Physical Sciences and Mathematics Commons^™

Effects Of Marsh Management In Coastal Marsh Impoundments On Marsh Vertical Accretion In The Face Of Sea Level Rise., Scott P. Graham

LSU Master's Theses

Many coastal marshes are managed for wildlife through the use of levees and water control structures. Management techniques such as water manipulation, herbicide application, and controlled burns are used to set back succession and facilitate recruitment of annual plant species, which are highly sought after by many wildlife. These marsh impoundments alter or prevent natural tidal exchange, which might alter or prevent sediment and nutrient inputs to the marsh. Although these management techniques are effective in managing for wildlife, there are few studies comparing vertical accretion between managed and unmanaged marshes. Vertical accretion is important because it allows coastal wetlands …

The Tensile Root Strength Of Spartina Patens Declines With Exposure To Multiple Stressors, R. Eugene Turner, Lauris O. Hollis

Faculty Publications

Coastal wetlands may be subjected to numerous biotic and abiotic stressors from natural and anthropogenic forces in the landscape. The influx of nutrients, inorganic compounds and xenobiotics are suspected of degrading the belowground biomass of coastal macrophytes. Spartina patens acts as an ecosystem engineer for lower salinity coastal marshes and its biomechanical properties are vital to the stability and resilience of coastal wetlands. S.patens was exposed to one natural (flooding) and two anthropogenic stressors (atrazine and nutrient addition) in a greenhouse experiment to test the hypothesis that these three stressors reduce the tensile root strength of S. patens. A one-way …

Phosphorus Variability In The Area Of Influence Of The Mid-Barataria Sediment Diversion, Peter Mates

LSU Master's Theses

Man-made levees along the lower Mississippi River prevent delivery of sediment from building and maintaining Louisiana’s coastal wetlands. The Mid-Barataria sediment diversions is designed to reintroduce Mississippi River water, sediment, and nutrients into the sediment-starved Barataria Basin. Phosphorus (P) is an important macronutrient for regulating primary production in coastal marine ecosystems. Wetlands can serve as a sink or source for phosphorus to the overlying water column through various retention and release processes, dependent on concentration. Louisiana coastal systems can be phosphorus limited due to much higher concentrations of bioavailable Nitrogen in river water. The high soluble molar N:P ( >50:1) …

Deltaic Wetland Dynamics From Seasonal To Centennial Scales, Giancarlo A. Restreppo

LSU Doctoral Dissertations

The lower plain of the Mississippi River Delta contains approximately five coastal sedimentary basins that are topographically defined, and one shelf-crossing depocenter (the Birds Foot Delta). These depositional systems receive varying quantities of sediment from fluvial and marine sources and have rates of coastal land loss that are roughly inversely proportional to fluvial sediment supply. To combat land loss along these regions, Louisiana has launched a historic campaign to sustain and regrow coastal lands using, in part, river sediment diversions. Fine sediments constitute the majority of sediment load in the Mississippi River, but are under-studied with respect to dispersal processes, …

From The River To The Gulf: An Investigation Of Biogeochemical Cycling In Wetland Soils And Coastal Shelf Sediments, Katie Bowes

LSU Master's Theses

Louisiana is home to 40% of the coastal wetlands in the lower 48 states, yet accounts for 80% of the coastal wetland loss in this region. This loss is attributed to decreased sediment supply, levee alteration, sea level rise, channelization, and subsidence. The levee system in Louisiana disconnected coastal wetlands from the main stem of the Mississippi River (MSR), reducing the amount of land-building sediment that reaches coastal wetlands. This disconnection also allows a greater percentage of river discharge, including agricultural contaminants and runoff, to flow into the northern Gulf of Mexico (NGOM).

The 2012 Coastal Master Plan proposed eight …

The Tensile Root Strength Of Emergent Coastal Macrophytes, Lauris Olivia Hollis

LSU Doctoral Dissertations

Spartina patens is a dominant emergent macrophyte in fresh, intermediate, and brackish marshes along the Atlantic and Gulf coasts of United States where its biomechanical properties are a key component of wetland health and resilience. Its root biomass and tensile root strength are essential for anchorage, erosion protection, and are important determinants of soil strength. Nutrients and the herbicide atrazine are suspected of negatively impacting this wetland plant and others. The objectives of this study were to: 1) ascertain the tensile root strength of five emergent coastal macrophytes in coastal estuaries, and 2) test the effects of nutrient addition, atrazine …

Living On The Edge: An Assessment Of The Habitat Use Of Waterbirds In Estuarine Wetlands Of Barataria Basin, La, Brett Ashley Patton

LSU Master's Theses

The wetlands of Louisiana are losing area at the rapid rate of 42.9 km2 yr-1 and the trend is expected to continue. This combined with expected sea-level rise will likely cause large shifts in vegetation and salinity regimes that will affect the wildlife species reliant on these ecosystems. Waterbirds serve as indicator species of ecosystem health in estuarine wetland habitats; therefore, these species are often the targets of wetland management goals in Louisiana. However, many proposed wetland restoration projects are focused primarily on social impacts with only a few specific waterbird species designated for management. The majority of these waterbird …

Ecological-Hydrological Feedback In Forested Wetlands, Scott Thomas Allen

LSU Doctoral Dissertations

In forested wetlands, the biotic and abiotic consequences of water level variability is not well understood. The effects of flooding on carbon and water exchanges are important knowledge gaps where progress could benefit management of natural resources and predicting of changes in surface geophysical cycles. Two specific needs are a better understanding of (1) wetland tree responses to hydrologic variations, and (2) the effects of the forest and associated tree stressors on surface energy and water fluxes. Objectives were to determine effects of flooding on evaporation rates and energy dynamics, tree water use and growth responses to river-floodplain connectivity and …

Influences On The Successful Implementation Of The Convention On Wetlands Of International Importance (Ramsar) Among Member Countries, Aziza Saud Al Adhoobi

LSU Master's Theses

Wetlands are very dynamic ecosystems and are featured all over the world’s landscape. Recent studies suggested that wetlands are in continuous decline, both and quantity and quality and between 64-71% is the estimated global wetland loss in the 20th century (Davidson 2014; Gardner et al., 2015). Therefore, as wetland loss increases around the world, more effort to protect and restore wetland habitat, values, and services become crucial. For this reason, the Ramsar Convention was established four decades ago to highlight the severity of wetland loss and to produce guidelines that aim to guide Contracting Parties toward sustainable and efficient management …

Vegetation Influences Microbial Community Structure And Methane Emissions In Southeastern Louisiana Wetlands, Anthony Jason Rietl

LSU Doctoral Dissertations

Methane has a warming potential 28 times that of carbon dioxide and has been increasing in the Earth’s atmosphere since 1750. An understanding of the dynamics of methane emissions from natural sources is becoming increasingly important as we may need to mitigate emissions from these sources in the future to help reduce the effects of climate change. Wetlands are the single largest natural source of methane; however, little attention has been given to how plant species, biota, and interactions between above and belowground communities and microbial communities may affect methane emissions. First, microbial community structure and function was assessed for …

Analyzing Site Suitability For Baldcypress (Taxodium Distichum) Regeneration Along A Hydrologic Gradient In South Louisiana Swamps, Marcus Rutherford

LSU Master's Theses

The future of Louisiana’s coastal cypress-tupelo forests is threatened by prolonged or permanent flooding during the growing season. Permanent inundation prevents baldcypress seedlings from becoming established. The upper limit of submergence with respect to adequate planted baldcypress seedling performance has not been effectively tested under actual field conditions. Similarly, an effective method for determining a site’s regeneration potential based on present vegetation attributes has not been developed. To test first-year performance of planted baldcypress seedlings under varying levels of submergence, I planted 900 of both 1-0 and 2-0 age-class bare-root seedlings across 12 different sites covering a range of hydrologic …

Holecene Paleoenvironmental Reconstruction From The Shark River Estuary, Everglades, Florida, Qiang Yao

LSU Doctoral Dissertations

This dissertation examines the paleoecological records from the Shark River Estuary in the southwestern part of the Everglades National Park (ENP), Florida, with primary goal of reconstructing the Holocene history of the coastal mangrove ecosystem in the Florida Coastal Everglades. Roughly 15 meters of sediments were collected from 4 study sites and subjected to loss-on ignition, palynological, and X-ray fluorescence analyses. According to the literature, the earliest communities of Rhizophora mangle (red mangrove) occurred prior to 8,000 cal yr BP in the south-central area of the Belize Barrier Reef Platform. Between 7,000 and 5,000 cal yr BP, Rhizophora was established …

Anthropogenic Impacts On Soil Microbial Processes In Coastal Wetlands: Nutrient Loading And Rising Co2 Levels, Havalend Ellen Steinmuller

LSU Master's Theses

Atmospheric carbon dioxide (CO2) levels and global eutrophication are anthropogenic stressors impacting the environment of specific interest in wetland systems. Wetlands occupy a critical interface between terrestrial and aquatic environments. Fertilizer use for agriculture and treated wastewater disposal has increased nutrient loading to wetlands. Conflicting results on impacts of nitrogen loading to coastal wetland soils have been reported, though most studies have investigated short-term impacts of nutrient loading, not long-term integrated impacts. I investigated an 11-year period of nutrient loading on soils in an oligohaline coastal wetland. Nitrogen treatments of 0, 50, 200, and 1200 kg ha-1 yr-1 were paired …

The Adoption Of State Wetland Policies: How Do Wetlands Fit Within The Theoretical Framework Of Environmental Policy Determinants?, Rachel Bogart Krech

LSU Master's Theses

Wetlands are an extremely important natural resource in the United States. They offer storm surge protection, sediment stabilization, groundwater recharging, carbon sequestration, and habitat for many species. Despite their values, wetlands have a long history of being misunderstood. It was not until the mid-1970s that scientific understanding helped transform policy from that of rapid conversion to that of conservation. By this time, the lower 48 states had already lost 53 percent of its total wetlands. The nature of wetlands and federal limitations make the management of this natural resource a primarily state-based responsibility. However, the way that states construct their …

Some Effects Of Nutrient And Flooding Stress Manipulation On Coastal Louisiana Wetland Vegetation, James Stephen Ialeggio

LSU Master's Theses

Freshwater diversions are a relatively recently utilized tool in wetland loss mitigation that stimulate an organic accretion response in marsh vegetation, which is based in root production and thus belowground biomass. The effectiveness of freshwater diversions in slowing marsh loss probably varies across a gradient of the factors they supply: decreased salinity, increased nutrient concentrations, and increased inundation. Flooding stress is commonly thought to be the overriding factor limiting wetland vegetation growth, however its influence may vary across salinity and nutrients. Therefore, plugs of Spartina patens were planted in four “marsh organs” consisting each of 36 sediment-filled PVC pipes of …

Spatial Structure And Dynamics Of The Plant Communities In A Pro-Grading River Delta : Wax Lake Delta, Atchafalaya Bay, Louisiana, Melissa Carle

LSU Doctoral Dissertations

River deltas are dynamic depositional environments that are controlled to varying degrees by coastal and fluvial forces. Plant communities in deltas respond to many of the same allogenic forces that shape delta geomorphology. This study examines the factors that influence plant community development, productivity, and species distributions in the Wax Lake delta, a young, actively pro-grading river delta in coastal Louisiana, USA. A species distribution map created using high-resolution 8-band WorldView-2 imagery was found to have an overall accuracy of 75 percent. Classification tree analysis suggested that most of the observed variation in plant species distributions within the delta can …

The Effect Of Habitat Change On Nutrient Removal In The Atchafalaya River Basin, Louisiana, Amy E. Scaroni

LSU Doctoral Dissertations

The Mississippi and Atchafalaya rivers are the major sources of freshwater and nutrients to the Gulf of Mexico. Increased nutrient loads from these rivers exacerbate eutrophication in coastal receiving waters and contribute to the large area of hypoxia that develops seasonally in the Gulf. Levees along the Mississippi River have reduced contact between the river and the historic floodplain; this limits the ability of floodplain wetlands to naturally mitigate excess nutrients. However, the Atchafalaya River diverges from the Mississippi 217 km from the Gulf and enters a large river floodplain with a widely spaced levee system. This enhances the ability …

Edaphic And Vegetative Controls On Mercury Cycling In Oligohaline Wetlands, Jonathan M. Willis

LSU Doctoral Dissertations

With the expansion of the human population and associated industries there is a concomitant increase in both resource utilization and the production of waste and deleterious by-products. Mercury is a naturally-occurring toxic metal with a complicated and unique biogeochemical cycle, and is often a contaminant of ecotoxicological concern in unindustrialized aquatic habitats. The research described herein was designed to elucidate multiple aspects regarding the behavior of mercury in oligohaline wetland habitats, particularly with respect to edaphic and vegetative effects, through a monitoring and characterization study as well as a series of manipulative experiments. The observational study, conducted in the wetlands …

Dendrochronological Analysis Of Productivity And Hydrology In Two Louisiana Swamps, John Blake Amos

LSU Master's Theses

Modified river flows and land subsidence have subjected many coastal swamp forests in the delta of the Mississippi River to greatly altered flooding, sediment, and nutrient regimes. These areas have become inundated to greater depth, duration, and frequency and either are connected to the river and receive drastically increased sediment and nutrients (riverine swamps) or have become disconnected from riverine flooding (stagnant swamps) and receive little or no sediment and nutrient input. To better understand how these changes are affecting ecosystems, dendrochronological techniques for baldcypress (Taxodium distichum L. Rich.) were used at three sites in each of two contrasting swamps …

Designation Of The Southwest National Wildlife Refuge Complex As Wetlands Of International Importance Under Ramsar, Convention On Wetlands Of International Importance, Mitchell Ward Coffman

LSU Master's Theses

The historical loss and continued threat of loss of Louisiana wetlands is a major environmental concern for the United States and the world. In 1971, the Ramsar Convention, an international environmental treaty was ratified to specifically address conservation planning and land use management issues involving wetlands of the world. Ramsar provides an international designation award called, the Wetlands of International Importance List, which formally acknowledges globally important wetland landscapes. Ramsar outlines specific criterion nominated wetland sites must possess for consideration of this listing.

The Southwest Louisiana National Wildlife Refuge Complex is an excellent candidate for nomination to the Ramsar Convention …

Scientific And Management Perspectives In Wetland Groundwater Hydrology, Lorna Veronica Inniss

LSU Doctoral Dissertations

Wetland groundwater hydrology was investigated at different spatial scales to assess the usefulness of the information to coastal managers. Specific objectives were to: (1) review studies related to coastal groundwater discharge, evaluating techniques and identifying controls; (2) understand regional trends in groundwater flow along the U.S. East and Gulf coasts; (3) evaluate the applicability of naturally occurring radioisotopes as indicators of groundwater in a shallow deltaic system; and (4) evaluate groundwater-surface water exchange within Barataria Basin, Louisiana. Results of the review confirmed discharge estimates vary over several orders of magnitude, due to differences in precipitation and tidal prisms. In addition, …