26 Sep 2023

Microseira wollei (M. wollei) Blooms in Freshwater Ecosystems in Lake St. Clair (Michigan, USA)–Impacts and Possible Management Approaches

PURPOSE: The proliferation and shoreline accumulation of the filamentous biphasic cyanobacterium, Microseira wollei (M. wollei) (previously classified as Lyngbya wollei), have become an increasing problem in the Great Lakes, both for aesthetic reasons and its potential to harbor harmful bacteria and pathogens (Vijayavel et al. 2013). Occurrences have been reported and studies have also been conducted in the southeastern US where M. wollei has become a nuisance in recent years and is known to produce toxins (Hudon et al. 2014). Reports of M. wollei proliferations in the eastern US have been identified in the Manitoba lakes (Macbeth 2004), in Lake Erie from Maumee Bay (Bridgeman and Penamon 2010), in Lake St. Clair near Detroit (Vijayavel et al. 2013), and throughout the St Lawrence River (Vis et al. 2008; Lévesque et al. 2012). M. wollei has become a serious nuisance for marinas, public beaches, and lakefront property owners. In addition, M. wollei appears to have the ability to produce a wide range of toxins, but the conditions promoting their production, type, and concentration are poorly known (Hudon et al. 2014). Occurrences of large algal mats matching characteristics of M. wollei have been observed along the northwest shore and nearshore waters of the beach at Lake St. Clair dating back to 2010. To date, a comprehensive study detailing the potential impacts M. wollei has on freshwater ecosystems in the Great Lakes River, particularly Lake St. Clair is lacking. Further, management solutions are not well understood. This technical note (TN) reviews the potential causes of M. wollei blooms and their ecological impacts on aquatic systems and assesses the management options available to eliminate or minimize the impacts of these blooms.

26 Sep 2023

Linking the SEDLZJ Portable Standalone Library to the CMS Coastal Hydrodynamic Model

PURPOSE: This document describes the repackaging and linkage of the Sandia National Laboratories Environmental Fluid Dynamics Sediment Processes Code (SNL-EFDC-SEDZLJ), (Thanh et al. 2008). It was originally incorporated within a modified version of the US Environmental Protection Agency’s (USEPA) EFDC public-domain surface-water flow, sediment transport, and water-quality model developed by John Hamrick (Hamrick 1992) and its linkage to the ERDC-CHL-CMS hydrodynamic model. SNL-EFDC simulates flow and transport of sediment as bedload and suspended load. SNL-EFDC-SEDZLJ improves EFDC with updated sediment kinetics subroutines. Sediment erosion is calculated using data collected with a Sediment Erosion at Depth flume (SEDflume). SEDflume measures erosion rates as a function of shear stress and depth from relatively undisturbed cores taken directly from the sediment bed below the water body of interest. The use of SEDflume data provides more accurate sediment erosion rates that are directly input to the model.

26 Sep 2023

Isolation and Characterization of Bacterial Isolates from Alaskan Permafrost for Synthetic Biology Applications

Abstract: Operations in the Artic and other cold regions require technologies that can perform reliably under extreme cold conditions. Permafrost and frozen soils harbor a wide range of microorganisms that have adapted to extremely low temperatures and have unique metabolic capabilities relevant to military operations and that could be exploited to develop biotechnologies optimized for cold environments. Cold-tolerant bacteria (psychrophiles and psychrotrophs) are critical to the development of synthetic biology technologies meant to work in cold environments like the Arctic. Using bacteria isolated from Alaskan permafrost, we applied an experimental pipeline to test the best candidates for use as biological platforms, or chassis, for low-temperature synthetic biology. Since synthetic biology constructs will perform only as well as their chassis, it is critical that circuits expected to perform under extreme cold conditions are housed in chassis that are adapted to those conditions. We identified one permafrost isolate, PTI8, related to Rhodococcus fascians, that is capable of growing from −1°C to at least 25°C and which we experimentally confirmed to uptake and express the broad host range plasmid pBTK519, suggesting PTI8 is a candidate for use as a novel cold-adapted chassis for synthetic biology.

26 Sep 2023

Evaluation of a Visible Light Responsive Photocatalytic Coating to Resist Microbial Contamination and Increase Indoor Air Quality

Abstract: To meet new Department of Defense (DoD) energy standards, buildings are being constructed, and existing buildings are being retrofitted with tighter envelops. These new standards can reduce operational costs significantly but also limit fresh outdoor air coming into the built environments. This can result in the accumulation of harmful substances within buildings, which can have adverse effects on its occupants. New photocatalytic coatings may be a solution to this ever-increasing problem as they have the ability to destroy both chemical and biological toxins when activated with light. This work evaluated a novel indoor-light-reactive photocatalytic coating for its ability to eliminate or reduce microbial contamination under in situ test conditions. However, air and surface sampling revealed no reduction in either viable fungi and bacteria or total air-borne mold spores. Additionally, no significant differentiation could be made in the composition of volatile organics between the treated and untreated areas. However, testing the photocatalytic activity of the coating with standardized test methods and increased illumination, revealed the coating did exhibit antimicrobial activity against mold, bacteria, and viruses. This suggested that there may be limited benefit to using the indoor-light-reactive photocatalytic coating to inhibit microbial contamination unless specific lighting conditions can be met.

25 Sep 2023

Defining Levels of Effort for Ecological Models

BACKGROUND: While models are useful tools for decision-making in environmental management, the question arises about the level of effort required to develop an effective model for a given application. In some cases, it is unclear whether more analysis would lead to choosing a better course of action. This technical note (TN) examines the role of ecological model complexity in ecosystem management. First, model complexity is examined through the lens of risk informed planning. Second, a framework is presented for categorizing five different levels of effort that range from conceptual models to detailed predictive tools. This framework is proposed to enhance communication and provide consistency in ecological modeling applications. Third, the level of effort framework is applied to a set of models in the Middle Rio Grande River system to demonstrate the framework’s utility and application. Ultimately, this TN seeks to guide planners in determining an appropriate level of effort relative to risks associated with uncertainty and resource availability for a given application.

21 Sep 2023

Field Demonstration of a Peroxide-Based Algaecide for Harmful Algal Bloom Control in Lake Okeechobee

Abstract: Large-scale cyanobacterial harmful algal blooms (cHABs) in Lake Okeechobee, Florida, and connected waterways routinely impair water resources. This study conducted a field demonstration of a peroxide-based algaecide in 2020 in the Pahokee Marina on Lake Okeechobee to evaluate the algaecide’s suitability for near-future operational implementation. Within minutes of treatment, rapid oxidation of cHAB cells occurred in the form of bleaching and cell lysis. On average, levels in the treatment area decreased by 4 hours after treatment (HAT) and remained low out to 24 HAT: chlorophyll decreased 87%, phycocyanin decreased 85%, total microcystin levels decreased from 50 μg L⁻¹ to 4 μg L⁻¹ at 4 HAT and then increased to 11 μg L⁻¹ by 24 HAT, hydrogen peroxide concentrations averaged 6.1 mg L⁻¹ 0.5 HAT and then dropped below detection limits by 24 HAT, and Microcystis spp. cell densities decreased at 4 HAT in all but four sampling sites. However, inflows of cHAB-infested lake water in some portions of the treatment area resulted in lack of control at these sites. Because of their vulnerability to influxes of cHABs from surrounding nontreated waters via water-exchange processes driven by wind-induced surface currents, future applications must therefore consider treatment area size.

20 Sep 2023

Mapping and Localization Within a Mock Sewer System

Abstract: Herein, we explored a robot’s ability to localize and map, both in simulation and on a physical robot, within a mock sewer system. Mapping and localization techniques were first developed and tested in simulation and were then transitioned to the actual robot for additional physical testing. Several odometry and simultaneous localization and mapping (SLAM) techniques, including gmapping, SLAM toolbox, elevation mapping, and RTABMap, were evaluated for this particular environment. The results of the odometry and the various SLAM approaches are discussed in detail.

18 Sep 2023

A Resilient Path Forward for the Marine Transportation System: Recommendations for Response and Recovery Operations from the 2017-2019 Hurricane Seasons

Abstract: The Marine Transportation System (MTS), Resilience Integrated Action Team (RIAT), is tasked by the coordinating board of the US Committee on the MTS to serve as a coordinating body to identify the impacts, best practices, and lessons learned by federal agencies involved in the response and recovery of the MTS after hurricane seasons. In response to this request, the RIAT has focused its analysis on the ability of MTS federal agencies to prepare, respond, recover, and adapt to as well as from disruptions. This was accomplished through workshops focused on gathering the collective experiences of emergency response professionals. In 2017, recommendations were gathered based on experiences responding to Hurricanes Harvey, Irma, and Maria. In this report, a similar approach was adopted to gather findings from Hurricanes Florence and Michael in 2018 and Hurricane Dorian in 2019. Utilizing the successes, challenges, and best practices from all six of these storms, the RIAT identified key coordinating bodies and the participants for each and key takeaways relative to the coordination of agencies with respect to the four steps of resilience: prepare, absorb, recover, and adapt.

18 Sep 2023

Accelerated Corrosion of Infrastructural Seven-Strand Cables via Additively Manufactured Corrosion Flow Cells

Purpose: The purpose of this project was to generate an accelerated corrosion methodology capable of producing seven-strand cables with simulated corrosive defects for calibration of nondestructive analysis (NDA) techniques. An additively manufactured accelerated corrosion cell was motivated and designed. Previous attempts at accelerated electrochemical corrosion used a large cable area with a current density that was too low (i.e., 1 A/m²)* to effectuate efficient corrosion. The accelerated corrosion cell presented here takes advantage of the restricted area within the corrosion flow cell to maximize the corrosion rate in a consistent and calibrated manner (i.e., 2,000 A/m²).

15 Sep 2023

ERDC: A Tradition of Innovation

Abstract: As the U.S. Army Engineer Research and Development Center (ERDC) celebrates its 25th anniversary, “A Tradition of Innovation” traces the organization’s history from its precarious roots through its evolution into a world-class organization solving the toughest problems facing the nation and the Warfighter. This book highlights the key inflection points that shaped ERDC–from responding to national crises like 9/11 and Hurricane Katrina to changing climates, evolving military strategies and demands for greater computational power. As ERDC prepares to solve a myriad of new and escalating challenges, its engineers and scientists will build upon its tradition of innovation and lean into the cross-disciplinary culture forged during the organizations’ first quarter century.