John L. Sabo, Ph.D. - US grants

Collaborative Research: Food-Chain Length in Streams-Testing the Role of Ecosystem Size, Resource Availability and Disturbance.
Sabo, John L.
Arizona State University
A critical determinant of community structure and ecosystem function is food-chain length, a measure of the number of times energy and materials are transferred from the bottom to the top of a food web. Food-chain length affects community structure by altering trophic interactions, influences ecosystem functions, and, in part, determines the concentration of contaminants in top predators, including many fish that humans eat. Food-chain length is also strongly affected by human activities through, e.g., harvesting activities and habitat fragmentation. Despite the central place of food-chain length in ecology, relatively little is known about the factors controlling this fundamental food web property. This project focuses on how ecosystem size, resource availability and disturbance govern food-chain length in food webs found in river ecosystems. To address this question, the project will compare data collected from 40+ rivers across North America, using existing data sets as well as making new field measurements and applying stable isotope techniques to estimate food-chain length. A deeper understanding of food-chain length in streams will help elucidate the complex linkages between ongoing and accelerating human environmental changes on important societal concerns such as contaminant concentrations, biodiversity, and carbon cycling. This project will support the collaboration of three new faculty members during the crucial early phase of their careers, train a postdoctoral fellow, one graduate student, and several undergraduates in cross-disciplinary research, and conduct a hands on K-12 outreach effort in local high schools using stream food webs as a tool for representing ecological complexity and for teaching an appreciation of the importance of biodiversity.

Water table lowering is a common problem in arid regions of the world such as deserts. One consequence of water table lowering is a change in the abundance and number of species (called "species diversity") of plants in habitats along river margins (called "riparian" habitats). While much is known about the effects of water table lowering on plants, little is known about how the relative availability or access to ground water may affect the abundance and diversity of animals in riparian habitats. The goals of this project are twofold: (1) to develop new tools to quantify the flow of water from sub-surface (groundwater) and surface (river) sources to animal populations and, (2) to use these tools to quantify water limitation in animal species occupying desert riparian habitats along the San Pedro River in southeastern Arizona. The tools we will develop will be based on traditional applications of stable isotopes of hydrogen (2H, or D, for "deuterium") and oxygen (18O) to trace water sources from the environment through plants. Stable isotopes are naturally occurring, non-radioactive elements with higher mass than the more common, lighter versions of these elements (1H and 16O, respectively). We will use differences in naturally occurring concentrations of these stable isotopes in leaves and in river water to understand the indirect acquisition of water by animals via consumption of plant material. To do this we will focus primarily on invertebrates feeding on dead organic matter and their predators. This study system will allow us to determine the pathways by which water flows through trees from groundwater to animals inhabiting above-ground habitats.

This research will achieve broader impacts by training two graduate students and by establishing the basis for applying stable isotopes of hydrogen and oxygen to the management of groundwater resources.

Urbanization is the most rapidly increasing land use type worldwide. We already know that biodiversity is radically altered in cities. However, we do not know what factors control the trophic or feeding structure of urban communities, and how these controls differ from less human-dominated or natural environments. For example, reduction of predators in cities could mean that herbivores (consumers of plants) increase dramatically and are controlled only by resources or stress. Our research will determine the relative effects of resources, stress, and natural enemies (predator and parasites) in cities on herbivore and predator abundances and diversity, and plant biomass.

Our research addresses fundamental questions - How is trophic structure and dynamics influenced by urbanization and, are trophic dynamics different in cities than in less human dominated ecosystems? This research will provide insights into how food webs and their associated biodiversity and ecosystem services can be maintained in urban settings. This research is closely linked to educational and K-12 outreach programs (e.g., Ecology Explorers), as well as partnerships with state and local governments and businesses. Some of our experimental sites are K-12 schoolyards, where K-12 teachers and students will directly participate in the experiments and interact with ASU faculty and graduate students.

Alterations and reductions of river flow have resulted in drastic changes to streamside areas of the Western US and throughout much of the world. Effects of these changes on plants have been documented, but effects on communities of land animals are less known. The degree to which animals rely on river water versus water from moist food may help predict how river alteration will affect streamside communities. Isotopes of water that are non-radioactive and occur naturally throughout the globe may be used to document the relative importance of these two possible water sources to animals. However, this technique is complicated by a change in water isotopes in the animal, over time, due to differences in evaporation between heavier and lighter isotopes. The proposed research will investigate a technique to avoid problems created by this phenomenon, using laboratory experiments on representative animal species.

The ability to use isotopes to document patterns of animal water use would be a great asset to biologists globally, especially those studying drylands, river and streamside areas, irrigated landscapes, and the effects of climate change. This project will incorporate undergraduate and K-12 students from diverse backgrounds, providing them with first-hand experience with scientific research.

Intellectual Merit

"The year 2011 will mark the 25th anniversary of the publication of Cadillac Desert: The American West and Its Disappearing Water (1986, Penguin Books). In this book Reisner dissects the politics, economics and ecological folly of large water projects in the American West and suggests that Western (US) civilization as we know it will collapse due to ailing water management"sedimentation within large reservoirs, water shortages in urban areas and soil salinity reclaimed agricultural bread baskets. Much of Reisner's evidence is journalistic (e.g., expert opinion). We seek funding for a pair of workshops aimed at identifying the appropriate scientific data and analytical tools necessary for rigorously evaluating Reisner's journalistic apocalypses.
Specifically, we will convene two organizational workshops in which we accomplish two goals: 1) collating data & identifying rigorous analytic approaches that would contribute to a regional synthesis of the hydrologic, geomorphic, economic, agricultural and ecological health of large Western water projects, and 2) writing a policy forum piece summarizing existing datasets"and most importantly identifying data gaps and research needs to complete this regional synthesis. This planning workshop will be held at the National Center for Ecological Analysis & Synthesis, and will form the basis for future working groups at the National Center for Ecological Analysis & Synthesis and the incipient John Wesley Powell Center for Integrated Science (an incipient USGS think tank being designed in the spirit of NCEAS). Our roster of workshop participants includes hydrologists, geologists, ecologists, agricultural scientists, economists and lawyers (see Roster below). Thus, we hope to develop an agenda for the proposed regional synthesis with input from multiple fields of science and policy.
Broader Impacts"The planned workshops would lead to synthesis of publicly accessible databases that could be used in future analyses of the broad scale impacts of reclamation in the Western US.
B-

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

Because climate and water are intimately linked in deserts, desert streams are well suited for observing consequences of both natural climate variability and human-caused climate change. Here, researchers propose to study how stream ecosystem structure changes as variable frequency and magnitude of both flash floods and drought periods over many years cause losses or gains in the abundance of wetland plants. A shift in stream ecosystem structure to dominance by wetland plants affects ecological functions in important but undocumented ways. Both the causes and consequences of this shift will be assessed by surveying structure, monitoring stream chemistry, comparing wetland with unvegetated stream reaches during recovery following winter-spring flooding, and statistically analyzing hydrology-ecosystem relationships. An interdisciplinary team will reevaluate stream ecosystem models and test new models using long-term data from this and other streams.

This research will promote synthesis of long-term data from aridland streams and advance understanding of these ecosystems in ways that can contribute to the general theory of stability of multiple ecosystem states. A distributed graduate seminar will give students experience with use of long-term databases and foster collaborative interactions. The database for this well-known stream ecosystem will be extended to more than 35 years and made available to the scientific and management community, potentially informing management in a highly variable environment where stressors of climate change and population growth are converging.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

Water and energy are essential ingredients of life and key commodities for humans and other living organisms that make up food webs. Curiously, although the role of energy in determining the inner workings of food webs has been thoroughly explored, water has been mostly ignored in food web ecology. The goal of this project is to fill this critical research gap by working to understand how the balance between supply and demand of energy and water affects patterns of abundance and biodiversity in terrestrial food webs. The research will involve a combination of large scale field experiments, stable isotopic tracers, and measurements of the metabolism and water use of individual animals. The research will be conducted in the forest ecosystem neighboring the San Pedro River, one of the last free flowing and perennial rivers in the Desert Southwest (USA). Arid lands occupy 1/3 of the Earth's terrestrial surface and drought is prevalent even in mesic and humid biomes. Thus, results from this project should provide general guidance for conservation planners about how changes in local energy and water balance associated with climate change will alter biodiversity in terrestrial ecosystems.

The research will involve K-12 outreach and education to enhance science curricula in schools in rural areas. This will be accomplished through a novel collaboration between graduate students and K-12 teachers as well as a web-based monitoring of river flows on the San Pedro River.

The Mekong River is one of the largest river systems on earth, and supports one of the most biologically diverse aquatic ecosystems in the world. The Tonle Sap Lake on the Mekong River is one of the most productive freshwater fisheries in the world. Seasonally inundated during the flood season of the Mekong, the flood waters of the Mekong fill the Tonle Sap basin. The fisheries associated with the Tonle Sap and its flood pulse ecology provide the majority of the protein for several million people in Cambodia. Despite the global ecological significance of the Tonle Sap and the regional importance of the fishery, scientific knowledge of the ecology of the ecosystem and of the processes underlying its productivity is rudimentary. The life histories of most fish species in the system have not been documented, data on foodweb relationships are almost entirely lacking and the basic processes sustaining the incredible productivity of the system are unknown.

This workshop will bring together a working group to develop a research plan and modeling effort to provide the baseline ecological understanding and the development of local research capacity through provision of needed scientific infrastructure and the training of new scientists. The working group will focus on ecological research for the Tonle Sap, designed to gather data fundamental to sound management before the system is unrecognizably altered by climate change, upstream developments and intensive fisheries. A secondary focus of the workshop will be a working group to focus on Tonle Sap Foodweb Modeling. The plan will integrate the PEER-funded research of Veasna Kum and collaborators. This workshop will achieve broader impacts by providing a research plan, developing a consortium of research partners (international and peer), and by training and capacity-building to complement the PEER award to Dr. Kum.

1204368/1204396/1204478
Sankarasubraman Arumugam/ John Kominoski/ John Sabo
North Carolina State University/University of Georgia Research Foundation Inc./Arizona State University

Water resource availability varies across the Sunbelt of the United States with a sharp East-West transition at 105 degrees W. Arid regions west of the 105th Meridian produce less runoff compared to humid regions in the East that produce greater than 40 cm of mean annual runoff. Consequently, reservoirs in the West are over-year systems holding multiple years of inflows, whereas reservoirs in the East are within-year storage systems with the need to refill the system in the beginning of spring. Accordingly, water policies also differ substantially with western states pursuing ("prior appropriation") and the eastern states following ("riparian rights") for allocation. These contrasting strategies also impact freshwater biodiversity with the ratio of non-native to native fish species being nearly 6 times higher in the West compared to the East. In spite of these cross-regional differences, both regions face two common stressors: (a) uncertainty in available freshwater arising from global climate change and (b) increased human demand due to population growth and consumption. Consequently, there is an ever-increasing need for an integrated assessment of freshwater sustainability under these two stressors over the planning horizon (10-30 years). The main objective of this study is to understand and quantify the potential impacts of near-term climate change and population growth on freshwater sustainability - defined here as integrating daily to annual flows required to minimize human vulnerability and maximize ecosystem needs (including native biodiversity) for freshwater - by explicitly incorporating the feedbacks from human-environmental systems on water supply and demand in various target basins spanning Arizona to North Carolina. Using retro-analyses involving AR5 multimodel climate change hindcasts, we will revisit how freshwater sustainability could have been better achieved over the past five decades across the Sunbelt. To couple the hydroclimatic and hydro-ecological system dynamics with the management of freshwater infrastructure systems, a two-level agent-based modeling framework will explicitly simulate adaptive behaviors and feedbacks between policy and consumers.

This interdisciplinary project will involve collaboration among three universities, North Carolina State University (NCSU), Arizona State University (ASU), and University of Georgia (UGA). Findings from the AR5 retro-analyses will evaluate and recommend societal options (i.e., supply augmentation vs. demand reduction) for promoting future (2015-2034) freshwater sustainability across the Sunbelt. Cross-regional synthesis of policies and media sources for the targeted basins will identify de-centralized adaptive strategies that have been employed independently and collectively to maintain flows, increase supplies, or reduce demands. Utilizing the near-term hydroclimatic projections, PIs will quantify how current policies on reservoir operations and groundwater extraction could impact the reliability of future water supplies for cities and also alter the key attributes of hydrographs that are critical for maintaining freshwater biodiversity. In doing so, the project will also investigate the degree to which regions have pursued "hard path" (i.e., supply augmentation) vs. "soft path" (i.e., demand reduction) strategies by explicitly modeling potential societal interventions for freshwater sustainability. The educational goal of the project is to conduct an online distributed seminar in which Honors, MS and PhD students from three Universities with interdisciplinary backgrounds will produce a policy-oriented white paper based on the key findings. Based on the white paper, the project team will distribute a suite of podcasts on freshwater sustainability and climate change to middle and high school science programs from the targeted basin states as well as to key water policy institutions across the region. Podcasts, developed data, tools and publications will also be disseminated through the main project portal at NCSU, and additionally through the National Climate Assessment and ASU's Central Arizona - Phoenix LTER websites.

The pattern of water flow in a river can affect the abundance of plants and animals and the food web that supports fisheries. Severe floods that scour the riverbed can potentially displace or kill plants and animals, however, little is known about how floods (or droughts) or the timing of these across years affects the complexity and diversity of food webs. Some work suggests that river flow is a stronger determinant than the quantity of plant production on the flow of energy through the food web, but little is known about how the quality of plant food affects food chains and biodiversity. The study will provide fundamental information on how the timing of floods and droughts across years influences water quality (nitrate inputs to rivers), primary production, and the production of animals higher in the food web, such as fish. The researchers will produce a synthesis of research in hydrology and ecology to improve the management of arid land rivers. This work will reach across fundamental knowledge to education, from kindergarten to graduate levels. The project will have numerous broader impacts including training of several undergraduates, graduate students, and a postdoc. Researchers will work with a non-profit group to integrate project findings into an existing citizen science program on river drying sponsored by The Nature Conservancy, and develop an environmental education program for grades K-5. Finally, the research team will establish an innovative open source, distributed graduate seminar on application of statistical methods in ecology.

Researchers will study streams spanning a gradient in the timing of rainfall to examine the role of changing hydrologic regimes in altering nitrogen supply, energy supply and food web structure in arid land streams. This proposal will: 1) Quantify the effect of food quality, energy supply and energetic efficiencies on trophic structure, 2) Quantify the effects of time between floods on stimulation of plant production and trophic structure, and 3) Quantify the effect of changes in flow regime on trophic structure via direct mortality, shifts in plants at the base of the food web, and the structure of the food web. Proposed research activities include characterization of the hydrologic regime, analysis of food webs across a hydroclimate gradient, and manipulation of nitrogen supply. Extreme event statistics and spectral analyses will characterize properties of flood intervals and flow regime shifts across 12 study sites spanning a gradient in timing of rainfall and hydrologic variation (monsoon vs. winter precipitation dominance) in Arizona. Derived hydrologic metrics will be used in combination with measures of ecosystem metabolism, N supply, secondary consumer energetic efficiencies, resource stoichiometry, and the proportion of autochthonous energy sources as predictor variables of food chain length and trophic structure to understand the mechanisms linking energetics and hydrology to food chain length. This comparative study includes 12 streams within the same biogeographic province that feature an algal-dominated food source and similar ecosystem size (1st-3rd order streams). Additionally researchers will conduct a nitrogen enrichment experiment in 6 streams to disentangle the indirect effects of water flow on nitrogen cycling versus the direct effects on plants and animals.

The Arizona State University will convene a workshop to advance an operational, national-scale definition of food-energy-water (FEW) systems complexity and outline a portfolio of basic research questions and programs needed to improve efficiency and resilience across the components of the FEW systems on the local and national scale. The workshop will create new synthetic knowledge that will contribute to the definition of necessary research programs. Workshop activities will provide a platform for collaboration and the creation of new teams to pursue research across the food-energy-water challenge area. Participants include faculty from universities in EPSCoR states and from minority serving institutions such that workshop activities will strengthen science and technology opportunities on these campuses.


The Food-Energy-Water (FEW) nexus is a rich area for basic research in sustainability science that would harness and synthesize insights from multiple fields, including complex systems, materials science, hydrology, civil, electrical and environmental engineering, computation and social science. The nexus contains myriad components covering technology, infrastructure or institutions that need to be included in any problem resolution. The 3-day workshop on the ASU campus will host approximately 60 attendees from multiple universities, national labs, and federal/state agencies. The goal is to invite a balance of participants representing food, water and energy with expertise in a mix of subjects including infrastructure, environmental engineering and institutions. This workshop will advance an operational, national-scale definition of FEW systems and outline research challenges that contribute to improved efficiency and resilience of national and regional FEW systems.

River and wetland ecosystems provide important ecosystem services that are determined by climate, such as water for human uses and habitat support for fish and wildlife. In southwestern deserts of the United States, years of extreme drought often follow years of very wet conditions, thus it is impossible to define river ecosystem services in terms of average conditions. In fact, high variability is an apt descriptor of the hydrologic regimes for streams in this region. In this project, researchers are using new statistical techniques that describe hydrological regimes, coupled with long-term measurements of stream structure and processes, to understand how shifts in climate and river discharge regimes on many time scales will influence the ecosystem. The research will focus on factors that explain why the abundance and distribution of wetland plants and the degree of nitrogen limitation vary dramatically among years. Also, the variation among years in patterns of change after spring floods - in primary production, nutrient retention, and community composition (of invertebrates and plants)- will be related to within- and among-year variation in hydrology, to determine the impact of regimes on these successional patterns. Finally, an interdisciplinary team of collaborators will reevaluate stream ecosystem models and test new models using long-term data from this and other desert streams.

This research will advance synthesis of long-term data from desert streams and advance understanding in ways that can contribute to the general theory of stability of multiple ecosystem states. A graduate student-led workshop will give students experience in using long-term databases and foster collaborative interactions. Activities of a collaboratory will expand the coupling of innovative hydrologic time-series analyses with ecological data. The database for this well-known stream ecosystem will be extended to more than 40 years and made available to the scientific and management community, potentially informing management in a highly variable environment where stressors of climate change and population growth are converging.

Scientists, along with the public and private sectors, are abuzz with the potential for "green infrastructure," an approach for water management that protects, restores, or mimics the natural water cycle. This approach is economical: Wetland construction or restoration can be far more cost effective than building a new water treatment plant. Green infrastructure also lessens manufacturing risks, while it enhances community safety and quality of life. For example, restored wetlands would improve water reliability for manufacturers, create habitats and open spaces for wildlife, and dampen the risks of drought and floods on public water supplies. The big, unanswered question about green infrastructure is whether managers would be better able to control water systems if green infrastructure was coupled with traditional gray infrastructure, such as reservoir operations. Modeling, data, and decision-support tools for blending gray and green water infrastructure, however, do not yet exist. This Critical Resilient Interdependent Infrastructure Systems and Processes (CRISP) project advances a modelling framework that couples gray and green water infrastructure systems and processes. The project also incorporate the effects of economically motivated human players into the coupled system. Specifically, this collaboration of scientists and water managers aims to minimize the impacts of extreme weather (drought and flood) on infrastructure processes in the chemical, petroleum, and agricultural sectors along the coastal basins of Texas. This work leads to: (1) A knowledge exchange between water-rights holders and regulators, including between private and public-sector actors. (2) An online learning platform to disseminate project results into curricula to train corporate sustainability officers and river authorities. (3) Training at least three graduate students, three postdocs, and many undergraduate students, including some from a minority-serving institution (Texas A&M University at Kingsville), and nurturing the collaboration between Arizona State and Texas A&M at Kingsville Universities.

The big, unanswered question about green infrastructure is whether the benefits - improved base flow reliability, damped peak flows, local storage - might be better controlled by being coupled to traditional gray infrastructure, such as reservoir operations. Modeling, data, and decision-support tools for blending gray and green water infrastructure do not exist at present. This project advances a control-theory framework that couples gray and green infrastructure subsystems and processes, and explicitly incorporates the effects of economically motivated human players into the system. The project framework minimizes the negative effects of extreme weather (drought and flood) on infrastructure processes in the chemical, petroleum, and agricultural sectors of the coastal basins of Texas. The work includes an integrated analysis of grey infrastructure for water storage and conveyance along with green infrastructure that provides environmental and aesthetic benefits. Although gray and green infrastructure are often intermingled, they are usually analyzed independently. For this integrated analysis, the engineering component is a model of ground and surface water interactions in both arid and humid regions in Texas. The computer science aspect is a synthesis of coupled grey-green infrastructure systems and the generation of environmental service flows. The socioeconomic study is an application of competitive game theory that seeks to understand and augment water trading to promote in-stream flows from water rights that have been allocated for commercial, industrial, or municipal use. The project also includes visualization and stakeholder engagement in the application of water trading.

This INFEWS project will identify and communicate science-based resource management constraints to sustain food-energy-water systems in the lower Mekong River Basin (MRB). The Mekong is one of the last major rivers to remain undammed for much of its length. The river's strong natural flood pulse is driven by the South Asian Summer Monsoon and controls multiple ecosystem processes critical to livelihoods in the region. Yet, despite the dominant role floodplain ecosystems play in the region, there is little known in the MRB regarding climate, hydrology, ecological processes, resource users and governance. Annual flooding controls the fluxes of the key nutrients and contaminants that enhance or shrink the growth and productivity of fish and rice. In this way, the flood pulse is directly linked to human well-being. However, the river's enormous discharge could also generate over 40 GW of power. This power is viewed as essential to stimulate the economic development of the region. It seems certain that future hydropower development and climate variability will impact the flood-pulse and the goods and services it provides in the MRB. To fill these knowledge gaps, this project(a partnership between Arizona State University and the University of Washington) will build analytical frameworks, collect critical field data, and construct new tools that advance the progress of science and that are also applicable for scenario analysis and planning as an aid to sustainable development and that will also promote the progress of science. Furthermore, food, energy and water security are core components of stability throughout the developing world, and this project will advance national security by providing science-based guidelines for stabilizing food-energy-water security tradeoffs in rapidly developing and growing regions of the world.

The South Mekong Livelihoods Project (SMLP) will provide a quantitative framework for predicting the effects of hydropower development and climate variability on the Mekong River Basin (MRB) and its flood-pulse, freshwater biodiversity, and both yields and nutritional quality of fish and rice, two key aspects of food security. The Variable Infiltration Capacity (VIC) macro-hydrology model will predict current and future streamflow and thereby serve as the foundation of the quantitative framework. VIC will be parameterized with new remote-sensing analyses predicting evapotranspiration as well as land-cover change from riparian forest to irrigated rice paddy. Climate simulations and future dam development and operations scenarios will be used as a forcing function for VIC, which will then drive a water-resources development model, a hydropower generation model, and a hydrodynamics model of the Tonle Sap Lake in the lower MRB. The project will link aspects of hydrology with food production in the Tonle Sap in two ways: 1) via multivariate autoregressive state-space analyses of new catch per unit effort data to quantify how timing, magnitude, and the decadal-scale sequence of the flood-pulse drives relative fish abundance and ecosystem processes; and 2) via a crop model (CropSyst) linked to VIC that generates rice yields from a physically based land-surface scheme. Dynamics of the flood-pulse are also likely to control food quality, specifically fluxes of key nutrients and harmful contaminants to people in fish and rice through its effect on redox biogeochemistry. The project will establish this relationship for the first time and incorporate both positive (nutritional) and negative (contaminants) effects of fish and rice into a single metric, thereby quantitatively linking the flood-pulse to human well-being. The research team will use metrics of food-system yield and quality to identify best management practices for dam development and operations using multi-objective optimization approaches that analyze tradeoffs between hydropower generation and food yield. Finally, the project will develop one of the first quantitative institutional analyses using a cooperative game-theoretic approaches to unearth best practices in creating international coalitions at multiple scales of governance. These system components will be integrated by measuring robustness of tradeoffs under climate extremes and given bargaining among institutions that might force local solutions to diverge from the global (basin) optima. The project will: 1) train three US-based postdoctoral researchers, six graduate students, multiple undergraduates, and at least two Cambodian students; 2) share critical data and models through broad stakeholder engagement within the Mekong; 3) develop a novel online curriculum that enhances STEM capacity in sustainability by engaging 20 fisheries managers in quantitative modeling and tradeoff analysis led by ASU's EdPlus online learning program; and 4) improve scientific capacity in the region as MRB scientists develop and apply the project's advanced modeling systems. Local scientists and students will be trained in both field and statistical methods so that the research can be sustained beyond the project's duration.