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Louisiana State University

Oceanography and Atmospheric Sciences and Meteorology

2002

Articles 1 - 12 of 12

Full-Text Articles in Physical Sciences and Mathematics

Nitrogen Loading Into An Urban Estuary: Lake Pontchartrain (Louisiana, U.S.A.), R. Eugene Turner, Q. Dortch, Dubravko Justic, Erick M. Swenson Nov 2002

Nitrogen Loading Into An Urban Estuary: Lake Pontchartrain (Louisiana, U.S.A.), R. Eugene Turner, Q. Dortch, Dubravko Justic, Erick M. Swenson

Faculty Publications

We constructed a nitrogen loading budget for the Lake Pontchartrain watershed located north of New Orleans, Louisiana (U.S.A.). Water quality measurements, discharge estimates, and literature values were used to establish the annual and seasonal variations in loading rates for total nitrogen and nitrate. The relatively stable annual loadings (million kg N) are about 10× that of the pre-settlement nitrogen loading, and come from atmosphere (1.3), the watershed (7.8), pumped urban runoff from New Orleans (1.0), and leakage through the Bonnet Carré flood control structure (0.5–0.9). Relatively minor additional amounts come from nitrogen fixation in the Lake. Occasional openings of the …

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Denitrification Potential Of Sediment From A Future Mississippi River Diversion Site In Louisiana, Roy Ryuta Iwai Jan 2002

Denitrification Potential Of Sediment From A Future Mississippi River Diversion Site In Louisiana, Roy Ryuta Iwai

LSU Master's Theses

Denitrification potential was determined in surface sediment from Lake Cataouatche, the receiving basin for a future Mississippi River diversion located in the northern portion of the Barataria Basin estuary. Nitrate removal and denitrification was measured in the laboratory using static sediment microcosms flooded with lake water. Dissolved potassium nitrate (KNO3) was added to the microcosms to achieve: 1) an initial nitrate concentration similar to the mean Mississippi River concentration (~1.4 mg NO3-N l-1), and, 2) a high initial nitrate concentration to elicit a denitrification potential (~50 mg NO3-N l-1). Denitrification …

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The Effects Of Fall Coldfront Passages On The Nekton Community In A Tidal Creek In Port Fourchon, La, As Monitored By Hydroacoustics, David J. Harmon Jan 2002

The Effects Of Fall Coldfront Passages On The Nekton Community In A Tidal Creek In Port Fourchon, La, As Monitored By Hydroacoustics, David J. Harmon

LSU Master's Theses

Split-beam hydroacoustic sampling with two, 420 KHz, 2x6 degree elliptical transducers was evaluated as a tool to quantify nekton movements in a Louisiana estuary. I measured the effects of atmospheric cold front passages on nekton in a tidal creek in Port Fourchon, LA during the fall of 2000. Six “fronts” were sampled between October 6 and December 18, 2000. Nekton density ranged from 0 to 24.4 fish/m3 with an overall mean of 2.44 fish/m3. Net samples were taken to supplement the acoustic data with species composition data. Species composition changed from October to December. A higher number …

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Feeding Habits Of Blacktip Sharks, Carcharhinus Limbatus, And Atlantic Sharpnose Sharks, Rhizoprionodon Terraenovae, In Louisiana Coastal Waters, Kevin Patrick Barry Jan 2002

Feeding Habits Of Blacktip Sharks, Carcharhinus Limbatus, And Atlantic Sharpnose Sharks, Rhizoprionodon Terraenovae, In Louisiana Coastal Waters, Kevin Patrick Barry

LSU Master's Theses

Little is known regarding the feeding behavior of many shark species. Even less is known about shark feeding habits in Louisiana coastal waters. The stomach contents of gillnet-captured blacktip sharks (n=356), Carcharhinus limbatus, and Atlantic sharpnose sharks (n=55), Rhizoprionodon terraenovae, were examined in this study. Roughly half of the blacktip stomachs (52%) and sharpnose stomachs (45%) contained prey items. The primary prey item in terms of percent number, occurrence, and weight for blacktips and sharpnose was the gulf menhaden, Brevoortia patronus. Both blacktips and sharpnose appear to mainly be piscivores; however, no members of Sciaenidae, the most common family of …

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Tidal Dynamics In The Bab El Mandab Strait, Ewa Jarosz Jan 2002

Tidal Dynamics In The Bab El Mandab Strait, Ewa Jarosz

LSU Doctoral Dissertations

The Bab el Mandab Strait is where the transition occurs between two noticeably different tidal regimes: the Gulf of Aden, where tidal fluctuations are mixed and have a range in excess of 2 m, and the Red Sea, where the tides are principally semidiurnal and their range is less than 1 m. Within the Strait, observations collected between May of 1995 and July of 1997 indicate that tidal currents are a mixed type and dominant constituents are the K1 and M2. The vertical structure of the tidal currents is complicated, differs between semidiurnal and diurnal constituents, and …

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Sedimentation Rates And Metal Retention In An Urban Louisiana Swamp, Renee Lynn Sanders Jan 2002

Sedimentation Rates And Metal Retention In An Urban Louisiana Swamp, Renee Lynn Sanders

LSU Master's Theses

Naturally vegetated areas converted to urban uses increases impervious surfaces in a watershed with corresponding increases in nutrient, sediment, and metal loadings to downstream ecosystems. Wetlands mitigate detrimental impacts by transforming or retaining pollutants. Current and historic sedimentation and metal retention rates were measured in an urban, depressional wetland in Baton Rouge, Louisiana to evaluate landscape position and watershed development on these processes. Sedimentation disks, feldspar marker horizons, and Cs137 analyses were used in three distinct landscape positions. Inflow channels had the highest elevation and water velocity while the interior was located in the lowest elevations with the longest hydroperiod. …

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Sediment Transport In Wind-Exposed Shallow, Vegetated Aquatic Systems, Allen Michael Teeter Jan 2002

Sediment Transport In Wind-Exposed Shallow, Vegetated Aquatic Systems, Allen Michael Teeter

LSU Doctoral Dissertations

Ecosystems with submersed vegetation are relatively shallow, physically stable and of moderate hydrodynamic energy. Submersed vegetation affect hydrodynamic friction for currents and waves resulting in increased overall frictional loss. Seagrasses shelter the sediment bed and reduce wind-wave resuspension. Bed sheltering factors were estimated from previous flume data on Laguna Madre seagrass species. Data from Laguna Madre indicate that total suspended material levels for bare areas are about an order of magnitude higher than some areas with submersed vegetation. Waves in Laguna Madre at depths less than 2 m were found to be smaller than those expected for the same non-dimensional …

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Ontogeny And Intervals Of Development In Five Reef-Associated Species Of Blenny From The Northern Gulf Of Mexico (Teleostei: Blenniidae), James G. Ditty Jan 2002

Ontogeny And Intervals Of Development In Five Reef-Associated Species Of Blenny From The Northern Gulf Of Mexico (Teleostei: Blenniidae), James G. Ditty

LSU Doctoral Dissertations

I examined patterns and timing of ontogeny and relative growth in five species of blenny (Teleostei: Blenniidae) from the northern Gulf of Mexico by assigning a suite of discrete character state scores to ontogenetic events (10 external traits; 218 total specimens). This is the first study to evaluate developmental patterns in reef-associated fishes relative to the timing of metamorphosis and settlement by applying scaling techniques and statistical methods to quantify, differentiate, and select criteria for defining intervals of development across taxa. Blennies settle at a common state of ontogeny and share a common pattern of body and fin/cirrus growth. Three …

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The Combined Effects Of Salinity And Sulfide On The Growth And Physiology Of The Freshwater Marsh Plant Pancium Hemitomon J.A. Schultes, James Wesley Pahl Jan 2002

The Combined Effects Of Salinity And Sulfide On The Growth And Physiology Of The Freshwater Marsh Plant Pancium Hemitomon J.A. Schultes, James Wesley Pahl

LSU Doctoral Dissertations

Vegetative response to saltwater intrusion into coastal freshwater wetlands is governed by the combined effects of increased salinity and porewater sulfide concentrations. I conducted a series of experiments to address the primary hypothesis that growth of Panicum hemitomon is adversely affected by an interaction between salinity and sulfide stresses associated with saltwater intrusion, and the mechanisms for decreased growth are alterations in the metabolic and morphological adaptations needed for a plant to survive in a flooded environment. I exposed marsh sods to a factorial treatment arrangement of three salinities (0, 2, and 4 ppt) and three porewater sulfide concentrations (0, …

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Hydrodynamics And Freshwater Diversion Within Barataria Basin, Dongho Park Jan 2002

Hydrodynamics And Freshwater Diversion Within Barataria Basin, Dongho Park

LSU Doctoral Dissertations

In order to understand the physical processes in the Barataria estuary, a previously developed two-dimensional, depth-integrated hydrodynamic model is applied to simulate estuarine processes. The equations for conservation of mass and momentum predict specific physical processes when forced by tidal and salinity variations at the open boundaries, wind forcing patterns, precipitation and evaporation over the model domain, and freshwater runoff as point sources. This study is focused on examining the impact of freshwater dispersion from the freshwater sources. Thus, a hydrologic model was developed to estimate runoff. Furthermore grid size was reduced, a new advective code added, and baroclinic effects …

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The Importance Of Zooplankton In The Diets Of Blue Runner (Caranx Crysos) Near Offshore Petroleum Platforms In The Northern Gulf Of Mexico, Sean Francis Keenan Jan 2002

The Importance Of Zooplankton In The Diets Of Blue Runner (Caranx Crysos) Near Offshore Petroleum Platforms In The Northern Gulf Of Mexico, Sean Francis Keenan

LSU Master's Theses

Blue runner (Caranx crysos), common around offshore petroleum platforms in the Gulf of Mexico, were found to forage extensively on meso- and macro-zooplankton during the summer months. Larval decapods and stomatopods, hyperiid amphipods, pteropods, and larval and juvenile fishes were common components of their diet. Feeding periodicity results suggest that blue runner around platforms were capable of feeding throughout the night at the same intensity as the day. Size selectivity indicated that larger prey, such as fish were consumed during the night and smaller decapod crustaceans were consumed during the day. Blue runner collected from open waters away from platforms …

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Scientific And Management Perspectives In Wetland Groundwater Hydrology, Lorna Veronica Inniss Jan 2002

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, …

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