Risk Analysis Framework for Informing Endangered Species

Chapter 17

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A Causal/Risk Analysis Framework for Informing Endangered Species Jeopardy Reviews for Pesticides Nicholas W. Gard*,1 and Charles A. Menzie2 1Exponent 2Exponent

Inc., 5375 SE 30th Place, Suite 250, Bellevue, WA 98007 Inc., 1800 Diagonal Rd., Suite 500, Alexandria, VA 22314 *E-mail: [email protected]

A framework is proposed for evaluating the relative importance of select pesticides as sources of risks to the viability of endangered species. The framework is based on a causal/risk analysis approach that has been modified to be more specific to pesticides and endangered species matters. A step-wise process is proposed that involves the identification of candidate stressors including the pesticides in question, development of a comprehensive conceptual model that illustrates how the stressors may impact the endangered species (directly or indirectly), and application of criteria for judging the weight-of-evidence. The process yields outcomes that rank stressors. This allows for evaluation of pesticides in relation to other stressors to determine whether the select pesticides are affecting or may pose a risk to population viability and also to guide the development of species conservation plans. An example is provided for the kit fox, an endangered species, and a suggestion is made to conduct a collaborative project involving the Services (U.S. Fish and Wildlife Service, National Marine Fisheries Service), the U.S. Environmental Protection Agency, and the pesticide industry.

© 2012 American Chemical Society In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


Introduction This paper presents a framework for using formal causal/risk analysis to evaluate the potential importance of pesticides as stressors that may increase the risk of extinction of endangered species in areas where there is overlap between those populations and the influence of the pesticides. The approach includes causal elements, because it presumes that historical or existing stressors have contributed to the endangerment of a species; the approach also includes risk elements, because some applications concern whether or not a pesticide could contribute further to endangerment. In some cases, the pesticides under evaluation are already present, while in others, they may be introduced. The purpose of the framework is to provide a means of judging the potential significance of particular pesticides under regulatory review. Such reviews are of particular import when considering potential effects on endangered species, and the framework is designed to provide a means of classifying such effects. It is also intended to highlight actions that may be most valuable for conservation plans. The proposed framework is intended to be used for evaluations that would benefit from greater structure, quantification, and clarity. There may be instances where simpler methods of evaluation suffice to answer management questions. The framework is premised on the recognition that time to extinction can be influenced by a number of stressors, some of which may be especially important, while others may be less important and still others may be negligible (1, 2). The relative importance of existing stressors can be assessed using causal analysis, an approach that has a long history of assisting health and environmental professionals in differentiating among causes of an illness or environmental impairment (3–5). A well-structured causal analysis can guide the collection and use of information needed to answer questions about causes/stressors, as well as their relative importance (5). With regard to questions concerning the viability of endangered species and the assessment of pesticides and other stressors, a causal analysis serves to: 1) guard against gaps in logic concerning candidate causes and effects; 2) provide transparency for “professional judgment” and scientific opinions; 3) identify principal causes/stressors that affect population viability and that could be mitigated; and 4) distinguish among negligible, minor, and major causes/stressors. A causal analysis enables stakeholders to be more easily engaged in the assessment of information and using it to support conclusions or guide mitigation measures. In cases where a new stressor such as a pesticide is introduced, the framework can guide the risk assessment aspects of the analysis and help answer questions as to whether the introduced stressor would be negligible, minor, or a possible major stressor. This aspect of the risk assessment for a pesticide would account for the existing stressors and the role they have played or are playing with respect to endangerment. The proposed application of causal/risk assessment to pesticide assessments is derived from existing causal analysis methods that have been used to judge biological impairments in water bodies and have been used in one case to evaluate potential chemical stressors on the kit fox, an endangered species (6). We recognize that stresses on salmonids in the Pacific Northwest has been a matter of great interest with regard to the role that pesticides may play in influencing 244 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


the risk of extinction. It is notable that causal analysis has been applied in a limited way to this matter. Wiseman et al. (7) explored seven candidate causes of biological impairment involving salmonids in the Touchet River (Washington, USA): 1) unspecified toxicity, 2) warmer temperature, 3) increased sedimentation, 4) decreased DO, 5) increased pH, 6) reduced detrital food, and 7) reduced habitat complexity. In this paper, we first provide an overview of the proposed framework. We then provide an example of an actual application of causal analysis to an endangered species matter.

Proposed Framework We propose an approach that ranks the contribution of pesticides to extinction risk for selected endangered species. For example, the pesticides could be sorted into three categories based on their contribution to extinction risk: “negligible cause/stressor,” “minor cause/stressor,” or “major cause/ stressor.” These categories and terms are simply suggestions, and greater discussion is needed to agree on a classification system. However, the principle idea is to have a classification system that allows regulators and others to understand the relative importance of a particular pesticide to a specified endangered species. This provides more insight than a binary-risk vs. no-risk conclusion. The proposed seven-step causal/risk analysis framework (Figure 1) is patterned after that developed by EPA (4) for assessing causes of environmental impairments in water bodies. The framework is intended to support Section 7 consultations with the Services (U.S. Fish and Wildlife Service, National Marine Fisheries Service) regarding endangered species and the EPA regulatory process for pesticide registration. To that end, the framework lays out a process for categorizing stressors with respect to their influence on the time to extinction of the endangered species. Non-pesticide stressors with a potentially high impact are included, so that the added stress or risk from pesticide exposure can be appropriately and parsimoniously evaluated. As noted, the casual analysis framework is intended to support judgments concerning the relative significance of pesticides; this can involve classifying pesticides as negligible, minor, or major with respect to the stress or risk they pose for time of extinction of an endangered species. While the ultimate focus is on the role that pesticides have played or may yet play with respect to the time to extinction of a species, it is helpful, whenever possible, to identify all major stressors and to have an understanding of their roles. An explicit consideration of these alternative causes is valuable, because it makes the casual/risk analysis approach beneficial beyond the immediate question of answering specific questions regarding whether or not a pesticide is a contributing factor. A broader process that considers the range of alternative causes is more likely to be accepted than a process focused exclusively on one stressor. That said, the intent of the process is to enable a determination to be made about pesticides and their contribution to endangerment. The steps in the process are described in the following sections. 245 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


Figure 1. Causal/risk analysis approach. This first step of the causal/risk analysis describes the goals and objectives of the assessment. It further specifies several key aspects of the assessment. These include: 1) identification of the endangered species, 2) identification of the pesticides being evaluated, 3) descriptions of the spatial and temporal characteristics of the assessment with regard to the species populations and the influences of the pesticide(s), and 4) an overview of the plan for applying causal/risk analysis. This step is similar in many respects to the problem formulation step used in ecological risk assessment (8), and guidance that has been developed for that purpose can be helpful for completing this step of the analysis. The second step is to characterize the species’ biological characteristics and ecological requirements. This step helps identify a species’ vulnerabilities to various stressors. Relevant information used at this step includes life history characteristics and ecological and habitat requirements, with an emphasis on the characterization of critical habitat. Demographic information should also be included. The characterization of the species biology should include information on what is known about the cause(s) of the decline in the species population (required detail in the species listing document or recovery plans). The identification of candidate causes of population declines, along with stressors that might influence recovery, is a key part of the second step of the analysis. For pesticide evaluations, including Section 7 consultations, the pesticides in question would be included along with the other candidate causes/stressors. The list should include the most obvious causes/stressors, as 246 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


well as those that may be possible based on general knowledge or that may be of particular concern to trustees and/or stakeholders but whose causal relationship is not known. For most threatened and endangered species, a starting list of stress factors can be found in the species recovery plan drafted by the U.S. Fish and Wildlife Service. For guidance on development of a list of candidate causes, the following categories from the Endangered Species Act are helpful: 1) the present or threatened destruction, modification, or curtailment of its habitat or range; 2) overutilization for commercial, recreational, scientific, or educational purposes; 3) disease or predation; 4) inadequacy of existing regulatory mechanisms; and 5) other natural or manmade factors affecting its continued existence. Other categories that are relevant to the assessment of chemicals would include “pesticides” and “other toxic chemicals.” These should be included among the basic categories because of the need to consider toxic chemicals in the assessment of potential stressors. Once the comprehensive list of potential causes/stressors related to a species decline has been prepared, a conceptual model is developed to illustrate the relationships between the causes/stressors and the species of concern; this is key to the process of prioritizing the stress factors. Life history stages should be examined separately, because vulnerability to a stress factor may differ as a result of different physiology and/or behaviors associated with different life stages. Temporal aspects are important for determining whether the stressor is present when the organisms are present, which life stage is likely to be most exposed, and if the cause/stressor is expected to persist indefinitely. The relative magnitudes of the stressors on life stages are also identified in the conceptual model. For example, if one stressor has a slight effect on a life stage but not necessarily on overall lifespan, while another has a substantial effect in shortening lifespan, then the latter is considered to be a potentially more significant stressor than the former. If known, the causal mechanism by which a stressor affects a life stage should also be stated at this step. This provides insight into the significance of the stressor and can be important for identifying stressors that have potential additive, antagonistic, or synergistic effects. This statement could be relatively general, such as, “Toxicant reduces survival of eggs and larvae.” Such statements should be supported by references to the relevant literature. Both direct effects of stressors (those that act directly on the species of concern) and indirect effects (such as reducing the species’ food supply or increasing predators) should be included in the conceptual model and evaluation. Only those causes/stressors that are known to affect the species of concern either directly or indirectly should be included. Following the development of a list of potential causes/stressors that have a reasonable possibility of affecting a threatened or endangered species, including the pesticide in question, it is necessary to establish a relative ranking of threats, so that time-to-extinction estimates can include influences of the most important stressors. New and emerging threats such as climate change can also be quantified and prioritized at this time. Population declines for endangered species are usually related to combinations of stressors, and the proposed framework is designed to distinguish among causes/stressors that are major, minor, and negligible in either reducing populations of endangered species and/or limiting the ability of these 247 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

populations to recover. The premise for judging a pesticide as a negligible stressor is that it will not decrease the time to extinction for the relevant endangered species under the current management plans. To implement the method, we propose criteria for the classification of stressors. We recognize that this is an initial classification and will need to be reviewed and modified by stakeholders. However, it serves as a starting point. •


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Major Cause/Stressor—there is convincing evidence that this is one of the causes/stressors that has led to the decline of the species population, is impeding the recovery of that species, or may cause further decline and/or impede recovery. Minor Cause/Stressor—there is convincing evidence that this is not a Major Cause/Stressor. However, there is some evidence that this cause/ stressor has or may contribute to a population decline by causing a small negative change in a demographic characteristic that is ecologically meaningful to the species in question. Because this is a minor cause/ stressor, manipulation of exposure or stress will not change the extinction risk in the absence of management of major causes/stressors. Negligible Cause/Stressor—there is convincing evidence that stress is too small to cause a change in demographic characteristics of the population.

The causal/risk analysis approach should also consider the possibility of cumulative risks from multiple stressors and distinguish which of the existing or potential future stressors are most likely to interact adversely with the proposed action. The preferred approach for accomplishing this is to relate all stressors to changes in fitness parameters, specifically to reproduction and survival rates, as well as those that potentially influence dispersal. However, this approach requires knowledge of the stressor-response relationship; i.e., how a particular magnitude of the stressor produces a specific change in the survival or reproduction of the species of concern, which is not always available in a quantitative fashion. The relative risk model (9) or a formal weight-of-evidence approach (10) can be used for initial ranking of the stress factors on a qualitative basis. Menzie et al. (5) have also outlined a step-wise approach for considering the cumulative effects of multiple stressors, and that methodology has been adapted to the proposed framework. The approach uses a “+” and “–” scoring system based on the degree of confidence in the supporting weight of evidence (6, 11): +++ convincingly supports – – – convincingly weakens ++ strongly supports – – strongly weakens + somewhat supports – somewhat weakens 0 neither supports or weakens NE no evidence 248 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

The framework relies on Hill’s criteria, as adapted by Wickwire and Menzie (12) and Suter et al. (13), as a means of evaluating the strength of evidence for ecological applications. These criteria and their application to pesticides and other stressors are described below.


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Complete causal linkage(s): A complete causal linkage requires evidence to support the various linkages that connect pesticides and other stressors as candidate causes with demographic factors believed to contribute to the decline of the species (i.e., reductions in reproduction, survival, growth, or dispersal rates). Spatial and temporal considerations are important for judging causal linkages. Strength of association: This criterion refers to the degree to which population declines can be related to one or more of the stressors. This is typically an analysis informed by knowledge of the association, as well as statistical analysis that can be supported by models. Some stressors may be strongly associated with population abundance or with changes in demographic characteristics related to population viability, while others may be weak and still others may be negligible. The types of evidence used to judge relationships will vary among stressors and will be guided by the nature of the causal relationships illustrated in the conceptual model. Consistency of association: This refers to the larger body of scientific observation concerning the relationships among candidate causes/stressors and the demographic factors that have been identified as contributing to the decline of populations of the endangered species and species that share biological and ecological characteristics. Evidence is stronger if the relationship has been observed elsewhere. If there is a lack of field observations on relationships between particular causes/stressors and the decline of a species and/or ability to recover, then the evidence for the particular cause is weakened. Care must be taken to distinguish between hypotheses and demonstrated relationships. The former are weaker than the latter. Specificity of the relationship: Specificity of effects can be useful for distinguishing among causes/stressors. For example, if a pesticide has a very specific effect on a demographic factor, and that type of effect may be contributing to the species’ decline or reducing its ability to recover, that would be stronger evidence than an effect that could be caused by a number of candidate stressors. Temporality: This criterion relates to the need for the candidate cause/stressor to precede or be coincident with the effect. This is especially important for distinguishing major causes/stressors from minor or negligible causes/stressors. For example, in the case of pesticides, if population declines preceded the use of particular pesticides, then it cannot be concluded that the pesticides were a major source of that decline. They could still, however, influence the ability of the species to recover. Temporality is also important to consider with regard to the 249 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


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timing of stressors—such as seasonal or pulse stressors—and the timing of demographic factors that are important to the species (spawning, reproduction, growth of young, and survival of adults). Evidence is stronger if the candidate cause/stress precedes the response and/or is occurring coincident with the demographic characteristics considered most important for sustaining or increasing population viability. If the cause/stress follows the decline, and/or if it is out of phase with factors influencing population viability, then the evidence is considered weak. Gradients of “response”: This relates to spatial considerations between candidate causes/stressors and the responses of the population. In the case of pesticides, this would typically involve examining the spatial patterns of either measures of exposure or effects in relation to the distribution of the pesticides. For other candidate causes/stressors, the analyses would involve similar evaluations. For example, patterns of predation pressure or losses of spawning areas resulting from habitat modification are amenable to spatial analysis. GIS and other mapping methods are typically used to examine spatial patterns. Plausibility (mechanistic basis): Evidence is stronger if the relationship between the cause/stress and the effect on the endangered species includes a plausible mechanism. This is especially important for cases where time and space relationships appear to be present, but the nature of the connection is otherwise unclear. Plausible effects can be direct or indirect (e.g., through reduction in food). For a mechanism to be plausible, evidence needs to point to an explanatory basis for population decline or constraint on recovery and how the cause/stressor relates to that explanation. More specific explanations provide stronger lines of evidence. In contrast, if there is not a plausible explanation (especially considering other criteria), then the lack of evidence would weaken the nexus between cause/stressor and effect. Coherence with facts or theory: This criterion relates to the larger body of information about how particular causes/stressors affect populations. In general, these reflect comprehensive studies related to developing facts about population-level effects and theories related to the decline of populations of particular species. Experiment: This criterion relates to manipulations and experiments that have been carried out to examine responses. For example, there may be recovery plans or control measures that provide insight into population responses following specific removal or modification of causes/stressors. An example is the coyote control program in the case of the kit fox example discussed later in this paper. This control program was followed by an increase in kit fox abundance. The manipulation lent credence to the conclusion that reduced prey abundance caused by the presence of coyote was the primary cause of kit fox decline. Analogy: This criterion draws from experience that may be considered analogous to the current evaluation.

250 In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

While we outline a particular set of criteria, these are not the only ones that might be used. Cormier et al. (14) recently identified six fundamental causal characteristics that are similar to Hill’s criteria and that could support an evaluation for the potential significance of stressors on endangered species. These could serve as an alternative means of evaluating information related to pesticides and other causes/stressors:

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Time Order: The effect cannot precede the cause. Logically then, the causal event occurs before the event that constitutes the effect. Co-Occurrence: Because the causal agent/stressor and affected entities must have interacted, they must have co-occurred in space and time. Co-occurrence does not require physical contact, and it may refer to co-occurrence with the absence of something. Also, time lags and movements of organisms are important considerations when evaluating co-occurrence. Preceding Causation: Each causal relationship is a result of a larger web of cause-and-effect relationships. Evidence of the network or pathways that preceded the causal relationship under investigation increases confidence that the causal event actually occurred. Sufficiency: The intensity, frequency, and duration of the cause/ stressor are adequate to produce the magnitude of the effect, given the susceptibility of the entity. Interaction: The cause/stressor physically interacts with the entity in a way that induces the effect. Alteration: The entity is changed by the interaction with the cause/stressor. The alteration defines the effect that prompted the causal assessment and may provide evidence in the form of symptoms or other characteristic responses.

Example Application of Causal Analysis for an Endangered Species To illustrate the methodological concept of causal analysis, we use as an example the application of causal analysis to evaluate a decline in the population of the endangered San Joaquin kit fox population on the Elk Hills Naval Petroleum Reserve #1 in California (6), which was observed between 1981 and 1986. This precipitous decline was a cause for concern at the time because of its magnitude and because it was associated with an increase in oil production on the site.



The causal analysis followed the methodology described above. However, we use the terms major, minor, and negligible in the case example and base these designations on the explanatory text in the EPA case study (6). Fifteen types of evidence were used to evaluate the contributions from the six categories of stressors. Based on this analysis, the overall weight of evidence supported the conclusion that predation by coyotes was the major cause of the decline. Road kills contributed to the high mortality of foxes, but were much less common and are considered a minor cause. The decline in prey probably contributed to mortality by making the foxes more susceptible to predation and, as such, was a major indirect cause. However, the decline in prey with respect to food availability was considered a minor cause. As a model for causal analysis at contaminated sites, this study was successful at sorting the causes into categories useful for management. Contaminants were found to be a negligible cause, and an alternative cause—predation by coyotes—was strongly supported by the evidence. EPA (6) summarized their analyses in a table that presented the weight of evidence for or against the various candidate stressors contributing to the decline of the kit fox population (Table I). Evidence supporting a candidate stressor as a cause of kit fox population decline was designated with one or more plusses (+), while evidence against a stressor was designated with one or more minuses (–). Four of the stressors—predation, toxics, accidents, and disease—act directly on the kit fox population, because they remove animals from the population and thereby reduce reproductive success. For this case study, there was a particular interest in the potential role of toxics, because this candidate stressor prompted the causal analysis. The stressors of prey and habitat could affect the kit fox population indirectly, because these reflect basic needs of the kit fox population. EPA distinguished between habitat-related stressors that were associated with disturbance and climate (6). This type of distinction can be important for identifying proximal causes. The weight-of-evidence table is interpreted, in part, by examining the consistency of the evidence across each candidate cause. For example, positive or neutral pieces of evidence would support a candidate cause to a greater degree relative to causes for which the evidence is mixed or negative. Consistent negative evidence can be used to eliminate a cause. As Table I shows, with the exception of predation, the evidence was somewhat inconsistent for all of the candidate causes. The consistency of evidence for predation contributed to the conclusion that this was a major cause. Interpretation of the table also includes considering explanations for the inconsistencies. If inconsistencies in evidence can be explained for a particular candidate cause, that can help strengthen the basis for a conclusion regarding that cause. To that end, EPA developed explanations for three candidate causes—habitat modification, prey abundance, and vehicular activity—that involved converting them from candidate causes to contributors to the most likely cause.


Table I. Example presentation of evidence for an endangered species causal analysis: Decline of the kit fox (6)

253


Comparison of the Strength of Evidence for the Candidate Causes. Types of evidence with no evidence for any candidate cause were excluded. Prey Types of Evidence

Disturbance

Habitat Climate

Disturbance

Climate

+

–

Predation

Toxics

Accidents

Disease

+

+

+

–

0

0

NE

NE

Evidence that Uses Data from the Case ++

Spatial/Temporal Co-occurrence

–

+ 0

Temporal Sequence

0

++

Evidence of Exposure or Biological Mechanism (pathway independent) Evidence of Exposure or Bio-logical Mechanism (by pathway)

–

+

Causal Pathway

+

– +++

Stressor-Response Relationships from the Field (pathway indep.) Stressor-Response Relationships from the Field (by pathway)

–

Manipulation of Exposure

+

NE

NE

++

++

++

––

++

–

+

+

+

0

– –

0

NE

NE

NE

NE

NE

NE

+

NE

NE

NE

+

Continued on next page.

In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

Table I. (Continued). Example presentation of evidence for an endangered species causal analysis: Decline of the kit fox (6)

Prey Types of Evidence

Disturbance

Symptoms, Starvation

–

Symptoms, Reproductive (pathway independent)

+

Symptoms, Reproductive (by pathway)

+

Habitat Climate

Disturbance

Climate

NE

NE

Predation

Toxics

Accidents

Disease

NE

NE

NE

NE

–

254


Comparison of the Strength of Evidence for the Candidate Causes. Types of evidence with no evidence for any candidate cause were excluded.

In Pesticide Regulation and the Endangered Species Act; Racke, K., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


We applied our parlance to the EPA case study (6) and, based on EPA’s interpretations, designated candidate causes as either a major cause, a contributing but minor cause, or a negligible cause. An initial step in the causal analysis approach is to eliminate causes based on the available evidence. Disease as a candidate cause was considered negligible, because the evidence from the site was negative, and very few of the trapped or dead foxes were observed to be diseased. In contrast, there was strong and consistent evidence for predation (Candidate Cause 3) as the major cause. Based in part on literature and work with Tom O’Farrell, EPA learned that predation by coyotes is the major cause of death in kit foxes. They also found that this is the case elsewhere, an observation that further supported coyote predation as a major cause. In contrast, while evidence for vehicular accidents is also positive, the mortality rate for kit foxes due to accidents is much lower than for predation, and EPA determined from modeling that it was not sufficient to account for the decline. For this reason, EPA considered vehicular accidents a contributing minor cause. EPA concluded that the evidence for environmental contaminants was inconsistent and complex and that there was no evidence that toxic exposures could account for the high mortality rates that caused the decline. Thus, toxics were considered a negligible cause. Because trapped or dead kit foxes did not exhibit signs of starvation, EPA concluded that prey availability was not a likely cause for the sudden decline in the kit fox population. In addition, there was no evidence to indicate that kit fox fecundity was influenced by spatial patterns in prey availability. However, EPA did conclude that reduced prey availability could be a contributing major cause that forced kit foxes to spend more time foraging and thus exposed them to predation and to being killed by vehicles. Habitat quality is an especially important factor for survival of kit foxes, but EPA found that the evidence was ambiguous that change in habitat quality was a factor affecting survival of kit foxes and causing their decline. While there is some evidence that shifts from undeveloped to developed areas could affect abundance, contributions of vegetated and unvegetated areas to the decline of the kit fox remain largely unknown. Based on their review of the body of evidence (Table I), EPA concluded that predation by coyotes was the major cause of the decline in the kit fox population. Notably, the kit fox decline ended after a coyote control program was instituted and coyote numbers declined. The example is illustrative of the potential value of a formal causal analysis for an endangered species matter. The elimination of toxicants and diseases as causes has practical management implications. No additional measures need be taken to eliminate exposures to toxicants or to reduce the introduction of pathogens. EPA (6) reported that the use of a formal causal analysis method provides greater assurance of the quality of the results, and that identification of the likely proximate cause provides increased confidence that the negative results for contaminants were not a result of inadequate data or analysis.



Discussion The proposed causal/risk analysis framework provides a means of organizing and evaluating scientific information related to potential risks of anthropogenic stressors to endangered species, upon which to build an assessment of whether pesticides contribute significantly to shortening the time to extinction. Based on our experience with other applications of causal analyses, we believe that application of the framework will help with the transparency of the evaluation process and will provide a means of understanding the relative significance of stressors, including pesticides. The framework presented in this paper is largely based on that developed by EPA as part of stressor identification and the CADDIS system. That approach incorporates a variety of qualitative and quantitative information to support the overall weight of evidence. There are a number of weight-of-evidence approaches that could be used to supplement the approach, but we envision those as tools that may be used for specific applications. We do think that Bayesian approaches may prove useful for organizing and quantifying the weight of evidence, and we are currently working on such applications. Within a management context regarding whether or not to use a pesticide, and perhaps how to use it, multi-criteria decision analysis (MCDA) may also prove useful. Linkov and Moberg (15) have described the application of this methodology to a broad range of case studies. Although causal analyses have been applied to endangered species, we are unaware of an application that is linked to the pesticide regulatory review process and Section 7 consultation. A logical next step is to carry out such an application of causal/risk analysis of a pesticide as a pilot project. While this can be accomplished as a technical exercise for illustration purposes, we envision that the most effective applications will be those that occur as part of a collaborative assessment effort involving the Services, EPA, and the pesticide industry. This can be accomplished by following the steps outlined in this paper. A collaborative approach will involve identifying and agreeing on criteria for judging information and on judging how to rank stressors. Based on experience elsewhere, this type of collaboration has been shown to be effective for developing a shared understanding of the assessment process and of the analyses.

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U.S. EPA. Analysis of the causes of a decline in the San Joaquin kit fox population on the Elk Hills, Naval Petroleum Reserve #1, California, EPA/600/R-08/130; U.S. Environmental Protection Agency, National Center for Environmental Assessment, Office of Research and Development: Cincinnati, OH, 2008. Wiseman, C. D.; LeMoine, M.; Cormier, S. M. Hum. Ecol. Risk Assess. 2010, 16, 87–115. U.S. EPA. Guidelines for ecological risk assessment, EPA/630/R-95/002F; U.S. Environmental Protection Agency, Risk Assessment Forum: Washington, DC, 1998. Regional Scale Ecological Risk Assessment Using the Relative Risk Model; Landis, W. G, Ed.; CRC Press: Boca Raton, FL, 2005. Linkov, I.; Loney, D.; Cormier, S.; Satterstrom, F. K.; Bridges, T. Sci. Total Environ. 2009, 407, 5199–5205. U.S. EPA. CADDIS: The causal analysis/diagnosis decision information system; U.S. Environmental Protection Agency, 2011. Accessed August, 17, 2011, http://www.epa.gov/caddis/. Wickwire, T.; Menzie, C. A. Hum. Ecol. Risk Assess. 2010, 16, 10–18. Suter, G. W.; Norton, S. B.; Cormier, S. M. Hum. Ecol. Risk Assess. 2010, 16, 19–34. Cormier, S. M.; Suter, G. W.; Norton, S. B. Hum. Ecol. Risk Assess. 2010, 16, 53–73. Linkov, I.; Moberg, E. Multi-Criteria Decision Analysis: Environmental Applications and Case Studies (Environmental Assessment and Management); Boca Raton, FL: CRC Press. 2011, 204 p.


Risk Analysis Framework for Informing Endangered Species

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