Population models provide a means for relating individual-level responses to a stressor to changes in population abundance and structure. The models’ value is in their ability to reduce uncertainty in the extrapolation of organism-level ecotoxicological observations and endpoints to ecologically relevant effects. However, there are many challenges incorporating population models into the ecological risk assessment process.

But first, what makes population models so useful? In a nutshell: population-level ecological effects can be extrapolated without the need for costly field studies with high numbers of test organisms and challenges due to novel study designs. Applying a population model allows for many different scenarios to be observed, beyond what is feasible to test through experiments with test organisms alone. What about the challenges? To begin with, modeling must be focused to address specific risk assessment objectives. Once a focus has been identified, scientists then must contend with the data availability, complexity, uncertainty of the model and the resources needed for its development.

To address these challenges, Waterborne’s team collaborated with population modelers across industry, academia, and the US EPA to develop a tool: Pop-GUIDE. Pop-GUIDE (Population modeling Guidance, Use, Interpretation, and Development for Ecological risk Assessment) serves as a stepwise decision guide and modeling framework. This tool has been designed to guide risk assessors and modelers through the following five phases to develop a conceptual model in line with the level of complexity and uncertainty appropriate for the available data and risk assessment goals:

Phase I. Model Objectives

Phase II. Data Compilation

Phase III. Decision Steps

Phase IV. Conceptual Model

Phase V. Model Implementation and Evaluation

We are excited to introduce Pop-GUIDE as the most comprehensive guidance for population model development to date! This guidance now allows us to overcome some of the challenges of assimilating population modeling into regulatory decision-making and will truly bring us into the future of ecological risk assessment! Our recent publication provides a deeper dive into the structure and layout of the guidance as well as case studies under multiple regulatory statutes.