Exploring metapopulation-scale suppression alternatives for a global invader in a river network experiencing climate change

Invasive species can dramatically alter ecosystems, but eradication is difficult, and suppression is expensive once they are established. Uncertainties in the potential for expansion and impacts by an invader can lead to delayed and inadequate suppression, allowing for establishment. Metapopulation viability models can aid in planning strategies to improve responses to invaders and lessen invasive species’ impacts, which may be particularly important under climate change. We used a spatially explicit metapopulation viability model to explore suppression strategies for ecologically damaging invasive brown trout (Salmo trutta), established in the Colorado River and a tributary in Grand Canyon National Park. Our goals were to estimate the effectiveness of strategies targeting different life stages and subpopulations within a metapopulation; quantify the effectiveness of a rapid response to a new invasion relative to delaying action until establishment; and estimate whether future hydrology and temperature regimes related to climate change and reservoir management affect metapopulation viability and alter the optimal management response. Our models included scenarios targeting different life stages with spatially varying intensities of electrofishing, redd destruction, incentivized angler harvest, piscicides, and a weir. Quasi-extinction (QE) was obtainable only with metapopulation-wide suppression targeting multiple life stages. Brown trout population growth rates were most sensitive to changes in age 0 and large adult mortality. The duration of suppression needed to reach QE for a large established subpopulation was 12 years compared with 4 with a rapid response to a new invasion. Isolated subpopulations were vulnerable to suppression; however, connected tributary subpopulations enhanced metapopulation persistence by serving as climate refuges. Water shortages driving changes in reservoir storage and subsequent warming would cause brown trout declines, but metapopulation QE was achieved only through refocusing and increasing suppression. Our modeling approach improves understanding of invasive brown trout metapopulation dynamics, which could lead to more focused and effective invasive species suppression strategies and, ultimately, maintenance of populations of endemic fishes.     

Establishing and using study criteria to ensure the rigor and robustness of survival compliance testing at hydroelectric dams

An elaborate set of criteria have been developed by fish managers and regulators to assure the accuracy, precision, representativeness, and robustness of survival compliance studies coordinated within the Federal Columbia River Power System in the northwestern USA. Dam passage survival, defined as survival from the dam face to the tailrace mixing zone, must be ≥96 % for spring out migrating juvenile salmonids [i.e., yearling Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss)] and ≥93 % for summer outmigrants (i.e., subyearling Chinook salmon). Survival must be estimated with a standard error ≤1.5 %. However, these quantitative benchmarks are only part of a multifaceted set of criteria, including representative dam operations, river discharge levels, and fish selection, along with tests of model validity that must be satisfied. These criteria are illustrated using acoustic-tag survival compliance studies conducted at The Dalles Dam on the Columbia River, 2010–2012. The results suggest evaluation criteria for survival compliance tests must balance the needs for rigor and robustness with the ability to reasonably perform the tests in naturally varying riverine systems.     

Integrating Seasonal Information on Nutrients and Benthic Algal Biomass into Stream Water Quality Monitoring

Benthic chlorophyll a (BChl a) and environmental factors that influence algal biomass were measured monthly from February through October in 22 streams from three agricultural regions of the United States. At‐site maximum BChl a ranged from 14 to 406 mg/m² and generally varied with dissolved inorganic nitrogen (DIN): 8 out of 9 sites with at‐site median DIN >0.5 mg/L had maximum BChl a >100 mg/m². BChl a accrued and persisted at levels within 50% of at‐site maximum for only one to three months. No dominant seasonal pattern for algal biomass accrual was observed in any region. A linear model with DIN, water surface gradient, and velocity accounted for most of the cross‐site variation in maximum chlorophyll a (adjusted R² = 0.7), but was no better than a single value of DIN = 0.5 mg/L for distinguishing between low and high‐biomass sites. Studies of nutrient enrichment require multiple samples to estimate algal biomass with sufficient precision given the magnitude of temporal variability of algal biomass. An effective strategy for regional stream assessment of nutrient enrichment could be based on a relation between maximum BChl a and DIN based on repeat sampling at sites selected to represent a gradient in nutrients and application of the relation to a larger number of sites with synoptic nutrient information.     

Pairing Modern and Paleolimnological Approaches to Evaluate the Nutrient Status of Lakes in Upper Midwest National Parks

Understanding what constitutes a reference (background) nutrient condition for lakes is important for National Park Service managers responsible for preserving and protecting aquatic resources. For this study we characterize water quality conditions in 29 lakes across four national parks, and compare their nutrient status to U.S. Environmental Protection Agency (USEPA) nutrient reference criteria and alternative criteria recently proposed by others. Where appropriate we also compare the nutrient status of these 29 lakes to state or tribal nutrient reference criteria or standards. For lakes that exceed reference criteria we investigate physical and chemical patterns, and for a subset of lakes compare modern nutrient conditions to paleolimnological (i.e., diatom‐inferred [DI]) nutrient reconstructions. Many lakes exceeded USEPA nutrient reference criteria, but met alternative less restrictive criteria. Modern nutrient conditions were also largely consistent with DI historic (pre‐1900) nutrient conditions. Lakes exceeding alternative nutrient criteria and with elevated nutrient levels relative to DI historic conditions were mostly small, shallow, and dystrophic; continued attention to their nutrient dynamics and biological response is warranted. Coupling modern and paleolimnological data offer an innovative and scientifically defensible approach to understand long‐term nutrient trends and provide greater context for comparison with reference conditions.     

Power and politics of social–ecological regime shifts in the Chilika lagoon,India and Tam Giang lagoon,Vietnam

Analyses of ecological regime shifts primarily focus on abrupt, long-term and significant changes that trigger fundamental reorganisation in ecosystem structure and function. There remains limited empirical work on the relationship between regime shifts and social inequities, power imbalances, and social and environmental injustices. Inadequate attention to this social context restricts our ability to predict and avert impending regime shifts, or to effectively navigate where thresholds have been crossed. In this paper, we offer an initial empirical assessment of politics and power in two coastal lagoons in India and Vietnam experiencing abrupt change. We adopt a realist view of power to: (1) assess the social relations structuring human–environment interactions in both lagoons; (2) characterise the dominant framings and narratives that influence if and how regime shifts are understood; (3) consider who wins and loses if and when regime shifts and other forms of rapid environmental change take place; and (4) reflect on the implications of power and politics for the governance of regime shifts in linked human–ocean settings.     

Whose values count: is a theory of social choice for sustainability science possible?

If sustainability science is to mature as a discipline, it will be important for practitioners to discuss and eventually agree upon the fundamentals of the paradigm on which the new discipline is based. Since sustainability is fundamentally a normative assertion about tradeoffs among values, how society chooses the specifics among these tradeoffs is central to the sustainability problem. Whose values should count in making social decisions and how should the multiplicity of values that exist be known and used in that decision process? Given the vast spatial domains and temporal domains at work in the sustainability problem, we need some means of reconciling the inevitably divergent choices depending on whose values we count, how we know what those values are, and how we count them in making social decisions. We propose an approach to dealing with these questions based on Rawls (A theory of justice. Belknap Press, Cambridge, 1971) and explore the problems inherent in a social choice theory for sustainability science.     

Regional engagement and spatial modelling for natural resource management planning

Changing unsustainable natural resource use in agricultural landscapes is a complex social–ecological challenge that cannot be addressed through traditional reductionist science. More holistic and inclusive (or transdisciplinary) processes are needed. This paper describes a transdisciplinary project for natural resource management planning in two regions (Eyre Peninsula and South Australian Murray-Darling Basin) of southern Australia. With regional staff, we reviewed previous planning to gain an understanding of the processes used and to identify possible improvement in plan development and its operation. We then used an envisioning process to develop a value-rich narrative of regional aspirations to assist stakeholder engagement and inform the development of a land use management option assessment tool called the landscape futures analysis tool (LFAT). Finally, we undertook an assessment of the effectiveness of the process through semi-structured stakeholder interviews. The planning process review highlighted the opinion that the regional plans were not well informed by available science, that they lacked flexibility, and were only intermittently used after publication. The envisioning process identified shared values—generally described as a trust, language that is easily understood, wise use of resources, collaboration and inclusiveness. LFAT was designed to bring the best available science together in a form that would have use in planning, during community consultation and in assessing regional management operations. The LFAT provided spatially detailed but simple models of agricultural yields and incomes, plant biodiversity, weed distribution, and carbon sequestration associated with future combinations of climate, commodity and carbon prices, and costs of production. Stakeholders were impressed by the presentation and demonstration results of the software. While there was anecdotal evidence that the project provided learning opportunities and increased understanding of potential land use change associated with management options under global change, the direct evidence of influence in the updated regional plan was limited. This project had elements required for success in transdisciplinary research, but penetration seems limited. Contributing factors appear to be a complexity of climate effects with economic uncertainty, lack of having the project embedded in the plan revision process, limited continuity and capacity of end users and limited after project support and promotion. Strategies are required to minimise the controlling influence that these limitations can have.     

High‐Frequency Continuous Monitoring to Track Vapor Intrusion Resulting From Naturally Occurring Pressure Dynamics

Vapor intrusion characterization efforts can be challenging due to complexities associated with background indoor air constituents, preferential subsurface migration pathways, and response time and representativeness limitations associated with conventional low‐frequency monitoring methods. For sites experiencing trichloroethylene (TCE) vapor intrusion, the potential for acute risks poses additional challenges, as the need for rapid response to exposure exceedances becomes critical in order to minimize health risks and associated liabilities. Continuous monitoring platforms have been deployed to monitor indoor and subsurface concentrations of key volatile constituents, atmospheric pressure, and pressure differential conditions that can result in advective transport. These systems can be comprised of multiplexed laboratory‐grade analytical components integrated with telemetry and geographical information systems for automatically generating time‐stamped renderings of observations and time‐weighted averages through a cloud‐based data management platform. Integrated automatic alerting and responses can also be engaged within one minute of risk exceedance detection. The objectives at a site selected for testing included continuous monitoring of vapor concentrations and related surface and subsurface physical parameters to understand exposure risks over space and time and to evaluate potential mechanisms controlling risk dynamics which could then be used to design a long‐term risk reduction strategy. High‐frequency data collection, processing, and automated visualization efforts have resulted in greater understanding of natural processes such as dynamic contaminant vapor intrusion risk conditions potentially influenced by localized barometric pumping induced by temperature changes. For the selected site, temporal correlation was observed between dynamic indoor TCE vapor concentration, barometric pressure, and pressure differential. This correlation was observed with a predictable daily frequency even for very slight diurnal changes in barometric pressure and associated pressure differentials measured between subslab and indoor regimes and suggests that advective vapor transport and intrusion can result in elevated indoor TCE concentrations well above risk levels even with low‐to‐modest pressure differentials. This indicates that vapor intrusion can occur in response to diurnal pressure dynamics in coastal regions and suggests that similar natural phenomenon may control vapor intrusion dynamics in other regions, exhibiting similar pressure, geochemical, hydrogeologic, and climatic conditions. While dynamic indoor TCE concentrations have been observed in this coastal environment, questions remain regarding whether this hydrogeologic and climatic setting represent a special case, and how best to determine when continuous monitoring should be required to most appropriately minimize exposure durations as early as possible. ©2017 Wiley Periodicals, Inc.     

Erratum to: Estimating urban water demand under conditions of rapid growth: the case of Shanghai

Regional Environmental Change - Many of the world’s major cities are expected to face significant water shortages in coming decades, largely due to increased demand arising from economic and...