The Mississippi and Atchafalaya rivers are the major sources of freshwater and nutrients to the Gulf of Mexico. Increased nutrient loads from these rivers exacerbate eutrophication in coastal receiving waters and contribute to the large area of hypoxia that develops seasonally in the Gulf. Levees along the Mississippi River have reduced contact between the river and the historic floodplain; this limits the ability of floodplain wetlands to naturally mitigate excess nutrients. However, the Atchafalaya River diverges from the Mississippi 217 km from the Gulf and enters a large river floodplain with a widely spaced levee system. This enhances the ability of the Atchafalaya River Basin to remove and sequester nutrients, potentially reducing downstream eutrophication. Overbank flow spreads river-water and sediment across the floodplain. Over time, sedimentation has filled in many of the open water areas on the floodplain, such that lakes are transitioning to baldcypress swamps and bottomland hardwood forests. These habitats differ in their available nutrient reservoirs and the rates at which they transform and store nutrients. This dissertation investigated the major retention and removal mechanisms for carbon, nitrogen, and phosphorus within bottomland hardwood forests, baldcypress swamps, and lakes of the Atchafalaya River Basin. These reservoirs include denitrification, sedimentation, and assimilation by aboveground biomass. Results estimate that nutrient retention and removal within bottomland hardwood forests ranges from 1,177,6051,561,805 t C yr-1, 46,04947,603 t N yr-1 and 20,04020,175 t P yr-1. Within baldcypress swamps, rates range from 493,953600,180 t C yr-1, 21,82122,364t N yr-1 and 2,1682,202 t P yr-1. Rates in the lakes were 57,490 t C yr-1, 5,1405,390 t N yr-1 and 2,550 t P yr-1. Total retention and removal for the entire basin is on the order of 1,177,6051,561,805 t C yr-1, 46,04947,603 t N yr-1, and 20,04020,175 t P yr-1. Rates varied by habitat, highlighting the need to consider habitat change when developing management strategies to improve water quality. Data from this dissertation can be used to parameterize nutrient models for the Atchafalaya River Basin, as well as for river diversions and floodplains with similar habitat types.

Zooplankters are important members of freshwater communities, facilitating the transfer of energy from primary production to higher trophic levels. Lentic floodplain systems are important in providing zooplankters with adequate habitat for growth and reproduction. Recently, The Nature Conservancy has been interested in cataloguing the aquatic taxa that inhabit the Ouachita River and floodplain in northern Louisiana, concurrent with an attempt to reestablish a river-floodplain connection with the river and eastern floodplain (the Mollicy Farms Unit, part of the Upper Ouachita National Wildlife Refuge). Sampling was conducted at seven sites along the Ouachita River and western floodplain monthly for one year to investigate zooplankton density and composition in relation to environmental variables and hydrology. Principal component analysis was used to illustrate relationships among zooplankton groups with environmental variables and sampling sites, and cladoceran taxa were found to be correlated to specific environmental variables by multivariate analysis of variance. Results indicated that highest densities were exhibited by rotifers, followed by copepods and cladocerans. Abundances of the zooplankton groups were correlated primarily with specific conductance, PO4, temperature, chlorophyll a, Secchi depth, and dissolved oxygen. Additionally, average densities of zooplankton groups were greater at floodplain sites than at sites near or within the river mainstem. During the low water phase, copepods and certain cladoceran taxa were found in greater densities than during the high water phase, indicating a potential concentration effect. These findings will contribute to our understanding of the interactions between environmental parameters and zooplankters within the Ouachita River and floodplain, as well as an overall understanding of zooplankton dynamics in river-floodplain systems.

The influence of sodium hydroxide treatment on the structure of cotton fibers was studied. Compared to raw cotton fibers, the entire bundles of mercerized fibers were converted into a swollen and roughened state. Fourier transform infrared spectrometry (FTIR) indicated that intermolecular hydrogen bonding was enhanced by mercerization treatment. Wide-angle X ray diffraction (WXRD) results showed decreased fiber crystallinity after mercerization. The structure of cellulose II fibers was more thermally stable than cellulose I fibers. Mechanical properties of cotton fiber-reinforced polyethylene oxide (PEO) composites demonstrated that both raw and mercerized cotton fibers enhanced their tensile strength of the PEO matrix, but both made the composites more brittle due to poor fiber dispersion in the PEO matrix. Cotton nano crystals (CNCs) were fabricated from both raw and mercerized cotton fibers by sulfuric acid hydrolysis combined with a high-pressure homogenization technique. Stable aqueous suspensions from both raw and mercerized CNCs were formed. Transmission electron microscopy (TEM) suggested that there was no obvious change in crystal morphology from raw and mercerized cellulose. Dry mercerized crystals had a much larger bulk density than the dry raw crystals. FTIR and WXRD data showed a clear transition from cellulose I (raw) to II (mercerized) cellulose crystal structure. TGA curves showed that cellulose II CNCs had better thermal stability properties. The storage modulus of cellulose II CNC suspensions at all temperatures were obviously larger than those of cellulose I crystal suspensions at the same concentration level. Cellulose II CNC suspensions/gels were shown to be more thermally stable in response to temperature changes. Dilute cellulose II crystal suspensions formed an ordered liquid phase displaying chiral nematic orientation in the direction of the vector director at a much lower concentration level compared with cellulose I crystal suspension. Both cellulose I CNC /PEO and cellulose II CNC/PEO composites showed increased tensile strength and elongation at break compared with these of the pure PEO. However, composites with cellulose II crystals exhibited larger tensile strength, and elongation at break than those from composites with raw crystals due to the enhanced hydrogen bonding. Thus, cellulose II nano crystals provide better reinforcement materials for manufacturing advanced nano-composites.

Compared to other distribution functions, the Weibull distribution has been more widely used in describing diameter distributions because of its flexibility and relative simplicity. Parameters of the Weibull distribution are generally predicted either by the parameter prediction method or by the parameter recovery method. The coefficients of the regression equations for predicting Weibull parameters, moments, or percentiles are often estimated by use of different approaches such as ordinary least squares (OLS), seemingly unrelated regression (SUR) or cumulative distribution function regression (CDFR). However, there is no strong rationale for preferring one method over the other. We developed and evaluated different methods of predicting parameters of Weibull distribution to characterize diameter distribution using data from the Southwide Seed Source Study. The SUR and the CDFR approaches were applied to ten different parameter prediction and parameter recovery methods. A modified CDFR approach was developed by modifying the CDFR technique such that the CDF is computed using information from diameter classes instead of individual trees as in the CDFR approach. These methods were evaluated based on four goodness-of-fit statistics (Anderson-Darling, Kolmogorov-Smirnov, negative Log-Likelihood, and Error Index). The CDFR approach provided better results than the SUR approach for all methods. The Modified CDFR approach consistently provided better results than the SUR approach, and was superior to the CDFR approach in all evaluation statistics but the Anderson-Darling statistic.

Commercial pine (Pinus spp.) forests in the southeastern United States are key to providing fiber for global wood supply needs. Concern has arisen over possible effects of intensive forest management techniques, including row spacing and distribution of woody debris after logging, on plant and wildlife communities. Therefore, we quantified response of plant and small mammal communities in replanted loblolly pine (P. taeda) stands to mechanical site preparation including 2 levels of row spacing and 2 methods of distributing woody debris following harvest in north and southeastern Louisiana, USA. Sites (n=16) were prepared with a combination of row spacing between planting beds (4.3 m and 6.1 m) and distribution of logging debris (piled and scattered). We examined vegetation using various sampling methods, and used mark-recapture techniques to assess small mammal communities in each of 4 replicate stands for 4 years post-treatment. Site preparation involving wider row spacing generally did not affect vegetation structure and composition; or relative abundance and diversity of small mammals. Piling debris in specific locales throughout the stand reduced non-pine woody vegetation, but did not affect small mammal communities. However, the increased woody growth associated with scattering debris throughout the stand resulted in higher lactation-level carrying capacity estimates for white-tailed deer (Odocoileus virginianus); due to importance of semi-woody browse to deer in Louisiana. We suggest that row spacing may not be a significant factor when planning implementation of site preparation techniques relative to small mammals and deer browse production. We suspect further research examining later stages of succession and stand development may provide further insight into the tradeoffs between increased woody growth associated with scattering debris and the potential benefits that may result from reducing woody growth by piling debris into certain locales throughout the stand.

White-tailed deer are the most important game species in Louisiana, and throughout the southeastern United States. Likewise, the forest products industry represents the most important agricultural commodity in Louisiana, and industrial landowners frequently lease their properties to sportsmen specifically for white-tailed deer hunting. I conducted research assessing survival, space use, and habitat selection of white-tailed deer on a 3885 ha industrial forest owned by Plum Creek Timber Company. I captured 61 deer in Union Parish, Louisiana in 2009-2010, radio-marked 24 females and 23 males, and ear-tagged 7 females and 6 males. Season and sex interacted to affect home range and core area sizes. Males home range sizes varied seasonally and were 232 ha, 70 ha, and 129 ha for spring, summer, and fall respectively. Female home range sizes did not differ seasonally and were 104 ha, 90 ha, and 62 ha for spring, summer, and fall respectively. Forest openings were important to both sexes when establishing home ranges. Core area selection exhibited a season and sex interaction as both sexes shifted selection in the fall to 0-4 year old pine and 13-19 year old pine stands. Use of habitats within home ranges did not vary by sex, season, or an interaction between them. Males and females chose 5-12 year old pine stands consistently across all seasons. Survival differed by season, but not by sex. Survival rates for adult males in spring, summer, and fall were 0.95, 0.97, and 0.54 respectively. Survival rates for females were 0.95, 0.97, and 0.56 for spring, summer, and fall respectively. All fall mortality was hunting-related, whereas mortalities during spring and summer resulted from unknown causes. The extensive use of bait, primarily corn and rice bran, was thought to influence space use and survival, and further research is needed to determine the effects of baiting on susceptibility of harvest of different age classes and sexes.

Profitability of aquaculture enterprises worldwide has been affected by rising fish meal prices. Plant proteins are promising replacements for fish meal because of their lower cost and worldwide availability. The goal of this research was to provide nutritional information for the development of all-plant diets for Florida pompano by evaluating growth of fish fed soy-based, fish-meal-free diets and assessing the nutritional value of several plant protein sources. In the first experiment, juvenile Florida pompano were fed five, soy-based, fish-meal-free diets containing graded levels of soybean meal (SBM, or M) at 0, 20, 25, 30, or 35%, with the remaining protein provided by soy protein concentrate (SPC, or C) at 59, 46, 43, 39, or 36%, respectively. These diets were compared to a control diet that contained equal levels (30%) of SBM and SPC in combination with 10% menhaden fish meal. Weight gain of fish fed the control diet (ten times initial weight) was significantly higher than gain of fish fed M0/C59, M20/C46, or M35/C36 diets, but was not different (P > 0.05) from fish fed the M25/C43 or M30/C39 diets. No apparent trends in whole-body composition of pompano were found. Differences in growth appeared to be due to decreased feed intake related to palatability of some diets. Results indicated that fish-meal-free diets that contained 25-30% SBM and 39-43% SPC were as effective as a diet of similar composition containing 10% menhaden fish meal. The second experiment determined apparent digestibility coefficients (ADCs) for canola meal (CM), corn gluten meal (CGM), and distillers dried grains with solubles (DDGS). A reference diet and test diets containing 70% reference diet mixture and 30% test ingredient (CM, CGM, or DDGS) were used following typical methods for digestibility trials. Apparent crude protein digestibility of CGM (57.2%) was significantly higher than DDGS (20.6%) but similar to CM (38.6%). Apparent energy digestibility of DDGS (30.7%) was significantly lower than CGM (57.1%) but significantly higher than CM (21.3%). The reference diet formulation was hypothesized to be an additional factor that can influence the calculation of ADCs, in addition to the chemical and physical attributes of the test ingredient.

The goal of this project was to develop streamlined protocols that could be integrated into a standardized approach for vitrification of germplasm for all aquatic species. Vitrification (freezing by formation of glass rather than crystalline ice) is simple, fast, inexpensive, can be potentially used to preserve samples in the field, and offers new options for germplasm management especially appropriate for small fishes. Sperm were studied from freshwater fish (channel catfish Ictalurus punctatus), viviparous freshwater fish (green swordtail Xiphophorus hellerii), and marine fishes (spotted seatrout Cynoscion nebulosus, red snapper Lutjanus campechanus, red drum Sciaenops ocellatus, and southern flounder Paralichthys lethostigma). To reduce toxicity, combinations of cryoprotectants at reduced concentrations with incorporation of trehalose and polymers were used to enhance glass formation. For freezing, samples were suspended on 10-µL polystyrene loops and plunged into liquid nitrogen. Thawing was done at 24ºC using Hanks balanced salt solution at 300 mOsmol/kg for freshwater species, and seawater at 1,020 mOsmol/kg for marine species. Quality after vitrification was evaluated by sperm motility, membrane integrity and when possible fertility. Post-thaw motility of sperm in marine fishes was higher (as high as 70%) than in freshwater fishes (as high as 20%). The percentage of membrane-intact sperm for marine fishes was ~20% except for southern flounder (11%). For freshwater fishes, the percentage of membrane-intact sperm for swordtail was low (<12%) compared to channel catfish (~50%). Adaptations by marine fish to high osmotic pressures could explain the survival in the high cryoprotectant concentrations (40 60%) required for vitrification. This research yielded the first successful vitrification of sperm in these fishes and production of offspring from vitrified sperm in channel catfish, green swordtail, and southern flounder. Sperm vitrification offers an alternative approach to conventional cryopreservation for conservation of valuable genetic lineages, such as endangered species, model strains used in research, and improved farmed strains. Furthermore, sperm vitrification could be used to transport cryopreserved sperm from the field to the laboratory to expand genetic resources available for germplasm repositories. This technique could be utilized to reconstitute genetic lines, and as a new option for conservation biology in imperiled aquatic species.

Forest carbon sequestration is regarded as a viable and cost effective option for reducing global greenhouse gas emissions. Several research studies analyzed the effects of joint management of carbon and timber under different even-aged forest management scenarios, and concluded that carbon benefits can alter forest management schedules significantly. However, research specifically focused on the inclusion of carbon sequestration benefits into uneven-aged management has received little attention. This study determined the optimum joint management regime of timber and carbon in uneven-aged loblolly pine stands in Louisiana, and assessed management and financial effects resulting from the integration of carbon benefits into uneven-aged management. The USDA Forest Vegetation Simulator (FVS) Southern (SN) variant was used to generate both growth and carbon data of uneven-aged loblolly pine stands. The generalized Faustmann model for uneven-aged management was applied to calculate the land expectation value (LEV) at every level of residual basal area and cutting cycle. In order to analyze the effects of changes in interest rate, stumpage prices, and future land values, comparative static analyses were carried out at three different interest rates, stumpage prices and future land values. This study determined the residual BA of 60 ft2/acre and cutting cycle of 18 years as the optimum timber management regime of uneven-aged loblolly pine stands at the interest rate of 4% and 2010 stumpage prices in Louisiana. Changes in interest rates and stumpage prices altered the optimum management schedules significantly, but effects of changes in future land value were minimal. In the joint optimization of timber production and carbon sequestration, carbon benefits were found influential in both financial and management perspectives. At every level of interest rates, the joint management of timber and carbon increased the LEV, extended the cutting cycle, and shifted the residual stocking to higher level. The joint management of timber and carbon under uneven-aged management is profitable, and the carbon offset would provide an important additional income source to landowners in the southern USA.

Energy producers, developers, legislators, policy makers, and the public are searching for alternative energy sources to alleviate energy demands and dependency on fossil fuels. Of the renewable energy sources, biomass from forestry, crop, and animal residues offer a clean and sustainable solution to help mitigate climate issues and stabilize energy needs. However, most forests and farms in the U.S. are privately owned. Its important to understand forest landowners, agricultural producers, and poultry producers attitudes and perceptions towards management activities intended for producing bio-based products. Three surveys were conducted tailored for each group. We surveyed 3,500 small to medium forest landowners in Southwest Louisiana, 2,964 small to medium agricultural producers in the Delta region of Louisiana and Mississippi, and 846 poultry producers within the U.S. Results from all three surveys suggest respondents were positive about utilizing biomass for bioenergy. Results from all three surveys suggests a large portion neutral attitudes respondents have towards bio-based issues are due, in part, to low levels of familiarity on the subject. Also, the majority believed that viable technologies exist for converting biomass to bioenergy. However, most believed its a low-value product compared to traditional products. For forestry and agricultural respondents, just over half were willing to participate in management activities specifically geared for biomass production. These older respondents are more likely to agree that harvesting biomass will negatively impact wildlife habitat, air, water, and soil quality. Also, they had a higher propensity to agree that tax credits, subsidies, and incentive programs should not be provided for biomass establishment, selling, and utilization. In contrast, results suggest that larger landowners and producers are less likely to agree that harvesting biomass will negatively impact wildlife habitat, air, water, and soil quality. Also, they are more likely to agree tax credits, subsidies, and incentive programs should be provided for biomass establishment, selling, and utilization. For poultry producers, results indicate that the majority would participate in the sale of poultry litter biomass and biomass markets. Also, poultry producers appeared to have a higher level of familiarity towards biomass concepts and issues when compared to forest landowners and agricultural producers.