Amelie Schmolke | University of Nebraska Lincoln (original) (raw)
Papers by Amelie Schmolke
Ecotoxicology, Jul 25, 2023
Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protec... more Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protection products. These model ecosystems allow researchers to capture interactions of multiple species under realistic environmental conditions. They enable assessment of direct and indirect effects of stressors at all trophic levels (i.e., from primary producers to secondary consumers) and impacts on ecosystem functions. Due to the limited ability to test the multitude of potential exposure scenarios, cross-linking aquatic mesocosm studies with virtual mesocosms, i.e., aquatic system models (ASMs), can serve to meet the demand for more environmental realism and ecological relevance in risk assessment. In this study, full control data sets from seven aquatic mesocosm studies conducted at a single test facility under GLP were analysed graphically and using descriptive statistics. Thereby, not only a comprehensive data base but also an insight into the species present, their dynamics over time, and variability in unchallenged mesocosms was observed. While consistency in dynamics could be discerned for physical and chemical parameters, variability was evident for several biological endpoints. This variability points to amplification of small differences over time as well as to stochastic processes. The outline of existing gaps and uncertainties in data leads to the estimation of what can be expected to be captured and predicted by ASMs.
Environmental Toxicology and Chemistry, Sep 22, 2020
Large‐scale colony feeding studies (LSCFSs) aim to assess potential pesticide exposure to and eff... more Large‐scale colony feeding studies (LSCFSs) aim to assess potential pesticide exposure to and effects on honey bees at the colony level. However, these studies are sometimes affected by high losses of control colonies, indicating that other stressors may impact colonies and confound the analysis of potential pesticide impacts. We assessed the study design and environmental conditions experienced by the untreated control colonies across 7 LSCFSs conducted in North Carolina (USA). Overwintering success differed considerably among the studies, as did their initial colony conditions, amount and timing of sugar feeding, landscape composition, and weather. To assess the effects of these drivers on control colonies' overwintering success, we applied the mechanistic colony model BEEHAVE. Sugar feedings and initial status of the simulated colonies were more important for fall colony condition than were landscape and weather. Colonies that had larger colony sizes and honey stores in the fall were those that began with larger honey stores, were provided more sugar, and had supplemental feedings before the fall. This information can be used to inform the standardization of a study design, which can increase the likelihood of overwintering survival of controls and help ensure that LSCFSs are comparable. Our study demonstrates how a mechanistic model can be used to inform study designs for higher tier effects studies. Environ Toxicol Chem 2020;39:2286–2297. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Environmental Modelling and Software, Feb 1, 2021
The acceptance and usefulness of simulation models are often limited by the efficiency, transpare... more The acceptance and usefulness of simulation models are often limited by the efficiency, transparency, reproducibility, and reliability of the modelling process. We address these issues by suggesting that modellers (1) "trace" the iterative modelling process by keeping a modelling notebook corresponding to the laboratory notebooks used by empirical researchers, (2) use a standardized notebook structure and terminology based on the existing TRACE documentation framework, and (3) use their notebooks to compile TRACE documents that supplement publications and reports. These practices have benefits for model developers, users, and stakeholders: improved and efficient model design, analysis, testing, and application; increased model acceptance and reuse; and replicability and reproducibility of the model and the simulation experiments. Using TRACE terminology and structure in modelling notebooks facilitates production of TRACE documents. We explain the
The role of ecological models in linking ecological risk assessment to ecosystem services in agro... more The role of ecological models in linking ecological risk assessment to ecosystem services in agroecosystems
Environmental Modelling & Software, 2021
The acceptance and usefulness of simulation models are often limited by the efficiency, transpare... more The acceptance and usefulness of simulation models are often limited by the efficiency, transparency, reproducibility, and reliability of the modelling process. We address these issues by suggesting that modellers (1) "trace" the iterative modelling process by keeping a modelling notebook corresponding to the laboratory notebooks used by empirical researchers, (2) use a standardized notebook structure and terminology based on the existing TRACE documentation framework, and (3) use their notebooks to compile TRACE documents that supplement publications and reports. These practices have benefits for model developers, users, and stakeholders: improved and efficient model design, analysis, testing, and application; increased model acceptance and reuse; and replicability and reproducibility of the model and the simulation experiments. Using TRACE terminology and structure in modelling notebooks facilitates production of TRACE documents. We explain the
Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protec... more Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protection products. These model ecosystems allow to capture interactions of multiple species under environmental conditions. They enable assessment of direct and indirect effects of stressors at all trophic levels and impacts on ecosystem functions. Due to the limited ability to test the multitude of potential exposure scenarios, cross-linking aquatic mesocosm studies with virtual mesocosms, i.e. aquatic system models (ASMs), can serve to meet the demand for more environmental realism and ecological relevance in risk assessment. In this study, full control data sets from seven aquatic mesocosm studies conducted at a single test facility under GLP are graphically analysed. Thereby, not only a comprehensive data base but also an insight into the species present, their dynamics over time and variability in unchallenged mesocosms is provided. While consistency in dynamics could be discerned for p...
PLOS ONE, Jan 24, 2013
Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic i... more Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic insects. Dispersal is often the limiting factor for successful re-colonization and recovery of stressed habitats. Therefore, in this study, we evaluated the effects of landscape permeability, assuming a combination of riparian vegetation (edge permeability) and other vegetation (landscape matrix permeability), and distance between waterbodies on the colonization and recovery potential of weakly flying insects. For this purpose, we developed two models, a movement and a population model of the non-biting midge, Chironomus riparius, an aquatic insect with weak flying abilities. With the movement model we predicted the outcome of dispersal in a landscape with several linear water bodies (ditches) under different assumptions regarding landscapedependent movement. Output from the movement model constituted the probabilities of encountering another ditch and of staying in the natal ditch or perishing in the landscape matrix, and was used in the second model. With this individualbased model of midge populations, we assessed the implications for population persistence and for recovery potential after an extreme stress event. We showed that a combination of landscape attributes from the movement model determines the fate of dispersing individuals and, once extrapolated to the population level, has a big impact on the persistence and recovery of populations. Population persistence benefited from low edge permeability as it reduced the dispersal mortality which was the main factor determining population persistence and viability. However, population recovery benefited from higher edge permeability, but this was conditional on the low effective distance that ensured fewer losses in the landscape matrix. We discuss these findings with respect to possible landscape management scenarios.
Frontiers in Ecology and Evolution
IntroductionHabitat restoration aims at reinstating abiotic and biotic habitat conditions to supp... more IntroductionHabitat restoration aims at reinstating abiotic and biotic habitat conditions to support long-term species persistence and viability. This management practice is commonly part of recovery plans developed for species listed as threatened or endangered under the Endangered Species Act. The endangered Topeka shiner (Notropis topeka) inhabits off-channel habitats, such as oxbow lakes which are increasingly the focus of restoration, but the exact abiotic conditions conducive to its persistence in this habitat are not fully understood. In this study, a hybrid model consisting of an individual-based model of the Topeka shiner and an aquatic ecosystem model representing the oxbow habitat was applied to identify optimal environmental conditions for the persistence of Topeka shiner populations.Materials and methodsEnvironmental conditions that correlated with Topeka shiner presence were gathered from published studies and included water temperature, turbidity, oxbow depth, light i...
Environmental Toxicology and Chemistry
The occurrence of some species listed under the United States' Endangered Species Act in agri... more The occurrence of some species listed under the United States' Endangered Species Act in agricultural landscapes suggests that their habitats could potentially be exposed to pesticides. However, the potential effects from such exposures on populations are difficult to estimate. Mechanistic models can provide an avenue to estimating the potential impacts on populations, considering realistic assumptions about the ecology of the species, the ecosystem it is part of, and the potential exposures within the habitat. In the present study, we applied a hybrid model of the Topeka shiner (Notropis topeka), a small endangered cyprinid fish endemic to the US Midwest, to assess the potential population‐level effects of realistic exposures to a fungicide (benzovindiflupyr). The Topeka shiner populations were simulated in the context of the food web found in oxbow habitats that are the focus of ongoing habitat restoration efforts for the species. We applied realistic, time‐variable exposure scenarios and represented lethal and sublethal effects to individual Topeka shiners using toxicokinetic–toxicodynamic models. With fish in general showing the highest sensitivity to the compound, direct effects on simulated Topeka shiner populations governed the population‐level effects. We characterized the population‐level effects of different exposure scenarios with exposure multiplication factors (EMFs) applied. The introduction of a vegetative filter strip (VFS; 15 ft; 4.6 m) between the treated area and the oxbow habitat was shown to be effective as mitigation because EMFs were 2 to 3 times higher than for the exposure scenario without VFS. Environ Toxicol Chem 2021;40:2615–2628. © 2021 SETAC
Environmental Toxicology and Chemistry, 2020
In pesticide risk assessments, semifield studies, such as large‐scale colony feeding studies (LSC... more In pesticide risk assessments, semifield studies, such as large‐scale colony feeding studies (LSCFSs), are conducted to assess potential risks at the honey bee colony level. However, such studies are very cost and time intensive, and high overwintering losses of untreated control hives have been observed in some studies. Honey bee colony models such as BEEHAVE may provide tools to systematically assess multiple factors influencing colony outcomes, to inform study design, and to estimate pesticide impacts under varying environmental conditions. Before they can be used reliably, models should be validated to demonstrate they can appropriately reproduce patterns observed in the field. Despite the recognized need for validation, methodologies to be used in the context of applied ecological models are not agreed on. For the parameterization, calibration, and validation of BEEHAVE, we used control data from multiple LSCFSs. We conducted detailed visual and quantitative performance analyses as a demonstration of validation methodologies. The BEEHAVE outputs showed good agreement with apiary‐specific validation data sets representing the first year of the studies. However, the simulations of colony dynamics in the spring periods following overwintering were identified as less reliable. The comprehensive validation effort applied provides important insights that can inform the usability of BEEHAVE in applications related to higher tier risk assessments. In addition, the validation methodology applied could be used in a wider context of ecological models. Environ Toxicol Chem 2020;39:2269–2285. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Integrated Environmental Assessment and Management, 2019
Despite widespread acceptance of the utility of population modeling and advocacy of these approac... more Despite widespread acceptance of the utility of population modeling and advocacy of these approaches for a more ecologically relevant perspective, they are not routinely incorporated in ecological risk assessments (ERA). A systematic framework for situation-specific model development is one of the major challenges to broadly adopting population models in ERA. As risk assessors confront the multitude of species and chemicals requiring evaluation, an adaptable stepwise guide for model parameterization would facilitate this process. Additional guidance on interpretation of model output and evaluating uncertainty would further contribute to establishing consensus on good modeling practices. We build on previous work that created a framework and decision guide for developing population models for ERA by focusing on data types, model structure, and extrinsic stressors relevant to anuran amphibians. Anurans have a unique life cycle with varying habitat requirements and high phenotypic plasticity. These species belong to the amphibian class, which is facing global population decline due in large part to anthropogenic stressors, including chemicals. We synthesize information from databases and literature relevant to amphibian risks to identify traits that influence exposure likelihood, inherent sensitivity, population vulnerability, and environmental constraints. We link these concerns with relevant population modeling methods and structure in order to evaluate pesticide effects with appropriate scale and parameterization. A standardized population modeling approach, with additional guidance for anuran ERA, offers an example method for quantifying population risks and evaluating long-term impacts of chemical stressors to populations.
Environmental Toxicology and Chemistry, 2019
This work represents a collaboration among Cardno, Incorporated, Waterborne Environmental Incorpo... more This work represents a collaboration among Cardno, Incorporated, Waterborne Environmental Incorporated, and Syngenta Crop Protection, LLC. The project was sponsored by Syngenta Crop Protection, LLC. The authors are grateful for the comments and suggestions of two anonymous reviewers, who helped improve the manuscript.
Integrated Environmental Assessment and Management, 2021
The assimilation of population models into Ecological Risk Assessment (ERA) has been hindered by ... more The assimilation of population models into Ecological Risk Assessment (ERA) has been hindered by their range of complexity, uncertainty, resource investment, and data availability. Likewise, ensuring that the models address risk assessment objectives has been challenging. Recent research efforts have begun to tackle these challenges by creating an integrated Modeling Framework and Decision Guide to aid the development of population models with respect to ERA objectives and data availability. In the Framework, the trade-offs associated with the generality, realism, and precision of an assessment are used to guide the development of a population model commensurate with the protection goal. The Decision Guide provides risk assessors with a stepwise process to assist them in developing a conceptual model that is appropriate for the assessment objective and available data. We have merged the Decision Guide and Modeling Framework into a comprehensive approach (Pop-GUIDE, Population modeling Guidance, Use, Interpretation, and Development for Ecological risk assessment) for the development of population models for ERA that is applicable across regulatory statutes and assessment objectives. In Phase 1 of Pop-GUIDE, assessors are guided through the trade-offs of ERA generality, realism, and precision, which are translated into model objectives. In Phase 2, available data are assimilated and characterized as general, realistic, and/or precise. Phase 3 provides a series of dichotomous questions to guide development of a conceptual model that matches the complexity and uncertainty appropriate for the assessment that is in concordance with the available data. This phase guides model developers and users to ensure consistency and transparency of the modeling process. We introduce Pop-GUIDE as the most comprehensive guidance for population model development provided to date. It is the first of such documents that includes an evaluation of uncertainty as a function of the tolerance of the assessment in which its applied. We demonstrate *
Ecological Modelling, 2019
The Topeka shiner, a small cyprinid fish, is a seminal example of an endangered aquatic species i... more The Topeka shiner, a small cyprinid fish, is a seminal example of an endangered aquatic species in the Midwestern USA. Populations and their associated critical habitats may experience potential direct and/or indirect effects from anthropogenic activity. However, potential impacts on fish populations from alterations in the food web are difficult to predict because they are based on complex dynamics of food web interactions. In order to simulate Topeka shiner population dynamics under different food-web scenarios, a hybrid modeling approach was developed by linking an aquatic food web model (comprehensive aquatic systems model, CASM TS) with a species-specific, individual-based population model (TS-IBM). The CASM TS was parameterized and calibrated to represent the waterbody conditions and aquatic species community in a small headwater pool in Iowa, representative of key habitat for the Topeka shiner within its geographical range. In the TS-IBM, life history, growth, and diet are represented and based on data available from the literature for the Topeka shiner and/or surrogate species. The two models are linked by the transfer of daily biomasses of Topeka shiner diet items. We simulated the effects of alterations of the food web on the Topeka shiner populations by systematically reducing the available prey base biomass. Reductions in different food groups had varying impacts on the simulated Topeka shiner populations and were dependent on the species' preference for detritus consumption. Simulations also included predation and identified predator densities to which Topeka shiner populations were vulnerable. The hybrid model provides a platform for the assessment of potential direct and food-web mediated indirect effects of stressors for the purposes of risk assessment, habitat management, and species recovery plans.
Environmental Toxicology and Chemistry, 2019
Discerning potential effects of insecticides on honey bee colonies in field studies conducted und... more Discerning potential effects of insecticides on honey bee colonies in field studies conducted under realistic conditions can be challenging because of concurrent interactions with other environmental conditions. Honey bee colony models can control exposures and other environmental factors, as well as assess links among pollen and nectar residues in the landscape, their influx into the colony, and the resulting exposures and effects on bees at different developmental stages. We extended the colony model BEEHAVE to represent exposure to the insecticide clothianidin via residues in pollen from treated cornfields set in real agricultural landscapes in the US Midwest. We assessed their potential risks to honey bee colonies over a 1-yr cycle. Clothianidin effects on colony strength were only observed if unrealistically high residue levels in the pollen were simulated. The landscape composition significantly impacted the collection of pollen (residue exposure) from the cornfields, resulting in higher colony-level effects in landscapes with lower proportions of semi-natural land. The application of the extended BEEHAVE model with a pollen exposure-effects module provides a case study for the application of a mechanistic honey bee colony model in pesticide risk assessment integrating the impact of a range of landscape compositions.
Environmental toxicology and chemistry, 2018
Population models can facilitate assessment of potential impacts of pesticides on populations or ... more Population models can facilitate assessment of potential impacts of pesticides on populations or species rather than individuals and have been identified as important tools for pesticide risk assessment of nontarget species including those listed under the Endangered Species Act. Few examples of population models developed for this specific purpose are available; however, population models are commonly used in conservation science as a tool to project the viability of populations and the long-term outcomes of management actions. We present a population model for Mead's milkweed (Asclepias meadii), a species listed as threatened under the Endangered Species Act throughout its range across the Midwestern United States. We adapted a published population model based on demographic field data for application in pesticide risk assessment. Exposure and effects were modeled as reductions of sets of vital rates in the transition matrices, simulating both lethal and sublethal effects of h...
Environmental toxicology and chemistry / SETAC, Jan 6, 2016
Although population models are recognized as necessary tools in the ecological risk assessment of... more Although population models are recognized as necessary tools in the ecological risk assessment of pesticides, particularly for species listed under the Endangered Species Act, their application in this context is currently limited to very few cases. The authors developed a detailed individual-based population model for a threatened plant species, the decurrent false aster (Boltonia decurrens), for application in pesticide risk assessment. Floods and competition with other plant species are known factors that drive the species' population dynamics and were included in the model approach. The authors use the model to compare the population-level effects of five toxicity surrogates applied to B. decurrens under varying environmental conditions. The model results suggest that the environmental conditions under which herbicide applications occur may have a higher impact on populations than organism-level sensitivities to an herbicide within a realistic range. Indirect effects may be ...
Ecotoxicology, Jul 25, 2023
Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protec... more Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protection products. These model ecosystems allow researchers to capture interactions of multiple species under realistic environmental conditions. They enable assessment of direct and indirect effects of stressors at all trophic levels (i.e., from primary producers to secondary consumers) and impacts on ecosystem functions. Due to the limited ability to test the multitude of potential exposure scenarios, cross-linking aquatic mesocosm studies with virtual mesocosms, i.e., aquatic system models (ASMs), can serve to meet the demand for more environmental realism and ecological relevance in risk assessment. In this study, full control data sets from seven aquatic mesocosm studies conducted at a single test facility under GLP were analysed graphically and using descriptive statistics. Thereby, not only a comprehensive data base but also an insight into the species present, their dynamics over time, and variability in unchallenged mesocosms was observed. While consistency in dynamics could be discerned for physical and chemical parameters, variability was evident for several biological endpoints. This variability points to amplification of small differences over time as well as to stochastic processes. The outline of existing gaps and uncertainties in data leads to the estimation of what can be expected to be captured and predicted by ASMs.
Environmental Toxicology and Chemistry, Sep 22, 2020
Large‐scale colony feeding studies (LSCFSs) aim to assess potential pesticide exposure to and eff... more Large‐scale colony feeding studies (LSCFSs) aim to assess potential pesticide exposure to and effects on honey bees at the colony level. However, these studies are sometimes affected by high losses of control colonies, indicating that other stressors may impact colonies and confound the analysis of potential pesticide impacts. We assessed the study design and environmental conditions experienced by the untreated control colonies across 7 LSCFSs conducted in North Carolina (USA). Overwintering success differed considerably among the studies, as did their initial colony conditions, amount and timing of sugar feeding, landscape composition, and weather. To assess the effects of these drivers on control colonies' overwintering success, we applied the mechanistic colony model BEEHAVE. Sugar feedings and initial status of the simulated colonies were more important for fall colony condition than were landscape and weather. Colonies that had larger colony sizes and honey stores in the fall were those that began with larger honey stores, were provided more sugar, and had supplemental feedings before the fall. This information can be used to inform the standardization of a study design, which can increase the likelihood of overwintering survival of controls and help ensure that LSCFSs are comparable. Our study demonstrates how a mechanistic model can be used to inform study designs for higher tier effects studies. Environ Toxicol Chem 2020;39:2286–2297. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Environmental Modelling and Software, Feb 1, 2021
The acceptance and usefulness of simulation models are often limited by the efficiency, transpare... more The acceptance and usefulness of simulation models are often limited by the efficiency, transparency, reproducibility, and reliability of the modelling process. We address these issues by suggesting that modellers (1) "trace" the iterative modelling process by keeping a modelling notebook corresponding to the laboratory notebooks used by empirical researchers, (2) use a standardized notebook structure and terminology based on the existing TRACE documentation framework, and (3) use their notebooks to compile TRACE documents that supplement publications and reports. These practices have benefits for model developers, users, and stakeholders: improved and efficient model design, analysis, testing, and application; increased model acceptance and reuse; and replicability and reproducibility of the model and the simulation experiments. Using TRACE terminology and structure in modelling notebooks facilitates production of TRACE documents. We explain the
The role of ecological models in linking ecological risk assessment to ecosystem services in agro... more The role of ecological models in linking ecological risk assessment to ecosystem services in agroecosystems
Environmental Modelling & Software, 2021
The acceptance and usefulness of simulation models are often limited by the efficiency, transpare... more The acceptance and usefulness of simulation models are often limited by the efficiency, transparency, reproducibility, and reliability of the modelling process. We address these issues by suggesting that modellers (1) "trace" the iterative modelling process by keeping a modelling notebook corresponding to the laboratory notebooks used by empirical researchers, (2) use a standardized notebook structure and terminology based on the existing TRACE documentation framework, and (3) use their notebooks to compile TRACE documents that supplement publications and reports. These practices have benefits for model developers, users, and stakeholders: improved and efficient model design, analysis, testing, and application; increased model acceptance and reuse; and replicability and reproducibility of the model and the simulation experiments. Using TRACE terminology and structure in modelling notebooks facilitates production of TRACE documents. We explain the
Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protec... more Aquatic mesocosms are complex test systems used within regulatory risk assessment of plant protection products. These model ecosystems allow to capture interactions of multiple species under environmental conditions. They enable assessment of direct and indirect effects of stressors at all trophic levels and impacts on ecosystem functions. Due to the limited ability to test the multitude of potential exposure scenarios, cross-linking aquatic mesocosm studies with virtual mesocosms, i.e. aquatic system models (ASMs), can serve to meet the demand for more environmental realism and ecological relevance in risk assessment. In this study, full control data sets from seven aquatic mesocosm studies conducted at a single test facility under GLP are graphically analysed. Thereby, not only a comprehensive data base but also an insight into the species present, their dynamics over time and variability in unchallenged mesocosms is provided. While consistency in dynamics could be discerned for p...
PLOS ONE, Jan 24, 2013
Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic i... more Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic insects. Dispersal is often the limiting factor for successful re-colonization and recovery of stressed habitats. Therefore, in this study, we evaluated the effects of landscape permeability, assuming a combination of riparian vegetation (edge permeability) and other vegetation (landscape matrix permeability), and distance between waterbodies on the colonization and recovery potential of weakly flying insects. For this purpose, we developed two models, a movement and a population model of the non-biting midge, Chironomus riparius, an aquatic insect with weak flying abilities. With the movement model we predicted the outcome of dispersal in a landscape with several linear water bodies (ditches) under different assumptions regarding landscapedependent movement. Output from the movement model constituted the probabilities of encountering another ditch and of staying in the natal ditch or perishing in the landscape matrix, and was used in the second model. With this individualbased model of midge populations, we assessed the implications for population persistence and for recovery potential after an extreme stress event. We showed that a combination of landscape attributes from the movement model determines the fate of dispersing individuals and, once extrapolated to the population level, has a big impact on the persistence and recovery of populations. Population persistence benefited from low edge permeability as it reduced the dispersal mortality which was the main factor determining population persistence and viability. However, population recovery benefited from higher edge permeability, but this was conditional on the low effective distance that ensured fewer losses in the landscape matrix. We discuss these findings with respect to possible landscape management scenarios.
Frontiers in Ecology and Evolution
IntroductionHabitat restoration aims at reinstating abiotic and biotic habitat conditions to supp... more IntroductionHabitat restoration aims at reinstating abiotic and biotic habitat conditions to support long-term species persistence and viability. This management practice is commonly part of recovery plans developed for species listed as threatened or endangered under the Endangered Species Act. The endangered Topeka shiner (Notropis topeka) inhabits off-channel habitats, such as oxbow lakes which are increasingly the focus of restoration, but the exact abiotic conditions conducive to its persistence in this habitat are not fully understood. In this study, a hybrid model consisting of an individual-based model of the Topeka shiner and an aquatic ecosystem model representing the oxbow habitat was applied to identify optimal environmental conditions for the persistence of Topeka shiner populations.Materials and methodsEnvironmental conditions that correlated with Topeka shiner presence were gathered from published studies and included water temperature, turbidity, oxbow depth, light i...
Environmental Toxicology and Chemistry
The occurrence of some species listed under the United States' Endangered Species Act in agri... more The occurrence of some species listed under the United States' Endangered Species Act in agricultural landscapes suggests that their habitats could potentially be exposed to pesticides. However, the potential effects from such exposures on populations are difficult to estimate. Mechanistic models can provide an avenue to estimating the potential impacts on populations, considering realistic assumptions about the ecology of the species, the ecosystem it is part of, and the potential exposures within the habitat. In the present study, we applied a hybrid model of the Topeka shiner (Notropis topeka), a small endangered cyprinid fish endemic to the US Midwest, to assess the potential population‐level effects of realistic exposures to a fungicide (benzovindiflupyr). The Topeka shiner populations were simulated in the context of the food web found in oxbow habitats that are the focus of ongoing habitat restoration efforts for the species. We applied realistic, time‐variable exposure scenarios and represented lethal and sublethal effects to individual Topeka shiners using toxicokinetic–toxicodynamic models. With fish in general showing the highest sensitivity to the compound, direct effects on simulated Topeka shiner populations governed the population‐level effects. We characterized the population‐level effects of different exposure scenarios with exposure multiplication factors (EMFs) applied. The introduction of a vegetative filter strip (VFS; 15 ft; 4.6 m) between the treated area and the oxbow habitat was shown to be effective as mitigation because EMFs were 2 to 3 times higher than for the exposure scenario without VFS. Environ Toxicol Chem 2021;40:2615–2628. © 2021 SETAC
Environmental Toxicology and Chemistry, 2020
In pesticide risk assessments, semifield studies, such as large‐scale colony feeding studies (LSC... more In pesticide risk assessments, semifield studies, such as large‐scale colony feeding studies (LSCFSs), are conducted to assess potential risks at the honey bee colony level. However, such studies are very cost and time intensive, and high overwintering losses of untreated control hives have been observed in some studies. Honey bee colony models such as BEEHAVE may provide tools to systematically assess multiple factors influencing colony outcomes, to inform study design, and to estimate pesticide impacts under varying environmental conditions. Before they can be used reliably, models should be validated to demonstrate they can appropriately reproduce patterns observed in the field. Despite the recognized need for validation, methodologies to be used in the context of applied ecological models are not agreed on. For the parameterization, calibration, and validation of BEEHAVE, we used control data from multiple LSCFSs. We conducted detailed visual and quantitative performance analyses as a demonstration of validation methodologies. The BEEHAVE outputs showed good agreement with apiary‐specific validation data sets representing the first year of the studies. However, the simulations of colony dynamics in the spring periods following overwintering were identified as less reliable. The comprehensive validation effort applied provides important insights that can inform the usability of BEEHAVE in applications related to higher tier risk assessments. In addition, the validation methodology applied could be used in a wider context of ecological models. Environ Toxicol Chem 2020;39:2269–2285. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Integrated Environmental Assessment and Management, 2019
Despite widespread acceptance of the utility of population modeling and advocacy of these approac... more Despite widespread acceptance of the utility of population modeling and advocacy of these approaches for a more ecologically relevant perspective, they are not routinely incorporated in ecological risk assessments (ERA). A systematic framework for situation-specific model development is one of the major challenges to broadly adopting population models in ERA. As risk assessors confront the multitude of species and chemicals requiring evaluation, an adaptable stepwise guide for model parameterization would facilitate this process. Additional guidance on interpretation of model output and evaluating uncertainty would further contribute to establishing consensus on good modeling practices. We build on previous work that created a framework and decision guide for developing population models for ERA by focusing on data types, model structure, and extrinsic stressors relevant to anuran amphibians. Anurans have a unique life cycle with varying habitat requirements and high phenotypic plasticity. These species belong to the amphibian class, which is facing global population decline due in large part to anthropogenic stressors, including chemicals. We synthesize information from databases and literature relevant to amphibian risks to identify traits that influence exposure likelihood, inherent sensitivity, population vulnerability, and environmental constraints. We link these concerns with relevant population modeling methods and structure in order to evaluate pesticide effects with appropriate scale and parameterization. A standardized population modeling approach, with additional guidance for anuran ERA, offers an example method for quantifying population risks and evaluating long-term impacts of chemical stressors to populations.
Environmental Toxicology and Chemistry, 2019
This work represents a collaboration among Cardno, Incorporated, Waterborne Environmental Incorpo... more This work represents a collaboration among Cardno, Incorporated, Waterborne Environmental Incorporated, and Syngenta Crop Protection, LLC. The project was sponsored by Syngenta Crop Protection, LLC. The authors are grateful for the comments and suggestions of two anonymous reviewers, who helped improve the manuscript.
Integrated Environmental Assessment and Management, 2021
The assimilation of population models into Ecological Risk Assessment (ERA) has been hindered by ... more The assimilation of population models into Ecological Risk Assessment (ERA) has been hindered by their range of complexity, uncertainty, resource investment, and data availability. Likewise, ensuring that the models address risk assessment objectives has been challenging. Recent research efforts have begun to tackle these challenges by creating an integrated Modeling Framework and Decision Guide to aid the development of population models with respect to ERA objectives and data availability. In the Framework, the trade-offs associated with the generality, realism, and precision of an assessment are used to guide the development of a population model commensurate with the protection goal. The Decision Guide provides risk assessors with a stepwise process to assist them in developing a conceptual model that is appropriate for the assessment objective and available data. We have merged the Decision Guide and Modeling Framework into a comprehensive approach (Pop-GUIDE, Population modeling Guidance, Use, Interpretation, and Development for Ecological risk assessment) for the development of population models for ERA that is applicable across regulatory statutes and assessment objectives. In Phase 1 of Pop-GUIDE, assessors are guided through the trade-offs of ERA generality, realism, and precision, which are translated into model objectives. In Phase 2, available data are assimilated and characterized as general, realistic, and/or precise. Phase 3 provides a series of dichotomous questions to guide development of a conceptual model that matches the complexity and uncertainty appropriate for the assessment that is in concordance with the available data. This phase guides model developers and users to ensure consistency and transparency of the modeling process. We introduce Pop-GUIDE as the most comprehensive guidance for population model development provided to date. It is the first of such documents that includes an evaluation of uncertainty as a function of the tolerance of the assessment in which its applied. We demonstrate *
Ecological Modelling, 2019
The Topeka shiner, a small cyprinid fish, is a seminal example of an endangered aquatic species i... more The Topeka shiner, a small cyprinid fish, is a seminal example of an endangered aquatic species in the Midwestern USA. Populations and their associated critical habitats may experience potential direct and/or indirect effects from anthropogenic activity. However, potential impacts on fish populations from alterations in the food web are difficult to predict because they are based on complex dynamics of food web interactions. In order to simulate Topeka shiner population dynamics under different food-web scenarios, a hybrid modeling approach was developed by linking an aquatic food web model (comprehensive aquatic systems model, CASM TS) with a species-specific, individual-based population model (TS-IBM). The CASM TS was parameterized and calibrated to represent the waterbody conditions and aquatic species community in a small headwater pool in Iowa, representative of key habitat for the Topeka shiner within its geographical range. In the TS-IBM, life history, growth, and diet are represented and based on data available from the literature for the Topeka shiner and/or surrogate species. The two models are linked by the transfer of daily biomasses of Topeka shiner diet items. We simulated the effects of alterations of the food web on the Topeka shiner populations by systematically reducing the available prey base biomass. Reductions in different food groups had varying impacts on the simulated Topeka shiner populations and were dependent on the species' preference for detritus consumption. Simulations also included predation and identified predator densities to which Topeka shiner populations were vulnerable. The hybrid model provides a platform for the assessment of potential direct and food-web mediated indirect effects of stressors for the purposes of risk assessment, habitat management, and species recovery plans.
Environmental Toxicology and Chemistry, 2019
Discerning potential effects of insecticides on honey bee colonies in field studies conducted und... more Discerning potential effects of insecticides on honey bee colonies in field studies conducted under realistic conditions can be challenging because of concurrent interactions with other environmental conditions. Honey bee colony models can control exposures and other environmental factors, as well as assess links among pollen and nectar residues in the landscape, their influx into the colony, and the resulting exposures and effects on bees at different developmental stages. We extended the colony model BEEHAVE to represent exposure to the insecticide clothianidin via residues in pollen from treated cornfields set in real agricultural landscapes in the US Midwest. We assessed their potential risks to honey bee colonies over a 1-yr cycle. Clothianidin effects on colony strength were only observed if unrealistically high residue levels in the pollen were simulated. The landscape composition significantly impacted the collection of pollen (residue exposure) from the cornfields, resulting in higher colony-level effects in landscapes with lower proportions of semi-natural land. The application of the extended BEEHAVE model with a pollen exposure-effects module provides a case study for the application of a mechanistic honey bee colony model in pesticide risk assessment integrating the impact of a range of landscape compositions.
Environmental toxicology and chemistry, 2018
Population models can facilitate assessment of potential impacts of pesticides on populations or ... more Population models can facilitate assessment of potential impacts of pesticides on populations or species rather than individuals and have been identified as important tools for pesticide risk assessment of nontarget species including those listed under the Endangered Species Act. Few examples of population models developed for this specific purpose are available; however, population models are commonly used in conservation science as a tool to project the viability of populations and the long-term outcomes of management actions. We present a population model for Mead's milkweed (Asclepias meadii), a species listed as threatened under the Endangered Species Act throughout its range across the Midwestern United States. We adapted a published population model based on demographic field data for application in pesticide risk assessment. Exposure and effects were modeled as reductions of sets of vital rates in the transition matrices, simulating both lethal and sublethal effects of h...
Environmental toxicology and chemistry / SETAC, Jan 6, 2016
Although population models are recognized as necessary tools in the ecological risk assessment of... more Although population models are recognized as necessary tools in the ecological risk assessment of pesticides, particularly for species listed under the Endangered Species Act, their application in this context is currently limited to very few cases. The authors developed a detailed individual-based population model for a threatened plant species, the decurrent false aster (Boltonia decurrens), for application in pesticide risk assessment. Floods and competition with other plant species are known factors that drive the species' population dynamics and were included in the model approach. The authors use the model to compare the population-level effects of five toxicity surrogates applied to B. decurrens under varying environmental conditions. The model results suggest that the environmental conditions under which herbicide applications occur may have a higher impact on populations than organism-level sensitivities to an herbicide within a realistic range. Indirect effects may be ...