17 Jul 2025

Regulatory Considerations in the Development and Implementation of Biological Control for Invasive Mussels and Other Nontraditional Targets in the United States

Abstract: Ongoing research within the Department of the Interior, Bureau of Reclamation, the Department of Defense, and the US Army Corps of Engineers (USACE), in partnership with Molloy & Associates, aims to discover and develop biological controls to mitigate the negative effects of non-native dreissenid mussels on natural and human-made environments in the US. Although biological control technologies have been employed for decades to manage arthropod and plant pests, the workflow required to successfully develop and permit an agent for invasive bivalves has been unclear. Since 2020, the US Army Engineer Research and Development Center (ERDC) has been collaborating with the project team to compile the information needed to permit biological control agents for Dreissena spp. (i.e., zebra and quagga mussels) in the US. Permitting should cover (1) collection in the native or source country and export to the US, (2) importation (nonrelease) into the US, and (3) field (environmental) release of agents. Because Dreissena are nontraditional targets for biological control, the regulatory issues surrounding their management will differ from other common targets, such as invasive plants and arthropods. This document provides background information on biological control, describes how this project is different from most programs implemented in the US, speculates on what invasive mussel biological controls might be, and provides a road map for successful permitting of Dreissena biological controls. Additionally, other nontraditional, but good, targets for biological control may exist and have been overlooked. These other opportunities are briefly discussed. This report is the result of conversations between the project team and federal regulators, and it represents the best possible information needed to permit agents for invasive mussels in the US.

14 Jul 2025

Submerged Aquatic Vegetation Monitoring for Process-Based Model Development

Purpose: Submerged aquatic vegetation (SAV) habitat conservation and restoration are necessary actions to counteract the loss of these critical habitats and their associated ecosystem services, such as habitat provisioning and water quality improvements. Process-based numerical models are essential for planning effective and enduring SAV management strategies but require robust datasets to realistically represent processes at high spatial and temporal resolutions. This technical note (TN), developed by the US Army Engineer Research and Development Center–Environmental Laboratory (ERDC-EL), describes an SAV data collection framework that is being applied at freshwater pond mesocosms to better capture intra-annual SAV growth and mortality processes needed to parameterize process-based models.

11 Jul 2025

Lower Mississippi River Resource Assessment: Library of Aquatic Habitat Models

Abstract: Six ecosystem models were developed to evaluate restoration measures for the Lower Mississippi River Resource Assessment that considered connectivity between river and floodplain, substrate quality in riverine habitats, and targeted species of special interest including Paddlefish and wetland fish assemblages. A total of 85 restoration measures in the Hatchie to Loosahatchie reach were identified by the Project Delivery Team that had different modeling requirements. Field data collected by the Engineer Research and Development Center–Environmental Laboratory in the Lower Mississippi River and floodplain identified ecological guilds of fish and aquatic invertebrates representative of different fluvial habitats. Regression and frequency bar chart models developed from this database predicts a biotic response as a function of habitat quality. Six models applicable to either riverine (unidirectional flow) or floodplain (bidirectional flow) environments were used to evaluate measures for enhancing benthic substrates, reestablishing woody debris, and formation of eddies to diversify habitat. Outputs were normalized as a Habitat Suitability Index on a 0–1 scale and a spreadsheet developed to calculate and annualize Habitat Units for selected restoration measures. Models were certified by US Army Corps of Engineers National Ecosystem Restoration Planning Center of Expertise for regional use in the Lower Mississippi River.

25 Jun 2025

Bioconcentration, Maternal Transfer, and Toxicokinetics of PFOS in a Multi-Generational Zebrafish Exposure

Abstract: To enable risk characterization of perfluorooctane sulfonic acid in extended chronic and multi-generational exposures, we assessed PFOS bioconcentration in zebrafish exposed continuously to environmentally-relevant PFOS concentrations through 180 days postfertilization in parental and first filial generation fish. Exposures included five replicate tanks per treatment where whole-body PFOS concentrations were measured. Perfluorooctane sulfonic acid accumulation reached an apparent steady state at ≤ 14 dpf where whole-body wet-weight concentrations remained constant through 180 dpf in the P and F1 generations. The median bioconcentration factor of 934 L/kg was observed for all PFOS exposures with a range from 255 to 2,136 L/kg which varied with PFOS exposure concentration and sex of adult fish. Maternal transfer of PFOS was observed from P females to F1 eggs where maternal whole-body and egg PFOS burdens were equivalent, suggesting PFOS transfer to eggs was not a depuration pathway. Finally, a toxicokinetic model was developed that reliably reproduced PFOS whole-body burdens across all exposure durations spanning the P and F1 generations, providing a tool for PFOS bioaccumulation predictions relevant for risk assessment of acute, chronic, and multi-generational exposures.

24 Jun 2025

A Field Sampling and Analysis Protocol for Assessing Occupational Exposure and Risk from Military Munition Storage Magazines

Abstract: An occupational health study was conducted inside reinforced-concrete earth-covered munitions storage magazines at Fort Wingate Depot Activity. HEPA vacuuming of bulk dust and wipe sample verification post-vacuuming was used. In Phase 1, no explosives detections exceeded site-specific screening criteria. In Phase 2, no exceedances were noted for detected explosives with criterion. Using structure/ reactivity characteristics within the explosives category, surrogates were assigned to the six explosives without occupational health screening criteria. Based upon structural similarities within the analysis category, assignments of surrogates to explosives without criteria did not adversely impact the conclusions. In Phase 1, lead was detected in bulk dust in all igloos, and all exceeded the applicable criterion for commercial/industrial workers. In Phase 2, all lead detections in wipe samples were below the wipe screening criteria. Results indicated the ECM interiors posed no unacceptable dermal occupational risk for explosives or lead residues following bulk dust removal. HEPA filter vacuuming of interior bulk dust in ECMs at FWDA reduced occupational risk/hazard for exposure via inhalation and dermal contact under worst-case exposure conditions. Both phases of sampling are widely applicable, provided the site-specific assumptions made for this study are evaluated for suitability to another specific application and adjusted if needed.

17 Jun 2025

Evaluating Permanganate Oxidizable Carbon (POXC)’s Potential for Differentiating Carbon Pools in Wetland Soils

Abstract: Soil carbon (C) storage is a globally important ecosystem service with potential to contribute to climate change mitigation. Wetlands are heavily researched for this. Most studies focus on total C quantification; there is limited methods that evaluate differences in C stability and vulnerability to mineralization within the C pool. Permanganate oxidizable C (POXC) is a well-established soil health indicator shown to be sensitive to changing conditions or management regimes and may prove equally informative. This research quantified POXC in six diverse wetland soils, then evaluated the relationship between POXC and basic soil C properties, microbial indicators, and physical and chemical fractionation metrics. POXC averaged ~ 37 times greater in wetlands than upland agricultural soils, but was less robust in differentiating between individual wetlands than total C or organic matter content. Rather, the ratio of POXC to soil organic C may be a more informative metric for evaluating the proportion of slightly processed C in wetland soils. Significant correlations were found between POXC and almost all soil properties measured, suggesting POXC could be a rapid, reliable, and economical proxy for other analyses. Overall, POXC shows potential for providing novel information about wetland soil C stability, but requires additional research.

16 Jun 2025

Entropy-Based Guidance of Deep Neural Networks for Accelerated Convergence and Improved Performance

Abstract: Neural networks have dramatically increased our capacity to learn from large, high-dimensional datasets across innumerable disciplines. However, their decisions are not easily interpretable, their computational costs are high, and building and training them are not straightforward processes. To add structure to these efforts, we derive new mathematical results to efficiently measure the changes in entropy as fully-connected and convolutional neural networks process data. By measuring the change in entropy as networks process data effectively, patterns critical to a well-performing network can be visualized and identified. Entropy-based loss terms are developed to improve dense and convolutional model accuracy and efficiency by promoting the ideal entropy patterns. Experiments in image compression, image classification, and image segmentation on benchmark datasets demonstrate these losses guide neural networks to learn rich latent data representations in fewer dimensions, converge in fewer training epochs, and achieve higher accuracy.

16 Jun 2025

Development of Innovative Cyanophage-Based Biotechnology for Harmful Cyanobacterial Blooms Mitigation: Interim Progress Report

Abstract: Freshwater harmful cyanobacteria blooms (HCBs) are caused by toxin-producing cyanobacteria. Current efforts to prevent and mitigate HCBs include physical and chemical treatments, as well as manipulating the nutrient input and biological ecosystem of impacted water bodies. However, the development of remediation technologies lags behind the increasing frequency, prevalence, and severity of HCBs and their associated adverse health effects and socioeconomic losses. It is difficult to control the side effects of these remediation technologies due to their interactions with nontarget species, including microbes, plants, and animals. This project proposed the use of cyanophages, an abundant natural resource, to control HCBs in a target-specific manner. Here, the results of Year 1 of this effort are reported. Environmental field samples were collected, processed, and characterized morphologically and molecularly. Assays were refined for isolating and characterizing lytic environmental cyanophages. Cryopreservation methods were tested on pure cyanobacteria cultures, while well-characterized cyanophages were used to verify methods to retain infectivity for over 1 year. Methods to induce lysogenic phages to enter their lytic cycle were also explored. The goal was to develop a novel cyanophage-based biotechnology for HCBs mitigation by turning field-collected cyanophages into genetically modified (GM) or non-GM biocontrol agents to disrupt HCBs.

11 Jun 2025

A Bellwether for Microplastic in Wetland Catchments in the Great Lakes Region

Abstract: This study is intended as a bellwether for the occurrence of microplastics (MPs) in Great Lakes wetlands. In 2020, sediment, surface water, and atmospheric deposition samples were collected from wetland catchments in or near five National Wildlife Refuges (NWRs) in the Great Lakes region: Horicon-WI, Seney-MI, Shiawassee-MI, Ottawa- OH, and Montezuma-NY. Sediment and surface water samples were taken from river, stream, and canal inflows and outflows to and from wetland areas. Atmospheric deposition samples were collected in carboys placed near established rain gauges. These sample sites were chosen as indicators of MP deposition into and out of the region’s wetland systems. MPs were extracted from each sample, enumerated, and categorized by particle morphology and polymer type. Average MP particle abundances in the sediment and surface water samples ranged from 344 to 538 particles kg⁻¹ (dry weight) and 2–68 particles m⁻³, respectively. Atmospheric MP deposition ranged from 5.8 to 22.6 particles m⁻² d⁻¹. Fibers were the most abundant MP particle type found in each sample type (sediment, surface water, and atmospheric deposition), followed by fragments. These results suggest that input and retention of MPs are pervasive in the Great Lakes region and surrounding wetland areas.

10 Jun 2025

Developing an Inventory of US Army Corps of Engineers’ Nature-Based Infrastructure Projects

Abstract: The purpose of this report is to recommend a framework for developing a comprehensive database of US Army Corps of Engineers’ (USACE) natural infrastructure (NI) projects. Natural infrastructure is defined as an area or system that is naturally occurring, naturalized, or constructed to mimic naturally occurring features and then intentionally managed to enhance ecosystem value and provide social and economic benefits. Examples include river floodplains, setback levees, forested water supply watersheds, freshwater and coastal wetlands, living shorelines, dune and beach systems, living breakwaters, and reefs. NI is dynamic, with landscape-level interactions occurring among different features as well as in tandem with conventional infrastructure. Specifically, we identify the Engineering With Nature (EWN) ProMap database is identified as an attractive candidate for expansion. We also develop a tool for collecting project data that will improve data quality by standardizing information across projects, adopting an ecosystem services approach to cataloging project benefits, and incorporating social benefits metrics.