Physical Sciences and Mathematics Commons^™

Doubt And The Values Of An Ignorance-Based World View For Restoration: Coastal Louisiana Wetlands, R. Eugene Turner

Faculty Publications

Embracing doubt, a signature strength of science, is an essential core component of an ignorance-based-world view (IBWV) that assumes the areas of certainty are small relative to the large field of ignorance. The contrasting knowledge-based world view (KBWV) assumes that small and mostly insignificant knowledge gaps exist. When the KBWV is combined with a sense of urgency to “do something,” then the intellectual landscape is flattened, the introduction of new ideas is impeded, monitoring and adaptive management is marginalized, risky behaviors continue, and social learning is restricted. The history of three coastal Louisiana land-uses (agricultural impoundment, marsh management, and dredging) …

Nutrient Limitation On Phytoplankton Growth In The Upper Barataria Basin, Louisiana: Microcosm Bioassays, Ling Ren, Nancy N. Rabalais, R. Eugene Turner, Wendy Morrison, Warren Mendenhall

Faculty Publications

The Davis Pond Diversion (DPD) was constructed to divert Mississippi River (MR) water into the Barataria Basin to reduce the salinity in support of wetland restoration on the Louisiana coast. To assess the phytoplankton nutrient limitation in adjacent water systems and potential impacts of DPD, 12 seasonal nutrient-phytoplankton bioassay experiments were conducted from October 2003 to July 2004 using the natural phytoplankton assemblages from freshwater and brackish-water lakes, Cataouatche and Salvador, LA (USA), which receive Mississippi River water from the DPD, and from a nearby freshwater lake, Lac des Allemands, that does not. Dissolved inorganic nitrogen (N), phosphorus (P), and …

Nutrient Enrichment Drives Gulf Of Mexico Hypoxia, Donald F. Boesch, Walter R. Boyton, Larry B. Crowder, Robert J. Diaz, Robert W. Howarth, Laurence D. Mee, Scott W. Nixon, Nancy N. Rabalais, Rutger Rosenberg, James G. Sanders, Donald Scavia, R. Eugene Turner

Faculty Publications

No abstract provided.

Comments On Buzan Et Al. “Positive Relationships Between Freshwater Inflow And Oyster Abundance In Galveston Bay, Texas”, R. Eugene Turner

Faculty Publications

Buzan et al. critique Turner’s (Estuaries and Coasts 29:345–352, 2006) analysis of the relationship between freshwater inflow and oyster productivity in the Gulf of Mexico, using 16 years of fisheries-independent data for Galveston Bay. They conclude that the catch-per-unit effort (CPUE; number h−1) of marketable oysters increase 1 to 2 years after years with increased freshwater inflows, and they express concerns that water supply managers may mis-apply the results of Turner (Estuaries and Coasts 29:345–352, 2006) to justify a reduced freshwater inflow to Galveston Bay. I find no relationship between the CPUE of oyster spat or marketable oyster density and …

Assessing Linkages Between Petroleum Platforms And Pelagic Fishes Using Telemetry With Emphasis On Blue Runner (Caranx Crysos), Harmon Brown

LSU Doctoral Dissertations

Petroleum platforms number greater than 4,200 in the Gulf of Mexico and Caranx crysos (blue runner) is one of the most abundant fish species around these platforms. Forty-six blue runner were tagged with acoustical transmitters in August 2005, though the study was terminated prematurely due to the impending arrival of Hurricane Katrina. Nineteen blue runner were tagged in September 2006 and tracked for up to two months. Blue runner exhibited limited site fidelity around the platforms in 2005. The home range of twenty-three blue runner was calculated in 2005. A significant difference was found between the fork length of the …

Barrier Island Migration Over A Consolidating Substrate, Julie Dean Rosati

LSU Doctoral Dissertations

Barrier islands that overlie a compressible substrate load and consolidate the underlying subsurface. Through time, the elevation and aerial extent of these islands are reduced, making them more susceptible to inundation and overwash. Sand washed over the island and onto back-barrier marsh or into the bay or estuary begins the consolidation process on a previously non-loaded substrate, with time-dependent consolidation a function of the magnitude of the load, duration of load, and characteristics of the substrate. The result is an increase in the overwash, migration, breaching, and segmentation of these islands. This research determined the degree to which consolidation affects …

Storm Surge Dynamics Over Wide Continental Shelves: Numerical Experiments Using The Finite-Volume Coastal Ocean Model, Joao Lima Rego

LSU Doctoral Dissertations

Storm surge is an abnormal rise of the sea surface caused by atmospheric forcing, including the wind stress and atmospheric pressure associated with extra-tropical and tropical cyclones. Hurricanes and typhoons have a great impact on coastal regions, and can cause severe loss of lives and great damages. A systematic investigation of storm surge impact to the coasts of Louisiana and Texas, where the continental shelf reaches up to 200 km in width, is conducted here using the hydrodynamics Finite-Volume Coastal Ocean Model, FVCOM (Chen et al., 2003). The model is applied to the northern Gulf of Mexico to simulate the …

Bottom Boundary Layer Physics And Sediment Transport Along A Transgressive Sand Body, Ship Shoal, South-Central Louisiana: Implications For Fluvial Sediments And Winter Storms, Daijiro Kobashi

LSU Doctoral Dissertations

Ship Shoal, a shore-parallel sand body, was recently recognized as having a unique physical and biological environment and also as a potential sand resource for coastal restoration in coastal Louisiana. Little is known regarding such dynamics, in concert with fluvial sediments and winter storms, influenced in unique ecosystems, and likely in future potential sand mining. This dissertation addresses such the morphodynamics and sedimentary processes and their implications for the mining from the shoal using field measurements and numerical modeling studies. During the winter-spring season, fluvial sediment plumes shifted from the prevailing west to southeast during the post-frontal phases, resulted in …

Proxy Records Of Paleohurricanes For The Western And Southern Caribbean, Terrence Allen Mccloskey

LSU Doctoral Dissertations

This dissertation evaluates the hypothesis that hurricane activity levels in the North Atlantic during the late Holocene have been driven by latitudinal movements of the North Atlantic circulation system. Multi-millennial sedimentary proxy records, based on the occurrence of overwash clastic layers, provide clear evidence of abruptly alternating periods of hurricane landfall frequency for Nicaragua and Belize. Three Belizean transects exhibit an Active period (hyperactivity) occurring from ~2000-6000 cal yr BP, although dating is inconsistent across the transects. An Active period covering the last 500 years is found at one location. The Nicaraguan record, derived from three transects covering >90 km …

Fine- To Basin-Scale Distributions Of Calanus Finmarchicus And Its Predators In Three Deep Basins Of The Gulf Of Maine During December 1998 And 1999 From Video Plankton Recorder (Vpr) Data, Christian Briseño-Avena

LSU Master's Theses

The calanoid copepod Calanus finmarchicus is broadly distributed in the North Atlantic, where it dominates the spring zooplankton biomass of shelf ecosystems. Calanus finmarchicus diapauses in the deep basins of the Gulf of Maine (GOM) during late-summer through early-winter. During diapause, predators that co-occur in regions of high copepod abundance may reduce survivorship through predation. Consequently it is important to measure the distribution patterns of C. finmarchicus and its predators. Two cruises were carried out during December of 1998 and 1999 in the GOM. Video Plankton Recorder (VPR) data collected in Wilkinson, Jordan and Georges Basins were used to describe …

Applying The Isotope Pairing Technique To Evaluate How Water Temperature And Habitat Type Influence Denitrification Estimates In Breton Sound, Louisiana, Peter L. Lenaker

LSU Master's Theses

The upper Breton Sound estuary was hydrologically reconnected to the Mississippi River via the Caernarvon freshwater diversion structure in 1991. The Caernarvon structure can provide controlled freshwater pulses to the upper Breton Sound estuarine ecosystem, replicating historic freshwater pulsed events, although the original authorization was to control salinity isohalines at specific locations in the estuary. However, unlike historic freshwater pulsed events prior to the construction of levees, the current freshwater pulse contains an unprecedented amount of inorganic nitrogen, predominately as nitrate (annual average 71.4 µM NO3-). Denitrification is a microbial process, which can potentially remove excess nitrate entering coastal Louisiana …

Neurotoxin In A Louisiana Estuary: Quantitative Analysis Of Domoic Acid In Gulf Menhaden (Brevoortia Patronus) And Qualitative Modeling Of Links In A Shark Nursery, Ross Del Rio

LSU Master's Theses

Harmful algal blooms are an increasing problem for coastal waters world-wide. The diatom genus, Pseudo-nitzschia, is of particular concern in Louisiana, due to the potential for several species to produce the neurotoxin domoic acid (DA). While trophic transfer of DA to consumers has repeatedly occurred along the California coast, little is known about trophic transfer of recently detected DA in the Gulf of Mexico. In this study, the presence of DA in gulf menhaden (Brevoortia patronus) and the potential for trophic transfer to higher order consumers was investigated. In addition, the effects of this transfer and other algal toxins that …

Modeling Gag Grouper (Mycteroperca Microlepis) In The Gulf Of Mexico: Exploring The Impact Of Marine Reserves On The Population Dynamics Of A Protogynous Grouper, Robert D. Ellis

LSU Master's Theses

The gag grouper (Mycteroperca microlepis) population in the Gulf of Mexico supports both a commercial and recreational fishery but has experienced a decrease in the male to female sex ratio over the past thirty years. Protogynous fish populations naturally have a smaller male to female ratio than gonochoristic fish populations; however the decline in the gag population is such that sperm limitation may be occurring. In an effort to correct the decline in sex ratio, fishery managers have recently implemented two marine reserves designed specifically to protect gag spawning aggregations. Results from two population models (an age-structured model and an …

Hydrodynamic Response To Cold Fronts Along The Louisiana Coast, Zhixuan Feng

LSU Master's Theses

Cold fronts play important roles in flushing water out of the Louisiana estuaries. This study is aimed at examining the impact of cold front passages on the hydrodynamics in autumn-winter-spring of 2006-2007, and tries to determine the geographic difference, correlation and relative importance of winds, tides, and river discharge on water level variability and flow field. The amplitude spectra of water level reveal that diurnal tides dominate most stations. Areas west of 91°W have relatively high semidiurnal tides. The subtidal fluctuations are mainly wind-driven. Only the station in the Atchafalaya River shows obvious response to the spring flood of the …

Seasonal Variability In Absorption And Fluorescence Properties Of Chromophoric Dissolved Organic Matter In The Barataria Basin, Louisiana, Usa, Shatrughan Singh

LSU Master's Theses

Absorption and fluorescence measurements of chromophoric dissolved organic matter (CDOM) were examined along a transect containing 36 sampling stations in the Barataria Basin during high and low conditions to observe seasonal variation in these optical properties. The objectives of this study were (i) to observe CDOM variability in Barataria Basin in variable flow (high and low) conditions, and to characterize the CDOM, (ii) to identify the constituents of CDOM and to model CDOM compositional variability in the Barataria Basin using parallel factor analysis (PARAFAC). CDOM–salinity relationships were non-conservative in lower and upper part of the transect; however a conservative inverse …

Cbod₅ Treatment And Nitrogen Transformations Of The Marshland Upwelling System In Intermediate And Saltwater Marshes, Lorna Anne Putnam

LSU Doctoral Dissertations

The marshland upwelling system (MUS) was designed to treat domestic wastewater from coastal dwellings where conventional methods are inadequate due to high water tables, poor hydraulic soil conditions, anaerobic soils, and saline groundwater. Currently there is no adequate treatment system available and coastal dwellings are contributing to water quality problems. This study focused on determining the treatment effectiveness of the MUS for organic matter and understanding the specific processes involved in nitrogen treatment.

The treatment of organic matter, measured as five-day carbonaceous biological oxygen demand (CBOD₅), was effective in field tests for both saltwater and intermediate marshes. Global …

Remediating Impacts Of Global Climate Change-Induced Submergence On Salt Marsh Ecosystem Functions, Camille Lafosse Stagg

LSU Doctoral Dissertations

Impacts of global climate change, such as sea level rise and severe drought, have altered the hydrology of coastal salt marshes resulting in submergence and subsequent degradation of ecosystem function. A potential method of rehabilitating these systems is the addition of sediment-slurries to increase the elevation of the marsh surface, thus ameliorating the effects of excessive inundation. Although this technique is growing in popularity, the successful restoration of ecological function after sediment addition has received little attention. The purpose of this research was to determine if sediment subsidized salt marshes are functionally equivalent to natural marshes and whether salt marshes …

Sedimentation On A Mixed Siliciclastic/Carbonate Continental Margin Over Decadal To Millennial Timescales: Gulf Of Papua, Zahid Muhammad

LSU Doctoral Dissertations

Sediments from the Gulf of Papua were examined to estimate particle flux and sediment mass accumulation rates on multiple timescales. Patterns of sediment mass accumulation and inventory-derived 210Pb fluxes display regional variations, decreasing seaward, and along isobaths seaward from the northeastern shelf edge. The amount of terrigenous sediment load being discharged annually from the shelf and accumulating in Pandora Trough is approximately 7-14×106 tonnes. The existence of possible turbidity-current transport and deposition have been documented in deeper parts of the Gulf of Papua. High excess 210Pb fluxes estimated from seabed inventories at the shelf edge and upper slope are consistent …

Subaqueous, Hurricane-Initiated Shelf Failure Morphodynamics Along The Mississippi River Delta Front, North-Central Gulf Of Mexico, Walter Scott Guidroz

LSU Doctoral Dissertations

Seafloor instability along the Mississippi River Delta Front (MRDF) gained renewed attention with the landfall of Hurricanes Ivan (2004) and Katrina (2005). Traditional root causes for MRDF shelf failure were exacerbated by sea-state conditions associated with these severe tropical cyclones and their interaction with the seafloor. These conditions were characterized by large waves, long wave periods and wave-induced turbulence in the bottom boundary layer and throughout the water column. An evaluation of local and regional MRDF bathymetry data revealed substantial changes in seafloor elevation and the immediate subsurface sediment profile, hypothesized as the end result of cyclic wave-seafloor interaction, seafloor …

The Role Of Climate Variability And Riverine Pulsing In The Community Dynamics Of Estuarine Nekton In Breton Sound, Louisiana, Bryan Patrick Piazza

LSU Doctoral Dissertations

Climate controls biotic community composition at multiple spatiotemporal scales through variability in environmental control mechanisms (assembly filters). This research investigated the role of climate variability in the community dynamics of estuarine nekton in Breton Sound estuary, Louisiana, and, specifically the effects of El Niño Southern Oscillation (ENSO), freshwater discharge, and a tropical cyclone. A teleconnection was found between ENSO and juvenile brown shrimp (Farfantepenaeus aztecus) abundance in Breton Sound from 1988 – 2007. ENSO affected winter weather conditions (air pressure, temperature and precipitation), and spring brown shrimp abundance in Breton Sound. Juvenile brown shrimp abundance lagged ENSO by …

Oil Platforms And Red Snapper Movement And Behavior, Michael Mcdonough

LSU Master's Theses

Understanding the behavior, including movement, of red snapper (Lutjanus campechanus), around and among the many oil and gas platforms in the northern Gulf of Mexico (GOM) is crucial to the management of this important commercial and recreational species. What role oil and gas production platforms play in the attraction vs. production continuum for red snapper is unknown, but it is certain these large structures have a role at some life history stage. We used the VRAP acoustic telemetry system to track red snapper around two platforms in the GOM in 2005 and 2006. Fish detections per hour generally decreased over …

Anthropogenic And Natural Perturbations On Lower Barataria Bay, Louisiana: Detecting Responses Of Marsh-Edge Fishes And Decapod Crustaceans, Agatha-Marie Fuller Roth

LSU Doctoral Dissertations

Barataria Bay, Louisiana is a dynamic estuary with ongoing disturbances that is in need of restoration. Development and validation of a lower Barataria Bay index of biotic integrity (IBI) for the summer season was the focus of my research. This IBI was created using 2005 data and evaluated with 2006 and 2007 data to demonstrate the feasibility of this approach in coastal Louisiana. The IBI successfully distinguished sites with differing levels of degradation using nine fish metrics. While pursuing this effort, two serendipitous events occurred when an oil spill then a hurricane impacted the study area. This gave me opportunities …

Comparisons Of Boosted Regression Tree, Glm And Gam Performance In The Standardization Of Yellowfin Tuna Catch-Rate Data From The Gulf Of Mexico Lonline [Sic] Fishery, Shane Abeare

LSU Master's Theses

Recent advances in statistical understanding have focused fisheries research attention on addressing the theoretical and statistical issues encountered in standardizing catch-rate data. Similarly, the present study evaluates the performance of boosted regression trees (BRT), the product of recent progress in machine learning technology, as a potential tool for catch-rate standardization. The BRT method provides a number of advantages over the traditional GLM and GAM approaches including, but not limited to: robust parameter estimates as a result of the integrated stochastic gradient boosting algorithm; model structure learned from data and not determined a priori, thereby avoiding assumptions required for model specification; …