATER SOURCES

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