14 Aug 2026

Travel Times on Inland Waterways: Historic Statistical Calculations Between Selected Locks and River Confluences Using Automatic Identification System (AIS) Data from Calendar Year 2021

Abstract: In the context of multimodal-freight modeling efforts, the US Army Corps of Engineers (USACE), Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), entered into an inter-agency agreement with the Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS), to produce travel-time statistics for select portions of the US inland waterway transportation system. Statistics include the median, interquartile range average, and 10th–90th percentile averages between origin and destination (OD) sets selected based on vessel traffic activity, especially lock and dam locations, which are natural stopping points. Travel-time statistics are derived from position reports broadcast via Automatic Identification System (AIS) transceivers for vessel transits that occurred in 2021. This technical report summarizes the methodology and findings.

14 Aug 2026

A Local Meteoric Water Line for Interior Alaska Constrains Paleoclimate from 40 000 Year Old Relict Permafrost

Abstract: Anthropogenic climate warming is degrading permafrost across interior Alaska. Information from past warming events provides long-term perspectives for future trajectories; however, late Quaternary seasonal temperatures are poorly constrained. We have established a stable water isotope meteoric water line for interior Alaska and measured stable water isotope values from 126 permafrost cores representing different ice types deposited over the past ∼40 ka (thousand years before 1950 CE). Samples represent two late Quaternary warm periods: marine isotope stage three (MIS3; 57–29 ka) and the Holocene (11.7 ka-present). Older samples provide insight into local climatic conditions slightly before the first archeological evidence for Paleolithic hunter-gatherers in the region. From permafrost ice we calculate that summer temperatures warmed by ∼10 ◦C between late MIS3 and today, with six degrees of warming between 40–30 ka and 3 ka and an additional 4 ◦C of warming since 3 ka. Half this recent 4 ◦C warming has occurred over the past 70 years.

14 Aug 2026

A linguistic analysis of energy terminology in the wastewater literature

Abstract: Recent wastewater treatment research has focused on technologies that can recover resources such as energy from the influent waste stream. Many unrelated studies have introduced or used energy-related terms to describe changes to wastewater treatment plant energy balances based on these technological innovations. Unfortunately, these wastewater energy-related terms are not well defined in the literature, with many used interchangeably and/or inconsistently. To address this shortcoming, this study (1) identified and defined the most prominent energy-related terms in academic literature, (2) proposed a classification schema, and (3) explored trends in term usage over time. Energy-related terms identified from the literature were defined and classified based on the term’s functional role in the context of wastewater treatment plant energy use. Specifically, each term was classified as a wastewater treatment plant’s long-term energy ‘state’, a descriptive short-term energy ‘condition’ at the plant, or an energy ‘mechanism’ that drives a plant from one state to another. The trend analysis concluded that the development of energy-related wastewater literature has generally outpaced the baseline rate of academic publishing in all fields. The results of this study can ensure clear communication between actors in the wastewater treatment sector by standardizing definitions for energy-related terms.

14 Aug 2026

Revisiting Classical Biological Control of Hydrilla verticillata: Historical Perspective and New Opportunities

Abstract: The invasive aquatic plant Hydrilla verticillata continues to threaten freshwater systems in the USA. Management is complicated by presence of three genetically distinct subspecies, of which H. verticillata ssp. lithuanica is the most recent introduction in the northeastern USA. Classical biological control programs have focused primarily on subspecies in southern states, but effectiveness against the new lineage, in cooler regions, or in tidal river systems where infestations may occur is unknown. We review the history of hydrilla biological control in the USA through the lens of the recent introduction and discuss opportunities to address the challenge. We summarize the current distribution and relevant biological traits of hydrilla lineages that may influence their management. We re-assess four previously approved insect agents (Hydrellia pakistanae, H. balciunasi, Bagous affinis, and B. hydrillae), discussing their suitability in novel environmental conditions of the northeastern USA and compatibility with H. verticillata ssp. lithuanica. The leaf-mining fly H. pakistanae is a promising candidate for immediate re-evaluation due to its availability and potential tolerance for cooler climates. Furthermore, there is a longer-term opportunity to develop microbial pathogens and discover new arthropod agents through targeted exploration in the native range of H. v. ssp. lithuanica, aided by modern molecular techniques. We conclude by outlining key research priorities to build an integrated and adaptive research strategy tailored to the unique biological and ecological context of the H. v. ssp. lithuanica invasion, emphasizing the need for a renewed, lineage-focused approach to the biological control of hydrilla.

13 Aug 2026

Engineering Practice Guide for Oyster Reefs: A Natural Infrastructure Approach for Coastal Systems

Abstract: Well-designed oyster reefs enhance coastal resilience by attenuating wave energy, influencing sediment transport, and stabilizing shorelines. As ecosystem engineers, oysters create biogenic reef structures that provide habitat, improve water quality, and support estuarine productivity. When appropriately designed, they can also contribute to coastal storm risk management and navigation improvement objectives. Historically, oyster reefs were widespread features of many US estuaries and bays, playing important roles in shoreline stabilization and estuarine function. However, many reefs have been degraded or lost due to development, overharvesting, and environmental change. Constructed oyster reefs present a natural infrastructure approach that can support both ecological and physical processes that benefit society. While oyster reefs provide multiple benefits, application as natural infrastructure often involves tradeoffs related to cost, performance uncertainty, and long-term sustainability. Oyster reef design should evaluate these tradeoffs and clearly communicate associated risks and expected benefits. This publication is part of a series of technical reports produced by the US Army Corps of Engineers (USACE) Engineering With Nature® Program, offering engineering practice guidelines for designing natural infrastructure solutions for riverine and coastal systems. This guide supports interdisciplinary teams in applying engineering and ecological principles to develop oyster reef projects as natural infrastructure features.

12 Aug 2026

Toxicity of Per- and Polyfluoroalkyl Substances in Elutriates Prepared with Estuarine and Freshwater Sediments

Abstract: PFAS has a ubiquitous environmental occurrence, posing challenges to sediment management. To address data gaps concerning release of PFAS from sediment to the water column during dredged material aquatic placement or other sediment resuspension activity, we generated elutriates from PFAS-contaminated sediments. Sediments were obtained from both freshwater and estuarine environments, with a field-collected sediment representative of contaminated areas and a spiked sediment with concentrations exceeding levels frequently measured at contaminated sites. We then conducted acute toxicity tests of the elutriates with species standardly used in dredging evaluations: the sheepshead minnow (Cyprinodon variegatus), the fathead minnow (Pimephales promelas), the water flea (Ceriodaphnia dubia), and the Mysid shrimp (Americamysis bahia). PFAS partitioning to sediment and organic matter was observed to increase with carbon chain length. PFAS-induced mortality was not observed in any of the four test species, as measured concentrations of PFAS were below levels known to cause negative effects in these organisms. Though PFAS concentrations in the spiked sediment elutriates exceeded concentrations known to cause effects in the most sensitive aquatic species, PFAS levels in the more environmentally relevant field-collected sediment elutriates did not. Consequently, PFAS released from the sediment to the water column is not expected to cause toxicity to pelagic biota during aquatic placement of dredged material.

12 Aug 2026

Lifecycle Analyses of Subaerial Beach Nourishments with Concurrent Nearshore Placement of Dredged Sediment and the Role of Alongshore Transport

Abstract: Beach nourishment has a high cost but offers large economic benefits. Therefore, extending the nourishment lifespan using dredged sediment from navigation channels could have a significant economic impact. This numerical modeling study develops and compares two approaches incorporating nearshore sediment placements into an existing one-dimensional numerical modeling procedure to predict the lifespans of subaerial beach nourishment strategies. Both approaches build directly on the stochastic lifecycle simulation methodology and results used in the Coastal Texas Protection and Restoration Feasibility Study. Simulations for western Galveston Island were modified to include annually recurring nearshore nourishment. Cross-shore beach transects were forced with 50 years of tropical cyclones and nontropical storms in a cross-shore morphological evolution model, and rebuilt when the dune eroded to half of its initial height. One group of simulations applied this previously developed model forcing to cross-shore profiles that were updated with recurring nearshore nourishments. A second group of simulations included a simplified representation of sediment deposition from the along-shore transport gradient created by the nearshore nourishments. In both sets of simulations, a large sediment feature was incrementally constructed at depths between 2.5 and 6 m. Over 30 life cycles, the number of times the beach was rebuilt was tracked for each 50-year simulation. Comparing the number of predicted beach renourishments indicates that this particular nearshore nourishment strategy did not substantially impact the subaerial beach morphology unless alongshore transport gradients were also included. Simulations that did include this alongshore transport gradient predicted 23% longer lifespans. This work was not able to incorporate validation against measured data, but future testing of this approach should be pursued before widespread or high-impact application. Modeling results indicate that along-shore processes are an important part of quantifying the positive impacts of nearshore nourishment.

12 Aug 2026

Introduction of Three Cryptic Lineages of Invasive Crested Floating Heart (Nymphoides cristata) in the Southeastern United States

Abstract: Crested floating heart [Nymphoides cristata (Roxb.) Kuntze] is an invasive aquatic plant in the southeastern United States. For clonal plants like N. cristata, clonal diversity may influence response to control tactics and/or evolutionary potential. However, little is known about the diversity of introduced N. cristata. In this study, we used genotyping by sequencing to quantify N. cristata diversity in the southeastern United States and determine how that diversity is distributed across the invaded range. Our results show that at least three distinct genetic lineages of N. cristata are present in the southeastern United States. Geographic distribution of the lineages varied, with one widespread lineage identified across several states and others only found in a single water body. There is also evidence of extensive asexual reproduction, with invaded water bodies often host to a single genetic lineage. The genetic diversity reported in this study likely results from multiple introductions of N. cristata to the southeastern United States and should be considered by managers when assessing control tactics, such as screening for biocontrol agents or herbicide testing. The extent and distribution of genetic diversity should also be considered by researchers studying the potential for invasive spread of N. cristata within the United States or hybridization with native Nymphoides species.

11 Aug 2026

Adaptive Covariance Tapering for Large Datasets and Application to Spatial Interpolation of Storm Surge

Abstract: Covariance tapering is a popular approach for accommodating computational efficiency for the application of Gaussian process -based spatial interpolation for large datasets. This is accomplished by introducing sparsity in the GP covariance matrix, through the introduction of a compactly supported taper function. The support of the taper function around each spatial node is defined through the taper range variable. The latter is selected to achieve the desired degree of global sparsity in the covariance matrix, and defines the number of connected neighbors around each node. For problems with irregular nodal density, adaptive covariance tapering can be used to improve accuracy for the taper implementation. In this case, the taper ranges of the taper function have spatial variability, allowing uniform local sparsity to be achieved despite the data irregularities. The optimization of the taper ranges to accomplish this objective has a computational burden that is dependent on the size of the database, prohibiting its application to very large datasets. This paper formally considers the adoption of adaptive covariance tapers for such datasets. Though algorithmic developments are general, the problem is discussed for a specific application, the spatial interpolation of storm surge. For establishing computational efficiency in the optimization of the taper ranges we propose to utilize only a small subset of nodes, termed inducing points. An adaptive, iterative formulation is further developed to support the selection of the inducing points, shown to be critical for achieving the desired local sparsity for the remaining points. At each iteration, the taper range selection is performed using the current subset of inducing points, the achieved sparsity across all nodes is estimated, and then new inducing points are added within the sub-regions for which the discrepancy from the target local sparsity is the largest. The latter points are considered to have the highest expected utility as inducing points. Adding inducing points in close proximity is avoided through the inclusion of a clustering step. The implementation is demonstrated for interpolation of peak storm surge along the New Jersey coast, using two different domains, one with 64,379 nodes and one with 271,669 nodes.

11 Aug 2026

Eight Recommendations to Enhance Biodiversity Outcomes of Nature-Based Solutions at Multiple Scales

Abstract: Ambitions to mainstream Nature-based Solutions (NbS) and achieve global implementation are hampered by the lack of transdisciplinary integration across disciplines and practice. Ecological knowledge, including an under-standing of how biodiversity can support, and be supported by, NbS design and implementation remains an under-studied component of the NbS concept despite its critical importance. Starting with a brief primer on the major roles that biodiversity plays in NbS performance, we present eight recommendations for enhancing biodiversity in NbS planning and implementation. This narrative expert synthesis draws from an interdisciplinary literature search and decades of experience across landscape ecology, environmental engineering, urban planning, wildlife management, ecological restoration, and conservation science. Recommendations emphasize the importance of considering the ecological mechanisms that support biodiversity (i.e., viable populations of coexisting species) and understanding the role of organismal life history, species interactions, habitat preferences, and metapopulation dynamics in determining NbS features’ ecological resilience and contributions to biodiversity enhancement (i.e., IUCN Global Standard Criterion 3). We also emphasize the importance of assessing biodiversity across spatial scales and dimensions (e.g., functional, phylogenetic) and monitoring and ecological management for anticipating and adapting to unexpected outcomes, invasive species, and ecosystem dis-services. This review is intended to increase connections between ecological science, conservation biology, and NbS implementation to support more biodiverse projects with more robust, resilient, and multifunctional performance and greater contributions to global conservation.