Search Results (221)

Anthropogenic particles (APs), including suspected microplastics, are increasingly reported in freshwater ecosystems; however, baseline data remain limited for culturally important freshwater fish in the Mississippi River Headwaters. This study assessed the occurrence and morphology of APs in Ogaa (walleye; Sander vitreus) and Asaawe (yellow perch; Perca flavescens) collected from five northern Minnesota lakes. Gastrointestinal tract, liver, and fillet tissues from 49 fish were processed using a modified hydrogen peroxide digestion protocol and examined by stereomicroscopy. Because polymer confirmation was not conducted, visually identified particles are conservatively reported as anthropogenic particles rather than confirmed microplastics. Forty-one APs were identified across all tissues, with 43% of fish containing at least one particle ($0.83\pm 1.$ particles per fish). Fibers were the predominant morphology, followed by fragments, and walleye exhibited greater AP prevalence and abundance than yellow perch. Although descriptive differences were observed among lakes and tissues, statistical analyses did not detect significant relationships among the variables examined. These findings establish baseline information on AP occurrence in culturally important freshwater fish from the Mississippi River Headwaters and provide a foundation for future investigations incorporating polymer confirmation and expanded spatial and temporal sampling. Full article

In agricultural landscapes, alterations in river flow and channel geometry, increased sediment and nutrient loads, and invasive species degrade lotic ecosystems and are now being exacerbated by climate change. Stream restoration efforts respond to these pressures, but important questions remain about restoration impacts in landscapes undergoing rapid hydrologic change. Examining the relationship of stream restoration and flooding to channel geomorphology and greenhouse gas (CO₂, CH₄) diffusive fluxes on restored and reference reaches, we hypothesized that flood flows through restored reaches would increase cross-sectional area and floodplain connectivity while decreasing soft sediment depth, and they would increase CO₂ and CH₄ diffusive fluxes change in response to restoration-driven changes in channel form, floodplain reconnection, and floods. Through elevation profiles, geomorphic surveys, and greenhouse gas sampling, we compared channel form and CO₂ and CH₄ fluxes in a reach before and after restoration to four unrestored reference reaches in two streams in Wisconsin’s Driftless Area over a period that included multiple floods. Restoration activities were constrained by flood events and did little to enhance potential floodplain reconnection, yet they were related to increased emissions of CO₂ and CH₄ despite limited changes in channel form; meanwhile, flooding was related to short-term increases in emissions. These results highlight that legacies of agricultural practices are continuing to impact stream systems in subtle and compounding ways, despite and maybe even because of restoration interventions. Full article

The Mississippi River Delta region is of national and international relevance in terms of agriculture, energy, river navigation, and fisheries. Being one of the most engineered rivers in the world, the Mississippi River has been intensively altered over the past 150 years. The river alterations included the construction of dams, levees, diversions, channelization, spillway flood control systems, and many others. These engineering practices have significantly modified the natural hydrology and sediment dynamics of the river and its deltaic region. While these interventions have provided critical benefits such as flood protection, improved navigation, and economic development, they have also led to profound environmental and ecological consequences. The reduction in sediment delivery to the Mississippi River Delta has accelerated land loss, contributing to the disappearance of coastal wetlands at an alarming rate. The land loss has diminished critical habitats for wildlife, reduced storm surge protection for coastal communities, and disrupted the delta’s natural ability to adapt to fast subsidence. The long-term sustainability of the delta is further threatened by the compounding effects of climate change, including rising sea levels, increased storm intensity, and extreme precipitation and drought conditions. This paper examines the effects, consequences, and future risks of the major river engineering practices on the Mississippi River Delta and provides strategic recommendations that balance human needs with changing natural conditions to ensure sustainability. Specific recommendations include river diversion upstream of New Orleans, better strategies to deal with floods and droughts, strategic maintenance or removal of portions of levees, hybrid coastal-inland human migration, improved transportation connections between coast and inland, and better preparation for future ecosystem shifts. This review is needed because river engineering has made the Mississippi River Delta economically vital yet increasingly vulnerable to sediment loss, wetland collapse, saltwater intrusion, flooding, and population decline. By synthesizing these linked natural and human consequences, it provides a timely framework for rethinking delta sustainability under climate change. Full article

We present a 42-year (1984–2025) Landsat consistent satellite vegetation trajectory for coastal wetlands in the Shell Beach area in the Breton Sound estuary, Louisiana. We applied the Controlled Interrupted Time Series (CITS) analysis to the satellite record to quantify the causal effect of the 2009 Mississippi River Gulf Outlet (MRGO) closure on the coastal wetland vegetation. The analysis used NDVI, kNDVI, and NDII across 88 vegetation transect plots located within five Coastal Reference and Monitoring Systems (CRMS) stations in the Shell Beach wetlands. Vegetation communities identified included Saline, Brackish, Freshwater, and Intermediate marsh. Sentinel-2 data from 2015 to 2025 were retained as an independent parallel record for NDRE analysis only. Quarterly median composites were decomposed using the Seasonal-Trend decomposition using LOESS (STL) to isolate de-seasonalized vegetation anomalies. The CITS design used segmented Ordinary Least Squares (OLS) regression with Newey–West HAC standard errors (lag = 3) at the study area. Northern Barataria Bay was used as an untreated regional control site to remove concurrent climate and sea level rise confounders. Whilst Hurricane Katrina and subsequent years (2005–2008) were excluded from the models, the single group ITS identified significant negative post-closure slope change across three indices. These were NDVI (β3 = −0.0034 yr⁻¹, p = 0.000), NDII (β3 = −0.0032 yr⁻¹), and kNDVI (β3 = −0.0016 yr⁻¹). These values indicated continued site-level decline relative to the pre-closure trend. Community-stratified ITS analysis showed a distinct divergent pattern with Freshwater marshes demonstrating significant recovery, with NDVI β3 = +0.0190 yr⁻¹, p = 0.000, whilst Saline, Brackish, and Intermediate communities continued to decline. CITS Difference-in-Differences (DiD) confirmed that site-level NDII and kNDVI declines were MRGO-specific. The DiD findings were that NDII = −0.00313 yr⁻¹, p < 0.001; kNDVI = −0.00123 yr⁻¹, p = 0.008. These findings isolated that physiological water stress and the non-linear biomass losses were a result of the MRGO-closure. The Freshwater DiD for NDVI (+0.02071 yr⁻¹, p = 0.000) was the strongest evidence of MRGO-specific recovery. Barataria Freshwater declined, whilst the Shell Beach Freshwater recovered. The results demonstrated that multi-index decadal Landsat monitoring with seasonal decomposition and full inter-sensor harmonization is essential for restoration trajectory assessment in managed coastal wetlands. Full article

The 2019 Mississippi River floods were among the most severe in recent U.S. history, impacting 11 states and driven by multiple tributary flood events rather than a single episode. This study focuses on the Lower Mississippi River Basin in Mississippi, examining how flood frequency interacts with land ownership patterns to influence agricultural losses in the Yazoo–Mississippi Delta. Using Sentinel-2 imagery within Google Earth Engine, land use and land cover were classified with a random forest algorithm, followed by change detection and a flood recurrence–persistence modeling framework to map and characterize inundation. Results indicate that mid-year floods (April–July) caused the greatest crop losses, particularly in soybeans (4475 ha), cotton (501 ha), and corn (546 ha). Most impacts were associated with short-duration, low-recurrence floods, which affected many structures (1812) and extensive agricultural areas due to their broad spatial reach. Small agricultural parcels (≤48 ha) experienced the highest proportional exposure across flood zones, while medium and large parcels showed comparatively lower vulnerability. These findings highlight the importance of targeted resilience and mitigation strategies that account for flood frequency, land use, and land ownership patterns across the Delta. Full article

Sentiment expressions related to child maltreatment (CM) in public discourse are influenced by demographic, economic, and cultural factors and individual characteristics. Using 188,429 geotagged CM-related tweets during 2018–2022, we explored public sentiment expression about CM across the contiguous U.S. We applied multiscale geographically weighted regression (MGWR) to examine how contextual factors relate to the percentage of CM-related tweets with negative sentiment at the county level, revealing the spatial heterogeneity and varying geographic scales of these associations. Counties with higher male-to-female ratios and lower education levels tended to express negative sentiment in CM-related tweets, with consistent patterns observed nationwide. Five factors exhibited spatially varying associations by U.S. region, with higher levels of negative sentiment in the following contexts: a lower percentage of residents living in group quarters or a higher percentage of same-sex couples (Eastern and Central); fewer households lacking broadband access (Central); a higher percentage of single-parent households (New England and Southern Mississippi River); and areas where professionals are mandated to report CM (Great Lakes and Southern Appalachian Mountains). This study provides critical insights for policymakers to adjust policies, educators to design focused interventions, and the public to raise CM awareness. The methodology also provides a valuable framework for investigating public discourse on other social issues. Full article

The once-extensive coastal forested wetlands (CFWs) of the Mississippi River Delta (MRD) are declining under the combined pressures of pervasive hydrologic change, unregulated harvesting, relative water level rise (due to the combination of geological subsidence and sea-level rise—SLR), and climate change. We synthesize here over 50 years of research conducted in the MRD to examine the history of the CFWs and their management, their ecosystem functions and services, and the nature, extent, and severity of ongoing changes. Seedling recruitment failure and increasing salinity levels are the most immediate threats to forest persistence, necessitating management that restores hydrologic function and sediment and nutrient supply to allow seedling survival and minimizes saltwater intrusion. Collectively, the evidence indicates that managed inflows can bolster accretion and sustain forest function, and long-term resilience requires hydrologic restoration at landscape scales coupled with site-level actions that secure recruitment and address local degradation trajectories. These include freshwater and sediment introduction, protection from herbivory, and, in some cases, planting. Our research findings have important implications for worldwide CFWs, and tidal freshwater ecosystems in general, which occur mainly in tropical deltas. Full article

In August 2022, the Pearl River flooded portions of Jackson, Mississippi and temporarily closed the city’s water treatment plant, leaving most citizens without access to safe drinking and potable water for more than a month. This event punctuated an ongoing water crisis that had lingered for decades in this predominately African American city. We employ a social production of disaster approach to reveal aspects of slow violence perpetrated against disadvantaged peoples that increased their collective vulnerability to flood risks and limited their access to safe water. Using survey data collected one year after the flood, we examine event-related psychosocial stress as measured by the Impact of Event Scale and associated risk factors related to Conservation of Resources Theory. Multivariate analysis indicates that resource losses from the flood, health concerns about water quality, and trust in government were significantly related to elevated levels of psychosocial stress. Although the 2022 Pearl River flood can be treated as a discrete event, a social production of disaster perspective situates the flood in terms of its cascading effects and cumulative impacts on the city’s water infrastructure and citizens who depend on it. Full article

Suspended sediment plays a critical role in river ecosystem health, nutrient transport, and water quality, while also affecting navigation infrastructure and reservoir sedimentation in regulated rivers. A sound understanding of sediment dynamics in complex river systems consisting of natural lakes and engineered navigation structures remains a critical challenge for river management and water quality assessment. This study investigates the longitudinal patterns of suspended sediment concentration (SSC) along a ~500-km reach of the Upper Mississippi River containing Lake Pepin and multiple lock-and-dam structures. In this study, we analyze remotely sensed SSC estimates from the RivSED database (2001–2019). The SSC datasets were then integrated with in situ streamflow measurements and potential soil erosion to characterize sediment supply and transport dynamics and relate with upstream contributing watershed’s attributes. Results reveal distinct sediment behavior patterns: (1) Lake Pepin functions as a significant sediment trap, creating a clear discontinuity in SSC with mean concentrations decreasing from ~25 mg/L upstream to ~13 mg/L within the lake; (2) longitudinal SSC profiles show re-establishment patterns downstream of the lake, reaching ~23 mg/L approximately 100 km below the outlet; (3) strong positive correlation (r = 0.80, R² = 0.64, p < 0.001) exists between watershed sediment export and river-reach-scale sediment fluxes. Temporal analysis across these upstream monitoring stations shows sediment export rates ranging from 10,000 to 200,000 tons/year, with notable inter-annual variability driven by discharge patterns. This research demonstrates the utility of combining a spectrum of datasets for exploring sediment dynamics in complex riverine systems. Though the current study is a case study, the study results provide crucial insights for navigation management, ecosystem health assessment, and watershed management strategies in similar settings. Full article

Growing agricultural water demand, driven by climate change and land-use intensification, is accelerating global water scarcity and threatening food and environmental security. This study quantifies spatiotemporal changes in crop water requirements (CWR) and irrigation water requirement (IWR) from 1980 to 2017 for wheat, maize, and soybean. A corrected FAO crop coefficient method was used to estimate global CWR, while the logarithmic mean Divisia index (LMDI) was applied to decompose its drivers into climate and crop area changes. IWR was calculated to evaluate the increasing water stress in four representative river basins: the Haihe (HRB), Yellow (YRB), Mississippi (MRB), and Ganges (GRB) river basins. Multiple linear regression models were used to identify dominant drivers of water stress. Results show that from 1980 to 2017, CWR increased significantly for maize (+210 × 10⁸ m³) and soybean (+523 × 10⁸ m³) primarily due to crop area expansion, while wheat CWR declined (−109 × 10⁸ m³). Area growth contributed over +850 × 10⁸ m³ to global CWR increases. At the basin scale, IWR rose notably in HRB, YRB, and GRB, but declined in MRB. Regression analysis confirms that crop area change was the dominant driver of variations in IWR, particularly for soybean in HRB and maize in YRB, while precipitation exerted strong negative effects in some regions. This study provides a scalable framework for diagnosing agricultural water stress and its key drivers, supporting climate adaptation and irrigation planning under global change. Full article

Invasive insects increasingly threaten ecosystems worldwide, with wetlands especially vulnerable to unpredictable climate. Phragmites australis is a dominant plant species in Louisiana’s Mississippi River Delta and a critically important component of the wetland ecosystem. However, the invasive scale insect, Nipponaclerda biwakoensis, has contributed to large-scale dieback of this foundation species, jeopardizing erosion control, water filtration, and wildlife habitat. Despite rapid regional spread, the fine-scale dispersal of N. biwakoensis within host plants remains poorly understood. We examined whether the crawler-stage of N. biwakoensis scales preferentially settled on the bottom or top sections of P. australis stems, and whether plant nutritional and/or defensive traits shaped this preference. In field surveys, scale densities varied along the length of P. australis stems, with gravid females occurring 3.5× more frequently at the stem base than at the top; parasitism rates were similarly elevated, reaching 12× higher at the base. To evaluate potential drivers of this pattern, we quantified carbon, nitrogen, water, and phenolic content in lower and upper stem tissues and conducted complementary laboratory assays to test crawler settlement preferences. Under controlled conditions, crawlers settled most densely on middle stem sections, with lower densities at the base and the fewest near the top. The basal sections also contained 50% less nitrogen and 47% lower phenolic concentrations compared to the upper stem. The divergence in crawler settlement patterns between field and controlled conditions likely reflects the influence of additional environmental factors present in the field—such as habitat structure, microclimate, and natural enemies—that are absent or minimized in laboratory conditions. By applying a trait-based approach to insect dispersal, we link plant functional traits to N. biwakoensis crawler settlement patterns, strengthening our understanding of of insect distribution and guiding predictions of long-term dispersal in N. biwakoensis. Full article

Freshwater mussels (Unionida) perform important functions that are integral to keeping streams, rivers, and lakes operating as holistic ecosystems. Some of these functions improve water quality for humans through their filtration activities such as nutrient cycling and feces and pseudofeces production. In this study, we estimated the magnitude of contaminant sequestration by mussel assemblages using data at polluted and relatively unpolluted sites from watersheds in the upper Mississippi River (Minnesota, Wisconsin, Iowa, and Illinois, USA), the Clinch River (Virginia and Tennessee, USA), and the upper Neuse River (North Carolina, USA). Data from these rivers represented a range of (1) spatial scales from wadable streams to large rivers, (2) population sizes from tens of thousands to hundreds of millions of mussels, (3) survey techniques from qualitative to quantitative, and (4) chemical classes from inorganic to organic contaminants. We estimated that mussels in two relatively unpolluted reaches of the upper Mississippi River sequestered 1.42 × 10¹³ µg of total metals, metalloids, and ions (i.e., 14.2 metric tons). Mussels in the relatively unpolluted upper Neuse River sequestered between 22.2 and 53.3 million ng of polycyclic aromatic hydrocarbons (PAHs; i.e., 22.2–53.3 mg). Mussels at a polluted site in the Clinch River (Pendleton Island) sequestered 168 million ng of PAHs, compared to 1.45 billion ng of PAHs sequestered at relatively unpolluted sites. Mussels at unpolluted sites in the Clinch River had a 10 times greater sequestration capacity despite having lower tissue concentrations. The accuracy (precision and bias) associated with estimating assemblage-level contaminant sequestration by mussels varied as a function of survey design, spatial scale, population size, and contaminant type. This preliminary assessment of sequestration of contaminants by mussels outlines a framework for understanding the contributions these organisms make in supporting water quality and highlights the need to protect and conserve mussels and the ecosystem functions and services they provide. Full article

Reactive iron is a key driver of organic carbon preservation in marine sediments, but its participation in organic carbon remineralization complicates efforts to mechanistically constrain its role in preservation. To address this, we investigated the dual role of iron in the Mississippi River-influenced shelf sediment during low discharge (August 2016) and high discharge (May 2017). Duplicate sediment cores (30 cm depth) were collected from two stations; one core served as a natural reference, while the other was used for an incubation experiment. In the natural cores, reactive iron concentrations in the upper 9 cm were lower in August 2016 than in May 2017, whereas iron-bound organic carbon exhibited the opposite temporal pattern. Post incubation, approximately 10% of iron-bound organic carbon was lost at the offshore stations compared to a substantially greater loss (~59%) at the near-shore station. These results suggest that offshore regions may sustain more efficient organic carbon preservation via reactive iron, whereas the mechanism is considerably less effective in near-shore settings. Such spatial heterogeneity introduces significant uncertainty into current assessments of iron-mediated long-term organic carbon preservation on a global scale and underscores the need for more comprehensive investigations of iron–organic carbon interactions in continental shelve sediments. Full article

Temporal resolution of carbon dioxide (CO₂) release from the soil at the field scale is not completely understood. The objectives of this study were to identify trends, repetitive cycles, and residual patterns and structures with a time-series analysis from a furrow-irrigated corn (Zea mays L.) field with and without cover crops (i.e., CC and No-CC, respectively) over the course of one growing season in the Lower Mississippi River Basin. Carbon dioxide fluxes were measured from 5 May to 18 August 2024, four times a day (i.e., 0300, 0900, 1500, and 2100 h) from each of the two CC treatments. Linear trends were significant, but they were only able to explain 3 and 10% of the CO₂-flux variability for CC and No-CC, respectively. Spectral density analyses indicated the significant presence of repetitive patterns every four lags, the amplitude of which was numerically 25% greater for CC than for No-CC. The structure of the residual was best described by separate autoregressive-moving-average (ARMA) models for the CC and No-CC treatments. The current study provides preliminary yet fundamental information to improve the understanding of the dynamics of soil respiration processes from a row-crop production system. Full article

The estuaries of the Mississippi River Delta are among the most productive coastal ecosystems in the world and have attracted human fishing communities for centuries. Beginning in the early 20th century, the oil and gas industry also emerged as a powerful economic force in exploiting coastal fossil fuel deposits. This paper reviews the complex history of the oil and gas industry in Southeast Louisiana, including its relationships with political corruption, inequality, pollution, and environmental catastrophe; and also its role in supporting coastal fishing communities with complementary economic opportunities. In the 21st century, a series of disasters—above all Hurricane Katrina in 2005 and the B.P. oil spill in 2010—drew attention to the risks inherent to the region, as well as its crucial role in buffering the impacts of tropical storms for inland urban communities. This paper examines the evolution of fisheries regulations and their consequences of small-scale fishers, focusing especially on the banning of gill net use in 1990s. By combining historical information with ethnographic interviews and participant observation, this paper examines the complex political–economic forces involved in shifting regulatory frameworks and policies, and it shows their negative consequences for fishing communities facing an existentially threatening combination of coastal erosion, fisheries declines, and various macroeconomic headwinds. This paper argues that resilient coastal communities are crucial to combating the environmental problems facing coastal regions and that rethinking fisheries regulations may be a dynamic tool in enhancing community resilience. Full article