A jointly prepared, interagency (US Environmental Protection Agency [USEPA] and the US Nuclear Regulatory Commission [USNRC]), §316(a) Technical Guidance Manual has been the primary guide to ecological studies of thermal discharges at power plants since 1977. It reflected contemporary ecological theory, which assumed that undisturbed populations and ecosystems possessed a balanced and relatively unchanging structure and function that could be disrupted by addition of heat from a thermal discharge. It was intended primarily to facilitate the licensing of proposed nuclear power plants and thus focused on predictive assessments. Since 1977, however, scientific and regulatory contexts of §316(a) assessments have changed. Ecologists abandoned the notion of "balance" in populations and ecosystems and now recognize that natural systems are always changing spatially and temporally. Regulatory emphasis has shifted from predictive assessments at new plants, largely based on thermal-tolerance laboratory data, to retrospective assessments based on field data at operating plants. We suggest updates to thermal-assessment studies based on modern ecological theory and recent thermal-assessment practice. The concepts we outline are fully consistent with statutory language and may assist in design and implementation of study plans by applicants and their consultants, development of discharge permits by USEPA or state agencies, and reviews of assessment documents by interested public and environmental organizations. Integr Environ Assess Manag 2022;18:459-468. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

In the Fall of 2016 a workshop was held which brought together over 50 scientists from the ecological and radiological fields to discuss feasibility and challenges of reintegrating ecosystem science into radioecology. There is a growing desire to incorporate attributes of ecosystem science into radiological risk assessment and radioecological research more generally, fueled by recent advances in quantification of emergent ecosystem attributes and the desire to accurately reflect impacts of radiological stressors upon ecosystem function. This paper is a synthesis of the discussions and consensus of the workshop participant's responses to three primary questions, which were: 1) How can ecosystem science support radiological risk assessment? 2) What ecosystem level endpoints potentially could be used for radiological risk assessment? and 3) What inference strategies and associated methods would be most appropriate to assess the effects of radionuclides on ecosystem structure and function? The consensus of the participants was that ecosystem science can and should support radiological risk assessment through the incorporation of quantitative metrics that reflect ecosystem functions which are sensitive to radiological contaminants. The participants also agreed that many such endpoints exit or are thought to exit and while many are used in ecological risk assessment currently, additional data need to be collected that link the causal mechanisms of radiological exposure to these endpoints. Finally, the participants agreed that radiological risk assessments must be designed and informed by rigorous statistical frameworks capable of revealing the causal inference tying radiological exposure to the endpoints selected for measurement.

In Canada, the Fisheries Act requires all water takers to avoid, mitigate and offset fish losses. To satisfy the act’s requirements, operators of power plants are required to undertake habitat restoration projects to compensate for fish impinged and entrained at cooling water intake structures. Scaling the quantity of restoration needed, and measuring whether adequate compensation has been achieved, requires a metric that expresses the losses and gains in comparable units. Development of such a metric is especially difficult in the case of power plants, because the losses often consist of a mix of species and life stages that are very different from those produced by technically feasible restoration projects. This paper documents the method that has been developed for quantifying offsets for impingement and entrainment at the Bruce Generating Stations on the eastern shore of Lake Huron, and demonstrates how the method is being used to estimate the offset to be provided by removal of a dam on the nearby Saugeen River.

As Senior Editors of a global publication devoted to bridging the gap between science and environmental policy at the Society of Environmental Toxicology and Chemistry (SETAC), we encourage academia, business, and government to be visionary and to adopt a forward-looking approach to tackling the environmental challenges that face our global community of nations in the 21st century. Major shifts of leadership are currently occurring globally. The election of a new US President is one of many recent political developments in the European Union, Africa, South America, and Asia, that are likely to have a profound influence on regional and global environmental policy during the next decade. New leadership reminds us of the importance of investments in science education and environmental protection. Collaboration among the academic, business, and government communities is essential to foster the capacity to manage natural resources effectively and sustainably, and to address the threats posed by environmental pressures and resource scarcities that increasingly affect global prosperity. Environmental problems know no borders, and addressing the most pressing challenges demands worldwide collaboration. Reflecting on 13 years of publishing environmental science research and policy analysis in Integrated Environmental Assessment and Management (IEAM), we see an opportunity for political leaders to forge a common vision for the future and to build an agenda that recognizes the interdependence of economic vitality, environmental quality, and social equity. The Editorial Board at IEAM has concentrated on several global environmental challenges since its inception. Together with our authors from the global academic, business, and regulatory communities, we are committed to deepening the understanding of the environmental impacts from multiple stressors caused by human activity and that affect an ever-evolving natural environment. For example, we seek to publish innovative approaches for improving chemicals management and managing the life cycle of materials and consumer products that are distributed around the world. We also seek to improve knowledge and best practices that incorporate the concepts of ecosystem services into environmental assessment and planning. In doing so we also strive to strengthen scientific capabilities in developing countries. Recently, SETAC's Global Horizon Scanning Project called on scientists and engineers from around the world to identify our most pressing environmental quality research needs. Climate change, food safety, sustainable and safe water supplies, and ecological integrity are critically important to global security. Unfortunately, sustained efforts to understand and manage the subtle yet powerful consequences of environmental degradation tend to be deferred during hard times and overlooked in good times. When they are not deferred or overlooked, they are too often politicized to serve short-term interests. This is a global, systemic problem that cannot be solved without broad engagement of political leaders from around the globe. The Senior Editorial Board at IEAM is committed to heralding the information and ideas of talented environmental scientists and engineers that could be harnessed by political leaders to promote global security through sustainable ecological productivity. The time is right for our public- and private-sector leaders to use integrated environmental assessment and management as an engine to drive us towards a new era of global security through enlightened ecosystem management. Senior Editorial Board Integrated Environmental Assessment and Management Sabine Apitz Roberta Attanasio Thomas Backhaus Lawrence Barnthouse Graeme Batley Kate Brauman Bryan Brooks Peter Chapman Michael Griffin Lawrence Kapustka Wayne Landis Kenneth Leung Igor Linkov James Meador Stig Olsen Lawrence Tannenbaum John Toll Glenn Suter Richard Wenning

In a 2002 paper, we discussed the technical challenges associated with quantifying natural resource injuries, service losses and damages, and suggested some actions that might help to overcome them. An important suggestion was to consider using some of the approaches in ecological risk assessment to help evaluate potential natural resource injuries, and ultimately in some cases to help translate those injuries into natural resource service loss. This was based on the observation that ecological risk assessment and natural resource damage assessments use much of the same types of data, but at that time the experience base with ecological risk assessment was greater than for natural resource damage assessments. We also discussed some of the issues in applying the then current Department of Interior natural resource damage assessments regulations. Since our 2002 publication the scientific literature, relevant regulations, the global context and more have changed. In the current paper we focus on the technical and regulatory changes in natural resource damage assessments practice since 2002, and use recent reports and publications to illustrate those changes and identify new directions in natural resource damage assessments.

Monetizing ecological benefits of reducing impingement and entrainment (I&E) at cooling water intake structures presents both ecological and economic challenges. Ecological challenges arise because it is difficult to demonstrate and measure these impacts. Economic challenges arise because of these ecological uncertainties and because many of the potentially affected ecosystem services cannot be valued using traditional methods. Under a recently promulgated U.S. regulation certain power generation and industrial water permit applicants may be required to monetize these "nonuse" benefits. However, stated preference (SP) surveys, the only method available for valuing nonuse services have not seen acceptance by mainstream economists. This paper describes an approach to valuation that incorporates the ecological service function approach advocated by the USEPA Science Advisory Board to characterize impacts. Data and models are used to quantify, to the extent possible, direct and indirect impacts of I&E on ecosystem services. Nonuse values are then estimated by an SP survey that measures respondents' willingness to pay for reducing I&E. Methods are proposed for calibrating and validating results including identifying the source of nonuse values from commonly ascribed motivations (i.e. existence, bequest, altruistic), considering the role of pre-survey awareness of impacts, and evaluating results in the context of respondent willingness to pay for other nonuse benefits. (C) 2016 Published by Elsevier Ltd.

This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters' accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks. Scientific research conducted in a variety of laboratory and field settings has improved our knowledge of the effects of ionizing radiation on the environment. However, the results from such studies sometimes appear contradictory and there is disagreement about the implications for risk assessment. The Symposium discussions therefore focused on issues that might lead to different interpretations of the results, such as laboratory versus field approaches, organism versus population and ecosystemic inference strategies, dose estimation approaches and their significance under chronic exposure conditions. The participating scientists, from across the spectrum of disciplines and research areas, extending also beyond the traditional radioecology community, successfully developed a constructive spirit directed at understanding discrepancies. From the discussions, the group has derived seven consensus statements related to environmental protection against radiation, which are supplemented with some recommendations. Each of these statements is contextualized and discussed in view of contributing to the orientation and integration of future research, the results of which should yield better consensus on the ecological impact of radiation and consolidate suitable approaches for efficient radiological protection of the environment.

Radiation protection goals for ecological resources are focussed on ecological structures and functions at population-, community-, and ecosystem-levels. The current approach to radiation safety for non-human biota relies on organism-level endpoints, and as such is not aligned with the stated overarching protection goals of international agencies. Exposure to stressors can trigger non-linear changes in ecosystem structure and function that cannot be predicted from effects on individual organisms. From the ecological sciences, we know that important interactive dynamics related to such emergent properties determine the flows of goods and services in ecological systems that human societies rely upon. A previous Task Group of the IUR (International Union of Radioecology) has presented the rationale for adding an Ecosystem Approach to the suite of tools available to manage radiation safety. In this paper, we summarize the arguments for an Ecosystem Approach and identify next steps and challenges ahead pertaining to developing and implementing a practical Ecosystem Approach to complement organism-level endpoints currently used in radiation safety.

•Losses of fish at cooling water intake structures are controversial.•Impacts of these losses have been investigated for 40 years.•Most published studies show that fish populations have not been affected.•Available science does not support need for aggressive regulation.

The recent accident at the Fukushima I nuclear power plant in Japan (also known as Fukushima Daiichi) captured the world's attention and re-invigorated concerns about the safety of nuclear power technology. The Editors of Integrated Environmental Assessment and Management invited experts in the field to describe the primary issues associated with the control and release of radioactive materials to the environment, particularly those that are of importance to the health of the human populations and the ecological systems that populate our planet. This collection of invited short commentaries aims to inform on the safety of nuclear power plants damaged by natural disasters and provide a primer on the potential environmental impacts. The intent of these invited commentaries is not to fuel the excitement and fears about the Fukushima Daiichi incident; rather, it is to collect views and comments from some of the world's experts on the broad science and policy challenges raised by this event, and to provide high-level views on the science issues that surround this situation in order to improve our collective ability to avoid or at least minimize the consequences of future events.

Interest and concern about the human health and environmental impacts of chemicals in personal care products and other consumer products that are released to the environment through wastewater treatment systems are a continuing issue. Examples include detergents and other cleaning agents, solvents, household pesticides, fragrances, pharmaceuticals, biocides, and antimicrobials such as triclosan, the subject of a set of 3 articles that appear in this issue of Integrated Environmental Assessment and Management (Bock et al. 2010; Fuchsman et al. 2010; Lyndall et al. 2010). Large quantities of environmental data have been generated and published by scientists from industrial, regulatory, and academic organizations with widely different perspectives concerning the fate and effects of these products and their ingredients. The “big picture” integrating sources, fate, and effects of these materials on human health and ecosystems can be clouded by the sheer volume of the observations, many of which may be in apparent or real conflict. Careful and comprehensive critical reviews that seek to integrate the available information into a coherent whole can be invaluable by providing manufacturers, consumers, and regulatory agencies with objective syntheses of the scientific facts. Chemical identity and relevant physicochemical properties that determine environmental partitioning and potential for food web transfer and biomagnification Chemical reactivity or degradability in relevant media ranging from the atmosphere to biosolids to organisms “Mode of entry” into the environment, in this case in water effluents destined mainly for wastewater treatment (WWT) Fate of the chemical within a treatment plant, including degradation and partitioning between biosolids and treated wastewater Quantities used and how these vary both regionally and nationally Key characteristics of receiving environments, and how these vary regionally and nationally From this information, it is usually possible to identify the key environmental pathways of the chemical, hence the processes that control levels in potentially affected environments, and the variability of those levels as functions of key environmental and demographic characteristics. Mass balance models that simulate the fate and transport of the substance are important components of any such assessments. Triclosan is contained in numerous consumer products and has been found worldwide in municipal and industrial wastewater (Reiss et al. 2002). The percentage of wastewater containing triclosan that is treated, as well as the treatment methods, varies greatly. In a typical wastewater treatment plant in North America, the key pathways for triclosan are sorption to biosolids, biodegradation during secondary treatment, and flowthrough to the water effluent discharged from the plant. Triclosan sorbed to biosolids that are subsequently applied to land may potentially affect terrestrial biota. Triclosan contained in aqueous effluent may potentially affect aquatic biota. At least in principle, bioaccumulation in food chains may be possible. The wastewater treatment study conducted by Bock et al. (2010) illustrates nicely the use of a relatively simple steady-state WWT fugacity model to support and enhance monitoring data collected either locally or regionally in the vicinity of WWT plants. More complex dynamic models can be applied and indeed should be applied when discharges are more episodic in nature. Discharges of triclosan most likely result from repeated or continuous use; thus, it is doubtful the use of more sophisticated dynamic fate models would add significant insights. The simple model also has the advantage of facilitating more rapid and transparent sensitivity and probabilistic analyses as undertaken by Bock et al. (2010). It is always satisfying when a model yields results that are consistent with observations, because this suggests that the dominant fate processes are well identified and described quantitatively. On the other hand, significant discrepancies between model predictions and observations indicate that the underlying processes are inadequately understood. The results reported by Bock et al. (2010) are consistent with observations reported in WWT effluent outside the United States; however, triclosan concentrations in US effluent are significantly overestimated by their model. Although as applied to US WWT effluents the model is conservative and overstates potential risks, the failure to adequately represent US effluent data suggests that one or more key processes in WWT plants are not adequately understood. Further work to understand this discrepancy is needed and may prove to be of practical significance. Another appealing aspect of the Bock et al. (2010) modeling work is that their results are presented not as single values, but as a distribution of results presented as cumulative distribution curves. These curves show both the performance of the modeled processes and the likely range of triclosan concentrations that, in this case, extend over 2 orders of magnitude and depend heavily on the volumes of personal care and consumer products containing triclosan used by consumers who are connected to the WWT plant. Although the treatment efficiency of WWT plant effluents is high, this is in part attributable to the significant partitioning into sludges. Therefore, the fate of residual levels of triclosan in land-applied biosolids (sludges) must be considered (Fuchsman et al. 2010). The terrestrial ecological risk assessment reported by Fuchsman et al. (2010) addresses ecological risks to soil microorganisms and invertebrates, plants, mammals, and birds. A relatively simple fugacity model is used to estimate biotic concentrations. Regrettably, there is a lack of corresponding monitoring data to validate the risk model results. Hence, the model presented by Fuchsman et al. (2010) serves 2 purposes: first, it yields estimates of concentrations and approximates effect levels, although such estimates must be treated with caution; and second, it identifies species that are likely at risk and should be the focus for further empirical studies of triclosan degradation in biosolid-amended soils. Appropriately, the model is conservative in that it addresses initial post-application steady-state equilibrium partitioning, thus ignoring the effect of triclosan degradation. The BASL 4 model can provide information on the time decay of concentrations, but this feature was not applied by Fuchsman et al. (2010). Fuchsman et al. (2010) also used a probabilistic approach to capture the range of possible exposure and effect levels and identify sensitive model parameters. Most WWT jurisdictions, particularly in North America, regulate biosolid application rates and frequencies to avoid “sawtooth” year-to-year buildup of contamination and adverse effects on nitrogen runoff and nutrient status (EPA 1999; Peterson et al. 2003). These rates vary widely between jurisdictions, and allowable numerical limits are likely based more on professional judgment than on quantitative science. A compelling case can be made that there is a need for more empirical studies, model development, and validation, taking into account the complicating issues of tillage practices, organic carbon partitioning and decay, bioavailability as a function of time, plant uptake, and food chain biomagnification and biotransformation. The study carried out by Fuchsman et al. (2010) is a useful start in this direction. Undoubtedly, triclosan is only one of many substances for which this pathway is significant; brominated flame retardants are another obvious example. A striking observation from comparison of the work by Fuchsman et al. (2010) to Lyndall et al. (2010), perhaps not surprisingly, given the general state of ecological risk assessment practice is that terrestrial risk assessment is a grossly underdeveloped discipline in comparison with aquatic risk assessment in terms of scientific support and research effort. The Lyndall et al. (2010) aquatic risk assessment for triclosan in WWT effluent discharges to surface waters builds on an earlier assessment by Capdevielle et al. (2008). The study expands further on the previous work and provides a more comprehensive evaluation of the fate of triclosan in water, sediment, and aquatic biota. The 4 models used by Lyndall et al. (2010) (i.e., a simple receiving water dilution model, a multimedia fugacity model, the AQUAWEB bioaccumulation/food web model, and a USEPA dietary exposure model) benefit from the probabilistic approach used in the Bock et al. (2010) and Fuchsman et al. (2010) studies. The exposure-effects distributions and confidence limits reported by Lyndall et al. (2010) provide an excellent depiction of the proximity of expected tissue residue levels in different aquatic species to adverse effects. Likewise, the mammalian and avian exposures predicted by the models and expressed as doses and clearly compared with available toxicity benchmarks reported in the literature provide a foundation on which to focus further study. A complication in the case of triclosan is its potential ionization (the pKa value ranges between 7.9 and 8.14). Dissociation can have a profound effect on partitioning, bioavailability, degradation, and toxicity, and the ultimate effect on risk may not be immediately obvious. In addition to triclosan, methyl triclosan is frequently detected. Formation is probably by methylation of triclosan, and the product is expected to exhibit greater hydrophobicity and bioaccumulation. This finding raises the issue of the need to include related chemical species such as degradation products if a truly complete environmental fate evaluation of triclosan is needed to support future regulatory decision making. The issue of ionization undoubtedly applies to many other substances, including a large number of pharmaceutical compounds, and deserves further attention. Reflecting on the state of the science and the integration of the impressive quantity of literature reviewed and integrated into a triclosan risk assessment, the work by Bock et al. (2010), Fuchsman et al. (2010), and Lyndall et al. (2010) provides an invaluable source of reference material and helps immensely to guide future research by scientists in this field. Collectively, their work also serves as an example to guide future assessments of other chemical substances, something much needed in light of the new directions in chemical management and regulation unfolding in Canada, the European Union, the United States, and other countries. A strength of their approach is the comprehensive treatment of relevant pathways, media, processes, and ecological receptors. The framework illustrated by their work on triclosan clearly demonstrates the benefits of adopting a “monitoring plus modeling” approach, each adding credibility to the other. The work demonstrates that for broad or screening-level assessments, the use of fugacity models is particularly appropriate because of their simplicity and transparency and the ease with which they can be incorporated into probabilistic evaluations. The equilibrium assumptions inherent in several aspects of these models are clearly apparent. For example, the bioaccumulation and food webs used by Fuchsman et al. (2010) and Lyndall et al. (2010) provide a starting point for more detailed and accurate modeling simulations and identify specific monitoring data requirements. Further, the work clearly identifies subject areas for further research and assessment. The ultimate book on triclosan has not yet been written. The present work is certainly not the “last word” or “final chapter,” but it represents a very significant and exemplary chapter toward that goal. The study could easily be extended to assess the fate and effects of triclosan in additional environmental settings, such as high-density urban centers, developing nations, and arctic, tropical, or arid environments. The models used could be easily modified to accommodate new data relating to the chemistry and environmental toxicology of triclosan. Because of its simplicity and generality, the risk assessment and modeling framework demonstrated by the work on triclosan could be applied to a wide variety of consumer products and pharmaceuticals for which the primary route of entry to the environment involves releases from WWT plants. We encourage scientists and regulatory agencies interested in these types of products to evaluate the potential applicability of this approach to other chemicals of interest. The authors of this commentary served on an independent science panel convened in 2009 to review the work conducted by Bock et al. (2010), Fuchsman et al. (2010), and Lyndall et al. (2010). They were compensated for the review and for preparation of this commentary by the Colgate-Palmolive Company. The views expressed herein are solely those of the authors.

Abstract Risk assessments and risk management decisions concerning risks to wild fish populations resulting from exposures to polychlorinated biphenyls (PCBs) and related chemicals have been based primarily on observations of effects of chemicals on individual organisms. Although the development and application of population-level ecological risk-assessment methods is proceeding at a rapid pace, the organism-level approach is still being justified by arguments that population-level ecological risk assessment is in an early stage of development and has not been shown to be reliable. This article highlights the importance of including population-level effects in risk-management decision-making, by examining the effects of exposures to PCBs on fish populations inhabiting the Hudson River, New York, USA, a system in which data have been collected for approximately 30 y concerning both concentrations of PCBs in sediment and fish tissue and the abundance and reproduction of exposed fish populations. We previously tested hypotheses concerning the effects of PCBs on the striped bass population of the Hudson River, and found that the available data conflicted with all of these hypotheses. Here, we report results of similar analyses of effects of historic PCB exposures on the Hudson River white perch population, using an extended data set that recently became available. As with striped bass, we found no correlation between maternal PCB tissue concentrations and any measure of reproductive success in Hudson River white perch during the 30-y period covered by the data set. Together with results of studies performed on fish populations exposed to PCBs at other sites, our results clearly demonstrate that physiological and genetic adaptation, biological compensation, and other ecological processes influence responses of fish populations to PCB exposures and should be considered in risk management decision-making.

Twenty-five years ago, ecological assessments were being performed by different organizations, using different principles and methods, with little or no communication between different groups and no means for reconciling conflicts and inconsistencies between assessment methodologies. The recognition by practitioners of environmental assessment of the need for a unifying conceptual framework stimulated the development of today's Framework and Guidelines for Ecological Risk Assessment (ERA). This paper discusses the success of ERA as a process for linking environmental science to decision making, using 3 recently published case studies involving establishment of baseline ecological risks at a contaminated site, probabilistic assessment of regional risks of pesticide use, and regulation of pharmaceutical product manufacture. Some promising future directions in ERA are briefly discussed, and 3 critical challenges to future success are identified.

Integrated Environmental Assessment and ManagementVolume 4, Issue 1 p. 4-4 Letter to the Editor On the use of mathematical models in ecological risk assessments: A response to tannenbaum Lawrence W Barnthouse, Lawrence W Barnthouse barnthouse@lwb-env.com LWB Environmental Services, Inc., 1620 New London Rd., Hamilton, Ohio 45013, USASearch for more papers by this author Lawrence W Barnthouse, Lawrence W Barnthouse barnthouse@lwb-env.com LWB Environmental Services, Inc., 1620 New London Rd., Hamilton, Ohio 45013, USASearch for more papers by this author First published: 05 November 2009 https://doi.org/10.1002/ieam.5630040103Citations: 3Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume4, Issue1January 2008Pages 4-4 RelatedInformation

A method was developed for assessing coastwide effects of power plant impingement and entrainment on managed fish stocks. The method imbeds an assessment of anthropogenic effects that occur during the first year of life of fish (the period when most entrainment and impingement occur) into a standard age-structured stock assessment that addresses age-l and older fish. The method thereby provides a straightforward means for comparing the effects of entrainment and impingement mortality to other forms of anthropogenic mortality affecting coastwide fish stocks. The method uses standard equations from fishery science that represent the relationships among independent competing forces of mortality, stock abundance, and landings. Power plant mortality is treated like fishing mortality, and power plant losses are treated like fishery landings. The total age-0 natural mortality rate is allocated to the individual age-0 life stages based on a power function relating daily natural mortality rates to age-specific dry weights of fish. An illustrative example of the use of the method is presented for the Atlantic coast stock of Atlantic menhaden Brevoortia tyrannus, which was chosen because it is a coastwide stock, has a coastwide fishery, and is described by high-quality fisheries-dependent data. However, because available entrainment and impingement data were not adequate to support defensible coastwide estimates of the annual numbers killed by entrainment and impingement, actual estimates of the effects of entrainment and impingement on the coastwide Atlantic menhaden stock could not be computed. The method could be used to address the effects of any form of anthropogenic mortality affecting age-0 fish, including loss of habitat, effects of toxic substances, fishing mortality, and fishery bycatch, provided that valid coastwide estimates of the annual numbers of fish killed by the source of mortality are available.

Introduction, L.W. Barnthouse, W.R. Munns, Jr., and M.T. Sorensen THE MANAGEMENT-SCIENCE INTERFACE Managing Risk to Ecologic Populations, G.R. Biddinger, P. Calow, P. Delorme, G. Harris, B. Hope, B.L. Lin, M. Sorensen, and P. van den Brink Population Protection Goals, C. Menzie, N. Bettinger, A. Fritz, L. Kapustka, H. Regan, V. Moller, and H. Noel SCIENTIFIC ISSUES IN POPULATION-LEVEL ECOLOGIC RISK ASSESSMENT Density Dependence in Ecologic Risk Assessment, S.J. Moe Genetic Variation in Population-Level Ecologic Risk Assessment, D. Nacci and A. Hoffman The Spatial Structure of Populations and Ecologic Risk Assessment, W.G. Landis, and A. Deines What Conservation Biology and Natural Resource Management Can Offer Population-Level Ecologic Risk Assessment, J.A. Gervais and H.M. Regan APPROACHES TO POPULATION-LEVEL ECOLOGIC RISK ASSESSMENT Empiric Approaches to Population-Level Ecologic Risk Assessment, T.M. Carlsen, P.F. Chapman, S. Brassfield, N. Elmegaard, A. Hoffman, W. Landis, S. J. Moe, D. Nacci, H.M. Noel, and J. Spromburg Modeling Approaches to Population-Level Ecologic Risk Assessment, W.R. Munns, Jr., J.A. Gervais, A.A. Hoffman, U. Hommen, D.E. Nacci, M. Nakamaru, R. Sibly, and C.J. Topping A Framework for Population-Level ERA, R. Wentsel, N. Beyer, V. Forbes, S. Maund, and R. Pastorok A PATH FORWARD Issues and Recommendations, W.R. Munns, Jr, L.W. Barnthouse, and M.T. Sorensen REFERENCES AND APPENDICES References Appendix 1 Decision Context Scenarios Appendix 2 Workshop Exercise: Application of 2 Modeling Techniques in a Theoretical Assessment for Agricultural Pesticide Registration Appendix 3 Supplemental Reading List

In this chapter, the author summarizes the principle issues remaining for full implementation and acceptance of population-level ecological risk assessment. A goal of protecting the population as a valued resource, or of minimizing the adverse effects of some environ mental stressor, may necessitate information about chemical, Issues and Recommendations biological, and physical components required to support the assessment population. An issue for any assessment is the relative effort that should be allocated among empirical and modeling approaches for population-level ecological risk assessment. Measuring or predicting population-level effects is only part of the challenge for the risk assessment or risk management process the significance of changes in population attributes because of exposure to stressors must be interpreted to understand risks. One of the greatest outstanding challenges to acceptance of population-level ecological risk assessment as a decision support tool is its understanding and acceptance by risk managers and stakeholders.

The paper by Harwell and Gentile (2006) published in this issue of Integrated Environmental Assessment and Management (IEAM) reviews the ecological significance and persistence of impacts associated with the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska. Reviewing the considerable body of ecological, ecotoxicological, and biological studies conducted in the years preceding the oil spill and during the 17 years after the oil spill, the authors attempt to address the question often asked following environmental catastrophes similar to this one: In the years following the Exxon Valdez oil spill, are there any remaining and continuing ecologically significant exposures or effects on the Prince William Sound ecosystem directly attributable to the oil spill? We are proud to provide the peer-reviewed forum for these authors to ask and answer this important scientific question. The mission of a scientific journal is to publish manuscripts that are consistent with the scope of the journal and that have undergone a rigorous peer-review process. In the case of IEAM, the mission involves integrating scientific research with environmental management in an open forum that encourages hypothesis-testing, fosters technical discussion (including debate), and promotes new ideas and approaches to resolve difficult and complex environmental challenges. IEAM challenges scientists and environmental managers to ask and answer the ‘‘so what’’ and ‘‘what if ’’ questions. The nature and extent of residual impacts from the Exxon Valdez oil spill is the subject of significant on-going scientific, regulatory, and public debate and controversy, as demonstrated by the recent newsmagazine article appearing in Time (Caplan 2006) in recognition of the anniversary of the oil spill. Consistent with the high standards of peer-review required by the Society of Environmental Toxicology and Chemistry (SETAC) and its members and recognizing the varied and strongly-held viewpoints surrounding this anniversary, the manuscript submitted by Harwell and Gentile was reviewed by 16 anonymous reviewers, including several members of the IEAM Founding Editorial Board. The authors are commended for their patience and their careful attention to comments and criticisms raised by reviewers during the preparation of their final manuscript. The final acceptance and publication of the Harwell and Gentile paper reflects a determination by the Editor-in-Chief and the Founding Editorial Board that the paper is substantive and worthy of publication. The publication of this paper does not, however, imply that IEAM endorses the authors’ findings as scientific truth. The paper reflects the authors’ interpretations of the extraordinarily comprehensive set of ecological studies performed following the oil spill. The Founding Editorial Board is aware that others may have different interpretations of the same studies, and that others may be able to point to different studies supporting contrary interpretations and conclusions. It is our hope and expectation that publication of the Harwell and Gentile paper will stimulate a productive, scientific debate concerning the nature of the residual impacts remaining nearly 2 decades after the Exxon Valdez oil spill and about the prognosis for continued recovery of the Prince William Sound ecosystem. The Founding Editorial Board of IEAM invites reaction to this paper and additional analysis that contributes to assessment of the ecological status of Prince William Sound; we will consider them in future issues of the journal, in accordance with our peer-review process. It is only by examination of the successes and weaknesses of our collective responses to the oil spill that we might learn from the event, avoid mistakes (if any), and improve our ability to respond to similar catastrophes in the future.

Ecological effects of modern agrochemicals are typically limited to brief episodes of increased mortality or reduced growth that are qualitatively similar to natural disturbance regimes. The long-term ecological consequences of agrochemical exposures depend on the intensity and frequency of the exposures relative to the rates of recovery of the exposed populations. This paper explores the feasibility of using readily available life history information to quantify recovery rates of aquatic populations. A simple modeling framework based on the logistic population growth model is used to compare population recovery rates for different types of organisms and to evaluate the influence of life history, initial percent reduction, disturbance frequency, and immigration on the time required for populations to recover from simulated agrochemical exposures. Recovery models are developed for aquatic biota ranging in size and longevity from unicellular algae to fish and turtles. Population growth rates and recovery times derived from life history data are consistent with measured recovery times reported in mesocosm and enclosure experiments, thus supporting the use of the models for quantifying population recovery rates for ecological risk assessment.