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The need to train sustainability scientists and engineers to address the complex problems of our world has never been more apparent. We organized an interdisciplinary team of instructors from universities in the states of Maine, New Hampshire, and Rhode Island who designed, taught, and assessed a multi-university course to develop the core competencies necessary for advancing sustainability solutions. Lessons from the course translate across sustainability contexts, but our specific focus was on the issues and trade-offs associated with dams. Dams provide numerous water, energy, and cultural services to society while exacting an ecological toll that disrupts the flow of water, fish, and sediment in rivers. Like many natural resource management challenges, effective dam decisions require collaboration among diverse stakeholders and disciplines. We linked key sustainability principles and practices related to interdisciplinarity, stakeholder engagement, and problem-solving to student learning outcomes that are generalizable beyond our dam-specific context. Students and instructors co-created class activities to build capacity for interdisciplinary collaboration and encourage student leadership and creativity. Assessment results show that students responded positively to activities related to stakeholder engagement and interdisciplinary collaboration, particularly when practicing nested discussion and intrapersonal reflection. These activities helped broaden students’ perspectives on sustainability problems and built greater capacity for constructive communication and student leadership.

The Tennessee Valley Authority (TVA) initiated a Reservoir Releases Improvement Program in 1991 to increase minimum flows and improve water quality by modifying its dam operations. We compiled a comprehensive data set from ecological monitoring below nine dams to evaluate the effects of these modifications on physicochemical conditions and benthic macroinvertebrate assemblages. Abiotic and biotic data were collected in tailwaters by the TVA for three dam operation \"treatments\" (i.e., before any modifications, following flow modifications, and following both flow and dissolved oxygen [DO] modifications) at three different stations (Upper, Middle, and Lower) located at increasing longitudinal distances below each dam. Analysis of variance was used to test for differences in ecological conditions among treatments and stations. Dam modifications had significant effects on both abiotic and biotic variables, and macroinvertebrate assemblages exhibited significant longitudinal differences. Yearly mean DO and mean minimum velocity increased following dam modifications. Across all sampling stations, macroinvertebrate family richness increased and the percentage of pollution-tolerant macroinvertebrates (% Tolerant) decreased after dam modifications. Family richness also increased, and % Tolerant decreased, with increasing distance below the dams. Total abundance of macroinvertebrates increased after flow modifications and then decreased following changes in DO. The percentage of individuals belonging to the orders Ephemeroptera, Plecoptera, and Trichoptera (% EPT) increased following flow and DO modifications, but only at the Upper station. EPT family richness was unaffected by increased flow alone but increased following increases in both flow and DO. The design of the reoperation \"experiment\" made it difficult to ascertain the relative contributions of flow and DO changes to the observed biotic responses, but flow alone appeared to have a smaller beneficial effect than the combined effects of flow and DO.

We were trained to do good science: to do our best to develop compelling research questions, to be unbiased about our data, skeptical about our conclusions, and open to criticism from our peers. We were also trained that good science was its own reward; that by pushing back the frontiers of knowledge, we were doing our part to make a better world. But as we progressed along our conventional academic pathways, we experienced a strong sense of cognitive dissonance: despite the production of more and better science, it often fell dramatically short of our hope to solve real-world problems and create a brighter future. Although we met other scientists who felt the same way, none of us knew how to chart a more productive path for doing science that makes a difference. So a group of us at our university set out on an adventure to see what we could do differently. Heres what we learned. We recognized in the University of Maine (UMaine), our small land-grant university in a state that is large in area but small in population, a potential model system to implement and evaluate faculty-led strategies for aligning research with societal needs. Although Maine faces many important challenges that could benefit from strategically aligned research, we focused on the challenges of sustainable economic and community development within the state. Many communities in Maine have strong connections to forestry, fisheries, agriculture, and outdoor recreation sectors that are experiencing rapid and unpredictable economic, social, and environmental changes. Given the multifaceted and interconnected nature of these challenges, we sought to learn whether interdisciplinary research teams could help identify causes and consequences of sustainability problems and develop and evaluate potential solutions. Along the way, we received a $20 million, five-year grant from the National Science Foundation that led to the creation of a permanent home for these efforts in 2014-the Senator George J. Mitchell Center for Sustainability Solutions-whose vision is to connect knowledge with action to create a brighter environmental, social and economic future in and beyond Maine. Our alignment strategy would require the development of strong collaborations with diverse stakeholders from the public and private sectors, nongovernmental organizations (NGOs), and civil society, because of their many roles in identifying problems and developing solutions. Fortunately, Maine is characterized by dense social networks where university faculty often have close relationships with important partners. Even when they dont, they frequently know someone who can help build those connections.

An ecological classification of dams is needed to characterize how the tremendous variation in the size, operational mode, age, and number of dams in a river basin influences the potential for restoring regulated rivers via dam removal. Dams vary tremendously in size and hence in their reservoir storage volume, factors that have very important direct and indirect environmental impacts.

Issue Title: Theme Advances in Algal Biology: A Commemoration of the Work of Rex Lowe We analyzed diatom and water chemistry data collected by The Academy of Natural Sciences from 47 rivers throughout the eastern United States to address several ecological questions. How does the composition of diatom assemblages vary over large regional scales? What are the most important environmental factors affecting assemblage composition and how does their influence vary among regions and with spatial scale? How do distributions and autecological characteristics of individual taxa vary spatially? What are the implications of answers to these questions for use of diatoms as water quality indicators? Data for 186 samples at 116 sites were collected from 1951 to 1991 on moderate- to large-sized rivers ranging from Maine to Texas as part of Academy monitoring and survey programs, most initiated and implemented by Dr. Ruth Patrick. Several sites were highly impaired by point and non-point source pollution. Diatom assemblages grouped into four main categories, based on multivariate analyses. Group membership correlated equally well with intermediate-scale geographic regions and water chemistry: (1) Northeastern US rivers with lower alkalinity and hardness, and pH 6.5-7.8; (2) Primarily dilute coastal plain rivers in the southeastern United States with the lowest average pH (5.5-7.3) of all sites and some with high DOC; (3) Rivers within and west of the Appalachian Mountains, generally having higher pH (>7.5) than those in other regions, but with relatively low chloride concentrations; and (4) Gulf Coast rivers with the highest chloride (>100 mg l^sup -1^), hardness (>250 mg l^sup -1^), and pH of rivers in all the groups. Hardness, pH, alkalinity, and Cl explained most of the variation among diatom assemblages, based on ordination analysis. Factors related to water quality problems, such as BOD, P, NH^sub 4^, and turbidity explained much less variability at the eastern US scale, but were more important in the four intermediate-scale regions. Diatom taxa abundance-weighted mean values for water chemistry characteristics varied among the four intermediate-scale regions, often greatly, and in proportion to the average measured values for each region. Design of calibration data sets for development of water quality indicators should account for spatial scale in relation to species dispersal, regional geochemistry and habitat types, and human-influenced water chemistry characteristics.[PUBLICATION ABSTRACT]

As the magnitude, complexity, and urgency of many sustainability problems increase, there is a growing need for universities to contribute more effectively to problem solving. Drawing upon prior research on social-ecological systems, knowledgeaction connections, and organizational innovation, we developed an integrated conceptual framework for strengthening the capacity of universities to help society understand and respond to a wide range of sustainability challenges. Based on experiences gained in creating the Senator George J. Mitchell Center for Sustainability Solutions (Mitchell Center), we tested this framework by evaluating the experiences of interdisciplinary research teams involved in place-based, solutions-oriented research projects at the scale of a single region (i.e., the state of Maine, USA). We employed a multiple-case-study approach examining the experiences of three interdisciplinary research teams working on tidal energy development, adaptation to climate change, and forest vulnerability to an invasive insect. Drawing upon documents, observations, interviews, and other data sources, three common patterns emerged across these cases that were associated with more effective problem-solving strategies. First, an emphasis on local places and short-term dynamics in social-ecological systems research provides more frequent opportunities for learning while doing. Second, iterative stakeholder engagement and inclusive forms of knowledge co-production can generate substantial returns on investment, especially when researchers are dedicated to a shared process of problem identification and they avoid framing solutions too narrowly. Although these practices are time consuming, they can be accelerated by leveraging existing stakeholder relationships. Third, efforts to mobilize interdisciplinary expertise and link knowledge with action are facilitated by an organizational culture that emphasizes mutual respect, adaptability, and solutions. Participation of faculty associated with interdisciplinary academic programs, solutions-oriented fields, and units with partnership-oriented missions hastens collaboration within teams and between teams and stakeholders. The Mitchell Center also created a risk-tolerant culture that encouraged organizational learning. Solutions-focused programs at other universities can potentially benefit from the lessons we learned.

Real and apparent conflicts between ecosystem and human needs for fresh water are contributing to the emergence of an alternative model for conducting river science around the world. The core of this new paradigm emphasizes the need to forge new partnerships between scientists and other stakeholders where shared ecological goals and river visions are developed, and the need for new experimental approaches to advance scientific understanding at the scales relevant to whole-river management. We identify four key elements required to make this model succeed: existing and planned water projects represent opportunities to conduct ecosystem-scale experiments through controlled river flow manipulations; more cooperative interactions among scientists, managers, and other stakeholders are critical; experimental results must be synthesized across studies to allow broader generalization; and new, innovative funding partnerships are needed to engage scientists and to broadly involve the government, the private sector, and NGOs.

We used hot-film anemometry to quantify fine-scale spatial and temporal flow variations near the surfaces of stones inhabited by suspension-feeding larval blackflies (Simulium vittatum). We focused especially on within-stone patterns of covariation between patchy microdistributions of larvae and local spatial variations in current speed. Current speeds were sampled at 256 Hz for heights between 1 and 10 mm above the bed. Profiles of current speed exhibited complex shapes, and boundary-layer thicknesses ranged from <1 to >5 mm. Average current speeds measured 2 mm above the bed (the approximate height of larval feeding appendages) ranged between 7 and 59 cm s-1. Current speeds measured 10 mm above the bed were very poor predictors of speeds measured at the 2-mm height. Larval abundance exhibited a significant positive relationship to current speed at 2-mm height, and within-stone variation in speed explained$\\ticksim 59%$of the variation in abundance. Times series of current speed exhibited marked fine-scale temporal heterogeneity, fluctuating by as much as$80 cm s^-1 in <0.1 s$. Maximum accelerations sometimes exceeded 1 × 104cm s-2, which suggests that the forces tending to dislodge benthic organisms from the bed may be greater than previous estimates based on assumptions of steady flow. Observed levels of turbulence were greater than predicted from traditional boundary-layer theory. We suggest that much of the turbulence evident on individual stones is not produced by local shear but is inherited from upstream roughness elements that cause flow separation.

We evaluate the effects of small dams (11 of 15 sites less than 4 m high) on downstream channels at 15 sites in Maryland and Pennsylvania by using a reach upstream of the reservoir at each site to represent the downstream reach before dam construction. A semi-quantitative geomorphic characterization demonstrates that upstream reaches occupy similar geomorphic settings as downstream reaches. Survey data indicate that dams have had no measurable influence on the water surface slope, width, and the percentages of exposed bedrock or boulders on the streambed. The median grain diameter (D50) is increased slightly by dam construction, but D50 remains within the pebble size class. The percentage of sand and silt and clay on the bed averages about 35% before dam construction, but typically decreases to around 20% after dam construction. The presence of the dam has therefore only influenced the fraction of finer-grained sediment on the bed, and has not caused other measurable changes in fluvial morphology. The absence of measurable geomorphic change from dam impacts is explicable given the extent of geologic control at these study sites. We speculate that potential changes that could have been induced by dam construction have been resisted by inerodible bedrock, relatively immobile boulders, well-vegetated and cohesive banks, and low rates of bed material supply and transport. If the dams of our study are removed, we argue that long-term changes (those that remain after a period of transient adjustment) will be limited to increases in the percentage of sand and silt and clay on the bed. Thus, dam removal in streams similar to those of our study area should not result in significant long-term geomorphic changes.