Hydrologic stress is increasing in Fremont cottonwood (Populus fremontii) forests across the southwestern United States because of increased temperature and streamflow diversion. The spatial variability of this stress is large yet poorly understood. Along the Yampa and Green Rivers in Colorado and Utah, vapour pressure deficit and flow diversions increase downstream. To investigate effects of this gradient on cottonwoods, we measured the percent live canopy and height of randomly selected trees at three sites: Deerlodge Park on the Yampa River (DLP), Island Park on the upper Green (ILP) and Canyonlands National Park on the lower Green (CAN). From these same trees, we took increment cores to understand differences in tree growth in each forest over time. We then related tree metrics to local water availability, streamflow and climatic data. Cottonwoods at CAN were shorter and had lower percent live canopy and growth rate than similarly aged trees upstream. CAN trees that grew higher above the water surface also tended to have lower tree growth, height and live canopy percentage. Furthermore, the correlation between tree growth and maximum vapour pressure deficit showed a much stronger negative shift since 1990 at CAN than at the other sites. All of these differences suggest higher hydrologic stress at CAN, which we attribute to the combined effects of peak flow declines from Flaming Gorge Reservoir, flow diversion and the higher and increasing vapour pressure deficit at CAN. Further research on the variability of hydrologic stress on cottonwoods could help managers anticipate and mitigate the effects of drought stress in these iconic forests.

Sediment eroded from the headwaters of a large basin strongly influences channels and ecosystems far downstream, but the connection is often difficult to trace. Disturbance‐dependent riparian trees are thought to rely primarily on floods for formation of the sand bars necessary for seedling establishment, but pulses of sediment should also promote formation of such features. In order to expand understanding of the role of sediment connectivity in governing ecological processes, here we explore the hypothesis that cottonwood forest along the Green and Yampa Rivers in Utah and Colorado are dominated by trees established a century ago during a period of extensive channel migration caused by significant headwater erosion. Analysis of historical documents and aerial photographs suggests that three key tributaries of the Yampa River underwent significant historical erosion from roughly 1880 to 1940. Average width and depth of tributaries with defined arroyos increased two to six times from historical surveys, resulting in the export of ~30 million metric tons of sediment, sizably increasing the sediment load and channel migration rate of the Yampa and Green Rivers. Establishment of major portions of several downstream cottonwood forests occurred during this period of historical erosion, increased sediment loads, and heightened channel migration rates, and the area of forest dating to that time is much greater than can be explained by high flows alone. Viewed collectively, our findings suggest tributary erosion played a vital role in successful downstream forest establishment, a link we contend is best illustrated through a sediment‐ecological connectivity framework. Broadly, this framework facilitates consideration of linkages between morphological and ecological processes at the watershed‐scale. Development and utilization of a watershed‐scale sediment‐ecological connectivity perspective highlights the value of sediment as a critical ecological resource to be managed jointly with flow to ensure the maintenance of vital riverine ecosystems.

Increasing demand for river water now conflicts with an increasing desire to maintain riparian ecosystems. Efficiently managing river flows for riparian vegetation requires an understanding of the time scale of flow effects, but this information is limited by the absence of long-term studies of vegetation change in response to flow variation. To investigate the influence of short- and long-term flow variability and dam operation on riparian vegetation, we determined the occurrence of 107 plant species in 133 permanent plots of known inundating discharge along the Gunnison River in Colorado on five different occasions between 1990 and 2013. Individual species moved up and down the gradient of inundating discharge coincident with increases and decreases in mean annual flow, and the correlations between flow and species occurrence were strongest when flows were weighted by time before vegetation sampling with a median half-life of 1.5 years. Some tall, rhizomatous, perennial species, however, responded to flows on a longer time scale. Logistic regression of species occurrence showed a significant relation with inundation duration for 70 out of 107 species. Plot species richness and total vegetative cover decreased in association with desiccation at low inundation durations and with fluvial disturbance at high inundation durations. Within-plot similarity in species occurrence between years decreased strongly with increasing inundation duration. Moderate inundation durations were dominated by tall, rhizomatous, perennial herbs, including invasive Phalaris arundinacea (reed canary grass). Over the 23-year study period, species richness declined, and the proportion of rhizomatous perennials increased, consistent with the hypothesis that decreases in flow peaks and increases in low flows caused by flow regulation have decreased establishment opportunities for disturbance-dependent species. In summary, annual-scale changes in vegetation were strongly influenced by flow variation, and decadal-scale changes were influenced by decreases in fluvial disturbance from upstream flow regulation beginning decades prior to the onset of this study.

Water-quality functions associated with bottomland hardwood ecosystems include 1) control of sediment detachment and transport, 2) sediment detention, and 3) nutrient and contaminant detention and transformation. Human activities that modify the various physical characteristics of bottomland hardwood ecosystems correspondingly affect the influence of these ecosystems on water quality. In general, water-quality functions associated with bottomland hardwoods are 412adversely affected by all human developmental activities because undeveloped stands provide optimal physical characteristics for improving water quality. Any activity resulting in flood control or conversion of bottomland hardwoods will have a negative effect on water-quality functions, particularly if best management practices or other mitigation measures are not included in the activity.

Deltas and backwater-affected bottomlands are forming along tributary and mainstem confluences in reservoirs worldwide. Emergence of prograding deltas, along with related upstream hydrogeomorphic changes to river bottomlands in the backwater fluctuation zones of reservoirs, signals the development of new and dynamic riparian and wetland habitats. This study was conducted along the regulated Missouri River, USA, to examine delta-backwater formation and describe vegetation response to its development and dynamics. Our research focused specifically on the delta-backwater forming at the confluence of the White River tributary and Lake Francis Case reservoir. Objectives of the research were to: (1) describe and analyze the process of delta-backwater formation over space and time; (2) determine by field sampling and GIS mapping how vegetation has responded to development of the delta-backwater; and (3) compare the woody plant communities of the delta-backwater to those along free-flowing and regulated remnant river reaches. In response to base level changes caused by reservoir filling, the thalweg of the lower 31 km of the original White River channel and adjacent floodplain aggraded by up to 12 m between 1954 and 2011. The overall channel slope flattened from 0.70 to 0.29 m/km. Riparian Populus-Salix forests increased in area by nearly 50% during the post-dam period by colonizing new deltaic and floodplain deposits. Many of the native woody species found along natural and regulated river reaches were also found on the delta-backwater. Woody species sorted along a fluvial to delta gradient; wetland affiliated species (Salix spp., Typha spp.) dominated the delta-backwater near the reservoir while riparian species (Populus, Fraxinus) dominated in upstream portions of the delta-backwater. This habitat complex supports young stands of native riparian vegetation now in decline in remnant reaches protected from flooding.

In 2011, a large, long‐duration flood occurred on the regulated Missouri River following six decades without flooding. This study evaluated the effects of the flood on riparian forest structure and composition. In 2012, 168 forest sites sampled in 2006–2009 were resampled on five floodplain segments between Montana and Missouri, with 80 sampled again in 2013–2014. Changes in riparian forest area over 2006–2012, by age class and segment, were assessed using aerial imagery and GIS. Repeated‐measures analysis of variance was used to examine (a) the initial effects of the flood (preflood to 2012) on tree and shrub stem densities, (b) postflood (2012–2014) changes in stem density, and (c) species‐level responses for cottonwood ( Populus deltoides ), eastern red cedar ( Juniperus virginiana ), and Russian olive ( Elaeagnus angustifolia ). Across the study area, forest area declined 6–38% among age classes, with the greatest declines in the youngest classes. Tree density declined 19–49% across segments from preflood to 2012 but did not change significantly from 2012 to 2014. Shrub density declined 52–89% across segments from preflood to 2012, with 73–78% declines in the two youngest age classes, but increased by 42% from 2012 to 2014. Cottonwood and Russian olive, but not red cedar, showed partial recovery in the shrub/sapling layer, increasing from 2012 to 2014. Although flooding is important for floodplain forest health, the 2011 flood had mixed effects, with significant mortality of native floodplain trees and shrubs and only limited cottonwood recruitment. The initial decline in invasive species (Russian olive and red cedar), however, suggests that flooding may be an effective management tool.

The threat of mass extinctions as a consequence of global warming joins a growing list of assaults on planetary biodiversity. The intensive collecting carried out by the Bureau of Biological Survey in the late nineteenth and early twentieth centuries forms much of the basis for our current understanding of plant and animal distribution. Existing descriptions of habitat relationships were used to predict the presence or absence of native terrestrial vertebrates in vegetation cover type. The greatest challenge facing wildlife management agencies today is recognition of the need for long-range planning for nongame wildlife species and the community and ecosystem diversity represented in their habitats. The opportunity to maintain national biodiversity through changes in management prescriptions on public lands exists primarily in the west. Through cooperation with private land owners and conservation groups, a set of Biodiversity management areas, coupled with selected endangered species reserves, could stem future extinctions in the region and serve as a model for international planning.

Zika virus (ZIKV), which can cause devastating disease in fetuses of infected pregnant women, can be transmitted by mosquito inoculation and sexual routes. Little is known about immune protection against sexually transmitted ZIKV. In this study, we show that previous infection through intravaginal or subcutaneous routes with a contemporary Brazilian strain of ZIKV can protect against subsequent intravaginal challenge with a homologous strain. Both routes of inoculation induced high titers of ZIKV-specific and neutralizing antibody in serum and the vaginal lumen. Virus-specific T cells were recruited to and retained in the female reproductive tract after intravaginal and subcutaneous ZIKV infection. Studies in mice with genetic or acquired deficiencies in B and/or T cells demonstrated that both lymphocyte populations redundantly protect against intravaginal challenge in ZIKV-immune animals. Passive transfer of ZIKV-immune IgG or T cells significantly limited intravaginal infection of naive mice, although antibody more effectively prevented dissemination throughout the reproductive tract. Collectively, our experiments begin to establish the immune correlates of protection against intravaginal ZIKV infection, which should inform vaccination strategies in nonpregnant and pregnant women. IMPORTANCE The recent ZIKV epidemic resulted in devastating outcomes in fetuses and may affect reproductive health. Unlike other flaviviruses, ZIKV can be spread by sexual contact as well as a mosquito vector. While previous studies have identified correlates of protection for mosquito-mediated infection, few have focused on immunity against sexual transmission. As exposure to ZIKV via mosquito bite has likely occurred to many living in areas where ZIKV is endemic, our study addresses whether this route of infection can protect against subsequent sexual exposure. We demonstrate that subcutaneous ZIKV infection can protect against subsequent vaginal infection by generating both local antiviral T cell and antibody responses. Our research begins to define the immune correlates of protection for ZIKV infection in the vagina and provides a foundation for testing ZIKV vaccines against sexual transmission.

Along rivers, native and invasive species may establish and persist on active channel bedforms as part of channel narrowing. Using historical aerial photography and dendrochronology, we quantified spatial and temporal patterns of narrowing and vegetation expansion, including native Fremont cottonwood (Populus fremontii) and non‐native Russian olive (Elaeagnus angustifolia), along the largely unregulated Escalante River in south‐western United States. Russian olive establishment was examined with respect to hydrologic and climate variables. Narrowing along the Escalante River was initiated during a mid‐20th century drought. Cottonwood rapidly colonized higher, bar surfaces between the 1950s and 1981. Small numbers of Russian olive established in moist sites during this period as the channel narrowed by nearly 80%. After 1981, there was no obvious cottonwood establishment but low channel bars and banks were rapidly colonized by Russian olive. Hydroclimate predictors were equivocal but exponential growth of this large‐seeded, shade‐tolerant species lagged its introduction by 30 years, apparently because of delayed reproductive maturity, limited seed availability, and widespread availability of favourable establishment sites following initial channel narrowing. Sediment trapping, levee formation, and modification of channel form by dense, channel‐edge bands of Russian olive progressively limited new establishment sites and by 2000, recruitment declined sharply. Our results have implications for management of non‐native tree invasions along arid‐region rivers, including identification of low, moist, active channel bars where the establishment and physical impacts of Russian olive appear to be most pronounced and where focused management efforts are likely to be most effective.

Category: Basic Sciences/Biologics, Lesser Toes, Midfoot/Forefoot Introduction/Purpose: Hammertoes, crossover toes, and claw toes are common deformities and can be a major source of pain and dysfunction. These deformities result from instability of the metatarsophalangeal (MTP) joint due to incompetence of the plantar plate and/or collateral ligaments. Non-operative management is the first line of treatment. When non-operative treatment is unsuccessful, surgical interventions have been described. Newer surgical techniques focus on performing anatomic repairs of plantar plates. The vasculature of the foot has been well studied, but the vascular supply of the plantar plate has not been described. This study presents a new technique for imaging the microvasculature of the lesser toe plantar plates through micro- computed tomography (micro-CT) in order to better understand tear pathology and the capacity of healing with plantar plate repairs. Methods: The posterior tibial and dorsalis pedis arteries of a fresh frozen human cadaver foot were dissected and cannulated at the ankle for perfusion distally. After administration of an anticoagulant, each artery was perfused with Microfil® Silicone Rubber, a contrast agent. The compound was then allowed to cure, and the foot was fixed in formalin. The foot was sectioned through the metatarsal shafts for imaging, and imaging of the lesser toe MTP joints was performed using a Bruker Skyscan 1176 micro-CT scanner at 18 micron slices. Computerized reconstruction of the images was performed for three dimensional visualization of the vasculature. Results: Post-perfusion imaging of the lesser toe MTP joints using micro-CT allows for visualization of the plantar plate microvasculature. Preliminary imaging suggests that micro-CT is a useful modality for analysis of the blood supply of the plantar plate. Conclusion: Anatomic repair of the plantar plate has become a viable treatment option for MTP joint instability. One important question that remains to be answered is whether plantar plate tears have the capacity to heal. We present a novel technique for imaging of lesser toe plantar plate microvascularity using micro-CT. Preliminary results of post-perfusion imaging of the plantar plate are promising for developing a better understanding of its blood supply. Further definition of the plantar plate vascular supply will help clinicians understand the capacity for healing after repairs and may provide some insight to the biological causes plantar plate tears.

The functional trait framework, an ecological tool powerful for its simplicity and ability to facilitate modeling and generalization across environmental gradients, can capture the interactions between ecological and physical processes that shape riparian ecosystems. We demonstrate that ecological-response traits that describe how a plant will respond to abiotic stressors are similar, or strongly correlated, to morphological-effect traits important for determining how a plant alters the flow of water and transport of sediment. This link allows for modeling the distribution of ecological and morphological traits on the basis of environmental conditions. Observations of the topographic response of vegetated plots to moderate flood events illustrate how plant traits can be linked to landform geometry. As such, the functional trait framework provides a modeling approach to understand the coupled dynamics of ecogeomorphic systems and inform their conservation.

Hawai‘i has lost more than half of its endemic avifauna. Causes have varied, but habitat loss, hunting, predation by introduced predators, and disease are those for which we have the best evidence. With the exception of actions taken on behalf of birds in the Leeward Islands, the scale of management actions has not matched the scale of the threats. Species like the ‘Akiapola‘au (Hemignathus munroi), ‘Akepa (Loxops coccineus), Palila (Loxioides bailleui), and Po‘ouli (Melamprosops phaeosoma) are threatened over their entire range. Despite this, management actions are typically limited to areas less than 1% of species ranges. In the absence of any near future means to eliminate avian diseases, the survival of Hawai‘i’s endemic avifauna depends on elimination of habitat modifiers such as feral cattle (Bos taurus), pigs (Sus scrofa), goats (Cupra hircus), feral sheep (Ovis aries), and mouflon (&is musimon). Introduced predators such as cats (Felis catcts), rats (Rattus spp.), feral dogs (Canis ,familiaris), and small Indian mongoose (Herpesfes auropuncfatus) must be eliminated or significantly reduced in numbers over all, or a significant part of, the ranges of the threatened and endangered species of the islands. Failure to do so will result in all but two or three of the commonest species becoming extinct.

A study of arroyo evolution in northern New Mexico (Friedman and others, 2015) assessed geomorphic change in the Chaco Wash arroyo from the 1930s to 2000. As part of this study, in October 2000 a trench was excavated across the arroyo bottom and a high-precision (Real-time kinematic) GPS survey was conducted. GPS survey data were used to georeference a 1930s topographic map and to identify key geomorphic features, including the tops of the arroyo walls and the channel thalweg. Linear features were mapped in a GIS for use in extracting channel thalweg profiles, an arroyo cross section, and arroyo widths (1930s and 2000) as a function of distance down-valley. These features have been converted to shapefiles included in the set of mapped features. Results from analyses using these data were presented in: Friedman, J.M., Vincent, K.R., Griffin, E.R., Scott, M.L., Shafroth, P.B., and Auble, G.T., 2015, Processes of arroyo filling in northern New Mexico, USA, GSA Bulletin, 127(3/4), 621-640. doi: 10.1130/B31046.1