Excess nutrients from agriculture in the Mississippi River drainage, USA have degraded water quality in freshwaters and contributed to anoxic conditions in downstream estuaries. Consequently, water quality is a significant concern associated with conversion of lands to bioenergy production. This study focused on the Arkansas‐White‐Red river basin ( AWR ), one of five major river basins draining to the Mississippi River. The AWR has a strong precipitation gradient from east to west, and advanced cellulosic feedstocks are projected to become economically feasible within normal‐to‐wet areas of the region. In this study, we used large‐scale watershed modeling to identify areas along this precipitation gradient with potential for improving water quality. We compared simulated water quality in rivers draining projected future landscapes with and without cellulosic bioenergy for two future years, 2022 and 2030 with an assumed farmgate price of $50 per dry ton. Changes in simulated water quantity and quality under future bioenergy scenarios varied among subbasins and years. Median water yield, nutrient loadings, and sediment yield decreased by 2030. Median concentrations of nutrients also decreased, but suspended sediment, which is influenced by decreased flow and in‐stream processes, increased. Spatially, decreased loadings prevailed in the transitional ecotone between 97° and 100° longitude, where switchgrass, Panicum virgatum L ., is projected to compete against alternative crops and land uses at $50 per dry ton. We conclude that this region contains areas that hold promise for sustainable bioenergy production in terms of both economic feasibility and water quality protection.

•Historical aerial photos allow reconstruction of land use history at a Gulf Coast site.•Land cover change has been synchronized by the lumber boom of the early 20th century.•A cycle of short-rotation forestry is imposed on the longer cycle of regrowth.•A wave-front of urban expansion has been replaced by a pattern of nucleation.•Modern land cover is dictated by proximity to an urban area rather than by regional trends.

Hydrokinetic energy is proposed as an environmentally preferred means of generating electricity from river and tidal currents. To resolve environmental concerns, it is important to investigate potential effects on aquatic organisms from the electromagnetic fields (EMFs) that are created by underwater generators and transmission cables. We evaluated the behavioral responses of some representative freshwater fishes to static and variable EMFs in a series of laboratory experiments. Fish were exposed for 46h to a static (DC) EMF with a permanent bar magnet or to a variable (AC) EMF with an electromagnet. Fish locations were recorded with a digital imaging system, and changes in activity level and distribution relative to the magnet position were quantified at 5-min intervals. Experiments with Fathead Minnow Pimephales promelas, Redear Sunfish Lepomis microlophus, Striped Bass Morone saxatilis, Lake Sturgeon Acipenser fulvescens, and Channel Catfish Ictalurus punctatus produced mixed results. Except for Fathead Minnow, there was no effect on fish activity level. Only Redear Sunfish and Channel Catfish exhibited a change in distribution relative to the position of the magnet, with both species showing an apparent attraction to the EMF source. In a separate experiment, rapid behavioral responses of Paddlefish Polyodon spathula and Lake Sturgeon to the onset of an AC field were recorded with high-speed video. Paddlefish did not react to a variable, 60-Hz magnetic field (i.e., like that emitted by an AC generator or cable), but Lake Sturgeon consistently responded with a variety of altered swimming behaviors. These results will be useful for positioning cables or generators to minimize interactions with EMF-sensitive species. Received August 10, 2012; accepted February 16, 2013

There is considerable interest in the development of marine and hydrokinetic energy projects in rivers, estuaries, and coastal ocean waters of the United States. Hydrokinetic (HK) technologies convert the energy of moving water in river or tidal currents into electricity, without the impacts of dams and impoundments associated with conventional hydropower or the extraction and combustion of fossil fuels. The Federal Energy Regulatory Commission (FERC) maintains a database that displays the geographical distribution of proposed HK projects in inland and tidal waters (FERC 2012). As of March 2012, 77 preliminary permits had been issued to private developers to study HK projects in inland waters, the development of which would total over 8,000 MW. Most of these projects are proposed for the lower Mississippi River. In addition, the issuance of another 27 preliminary permits for HK projects in inland waters, and 3 preliminary permits for HK tidal projects (totaling over 3,100 MW) were under consideration by FERC. Although numerous HK designs are under development (see DOE 2009 for a description of the technologies and their potential environmental effects), the most commonly proposed projects entail arrays of rotating devices, much like submerged wind turbines, that are positioned in the high-velocity (high energy) river channels. The many diverse HK designs imply a diversity of environmental impacts, but a potential impact common to most is the effect on aquatic organisms of electromagnetic fields (EMF) created by the projects. The submerged electrical generator will emit an EMF into the surrounding water, as will underwater cables used to transmit electricity from the generator to the shore, between individual units in an array (inter-turbine cables), and between the array and a submerged step-up transformer. The electric current moving through these cables will induce magnetic fields in the immediate vicinity, which may affect the behavior or viability of fish and benthic invertebrates (Gill et al. 2005, 2009). It is known that numerous marine and freshwater organisms are sensitive to electrical and magnetic fields, often depending on them for such diverse activities as prey location and navigation (DOE 2009; Normandeau et al. 2011). Despite the wide range of aquatic organisms that are sensitive to EMF and the increasing numbers of underwater electrical transmitting cables being installed in rivers and coastal waters, little information is available to assess whether animals will be attracted, repelled, or unaffected by these new sources of EMF. This knowledge gap is especially significant for freshwater systems, where electrosensitive organisms such as paddlefish and sturgeon may interact with electrical transmission cables. We carried out a series of laboratory experiments to test the sensitivity of freshwater fish and invertebrates to the levels of EMF that are expected to be produced by HK projects in rivers. In this context, EM fields are likely to be emitted primarily by generators in the water column and by transmission cables on or buried in the substrate. The HK units will be located in areas of high-velocity waters that are used as only temporary habitats for most riverine species, so long-term exposure of fish and benthic invertebrates to EMF is unlikely. Rather, most aquatic organisms will be briefly exposed to the fields as they drift downstream or migrate upstream. Because the exposure of most aquatic organisms to EMF in a river would be relatively brief and non-lethal, we focused our investigations on detecting behavioral effects. For example, attraction to the EM fields could result in prolonged exposures to the fields or the HK rotor. On the other hand, avoidance reactions might hinder upstream migrations of fish. The experiments reported here are a continuation of studies begun in FY 2010, which focused on the potential effects of static magnetic fields on snails, clams, and fathead minnows (Cada et al. 2011). Those experiments found little indication that the behaviors of these freshwater species were altered by the static magnetic fields that would be created by submerged, direct current (DC)-transmitting electrical cables expected to be used by the HK developers. Laboratory experiments in FY 2011 examined the responses of additional fish species (sunfish, striped bass, and channel catfish) to the static magnetic fields. In addition, the effects of variable magnetic fields (that would be created by the HK generators and AC-transmitting cables) on swimming behavior of two electrosensitive fish species (paddlefish and lake sturgeon) were studied.

One of the most important environmental issues facing the hydropower industry is the adverse impact of hydroelectric projects on downstream fish passage. Fish that migrate long distances as part of their life cycle include not only important diadromous species (such as salmon, shads, and eels) but also strictly freshwater species. The hydropower reservoirs that downstream-moving fish encounter differ greatly from free-flowing rivers. Many of the environmental changes that occur in a reservoir (altered water temperature and transparency, decreased flow velocities, increased predation) can reduce survival. Upon reaching the dam, downstream-migrating fish may suffer increased mortality as they pass through the turbines, spillways and other bypasses, or turbulent tailraces. Downstream from the dam, insufficient environmental flow releases may slow downstream fish passage rates or decrease survival. There is a need to refine our understanding of the relative importance of causative factors that contribute to turbine passage mortality (e.g., strike, pressure changes, turbulence) so that turbine design efforts can focus on mitigating the most damaging components. Further, present knowledge of the effectiveness of turbine improvements is based on studies of only a few species (mainly salmon and American shad). These data may not be representative of turbine passage effects for the hundreds of other fish species that are susceptible to downstream passage at hydroelectric projects. For example, there are over 900 species of fish in the United States. In Brazil there are an estimated 3,000 freshwater fish species, of which 30% are believed to be migratory (Viana et al. 2011). Worldwide, there are some 14,000 freshwater fish species (Magurran 2009), of which significant numbers are susceptible to hydropower impacts. By comparison, in a compilation of fish entrainment and turbine survival studies from over 100 hydroelectric projects in the United States, Winchell et al. (2000) found useful turbine passage survival data for only 30 species. Tests of advanced hydropower turbines have been limited to seven species - Chinook and coho salmon, rainbow trout, alewife, eel, smallmouth bass, and white sturgeon. We are investigating possible approaches for extending experimental results from the few tested fish species to predict turbine passage survival of other, untested species (Cada and Richmond 2011). In this report, we define the causes of injury and mortality to fish tested in laboratory and field studies, based on fish body shape and size, internal and external morphology, and physiology. We have begun to group the large numbers of unstudied species into a small number of categories, e.g., based on phylogenetic relationships or ecological similarities (guilds), so that subsequent studies of a few representative species (potentially including species-specific Biological Index Testing) would yield useful information about the overall fish community. This initial effort focused on modifying approaches that are used in the environmental toxicology field to estimate the toxicity of substances to untested species. Such techniques as the development of species sensitivity distributions (SSDs) and Interspecies Correlation Estimation (ICE) models rely on a considerable amount of data to establish the species-toxicity relationships that can be extended to other organisms. There are far fewer studies of turbine passage stresses from which to derive the turbine passage equivalent of LC{sub 50} values. Whereas the SSD and ICE approaches are useful analogues to predicting turbine passage injury and mortality, too few data are available to support their application without some form of modification or simplification. In this report we explore the potential application of a newer, related technique, the Traits-Based Assessment (TBA), to the prediction of downstream passage mortality at hydropower projects.

There is considerable interest in the development of marine and hydrokinetic energy projects in rivers, estuaries, and coastal ocean waters of the United States. Hydrokinetic (HK) technologies convert the energy of moving water in river or tidal currents into electricity, without the impacts of dams and impoundments associated with conventional hydropower or the extraction and combustion of fossil fuels. The Federal Energy Regulatory Commission (FERC) maintains a database that displays the geographical distribution of proposed HK projects in inland and tidal waters (FERC 2012). As of March 2012, 77 preliminary permits had been issued to private developers to study HK projects in inland waters, the development of which would total over 8,000 MW. Most of these projects are proposed for the lower Mississippi River. In addition, the issuance of another 27 preliminary permits for HK projects in inland waters, and 3 preliminary permits for HK tidal projects (totaling over 3,100 MW) were under consideration by FERC. Although numerous HK designs are under development (see DOE 2009 for a description of the technologies and their potential environmental effects), the most commonly proposed current-based projects entail arrays of rotating devices, much like submerged wind turbines, that are positioned in the high-velocity (highmore » energy) river channels. The many diverse HK designs imply a diversity of environmental impacts, but a potential impact common to most is the risk for blade strike to aquatic organisms. In conventional hydropower generation, research on fish passage through reaction turbines at low-head dams suggested that strike and mortality for small fish could be low. As a consequence of the large surface area to mass ratio of small fish, the drag forces in the boundary layer flow at the surface of a rotor blade may pull small fish around the leading edge of a rotor blade without making physical contact (Turnpenny 1998, Turnpenny et al. 2000). Although there is concern that small, fragile fish early life stages may be unable to avoid being struck by the blades of hydrokinetic turbines, we found no empirical data in the published literature that document survival of earliest life-stage fish in passage by rotor blades. In addition to blade strike, research on passage of fish through conventional hydropower turbines suggested that fish mortalities from passage through the rotor swept area could also occur due to shear stresses and pressure chances in the water column (Cada et al. 1997, Turnpenny 1998). However, for most of the proposed HK turbine designs the rotors are projected to operate a lower RPM (revolutions per minute) than observed from conventional reaction turbines; the associated shear stress and pressure changes are expected to be lower and pose a smaller threat to fish survival (DOE 2009). Only a limited number of studies have been conducted to examine the risk of blade strike from hydrokinetic technologies to fish (Turnpenny et al. 1992, Normandeau et al. 2009, Seitz et al. 2011, EPRI 2011); the survival of drifting or weakly swimming fish (especially early life stages) that encounter rotor blades from hydrokinetic (HK) devices is currently unknown. Our study addressed this knowledge gap by testing how fish larvae and juveniles encountered different blade profiles of hydrokinetic devices and how such encounters influenced survivorship. We carried out a laboratory study designed to improve our understanding of how fish larvae and juvenile fish may be affected by encounters with rotor blades from HK turbines in the water column of river and ocean currents. (For convenience, these early life stages will be referred to as young of the year, YOY). The experiments developed information needed to quantify the risk (both probability and consequences) of rotor-blade strike to YOY fish. In particular, this study attempted to determine whether YOY drifting in a high-velocity flow directly in the path of the blade leading edge will make contact with the rotor blade or will bypass the blade while entrained in the boundary layer of water flowing over the blade surface. The study quantified both immediate and delayed mortalities (observed immediately, 3 hours, and 24 hours after encountering the blade) among freshwater YOY fish resulting from contact with the blade or turbulent flows in the wake of the blade.« less

Indicators of the environmental sustainability of biofuel production, distribution, and use should be selected, measured, and interpreted with respect to the context in which they are used. The context of a sustainability assessment includes the purpose, the particular biofuel production and distribution system, policy conditions, stakeholder values, location, temporal influences, spatial scale, baselines, and reference scenarios. We recommend that biofuel sustainability questions be formulated with respect to the context, that appropriate indicators of environmental sustainability be developed or selected from more generic suites, and that decision makers consider context in ascribing meaning to indicators. In addition, considerations such as technical objectives, varying values and perspectives of stakeholder groups, indicator cost, and availability and reliability of data need to be understood and considered. Sustainability indicators for biofuels are most useful if adequate historical data are available, information can be collected at appropriate spatial and temporal scales, organizations are committed to use indicator information in the decision-making process, and indicators can effectively guide behavior toward more sustainable practices.

The patterns of biodiversity in freshwater systems are shaped by biogeography, environmental gradients, and human-induced factors. In this study, we developed empirical models to explain fish species richness in subbasins of the Arkansas-White-Red River basin as a function of discharge, elevation, climate, land cover, water quality, dams, and longitudinal position. We used information-theoretic criteria to compare generalized linear mixed models and identified well-supported models. Subbasin attributes that were retained as predictors included discharge, elevation, number of downstream dams, percent forest, percent shrubland, nitrate, total phosphorus, and sediment. The random component of our models, which assumed a negative binomial distribution, included spatial correlation within larger river basins and overdispersed residual variance. This study differs from previous biodiversity modeling efforts in several ways. First, obtaining likelihoods for negative binomial mixed models, and thereby avoiding reliance on quasi-likelihoods, has only recently become practical. We found the ranking of models based on these likelihood estimates to be more believable than that produced using quasi-likelihoods. Second, because we had access to a regional-scale watershed model for this river basin, we were able to include model-estimated water quality attributes as predictors. Thus, the resulting models have potential value as tools with which to evaluate the benefits of water quality improvements to fish.

Indicators are needed to assess environmental sustainability of bioenergy systems. Effective indicators will help in the quantification of benefits and costs of bioenergy options and resource uses. We identify 19 measurable indicators for soil quality, water quality and quantity, greenhouse gases, biodiversity, air quality, and productivity, building on existing knowledge and on national and international programs that are seeking ways to assess sustainable bioenergy. Together, this suite of indicators is hypothesized to reflect major environmental effects of diverse feedstocks, management practices, and post-production processes. The importance of each indicator is identified. Future research relating to this indicator suite is discussed, including field testing, target establishment, and application to particular bioenergy systems. Coupled with such efforts, we envision that this indicator suite can serve as a basis for the practical evaluation of environmental sustainability in a variety of bioenergy systems.

Adding bioenergy to the U.S. energy portfolio requires long-term profitability for bioenergy producers and long-term protection of affected ecosystems. In this study, we present steps along the path toward evaluating both sides of the sustainability equation (production and environmental) for switch grass (Panicum virgatum) using the Soil and Water Assessment Tool (SWAT). We modeled production of switch grass and river flow using SWAT for current landscapes at a regional scale.. To quantify feedstock production, we compared lowland switchgrass yields simulated by SWAT with estimates from a model based on empirical data for the eastern U.S. The two produced similar geographic patterns. Average yields reported in field trials tended to be higher than average SWAT-predicted yields, which may nevertheless be more representative of production-scale yields. As a preliminary step toward quantifying bioenergy-related changes in water quality, we evaluated flow predictions by the SWAT model for the Arkansas-White-Red river basin. We compared monthly SWAT flow predictions to USGS measurements from 86 subbasins across the region. Although agreement was good, we conducted an analysis of residuals (functional validation) seeking patterns to guide future model improvements. The analysis indicated that differences between SWAT flow predictions and field data increased in downstream subbasins and in subbasins with higher percentage of water Together, these analyses have moved us closer to our ultimate goal of identifying areas with high economic and environmental potential for sustainable feedstock production.

Hydrokinetic energy technologies have been proposed as renewable, environmentally preferable alternatives to fossil fuels for generation of electricity. Hydrokinetic technologies harness the energy of water in motion, either from waves, tides or from river currents. For energy capture from free-flowing rivers, arrays of rotating devices are most commonly proposed. The placement of hydrokinetic devices in large rivers is expected to increase the underwater structural complexity of river landscapes. Moore and Gregory (1988) found that structural complexity increased local fish populations because fish and other aquatic biota are attracted to structural complexity that provides microhabitats with steep flow velocity gradients (Liao 2007). However, hydrokinetic devices have mechanical parts, blades, wings or bars that move through the water column, posing a potential strike or collision risk to fish and other aquatic biota. Furthermore, in a setting with arrays of hydrokinetic turbines the cumulative effects of multiple encounters may increase the risk of strike. Submerged structures associated with a hydrokinetic (HK) project present a collision risk to aquatic organisms and diving birds (Cada et al. 2007). Collision is physical contact between a device or its pressure field and an organism that may result in an injury to that organism (Wilson et al. 2007). Collisions can occur between animals and fixed submerged structures, mooring equipment, horizontal or vertical axis turbine rotors, and structures that, by their individual design or in combination, may form traps. This report defines strike as a special case of collision where a moving part, such as a rotor blade of a HK turbine intercepts the path of an organism of interest, resulting in physical contact with the organism. The severity of a strike incidence may range from minor physical contact with no adverse effects to the organism to severe strike resulting in injury or death of the organism. Harmful effects to animal populations could occur directly (e.g., from strike mortality of individuals) or indirectly (e.g., if the loss of prey species to strike reduces food for predators). Although actively swimming or passively drifting animals may collide with any of the physical structures associated with hydrokinetic devices, turbine rotors are the most likely sources for risk of strike or significant collision (DOE 2009). It is also possible that during a close encounter with a HK device no physical contact will be made between the device and the organism, either because the animal avoids the device by successfully changing its direction of movement, or by successfully evading any moving parts of the device. Oak Ridge National Laboratory (ORNL) has been funded by the US Department of Energy (DOE) Waterpower Program to evaluate strike potential and consequences for Marine and Hydrokinetic (MHK) technologies in rivers and estuaries of the United States. We will use both predictive models and laboratory/field experiments to evaluate the likelihood and consequences of strike at HK projects in rivers. Efforts undertaken at ORNL address three objectives: (1) Assess strike risk for marine and freshwater organisms; (2) Develop experimental procedures to assess the risk and consequences of strike; and (3) Conduct strike studies in experimental flumes and field installations of hydrokinetic devices. During the first year of the study ORNL collected information from the Federal Energy Regulatory Commission (FERC) MHK database about geographical distribution of proposed hydrokinetic projects (what rivers or other types of systems), HK turbine design (horizontal axis, vertical axis, other), description of proposed axial turbine (number of blades, size of blades, rotation rate, mitigation measures), and number of units per project. Where site specific information was available, we compared the location of proposed projects rotors within the channel (e.g., along cutting edge bank, middle of thalweg, near bottom or in midwater) to the general locations of fish in the river (shoreline, bottom/midwater/surface of channel) to ascertain potential interactions. In addition, we are collaborating and communicating with scientists at other national laboratories and industry who are also developing information useful to this task. For example, other studies being funded by DOE include evaluations of different in-current (hydrokinetic) turbine designs for their effects on rates and severity of blade strike and likelihood of cavitation. This report summarizes activities completed during the first year of a three-year study.

As the US begins to integrate biomass crops and residues into its mix of energy feedstocks, tools are needed to measure the long-term sustainability of these feedstocks. Two aspects of sustainability are long-term potential for profitably producing energy and protection of ecosystems influenced by energy-related activities. The Soil and Water Assessment Tool (SWAT) is an important model used in the efforts to quantify both aspects. To quantify potential feedstock production, they used SWAT to estimate switchgrass yields at a national scale. The results from this analysis produced a map of the potential switchgrass yield along its natural eastern range. To quantify ecological protection, they are using the SWAT model to forecast changes in water quality and fish richness as a result of landscape alterations due to incorporating bioenergy crops. They have implemented the SWAT model in the Arkansas-Red-White region, which drains into the Mississippi River, and they present their methods here. They identified two sub-watersheds for sensitivity analysis and calibration of the water quality results, and then, explored ways to apply the calibration results to the whole region and validate the model setup. They also present an overview of their research in which results from the calibrated regional SWAT modelmore » were used to analyze potential changes in fish biodiversity. Only by evaluating the energy and environmental implications of landscape changes can we make informed decisions about bioenergy at the national scale, and the SWAT model will enable us to reach that goal.« less

Freshwater fish assemblages are sensitive to changes in land use, but it is unclear how rapidly assemblages respond to such change or how closely they track physical changes in the stream environment. We monitored fish assemblages at the outflow of three watersheds on the outer coastal plain of Mississippi over a period of 8 y. The watersheds differed in patterns of land use, being predominantly forested, rapidly urbanizing, and long-urbanized, respectively. Watersheds were distinct in fish species composition, differing primarily in abundance of Etheostoma lynceum, E. stigmaeum, Luxilus chrysocelphalus and Lythrurus roseipinnis. Species richness was consistently greatest at the predominantly forested site and least at the urbanized site. Fish assemblages were distinguish able in terms of substrate preference, water-speed, silt tolerance, and trophic habit. The stream draining the urbanizing watershed showed an increase in richness of species of high silt tolerance and a decrease in richness of those preferring a gravel substrate over the sampling period. Contrail, to expectation, annual variation in composition was modest relative to differences among sites. Annual variation in richness and numbers was unrelated to measures of streamflow or seasonal precipitation. Changes in stream character related to land use change appear to have impacted the fish assemblages of these streams, but the transition to air urban fish assemblage in the urbanizing stream occurred before the study period, well before the obvious signs of physical degradation appeared at the site.