The Atchafalaya River Basin (ARB) experiences overbank inundations as springtime temperatures warm that create conditions favorable for bacterial respiration, which results in hypoxic conditions (dissolved oxygen [DO] ≤ 2.0 mg/L). Previous ARB research has shown that pelagic larval fish populations are impacted by hypoxic conditions, and that larvae may use macrophyte beds (e.g., hydrilla Hydrilla verticillata) as DO refugia. I examined the relationship between physicochemistry and the distribution and abundance or larval fishes associated with ARB macrophyte beds during 2001-2002. Larval fishes were collected with light traps at two normoxic and hypoxic sites, and at each site, surface and subsurface traps were placed in open channels, hydrilla beds, and the interface between the channel and macrophyte beds (border). Of the 1,718 larval fishes representing 10 families that were collected, centrarchids Lepomis spp. (45.5%) and catostomids Ictiobus spp. (25.7%) dominated the 2001 assemblage, whereas percids Etheostoma spp. (29.1%) and centrarchids (17.8%) were most abundant in 2002. River stages between years were different from each other (P < 0.001), and from the 42-year stage average (P < 0.001). Between-year differences in flood pulse timing and duration resulted in higher pH, temperature, and DO levels, and 2.5 times more larval fishes in 2001. Overall, larval fish abundances under hypoxic conditions were severely reduced during both years. Under normoxic conditions, larval fishes were collected from all habitats, but were typically in higher abundance in nearshore areas regardless of cover conditions (hydrilla vs. no cover). Larvae that could withstand hypoxic conditions (centrarchids, clupeids, cyprinids, and percids) were typically found in nearshore areas associated with hydrilla beds. Because of the increased abundance of predatory invertebrates in these areas, the use of hydrilla beds by fish larvae as oxygen refugia may provide optimal physiochemical conditions at an increased predation risk. Man-made alterations in the ARB have changed circulation patterns on the inundated floodplain, which contribute to seasonally widespread hypoxic conditions and reductions in larval fish abundance. Thus, any management plan that increases the historic connection between the mainstem Atchafalaya River and the floodplain, and improves floodplain circulation would benefit larval fish production in the ARB.

Eucommia ulmoides Oliver (Eucommiaceae) contains many secondary metabolites, including the lignan pinoresinol di-O-β] glucoside (PG) and the iridoid glycoside aucubin (AU), which have been shown to have anti-hypertensive, antioxidant, and hepatoprotective biological properties. The main objective of this research was to create a new agricultural crop in Louisiana for maintaining healthy blood pressure levels. This was done by: 1) determining the seasonal changes in the concentrations of PG and AU in four-year-old E. ulmoides trees in cultivation in Baton Rouge, Louisiana using Thin Layer Chromatography and High Pressure Liquid Chromatography (HPLC) and 2) determining production of secondary metabolites of E. ulmoides leaf tissue within callus culture using HPLC. While AU was produced within the cortex and leaves of cultivated trees, PG was not detected. AU was produced year round in both cortex and leaves, except for December and February when leaf abscission occurs. AU was measured in all of the monthly cortex samples, with the April 2001 sample yielding the highest concentration (1.42 μg/g). AU concentrations in June, August, and April 2002 leaf samples were not statistically different (p<0.05). Four levels of NAA (0, 3, 6, 9 mg/l) and BA (0, 1, 2, 4 mg/l) were used to induce callus cells from E. ulmoides leaves. AU was not detected by HPLC, but PG was found to be present in 13 of the 16 treatments. A ratio of 3 mg/l NAA to 4 mg/l BA produced the highest PG concentration. The information gained from this data can be used to determine an efficient harvesting scheme for the extraction of secondary metabolites produced by Eucommia ulmoides.

Development of a cryopreserved sperm repository could greatly benefit the study and recovery of endangered species. Currently, a national repository for endangered aquatic species does not exist. This dissertation addressed the development of methods for the creation of a model germplasm repository, which included methods to reduce bacterial contamination within sperm samples, verify sample identification, store sperm (refrigerated or cryopreserved), evaluate sperm quality before and after thawing, and maintain sample and broodstock information. Although these methods were developed for sturgeon, they could be adapted for any aquatic species. Accurate species identification of sperm samples is essential for an archival repository. A polymerase chain reaction and restriction digest method was developed to identify three sturgeon species, and separate the remaining species into distinct groups. Bacterial contamination of sperm samples can lead to sample deterioration and transmission of pathogens. Twenty-seven species of bacteria from 15 genera were isolated from sperm samples of sturgeon in this study. Addition of antibiotics did not lengthen refrigerated storage time. Cryopreservation procedures developed for sturgeon sperm did not reduce bacterial numbers in thawed samples compared to pre-freeze numbers. Seminal plasma osmolality (100 mOsmol/kg) and sperm activation data (reduction in potassium ion concentration) were used to develop extenders. Hanks balanced salt solution or modified Hanks balanced salt solution (mHBSS) at 100 mOsmol/kg allowed refrigerated storage of sperm for as long as 21 d. Sperm were cryopreserved using mHBSS (100 mOsmol/kg), methanol (5% or 10%), a cooling rate of 22-24 oC/min, and 0.5-ml straws. A dual-staining flow cytometry technique was used to determine gamete quality in sperm samples before and after thawing. The procedure was validated by evaluating membrane integrity in mixed populations of untreated cells and heat-treated membrane damaged cells. When used with thawed samples, whenever membrane integrity was correlated (r2 > 0.8068) to percent fertilization and hatch, motility was also correlated (r2 > 0.7650) to percent fertilization and hatch. A computer database was developed using MicrosoftÒ Access to maintain inventory and quality control of sample information. The database is currently being used at the Warm Springs Fish Technology Center of the United States Fish and Wildlife Service.

Since the mid 1990s Ghana's forestry sector has been going through reforms geared towards achieving the ITTO Year 2000 Objective for sustainable forest management and forest product trade. The reforms were partly introduced through legal approaches and also through activities under a long-term Forestry Sector Development Master Plan. The legal approaches mainly dealt with strengthening of sector institutions to effectively carry out forest concession administration and management, stumpage fee increases and more punitive actions against forest offences. Reforms with more direct impact on forest product export trade came through the implementation of the Forestry Sector Development Master Plan - reduction in annual allowable cut (AAC), introduction of air-dry levy, and promotion of value-addition and lesser-used species (LUS). These actions have infuriated the forest product industry blaming the government for a collapsing industry as a result of the interventions. This study evaluated the impacts of the interventions believed to be directly affecting the forest product export trade and perceptions of marketing implications. The study concluded that: - 1. The drop in raw material level has influenced increasing export of kiln-dried lumber and processed lumber molding. The air-dry levy is observed to be working well as a disincentive to export of commodity products by reducing export of air-dried lumber and increasing kiln-dried lumber and sliced veneer. 2. The air-dry levy showed a significant effect with an increase in percent of LUS (used as a measure of species diversification) exported in the post-intervention time period. 3. There is the need to improve machinery upgrade to include CNC technologies, relationship with buyers, strengthening of wood inspection authority, flexibility in terms of trade, Internet capabilities, and financial support to the industry.

With continued marsh break-up and loss in Louisiana, small interior ponds are created, increasing areas of shallow water habitats. These shallow water habitats are potential sites for submerged aquatic vegetation (SAV) establishment. It is important to characterize nekton community composition, density, biomass, and growth within brackish marsh pond microhabitats because SAV is often cited as essential fish habitat (EFH). Three microhabitat types were investigated: (1) inner-pond SAV (> 1 m from edge); (2) near marsh-edge SAV (< 1 m from edge) and (3) nonvegetated bottom. We tested the null hypotheses that nekton community composition, density, and biomass were not related to microhabitat type and characteristics. Ninety-six quantitative samples were taken with a 1-m² throw trap between September 2001 and July 2002. The two vegetated microhabitats were characterized by monotypic stands of widgeon grass Ruppia maritima and contained similar biomass. Nekton community composition, density, and biomass did not differ between vegetated microhabitats, but differed significantly from the nonvegetated microhabitat (p < 0.0001). Therefore, SAV appears to be a dominant factor influencing nekton distribution within ponds. Submerged aquatic vegetation beds may also provide nekton with better growth environments by providing better quality or quantities of food for nekton than nonvegetated habitats. We also tested the null hypothesis that nekton growth was similar between vegetated and nonvegetated habitat types to determine if SAV provided a greater food resource than nonvegetated bottom. An in situ field experiment was conducted that compared growth rates of Atlantic croaker Micropogonias undulatus between vegetated and nonvegetated habitats to investigate the role of SAV in supporting nekton growth. We detected no statistically significant difference in nekton growth between vegetated and nonvegetated habitats (p = 0.125).

Understanding habitat needs of animal populations is critical for their effective management. In recent years, technological advances have increased the range of methods available to examine habitat selection patterns. However, available habitat data are often either limited to small geographic areas or are of coarse resolution, resulting in a gap in data to model habitat selection at landscape scales. I explored a method of processing Landsat data, the at-satellite reflectance tasseled cap, to address this data gap using black bears in south central Louisiana as a case study. As I showed, this case was particularly instructive because these bears occupy two very different habitat matrices. I examined the information content of resource measures derived from tasseled caps and determined that they contain substantially more information than is represented in coarse habitat maps such as available from the USGS GAP program. Additionally, this process could be applied over large areas and time frames, during different times of the year, and across sensors to produce consistent results that avoid the need to categorize land cover/habitats. I used logistic regression and the information theoretic approach to examine: the spatial scale at which habitat measures were derived, model complexity, and the relative value of groups of derived habitat measures. I grouped derived habitat measures to examine the information content in: images captured in two seasons, measures based on mean and standard deviation filters, and combinations of tasseled cap functions. My work suggests that researchers should consider multiple summary statistics derived over a range of scales, use multi-temporal data, and use all three tasseled cap functions to derive habitat measures. I calculated resource selection functions (RSF) for black bears in south central Louisiana and examined model calibration and discrimination. Mahalanobis distance has been proposed as an alternative to RSF because it does not require delineation of available resources, although results from the two approaches have not been compared. In this study, habitat quality predictions from RFS models more accurately depicted bear habitat preference than those of Mahalanobis. I propose an alternative use of Mahalanobis distance to direct model extrapolation beyond the boundaries of modeled populations.

Food abundance might limit survival or recruitment of wintering waterfowl. Nutritional requirements of wintering waterfowl have been estimated, but there are insufficient data on the abundance of seeds and submerged aquatic vegetation (SAV) to determine if enough habitat exists to support target populations of waterfowl throughout winter. I estimated waterfowl food abundance at 14 coastal freshwater marsh sites in Texas and Louisiana from August 2001 to March 2003, and tested the hypothesis that wintering waterfowl reduce food abundance. I analyzed 210 and 360 seed and SAV samples, respectively, taken during September 2001, February 2002, September 2002, and February 2003 to estimate seed and SAV biomass and determine if biomass declined during the winter. At one site, SAV biomass was estimated from 108 samples taken at six-week intervals (August-March) to provide another means of determining if food abundance declined throughout winter. Also at that site, 108 samples were taken from waterfowl exclosures in August and January of each year to provide another means of determining if wintering waterfowl reduce food abundance. Seed and SAV biomass estimates were not significantly different among time periods; biomass estimates of 14 genera of seeds and 8 genera of SAV collected averaged 244.2 ± 23.8 kg/ha (mean ± SE) and 262.3 ± 95.0 kg/ha, respectively. No significant differences in SAV biomass were detected among time periods at the six-week site or among time, treatment, and treatment by time interactions at the exclosure site. Mean food biomass estimates were well above the 50 kg/ha threshold estimate assumed to be the point of diminishing returns for feeding waterfowl. These findings also indicate that waterfowl did not significantly lower food resources in my study area over the two years of my study.

Chemical coupling plays an important role in improving interfacial bonding strength in wood-polymer composites. In this study, the effects of coupling agent type and structure, graft polymerization of coupling agents, interfacial wettability, coupling treatment and process, coupling agent distribution, and coupling agent performance on chemical coupling were investigated. Coupling mechanisms were established based on maleated polyethylene copolymers. For maleated wood veneer, the relationship among graft rate, concentration, and retention of coupling agent followed three-dimensional parabloid models. Wettability of maleated wood surface was related to acid number, amount of free or ungrafted maleic anhydride groups, and coupling agent concentration. Dynamic contact angle of water droplets on maleated wood followed the natural decay process, whereas the spreading process of droplets fitted the Boltzmann sigmoid model. Compared with untreated composites, maleated composites had significant shifts in most TGA, DSC, and DMA spectra because of chemical coupling at the interface. For melt-blending process, the best interfacial bonding strength was achieved at short compounding time (e.g., 10 min), appropriate mixing temperature (e.g., 180oC), and moderate rotation speed (e.g., 90 rpm). With FTIR, ESCA, and SEM analyses, the evidence of chemical bridges at the interface was proved. The interfacial morphology was illustrated with the pinwheel models. For wood-plastic laminates, interfacial adhesion followed the monolayer models, while brush, switch, and amorphous structures applied to melt-blended composites. Therefore, the interface was strengthened with covalent bonding (such as esterification and carbon-carbon bonding), strong secondary bonding (e.g., hydrogen bonding), macromolecular chain entanglement, and mechanical interblocking. Coupling agent performance for maleated copolymers was mainly related to their acid number, molecular weight, backbone structure, and concentration. Coupling agents with large molecular weight, moderate acid number, and concentration were preferred to have better performance at the interface. Based on the experimental results, 226D, 100D, and C16 were the best coupling agents among seven maleated copolymers used in this study. Compared with untreated composites, maleated composites increased interfacial bonding strength by 140% and flexural modulus by 29% at the concentration level of 3%.

To address public concern over potential ecological effects on commercially and ecologically important species following use of dispersants during oil spill response efforts, toxicity data was generated for three estuarine species indigenous to the Gulf of Mexico including juvenile Gulf killifish Fundulus grandis, white shrimp Litopenaeus setiferus, and Eastern oyster Crassostrea virginica. The acute toxicity of the dispersant Exxon Corexit 9500, South Louisiana crude oil (SLC), Alaskan north slope crude oil (ANSC) and dispersed oils (SLC+9500 and ANSC+9500) to the species was determined for both nominal concentrations (NC) and hydrocarbon concentrations (HC). Two 24-h field toxicity trials were conducted with the same species in a Louisiana coastal marsh, using ANSC and ANSC+9500, dosed at a NC of 30 ppm. White shrimp were more sensitive to dispersant, crude oils, and dispersed oils than killifish and oysters. The 96-h NC LC50 for crude oil and dispersed oil ranged from 370 to 4,500 ppm for killifish (HC 7.6 to 18.7 ppm) and 60 to 180 ppm for shrimp (HC 5 to 7.5 ppm). Mortality in oysters was not positively correlated with increasing levels of crude oils, or dispersed oils. Dispersed oils were more toxic than crude oils based on nominal concentrations, but no difference in toxicity of crude oils and dispersed oils was observed based on HC concentrations. No synergistic toxicity action was found between SLC or ANSC and dispersant Corexit 9500 based on HC concentrations. Survival was relatively high for all three species during the two 24-h field trials, generally exceeding 83% in crude oil and dispersed oil enclosures. Mortality of white shrimp was slightly higher than observed in killifish and oysters. The HC concentration in ANSC+9500 and ANSC enclosures ranged from 14 to 24 ppm and 10 to 11 ppm, respectively, at 0 h and declined to near 0 ppm in 3 hours. The rapid decrease was attributed to dilution from vertical mixing and tidal action. Both laboratory finding and field studies indicate that short-term exposure to nominal concentrations of ANSC or ANSC+9500 of 30 ppm or less are not likely to have an acute toxic effect on these species.

Chromated copper arsenate (CCA) treated wood is an economical, durable and aesthetically pleasing residential material used for many exterior application such as decks, fences, playground equipment, utility poles, and others. It has been most widely used in North America since the 1970s. A large volume of CCA-treated wood is currently coming out of service. Traditional landfilling or incineration is environmentally unacceptable. Recycling CCA-treated wood into composite products is one alternative to ease the disposal problem. It also has the potential to relieve harvesting pressure from the nation's forestlands. After recycling, the remaining CCA content in the wood can still have preserving capability against decay. In this study, the effects of different ratios of recycled CCA-treated wood and untreated virgin wood on flakeboard properties were compared. The mechanical, physical, decay resistance, elemental concentrations, and leaching characteristics of flakeboards manufactured from five different ratios of recycled CCA-treated wood and untreated virgin southern pine wood were investigated. The ratios were 100:0, 75:25, 50:50, 25:75, and 0:100. The CCA retention levels of out-of-service CCA-treated posts (experimental raw material) as well as the flakeboard fabricated from the different ratios of recycled CCA-treated wood and untreated virgin wood were also tested. The median ratio with 50% of CCA-treated wood and un-treated wood was found to be the optimum combination. In this case, residual CCA level was sufficient enough to prevent substantial weight losses for the decay tests but low enough so that panel mechanical and physical properties were not substantially adversely affected.