Made available through Montana State University's ScholarWorks 2543 DECEMBER 2017 AMERICAN METEOROLOGICAL SOCIETY | THE RISING RISK OF DROUGHT. Droughts of the twenty-first century are characterized by hotter temperatures, longer duration, and greater spatial extent, and are increasingly exacerbated by human demands for water. This situation increases the vulnerability of ecosystems to drought, including a rise in drought-driven tree mortality globally (Allen et al. 2015) and anticipated ecosystem transformations from one state to another-for example, forest to a shrubland (Jiang et al. 2013). When a drought drives changes within ecosystems, there can be a ripple effect through human communities that depend on those ecosystems for critical goods and services (Millar and Stephenson 2015). For example, the "Millennium Drought" in Australia caused unanticipated losses to key services provided by hydrological ecosystems in the Murray-Darling basin-including air quality regulation, waste treatment, erosion prevention, and recreation. The costs of these losses exceeded AUD $800 million, as resources were spent to replace these services and adapt to new drought-impacted ecosystems (Banerjee et al. 2013). Despite the high costs to both nature and people, current drought research, management, and policy perspectives often fail to evaluate how drought affects ecosystems and the "natural capital" they provide to human communities. Integrating these human and natural dimensions of drought is an essential step toward addressing the rising risk of drought in the twenty-first century.Part of the problem is that existing drought definitions describing meteorological drought impacts (agricultural, hydrological, and socioeconomic) view drought through a human-centric lens and do not fully address the ecological dimensions of drought.

dAvian influenza (AI) virus can remain infectious in water for months, and virus-contaminated surface water is considered to be a source of infection within wild waterfowl populations. Previous work has characterized the effects of pH, salinity, and temperature on viral persistence in water, but most of that work was done with modified distilled water. The objective of this study was to identify the abiotic factors that influence the duration of AI virus persistence in natural surface water. Surface water samples were collected from 38 waterfowl habitats distributed across the United States. Samples were submitted to the U.S. Geological Survey National Water Quality Laboratory for chemical analysis and the University of Georgia for viral reduction time analysis. Samples were filtered with 0.22-m filters, and the durations of persistence of three wild-bird-derived influenza A viruses within each water sample at 10, 17, and 28°C were determined. The effects of the surface water physicochemical factors on the duration of AI viral persistence in laboratory experiments were evaluated by multivariable linear regression with robust standard errors. The duration of AI virus persistence was determined to be longest in filtered surface water with a low temperature (<17°C), a neutral-to-basic pH (7.0 to 8.5), low salinity (<0.5 ppt), and a low ammonia concentration (<0.5 mg/liter). Our results also highlighted potential strain-related variation in the stability of AI virus in surface water. These results bring us closer to being able to predict the duration of AI virus persistence in surface water of waterfowl habitats. Wild birds are considered to be the primordial reservoir for influenza A virus, with species within the orders Anseriformes and Charadriiformes having the largest and most diverse genetic pool of viruses (1, 2). Within these wild bird hosts, replication of avian influenza (AI) virus occurs primarily in the epithelial cells of the intestinal tract, and large amounts of virus are shed in feces (3, 4). The virus contaminates the surrounding aquatic environment, where it remains infectious, facilitating indirect transmission between birds (5-8). Environmental persistence of AI virus has been determined to be important for the epidemiology of the virus within wild bird populations and within aquatic habitats, and surface water is considered to be the major site of environmental contamination (9-12).The persistence of AI virus in water has been confirmed through environmental surveillance and laboratory-based investigations (6, 13-16). The temperature, pH, and salinity of the water have been identified as important determinants of the duration of persistence (8,(15)(16)(17)(18)(19). Using modified distilled water as a laboratory model, Brown et al. (16) determined that AI viruses are most stable in water with a neutral-to-basic pH (7.4 to 8.2), low salinity (Ͻ20 ppt), and a low temperature (Ͻ17°C). These general trends are supported by further laboratory investigations using natural surface water samples (8,15,1...

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and the nondestructive nature of its water content measurement as compared with conventional gravimetric

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