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Full-Text Articles in Physical Sciences and Mathematics
Fishes Associated With Oil And Gas Platforms In Louisiana's River-Influenced Nearshore Waters, Ryan Thomas Munnelly
Fishes Associated With Oil And Gas Platforms In Louisiana's River-Influenced Nearshore Waters, Ryan Thomas Munnelly
LSU Master's Theses
A distinctive feature of coastal Louisiana is the unrivaled network of oil and gas installations (platforms) extending from inshore waters to the deep Gulf of Mexico. Since 2007 there has been a 38% reduction in platform numbers with the highest removal rates occurring in shallow (< 18 m) nearshore waters. Many fishes and invertebrates are attracted to platforms, presenting a unique opportunity to study detailed species-specific responses to the river-influenced hydrographic characteristics of Louisiana’s nearshore zone (5–25 km water depth). Prior studies of fishes around platforms focused on a few relatively large platforms in water depths ≥ 18 m. However, about one-third of all platforms are small, unmanned and non-drilling platforms located in waters < 18 m depth. Paired video and hydrographic data were collected at 150 small platforms in < 18 m water depth during the summers of 2013–2014. Fifty-four species of fishes were associated with small platforms. The assemblage(s) included juveniles of 29 species, indicating the importance of nearshore platforms as diverse nursery habitat. The coastal zone was divided into three regions based on broad-scale interactions between freshwater input and bathymetry driving major distinctions in interregional hydrography and fish assemblages. Co-occurring within this expansive artificial reef network is the second largest hypoxic area (dissolved oxygen (DO) < 2.0 mg l−1) on Earth. Platforms offer reef-like habitat features in the upper water column that may offer refugia for some reef-associated species during hypoxic events. Significant intraregional differences in physicochemical features were related to the presence of hypoxia (defined as DO < 50% saturation), as well as the distribution of sandy shoals. Eleven species accounted for most of the assemblage dissimilarities, composing ~93% of fishes observed. Habitat suitability indices for these 11 species provided information about habitat selection across horizontal and vertical physicochemical gradients throughout the coastal zone, and within hypoxic and well-oxygenated stratified water columns. East Bay, near the outlet of the Mississippi River, exhibited less hypoxia and a distinct fauna that included four adult goliath grouper (Epinephelus itajara). This endangered fish was observed during spawning season (summer), suggesting that East Bay might support a spawning aggregation.
Factors Influencing Mottled Duck Nest Success On The Atchafalaya River Delta, Brendan Caillouet
Factors Influencing Mottled Duck Nest Success On The Atchafalaya River Delta, Brendan Caillouet
LSU Master's Theses
The Atchafalaya River Delta system along with the Wax Lake Outlet Delta and the Mississippi River Delta are the only three areas in Louisiana where land is being gained. Beneficial use of dredge spoil from shipping channel maintenance is used on the Atchafalaya River Delta to supplement natural accretion. These dredge spoil islands have the ability to provide valuable nesting habitat for a variety of waterbirds, including Mottled Ducks. Previous studies on these islands reported mammalian predation to be a significant cause of nest failure for Mottled Ducks. I tested the hypothesis that predator reduction through trapping would increase Mottled …
Long-Term Total Suspended Sediment Yield Of Coastal Louisiana Rivers With Spatiotemporal Analysis Of The Atchafalaya River Basin And Delta Complex, Timothy Rosen
LSU Master's Theses
The modern day Mississippi River Delta Plain and the Louisiana Chenier Plain have been greatly altered through anthropogenic changes to course and hydrological conditions of the Mississippi River and local rivers, most notably by levees that have excluded the Mississippi River from the delta plain. This has slowed accretion and increased land loss destroying vast quantities of marsh, endangering many coastal communities. This master’s thesis examined long-term total suspended sediment yield of four Chenier Plain rivers, total suspended sediment yield of the Mississippi River under different flow conditions, and total suspended sediment dynamics of the Atchafalaya River in relation to …
Speciation Of Heavy Metals In Disturbed And Undisturbed Sediments From Atchafalaya Bay, Houma Navigation Canal, And Southwest Pass, Louisiana, Amanda Jo Zimmerman
Speciation Of Heavy Metals In Disturbed And Undisturbed Sediments From Atchafalaya Bay, Houma Navigation Canal, And Southwest Pass, Louisiana, Amanda Jo Zimmerman
LSU Master's Theses
In coastal Louisiana it is common to use dredge spoil to build marshland that has been lost due to a variety of factors. Under various conditions such as deposition in a drained oxygenated environment, metals in the spoil can become more bioavailable posing a threat to the ecosystem. This study compares metal availability in natural and dredged sediments to determine what changes occur in nature. Forty four samples from three locations, Atchafalaya Delta, Houma Navigation Canal, and Southwest Pass, were analyzed for 13 common elements with known or potentially harmful health effects; Al, As, Ba, Be, Cd, Cr, Co, Cu, …
Water And Solute Transport In The Shallow Subsurface Of A Riverine Wetland Natural Levee, April Elea Newman
Water And Solute Transport In The Shallow Subsurface Of A Riverine Wetland Natural Levee, April Elea Newman
LSU Master's Theses
In riverine wetlands, the rate and magnitude of water exchanged between river channels and adjacent wetlands have a major influence on hydrologic function and associated aquatic habitat and water quality. River channels are generally separated from backswamps by natural levees; however, preferential flow may allow potentially substantial water and solute exchange between them. Determining the influence of preferential flow on water and solute transport in natural levees requires an innovative approach that allows measurement of transport rates at a scale large enough to capture field-scale variability. To test the hypothesis that preferential flow is important to subsurface water movement through …
Sediment Transport On A River-Dominated Shallow Water Shelf: Atchafalaya Bay Region, Louisiana, Renee T. Bellotte
Sediment Transport On A River-Dominated Shallow Water Shelf: Atchafalaya Bay Region, Louisiana, Renee T. Bellotte
LSU Master's Theses
Cold front passage impacts on sediment transport on the inner continental shelf near Atchafalaya Bay were studied, combining satellite imagery and in-situ meteorological and oceanographic measurements. An empirical model relating atmospherically corrected MODIS imagery reflectance to surface measurements of suspended sediment concentration was developed and successfully applied to the coastal waters. An equation for predicting total suspended sediment from Nephelometric Turbidity Units was also applied to the water column at 1, 2, and 3 meters from the seabed. Five case study weeks were selected to examine the dynamics of pre-frontal and post-front forcing mechanisms on sediment transport in a fine-grained …
Distributary Mouth Bar Formation And Channel Bifurcation In The Wax Lake Delta, Atchafalaya Bay, Louisiana, Anton J. Dumars
Distributary Mouth Bar Formation And Channel Bifurcation In The Wax Lake Delta, Atchafalaya Bay, Louisiana, Anton J. Dumars
LSU Master's Theses
The Mississippi River has undergone at least seven cyclic avulsions during the Holocene epoch. The latest avulsion, down the Atchafalaya River into the Gulf of Mexico, has produced two bayhead deltas prograding into Atchafalaya Bay. The Wax Lake Delta, typical of other Mississippi sub-deltas, has a natural anastomosing channel pattern. In contrast, the Atchafalaya Delta, situated in the eastern side of the Bay, has experienced sporadic and limited growth due to the dredging of a navigation channel below natural depth. Channel bifurcation, and sediment transport processes and responses, were investigated in the Wax Lake Delta, using channel flow velocities, suspended …