Pop-guide: Population modeling guidance, use, interpretation, and development for ecological risk assessment

Abstract

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, Population modeling Guidance, Use, Interpretation, and Development for Ecological risk assessment (Pop-GUIDE), 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 and demonstrate its use through case studies using fish as an example taxon and the US Federal Insecticide Fungicide and Rodenticide Act and Endangered Species Act as example regulatory statutes. Integr Environ Assess Manag 2021;17:767-784. © 2020 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Keywords: Complexity; Ecological risk assessment; Guidance; Population modeling; Uncertainty.

Figure 1.

Process flow of Pop-GUIDE that involves defining model objective (Raimondo et al. 2018) (A), data compilation (B), decision steps to guide model complexity (C), and development of conceptual model and model implementation and evaluation (D).

Figure 2.

Decision tree to identify the category of trade-offs among generality, realism, and precision of an ERA based on its objectives. ERA = ecological risk assessment.

Figure 3.

Life history representation used for both delta smelt and fathead minnow case study. Life history of both fish is represented by a fish with iteroparous spawning, where survival rates are available for egg, larva, juvenile, and adult stages.

Figure 4.

Conceptual model for assessing the risks of chlorpyrifos exposure to delta smelt (A) and fathead minnow (B). The entirety of the modeling space is represented by the large grey box. Chemical exposure (orange box) and effects (green box) are overlapping compartments within the model. The white boxes are model components, and the arrows depict their connections. Red arrows depict adverse pathways of chlorpyrifos, and black arrows represent all other connections. The extent of overlap for various compartments is conceptual and not intended to be a scaled representation of proportional overlap of layers.

Figure 4.

Conceptual model for assessing the risks of chlorpyrifos exposure to delta smelt (A) and fathead minnow (B). The entirety of the modeling space is represented by the large grey box. Chemical exposure (orange box) and effects (green box) are overlapping compartments within the model. The white boxes are model components, and the arrows depict their connections. Red arrows depict adverse pathways of chlorpyrifos, and black arrows represent all other connections. The extent of overlap for various compartments is conceptual and not intended to be a scaled representation of proportional overlap of layers.