Coastal Louisiana Research Articles

Impacts of dispersants on microbial communities and ecological systems.

Accidental oil spills can result in catastrophic ecological insults and therefore require rapid intervention to mitigate the potential impacts to aquatic ecosystems. One of the largest oil spills, known as the Deepwater Horizon oil spill, occurred in the Spring of 2010 near the coast of Louisiana (USA) due to an explosion during oil drilling activities. Millions of gallons of oil were released into the Gulf of Mexico, impacting thousands of ocean miles and coastal areas linked to the gulf. Among the actions taken during the remediation efforts was the unprecedented large use of Corexit dispersants, including at the subsurface to prevent oil from reaching the surface. While there is evidence that dispersants can accelerate the biodegradation of oil, reports on their potential toxicity to aquatic biota and to microbial functions have also been documented. In this review, we will examine the most recent literature on the impact of dispersants on microbial communities implicated in oil degradation and overall ecological networks. The primary focus will be on studies using Corexit but other dispersants will be discussed if data are available. We will share the literature gaps identified and discuss future work that is needed to reconcile some of the discrepancies found on the effectiveness of dispersants on oil degradation and their potential toxicity. KEY POINTS: • Chemical dispersants have been applied as a chemical response measure for oil spills. • The effects of chemical dispersants on microbial communities have been the subject of substantial research. • This work seeks to review recent work on the impact of chemical dispersants on oil biodegradation, microbial communities, and ecosystems.

Restoration otherwise: Towards alternative coastal ecologies

This article considers how to rethink ecological restoration as a process tethered to ongoing formulations of racial and environmental justice. It is situated in the context of coastal Louisiana's wetland loss crisis and the state's unprecedented investment in large-scale wetland restoration projects as a technoscientific fix that comes at the expense of several small, Black and Indigenous bayou communities. Critical of approaching restoration as a practice predicated on loss and return, this article builds upon scholarship in Black and Indigenous ecologies and ethnographic fieldwork among Black coastal communities in southeast Louisiana to reimagine restoration as an intergenerational, socioecological set of practices grounded in cultivating cultural continuity and community care across time and space. Working with the Black feminist geographic concepts of the plot and the shoal, the article develops the notion alternative restorations—or restoration otherwise—around three reformulations of restoration: As a practice of cultural continuity, as a mode of cultivating self-reliance, and as a scientific practice of integrity and humility. It concludes by reflecting the ways Black ecological practices and values can shift the course of restoration science toward sustaining Black life in the era of climate change.

Sources and chemical stability of soil organic carbon in natural and created coastal marshes of Louisiana

Coastal marshes are globally important for sequestering carbon, yet sea-level rise and anthropogenic stressors can reduce their capacity as carbon sinks. Marsh restoration can offset a portion of carbon loss through the degradation of natural marshes, but potential differences in the sources and stability of soil organic carbon (SOC) between created and natural marshes may affect their function as a long-term carbon sink. Here, we examine the sources and chemical stability of SOC in natural and created marshes across the Gulf coast of Louisiana, USA. Marshes were examined along an estuarine salinity gradient in a former interdistributary basin of the Mississippi River Delta and in six created marshes across a 32-year chronosequence and a natural reference marsh (n = 6) in the Chenier Plain. Carbon source was assessed using δ13C analysis and chemical stability was determined through an acid hydrolysis digestion that removed labile carbon (LC). Soil δ13C values suggested that the local vegetation dominated SOC in all natural marshes although brackish marshes had a mix of sources and degradation of SOC. Recalcitrant carbon (RC) was 72.2 ± 0.5 % of SOC across fresh, brackish and saline marshes. The depth-averaged RC accumulation rate was almost three times greater than LC accumulation rate, yet both contributed significantly to accretion and long-term SOC accumulation (124–132 g m−2 y−1 in natural marshes). RC and SOC accumulation rate increased with mineral sediment accumulation rate. For the created marshes, SOC became increasingly recalcitrant due to an increase in in-situ plant inputs, but accumulation rates were lower than the natural marshes. Overall, this study illustrates that natural marshes have a large stock of RC from the vegetation while dredge sediment created marshes have no plant-derived carbon initially, which accumulates slowly thereafter. Restoration practices may be improved by preserving and augmenting these deteriorating but carbon-rich natural marshes.

Deepwater Horizon Oil Spill Exposures and Long-term Self-rated Health Effects Among Parents in Coastal Louisiana.

To assess whether exposure to the 2010 Deepwater Horizon oil spill (DHOS) was related to parents' self-rated health over time. 3 waves of panel data were drawn from the Gulf Coast Population Impact study (2014) and Resilient Children, Youth, and Communities study (2016, 2018). Coastal Louisiana communities in high-impact DHOS areas. Respondents were parents or guardians aged 18 - 84, culled from a probability sample of households with a child aged 4 to 18 (N = 526) at the time of the 2010 DHOS. Self-rated health was measured at each wave. Self-reported physical exposure to the DHOS, economic exposure to the DHOS, and control variables were measured in 2014. We used econometric random effects regression for panel data to assess relationships between DHOS exposures and self-rated health over time, controlling for potentially confounding covariates. Both physical exposure (b = -0.39; P < 0.001) and economic exposure (b = -0.34; P < 0.001) to the DHOS had negative associations with self-rated health over the study period. Physical exposure had a larger effect size. Parents' physical contact with, and economic disruption from, the 2010 DHOS were tied to long-term diminished health.

Assessment of inland flood hazard sensitivity to hydrological intensification in coastal watersheds

IntroductionIntensification of the hydrologic cycle induced by climate variability and landscape modification is expected to increase the frequency of extreme flood events. Multi-jurisdictional approaches to manage inland flood risks at watershed scales demand the ability to objectively assess not only future flood potentials, but to also set priorities based upon multiple factors such as the stream channels most sensitive to hydrologic stress.MethodsThis study presents a method to estimate flood hazard sensitivities to increasing stormwater runoff due to hydrologic intensification (e.g., urbanization, climate effects) on local and watershed scales. The method is demonstrated in the low-gradient inland watershed regions of southwestern coastal Louisiana, USA. Utilizing highly detailed numerical models from the Federal Emergency Management Agency (FEMA), absolute and relative flood sensitivities were calculated for 45 flood-prone stream channels in the Lafayette, LA region. Channel sensitivities to flood hazards induced by changes in the 10-yr (10% annual exceedance probability) flood flows were quantified by analysis of 485 scenarios developed using a downward counterfactual scaling strategy.Results and discussionRelying entirely upon publicly available numerical models and input datasets, the study revealed key information about the relationship between estimable hydraulic characteristics (e.g., conveyance, resistance, and flow) and absolute and relative flood hazard sensitivity measures on a per-channel basis. Information from the subset of detailed numerical models was efficiently leveraged to provide a regional map of relative flood sensitivities. The methodology is robust and can be applied in very general settings to address the concern of hydrologic intensification in practical flood risk management applications.

“Ground Zero” for Climate Crisis: Narratives About Climate Adaptation and Implications for Justice in Coastal Louisiana

Decisions about climate change adaptation are informed by technical information, but they are also shaped by social and political factors and impacted communities. Given the realities of a changing climate, more research is needed to examine how technically trained practitioners and other actors describe their work in relation to social and political factors. This article contributes to knowledge on this topic by analyzing the narratives of 62 organizational actors in coastal Louisiana. Actors include scientists, engineers, modelers, planners, project administrators, government staff, and non‐profit employees working on climate adaptation and coastal risk reduction projects outlined in Louisiana's Coastal Master Plan. While scholars critique the Master Plan as overly technocratic, I show that people weave morals and values into narratives about science. However, I show how the motivations of acting boldly, morally, and urgently in the face of emergency clash with climate justice. Some individuals within these organizations do advocate for reforming or rethinking Master Plan projects to better serve coastal communities; however, these individuals also face resistance from colleagues who frame this work as secondary or outside of their organizational purview. To conclude, I argue that research connecting technical aspects of climate adaptation planning to power and social justice outcomes has the potential to bridge disciplinary divides.

An effective online platform for crowd classification of coastal wetland loss

AbstractWetland loss is increasing rapidly, and there are gaps in public awareness of the problem. By crowdsourcing image analysis of wetland morphology, academic and government studies could be supplemented and accelerated while engaging and educating the public. The Land Loss Lookout (LLL) project crowdsourced mapping of wetland morphology associated with wetland loss and restoration. We demonstrate that volunteers can be trained relatively easily online to identify characteristic wetland morphologies, or patterns present on the landscape that suggest a specific geomorphological process. Results from a case study in coastal Louisiana revealed strong agreement among nonexpert and expert assessments who agreed on classifications at least 83% and at most 94% of the time. Participants self‐reported increased knowledge of wetland loss after participating in the project. Crowd‐identified morphologies are consistent with expectations, although more work is needed to directly compare LLL results with previous studies. This work provides a foundation for using crowd‐based wetland loss analysis to increase public awareness of the issue, and to contribute to land surveys or train machine learning algorithms.

The Painted Bunting: A Songbird Facing Multiple Threats

The Painted Bunting: A Songbird Facing Multiple Threats Charles E. Konrad The Painted Bunting is unquestionably the most colorful songbird in the southern United States (cover photo, Figure 1). The male exhibits dazzling splashes of blue, green, yellow, and red plumage, and the reserved female possesses a solid coat of bright green, which blends in with the brush and trees where the nest is located. Because of its limited geographical range and stealthy nature, relatively few birders have experienced the delight of seeing this bird, and its dramatically declining population (Dybas 2018) has further reduced the chances of spotting it. Click for larger view View full resolution Figure 1. Painted Bunting taken at Huntington Beach State Park in South Carolina on May 16, 2022. [End Page 293] The Painted Bunting is categorized into two subspecies that are nearly identical in appearance but display distinct geographical distributions separated by a distance on the order of 500 km (Yirka et al. 2021). The eastern subspecies, Passerina ciris, breeds in a region that stretches from coastal North Carolina to northern Florida and includes an inland area in southern South Carolina and southeastern Georgia. The western subspecies, Passerina pallidior, breeds in a region extending from coastal Louisiana and Texas northward to southeastern Kansas and southern Missouri (Yirka et al. 2021). During the fall, the eastern population migrates southward to southern Florida and portions of the Bahamas and Cuba, while the western population migrates to portions of coastal Mexico and Central America. Given their geographic separation, these two populations no longer interact or breed, suggesting that the Painted Bunting will eventually divide into two different bird species (Dybas 2018). Within its breeding region, the Painted Bunting is typically present in bushy areas and woodland edges, often staying hidden within the dense cover of the vegetation. The males may be spotted by looking in the direction of their warbling songs during the breeding season. They often appear on an exposed perch higher up in the brush or trees. While the male sings out to announce its territory, the female typically remains hidden in the brush near the nest. In suitable habitats, both the male and female may be seen frequenting bird feeders. There has been a concerning decline in the number of Painted Buntings over the last fifty-plus years. According to the Breeding Bird Survey, the bird’s combined eastern and western populations have declined about 55 percent over the last thirty years (Dybas 2018). Springborn and Meyers (2005) report that the estimated number of individuals in the eastern population, Passerina ciris, decreased by about 75 percent between 1966 and 1996. Since 1996, this population has become so sparse in places that it is difficult to get a handle on the population trends across the southeastern US (Meyers 2011). Concern for the decline in the eastern and western populations of the bird species prompted the U.S. Fish and Wildlife Service and Partners in Flight (Springborn and Meyers 2005) to identify the Painted Bunting as a “species of concern” and a “near threatened” species. Several factors have been tied to the decline in Painted Bunting populations. Habitat loss in the summer breeding areas is unquestionably a major factor in the rapid reduction of the eastern population (Meyers 2011, Springborn and Meyers 2005). Painted Buntings are most common in dense marine shrubs, particularly live oak, which occur along the coast, largely on the barrier and sea islands from the Carolinas southward to Georgia and northern Florida (Meyers 2011, Dybas 2018). Many of these islands have seen rapid residential and commercial development over the last several decades, and this has greatly diminished the acreage of the Painted Bunting’s breeding habitat. In addition, many of the individuals in this eastern population winter in South Florida, which has seen a similar pattern of development and consequent habitat loss. Also, the reduction in riparian habitats near the southern US and Mexican coastlines, which are used during migration by the western population, have further contributed to the population decline (Lowther et al. 1999, Sykes and Holzman 2005). Given its extraordinary colors and beauty, the Painted Bunting has unfortunately been trapped in portions of its wintering grounds and sold as a...

French on Shifting Ground: Cultural and Coastal Erosion in South Louisiana by Nathalie Dajko

Reviewed by: French on Shifting Ground: Cultural and Coastal Erosion in South Louisiana by Nathalie Dajko Carole Salmon Dajko, Nathalie. French on Shifting Ground: Cultural and Coastal Erosion in South Louisiana. UP of Mississippi, 2020. ISBN 978-1-4968-3093-7. Pp. xviii +184. Sociolinguists specializing in Louisiana French have long established its steady decline since the beginning of the twentieth century, despite cultural revival movements and linguistic preservation efforts that started after World War II. Simultaneously, during all those decades, geographers have been monitoring the erosion of coastal marshes in the Gulf of Mexico, which constitute the southern border of the Pelican State and the base of what is called the Acadiana triangle. As Dajko explains, causes leading to such land erosion are numerous and complex, but she aims at exploring “the theoretical construct of place and the role that language [...] plays in its construction” (12). This region is composed of twenty-two parishes and her study focuses on two in particular: Lafourche and Terre- bonne, where French-speaking Cajuns historically settled and where their culture and identity are still vibrant, even if their language is shifting to English. Moreover, other varieties of French and Creole can be found, and Dajko offers a detailed inventory of those varieties in southern Louisiana. About a hundred years ago, the future of French started to be threatened when in 1921, a change to the State’s constitution made English the mandatory language of schooling. Even though some researchers, such as Michael Picone (1997), have previously linked language and land, Dajko’s extensive study specifically explores the loss of the language (here, French) with the loss of the place (here, coastal marshes). Since pieces of land the size of a football field are disappearing in the Gulf at a rapid pace, the correlation between land erosion and language loss in French-speaking communities in coastal southern Louisiana is evident—and frightening. Dajko’s fieldwork is composed of around 250 interviews with local French speakers, collected between 2006 and 2008 in Terrebonne and Lafourche parishes. The volume provides extensive descriptions of the demographic history as well as economic factors in the area being studied, which helps the reader understand how important these communities’ connection to their land has been—but also how, ironically, some of their activities have contributed to land erosion, especially the cutting of canals for the oil industry. By reading this volume, one can fully understand the connections between land, language, and what Dajko calls— referring to her participants’ answers—“bayou identity.” The author shares her results from surveys in perceptual linguistics, such as verbal guise tests, cultural domain tests, and maps drawings, which allowed her to measure language ideology features and identity perception among her Lafourche and Terrebonne participants. She also offers a linguistic landscape study of bayou Point(e) au(x) chêne(s)—or for some, Point(e) au(x) chien(s), those two toponymic variants underlying various identities among this place. Dajko’s study clearly establishes that when it [End Page 230] comes to their own identity perception, French-speaking participants consider that belonging to a place (bayou identity) is more important than ethnic belonging. French in Terrebonne-Lafourche is enregistered (linguistic features have become associated with social features, 127) because of language death, therefore confirming the place-based identity of those French-speaking communities. [End Page 231] Carole Salmon Furman University (SC) Copyright © 2022 American Association of Teachers of French

Genetic diversity and family groups detected in a coyote population with red wolf ancestry on Galveston Island, Texas

BackgroundHybridization can be a conservation concern if genomic introgression leads to the loss of an endangered species’ unique genome, or when hybrid offspring are sterile or less fit than their parental species. Yet hybridization can also be an adaptive management tool if rare populations are inbred and have reduced genetic variation, and there is the opportunity to enhance genetic variation through hybridization. The red wolf (Canis rufus) is a critically endangered wolf endemic to the eastern United States, where all extant red wolves are descended from 14 founders which has led to elevated levels of inbreeding over time. Red wolves were considered extirpated from the wild by 1980, but before they disappeared, they interbred with encroaching coyotes creating a genetically admixed population of canids along coastal Texas and Louisiana. In 2018, a genetic study identified individuals on Galveston Island, Texas with significant amounts of red wolf ancestry. We collected 203 fecal samples from Galveston for a more in-depth analysis of this population to identify the amount of red wolf ancestry present and potential mechanisms that support retention of red wolf ancestry on the landscape.ResultsWe identified 24 individual coyotes from Galveston Island and 8 from mainland Texas with greater than 10% red wolf ancestry. Two of those individuals from mainland Texas had greater than 50% red wolf ancestry estimates. Additionally, this population had 5 private alleles that were absent in the North American reference canid populations used in this study, which included 107 southeastern coyotes, 19 captive red wolves, and 38 gray wolves, possibly representing lost red wolf genetic variation. We also identified several individuals on Galveston Island and the mainland of Texas that retained a unique red wolf mitochondrial haplotype present in the red wolf founding population. On Galveston Island, we identified a minimum of four family groups and found coyotes on the island to be highly related, but not genetically depauperate. We did not find clear associations between red wolf ancestry estimates and landscape features, such as open green space or developed areas.ConclusionOur results confirm the presence of substantial red wolf ancestry persisting on Galveston Island and adjacent mainland Texas. This population has the potential to benefit future red wolf conservation efforts through novel reproductive techniques and possibly through de-introgression strategies, with the goals of recovering extinct red wolf genetic variation and reducing inbreeding within the species.

Trophic Position of Wintering Common Loons (Gavia immer ) in Barataria Bay, Louisiana Following the Deepwater Horizon Oil Spill

Common Loons (Gavia immer) wintering in watercourses of Barataria Bay, in coastal Louisiana were sampled in 2011–2014 following the Deepwater Horizon oil spill of 2010. Blood samples were analyzed for stable isotope ratios of carbon, nitrogen and sulfur as proxies for habitat use and diet in order to expand our understanding of the trophic position of wintering loons. The δ 13C and δ 34S values indicated that these Common Loons feed in coastal estuarine habitats. Trophic position was estimated indirectly by comparing loon stable isotope ratios with those of Brown Pelicans (Pelecanus occidentalis), a known piscivore, sampled concurrently in 2014. The isotopic signatures of the two species were not significantly different; this is consistent with the hypothesis that both species foraged primarily in coastal estuarine habitats and mainly as piscivores. No significant differences were found between subadult and adult Common Loons with respect to isotopic signatures, suggesting similar habitat usage and diet. Adults weighed more and were in better body condition than subadults. Stable isotope composition and body condition were not significantly related. Using a parallel data set of polycyclic aromatic hydrocarbons (PAH, an indicator or oil contamination) in the blood of the same loons, there was no significant relationship between PAH contamination and stable isotopic composition. Therefore, PAH-contamination could not be linked to a distinctive foraging habitat or diet.

From Grains to Plastics: Modeling Nourishment Patterns and Hydraulic Sorting of Fluvially Transported Materials in Deltas

AbstractUnderstanding the way fluvially transported materials are partitioned in river deltas is essential for predicting their morphological change and the fate of environmental constituents and contaminants. Translating water‐based partitioning estimates into fluxes of nonwater materials is often difficult to constrain because most materials are not uniformly distributed in the water column and may have characteristic transport pathways that differ from the mean flow. Here, we present a novel reduced‐complexity modeling approach for simulating the patterns of transport of a diverse range of suspended fluvial inputs influenced by vertical stratification and topographic steering. We utilize a mixed Eulerian‐Lagrangian modeling approach to estimate the patterns of nourishment and connectivity in the Wax Lake and Atchafalaya Deltas in coastal Louisiana. Using the reduced‐complexity particle routing model dorado, in conjunction with a calibrated ANUGA hydrodynamic model, we quantify how transport patterns in each system change as a function of a material's Rouse number and environmental conditions. We find that even small changes to local topographic steering lead to emergent system‐scale changes in patterns of fluvial nourishment, with greater channel‐island connectivity for positively buoyant materials than negatively buoyant materials, hydraulically sorting different materials in space. We also find that the nourishment patterns of some materials are more sensitive than others to changes in discharge, tidal conditions, and anthropogenic dredging. Our results have important implications for understanding the eco‐geomorphic evolution of deltas, and our modeling framework could have interdisciplinary implications for studying the transport of materials in other systems, including sediments, nutrients, wood, plastics, and biotic materials.

Deep Learning–Based Building Attribute Estimation from Google Street View Images for Flood Risk Assessment Using Feature Fusion and Task Relation Encoding

Floods are the most common and damaging natural disaster worldwide in terms of both economic losses and human casualties. Currently, policymakers rely on data collected through labor-intensive and, consequently, expensive street-level surveys to assess flood risks. We propose a laborless and financially feasible alternative: a framework that can effectively and efficiently collect building attribute data without manual street surveys. By utilizing deep learning, the proposed framework analyzes Google Street View (GSV) images to estimate multiple attributes of buildings simultaneously—including foundation height, foundation type, building type, and number of stories—that are necessary for assessing flood risks. The proposed framework achieves a 0.177-m mean absolute error (MAE) for foundation height estimation and classification F1 scores of 77.96% for foundation type, 83.12% for building type, and 94.60% for building stories, and requires less than five days to predict the attributes of 0.8 million buildings in coastal Louisiana.

Family Album: Stories by Gabriela Alemán

Reviewed by: Family Album: Stories by Gabriela Alemán Lanie Tankard Gabriela Alemán Family Album: Stories Trans. Dick Cluster & Mary Ellen Fieweger. San Francisco. City Lights Books. 2022. 120 pages. THE EIGHT SHORT stories in Family Album live up to the book's title, their names underscoring the concept: Baptism, Summer Vacation, School Trip, Family Outing, Marriage, Honeymoon, Costume Party, Moving Day. Ranging from eight to fifteen pages, these tales offer an astute portrait of author Gabriela Alemán's country, called Ecuador for the equator upon which it resides. Settings bounce from the capital of Quito high in the Andean foothills to the volcanic archipelago of the Galápagos Islands—but also a drilling platform near the Louisiana coast, Puerto Rico, a Brooklyn laundromat, Mexico, and the Faena Theater and Hotel in Buenos Aires. Storylines intrigue: a dying man wants to scuba dive for sunken treasure using Robinson Crusoe's map; memories of a 1967 biddy basketball match drive a man to drink; and John Wayne Bobbitt brings his reconstructed career to Argentina. Murder and mayhem abound along the Ecuadorian Amazon. Born in Brazil, Alemán draws on her journalistic experience as she toys with the short-story form. Clever noir blends fact and fiction with an amusing dash of the gothic, resonating César Aira, Carlos Fonseca, Italo Calvino, or Silvia Moreno-Garcia. "Costume Party" nods to Chilean writer Roberto Bolaño's 2666 ("The Part about Fate"), exploring movies about masked professional prizefighter El Santo, a symbol of justice in Mexico. The narrator believes there was a double in one film shot in Ecuador, terming the series a "house of cards, fragile." [End Page 66] A widow spins one of the strongest yarns in "Marriage" as she discovers her recently deceased husband led a double life. Cleaning out his desk in Quito, she sees he had another wife and children in Machala while funneling money for a construction company—and realizes "the hall of mirrors that my life had been." Each allegorical tale stands effectively on its own. Yet, dig deeper and therein resides Alemán's genius, for she embeds recent events such as the Brazilian Odebrecht scandal's connection to Ecuador or the power dynamics of oil versus Indigenous rights. She tosses hints all over the place. For example, "Moving Day" seems merely a fascinating tale of demonic possession until one ponders a character's name and recognizes what a Portuguese word indicates. Gabriela Alemán's compelling snapshots may be of Ecuador, but their relatives certainly appear in many family albums around the globe. The book is a work of art. Lanie Tankard Austin, Texas Copyright © 2022 World Literature Today and the Board of Regents of the University of Oklahoma

E&amp;P Notes (November 2022)

E&amp;P Notes (November 2022)

The Impact of Levee Openings on Storm Surge: A Numerical Analysis in Coastal Louisiana

The existence of the Mississippi River (MR) and Tributaries’ levees in coastal Louisiana could block storm surge and cause surge setup in adjacent basins. In order to reduce storm surge amplification caused by these barriers, one possible solution is to build “floodways” through the mainstem MR levees to allow surge during tropical events to cross. The primary purpose of this study is to examine if these floodways/openings can help reduce storm surge in adjacent basins. Using Hurricane Isaac (2012) as an example, a pre-validated Delft3D-based hydrodynamic model was applied to study the effect of levee openings on storm surge. Model results and flux analysis show that these levee openings were not effective in reducing storm surge in Barataria Basin and Breton Sound due to the complex interaction between the cross flow from the surge and the MR flow. During Isaac, the MR water could be diverted to Barataria and/or Breton, which resulted in an increase in storm surge, essentially defeating the primary objective of the levee openings. Overall, the impact of levee openings at the selected locations on storm surge reduction in adjacent basins of coastal Louisiana was minor and very limited.

Coastal wetland area change for two freshwater diversions in the Mississippi River Delta

Coastal systems around the globe are being re-integrated with adjacent river systems to restore the natural hydrologic connection to riparian wetlands. The Mississippi River sediment diversions or river reconnections are one such tool to combat high rates of wetland loss in coastal Louisiana, USA by providing freshwater, sediment, and nutrients. There has been some disagreement in the published literature whether re-establishing river reconnection is slowing or contributing to coastal wetland loss. This issue is due to the difficulties in the application of remote sensing in low-relief environments where water level changes could indicate either land loss or simply temporary submergence. We analyzed land change at the receiving areas of two existing freshwater river diversions, Davis Pond and Caernarvon, which have been intermittently receiving river water for up to 2+ decades. This study provides a robust analysis of wetland land change rates in proximity these river diversions including years before river reconnection. Our analyses indicate a net land gain since river reconnection operations began at Davis Pond Diversion (+3.42 km2; range: +2.02–4.81 km2) and no statistically significant change at the Caernarvon Diversion. The Davis Pond wetland results are corroborated with data from a decadal field study documenting increased inorganic sedimentation in the soil. It is clear from this study and others, that river reconnection can increase or, in the case of Caernarvon, have no statistical effect on the land change in these systems due to differences in vegetation, hydroperiod, sediment delivery and external factors including hurricane impacts. Our remote sensing analysis was compared with a global water area change analysis mapping tool which also supported our findings.

Performance of Paid and Volunteer Image Labeling in Citizen Science — A Retrospective Analysis

Citizen science projects that rely on human computation can attempt to solicit volunteers or use paid microwork platforms such as Amazon Mechanical Turk. To better understand these approaches, this paper analyzes crowdsourced image label data sourced from an environmental justice project looking at wetland loss off the coast of Louisiana. This retrospective analysis identifies key differences between the two populations: while Mechanical Turk workers are accessible, cost-efficient, and rate more images than volunteers (on average), their labels are of lower quality, whereas volunteers can achieve high accuracy with comparably few votes. Volunteer organizations can also interface with the educational or outreach goals of an organization in ways that the limited context of microwork prevents.

Saltwater intrusion indirectly intensifies Phragmites australis invasion via alteration of soil microbes

Although global change clearly influences species invasion, the exact mechanisms by which global change either intensifies or limits invasive spread remain elusive. Global change can affect invasion directly by altering abiotic conditions, as well as indirectly by altering the abundance and composition of interacting species. Here we examine the relative impacts of direct effects of saltwater intrusion and indirect effects via microbial interactions on the expansion of a model invasive plant species, Phragmites australis, in freshwater marshes of coastal Louisiana. Using a mesocosm experiment, we found that overall salinity strongly increases invasion, but the direction and magnitude of direct and indirect effects were context dependent. Indirect effects of salinity, via alterations in soil microbial composition, increased invasive performance when grown in monoculture and decreased native performance in native-only communities. However, when P. australis and natives were grown together, microbial indirect effects were not important; rather the salinity treatment increased P. australis invasion through reduction of native plant growth. Results suggest that salinity-induced alteration of soil microbes will increase susceptibility of native communities to invasion and promote P. australis monoculture expansion in later stages of invasion; whereas non-microbial effects of salinity are more important in early stages of invasion when P. australis is competing with native species. More broadly, these results underscore the importance of considering microbially-mediated indirect effects of global change in investigating the long-term outcomes of plant species interactions.

Making and Mastering Violent Environments: Following the Infrastructures of Accumulation in Coastal Louisiana

AbstractLouisiana’s coastal wetlands have been disappearing at an alarming rate over the past several decades, with the greatest harm experienced by vulnerable populations (poor and racialised residents). It was not until 2005 that the state legislature responded with a much‐lauded Master Plan tasked with integrating the construction of new flood control infrastructure with wetland restoration. Seeking to unsettle this initiative, we develop a historical‐geographical materialist approach to follow the entanglements between infrastructural production and capital accumulation in Louisiana over the past several hundred years. In so doing, we present a two‐fold argument: that the making and mastering infrastructural violence has always been part of the historical unfolding of the socio‐spatial dynamics of capitalism; and that infrastructural development has played an integral role in this duality at every historical turn. The capitalist state, at both the federal and state levels, has played a vital role in producing and controlling this violence.