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Full-Text Articles in Physical Sciences and Mathematics

Plankton Community Respiration And Productivity For The Louisiana Offshore Ecosystem, July 2007 Results, Brandon Michael Boyd Oct 2010

Plankton Community Respiration And Productivity For The Louisiana Offshore Ecosystem, July 2007 Results, Brandon Michael Boyd

Honors Theses

No abstract provided.


Beneath The Salt Marsh Canopy: Loss Of Soil Strength With Increasing Nutrient Loads, R. Eugene Turner Sep 2010

Beneath The Salt Marsh Canopy: Loss Of Soil Strength With Increasing Nutrient Loads, R. Eugene Turner

Faculty Publications

Although the broadly observed increase in nutrient loading rates to coastal waters in the last 100 years may increase aboveground biomass, it also tends to increase soil metabolism and lower root and rhizome biomass—responses that can compromise soil strength. Fourteen different multiyear field combinations of nutrient amendments to salt marshes were made to determine the relationship between soil strength and various nitrogen, phosphorus, and nitrogen+phosphorus loadings. There was a proportional decline in soil strength that reached 35% in the 60- to 100-cm soil layer at the highest loadings and did not level off. These loading rates are equivalent to those …


Abundance And Ecological Significance Of The Clam Rangia Cuneata (Sowerby, 1831) In The Upper Barataria Estuary (Louisiana, Usa), Wai Hing Wong, Nancy N. Rabalais, R. Eugene Turner Jun 2010

Abundance And Ecological Significance Of The Clam Rangia Cuneata (Sowerby, 1831) In The Upper Barataria Estuary (Louisiana, Usa), Wai Hing Wong, Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

We proposed that Rangia cuneata (Sowerby, 1831) is an important estuarine bivalve with ecological significance in three coastal lakes in Barataria Bay, Gulf of Mexico—Lake Cataouatche, Lake Salvador and Lac des Allemands. Our goals were to determine the abundance and distribution of Rangia in these lakes and to measure clearance times to elucidate its potential impacts on phytoplankton communities. The estimated average densities of R. cuneata in Lake Cataouatche, Lake Salvador, and Lac des Allemands were 63, 157, and 107 individuals m−2, respectively, which is 30% lower than that observed in nearby Lake Pontchartrain. The size of clams in Lake …


Patterns Of Habitat Suitability And Abundance Trends Of Current And Candidate Coastal Fish Species Of Concern In Louisiana, Elin Rose Sandy Jan 2010

Patterns Of Habitat Suitability And Abundance Trends Of Current And Candidate Coastal Fish Species Of Concern In Louisiana, Elin Rose Sandy

LSU Master's Theses

Louisiana’s estuaries and coastal waters play an important role in providing habitat for several estuarine-dependent species and also serve as a nursery for the juveniles of several other species. The current rate of land loss in Louisiana and the decline of estuarine-dependent species force us to improve our understanding of the recruitment of these species into Louisiana’s estuaries. Habitat suitabilities were developed for several fish species of concern (SOC) and other estuarine-dependent species across three environmental gradients, abundance patterns were developed for seasons, five-year intervals, and coastal study areas (CSAs). Chi-square analyses and ANOVAs were then used to test for …


The Effects Of Salinity On Nitrogen Cycling In Wetland Soils And Sediments Of The Breton Sound Estuary, La, Brett Whitfield Marks Jan 2010

The Effects Of Salinity On Nitrogen Cycling In Wetland Soils And Sediments Of The Breton Sound Estuary, La, Brett Whitfield Marks

LSU Master's Theses

Wetlands in the coastal zone are slowly becoming more saline under rising sea level over the long-term. However, there are a number of events in the coastal environment which lead to quick and temporary changes in the salinity of coastal marshes. Seawater driven inland from storm surge can significantly increase salinity in oligohaline wetlands over the short-term (weeks). Recent large-scale efforts to restore coastal wetlands in Louisiana have utilized Mississippi River surface water diversions to re-introduce freshwater into coastal marshes, decreasing the salinity of coastal marshes. We examined the effect of salinity changes on two important nitrogen cycling processes, potential …


Modeling The Impacts Of Pulsed Riverine Inflows On Hydrodynamics And Water Quality In The Barataria Bay Estuary, Anindita Das Jan 2010

Modeling The Impacts Of Pulsed Riverine Inflows On Hydrodynamics And Water Quality In The Barataria Bay Estuary, Anindita Das

LSU Doctoral Dissertations

Eutrophication and coastal wetland loss are the major environmental problems affecting estuaries around the world. In Louisiana, controlled diversions of the Mississippi River water back into coastal wetlands are thought to be an important engineering solution that could reverse coastal land loss. There are concerns, however, that freshwater diversions may increase nutrient inputs and create severe eutrophication problems in estuaries and wetlands adjacent to the diversion sites. My dissertation research concerns modeling the effects of the observed and hypothetical freshwater diversion discharges on the hydrodynamics, salinity and water quality in the Barataria estuary, a deltaic estuary in south Louisiana. This …


Landscape Patterns Of Community Structure, Biomass And Net Primary Productivity Of Mangrove Forests In The Florida Coastal Everglades As A Function Of Resource, Regulators, Hydroperiod, And Hurricane Distrubance, Edward Castaneda Jan 2010

Landscape Patterns Of Community Structure, Biomass And Net Primary Productivity Of Mangrove Forests In The Florida Coastal Everglades As A Function Of Resource, Regulators, Hydroperiod, And Hurricane Distrubance, Edward Castaneda

LSU Doctoral Dissertations

Spatial and temporal patterns of mangrove vegetation in the Florida Coastal Everglades (FCE) reflect a major interplay of resources, regulators and hydroperiod gradients. I investigated landscape patterns of community structure, biomass and NPP of mangroves along two FCE estuaries: Shark River and Taylor River. I also evaluated whether pulsing events such as Hurricane Wilma are significant to soil nutrient inventories and vertical accretion of mangroves in FCE. There was a higher forest structural complexity of mangroves in Shark River relative to Taylor River. The biomass root:shoot ratio was 17 times higher in Taylor River relative to Shark River, indicating that …


Geological Analysis And Hydrodynamic Modeling Of Tropical Cyclone Influence: Northeastern Gulf Of Mexico Inner Shelf, Amy Lynn Spaziani Jan 2010

Geological Analysis And Hydrodynamic Modeling Of Tropical Cyclone Influence: Northeastern Gulf Of Mexico Inner Shelf, Amy Lynn Spaziani

LSU Master's Theses

The need to characterize offshore resources as borrow areas for beach restoration has initiated interest of the impact of storms to the inner continental shelf. While numerous studies have investigated the response of coastal systems to major storms, very little is known about the geological response of inner shelves to frequent and intense storms. This approach integrated a geological study with modeling of hydrodynamics during recent storms, in order to relate trends in the geological signature to physical forcing mechanisms during storms. First, waves and hydrodynamic conditions were modeled during two major recent storms that made landfall in the northeastern …


The Effects Of A Freshwater Diversion Of Nekton Species Biomass Distributions, Food Web Pathways, And Community Structure In A Louisiana Estuary, Kim De Mutsert Jan 2010

The Effects Of A Freshwater Diversion Of Nekton Species Biomass Distributions, Food Web Pathways, And Community Structure In A Louisiana Estuary, Kim De Mutsert

LSU Doctoral Dissertations

A current method to restore Louisiana’s estuaries includes reintroducing freshwater and sediments to wetlands that are hydrologically isolated from the Mississippi River due to the construction of levees. In this dissertation, I examined effects of the second largest freshwater diversion in Louisiana, the Caernarvon Freshwater Diversion (CFD), on estuarine nekton in Breton Sound. Before focusing on Breton Sound, I examined the status of nekton communities in the northern Gulf of Mexico (GOM), and Louisiana wetlands in particular, using the mean trophic level index (MTLI). I demonstrated that commercial targeting caused the previously reported low and declining MTLI from the GOM. …


Edaphic And Vegetative Controls On Mercury Cycling In Oligohaline Wetlands, Jonathan M. Willis Jan 2010

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 …


Pharmaceutical Compounds In Treatment Wetlands: Potential Removal And Effects On Microbial Processes, Jeremy Landon Conkle Jan 2010

Pharmaceutical Compounds In Treatment Wetlands: Potential Removal And Effects On Microbial Processes, Jeremy Landon Conkle

LSU Doctoral Dissertations

active compounds (PhACs) have been detected in the aquatic environment as a result of loading from various sources. In Louisiana, USA, many municipalities treat wastewater using natural systems, such as lagoons and wetlands, rather than using conventional wastewater treatment technologies and may discharge PhACs into the environment. These treatment systems are not designed to remove PhACs from wastewater, nor is it currently a regulatory requirement. Research on the fate of PhACs in the environment is needed to understand impacts on Louisiana’s important coastal system. Wastewater sampling for PhACs at the Mandeville, LA wastewater treatment plant (WWTP) determined that this system …


Integration Of Paleotempestology With Coastal Risk And Vulnerability Assessment: Case Studies From The Dominican Republic And Nicaragua, Devyani Kar Jan 2010

Integration Of Paleotempestology With Coastal Risk And Vulnerability Assessment: Case Studies From The Dominican Republic And Nicaragua, Devyani Kar

LSU Doctoral Dissertations

Hurricanes account for a significant portion of damages, injuries, and fatalities in the Caribbean. The Dominican Republic has had 3 major hurricane strikes in this century resulting in loss of lives for thousands of people and billions of US $ in economic loss. Major hurricanes had been relatively infrequent in north-eastern Nicaragua’s modern history until Hurricane Felix, a Category 5 storm, made landfall in the north-east in 2007. It caused 130 confirmed deaths and brought devastation to many villages. These events highlight a need for re-evaluation of hurricane risk based on a more comprehensive and long-term hurricane history. Using paleotempestological …


Analysis And Modeling Of Hurricane Impacts On A Coastal Louisiana Lake Bottom, Angelina Freeman Jan 2010

Analysis And Modeling Of Hurricane Impacts On A Coastal Louisiana Lake Bottom, Angelina Freeman

LSU Doctoral Dissertations

Tropical cyclone impacts on wetland, terrestrial, and shelf systems have been previously studied and reasonably delineated, but little is known about the response of coastal lakes to storm events. For the first time, tropical cyclone impacts on a shallow coastal lake in the Louisiana coastal plain have been studied using direct lines of evidence and numerical modeling. Using side-scan sonar, CHIRP subbottom and echo sounder bathymetric profiles, the lake bottom and shallow subsurface of Sister Lake was imaged pre- and post-Hurricanes Katrina and Rita to provide a geologic framework for assessing the effects of these storms. Box cores were collected …


Estuarine Phytoplankton Response To Annual And Manipulated River Inputs, Jessica Czubakowski Jan 2010

Estuarine Phytoplankton Response To Annual And Manipulated River Inputs, Jessica Czubakowski

LSU Master's Theses

River water entering estuaries affects the physical and chemical environment at irregular intervals creating a highly dynamic aquatic habitat. Phytoplankton are important primary producers in estuaries that respond quickly to their changing environment. Since 1991, Breton Sound estuary in southeast Louisiana has been directly influenced by Mississippi River water through the Caernarvon Freshwater Diversion structure. Over a 12 month period, the phytoplankton response was examined, in terms of biomass, abundance, community composition and potential phycotoxin production to seasonal changes in river input into the estuary. Within this 12 month period, a short pulse study was also carried out to examine …


Physical And Microbial Responses Of Dredged Sediment To Two-Soil-Stabilizing Amendments, Xanthan Gum And Guar Gum, For Use In Coastal Wetland Restoration, Lauren Land Jan 2010

Physical And Microbial Responses Of Dredged Sediment To Two-Soil-Stabilizing Amendments, Xanthan Gum And Guar Gum, For Use In Coastal Wetland Restoration, Lauren Land

LSU Master's Theses

In wetland sediments, organic matter provides a substrate for microbial activity. During metabolism, microbes release extracellular polymeric substances, which accumulate to bind soil particles. A similar concept can be implemented on a large scale to reduce wetland loss in Louisiana. Hypothetically, hydraulically dredged sediment can be amended with polymer and deposited on subsiding marshes as a restoration method where the polymer increases sediment stabilization until plants become established. This lab study focused on investigating the influence of natural polymer additions on particle aggregation to increase sediment stability and the effects on microbial activity. Sediments from three sites (i.e. freshwater, intermediate, …


Hepatotoxic Cyanobacterial Blooms In Louisiana's Estuaries: Analysis Of Risk To Blue Crab (Callinectes Sapidus) Following Exposure To Microcystins, Ana Cristina Garcia Jan 2010

Hepatotoxic Cyanobacterial Blooms In Louisiana's Estuaries: Analysis Of Risk To Blue Crab (Callinectes Sapidus) Following Exposure To Microcystins, Ana Cristina Garcia

LSU Master's Theses

The most common toxins detected following freshwater harmful algal blooms are microcystins, a group of hepatotoxins produced by cyanobacteria (e.g., Microcystis and Anabaena spp.). Preference for filter-feeding prey, including bivalves, makes the blue crab, Callinectes sapidus, vulnerable to microcystin contamination and makes the commercially important crab a potential vector of microcystins. I used a combination of field and laboratory studies to determine blue crab vulnerability to microcystin contamination and consequent impacts on crab physiology. Samples collected from a hyper-eutrophic freshwater lake, Lac des Allemands, Louisiana, were analyzed for cyanobacterial abundances and microcystins in surface water and blue crabs using light-microscopy …