The armoring of river banks with riprap can have detrimental effects on lotic ecosystems due to the subsequent alteration of hydrologic regimes; however, evidence suggests that riprap can also increase aquatic diversity in degraded systems. The goal of my study was to determine what impacts riprapped banks have on fish and macroinvertebrate assemblages in the Pearl River, which has a history of anthropogenic degradation. I collected fishes with an electrofishing boat from armored and natural banks at five regions during fall 2011, winter 2012, and summer 2012. I also collected macroinvertebrates with introduced substrates in fall 2011. Richness was analyzed with rarefaction curves, whereas seasonal abundance and evenness were analyzed with ANOVA, and differences in assemblage structure were assessed with PERMANOVA. Fish and macroinvertebrate richness never varied between bank types. However, fish evenness and abundance were higher at riprapped banks during the summer, and fish assemblage composition varied during base flows in the summer and fall. Macroinvertebrate and assemblage structure also varied between bank types in the fall. My results imply that, at base flows, riprapped banks in the Pearl River support unique aquatic assemblages, possibly due to differences in heterogeneous habitat availability. On August 9, 2011 waste material from a paper mill in Bogalusa, LA was accidentally discharged into the Pearl River, causing anoxic conditions that resulted in complete fish extirpation downstream of the spills source. ANOVA indicated that, by October 2011, fish species richness and evenness at sites ~10 km downstream of the spill did not differ from sites in undisturbed areas, although richness and evenness at sites ~40 km downstream were still significantly lower at this time. However, by January, richness and evenness at all disturbed and undisturbed sites were similar. PERMANOVA indicated that, despite similarities in richness and evenness, fish assemblage composition at sites ~10 km downstream of the spill remained significantly different from undisturbed areas until January 2012, while sites ~40 km downstream of the spill were still significantly different by the studys end in July 2012. These results suggest a gradual recovery, with colonization rates related to the proximity of source populations.

Gopher tortoise (Gopherus polyphemus) populations have declined with longleaf pine (Pinus palustris) ecosystems across their historic range. The influence of gopher tortoise burrows on co-inhabiting plants and animals necessitates an understanding of how landscape features and management practices influence gopher tortoise presence, absence, and abandonment. In this study, naïve gopher tortoise burrow encounter rates from a line transect distance sampling (LTDS) pilot study were used for two methods of modeling gopher tortoise habitat. In Chapter 1, naïve encounter rates were tested for a linear correlation to a HSI model created from three ranked geographic information system (GIS) landscape variables. Initial results showed a positive linear correlation (all P < 0.0001, 0.55 < r< to 0.70) but a second test using only transects with observed burrows resulted in the loss of all correlations (all P > 0.05, r values ranged from 0.17 to 0.42). However, logistic regression analysis revealed the HSI model was able to predict burrow presence along transects (P = 0.0003). In Chapter 2, microhabitat variables and five GIS landscape variables were reduced into seven correlated principal components (PCs). According to a generalized linear (logit) model three PCs were significantly associated to active and abandoned borrows. Active burrows were positively associated to: 1) sandhill habitats, longleaf pine canopy, Lakeland soils, high elevations, xeric oak midstory, and wiregrass (Aristida beyrichiana) presence (overall P = 0.003; active P = 0.008); and 2) grassland habitats, little to no canopy, and increased herbaceous ground cover (overall P = 0.0042; active P = 0.0052). Active burrows were negatively associated to mesic flatwoods, Scranton soils, mixed pine canopy, high basal areas, and increased percent tree canopy (overall P = 0.003; Active P = 0.008). Abandoned burrows were positively associated to xeric hammocks, xeric hardwood canopy, mesic hardwoods midstory, increased canopy cover, increased litter ground cover, and increased mean years between burns (overall P = 0.0448; abandoned P = 0.0137). The relationship between fire suppression and burrow abandonment is widely accepted but poorly documented, and the poor resolution of this fire layer accentuates the importance of this detected relationship.

The goal of this study was to isolate biological, natural, and silvicultural factors that encourage the production of epicormic branches on bottomland red oak saw-timber trees and to use this information to help landowners and forest managers reduce epicormic branches in stands dominated by bottomland red oaks. Quercus nigra, Q. pagoda, Q. phellos, and Q. texana, the most common commercial bottomland red oaks in Louisiana, were evaluated in this study. Both qualitative and quantitative variables were assessed in this study. The following attributes were collected from each sample tree and primary competitor: site class, basal area, crown class DBH, presence or absence of epicormic branches, soil series, flooding regime, total tree height, height to base of live crown, live crown ratio, localized disturbance, and distance to nearest competitor. A total of 768 trees were evaluated, of which 384 trees displayed epicormic branching and 384 were without epicormic branches. Sample trees of all four species were equally distributed across four crown classes (dominant, co-dominant, intermediate, and suppressed). Equal numbers of all four oak species were collected to maintain homogeneity within the dataset. Logistic and Poisson regressions were used to analyze the data. An á level of 0.1 was considered effective for significance in this exploratory research. Logistic regression analysis yielded three variables significant in relation to the probability of epicormic branch occurrence. Variables significantly affecting the probability of epicormic branch production were total height of the sample tree, distance from the sample tree to the primary competitor, and crown class of the nearest primary competitor. The Poisson regression analysis was used to evaluate the number of epicormic branches a tree might produce. In this analysis dbh of the sample tree, crown class of the primary competitor, disturbance, flooding regime, and live crown ratio of sample trees were significant in relation to the number of epicormic branches produced. Tree, site, and environmental characteristics isolated as being important to epicormic branch production produced a means for evaluating the potential development of epicormic branches. These factors in concert provide the forester or land manager with a simple means of enhancing bottomland red oak value. The driving mechanism for sudden appearance of epicormic branches seems to be related to reduced tree vigor as affected by competition (or relative vigor based on relative height to competitors) and site stress factors. Taller trees with less competition from similar sized trees have a reduced probability of epicormic branches. Or stated in another way, trees with close competitors or nearly equal height are more likely to produce epicormic branches. Dominant trees have a reduced likelihood of developing epicormic branches if other stress factors are not at play. Intermediate and suppressed crown class trees should be removed during early thinnings of red oaks stands to avoid or reduce epicormic branch production. In concert, factors reducing competition and decreasing tree vigor tend to reduce the probability of epicormic branch production on bottomland red oaks.

With an estimated population loss of at least 5% annually and a 100-year history of decline, Rusty Blackbirds (Euphagus carolinus) are one of the fastest declining bird species in North America. Determining cause of decline is important, both for conserving the species and for identifying threats to the wooded wetland ecosystems they use on their boreal breeding-grounds and their wintering-grounds in the southeastern United States. One hypothesis is that loss of wintering ground habitat, possibly in conjunction with competition or disease, is causing Rusty Blackbird decline. To determine contribution of wintering ground conditions, it is important to understand the behaviors and habitat requirements that make these birds prone to decline. My research objectives were to develop survey strategies for detecting and quantifying Rusty Blackbird presence, to examine inter- and intraspecific associations for potential competition, and to determine habitat requirements at spatial scales appropriate to foraging movements. The present study uses data from 550 survey occasions and 163 independently collected birder observations to examine survey methods and seasonal trends over two winters. Occupancy modeling was used to investigate flocking behavior and habitat associations (at 25 m and 100 m scales) at 74 unique sites (naïve occupancy = 0.82, average occupancy by survey round = 0.51). Results indicate that Rusty Blackbirds may be less dependent on forested habitat than previously thought, but show strong a strong relationship to availability of wet ground. Range-wide alterations in hydrological processes, due to drainage or flood control, could lead to decreased quality or availability of shallow-water habitat and aquatic food resources. Rusty Blackbirds frequently flock with other blackbird species, and show similarities in use of open habitats. Competition cannot be ruled out and could worsen with use of degraded habitat. Overall results suggest that wintering behavior and habitat changes are likely contributors to long-term and continuing Rusty Blackbird decline.

Artificial oyster reefs seek to restore reef ecosystem services, such as water filtration, shoreline protection, and habitat for nekton. This study established three objectives to address the dispersed nature of artificial reef information in the Gulf of Mexico (GoM) and lack of post-construction monitoring assessments. First, to document the extent of activities in the GoM, we developed a database of all inshore artificial oyster reefs created for restoration purposes. Of the 422 reefs in the resultant database, a third or less provided records of entities involved (27%), restoration goals (24%), area (20%), monitoring efforts (15%), relief (9%), and costs (8%). Material (89%) and age (66%) records showed reefs were primarily built with rock (48.6%, limestone or concrete) or shell (12.8%) materials; a quarter of projects (26%) occured after Hurricane Katrina (2005). Second, in a field study we examined the success of artificial subtidal reefs using the presence of (a) living oysters and (b) hard substrate as indicators of success. This field study sampled historic (N=7) and artificial shell (N=5) and rock (N=8) reefs in 8 bays along the northern GoM. Rock artificial reefs were more successful on average than shell, providing significantly higher mean adult oyster density and hard substrate volume. In addition to material effects, design (i.e., relief) and placement specific environmental variations (i.e., hydrodynamics) may have affected success. Lastly, to assess artificial reef use by nekton communities, we sampled nekton assemblages with 3 gear types (gillnet, castnet, and shrimp trawl), during 4 trips in summer 2011. Overall, abundance, richness and diversity were similar between historic reefs and both artificial reef materials (shell, rock). It is probable that biophysical variations may have affected nekton use, more than reef structure. Of the reefs sampled, only 65% of the artificial reefs were fully successful in providing reefs with hard substrate and living oysters, while all reefs provided similar nekton support. This project highlights the need to better track restoration projects in order to inform future activities. Identifying aspects of design and/or location that influence reef success is critical for improving restoration activities.

Insulin resistance in type 2 diabetes is associated with impaired glucose and protein metabolism in skeletal muscle. The impaired insulin signaling in skeletal muscle affects muscle mass by tilting the balance between skeletal muscle protein synthesis and degradation toward degradation, a process that is primarily regulated by the ubiquitin-proteasome system. Studies have shown that an extensively characterized ethanol extract of Artemisia dracunculus L (Russian Tarragon), termed PMI 5011, enhances insulin signaling in human primary skeletal muscle cells and in a rodent model of insulin resistance. The aim of this project is to determine if the effect of PMI 5011 on insulin signaling extends to regulation of ubiquitin-proteasome activity in skeletal muscle. To evaluate the effect of PMI 5011 on the ubiquitin-proteasome system, we used two in vitro models of insulin resistance in C2C12 myotubes and the KKAy mouse model of insulin resistance in vivo. Our studies show that PMI 5011 enhances the inhibitory effect of insulin on proteasome activity and ubiquitylation in skeletal muscle in vitro and in vivo. In addition, PMI 5011 inhibits non-proteasomal protein degradation in vivo, indicating that PMI 5011 is a potent inhibitor of skeletal muscle protein degradation. PMI 5011 also regulates the expression of Atrogin-1 and MuRF-1, muscle-specific ubiquitin ligases that are required for ubiquitin-dependent protein degradation in skeletal muscle. Both Atrogin-1 and MuRF-1 gene and protein expression is elevated with impaired insulin signaling and our studies show that PMI 5011 reduces the expression of these ligases while enhancing Akt phosphorylation. In summary, these studies demonstrate that PMI 5011 regulates the ubiquitin-proteasome in insulin resistant states in vitro and in vivo. PMI 5011 may therefore be a therapeutic target for enhancing insulin sensitivity leading to conservation of muscle mass in type 2 diabetes.

Crayfish harvested from the Atchafalaya River Basin (ARB) represent the majority of Louisiana wild crayfish landings. However, excluding water level influences, it is difficult to elucidate inter-annual harvest differences and intra-annual population variability among habitats. This research investigated ecological influences on population characteristics of red swamp crayfish Procambarus clarkii in the southeastern ARB as well as physiological biomarkers of hypoxic stress in P. clarkii. Biotic and abiotic effects on P. clarkii populations were examined throughout the 2008 and 2009 commercial crayfish seasons. P. clarkii catch per unit effort (CPUE) at sampling locations increased nearly 600% between sample years despite similar hydrologic and physicochemical conditions. The passage of Hurricane Gustav between sample years caused near anoxic conditions for several weeks throughout the lower ARB. Increased allochthonous inputs and reduced fish predation associated with Gustav likely contributed to the increased P. clarkii CPUE observed during 2009. During 2008, P. clarkii CPUE was highest at sample locations characterized by high dissolved oxygen (DO) concentrations and lowest at locations with relatively low DO levels. In addition, chronically hypoxic sampling locations yielded lower mean CPUE and carapace length during 2008. An increase in P. clarkii mean CPUE and a concomitant decrease in mean carapace length during the 2009 crayfish season indicated density-dependent growth. While abiotic factors undoubtedly influenced crayfish population characteristics, relative density appeared to have the largest effect on P. clarkii carapace length and may have depressed any physicochemical influences. Lactate, glucose, and protein concentrations in P. clarkii hemolymph were examined in individuals from chronically hypoxic ARB habitats and laboratory simulated hypoxia experiments. P. clarkii from normoxic and hypoxic natural habitats did not display significantly different hemolymph lactate or glucose concentrations, however, mean hemolymph protein concentration was significantly lower in crayfish from hypoxic areas. P. clarkii exposed to severe hypoxia in laboratory experiments had significantly higher hemolymph lactate and glucose concentrations, whereas large differences in protein concentrations were not observed. A hand-held lactate meter and refractometer proved to be reliable methods for determination of P. clarkii hemolymph lactate and protein concentrations, respectively.

Wetland birds are likely to be influenced by habitat at multiple spatial scales, yet few studies have investigated bird responses at both broad and fine scales. Northern Gulf Coast marshes are dynamic ecosystems, and they provide an ideal place to examine habitat across spatial and temporal scales. My research focused on the secretive marsh bird guild (i.e. bitterns, rails, gallinules, grebes) with an emphasis on the king rail (Rallus elegans), a species of high conservation concern. My objectives were to investigate the wetland bird-environment relationship across scales, and to model annual changes in bird distribution. Study sites were in the fresh and intermediate (oligohaline) marshes of the Chenier Plain coastal region of southwest Louisiana and southeast Texas. I captured king rails for a two year radio telemetry study, and conducted point count surveys of marsh birds from March to mid-June of 2009-2011 using call-back methods to elicit responses. I visited each point six times per year, and >100 points were surveyed each year (n=304). Localized, field-based measures (e.g. water depth), management, and broad marsh types were related to bird abundance, and species distribution models were developed for four species based on Landsat satellite imagery. Home ranges of king rails varied from 0.8-32.8 ha (n=22), rails selected for open water, and smaller home ranges were associated with greater open water within the home range (20-30%). Point counts showed fine-scale habitat models, usually incorporating water depth, were improved with the addition of broad-scale marsh type and management, classified as permanently impounded, drawdown, or unmanaged. For 12 of 13 species, a multi-scale model was better than any single spatial scale. Species distribution models showed satellite-based measures of habitat corresponded well to marsh birds as they explained 37-79% of the variation in abundance. Temporary water was the most important variable, and species' models were distinct for fresh and intermediate marshes. The spatial distribution of birds varied greatly among years, especially with migratory birds in the highly variable fresh marsh. Overall, marsh birds responded to the environment at a variety of spatial scales, and satellite-based distribution models showed broad-scale patterns and dynamic distributions among years.

One major drawback of biomass fuel is its bulky nature and the resulting high cost of transporting the fuel to the facility where the energy is being produced. Hence, supply chain of biomass residues plays a crucial role in determining the financial viability of bioenergy production. Transporting biomass for energy purposes more than 50 miles (80 km) is not considered economically feasible in most conditions. In the wood energy scenario, the maximum distance is more often restricted to distances of less than 200 km between production and consumption (via road). A study was done to determine logging residues and agricultural residues production for the 64 parishes in Louisiana and to compare the three different modes of transportation (freight) for wood biomass, namely rail, road and water. The average annual production for logging residues in the state from 2000 to 2010 was estimated around 3,073,978 bone dry tons (BDT) and for agricultural crop residue it was approximately 6,773,985 BDT annually (2005- 2011). The greatest production of logging residues was in the western and northern parishes of Louisiana, away from the population centers. The road network was the most extensive means of transportation. For long distances (greater than about 150 km), the Mississippi/Red River complexes could provide a very cheap source of transportation, followed by rail, but they had their own set of logistical problems. The river or rail networks were limited for the major logging residues producers (such as Winn, Vernon, Bienville, Union, etc.) and utilizing parishes. For agricultural residues, north-eastern and central parishes like Morehouse, Madison, Franklin, East Carroll and Pointe Coupee were the major producers. Soybean, rice, corn and sugarcane constituted the majority of the agricultural residue production. All the major agricultural parishes were in close proximity to ports in the state, which opened them to the waterway system.

Mottled ducks (Anas fulvigula) are the most abundant breeding waterfowl in the coastal marshes of Louisiana and Texas. Mottled ducks are non-migratory and heavily dependent on coastal marsh habitats; they must satisfy all of their annual resource needs from within the Gulf Coast region. Coastal marsh habitats are being rapidly lost or degraded in Louisiana and Texas. The hydrology of many coastal marsh habitats has been altered by anthropogenic activity and natural factors. Parameters related to Mottled Duck habitat use and movements in this altered environment are poorly understood, and managers need information on vital rates of Mottled Ducks in coastal Louisiana and Texas. Information on use of habitats, breeding pair densities, and movements of female Mottled Ducks could benefit managers charged with conservation of Mottled Ducks and coastal marsh habitats and be used to guide resource allocation for restoration and conservation in this region. Additionally, information on breeding propensity would satisfy a need to establish vital rates used for population modeling. I employed radio-telemetry techniques to evaluate use of habitats and movements by female Mottled Ducks in the Gulf Coast region. I used a transect survey as an index to pair densities in different habitats, and evaluated examination of postovulatory follicles as a method to assess breeding propensity in Mottled Ducks. Mottled Ducks used fresh and intermediate marsh heavily and pair densities were greatest in fresh marsh habitats. Mottled ducks had low movement distances and moved inland away from storm surge caused by hurricanes. Macroscopic examination of postovulatory follicles was not appropriate for evaluation of breeding propensity in Mottled Ducks. Conservation of natural coastal marsh habitats in Louisiana and Texas will benefit Mottled Ducks in the Western Gulf Coast region.