AUGUST 2021
Understanding the Complex Dynamics of Endangered Species and Pesticide Exposure Through Population Modeling
Some species listed under the Endangered Species Act (ESA) occur in agricultural landscapes where their habitats have the potential to be exposed to pesticides. Aquatic species, in particular, may be at risk to pesticides applied to nearby agricultural fields, even though applications are not made directly to the aquatic habitat. Population modeling has emerged as a useful tool in predicting exposure risk and the impacts pesticides have on their populations.

A recent article we published in the Journal of Environmental Toxicology and Chemistry,
takes an in-depth look at how a hybrid model—combining an aquatic ecosystem model (CASM) and a species-specific population model for the Topeka shiner (TS-IBM)—can be used to estimate the potential impacts on populations. Through these models, we are able to consider realistic assumptions about the species ecology, ecosystem factors, and potential exposures within the habitat. Additionally, Toxicokinetic/Toxicodynamic (TKTD) models were incorporated into the TS-IBM to capture direct lethal and sublethal effects on individual fish from the time-variable exposures.

In this endangered Topeka shiner (Notropis topeka) study, a hybrid model was applied to compare the effects from potential exposure to a fungicide in oxbow habitats on the shiner population. Hybrid modeling approaches that combine species-specific models with an ecosystem-level model can be advantageous as this type of hybrid model sets population dynamics in the context of species interaction which can further address indirect effects mediated by the food web. We chose the example pesticide due to its known toxicity...
Aquatic Systems Models: a Virtual Mesocosm Could be a Regulatory Tool of the Future
Aquatic mesocosm studies have long been considered a higher-tier tool for informing risk assessments under European regulations. These simulated pond studies are designed to investigate the impact of a pesticide on an aquatic ecosystem and use the complexities of multiple trophic levels and long-term study duration to observe patterns of impact and recovery.

As presented at this year’s SETAC EU, Waterborne is currently coordinating and providing technical expertise in a collaboration mesocosm project funded by Syngenta, along with Cardno, Inc., EBP and EAWAG, gaiac, Integral Consulting, Inc., and Mesocosm GmbH. The project’s goal is to demonstrate how realistic representations of the food webs and environmental conditions in mesocosms will open the door to running virtual mesocosms... >>Read the full article
Pop-Guide: Providing Risk Assessors With a Critical Population Modeling Tool
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... >>Read the full article
Case Study: Application of an Ecological Model (BEEHAVE) to Large-Scale Honey Bee Colony Feeding Studies
In our June newsletter, we mentioned the recent release of a 2-part publication series in Environmental Toxicology and Chemistry presenting 1) a model validation of BEEHAVE and 2) an application of BEEHAVE. This month, we’re taking a deeper dive into these two publications and, through a case study, will show both how the BEEHAVE model can potentially be used for large-scale colony feeding studies (LSCFSs) and how it could inform future study designs in order to improve overwintering success in control hives as well as guide consistency across studies.

Part 1 of this series presents the validation of the BEEHAVE model with control data from large-scale colony feeding studies (LSCFSs). LSCFSs are studies used to assess the potential risks of pesticide exposure at the colony level and are typically conducted in higher-tier honey bee risk assessments. These studies are very costly and time-intensive and carry significant resource concerns should unexpected issues arise. They also carry challenges such as potential high overwintering losses in untreated controls (observed in some studies). In addition, study designs can vary with respect to... >>Read the rest of the article
Recent News: Check Out Our Newest Publication!
In our newest publication, accepted and published on the Environmental Toxicology and Chemistry website, we assess vulnerabilities to pesticide exposures across multiple bee species. This analysis highlights several uncertainties in the use of the Western honey bee as a surrogate species for pesticide risk assessment based on various bee traits and ecologies.
Waterborne Environmental is a renowned consulting firm that has provided innovative solutions to the world’s most complex environmental problems since 1993. Our experienced, unbiased scientists and engineers work across industries to evaluate environmental, ecological, and human risks. Our work spans across industry and regulatory agencies to support the balance in the needs of a growing population with the environmental impact on our valuable natural resources.

Our The Current Newsletter is published monthly. Visit us online to find more articles, videos, and information about our work. Click here to contact us.
Waterborne Environmental Inc.
CORPORATE HEADQUARTERS
897B Harrison Street SE
Leesburg, VA 20175
Phone: +1 (703) 777-0005
Connect with us