Science to support conservation action in a large river system:The Willamette River,Oregon,USA

Management and conservation efforts that support the recovery and protection of large rivers are daunting,reflecting the complexity of the challenge and extent of effort(in terms of policy,economic investment,and spatial extent)needed to afford measurable change.These large systems have generally experienced intensive development and regulation,compromising their capacity to respond to disturbances such as climate change orwildfire.Functionally,large river and basin management require insights gained from social,ecological,geophysical,and hydrological sciences.This multidisciplinary perspective can unveil the integrated relationship between a river network's biotic community and seasonally variableenvironmental conditions that are ofteninfluencedbyhumanactivities.Large rivers andtheir basins are constantly changing due to anthropogenic influences and as climate modifies patterns of temperature and precipitation.Because of these factors,the state of knowledge must advance to address changing conditions.The Willamette River,in western Oregon,USA,is a prime example of a basin that has experienced significant degradation and investment in rehabilitation in recent decades.Innovative science has facilitated development of fine-scale,spatially extensive datasets and models that can generate targeted conservation and rehabilitation actions that are prioritized across the entire river network.This prioritization allows investment decisions to be driven by site-specific conditions while simultaneously considering potentials for ecological improvement.Here,we review hydrologic,geomorphic,ecologic,and social conditions in the Willamette River basin through time—including pre-settlement,river development,andcontemporary periods—andoffer a futurevisionfor consideration.Currently,detailed informationaboutfish populations and habitat,hydrologic conditions,geomorphology,water quality,and land use can be leveraged to make informed decisions about protection,rehabilitation,and development.The time is ripe for strategic management and goal development for the entireWillamette River,and these efforts can be informed by comprehensive science realized through established institutions(e.g.,public agencies,non-profitwatershed groups,Tribes,and universities)focusedon conservation and management.The approaches to science and social-network creation that were pioneered in the Willamette River basin offer insights into thedevelopment of comprehensive conservation-based planning that could be implemented in other large river systems globally.

Agricultural water conservation in China:plastic mulch and traditional irrigation

Plastic mulch is commonly used with micro-irrigation in developed countries;however,Chinese farmers use plastic mulch on a vast scale independent of micro-irrigation.For the past three decades,China’s land area in plastic mulch has exceeded the world’s total land area in micro-irrigation.We report results from the water-scarce region of Minqin County,where 87%of Chinese farmers interviewed responded that they use plastic mulch to conserve water and 53%to increase yields.Survey results indicated the desire to conserve water through the use of plastic mulch to be statistically equivalent to the desire to increase yields.Responses to interviews and surveys indicate that farmers perceive water savings of 24-26%when plastic mulch is used.Interview and survey responses suggest farming families are shifting to purchasing wheat from outside the region;a potential import of"virtual water"into this water-scarce region.

Long-term phosphorus reduction and phytoplankton responses in an urban lake(USA)

Eutrophication is one of the primary factors causing harmful cyanobacteria blooms in freshwater lakes.This study investigated the long-term changes in water quality and summer phytoplankton assemblages in Oswego Lake,OR,USA,in relation to phosphorus reduction through hypolimnetic aeration and alum applications.Both water quality and phytoplankton assemblages were sampled biweekly during the summers from 2001 to 2013.The concentrations of total phosphorus,soluble reactive phosphorus,and total nitrogen decreased 66%,93%and 31%,respectively,in response to the hypolimnetic aeration and alum treatments since 2005.Summer phytoplankton assemblages showed a 62%reduction of cyanobacteria biovolume and a shift from cyanobacteria dominance(2001–2005)to diatom and chlorophyte dominance(2006–2013).Cluster analysis identified four statistically different groups of summer phytoplankton assemblages(denoted Groups 1–4).Nonmetric multidimensional scaling analysis indicated that the four groups were associated with different water quality conditions.Group 1 occurred prior to hypolimnetic aeration and was primarily comprised of cyanobacteria,associated with water conditions of high nutrients and high primary production.Group 2,dominated by cyanobacteria and chlorophytes,occurred between hypolimnetic aeration and alum surface application.Group 3 was dominated by diatoms and occurred after alum surface application.Group 4 included R-strategist phytoplankton that quickly respond to environmental changes and occurred in the years following alum injection,drawdown,and inflow alum treatment.Both Group 3 and 4 were associated with reduced nutrients in the lake.We conclude that these lake management practices had strong effects on both production and community compositions of phytoplankton,and advocate for future studies on large-scale climate impacts on lake ecosystems and to identify corresponding best management practices.