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1
Hohman, William L., Dennis W. Woolington e James H. Devries. "Food habits of wintering canvasbacks in Louisiana". Canadian Journal of Zoology 68, n.º 12 (1 de dezembro de 1990): 2605–9. http://dx.doi.org/10.1139/z90-362.
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We studied the food habits of canvasbacks (Aythya valisineria) at Catahoula Lake (inland) and the Mississippi River Delta (coastal), Louisiana, from November 1987 to February 1988. Plant foods comprised >97 aggregate percent dry mass of the canvasback diet. The proportion of plant material eaten did not vary with sex, age, or month, or differ between study sites or nocturnal and diurnal collections. Tubers of chufa flatsedge (Cyperus esculentus) and common arrowhead (Sagittaria latifolia) made up 94% of the canvasback diet at Catahoula Lake. Common and grassy arrowhead (Sagittaria graminea) tubers and American bulrush (Scirpus americanus) rhizomes and seeds formed 94% of the canvasback diet at the Mississippi River Delta. Consumption of specific food taxa did not vary with sex, age, or month at either study site. Canvasbacks at the Mississippi River Delta preferred seeds of American bulrush over all other foods, but American bulrush rhizomes were underrepresented in the diet. Densities of subterranean plant foods at Catahoula Lake and the Mississippi River Delta are apparently higher than at other major canvasback concentration areas and enable canvasbacks wintering in Louisiana to improve their physical condition before spring migration.
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White, Eric D., Ehab Meselhe, Denise Reed, Alisha Renfro, Natalie Peyronnin Snider e Yushi Wang. "Mitigating the Effects of Sea-Level Rise on Estuaries of the Mississippi Delta Plain Using River Diversions". Water 11, n.º 10 (28 de setembro de 2019): 2028. http://dx.doi.org/10.3390/w11102028.
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Using the Mississippi River as a tool for restoration has been a key element of restoration planning in Louisiana for decades. The results of allowing river water and sediment back into the coastal system are manifested in a number of places in present day Louisiana, with additional plans for large scale sediment and water diversions from the Mississippi River. Many previous numerical modeling studies have focused on sediment delivery to Louisiana estuaries. This study examines the effects of river diversions on salinity gradients in receiving estuarine basins. The Integrated Compartment Model, a planning-level model that simulates multi-decadal change in estuarine hydrodynamics and wetland systems under assumed sea-level rise scenarios, was used to assess the estuarine salinity gradient under potential management regimes. The simulations for current conditions are compared to a future 50-year simulation with additional diversions, as well as cases with a variety of diversion options. This modeling analysis shows that without additional action, 50-years of sea-level rise could result in substantial increases in salinity throughout the Mississippi Delta Plain estuaries. This can be largely offset with additional large river diversions which can maintain variable salinity gradients throughout the estuary basins.
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Zwiers, Maarten. "Plantationocene Geographies: Petro-Multinationals, Agribusiness, and the Racial Ecology of the Cold War Mississippi Delta". Global South 16, n.º 2 (março de 2023): 49–67. http://dx.doi.org/10.2979/gbs.2023.a908602.
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ABSTRACT: The Cold War Mississippi Delta figured prominently as a hotbed of massive resistance against racial integration and as a civil rights battleground, particularly during the 1950s and 1960s. It was also home to an agrochemical regime of plantation production that heavily impacted regional ecosystems. This essay addresses the interplay between white supremacist politics and environmentally destructive forms of large-scale farming, especially the connections between petrochemical manufacturing in Louisiana and plantation agriculture in Mississippi's Delta region. I discuss how a Jim Crow mindset manifested itself in these industries, with toxic repercussions for both society and nature. The petro-multinationals that settled along the Mississippi River were active in various parts of the planet, and the crops grown on Delta neoplantations were sold on world markets, making the activities of these companies distinctly global in character. This essay considers the factories in Louisiana and the largescale farms in the Mississippi Delta as part of a unified agrochemical entity that can be considered a Plantationocene geography: a globalized business conglomerate based on a racialized labor system and an extractive, for-profit logic that was detrimental to local communities and the environment. With the arrival of oil and gas plants in Louisiana and the rise of the neoplantation during the New Deal years, an industrialized and poisonous racial ecology began to develop in the southern Mississippi River Valley wherein water, land, and minerals served as resources for the enrichment of a select few.
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Zwiers, Maarten. "Plantationocene Geographies: Petro-Multinationals, Agribusiness, and the Racial Ecology of the Cold War Mississippi Delta". Global South 16, n.º 2 (março de 2023): 49–67. http://dx.doi.org/10.2979/globalsouth.16.2.04.
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ABSTRACT: The Cold War Mississippi Delta figured prominently as a hotbed of massive resistance against racial integration and as a civil rights battleground, particularly during the 1950s and 1960s. It was also home to an agrochemical regime of plantation production that heavily impacted regional ecosystems. This essay addresses the interplay between white supremacist politics and environmentally destructive forms of large-scale farming, especially the connections between petrochemical manufacturing in Louisiana and plantation agriculture in Mississippi's Delta region. I discuss how a Jim Crow mindset manifested itself in these industries, with toxic repercussions for both society and nature. The petro-multinationals that settled along the Mississippi River were active in various parts of the planet, and the crops grown on Delta neoplantations were sold on world markets, making the activities of these companies distinctly global in character. This essay considers the factories in Louisiana and the largescale farms in the Mississippi Delta as part of a unified agrochemical entity that can be considered a Plantationocene geography: a globalized business conglomerate based on a racialized labor system and an extractive, for-profit logic that was detrimental to local communities and the environment. With the arrival of oil and gas plants in Louisiana and the rise of the neoplantation during the New Deal years, an industrialized and poisonous racial ecology began to develop in the southern Mississippi River Valley wherein water, land, and minerals served as resources for the enrichment of a select few.
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Morris, Christopher. "Finding Louisiana: La Salle's Encounter with the Mississippi River Delta". Terrae Incognitae 36, n.º 1 (junho de 2004): 28–41. http://dx.doi.org/10.1179/tin.2004.36.1.28.
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Lu, Qimiao, Fred Scott, Yarzar Tun e Rob Nairn. "LONG TERM MORPHOLOGIC MODELLING OF DELTA DEVELOPMENT IN BRETON SOUND RESULTING FROM A PROPOSED DIVERSION STRUCTURE". Coastal Engineering Proceedings, n.º 37 (1 de setembro de 2023): 25. http://dx.doi.org/10.9753/icce.v37.sediment.25.
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Sediment deprivation, hydrologic alteration, subsidence, sea level rise, and saltwater intrusion have been causing significant land loss in coastal Louisiana. Breton Sound combined with the nearby Barataria Bay, and Mississippi River Delta have lost approximately 1800 square kilometers (or 447,000 acres) of land, representing one of the highest land loss rates in the world since the 1930s when the Mississippi River was leveed. To address this problem, the Coastal Protection and Restoration Authority (CPRA) initiated several sediment diversion projects in the Lower Mississippi River (LMR). The Mid- Breton Sediment Diversion (MBrSD) project is one of the costal restoration projects proposed to restore natural processes in Breton Sound, which can strategically reestablish hydrologic flows, carry land-building sediments, nourish marshes and sustain land.
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Everett, Thomas, Arpit Agarwal, Joshua Carter e Kazi Sadid. "INFLUENCE OF SALINITY WEDGE ON FLOW AND SEDIMENT DIVERSION THROUGH A COMPLEX DELTAIC SYSTEM". Coastal Engineering Proceedings, n.º 37 (2 de outubro de 2023): 150. http://dx.doi.org/10.9753/icce.v37.management.150.
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The Bird’s Foot Delta (BFD) is located at the confluence of the Mississippi River and the Gulf of Mexico in southeast Louisiana, USA. It is a 521,000-acre delta located around the three main distributaries (Southwest Pass, South Pass, and Pass-a-Loutre) off the terminal end (Head of Passes) of the Mississippi River. Here, the delta is a highly productive ecosystem that serves as a refuge for migratory birds, harbors fisheries, and acts as defense mechanism against storm surge for the city of New Orleans. Over the past several decades, the wetlands of the eastern BFD have experienced severe degradation. The primary cause of wetland loss in this area is the combination of relative sea level rise (RSLR) and decreased hydrologic connection to the Mississippi River, which results in insufficient sediment deposition and increased salinity. The BFD restoration project proposes to restore the hydrology and improve the freshwater and sediment delivery to the Eastern Bird’s Foot Delta through dredging some combination of the three largest distributaries south of Head of Passes (HOP). To inform restoration efforts, Mott MacDonald (MM) performed extensive modeling efforts to evaluate the influence of salt wedge on hydraulic and morphological patterns across the BFD.
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Smith, M., e S. J. Bentley. "Sediment capture in flood plains of the Mississippi River: A case study in Cat Island National Wildlife Refuge, Louisiana". Proceedings of the International Association of Hydrological Sciences 367 (3 de março de 2015): 442–46. http://dx.doi.org/10.5194/piahs-367-442-2015.
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Abstract. To plan restoration of the Mississippi River Delta, it is imperative to know how much sediment the Mississippi River currently provides. Recent research has demonstrated that between Tarbert Landing and St Francisville on the Mississippi, as much as 67 million metric tons (Mt) per year is lost from river transport, of which ~16 Mt is muddy suspended sediment. So where does this sediment go? Two pathways for loss have been proposed: riverbed storage, and overbank deposition in regions that lack manmade levées. Cat Island National Wildlife Refuge, on the unleveed Mississippi River east bank near St Francisville, Louisiana, consists of undisturbed bottomland forest that is inundated most years by river flooding. To determine fluvial sediment accumulation rates (SAR) from flooding, pushcores 40–50 cm long were collected then dated by Pb-210 and Cs-137 geochronology. Preliminary data suggests that muddy sediment accumulation is 10–13% of muddy suspended sediment lost from river transport along this river reach.
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Kemp, G. Paul, Elizabeth C. McDade, John W. Day, Robert R. Lane, Nancye H. Dawers e Jason N. Day. "Recovery and Restoration of Biloxi Marsh in the Mississippi River Delta". Water 13, n.º 22 (10 de novembro de 2021): 3179. http://dx.doi.org/10.3390/w13223179.
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The State of Louisiana is leading an integrated wetland restoration and flood risk reduction program in the Mississippi River Delta. East of New Orleans, Biloxi Marsh, a ~1700 km2 peninsula jutting 60 km north toward the State of Mississippi is one of few Delta wetland tracts well positioned to dissipate hurricane surge and waves threatening the city’s newly rebuilt hurricane flood defenses. Both its location on the eastern margin of the Delta, and its genesis as the geologic core of the shallow water St. Bernard/Terre aux Boeuf sub-delta, which was the primary Mississippi outlet for almost 2000 years, make Biloxi Marsh attractive for restoration, now that the Mississippi River Gulf Outlet deep-draft ship channel has been dammed, and 50 years of impacts from construction and operation have abated. Now, the cascade of ecosystem damage it caused can be reversed or offset by restoration projects that leverage natural recovery and increased access to suspended sediment from the Mississippi River. Biloxi Marsh is (1) geologically stable, (2) benefiting from increased input of river sediment, and (3) could be restored to sustainability earlier and for a longer period than most of the rest of the submerging Mississippi Delta. The focus of this review is on the Biloxi Marsh, but it also provides a template for regional studies, including analysis of 2D and 3D seismic and other energy industry data to explore why existing marshes that look similar on the ground or from the air may respond to restoration measures with different levels of success. Properties of inherent durability and resilience can be exploited in restoration project selection, sequencing and expenditure. Issues encountered and investigative methods applied in the Biloxi Marsh are likely to resonate across initiatives now contemplated to sustain valuable river deltas worldwide.
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Hijma, Marc P., Zhixiong Shen, Torbjörn E. Törnqvist e Barbara Mauz. "Late Holocene evolution of a coupled, mud-dominated delta plain–chenier plain system, coastal Louisiana, USA". Earth Surface Dynamics 5, n.º 4 (2 de novembro de 2017): 689–710. http://dx.doi.org/10.5194/esurf-5-689-2017.
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Abstract. Major deltas and their adjacent coastal plains are commonly linked by means of coast-parallel fluxes of water, sediment, and nutrients. Observations of the evolution of these interlinked systems over centennial to millennial timescales are essential to understand the interaction between point sources of sediment discharge (i.e. deltaic distributaries) and adjacent coastal plains across large spatial (i.e. hundreds of kilometres) scales. This information is needed to constrain future generations of numerical models to predict coastal evolution in relation to climate change and other human activities. Here we examine the coastal plain (Chenier Plain, CP) adjacent to the Mississippi River delta, one of the world's largest deltas. We use a refined chronology based on 22 new optically stimulated luminescence and 22 new radiocarbon ages to test the hypothesis that cyclic Mississippi subdelta shifting has influenced the evolution of the adjacent CP. We show that over the past 3 kyr, accumulation rates in the CP were generally 0–1 Mt yr−1. However, between 1.2 and 0.5 ka, when the Mississippi River shifted to a position more proximal to the CP, these rates increased to 2.9 ±1.1 Mt yr−1 or 0.5–1.5 % of the total sediment load of the Mississippi River. We conclude that CP evolution during the past 3 kyr was partly a direct consequence of shifting subdeltas, in addition to changing regional sediment sources and modest rates of relative sea-level (RSL) rise. The RSL history of the CP during this time period was constrained by new limiting data points from the base of overwash deposits associated with the cheniers. These findings have implications for Mississippi River sediment diversions that are currently being planned to restore portions of this vulnerable coast. Only if such diversions are located in the western portion of the Mississippi Delta plain could they potentially contribute to sustaining the CP shoreline. Our findings highlight the importance of a better understanding of mud-dominated shorelines that are often associated with major deltas, in light of the enormous investments in coastal management and restoration that will likely be made around the globe, now and especially later during this century.
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White, David A. "Vascular plant community development on mudflats in the Mississippi River delta, Louisiana, USA". Aquatic Botany 45, n.º 2-3 (abril de 1993): 171–94. http://dx.doi.org/10.1016/0304-3770(93)90020-w.
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Kil, Bumjun, Jerry D. Wiggert e Stephan D. Howden. "Evidence That an Optical Tail in the Gulf of Mexico After Tropical Cyclone Isaac was the Result of Offshore Advection of Coastal Water". Marine Technology Society Journal 48, n.º 4 (1 de julho de 2014): 27–35. http://dx.doi.org/10.4031/mtsj.48.4.4.
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AbstractThis study investigates the hypothesis of Acker's Web report in 2013 that an optical tail of high chlorophyll a, observed in the open Gulf of Mexico (GoM) approximately 2 weeks after tropical storm Isaac made landfall in coastal Louisiana, was due to advection of outflowing Mississippi River related with the mesoscale eddy field in the open GoM. By using available in situ data and data from multiple satellites, strong evidence was found to support Acker's hypothesis. Drifting buoy, remotely sensed sea surface salinity, and surface geostrophic current data were used to show that low-salinity water (LSW) was indeed associated with the optical tail. Remotely sensed colored dissolved organic matter indicated that the LSW was of coastal origin, and satellite-observed rain rate indicated that this LSW in the optical tail was not due to local precipitation. The path of freshwater from the Mississippi River Delta to the region offshore in the optical tail was shown to be similar to a simulated trajectory estimated by surface geostrophic currents; likewise, the drifting buoys deployed near the shelf break offshore of the Mississippi River Delta prior to the peak in discharge.
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Autin, Whitney J. "Influences of Relative Sea-Level Rise and Mississippi River Delta Plain Evolution on the Holocene Middle Amite River, Southeastern Louisiana". Quaternary Research 39, n.º 1 (janeiro de 1993): 68–74. http://dx.doi.org/10.1006/qres.1993.1008.
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AbstractThe Holocene geomorphic history of southeastern Louisiana's middle Amite River is recorded in the stratigraphy of three alloformations, identified in decreasing age as the Watson (WAT), Denham Springs (DS), and Magnolia Bridge (MAG). The WAT meander belt formed by at least 9000 yr B.P., when sea level was lower and the Amite River was tributary to a larger ancestral drainage basin. The DS became an active meander belt by at least 3000 yr B.P., in response to relative sea-level rise and eastward progradation of the Mississippi River delta plain. The MAG developed its meander belt, in part, during the European settlement of the drainage basin, and is now attempting to adjust to modern anthropogenic influences. Geomorphic influences on the middle Amite River floodplain have temporal and spatial components that induce regional- and local-scale effects. Regional extrinsic influences caused meander belt avulsion that produced alloformations. However, local influences produced intrinsic geomorphic thresholds that modified channel morphology within a meander belt but did not induce alloformation development. Base-level influences of the relative sea-level rise and the Mississippi River delta plain were so dominant that the effects of possible climate change were not recognized in the Holocene Amite River system.
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Yao, Qiang, Marcelo Cancela Lisboa Cohen, Kam-biu Liu, Adriana Vivan de Souza e Erika Rodrigues. "Nature versus Humans in Coastal Environmental Change: Assessing the Impacts of Hurricanes Zeta and Ida in the Context of Beach Nourishment Projects in the Mississippi River Delta". Remote Sensing 14, n.º 11 (28 de maio de 2022): 2598. http://dx.doi.org/10.3390/rs14112598.
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Hurricanes are one of the most devastating earth surface processes. In 2020 and 2021, Hurricanes Zeta and Ida pounded the Mississippi River Delta in two consecutive years, devastated South Louisiana, and raised tremendous concerns for scientists and stakeholders around the world. This study presents a high-resolution spatial-temporal analysis incorporating planialtimetric data acquired via LIDAR, drone, and satellite to investigate the shoreline dynamics near Port Fourchon, Louisiana, the eye of Ida at landfall, before and after the beach nourishment project and recent hurricane landfalls. The remote sensing analysis shows that the volume of the ~2 km studied beachfront was reduced by 240,858 m3 after consecutive landfalls of Hurricanes Zeta and Ida in 2020 and 2021, while 82,915 m3 of overwash fans were transported to the backbarrier areas. Overall, the studied beach front lost almost 40% of its volume in 2019, while the average dune crest height was reduced by over 1 m and the shoreline retreated ~60 m after the two hurricane strikes. Our spatial-temporal dataset suggests that the Louisiana Coastal Protection and Restoration Authority’s (CPRA’s) beach nourishment effort successfully stabilized the beach barrier at Port Fourchon during the hurricane-quiescent years but was not adequate to protect the shoreline at the Mississippi River Delta from intense hurricane landfalls. Our study supports the conclusion that, in the absence of further human intervention, Bay Champagne will likely disappear completely into the Gulf of Mexico within the next 40 years.
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Stephens, Shane A., Michael A. Dance, Michelle Zapp Sluis, Richard J. Kline, Matthew K. Streich, Gregory W. Stunz, Aaron J. Adams, R. J. David Wells e Jay R. Rooker. "Spatial distribution and movement of Atlantic tarpon (Megalops atlanticus) in the northern Gulf of Mexico". PLOS ONE 19, n.º 3 (7 de março de 2024): e0298394. http://dx.doi.org/10.1371/journal.pone.0298394.
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Atlantic tarpon (Megalops atlanticus) are capable of long-distance migrations (hundreds of kilometers) but also exhibit resident behaviors in estuarine and coastal habitats. The aim of this study was to characterize the spatial distribution of juvenile tarpon and identify migration pathways of adult tarpon in the northern Gulf of Mexico. Spatial distribution of juvenile tarpon was investigated using gillnet data collected by Texas Parks and Wildlife Department (TPWD) over the past four decades. Generalized additive models (GAMs) indicated that salinity and water temperature played a significant role in tarpon presence, with tarpon occurrences peaking in the fall and increasing over the past four decades in this region. Adult tarpon caught off Texas (n = 40) and Louisiana (n = 4) were tagged with acoustic transmitters to characterize spatial and temporal trends in their movements and migrations. Of the 44 acoustic transmitters deployed, 18 of the individuals were detected (n = 16 west of the Mississippi River Delta and n = 2 east of the Mississippi River Delta). Tarpon tagged west of the Mississippi River Delta off Texas migrated south in the fall and winter into areas of south Texas and potentially into Mexico, while individuals tagged east of the delta migrated into Florida during the same time period, suggesting the presence of two unique migratory contingents or subpopulations in this region. An improved understanding of the habitat requirements and migratory patterns of tarpon inhabiting the Gulf of Mexico is critically needed by resource managers to assess the vulnerability of each contingent to fishing pressure, and this information will guide multi-state and multi-national conservation efforts to rebuild and sustain tarpon populations.
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Niebling, William, Jonathan Baker, Laila Kasuri, Sarah Katz e Kim Smet. "Challenge and response in the Mississippi River Basin". Water Policy 16, S1 (1 de março de 2014): 87–116. http://dx.doi.org/10.2166/wp.2014.005.
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This paper discusses the historic and contemporary challenges in the management of the lower Mississippi River Basin, and describes the evolving role of the federal government in addressing these challenges. In the early eighteenth century, the federal government was responsible for maintaining a navigable channel. After repeated calls by states for federal assistance with flood control and a devastating flood in 1927, the federal government additionally became the primary body responsible for protecting the Delta from floods. Although the resulting flood control system provided greater protection, it also brought new challenges, such as an increasingly large hypoxic zone in the Gulf of Mexico, land subsidence in southern Louisiana and water quality issues. The confluence of these environmental concerns and changing national values have once again broadened the scope of federal responsibility to include environmental management and ecosystem restoration, along with its original involvement in navigation and flood control. This triad of responsibility carries with it often-competing objectives that must be balanced within legal and institutional constraints, most notably a deficit of available funding for inland waterway projects and what appears to be a lack of political will for continued investment in the maintenance of existing and development of new projects.
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Dietrich, J. C., S. Bunya, J. J. Westerink, B. A. Ebersole, J. M. Smith, J. H. Atkinson, R. Jensen et al. "A High-Resolution Coupled Riverine Flow, Tide, Wind, Wind Wave, and Storm Surge Model for Southern Louisiana and Mississippi. Part II: Synoptic Description and Analysis of Hurricanes Katrina and Rita". Monthly Weather Review 138, n.º 2 (1 de fevereiro de 2010): 378–404. http://dx.doi.org/10.1175/2009mwr2907.1.
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Abstract Hurricanes Katrina and Rita were powerful storms that impacted southern Louisiana and Mississippi during the 2005 hurricane season. In Part I, the authors describe and validate a high-resolution coupled riverine flow, tide, wind, wave, and storm surge model for this region. Herein, the model is used to examine the evolution of these hurricanes in more detail. Synoptic histories show how storm tracks, winds, and waves interacted with the topography, the protruding Mississippi River delta, east–west shorelines, manmade structures, and low-lying marshes to develop and propagate storm surge. Perturbations of the model, in which the waves are not included, show the proportional importance of the wave radiation stress gradient induced setup.
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Hu, Kelin, Ehab Meselhe e J. Andrew Nyman. "The Effect of Phragmites australis Dieback on Channel Sedimentation in the Mississippi River Delta: A Conceptual Modeling Study". Water 13, n.º 10 (18 de maio de 2021): 1407. http://dx.doi.org/10.3390/w13101407.
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Phragmites australis is a globally distributed wetland plant. At the mouth of the Mississippi River, P. australis on natural levees of the network of distributary channels appears to increase the flow in the deep draft navigation channel, which, in turn, may reduce the sedimentation and benefit the navigation dredging. For several years, P. australis has been dying in the Mississippi River’s Bird’s Foot Delta, which appears to be shortening the distributary channels and increasing the lateral flow from the remaining portions. A conceptual model based on D-FLOW FM was applied to calculate channel sedimentation in a series of idealized deltaic systems to predict the consequences of P. australis dieback and other factors that diminish the delta complexity, such as sea-level rise and subsidence, on sedimentation in the distributary channels. Channel complexity in each system, which was quantified with an index ranging from 0 to 10 that we developed. Model results indicate that sedimentation was insensitive to the channel complexity in simple deltas but was sensitive to the channel complexity in complex deltas, such as the current Mississippi River Delta with extensive P. australis. Channel sedimentation remains stable from 0 until the channel complexity index reaches 6. In more complex deltas, the sedimentation decreases rapidly as the channel complexity increases. The sedimentation is also affected by waves, river discharge, sediment concentration, grain sizes, and bed level. River managers in Louisiana may benefit from new models based on bathymetric data throughout the Bird’s Foot Delta; data on the effects of the P. australis belowground biomass on bank erodibility across a range of current velocities; and data on the effects of P. australis stem density, diameter, and height on the lateral flow across a range of river stages and tidal stages to help them decide how much to respond to Phragmites dieback. Options include increased navigation dredging, increased restoration of the channel complexity via a thin layer of sediment deposition on natural levees and the planting of more salt-tolerant vegetation on natural levees.
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Khalil, S. M., e A. M. Freeman. "Challenges of ecosystem restoration in Louisiana – availability of sediment and its management". Proceedings of the International Association of Hydrological Sciences 367 (3 de março de 2015): 455–62. http://dx.doi.org/10.5194/piahs-367-455-2015.
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Abstract. Human intervention has impaired the Mississippi River’s ability to deliver sediment to its delta wetlands, and as a consequence acute land loss in coastal Louisiana has resulted in an unprecedented ecocatastrophe. To mitigate this degradation, an unparalleled restoration effort is underway. For this effort to be successful and sustainable, various sediment input mechanisms must be integrated, including: building appropriate sediment-diversions; beneficially using the millions of cubic metres of sediment dredged annually from navigational channels; harvesting deposits of sand and suitable sediment from the river and offshore; and related sediment management activities that are compatible with other uses of the river. A comprehensive sediment management plan has been developed to identify and delineate potential sediment sources for restoration, and to provide a framework for managing sediment resources wisely, cost effectively, and in a systematic manner. The Louisiana Sediment Management Plan provides regional strategies for improved comprehensive management of Louisiana's limited sediment resources.
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Pasquier, Michael. "Remembering and Forgetting the Past on the Mississippi River: Toward an Environmental History of Catholicism". Catholic Historical Review 110, n.º 2 (março de 2024): vi—261. http://dx.doi.org/10.1353/cat.2024.a927994.
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Abstract: After the flood of 1927, the US government decided to master the Mississippi River. Nowhere was this state-sponsored determination more evident than in the lower Mississippi River delta. An historical examination of a cluster of Catholic churches in Pointe Coupée Parish, Louisiana, permits some understanding of how physical and material alterations to landscapes are not easily traced, especially when we consider the temporal and spatial scales of change to the Mississippi over the last one hundred years. In that time, Catholics of Pointe Coupée Parish managed to retain, erase, and revise aspects of their bonds to a river once central to the lives of their ancestors. This is not at all surprising, as the fallibility of memory is made apparent every time we try to tell stories about our pasts. Pointe Coupée Parish is one site where we can explore how alterations to a landscape have an impact not only on the trajectory of a Catholic community's future, but also on access to its past. Absences of memory in the living, combined with the erasure of material remains in modified landscapes, challenge us to consider how we might account for the relationship between Catholicism and the built environment throughout American history.
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Ryu, Junghyung, Kam-biu Liu, Thomas A. Bianchette e Terry McCloskey. "Identifying forcing agents of environmental change and ecological response on the Mississippi River Delta, Southeastern Louisiana". Science of The Total Environment 794 (novembro de 2021): 148730. http://dx.doi.org/10.1016/j.scitotenv.2021.148730.
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Mehta, Jayur Madhusudan, e Elizabeth L. Chamberlain. "Mound Construction and Site Selection in the Lafourche Subdelta of the Mississippi River Delta, Louisiana, USA". Journal of Island and Coastal Archaeology 14, n.º 4 (18 de maio de 2018): 453–78. http://dx.doi.org/10.1080/15564894.2018.1458764.
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White, David A., e Jenneke M. Visser. "Twenty-Eight Years of Plant Community Development and Dynamics in the Balize Mississippi River Delta, Louisiana, USA". Water 15, n.º 19 (3 de outubro de 2023): 3481. http://dx.doi.org/10.3390/w15193481.
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Deltaic landscapes go through cycles of birth, growth, decline, and death governed by intertwined geological, biological, and ecological processes. In this study, we tracked deltaic lobes in the Balize Mississippi River Delta, Louisiana, USA, over 28 years (1984–2012). Hydrologic and geomorphic patterns as well as sustained patterns of wetland plant richness, diversity, and biomass are described. Plant diversity and biomass were modeled by nMDS ordination. Taxa (53) were harvested and dried (116,706 g) from 965 (0.25 m2) plots and divided into three groups: I. four foundation species, corresponding to 78.9% of the total harvest; II. nine pioneer species, corresponding to 13.6% of the total harvest; and III. all other taxa, corresponding to 7.5% of the total harvest (eight miscellaneous grasses, eight miscellaneous sedges, and twenty-four miscellaneous herbs). Autogenic/allogenic processes (sedimentation, subsidence, plant colonization, and succession events) affected composition and biomass. Eleven important species were identified. Taxon richness increased on mudflats during primary succession (fifteen to twenty-five taxa per site), then declined to fewer than five taxa per site. The niche space theory explained patterns of community change, with a similar total biomass/yr (~500 g/m2/yr) at all study sites. Quantile regression analyses showed that the water quality and quantity of the Mississippi River influenced biomass, especially in springtime waters. Stochastic events (storms, herbivory, salt burn, and flood pulses) impacted biomass. Long-term studies like this are required in a future of climate unknowns.
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Jun Xu, Y. "Rethinking the Mississippi River diversion for effective capture of riverine sediments". Proceedings of the International Association of Hydrological Sciences 367 (3 de março de 2015): 463–70. http://dx.doi.org/10.5194/piahs-367-463-2015.
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Abstract. Many river deltas in the world are vibrant economic regions, serving as transportation hubs, population centres, and commercial hotspots. However, today, many of these deltaic areas face a tremendous challenge with land loss due to a number of factors, such as reduced riverine sediment supply, coastal land erosion, subsidence, and sea level rise. The development of the Mississippi River Deltaic Plain (MRDP) in southeast Louisiana, USA, over the past century is a good example. Since 1932, approximately 4877 km2 of the coastal land of MRDP has become submerged. The lower Mississippi River main channel entering the Gulf of Mexico has become an isolated waterway with both sides losing land. In contrast, large open water areas in the Mississippi River’s distributary basin, the Atchafalaya River basin, have been silted up over the past century, and the river mouth has developed a prograding delta feature at its two outlets to the Gulf of Mexico. The retrospective analysis of this paper makes it clear that the main cause of the land loss in the MRDP is not the decline of riverine sediment, but the disconnection of the sediment sources from the natural flood plains. Future sediment management efforts in the MRDP should focus on restoring the natural connection of riverine sediment supplies with flood plains, rather than solely using channelized river diversion. This could be achieved through controlled overbank flooding (COF) and artificial floods in conjunction with the use of a hydrograph-based sediment availability assessment.
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Laurent, A., K. Fennel, J. Hu e R. Hetland. "Simulating the effects of phosphorus limitation in the Mississippi and Atchafalaya River plumes". Biogeosciences Discussions 9, n.º 5 (14 de maio de 2012): 5625–57. http://dx.doi.org/10.5194/bgd-9-5625-2012.
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Abstract. The continental shelf of the northern Gulf of Mexico receives high dissolved inorganic nitrogen and phosphorus loads from the Mississippi and Atchafalaya rivers. The nutrient load results in high primary production in the river plumes and contributes to the development of hypoxia on the Texas-Louisiana shelf in summer. While phytoplankton growth is considered to be typically nitrogen-limited, phosphorus limitation has been observed in this region during periods of peak river discharge in spring and early summer. Here we investigate the presence, spatio-temporal distribution and implications of phosphorus limitation in the plume region using a circulation model of the northern Gulf of Mexico coupled to a multi-nutrient ecosystem model. Results from a 7 yr simulation (2001–2007) compare well with available observations and suggest that phosphorus limitation develops every year between the Mississippi and Atchafalaya deltas. Model simulations show that phosphorus limitation results in a delay and westward shift of a fraction of river-stimulated primary production. The consequence is a reduced flux of particulate organic matter to the sediment near the Mississippi delta, but enhanced fluxes westward in the Atchafalaya and far-field regions. Two discharge scenarios with altered river phosphate concentrations (±50 %) reveal a significant variation (±40 % in July) in the spatial extent of phosphorus limitation with changes in phosphate load.
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Laurent, A., K. Fennel, J. Hu e R. Hetland. "Simulating the effects of phosphorus limitation in the Mississippi and Atchafalaya River plumes". Biogeosciences 9, n.º 11 (22 de novembro de 2012): 4707–23. http://dx.doi.org/10.5194/bg-9-4707-2012.
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Abstract. The continental shelf of the northern Gulf of Mexico receives high dissolved inorganic nitrogen and phosphorus loads from the Mississippi and Atchafalaya rivers. The nutrient load results in high primary production in the river plumes and contributes to the development of hypoxia on the Louisiana shelf in summer. While phytoplankton growth is considered to be typically nitrogen-limited in marine waters, phosphorus limitation has been observed in this region during periods of peak river discharge in spring and early summer. Here we investigate the presence, spatio-temporal distribution and implications of phosphorus limitation in the plume region using a circulation model of the northern Gulf of Mexico coupled to a multi-nutrient ecosystem model. Results from a 7-yr simulation (2001–2007) compare well with several sources of observations and suggest that phosphorus limitation develops every year between the Mississippi and Atchafalaya deltas. Model simulations show that phosphorus limitation results in a delay and westward shift of a fraction of river-stimulated primary production. The consequence is a reduced flux of particulate organic matter to the sediment near the Mississippi delta, but slightly enhanced fluxes west of Atchafalaya Bay. Simulations with altered river phosphate concentrations (±50%) show that significant variation in the spatial extent of phosphorus limitation (±40% in July) results from changes in phosphate load.
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Mitsch, W. J. "Applying science to conservation and restoration of the world's wetlands". Water Science and Technology 51, n.º 8 (1 de abril de 2005): 13–26. http://dx.doi.org/10.2166/wst.2005.0215.
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The world has an estimated 7 to 9 million km2 of wetlands which can be defined through their hydrology, physiochemical environment, and biota. Many human cultures have lived in harmony with wetland environments for centuries. Many others have not, resulting in drainage or severe impact of wetlands throughout the world. Conservation of wetlands needs to be a priority for the cultural and ecological values they provide. But a more optimistic note is that large-scale restoration and re-creation of wetlands and riverine systems is beginning to happen throughout the world through ecological engineering. Examples of large-scale wetland restoration projects are presented for Delaware Bay, the Skjern River (Denmark), Florida Everglades, Louisiana Delta, the Mississippi River Basin, and the Mesopotamian Marshlands of Iraq.
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Day, John W., Bin Li, Brian D. Marx, Dongran Zhao e Robert R. Lane. "Multivariate Analyses of Water Quality Dynamics Over Four Decades in the Barataria Basin, Mississippi Delta". Water 12, n.º 11 (10 de novembro de 2020): 3143. http://dx.doi.org/10.3390/w12113143.
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Here we examine a combined dataset of water quality dynamics in the Barataria Basin, Louisiana based on transect studies from 1977 to 1978 (Seaton) and from 1994 to 2016. The Davis Pond river diversion into Lake Cataouatche began discharging Mississippi River water into the mid-basin in 2005, and so the later dataset was divided in Pre- and Post-diversion periods. The stations from these three datasets (Seaton, Pre- and Post-diversion) were combined into eleven station groupings for statistical analysis that included ANOVA and principal component analysis. In addition, Trophic State Index (TSI) scores were calculated for each grouping during the three time periods. Lake Cataouatche changed the most with the opening of the Davis Pond river diversion, becoming clearer and less eutrophic with addition of river water, which passed through a large wetland area where sediments were retained before entering the lake. The TSI results for the Seaton re-analysis were very similar to the original analysis and to that of the Pre- and Post-diversion datasets, indicating that the trophic status of the basin waters has remained relatively unchanged. The upper-basin has remained eutrophic with degraded water quality while the lower-basin has remained more mesotrophic without significant water quality deterioration. A main cause of water quality deterioration is agricultural runoff and pervasive hydrologic alteration that bypasses wetlands and causes most runoff to flow directly into water bodies.
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Lam, Nina, Y. Xu, Kam-biu Liu, David Dismukes, Margaret Reams, R. Pace, Yi Qiang et al. "Understanding the Mississippi River Delta as a Coupled Natural-Human System: Research Methods, Challenges, and Prospects". Water 10, n.º 8 (8 de agosto de 2018): 1054. http://dx.doi.org/10.3390/w10081054.
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A pressing question facing the Mississippi River Delta (MRD), like many deltaic communities around the world, is: Will the system be sustainable in the future given the threats of sea level rise, land loss, natural disasters, and depleting natural resources? An integrated coastal modeling framework that incorporates both the natural and human components of these communities, and their interactions with both pulse and press stressors, is needed to help improve our understanding of coastal resilience. However, studying the coastal communities using a coupled natural-human system (CNH) approach is difficult. This paper presents a CNH modeling framework to analyze coastal resilience. We first describe such a CNH modeling framework through a case study of the Lower Mississippi River Delta in coastal Louisiana, USA. Persistent land loss and associated population decrease in the study region, a result of interplays between human and natural factors, are a serious threat to the sustainability of the region. Then, the paper describes the methods and findings of three studies on how community resilience of the MRD system is measured, how land loss is modeled using an artificial neural network-cellular automata approach, and how a system dynamic modeling approach is used to simulate population change in the region. The paper concludes by highlighting lessons learned from these studies and suggesting the path forward for analysis of coupled natural-human systems.
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Doser, L. S., R. E. Ferrell, F. J. Longstaffe e P. M. Walthall. "Fluid flow through clayey soils: stable isotope and mineralogical evidence". Clay Minerals 33, n.º 1 (março de 1998): 43–49. http://dx.doi.org/10.1180/000985598545417.
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AbstractThe evaluation of clays as barriers to fluid movement can be improved by geochemical methods that provide ways to examine the reactivity and weathering of minerals in soils and sediments. X-ray radiography, X-ray powder diffraction, and stable isotope geochemistry provide new data from field locations in the Mississippi River Delta of Louisiana indicating that the clays are not effective barriers to the vertical migration of fluids in the shallow subsurface. Systematic changes in the mineral assemblages, the soil structure and the δD and δ18O values of time clay fractions can best be explained by an alteration sequence produced as the originally smectiterich clay mineral assemblage was kaolinized by percolating groundwater.
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Neill, Christopher, e Linda A. Deegan. "The Effect of Mississippi River Delta Lobe Development on the Habitat Composition and Diversity of Louisiana Coastal Wetlands". American Midland Naturalist 116, n.º 2 (outubro de 1986): 296. http://dx.doi.org/10.2307/2425737.
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He, Songjie, Kanchan Maiti, Neha Ghaisas, Kiran Upreti e Victor H. Rivera-Monroy. "Potential methane production in oligohaline wetlands undergoing erosion and accretion in the Mississippi River Delta Plain, Louisiana, USA". Science of The Total Environment 875 (junho de 2023): 162685. http://dx.doi.org/10.1016/j.scitotenv.2023.162685.
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Fennel, K., R. Hetland, Y. Feng e S. DiMarco. "A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability". Biogeosciences Discussions 8, n.º 1 (7 de janeiro de 2011): 121–56. http://dx.doi.org/10.5194/bgd-8-121-2011.
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Abstract. The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer. The mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. We present results from a realistic, 3-dimensional, physical-biological model that includes the processes thought to be of first order importance to hypoxia formation and demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input. We find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes. We hypothesize that increased retention of river water in high discharge years explains this phenomenon.
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Craddock, W. H., e A. R. C. Kylander-Clark. "U-Pb ages of detrital zircons from the Tertiary Mississippi River Delta in central Louisiana: Insights into sediment provenance". Geosphere 9, n.º 6 (13 de novembro de 2013): 1832–51. http://dx.doi.org/10.1130/ges00917.1.
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Quintana-Ashwell, Nicolas, Drew Gholson, Gurpreet Kaur, Gurbir Singh, Joseph Massey, L. Jason Krutz, Christopher G. Henry, Trey Cooke, Michele Reba e Martin A. Locke. "Irrigation Water Management Tools and Alternative Irrigation Sources Trends and Perceptions by Farmers from the Delta Regions of the Lower Mississippi River Basin in South Central USA". Agronomy 12, n.º 4 (7 de abril de 2022): 894. http://dx.doi.org/10.3390/agronomy12040894.
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This article describes the opinions and perceptions of farmers on water management tools that conserve groundwater and on alternative sources of water for irrigation. The analysis is based on a survey of producers (N=466) across the Lower Mississippi River Basin (LMRB) areas of Arkansas, Louisiana, Mississippi, and Missouri. Summary statistics of practice usage across the region and for each state are presented. A Poisson count model is applied to the data to identify factors that influence the number of groundwater-conserving practices employed. The number of irrigated acres, years of farming, annual income level, perception of groundwater problems, and participation in conservation programs have statistically significant association with the number of practices employed. Years of farming experience is the only factor negatively associated with the number of practices employed, while participation in conservation programs has the largest magnitude effect on that number. These results provide evidence that sponsored conservation programs increase the number of conservation practices adopted by farmers. This insight is useful for producer collectives, policy makers, and program managers to design and target of conservation programs across the LMRB.
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Day, John, H. Clark, Chandong Chang, Rachael Hunter e Charles Norman. "Life Cycle of Oil and Gas Fields in the Mississippi River Delta: A Review". Water 12, n.º 5 (23 de maio de 2020): 1492. http://dx.doi.org/10.3390/w12051492.
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Oil and gas (O&G) activity has been pervasive in the Mississippi River Delta (MRD). Here we review the life cycle of O&G fields in the MRD focusing on the production history and resulting environmental impacts and show how cumulative impacts affect coastal ecosystems. Individual fields can last 40–60 years and most wells are in the final stages of production. Production increased rapidly reaching a peak around 1970 and then declined. Produced water lagged O&G and was generally higher during declining O&G production, making up about 70% of total liquids. Much of the wetland loss in the delta is associated with O&G activities. These have contributed in three major ways to wetland loss including alteration of surface hydrology, induced subsidence due to fluids removal and fault activation, and toxic stress due to spilled oil and produced water. Changes in surface hydrology are related to canal dredging and spoil placement. As canal density increases, the density of natural channels decreases. Interconnected canal networks often lead to saltwater intrusion. Spoil banks block natural overland flow affecting exchange of water, sediments, chemicals, and organisms. Lower wetland productivity and reduced sediment input leads to enhanced surficial subsidence. Spoil banks are not permanent but subside and compact over time and many spoil banks no longer have subaerial expression. Fluid withdrawal from O&G formations leads to induced subsidence and fault activation. Formation pore pressure decreases, which lowers the lateral confining stress acting in the formation due to poroelastic coupling between pore pressure and stress. This promotes normal faulting in an extensional geological environment like the MRD, which causes surface subsidence in the vicinity of the faults. Induced reservoir compaction results in a reduction of reservoir thickness. Induced subsidence occurs in two phases especially when production rate is high. The first phase is compaction of the reservoir itself while the second phase is caused by a slow drainage of pore pressure in bounding shales that induces time-delayed subsidence associated with shale compaction. This second phase can continue for decades, even after most O&G has been produced, resulting in subsidence over much of an oil field that can be greater than surface subsidence due to altered hydrology. Produced water is water brought to the surface during O&G extraction and an estimated 2 million barrels per day were discharged into Louisiana coastal wetlands and waters from nearly 700 sites. This water is a mixture of either liquid or gaseous hydrocarbons, high salinity (up to 300 ppt) water, dissolved and suspended solids such as sand or silt, and injected fluids and additives associated with exploration and production activities and it is toxic to many estuarine organisms including vegetation and fauna. Spilled oil has lethal and sub-lethal effects on a wide range of estuarine organisms. The cumulative effect of alterations in surface hydrology, induced subsidence, and toxins interact such that overall impacts are enhanced. Restoration of coastal wetlands degraded by O&G activities should be informed by these impacts.
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Fennel, K., R. Hetland, Y. Feng e S. DiMarco. "A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability". Biogeosciences 8, n.º 7 (13 de julho de 2011): 1881–99. http://dx.doi.org/10.5194/bg-8-1881-2011.
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Abstract. The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer, but the mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. Unraveling these interactions will have to rely on a combination of observations and models. Here we present results from a realistic, 3-dimensional, physical-biological model with focus on a quantification of nutrient-stimulated phytoplankton growth, its variability and the fate of this organic matter. We demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input, and find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes.
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Gordon, Bonnie J., e Stanislav Roudavski. "More-than-human Infrastructure for Just Resilience: Learning from, Working with, and Designing for Bald Cypress Trees (Taxodium distichum) in the Mississippi River Delta". Global Environment 14, n.º 3 (1 de setembro de 2021): 442–74. http://dx.doi.org/10.3197/ge.2021.140302.
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Humans design infrastructure for human needs, with limited regard for the needs of nonhumans such as animals and plants. Humans also often fail to recognise nonhuman lifeforms such as trees as fellow engineers designers, or architects, even though the contribution of trees to ecosystem services is well established and their right to justice ought to be recognised. Studies have shown that flood-control infrastructure near the Mississippi River inadvertently left Southern Louisiana more vulnerable to coastal threats. We examine this characteristic outcome and identify infrastructural injustices in multispecies communities. Based on theories in philosophy and design supported by historical analyses, we defend the proposals to extend 1) the understanding of resilience to include more-than-human communities; and 2) the notion of justice to include non-human stakeholders. The reframing in more-than-human terms is already under way in a variety of disciplines. However, these efforts rarely extend into considerations of practical design and have attracted criticism for insufficient engagement with historical processes and the accumulations of power and responsibility. To illustrate these injustices, we trace the history of bald cypress trees (Taxodium distichum) in the Mississippi River Delta and show how infrastructure impacted the trees. This analysis demonstrates that designs that do not consider the needs of vulnerable stakeholders can cause harm in multispecies communities. In response, we propose that humans can work to improve infrastructural resilience by including humans and nonhumans as collaborators.
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Horst, Toni, e Anne Moore. "Industrial Diversity, Economic Development, and Highway Investment in Louisiana". Transportation Research Record: Journal of the Transportation Research Board 1839, n.º 1 (janeiro de 2003): 136–41. http://dx.doi.org/10.3141/1839-15.
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Studies examining the link between transportation investment and economic development typically measure development by job and income gains or productivity growth. For some economies, however, stabilization or diversification of the existing economic base is a desired outcome that needs to be attained even as traditional development goals are targeted. This is particularly the case for the rural and persistently poor economies of the Mississippi River Delta region of the United States. Small populations and remoteness are especially acute, constraining the number and kind of employers who will locate or expand in these markets, limiting the job opportunities for residents, and perpetuating the out-migration of younger and better-educated workers. Using information from the Economic Development Highways Initiative that was directed by Congress and administered by the Federal Highway Administration, this study analyzes the linkage between highway investment and economic diversification in Louisiana to evaluate whether this type of investment can play a role in stabilizing these weak and deteriorating economies. Using two-digit employment data, a summary index of industrial diversity is calculated for each parish (county) in Louisiana for the period 1977 to 1997. This diversity index is then correlated with the type of road present in the parish-Interstate, divided highway, and major thoroughfare. Results indicate that highway quality is associated with industrial diversification, even controlling for the size of the economy.
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Tupitza, Jillian C., e Cassandra N. Glaspie. "Restored freshwater flow and estuarine benthic communities in the northern Gulf of Mexico: research trends and future needs". PeerJ 8 (21 de fevereiro de 2020): e8587. http://dx.doi.org/10.7717/peerj.8587.
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Restoring river connectivity to rebuild and sustain land is a promising restoration strategy in coastal areas experiencing rapid land loss, such as the Mississippi river delta. Results of these large-scale hydrologic changes are preliminary, and there exists limited empirical evidence regarding how benthic communities will respond, specifically in Barataria Bay and Breton Sound in southeast Louisiana. In this review, the body of existing research in this geographic region pertaining to the drivers of benthic community response that are related to restored freshwater flow and sediment deposition is examined. Overall trends include (1) potential displacement of some species down-estuary due to reduced salinities; (2) temporary lower diversity in areas closest to the inflow; (3) increased benthic production along the marsh edge, and in tidal bayous, as a result of nutrient loading; (4) more habitat coverage in the form of submerged aquatic vegetation; and (5) reduced predation pressure from large and/or salinity-restricted predators. These trends highlight opportunities for future research that should be conducted before large-scale hydrologic changes take place.
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Dietz, Marianne, Kam-biu Liu e Thomas Bianchette. "Hurricanes as a Major Driver of Coastal Erosion in the Mississippi River Delta: A Multi-Decadal Analysis of Shoreline Retreat Rates at Bay Champagne, Louisiana (USA)". Water 10, n.º 10 (19 de outubro de 2018): 1480. http://dx.doi.org/10.3390/w10101480.
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The Louisiana shoreline is rapidly retreating as a result of factors such as sea-level rise and land subsidence. The northern Gulf of Mexico coast is also a hotspot for hurricane landfalls, and several major storms have impacted this region in the past few decades. A section of the Louisiana (USA) coast that has one of the highest rates of shoreline retreat in North America is the Caminada-Moreau headland, located south of New Orleans. Bay Champagne is a coastal lake within the headland that provides a unique opportunity to investigate shoreline retreat and the coastal effects of hurricanes. In order to examine the influence of hurricanes on the rate of shoreline retreat, 35 years (1983–2018) of Landsat imagery was analyzed. During that period of time, the shoreline has retreated 292 m. The overall rate of shoreline retreat, prior to a beach re-nourishment project completed in 2014, was over 12 m per year. A period of high hurricane frequency (1998–2013) corresponds to an increased average shoreline retreat rate of >21 m per year. Coastal features created by multiple hurricanes that have impacted this site have persisted for several years. Bay Champagne has lost 48% of its surface area over the last 35 years as a result of long-term shoreline retreat. If shoreline retreat continues at the average rate, it is expected that Bay Champagne will disappear completely within the next 40 years.
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Yang, Mingzheng, Lei Zou, Heng Cai, Yi Qiang, Binbin Lin, Bing Zhou, Joynal Abedin e Debayan Mandal. "Spatial–Temporal Land Loss Modeling and Simulation in a Vulnerable Coast: A Case Study in Coastal Louisiana". Remote Sensing 14, n.º 4 (13 de fevereiro de 2022): 896. http://dx.doi.org/10.3390/rs14040896.
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Coastal areas serve as a vital interface between the land and sea or ocean and host about 40% of the world’s population, providing significant social, economic, and ecological functions. Meanwhile, the sea-level rise caused by climate change, along with coastal erosion and accretion, alters coastal landscapes profoundly, threatening coastal sustainability. For instance, the Mississippi River Delta in Louisiana is one of the most vulnerable coastal areas. It faces severe long-term land loss that has disrupted the regional ecosystem balance during the past few decades. There is an urgent need to understand the land loss mechanism in coastal Louisiana and identify areas prone to land loss in the future. This study modeled the current and predicted the future land loss and identified natural–human variables in the Louisiana Coastal Zone (LCZ) using remote sensing and machine-learning approaches. First, we analyzed the temporal and spatial land loss patterns from 2001 to 2016 in the study area. Second, logistic regression, extreme gradient boosting (XGBoost), and random forest models with 15 human and natural variables were carried out during each five-year and the fifteen-year period to delineate the short- and long-term land loss mechanisms. Finally, we simulated the land-loss probability in 2031 using the optimal model. The results indicate that land loss patterns in different parts change through time at an overall decelerating speed. The oil and gas well density and subsidence rate were the most significant land loss drivers during 2001–2016. The simulation shows that a total area of 180 km2 of land has over a 50% probability of turning to water from 2016 to 2031. This research offers valuable information for decision-makers and local communities to prepare for future land cover changes, reduce potential risks, and efficiently manage the land restoration in coastal Louisiana.
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Denbina, Michael, Marc Simard, Ernesto Rodriguez, Xiaoqing Wu, Albert Chen e Tamlin Pavelsky. "Mapping Water Surface Elevation and Slope in the Mississippi River Delta Using the AirSWOT Ka-Band Interferometric Synthetic Aperture Radar". Remote Sensing 11, n.º 23 (21 de novembro de 2019): 2739. http://dx.doi.org/10.3390/rs11232739.
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AirSWOT is an airborne Ka-band synthetic aperture radar, capable of mapping water surface elevation (WSE) and water surface slope (WSS) using single-pass interferometry. AirSWOT was designed as a calibration and validation instrument for the forthcoming Surface Water and Ocean Topography (SWOT) mission, an international spaceborne synthetic aperture radar mission planned for launch in 2022 which will enable global mapping of WSE and WSS. As an airborne instrument, capable of quickly repeating overflights, AirSWOT enables measurement of high frequency and fine scale hydrological processes encountered in coastal regions. In this paper, we use data collected by AirSWOT in the Mississippi River Delta and surrounding wetlands of coastal Louisiana, USA, to investigate the capabilities of Ka-band interferometry for mapping WSE and WSS in coastal marsh environments. We introduce a data-driven method to estimate the time-varying interferometric phase drift resulting from radar hardware response to environmental conditions. A system of linear equations based on AirSWOT measurements is solved for elevation bias and time-varying phase calibration parameters using weighted least squares. We observed AirSWOT WSE uncertainty of 12 cm RMS compared to in situ water level measurements when averaged over an area of 0.5 km 2 at incidence angles below 15 ∘ . At higher incidence angles, the observed AirSWOT elevation bias is possibly due to residual phase calibration errors or radar backscatter from vegetation. Elevation profiles along the Wax Lake Outlet river channel indicate AirSWOT can measure WSS over a 24 km distance with uncertainty below 0.3 cm/km, 8% of the true water surface slope as measured by in situ data. The data analysis and results presented in this paper demonstrate the potential of AirSWOT to measure water surface elevation and slope within highly dynamic and spatially complex coastal environments.
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Keddy, P. A., D. Campbell, T. McFalls, G. P. Shaffer, R. Moreau, C. Dranguet e R. Heleniak. "The Wetlands of Lakes Pontchartrain and Maurepas: Past, Present and Future". Environmental Reviews 15, NA (dezembro de 2007): 43–77. http://dx.doi.org/10.1139/a06-008.
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One of the largest wetlands along the Gulf Coast of North America (ca. 150 000 ha) occurs around the shorelines of Lake Pontchartrain and Lake Maurepas in southeastern Louisiana, just north and west of New Orleans. We provide an introduction to the environmental history of the marshes and swamps in the upper Lake Pontchartrain basin, a review of the existing vegetation patterns and their possible causes, and a discussion of restoration targets and priorities. The Mississippi River produced the St. Bernard Delta 3000–4000 years ago, trapping fresh water to produce both Lake Maurepas and Lake Pontchartrain (Frazier 1967). The natural vegetation of much of the region remains fresh or brackish marshes, mixed with swamps dominated by bald cypress ( Taxodium distichum ) and tupelo ( Nyssa aquatica ). Yearly flooding by the Mississippi River was once a major factor controlling vegetation patterns, but these processes have been greatly impaired by the construction of artificial levees for flood control. Humans also removed most of the cypress swamps in a pulse of logging between 1876 and 1956. Continued subsidence of the land, slowly rising sea levels, salinity pulses from hurricanes, and canals from the Gulf of Mexico, add further stress to these wetlands. Over the past century there has been a steady loss of wetland area, and a gradual conversion of fresh water to salt water vegetation types. Biotic processes are also important. An exotic species of mammal, nutria ( Myocastor coypus ), consumes both aboveground and belowground parts of wetland plants. Reforestation is strictly limited by the combination of salt pulses, competition, and nutria. Alligators are the top predator in this system, but their potential for reducing the impacts of nutria has received minimal attention from biologists. There are many potential future states for this ecosystem. In the extreme case of rising sea level and warmer climate, the area may become a salt and brackish embayment fringed with mangroves. The state closest to historical conditions would be large areas of bald cypress swamp. Two important priorities are to increase flow of freshwater into the system from multiple pulsed fresh water diversions, and to decrease saltwater intrusions by closing canals such as the Mississippi River Gulf Outlet.
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Merten, Amy A., C. B. Henry e Jacqueline Michel. "DECISION-MAKING PROCESS TO USE IN-SITUBURNING TO RESTORE AN OILED INTERMEDIATE MARSH FOLLOWING HURRICANES KATRINA AND RITA". International Oil Spill Conference Proceedings 2008, n.º 1 (1 de maio de 2008): 545–50. http://dx.doi.org/10.7901/2169-3358-2008-1-545.
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ABSTRACT In-situ burning was used to remove approximately 100–200 barrels (bbls) of Louisiana Sweet Crude (API 33.8) from an intermediate marsh of the Mississippi River delta oiled during the 2005 hurricanes. The marsh was heavily and moderately oiled (approximately 1.6–2.46 hectares and 5–6.5 hectares, respectively). Chevron conducted two burns on October 12 and 13, 2005, 6 weeks after the initial spill. A cooperative monitoring effort was established to quantitatively evaluate recovery in three areas:Oiled and burned;Oiled and unburned; andUnoiled and unburned. Chemical analyses demonstrated that marsh surface soil concentrations of total petroleum hydrocarbons (TPH) and total polycyclic aromatic hydrocarbons declined at similar rates after eight and five months, respectively. A variety of operational and environmental requirements were needed for a successful burn. This paper will:Discuss the advantages and disadvantages of the site for conducting a burn;Discuss the rapid decision-making process to approve the burn during significant post-hurricane response activities;Describe pre-, during- and post-burn operations and observations;Report lessons learned; andHighlight recovery endpoints measured during the monitoring study. This site represents a successful case study for using in-situ burn safely, effectively, and strategically.
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Jaisi, Deb P., Shanshan JI, Hailiang Dong, Ruth E. Blake, Dennis D. Eberl e Jinwook Kim. "Role of Microbial Fe(III) Reduction and Solution Chemistry in Aggregation and Settling of Suspended Particles in The Mississippi River Delta Plain, Louisiana, USA". Clays and Clay Minerals 56, n.º 4 (1 de agosto de 2008): 416–28. http://dx.doi.org/10.1346/ccmn.2008.0560403.
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Zengel, Scott, Jennifer Weaver, Zachary Nixon, Susan L. Wilder, Jeff Dauzat, Chris Sanfilippo, Scott Miles et al. "In Situ Burning and Ecological Recovery in an Oil-Impacted Phragmites australis Tidal Freshwater Marsh at Delta National Wildlife Refuge, Louisiana". International Oil Spill Conference Proceedings 2017, n.º 1 (1 de maio de 2017): 2348–68. http://dx.doi.org/10.7901/2169-3358-2017.1.2348.
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ABSTRACT In situ burning of oiled marshes is a response method that can be more effective and less damaging to the marsh environment than more intrusive manual and mechanical methods, given appropriate conditions for burning. In situ burning has been examined for a variety of oiled marsh types and vegetation species; however, little to no published data are available for in situ burning of oiled Phragmites australis marshes (common reed, Roseau cane). In late May 2014, a pipeline spill occurred in Delta National Wildlife Refuge, Louisiana, releasing an estimated 4,200 gallons of South Louisiana crude oil into a semi-permanently flooded Phragmites tidal freshwater marsh located on the Mississippi River Delta. Due to the remote location, degree of oiling, and difficulty of oil removal within the dense vegetation, an in situ burn was conducted in early June 2014 while the marsh was flooded. In order to examine the effectiveness and environmental effects of in situ burning for this marsh type, and ecological recovery over time, we monitored oiling conditions and ecological metrics for more than two years, comparing sites from three oiling/treatment classes: (a) reference (not oiled or burned), (b) oiled-and-not-burned, and (c) oiled-and-burned. The burn was effective in rapidly removing much of the gross oiling from the marsh, and also reduced residual oiling on the marsh vegetation. Oil concentrations in marsh soils were initially elevated in the oiled-and-burned sites, but were similar to reference conditions and below background levels after three months. Initial oiling and burning drastically affected the marsh vegetation and a common marsh invertebrate; however, overall ecological recovery was relatively rapid and habitat quality in terms of native plant species composition and wildlife value was enhanced by burning at a local scale, at least for several years. Based on these findings, in situ burning appears to be a viable response option to consider during future spills in marshes with similar plant species composition, environmental setting, and oiling conditions.
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Martinec, Ceil C., Jonathan M. Miller, Nathan K. Barron, Rui Tao, Kewei Yu, Paul M. Stewart, Alfred C. Nichols, David A. Steffy e Stephen C. Landers. "Sediment Chemistry and Meiofauna from the Northern Gulf of Mexico Continental Shelf". International Journal of Oceanography 2014 (1 de outubro de 2014): 1–10. http://dx.doi.org/10.1155/2014/625718.
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This study examined sediment chemistry, granulometry, and meiofauna on the northern Gulf of Mexico continental shelf from central Louisiana to Apalachicola, Florida. Sediment samples were collected in October/November 2012 with a Shipek grab sampler from 26 locations (extending from 28°18′46.079′′N, 91°10′44.471′′W to 29°3′48.383′′N, 85°28′25.679′′W) at depths ranging from 49 to 361 m. Sediment analysis revealed two distinct profiles to the east and west of the Mississippi River Delta at approximately 88°30′W. The concentrations of silt + clay, organic carbon, Ba, Cr, Cu, Fe, Ni, Pb, V, and Zn were higher in western sites and positively correlated with Al concentrations. Eastern sites contained sandier sediments with lower organic carbon concentrations and higher Sr and Ca concentrations. Nematode densities were higher at western sites and positively correlated with Al, Cr, Cu, Fe, Ni, Pb, Zn, silt + clay, and organic carbon concentrations. Copepod densities correlated with very coarse + coarse sand, exhibiting higher densities at eastern sites. PAH concentrations were relatively low, with all sites having <1700 µg/kg total PAHs. This study has revealed two distinct sediment profiles in the eastern and western zones of the study, which appear to influence the nematode and copepod densities.
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PYRON, R. ALEXANDER, KYLE A. O’CONNELL, JENNIFER Y. LAMB e DAVID A. BEAMER. "A new, narrowly endemic species of swamp-dwelling dusky salamander (Plethodontidae: Desmognathus) from the Gulf Coastal Plain of Mississippi and Alabama". Zootaxa 5133, n.º 1 (3 de maio de 2022): 53–82. http://dx.doi.org/10.11646/zootaxa.5133.1.3.
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We describe a new, narrowly endemic species of swamp-dwelling dusky salamander (Plethodontidae: Desmognathus pascagoula sp. nov.) from the Gulf Coastal Plain of southeastern Mississippi and southwestern Alabama based on linear morphometrics, mitochondrial DNA, and single nucleotide polymorphisms from 881 loci produced using genotype-by-sequencing. Some populations of the new species were historically referred to as D. auriculatus, a polyphyletic assemblage of at least three species in the Atlantic and Gulf Coastal Plain from Texas to North Carolina. Populations of D. auriculatus from the Gulf Coastal Plain in Louisiana and Mississippi were recently described as D. valentinei. The new species includes populations that were tentatively referred to D. valentinei, but we find it is morphologically, genetically, and geographically distinct. It is smaller, has a more defined dorsal color pattern, more irregular whitish “portholes” in up to three rows on the lateral surfaces of the body and tail, and a brighter orange or yellowish orange postocular stripe. At present, the new species is known from only six extant populations in the lower Pascagoula, Escatawpa, and Mobile drainages. The latter represents a distinct phylogeographic lineage. We also refer a historical collection from the northeastern side of the Mobile-Tensaw River Delta to this species, suggesting a much broader range in the past. We suspect that more populations remain to be discovered in the area, and their potential species-level distinctiveness should be tested further. This discovery increases knowledge of the biodiversity in the southeastern United States Coastal Plain, a candidate region meeting the global criteria for a “biodiversity hotspot,” and underscores the amount of cryptic diversity likely remaining to be discovered and described in Nearctic salamanders.
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Du, Jiabi, Kyeong Park, Jian Shen, Yinglong J. Zhang, Xin Yu, Fei Ye, Zhengui Wang e Nancy N. Rabalais. "A hydrodynamic model for Galveston Bay and the shelf in the northern Gulf of Mexico". Ocean Science 15, n.º 4 (17 de julho de 2019): 951–66. http://dx.doi.org/10.5194/os-15-951-2019.
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Abstract. A 3-D unstructured-grid hydrodynamic model for the northern Gulf of Mexico was developed, with a hybrid s–z vertical grid and high-resolution horizontal grid for the main estuarine systems along the Texas–Louisiana coast. This model, based on the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), is driven by the observed river discharge, reanalysis atmospheric forcing, and open boundary conditions from global HYCOM output. The model reproduces the temporal and spatial variation of observed water level, salinity, temperature, and current velocity in Galveston Bay and on the shelf. The validated model was applied to examine the remote influence of neighboring large rivers, specifically the Mississippi–Atchafalaya River (MAR) system, on salinity, stratification, vertical mixing, and longshore transport along the Texas coast. Numerical experiments reveal that the MAR discharge could significantly decrease the salinity and change the stratification and vertical mixing on the inner Texas shelf. It would take about 25 and 50 d for the MAR discharge to reach the mouth of Galveston Bay and Port Aransas, respectively. The influence of the MAR discharge is sensitive to the wind field. Winter wind constrains the MAR freshwater to form a narrow lower-salinity band against the shore from the Mississippi Delta all the way to the southwestern Texas coast, while summer wind reduces the downcoast longshore transport significantly, weakening the influence of the MAR discharge on surface salinity along Texas coast. However, summer wind causes a much stronger stratification on the Texas shelf, leading to a weaker vertical mixing. The decrease in salinity of up to 10 psu at the mouth of Galveston Bay due to the MAR discharge results in a decrease in horizontal density gradient, a decrease in the salt flux, and a weakened estuarine circulation and estuarine–ocean exchange. We highlight the flexibility of the model and its capability to simulate not only estuarine dynamics and shelf-wide transport, but also the interactions between them.