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- Eutrophication (2)
- Louisiana (2)
- Nitrogen (2)
- Agriculture (1)
- Artificial reef (1)
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- Atlantic croaker (1)
- Backfilling (1)
- Bay anchovy (1)
- Belowground production (1)
- Can Gio mangrove forest (1)
- Canals (1)
- Cost (1)
- DEA (1)
- Davis Pond freshwater diversion (1)
- Decomposition (1)
- Disturbance (1)
- Dredging (1)
- Elevation (1)
- Estuary (1)
- Feeding ecology (1)
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- Groundwater-surface water interactions (1)
- Gulf of Mexico (1)
- Gut-content analysis (1)
- Hydrology (1)
- Hypoxia (1)
- Individual-based model (1)
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Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
Restoration Of Dredged Canals In Wetlands: A Comparison Of Methods, Joseph Baustian, R. Eugene Turner, Nancy F. Walters, David P. Muth
Restoration Of Dredged Canals In Wetlands: A Comparison Of Methods, Joseph Baustian, R. Eugene Turner, Nancy F. Walters, David P. Muth
Faculty Publications
A comparison of two methods for restoring dredged canals to wetlands was examined at the Jean Lafitte National Historical Park and Preserve’s Barataria Preserve Unit near New Orleans, LA. Both northern and southern canals had the remnant dredged spoil material returned to the canal, but the southern canal had additional sediment pumped in from a nearby lake. The water depth in the southern canal shallowed significantly from 1.2 to 0.4 m following backfilling and sediment addition, while the depth of the northern canal (which received no additional sediment) remained unchanged following backfilling. Neither site had complete soil restoration, but the …
Below- And Aboveground Biomass Of Spartina Alterniflora: Response To Nutrient Addition In A Louisiana Salt Marsh, Faith A. Darby, R. Eugene Turner
Below- And Aboveground Biomass Of Spartina Alterniflora: Response To Nutrient Addition In A Louisiana Salt Marsh, Faith A. Darby, R. Eugene Turner
Faculty Publications
The responses of Spartina alterniflora above- and belowground biomass to various combinations of N, P, and Fe were documented in a 1-year field experiment in a Louisiana salt marsh. Five levels of N additions to 0.25 m2 plots resulted in 18% to 138% more live aboveground biomass compared to the control plots and higher stem densities, but had no effect on the amount of live belowground biomass (roots and rhizomes; R&R). There was no change in the aboveground biomass when P or Fe was added as part of a factorial experiment of +P, +N, and +Fe additions, but there was …
Elucidating Marine Pore Water Exchange And Fresh Aquifer Sources In Estimates Of Submarine Groundwater Discharge To A Coastal Lagoon, Christopher Gerald Smith
Elucidating Marine Pore Water Exchange And Fresh Aquifer Sources In Estimates Of Submarine Groundwater Discharge To A Coastal Lagoon, Christopher Gerald Smith
LSU Doctoral Dissertations
Dynamic balances between fresh groundwater, saline groundwater, and surface water control the physics and chemistry of subterranean estuaries. Investigations were performed in a subterranean estuary on physical processes contributing to fresh groundwater and saline water mixing, vertical and lateral positioning of this mixing zone, and how this mixing affects spatial and temporal distributions of 234,238U, 226Ra, and 222Rn. The subterranean estuary is located in an unconfined aquifer beneath Indian River Lagoon, Florida, USA, where I could examine redox responses to altered flow regimes. Continuous groundwater and surface water level measurements suggest a strong hydrologic connection between this …
Effect Of Hydrology On The Structure And Function Of Mangrove Ecosystems In The Can Gio Mangrove Biosphere Reserve, Vietnam, Loi Tan Le
LSU Doctoral Dissertations
The influence of hydrology on the mangrove forests of Vietnam has received little scientific attention, even though hydrology is recognized as the primary forcing function in mangrove ecosystems worldwide. The purpose of this dissertation research was to determine the effects of hydrology on specific structural attributes and functional processes within the mangrove forests of Can Gio, a province in southeastern Vietnam. Khe Vinh (KV) and Mui O (MO), two locations within compartment 17 of the Can Gio Mangrove Biosphere Reserve, were chosen as study sites. This research addressed two questions: (1) What are the characteristics of the hydrological regime at …
A Century Of Land Use And Water Quality In Watersheds Of The Continental U.S., Whitney P. Broussard Iii
A Century Of Land Use And Water Quality In Watersheds Of The Continental U.S., Whitney P. Broussard Iii
LSU Doctoral Dissertations
Human endeavors, particularly the agricultural and industrial activities of the last half century, now produce more biologically available nitrogen (N) than all other natural sources combined. The increased N availability can have consequences for the health of aquatic biota on the local, regional, and global scales. One manifestation of this problem is the formation of coastal hypoxic zones where terrestrial N loading creates eutrophic conditions in coastal waters. This dissertation examines a century of changes in land use and water quality to quantify the relationships between agricultural land use practices and riverine N yields in the Mississippi River Basin and …
Swamp Ecology In A Dynamic Coastal Landscape: An Investigation Through Field Study And Simulation Modeling, Susanne Sigrid Hoeppner
Swamp Ecology In A Dynamic Coastal Landscape: An Investigation Through Field Study And Simulation Modeling, Susanne Sigrid Hoeppner
LSU Doctoral Dissertations
Increased flooding, nutrient and sediment deprivation, and saltwater intrusion have been implicated as probable causes of coastal swamp deterioration in the Mississippi Delta. An understanding of the interactive effects of these factors is required to enable successful planning of wetland restoration activities. I used field data collected from 2000 till 2005 at forty study sites to characterize the baseline conditions of the Maurepas swamp. I used a cluster analysis to identify four swamp habitat clusters, and characterized the clusters on the basis of soil properties, salinity, basal area, stem density, and other tree-related variables. ANOVA and related statistical techniques showed …
Assessment Of Oxygen Sources And Sinks In The Northern Gulf Of Mexico Using Stable Oxygen Isotopes, Zoraida Jazmin Quinones-Rivera
Assessment Of Oxygen Sources And Sinks In The Northern Gulf Of Mexico Using Stable Oxygen Isotopes, Zoraida Jazmin Quinones-Rivera
LSU Doctoral Dissertations
Coastal hypoxia (< 2 mg O2L-1) represents a global problem that continues to worsen as nutrient fluxes to these areas increase. The second largest zone of human-induced hypoxia is located on the Louisiana continental shelf where hypoxic bottom waters commonly occur during summertime. This region is strongly impacted by the large flux of freshwater and nutrients from the Mississippi River, which influences both biological and physical processes that control oxygen dynamics. Yet, based on oxygen concentration measurements alone, it is difficult to separate the effects of biological factors from physical factors. To address this problem, I used a dual budget approach to assess the importance of oxygen sources and sinks on the Louisiana continental shelf. The dual budget was based on using stable oxygen isotopes (ä18O) in combination with conventional oxygen concentration measurements. To analyze temporal trends, surface and bottom water samples were collected monthly between July 2001 and July 2003 along an onshore-offshore transect. For better spatial resolution, shelfwide sampling was conducted extending from the Mississippi River Delta to the Louisiana-Texas border in the month of July of 2001, 2002, and 2003. Oxygen saturations values ranged between 180% at the surface and almost 0% close to the bottom with a corresponding range of ä18O values from 15‰ to 50‰. Biological parameters were important during all seasons for surface oxygen dynamics. The effects of physical factors were less apparent, except during severe physical disturbances. Bottom water oxygen dynamics showed clear seasonal signals of high oxygen depletion and larger contributions of benthic respiration during the summer, which corresponded to the strong stratification of the water column. In bottom waters, summer oxygen depletion was predominantly due to benthic respiration, accounting for about 73%, 80% and 60% of the total oxygen loss for 2001, 2002 and 2003 respectively. Model estimates of production/respiration (P/R) ratio during the July shelfwide cruises indicated that surface waters were productive with an average calculated P/R above 1. Depth stratified sampling (5 m intervals), which started in July 2002, showed that productivity in the mixed layer (5 to 10 m) was not homogeneous. Calculated P/R exceeded 1 only in the surface layer, while at 5 m P/R was approximately 1 and at a depth of 10 m, P/R was less than 1. Additionally, hypoxic conditions were only detected within 5 m of the bottom sediments. The dual budget approach yielded new estimates of productivity dynamics in surface waters and of sediment oxygen demand in bottom waters. For the first time, this study provided routine insight into productivity and respiration dynamics over large temporal and spatial scales. This could not have been accomplished using traditional methods because they commonly rely on time-consuming incubations. The study has shown that respiration dynamics in bottom waters vary seasonally with higher contribution of benthic respiration during stratified summer conditions and prevalent water column respiration during fall and winter. In contrast, seasonality in surface waters was less pronounced as productivity was more dependent on (salinity-inferred) nutrient supply than climatic forcing.
Landscape Analysis Of Vegetation Change In Coastal Louisiana Following Hurricanes Katrina And Rita, Gregory Dean Steyer
Landscape Analysis Of Vegetation Change In Coastal Louisiana Following Hurricanes Katrina And Rita, Gregory Dean Steyer
LSU Doctoral Dissertations
Investigations of hurricane disturbances on coastal vegetated communities are common, but relatively few are comprehensive across broad geographic regions. The 2005 hurricanes, Katrina and Rita, exposed Louisiana coastal landscapes to physical modifications and extensive and prolonged flooding, resulting in measurable physicochemical changes. This research used remote sensing and field investigations to regionally assess (1) porewater salinity and sulfide impacts to and recovery of coastal Louisiana vegetation communities, and (2) the importance of mineral sediment deposition on accretionary processes. Hurricane effects were most direct and prominent in eastern Louisiana from Katrina and western Louisiana from Rita, compared to central Louisiana exposed …
Denitrification Enzyme Activity As An Indicator Of Nitrate Loading In A Wetland Receiving Diverted Mississippi River Water, Lisa Michelle Gardner
Denitrification Enzyme Activity As An Indicator Of Nitrate Loading In A Wetland Receiving Diverted Mississippi River Water, Lisa Michelle Gardner
LSU Master's Theses
The Davis Pond freshwater diversion discharges nutrient-rich Mississippi River water to a 3,760 ha receiving marsh in upper Barataria Basin, LA. Excess nitrate in the Mississippi River has been linked to algal blooms and hypoxia in the Gulf of Mexico with potential to negatively impact Barataria Basin. We hypothesized that 1) soil denitrification enzyme activity (DEA) will increase with higher surface water nitrate concentrations, and 2) the spatial distribution of DEA in Davis Pond marsh will provide information about the extent nitrate loading at a specific discharge rate. Intact soil cores collected from the marsh received a continuous flow of …
The Effect Of An Inshore Artificial Reef On The Community Structure And Feeding Ecology Of Estuarine Fishes In Barataria Bay, Louisiana, Kirsten A. Simonsen
The Effect Of An Inshore Artificial Reef On The Community Structure And Feeding Ecology Of Estuarine Fishes In Barataria Bay, Louisiana, Kirsten A. Simonsen
LSU Master's Theses
Recently we have begun to understand the importance of inshore hard-bottom substrate, including oyster reefs, to estuarine fish communities in the Gulf of Mexico, especially in the context of identifying Essential Fish Habitat (EFH). However, problems such as habitat loss, disease, overharvest, and failure to replace shell have severely decreased the amount of high-relief oyster reef habitat available to finfish. The purpose of this project was to establish an artificial high-relief mimic-oyster reef in Barataria Bay, Louisiana, and monitor its use by economically and ecologically important finfish, including spotted seatrout (Cynoscion nebulosus) and Atlantic croaker (Micropogonias undulatus). The finfish and …