Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Wildlife and Fisheries Sciences" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Thesis (M. S.)--Texas A&M University, 2006. / "Major Subject: Wildlife and Fisheries Sciences" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

This study examined several aspects of canopy structure and their influence on growth of loblolly pine (Pinus taeda L.) plantations. Foliage distribution, crown hydraulic architecture, and the effect of chronological changes in canopy structure on stand development were explored as possible components of a future process-based model intended for management purposes. A model based on the Johnsons SB distribution was developed to predict leaf area distribution of loblolly pine trees. This is a preliminary step for building a submodel capable of simulating chronological changes in canopy structure and stand growth. The model accurately predicted the cumulative distribution of leaf area in the crown. It has the potential to be included in forest growth models where an accurate description of leaf area distribution is needed. A novel process-related, non-carbon-based growth model for predicting the growth of closed, unthinned, loblolly pine stands was developed. Its ability to represent the dynamics of the canopy and stand growth was evaluated. Overall, model predictions were in agreement with reported observations or proposed theories in relation to stand growth, size-density relations, and relationships between canopy dynamics and stand growth. Modeling the hydraulic architecture of the crown is important because it controls crown recession. Patterns in branch permeability with crown depth and permeability at the top of the main stem were analyzed for loblolly pine trees from families selected for differences in growth rate and crown size. The results showed that branch permeability decreased significantly from the top to the bottom of the crown and that genetic-based differences might exist in patterns of stem and branch permeability. The study showed the potential of using a process approach to develop a forest growth model and utilizing mechanistic and empirical elements in the construction of the simulator. In addition, the integration and synthesis of information coming from diverse sources in the model allow the possibility of detecting deficiencies in the understanding of key processes and provide a guide for formulating hypotheses and planning experiments to fill the gaps in knowledge of the processes regulating stand development.

Sperm from zebrafish, Danio rerio, and Nile tilapia, Oreochromis niloticus, were microinjected directly into egg cytoplasm to evaluate the potential for developing a novel method of fertilization. In zebrafish, the sperm of two lines (wild-type and gold, long-fin) were injected with or without activation into activated and non-activated eggs. No significant difference (P = 0.997) in fertilization by intracytoplasmic sperm injection (ICSI) was observed between the two lines or when the sperm were activated or not (P = 0.057). There was significance difference in fertilization between activated and non-activated eggs (P = 0.010). The highest fertilization rate was achieved by injection of activated sperm into non-activated eggs (35%). From a total of 188 zebrafish eggs injected, 31 (16%) were fertilized, 10 (5%) developed as abnormal larvae and 3 (2%) developed normally and hatched. Damage of maternal chromosomes by the injection procedure could have caused the developmental abnormalities observed after ICSI. This was investigated by fluorescence microscopy using a DNA-specific stain (Hoechst 33324). Fixed and stained animal poles of zebrafish 30 sec after artificial insemination revealed that female chromosomes were located ~40 mm from the sperm injection site (micropyle). Staining of the animal pole after sperm injection showed no disruption of the formation of the second polar body or its extrusion. Evaluation of two sperm injection sites in zebrafish showed no difference in fertilization rate (P = 0.8264) or reduction of abnormal development. Nile tilapia eggs placed in Hanks' balanced salt solution retained their viability for at least 3 hours after collection. Of a total of 160 Nile tilapia eggs injected with fresh sperm, 16 (10%) were fertilized, 10 (6%) developed abnormally to neurula and 5 (3%) developed normally and hatched, two of which reached adulthood. From 45 eggs injected with cryopreserved sperm, 9 (20%) were fertilized but none developed beyond blastula stage. Injections of sperm fixed in methanol did not yield fertilization. These results demonstrate for the first time that injection of single sperm cells into the cytoplasm of a fish egg allows fertilization and subsequent development of normal larvae to hatching and beyond.

Unlike most prairie nesting ducks (Anas spp.), the North American population of northern pintails (A. acuta, hereafter pintails) has failed to respond as expected to improved wetland conditions on the U.S. and Canadian prairies during the mid to late 1990s. My primary objectives were to test the ecological trap hypothesis on a landscape level by examining pintail nest site selection and nest success in a highly agricultural environment in southern Saskatchewan. I also used radiotelemetry to estimate renesting and breeding season survival rates of female pintails; two parameters that are important in productivity and life cycle models. Most (51%) pintail nests were found in crop stubble and generally pintails nested in habitats in proportion to their availability on the landscape. In contrast, most (82%) mallard nests were located in edge and grassland habitats. Mallards nested in habitats with dense cover in greater proportion to their availability and avoided crop stubble. Nest success estimates in crop stubble were lower (<1-4% vs. 6-37%) than the surrounding habitats with greater cover. Nest success estimates in crop stubble were abysmal largely due to high rates of nest predation. Only 20-33% of nests in crop stubble failed due to spring cultivation. For 1998, 1999, and 2000, overall renesting rates for females trapped throughout the nesting season were 50%, 71%, and 41%, but were 61%, 90% and 62% when only first nesting females were included. Renesting propensity declined seasonally, but at different rates among years likely due to variation in wetland abundance. Most (58%) females renested, but few (37%) initiated multiple renests. Survival rate for my 75-day interval (April 30 14 July) was 0.81 ± 0.05. Cause-specific mortality rates were greater for avian predators (0.14 ± 0.04) than other sources of mortality. The pintails high propensity to nest in crop stubble where nest success is low coupled with lower renesting and breeding season survival rates than mallards may partially explain their meager response to improved wetland conditions. Management programs to facilitate pintail recovery should be targeted at increasing nest success by providing safe nesting habitat.

Age ratio estimates obtained annually by the Cooperative Waterfowl Parts Collection Survey (PCS) serve as important estimates of annual waterfowl recruitment. To determine if age and sex ratios are biased due to repeat sampling of hunters across years, I examined PCS data collected from 1991-2000. Mean seasonal harvest increased with number of consecutive years hunters responded to the PCS. Proportions of juveniles in the mallard (Anas platyrhynchos) harvest and harvest of all species combined decreased with increasing seasonal harvest level. Proportions of males in the harvest increased with increasing harvest level. Proportions of juveniles in the harvest of hunters responding to the PCS 3 and 4 consecutive years were slightly lower than proportions in the harvest of hunters responding only once or twice. Proportion of males in the mallard harvest increased with number of years hunters remained in the PCS. Although large sample sizes produced statistically significant effects (P < 0.05) of seasonal harvest and repeat sampling, actual differences in predicted proportions were quite small. My results suggest that age and sex ratio estimates remain relatively unaffected by repeat sampling in the PCS.

This dissertation seeks to explore the effects of abiotic factors [nitrogen (N), sodium chloride (NaCl), and ultraviolet (UV) light], biotic factor [acetylsalicylic acid (ASA)], and plant hormones [benzyl adenine (BA) and naphthalene acetic acid (NAA)] on growth, morphology, and secondary metabolite, camptothecin (CPT, an anti-cancer compound) accumulation in Camptotheca acuminata. Five experiments were conducted with C. acuminata seedlings in a hydroponic system with commercial media and fluorescent lights and at 22-26 °C to investigate the effects of these five factors on height, weight, leaf number, leaf length, root to shoot ratio (RSR), specific leaf weight (SLW), CPT concentrations in leaves and/or roots, and final CPT yield in leaves which were collected in nondestructive harvestings. N deficiency decreased height, weight, leaf number, leaf length, and leaf chlorophyll concentration in comparison with N supplementation, but increased RSR, SLW, and CPT concentrations in leaves and roots. However, the CPT yield did not increase. NaCl addition reduced height, weight, leaf number, and leaf length, but increased SLW and CPT concentrations in leaves and roots. However, the CPT yield decreased. UV light short-term exposure had no effect on height, weight, leaf number, leaf length, RSR, and SLW, but increased leaf CPT concentration and yield after three weeks. ASA addition reduced plant height, weight, and leaf length, but increased SLW and leaf CPT concentration, and decreased CPT yield. BA application decreased height, but increased RSR and leaf CPT concentration, and had no effect on CPT yield. NAA application decreased height, weight, leaf number, leaf length, SLW, and CPT yield, but increased RSR, and had no effect on leaf CPT concentration. In conclusion, abiotic and biotic stresses reduced the growth and affected the morphology of C. acuminata seedlings in a hydroponic system. Abiotic stresses and biotic stress increased CPT concentration, but did not increase CPT yield (expect UV). Cytokinin up-regulated CPT concentration but had no effect on CPT yield, whereas auxin did not regulate CPT concentration but decreased CPT yield. A negative relationship between plant growth and CPT concentration existed under the treatments with N, NaCl, or ASA.

Due to its high market value, Florida pompano (Trachinotus carolinus) has long been regarded as a promising species for aquaculture. Although pompano exhibit several favorable traits for culture, previous studies have indicated that fish larger than 200 g exhibit poor growth. This study was conducted to determine the effects of different feeding strategies on production characteristics of pompano raised in closed recirculating systems. Results of Experiment 1 indicated that mean weight of fish (initial mean weight, 17 g) fed a fixed ration at two and six feedings per day was greater than that of fish fed only once per day. Weight gain of fish fed twice per day was greater than that of fish fed once per day. Results of Experiment 2 revealed that growth was not greatly affected by the stocking densities evaluated (1.3 and 2.6 kg/m³). However, mean weight and weight gain of fish (initial mean weight, 74 g) fed to satiation were greater than that of fish fed a fixed ration and reared at the low density. Results of Experiment 3 demonstrated that mean weight and weight gain of fish (initial mean weight, 215 g) reared to market size while receiving four feedings to apparent satiation per day was greater than that of fish receiving two feedings to apparent satiation per day. Whole body composition analysis revealed exceedingly high lipid levels of fish throughout the study. Market size pompano had dressed carcass yields greater than 70% and fillet yields greater than 45%. Feeding strategies used in this study had little, if any effects on feed efficiencies and specific growth rates. Survival of fish in each experiment was greater than 90%. Growth of pompano in this study was not restricted to 200 g. Pompano achieved market size after approximately 4.5 months and reached an average weight of 712 g after approximately 8.5 months. Our results show that market-size pompano can be grown from juveniles in closed recirculating systems under the conditions used in this study.

I examined the accuracy of using data collected by temperature sensing dummy eggs (hollow and switch) to determine female nest attendance in waterfowl. I monitored 3 northern pintails (Anas acuta) and 6 mallards (A. platyrhynchos) using closed circuit video recording. Differences in the time spent on the nest for an 8-hour recording period between dummy eggs and camera were similar between type (hollow and switch eggs, P = 0.93), species (P = 0.07), and date (P = 0.42). My results show that temperature data from hollow and switch eggs are an effective and accurate method to monitor female nest attendance for prairie-nesting waterfowl. I investigated the effects of nest site cover and nest site temperatures on the patterns of female nest attendance in pintails and mallards. I monitored nest attendance of 82 pintails (1094 days) and 94 mallards (761 days) in North Dakota in 2000-2001 using temperature sensing dummy eggs in nest bowls. Time spent on the nest per day (constancy) was lower for pintails (81.6 ± 0.31%) than mallards (83.2 ± 0.46%; P = 0.03), and pintails took more recesses per day (2.64 ± 1.07) than mallards (1.77 ± 1.07, P < 0.001). For early nesting pintails and mallards, constancy decreased with increasing nest site cover (lateral concealment) and increased slightly for late nesting females (P < 0.01). However, experimentally adding or removing nest site cover at mallard nests did not affect constancy (P = 0.13). For both species, females spent more time on the nest late in incubation when it rained than when it did not rain (P = 0.02). Pintails spread their incubation recesses more evenly over the daylight period than mallards, which concentrated their recesses in the evening (P < 0.001). Maintaining a higher constancy resulted in a shorter incubation period for pintails (P < 0.01) but not for mallards (P = 0.59). My results suggest that other factors such as body size and condition, or trade-offs between female condition and the risk of predation may influence female nest attendance in pintails and mallards to a greater extent than nest site cover.

The red snapper Lutjanus campechanus is an economically valuable sport and commercial fishery, and because of its high market value and limited commercial harvest, red snapper have received considerable attention as a candidate for marine aquaculture and stock enhancement programs. The goal of this thesis was to improve hatchery techniques for artificial spawning of red snapper Lutjanus campechanus. The objectives were to: 1) refine protocols for collecting, handling, transport, and holding of mature red snapper broodstock for induced spawning; 2) establish methods for strip-spawning of red snapper to optimize egg quality; 3) develop procedures for the collection, storage, and use of refrigerated and cryopreserved sperm of red snapper and gray snapper, and 4) evaluate the overall effects of gamete and larval quality on rearing success. The techniques developed were practical methods that hatchery managers can use to collect high-quality broodstock, to preserve sperm, and to collect and incubate eggs. Red snapper broodstock (N = 101; 1.0 to 3.8 kg) were collected during the 2000 and 2001 spawning seasons (May to August) off coastal Louisiana by hook and line sampling. The reproductive condition of females was evaluated through samples of oocytes collected by intraovarian biopsy. Females with oocytes ranging in size from 350 to 550 µm were considered good candidates for hormone induced spawning. Female snapper were induced to ovulate with injections of human chorionic gonadotropin. Females were monitored for oocyte maturation and were stripped after ovulation. In a series of 2 x 2 trials, refrigerated and cryopreserved sperm with motilities above 80% were compared to evaluate fertilization and hatching success. Eggs were incubated in plastic bags (200 eggs per L) and fertilization was assessed as embryos developed through 8-cell, neurulation, and hatch. Fertilization and hatch rates ranged from 7 to 99% and were highly correlated (r2 = 0.92). Refrigerated sperm yielded fertilization rates of 52 ± 23% (mean ± SD) and cryopreserved sperm yielded fertilization rates of 44 ± 22%. Use of refrigerated and cryopreserved sperm improved efficiency within the hatchery and each were effective for the fertilization of eggs and production of larvae.