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Louisiana State University

Oceanography and Atmospheric Sciences and Meteorology

2006

Articles 1 - 16 of 16

Full-Text Articles in Physical Sciences and Mathematics

Will Lowering Estuarine Salinity Increase Gulf Of Mexico Oyster Landings?, R. Eugene Turner Jun 2006

Will Lowering Estuarine Salinity Increase Gulf Of Mexico Oyster Landings?, R. Eugene Turner

Faculty Publications

Previous studies provide conflicting opinions on whether lower than average salinities in Gulf of Mexico (GOM) estuaries are likely to increase or decrease oyster harvests (Crassostrea virginica), which represented 69% and 54% of the United States oyster landings by weight, and dockside value, respectively, in 2003. The present study examined a 54-yr record (1950–2003) of oyster harvests and river discharge in five major estuaries in GOM states (Florida, Alabama, Mississippi, Louisiana, and Texas). Oyster landings were inversely related to freshwater inflow. Peaks in landings, 21 of 23 in West Florida, Alabama, Mississippi, and Texas combined, were coincidental with …

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Application Of Short-Term Sediment Dynamics And Particle-Bound Phosphorus Fractionation Methods (Sedex) To Estimate The Benthic Nutrient Loading Potential In Upper Newport Estuary, California, Hilary Amanda Collis Jan 2006

Application Of Short-Term Sediment Dynamics And Particle-Bound Phosphorus Fractionation Methods (Sedex) To Estimate The Benthic Nutrient Loading Potential In Upper Newport Estuary, California, Hilary Amanda Collis

LSU Master's Theses

Estuaries act as sources, sinks, and biogeochemical transformation sites for natural and anthropogenically-derived nutrients. Sediment loading from watersheds provides an important source of particulate nutrients to estuaries often neglected when constructing nutrient budgets. Deposition and resuspension of these sediments are known to impact biogeochemical cycles in estuarine environments. Phosphorus (P) exists in many forms in aquatic environments, and increased P loading to coastal environments increases primary productivity potentially leading to eutrophication. Magnitude and variability of sediment deposition, resuspension, and sediment-bound P concentrations were evaluated in Upper Newport Bay (UNB), California. During 2004, seven push cores were collected from the intertidal …

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Oxygen Depletion In The Gulf Of Mexico Adjacent To The Mississippi River, Nancy N. Rabalais, R. Eugene Turner Jan 2006

Oxygen Depletion In The Gulf Of Mexico Adjacent To The Mississippi River, Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

The seasonal formation of a bottom water layer severely depleted in dissolved oxygen has become a perennial occurrence on the Louisiana continental shelf adjacent to the Mississippi River system. Dramatic changes have occurred in this coastal ecosystem in the last half of the 20th century as the loads of dissolved inorganic nitrogen tripled. There are increases in primary production, shifts in phytoplankton community composition, changes in trophic interactions, and worsening severity of hypoxia. The hypoxic conditions (dissolved oxygen less than 2 mg l-1) cover up to 22,000 km2 of the seabed in mid-summer. Dissolved oxygen concentrations seldom decrease to anoxia, …

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A Community Approach To Identifying Essential Fish Habitat Of Spotted Seatrout, Cynoscion Nebulosus, In Barataria Bay, La, Pamela Sharon Dawn Macrae Jan 2006

A Community Approach To Identifying Essential Fish Habitat Of Spotted Seatrout, Cynoscion Nebulosus, In Barataria Bay, La, Pamela Sharon Dawn Macrae

LSU Doctoral Dissertations

Louisiana wetlands are disappearing at a dramatic rate, providing an impetus for identifying essential fish habitat (EFH) in this region. The distribution, relative abundance, biomass, length and food web dynamics of spotted seatrout, Cynoscion nebulosus, as well as the fish assemblage structure were examined in Barataria Bay, LA, in relation to habitat type and physical/chemical properties of the water. All fish were collected from three sites located along a salinity gradient, each contained the three habitat types of interest: marsh edge, soft bottom and oyster shell, and were sampled monthly from May 2003 to May 2004 with gillnets. Habitat preference …

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Nutrient Constraints On Plant Community Production And Organic Matter Accumulation Of Subtropical Floating Marshes, Guerry O., Jr. Holm Jr. Jan 2006

Nutrient Constraints On Plant Community Production And Organic Matter Accumulation Of Subtropical Floating Marshes, Guerry O., Jr. Holm Jr.

LSU Doctoral Dissertations

In the cycle of delta growth and decay, peat-forming wetlands span a time and space continuum. Later in the delta cycle, freshwater floating marshes become increasingly removed from external sediment subsidy and internal nutrient cycling controls plant productivity and organic matter accumulation. An interesting question is whether increased external nutrient loading can affect the basic processes that lead to peat formation—plant production and organic matter decomposition. I conducted several field studies to understand whether belowground organic matter accumulation and decomposition were affected with increased nutrient exposure; in addition, the plant community was monitored over three years. A laboratory soil respiration …

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Using Life-History, Surplus Production, And Individual-Based Population Models For Stock Assessment Of Data-Poor Stocks: An Application To Small Pelagic Fisheries Of The Lingayen Gulf, Philippines, Ronald B. Lachica Jan 2006

Using Life-History, Surplus Production, And Individual-Based Population Models For Stock Assessment Of Data-Poor Stocks: An Application To Small Pelagic Fisheries Of The Lingayen Gulf, Philippines, Ronald B. Lachica

LSU Master's Theses

Stock assessment methods that quantify the status of fishery resources are critical to effective fisheries management. There is a need for stock assessment methods applicable for management of tropical species based on limited, un-aged catch data. I applied four stock assessment approaches to situation with limited life-history information and with short-term, un-aged catch data. The four approaches are: life-history invariants, length-based catch analysis, individual-based modeling, and surplus production modeling. All four approaches were applied to catch data from Lingayen Gulf, Philippines. The life-history invariant, length-based catch analysis, and individual-based modeling were applied to monthly length-frequency data of commercial catch for …

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Habitat Use By Nekton In A Saltmarsh Estuary Along A Stream-Order Gradient In Northeastern Barataria Bay, Louisiana, Pablo Granados-Dieseldorff Jan 2006

Habitat Use By Nekton In A Saltmarsh Estuary Along A Stream-Order Gradient In Northeastern Barataria Bay, Louisiana, Pablo Granados-Dieseldorff

LSU Master's Theses

Mesohaline estuarine regions in Louisiana play an important role in coastal ecosystems. To begin to understand how nektonic species and communities respond to environmental variables before habitat modification, I examined patterns of habitat use by fishes and decapod crustaceans in a seemingly pristine mesohaline system that drains into Bay Batiste, southeastern Louisiana. The study area was focused on a relatively unaltered core saltmarsh complex drained by intertidal and subtidal streams and it was representative of a larger surrounding system in terms of nekton community structure and associated environmental variables. Stratified monthly sampling (February – November 2004) along a stream-order gradient …

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Modeling The Effects Of Endocrine Disrupting Chemicals On Atlantic Croaker: Understanding Biomarkers And Predicting Population Responses, Cheryl Anne Murphy Jan 2006

Modeling The Effects Of Endocrine Disrupting Chemicals On Atlantic Croaker: Understanding Biomarkers And Predicting Population Responses, Cheryl Anne Murphy

LSU Doctoral Dissertations

A number of environmental stressors have been shown to interfere with reproductive and behavioral processes of fish by interfering with endocrine function. Most biomarkers of endocrine disturbance tend to be static measurements from dynamic systems making them difficult to evaluate within the context of an individual, or subtle effects that do not relate well to endpoints of ecological significance. I present an approach that uses a series of models, based on Atlantic croaker, to extrapolate laboratory results to indicators of individual and population health. First, I created a physiologically based model that simulates vitellogenesis in a female fish. The model …

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Laboratory And Field Measurements Of Bioturbation By Macrofauna In A Coastal Setting, Skyler Neylon Jan 2006

Laboratory And Field Measurements Of Bioturbation By Macrofauna In A Coastal Setting, Skyler Neylon

LSU Master's Theses

Two ophiuroid species, Hemipholis elongata and Ophiophragmus spp. were studied in laboratory microcosms to elucidate patterns of sediment mixing for key bioturbators in the Mississippi Sound, Mississippi. The effects of bioturbation on artificially stratified sediments in microcosms were traced via time-series digital x-radiography. Preliminary results indicate that for three population densities of the brittle stars (comparable to field densities), a steady state volumetric bioturbation rate of 1-2 cm3/d is reached within two months of introduction to a fresh system. The preservation quotient, q, a fractional measure of preserved primary fabric, reached a minimum of 0.5 during the 16-week experiment. Maximum …

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Salt Marsh Restoration With Sediment-Slurry Amendments Following A Drought-Induced, Large-Scale Disturbance, Angela Marie Schrift Jan 2006

Salt Marsh Restoration With Sediment-Slurry Amendments Following A Drought-Induced, Large-Scale Disturbance, Angela Marie Schrift

LSU Master's Theses

A large-scale, drought-induced disturbance occurred in Louisiana during the spring and summer of 2000. Approximately 100,000 acres of Spartina dominated marshes died-back and turned brown. This die-off caused considerable concern because in the absence of recovery dieback marshes can transform to mudflats, which can subside leading to open ponds. The state of Louisiana is attempting to restore some of the dieback marshes through the addition of sediment-slurries. The sediment-slurry generated significantly different marsh elevations: high elevation (mean and 95 % confidence interval: 29, 26 to 32 cm above ambient marsh), medium elevation (21, 19 to 24 cm), low elevation (14, …

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Quantifying Changes In Fish Habitat Use In Coastal Waters Of Louisiana, Usa: A Hydroacoustic Approach, Kevin Mershon Boswell Jan 2006

Quantifying Changes In Fish Habitat Use In Coastal Waters Of Louisiana, Usa: A Hydroacoustic Approach, Kevin Mershon Boswell

LSU Doctoral Dissertations

The development of reliable tools for identifying essential fish habitat (EFH) has proven problematic. Knowledge of the distribution and biomass of fishes over discrete habitat types is a prerequisite for effective use of EFH in the management of important commercial and recreational fish species. Resolution of the influence of habitat type and environmental factors on the distribution of fishes is confounded by limitations of traditional sampling gears. To date, hydroacoustic technology has been widely accepted as a tool for surveying fishery resources; however few studies have implemented acoustics in ultra shallow (<2 m) coastal waters. Efforts should be made to utilize hydroacoustics for quantifying changes in fish distributions within estuarine environments given the benefits provided through acoustic technology (e.g. ease of deployment, reduced sampling effort, and non-invasive sampling attributes). A technique was developed for acoustically sensing fishes in the shallow, turbid waters of Barataria Bay, Louisiana. A robust and lightweight remotely-controlled transducer platform was designed for deploying acoustic gear. Sources of scattering within the bay were identified through a series of exclosure net experiments designed to quantify potential effects of plankton and suspended solids on acoustic scattering. Analysis filters were developed to reduce the effects of bubble-induced noise, often observed during periods when wind speeds were greater than 4.5 m s-1. Side-aspect acoustic target strength-length and target …

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A Neural Network Model For Classification Of Coastal Wetlands Vegetation Structure With Moderate Resolution Imaging Spectro-Radiometer (Modis) Data, Evaristo Joseph Liwa Jan 2006

A Neural Network Model For Classification Of Coastal Wetlands Vegetation Structure With Moderate Resolution Imaging Spectro-Radiometer (Modis) Data, Evaristo Joseph Liwa

LSU Doctoral Dissertations

Mapping coastal marshes is an important component in the management of coastal environments. Classification of marshes using remote sensing data has traditionally been performed by employing either parametric supervised classification algorithms or unsupervised classification algorithms. The implementation of these conversional classification methods is based on the underlying distributions concerning the probability density functions (PDF). Neural networks provide a practical approach to this classification because they are essentially non-parametric data transformations that are not restricted by any underlying assumptions. The major objective of this study was to evaluate the ability of neural networks using Moderate Resolution Imaging Spectro-radiometer (MODIS) data to …

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Petrological And Geochemical Investigations Of Deep Sea Turbidite Sands In The Pandora And Moresby Troughs: Source To Sink Papua New Guinea Focus Area, Luke Jeremiah Patterson Jan 2006

Petrological And Geochemical Investigations Of Deep Sea Turbidite Sands In The Pandora And Moresby Troughs: Source To Sink Papua New Guinea Focus Area, Luke Jeremiah Patterson

LSU Master's Theses

The Moresby and Pandora Troughs of the northern Coral Sea are components of the deep-sea depositional system that is the ultimate sink for the Source to Sink Papua New Guinea (PNG) Focus Area. Cores collected from the R/V Melville during March-April 2004 reveal marine volcaniclastic and terrigenous turbidites deposited in these troughs during the Quaternary. Constraining the spatial, temporal, and provenance characteristics for these terrigenous sands through mineralogical, chemical, and textural analysis is the primary focus of this study. All cores contain thinly-bedded sandy turbidite packages interlayered with hemipelagic marls and typical centimeter-to-meter-thick turbidite sequences. The Moresby Trough core JPC22 …

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Belowground Biomass Of Spartina Alterniflora: Seasonal Variability And Response To Nutrients, Faith Armand Darby Jan 2006

Belowground Biomass Of Spartina Alterniflora: Seasonal Variability And Response To Nutrients, Faith Armand Darby

LSU Doctoral Dissertations

Spartina alterniflora is a salt marsh macrophyte found from Canada to the Gulf of Mexico which often provides the dominant plant cover. Although S. alterniflora is well known for its high aboveground productivity, fifty to ninety percent of the total plant production occurs belowground. No previous studies address the seasonal variation of belowground biomass or the response of above-and belowground biomass to nutrients at the southern limits of its U. S. range. The objectives of this study were to: 1) document the seasonal variability of its above- and belowground biomass and test for responses to various combinations of N, P, …

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River, Tidal And Wind Interactions In A Deltaic Estuarine System, Gregg Snedden Jan 2006

River, Tidal And Wind Interactions In A Deltaic Estuarine System, Gregg Snedden

LSU Doctoral Dissertations

The balance between river and marine influences is important in governing landscape sustainability in river deltas. River- and atmospherically driven sea level variability, sediment loading, and estuary-ocean exchange in the Mississippi River delta are examined in this study. Subtidal estuarine sea level variability in the Breton Sound estuary was driven by a combination of remote atmospheric forcing outside the estuary over the continental shelf and controlled river inputs through a gated diversion structure at the estuary head. The highly-frictional deltaic landscape acted as a low-pass filter to coastal fluctuations near the estuary mouth. When substantial quantities river water were discharged …

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Effects Of Diesel-Fuel And Copper Contaminants On Benthic Microalgae, Soraya Silva Jan 2006

Effects Of Diesel-Fuel And Copper Contaminants On Benthic Microalgae, Soraya Silva

LSU Doctoral Dissertations

Salt marshes are dynamic, highly productive habitats and serve as nursery grounds for many commercially and economically important species. Benthic microalgae (BMA) are considered an important food source for benthos and provide the principal source of nutrition that fuels secondary production. Estuarine sediments around the world are a repository for many contaminants from anthropogenic sources. In particular, hydrocarbons and metals are ubiquitous contaminants in coastal systems. The primary goal of this study was to study the effects of diesel fuel and copper, alone and in combination, on the BMA assemblage from a coastal salt marsh. To achieve this objective, salt …

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