Dissertations / Theses on the topic 'Discus (Fish)'

This study assessed the occurrence and impacts of maternal metal transfer in live-bearing fish. The occurrence was investigated in two different species (Gambusia affinisand Heterandria formosa), while the impacts were studied only in G. affinis. Occurrence and impacts were addressed by exposing gravid females for 10 days to 0.15 μM of copper or cadmium, transferring the fish to clean water, monitoring their reproduction and collecting newborn offspring for further analyses of their health and reproductive success.

Maternal transfer of copper and cadmium occured in both study species. Metal levels decreased in subsequent broods and in broods born later after a female's exposure. Metal exposure impacted the reproductive success of exposed-females; effects included smaller broods and more broods were aborted broods or contained dead offspring. Many effects remained for second broods developing well after the exposure.

The maternal metal exposure also impacted the offspring's health. Newborn offspring were smaller at birth, had reduced calcium levels, had a lowered metal tolerance, and had cellular membrane damage. When these offspring grew up, they had an increased rate of malformations, a smaller size at sexual maturity, increased gestation time and fewer broods. In spite of the impacts on life history parameters found in the laboratory, effects on population dynamics were very limited for greenhouse mesocosm populations established with the offspring of exposed females.

Effects for the essential metal (copper) and the nonessential metal (cadmium) were generally similar. A few effects, like those on body size, were evident for copper but not for cadmium. However, several of the more severe impacts, like the increase in malformations and reductions in the number of broods, were greatest for the offspring of the cadmium-exposed females.

This is the first report demonstrating negative impacts resulting from a short-term maternal metal exposure in live-bearing fishes. Effects were evident not just for reproduction of exposed-females but also for their offspring's health and reproduction. The latter continued beyond the offspring that were developing during exposure. This study demonstrated that the internal development in live-bearing fish may not spare the developing young from impacts caused by a metal-contaminated environment.

River herring, the collective name given to North American populations of Alewife (Alosa pseudoharengus) and Blueback Herring ( A. aestivalis), are iteroparous, anadromous members of the family Clupeidae, with similar morphology, ecological roles, and overlapping distributions. Once abundant in coastal rivers of New Hampshire, many factors including commercial fishing, habitat degradation, and dam construction resulted in a precipitous decline of the species along the entire coast. Successful efforts to restore populations have included the construction of fish ladders at dams. However, fish ladders require constant operation and maintenance to efficiently pass river herring, and only provide access to spawning habitat up to the next barrier, all too often, man-made.

Alewife passage efficiency in fish ladders of all designs has received little attention historically, but is important to understand how to interpret annual counts, that for many rivers are the only index used in current stock assessments. In this study, passive integrated transponder (PIT) tags were used to assess the passage efficiency of a Denil fish ladder on the Lamprey River in Newmarket, New Hampshire. The data collected allow for a better understanding of the movements and diel behavior of river herring in fishways, as well as insight into how the selectivity of fish ladders my shape the population demographics within a river system.

A breached dam located at Wadleigh Falls on the Lamprey River in Lee, New Hampshire was examined to determine if river herring were able to pass the existing structure or if it should be considered the upper extent of their annual spawning migration. Telemetry data indicated that Alewives were unable to pass the breached Wadleigh Falls Dam site and that it should be considered the uppermost extent of their migratory access. Results also show that migrating fish arriving at the location had a strong preference for the river-right channel when migrating upriver and exhibited very little exploratory behavior to seek alternate pathways upriver before emigrating back downriver, approximately two weeks after river entry. These in-river residence times were very similar to those found in other telemetry studies of anadromous Alewives.

Successful management and effective stock assessment for any species requires an understanding of its reproduction and recruitment. Fecundity is one measure of the reproductive potential of a species and was assessed in this study. Mature adult Alewives were collected at the head-of-tide dam on the Lamprey River in Newmarket, New Hampshire during the vernal spawning migration in 2012. A gonadosomatic index was used to determine that fish were sampled before spawning occurred, and egg diameters were quantified to examine distribution of eggs throughout the ovary. Fecundity was estimated gravimetrically using two techniques for comparison, and no difference between the methods was found. These findings show that image analysis is a fast and reliable method for fecundity estimation that does not require the use of a commonly used, toxic solution for ovary preservation. Fecundity estimates using image analysis ranged from 147,400 eggs at 24 cm to 332,500 eggs at 34 cm and aligns with previous findings of a clinal trend along the Atlantic Coast. Fecundity increased with total length, somatic weight, and age. Simple linear regressions exhibited good fits for fecundity-total length and fecundity-somatic weight, with age being the best predictor.

The non-local fish-bone potential simulates the Pauli-exclusion principle for composite particle interactions. This model is used to calculate the phase shifts of the neutron-alpha and proton-alpha systems. We propose a local double Gaussian potential with a new parameterization by fitting to experimental results. These parameters are universal to both nucleon-alpha systems and include all partial waves, which is an improvement over previous work in the field.

Researchers on the Northwest Coast (NWC) are often interested in complex questions regarding social organization, resource intensification, resource control, and impacts of environmental change on resources and in turn human groups. However, the excavation strategies used on the NWC often do not provide the spatial and chronological control within a site that is necessary to document their variability and answer these research questions. The Čïx ^wicen site has the potential to address some of the limitations of previous Northwest Coast village site excavations because of its unique and robust sampling strategy, the wide expanse of time that it was occupied, and the multiple house structures present. An on-going project is examining changing human ecodynamics over the breadth of site occupation, focusing on zooarchaeology and geoarchaeological records.

This site, located on the Strait of Juan de Fuca in Port Angeles, WA was excavated in 2004 as part of a Washington State Department of Transportation (WSDOT) undertaking to build parts for the Hood Canal Bridge Large scale excavation (261.4 m³ 528 m²) generated enormous quantities of faunal remains. Radiocarbon dates and historic records show occupation extends from 2750 cal. BP to the early 20^th century.

Statistical sampling methods provide an empirical way to maximize the amount of information obtained with the least amount of effort. My thesis addressed the utility of Sampling to Redundancy (STR) as a statistical sampling method for sampling faunal remains from large village sites. My project has documented the variability of fish family representation across time and space in one part of the Čïx^wicen village, while minimizing the time and effort required to do so. This thesis applies STR to “S” (> 1/4 in.) 10 Liter bucket samples from eight excavation units and a total of 26 separate unique temporal and spatial contexts. I focused on 1/ 4 in. samples for my study for a particular reason. Previous fish faunal studies have focused on effects of mesh size on fish representation; and emphasized the need to use fine mesh (e.g., 1/ 8 in. or finer) to document small-bodied fishes. This focus on fine mesh typically means that only limited volumes of matrix are studied, which in turn may mean that remains of rarer, large- bodied fishes are under- represented. The on-going research project has focused on buckets screened to 1/ 8 in. mesh (called “C” buckets). I used STR to sample additional volumes of matrix screened to 1/ 4 in. to examine whether expanding the volume studied would affect fish representation, which was a second goal of my project.

Overall, I studied remains from 269 “S” buckets out of a total of 419 buckets, or 47% of the buckets. STR was most helpful for six of the high bone abundance and density contexts, where I analyzed less than 50% of the total buckets, was moderately helpful for 14 contexts, and not at all helpful for the six contexts with low fishbone abundance, where I analyzed 100% of the buckets. This analysis took me a total of 154 hours, and based on the percentage of material analyzed, 174 hours were saved.

As to the second project goal, to assess whether adding fish remains documented from additional matrix volume affected fish representation, I found the differences were minimal. Both for my study units as a whole, and for each time period, adding the fish records from the “S” buckets did not alter the main trends in fish representation as documented by the larger study, using a smaller volume. To further examine whether the added volume from >1/ 4 in “S” buckets affected results, I explored specific research questions that are relevant to the larger project regarding environment-animal interactions and fishbone deposition and bone condition inside and outside of a house structure. Adding the “S” bucket samples did not affect fish representation or fishbone distribution and condition, which affirms that the sampling strategy used in the larger research project was sufficient in most cases to characterize the fish record at the site.

My approach to STR has focused on fish remains that were previously excavated from a Pacific coastal village site with dense archaeological deposits. STR could be employed in other types of archaeological settings in a range of environments (coast or interior) representing a range of cultural contexts (from hunting camps to urban centers) to establish sample redundancy after an excavation is complete. STR could be used during on-going excavation. Further research is required to explore the implications of STR in these settings, however it is likely that the success of STR in other contexts will be dependent on the density and overall abundance of remains, the diversity or material types being studied, as well of course in the range and specificity of questions in each case.

This study assed the impacts of 17α-ethinylestradiol in Heterandria formosa. These impacts were addressed through chronic, life-cycle exposures of individuals and populations of least killifish to 0, 5, or 25ng/L EE2. Development, growth, reproduction, survival, and population dynamics were monitored and evaluated for EE2 effects on their health, reproductive success, and population sustainability.

Exposing pairs of least killifish to EE2 resulted in similar increases in time-to-sexual maturity for both sexes. The EE2-exposure had a sex-dependent effect on body size, with standard lengths and wet weights of females significantly reduced and standard lengths of males markedly increased. Offspring production decreased by 50% and 75% for fish exposed to 5 and 25ng/L EE2 respectively. Sexual development was even further delayed in EE2-exposed offspring of exposed fish. EE2-exposure also affected the gonadal and liver development in least killifish. Males exposed to EE2 had delayed sperm maturation and severe intersex (a phenomenon in which eggs and sperm are produced within the same male). These effects were more severe at the 5ng/L than at the 25ng/L EE2 concentration. Exposing females to EE2 resulted in delayed egg maturation. Furthermore, EE2 exposure resulted in changes in liver morphology in both males and females. For both the delay in egg maturation and the changes in liver morphology, the effects were strongest at the higher EE2 concentration.

Effects of chronic EE2-exposure on populations were assessed at the 5ng/L concentration. EE2-exposure caused significant reductions in population size and population growth rates, and caused other changes in population dynamics. Exposed populations had a pronounced female-biased sex ratio and significantly reduced abundances of males and newborns. These responses were observed within one breeding season.

This is the first report demonstrating a variety of negative impacts resulting from chronic EE2-exposure in least killifish at both the individual and population levels. Effects were evident in all stages of development and in all life history stages. This study demonstrated that, similar to the case for other fish, live-bearing fish are likely to be severely affected when their environment becomes contaminated by EE2 and that steps are needed to prevent exposure to this endocrine disrupting chemical.

The South Texas Banks are a mesophotic coral ecosystem (30-150m deep). Understanding the community structure, biodiversity and, geographic connectivity of the South Texas Banks is essential with increasing threats from climate change, ocean acidification, invasive species, and pollution. In this study, a remotely operated vehicle (ROV) was used to examine the fish communities at five of the South Texas Banks: Big Adam, Hospital, Mysterious, North Hospital, and Southern. Reef fish were identified to the lowest possible taxon and enumerated from ROV transect video footage. A total of 3,838 demersal and pelagic fishes were recorded representing 61 species in 22 families including invasive Pterois volitans. Bodianus pulchellus, Holocentrus adscensionis, Priacanthus arenatus, and the Gobiidae family were the only fishes observed at all five banks. Habitat suitability models were created that highlight the rich biodiversity found on the South Texas Bank, which will warrant for future research and conservation efforts.

A diet rich in omega-3 fats has been shown to reduce the risk of cardiovascular disease. Long chain omega-3 fats found in fatty fish are especially important to cardiovascular health. Consumption of these fats is low, in part because there are few natural sources. This has led to the development of omega-3 fortified foods. Currently available fortified foods demonstrate conflicting nutritional information. Addition of omega-3 fats to an otherwise unhealthy food is perceived by consumers as an advertising gimmick. Mistrust of food companies and confusing ingredient labels negatively impact sales. Careful nutritional guidance, combined with proper sensory analysis, is critical to developing omega-3 fortified food products that are consistent with medical recommendations. Results from this study indicate that a therapeutic dose of fish oil (1000 mg per serving) can be added to two heart-healthy foods without adversely affecting sensory qualities.

Although dawn and dusk periods comprise a relatively small part of the day, their importance as key ecological transition periods has been recognized for some time. Previous marine investigations into this transition have focused on tropical locations and have mostly been qualitative in nature. This project focused on the dusk period in sub-tropical reef fish communities off the coasts of North and South Carolina. High-definition underwater video was collected in 2013 and 2014 at a variety of sites featuring natural live-bottom habitat. Independent samples (43 videos) were obtained on 17 sampling dates. Fishes were tallied by time relative to sunset (TRTS) in an effort to identify temporal abundance patterns and categorize taxa by temporal niche. Sufficient data were collected for statistical analysis of 27 taxa, representing 15 families. Analyses explored whether there was a relationship between time and abundance. Of the taxa analyzed, ten showed no temporal pattern during the dusk period, seven showed abundance peaks during dusk, and ten showed declines in abundance during dusk. Patterns were not always consistent within families. In particular, the Serranidae and Sparidae families featured a variety of patterns. Uncommon species and ephemeral behavioral events were also noted and described.

Animals that live in groups face a dual challenge of effectively exploiting their environment while at the same time maintaining cohesion with other group members. Maintaining cohesion requires group members to come to consensus about when and where to move, despite the fact that they may not always agree. In this thesis, I investigate how individuals in groups make movement decisions, and how these individual decisions scale up to group-level properties. Using a laboratory experiment with golden shiners (Notemigonus crysoleucas ), I first investigate the interaction network over which information spreads, finding that decisions are better predicted by whom individuals can see rather than whom they are close to, with potential consequences for the global spread of information (Chapter 2). I then investigate collective movement behavior in the wild using high-resolution GPS data from members of a troop of olive baboons (Papio anubis). I first show that baboons are consistent in the spatial positions they occupy within the group, and that the observed patterns may be understood based on a very simple mechanism by which individuals maintain cohesion with different numbers of their neighbors (Chapter 3). By quantifying how group members move relative to one another, I then show that baboon movement decisions are consistent with a shared decision-making process, rather than despotic leadership by dominant individuals, and that the patterns of decision-making are consistent with simple models of collective motion (Chapter 4). Finally, by incorporating a fine-scale, three-dimensional reconstruction of the habitat through which the baboons move, I show that habitat structure, in addition to social factors, also exerts an important influence on individual movement decisions, resulting in changes in the emergent structure and movement of the group (Chapter 5). Taken together, these results highlight that by combining high-resolution animal tracking, remote sensing, and analytical methods, we can begin to extend our understanding of collective animal movement from laboratory studies to complex animal societies living in the wild.

Relying on field research to complete the life history for certain fish species can be inadequate, but laboratory research can be used to fill these gaps. These gaps exist for Bonefish (Albula spp.), a tropical marine fish and popular sportfish. In this study, aquaculture techniques were applied to Bonefish in a captive setting at Harbor Branch Oceanographic Institute (HBOI) and Cape Eleuthera Institute (CEI) to induce spawning and describe early ontogeny. Photothermal manipulations and hormone injections were used to induce gonad maturation and spawning, which was achieved once at CEI and is the first record of hormone-induced spawning for Bonefish. From that spawn, egg and larval development were recorded and described through 26 hours and 56 hours respectively, representing the first record of these early life stages for Bonefish. This work expands upon what is known about Bonefish reproductive biology and will be useful for management and future captive research.

The predominant method to quantify reef fish populations is the Open Circuit SCUBA (OC) in-situ fish survey. However, there are many biases associated with these surveys including the expelled OC exhaust which can cause visual and audible disturbances. This study aims to evaluate the bias created by OC exhaust utilizing closed-circuit rebreather (CCR) surveys, along surveys were conducted in protected areas and fished areas. The three sites in the main Hawaiian Islands were Kealakekua Bay (KK), Old Kona Airport (OA), and Pūpūkea (PK) marine life conservation district. This study found that the total fish biomass and species richness from all sites pooled showed no significant differences between gear types. However, there was a significant interaction between the gear type and the protection status (Pr(>|t|) = 0.025), indicating that there are greater differences between OC and CCR in the fished areas than the protected areas. The difference between the gear types showed a greater magnitude of OC having a higher biomass in the fished areas opposed to the protected areas where that difference was smaller. When fished species (Table 4 – a, b) were examined, significant differences between gear types were shown (Pr(>|t|) = 0.010). The OC surveys showed more fished biomass than the CCR surveys which could mean that the attraction to the exhaust within the protected areas were greater than the repulsion of the exhaust in the fished areas. Differences in the fished species biomass while having no difference in the all fish biomass supports the previous studies findings that fishing pressure is very influential on the magnitude of difference between the gear types. For researchers, estimating fishing pressure is of high importance in order to assess the level of bias associated with OC exhaust on surveys. These biases need to be accounted for in population estimations for protected areas and non-protected areas in order to get more accurate biological fish data.

Marine Protected Areas (MPAs) are successful place-based management tools in protecting Essential Fish Habitat (EFH) from commercial and recreational fishing pressures. In the southeast Atlantic, the morphometric environment of the seafloor has been found to be a control on Essential Fish Habitat (EFH) (Sedberry and Van Dolah 1984). To this end, modern methods of acoustic data acquisition and morphometric analysis of the seascape are promising oceanographic techniques for identifying and delineating EFH. In July, 2013, the NOAA Ship Pisces collected bathymetric, backscatter and water column data for potential habitat sites along the U.S. Southeast Atlantic continental shelf. A total of 205 km² of seafloor were mapped between Mayport, FL and Wilmington, NC, using the SIMRAD ME70 multibeam echosounder system. In addition, a total of n = 7410 fish presences were recorded within the water column, using the SIMRAD EK 60 split-beam echosounder system. These data were processed in CARIS HIPS, QPS Fledermaus, MATLAB and Echoview. This study provides a morphometric characterization and quantitative assessment of fish present within each survey site and identifies features of the bathymetry that help explain the presence of demersal fish. A total of 106 unique maps were created, illustrating seafloor morphometrics and fish distributions across the seascape. In ArcGIS, 14 morphometrics were generated as candidate explanatory variables for fish abundances in small (5-12 cm), medium (12-29 cm) and large (>29 cm) size classes. We explored fish-seascape interactions at two spatial scales in the GIS using a site-wide and 50 x 50 m grid scale. At the site- wide scale, X¯ Slope (R² = 0.97), X¯ Slope of Slope (R² = 0.90) and σ Depth (R² = 0.87) provided the strongest explanatory power in a bivariate analysis and may be used to help identify EFH at a coarse scale. At a 50 x 50 m grid scale, X¯ Slope, X¯ Slope of Slope and X¯ Backscatter emerged as the strongest contributing variables, when combined in a multivariate analysis. Overall, multivariate model R² values were low and not predictive, but allow for the identification of variables contributing to the characterization of fish-seascape interactions at a finer scale.

Marine Protected Areas (MPA) are broadly used to protect marine ecosystems, restore biomass, and increasingly as tools in fisheries management for benthic stocks. Nevertheless, MPAs are seldom used to target pelagic species due the challenges of designing an effective MPA in a highly dynamic environment. It is believed that highly mobile organisms will get few benefits, since they leave the protected area too frequently. One possible solution is to compensate for such movement with larger MPAs. Nevertheless, uncertainty about the benefits in the face of vagaries about fish movement make it unlikely that such efforts would be successfully pursued.

Although it is a generally accepted that MPAs provide multiple benefits if well designed, empirical demonstrations of benefits from MPA are hard to obtain. They require long term evaluations, and as a consequence, comparisons between alternative MPA designs are almost nonexistent. Simulation models provide an alternative to empirical approaches that allow tests of designs and forecasts of potential outcomes. To date, most of the simulation models of MPAs have been developed for benthic systems, where simplified assumptions about fish and fisherman movement are reasonable. Fortunately, with the advent of more realistic fish movement models, new approaches are now possible that can combine complex individual-based models of movement, population dynamics and virtual MPA systems. The use of these new complex simulation models can guide the optimization of MPA design to increase both stock sizes and fisheries yields.

The goal of the research presented in this dissertation is to study the potential of a large MPA to protect a pelagic stock and determine how fish movement characteristics and complex environmental dynamics influence the optimal design criteria for a successful pelagic MPA. The findings are timely given increasing interest in developing large no fishing zones to protect overfished pelagic stocks, especially for those taxa whose distribution spans more than one exclusive economic zone or resides in international waters. For this purpose I implemented a simulation model that incorporates detailed fish movement and their responses to complex environmental forcing to study the effect of fish movement on the efficacy of MPAs of different size and location. (Abstract shortened by ProQuest.)

The Magnuson-Stevens Fishery Conservation and Management Act (MSA; Magnuson-Stevens Fishery Conservation and Management Act. 2014. (16 U.S.C. 1801–1891(d)) mandates that fisheries management councils in the United States prevent adverse, or “more than minimal and not temporary”, fishing effects to essential fish habitat (EFH) to the extent practicable. Councils were left to decide what effects qualified as “minimal” and “temporary”. The lack of explicit definition in the MSA and its accompanying Final Rule has resulted in inconsistent habitat management throughout the country. The EFH mandate was written under an implicit assumption that councils have the scientific information necessary to effectively manage EFH. Basic information is lacking, such as what type of habitat occurs where, and how fishing effects habitat features. Chapter 1 briefly reviews the history of EFH regulation, the consequences of regulatory ambiguities and information gaps, and highlights that high latitude fisheries management can be disproportionately affected by climate variability. Thus, requiring investment in baseline habitat assessment and monitoring and renewed focus on under developed areas of research e.g. Fishing effects and gear-habitat interactions.

Councils have attempting to quantitatively describe fishing effects to EFH through the use of mathematical models. The most recent of which, the Fishing Effects (FE) Model, was used in the North Pacific Fisheries Management Council 2015 EFH Review cycle. The FE Model uses discrete time steps (monthly) and spatially explicit fishing effort and sediment data to calculate an estimated habitat disturbance. The FE Model is calculated in two-dimensions and implicitly assumes that if fishing gear does not contact the seabed, then there is no gear-habitat interaction. Some features stand taller than raised gear (e.g. sea whips, Halipteris willemoesi, in the North Pacific can up to 2m tall) and may interact with fishing gear. The FE Model in two-dimensions does not account for this potential interaction and cannot effectively simulate gear modifications. Chapter 2 proposes an adapted version of the FE Model that accounts for the vertical interactions through the use of discrete height bins. To accurately estimate interactions on and above the seabed, fishing gear has to be recharacterized. To demonstrate this the Bering Sea flatfish trawl was recharacterized by calculating how much of the nominal gear width is present in each height bin. A detailed methodology is provided to allow this method to be applied to any fishing gear. The adapted FE Model can be used to simulate gear modifications, as is shown by simulating two modifications of the flatfish trawl. This chapter will inform the 2020 EFH Review cycle as the FE Model is improved.

Limited information exists on how southern Californian restored estuaries affect fish habitat use. I used the movements of five predatory fishes in two guilds (ambush and roving predators) to assess juvenile habitat use within estuaries and across landscapes at two spatial scales. Translocating fishes between two discrete estuaries located approximately I 0 km apart revealed that connectivity potential between sites differed between foraging guilds. Despite habitat design differences, fishes did not appear to prefer one site over the other. However on a smaller scale (e.g., within a single estuary), differences in microhabitat conditions affected the habitat use by California Halibut (Paralichthys californicus). Individuals selected habitat based on water flow velocity, temperature and eelgrass coverage, but utilized habitat conditions in a size-segregated manner. Since restoration habitat design influences available microhabitat conditions, differences in design likely alters space use within restored estuaries although perhaps not estuary selection itself.

Mycobacterium marinum (Mm) shares at least 80% amino acid sequence identity with over 3,000 orthologous genes of Mycobacterium tuberculosis (Mtb) and is thus used as a surrogate pathogen for Mtb research. Our laboratory investigates mycobacteriosis using Japanese medaka ( Oryzias latipes) as an aquatic animal model. Mm disease presentation in medaka is similar to Mtb disease presentation in humans, including growth in macrophages, granulomatous lesions, and lifelong chronic disease. We have previously shown that a major route of infection in fish is through an oral route and have thus developed methods to infect medaka with Mm utilizing mosquito larvae as vectors. Recently, our lab was able to show that Mm is able to cross the gut epithelia of medaka in a relatively short-time frame and travel to the underlying submucosa. Therefore, Mm must have the ability to attach to the gut mucosal layer and evade killing by GALT immune cells. Mm is apparently able to exploit macrophages of the mucosal immune system to transport the bacteria to target organs like the head kidney, liver, and spleen for a systemic infection. Utilizing an Mm strain engineered to carry a deletion in the RD-1 region, known to include a number of virulence genes, our lab has shown that mucosal immunity against Mm can be induced in medaka. We have shown that exposure to the mutant RD-1 strain offers some protection against a chronic wild-type oral challenge. Since we know that mutant RD-1 can elicit a mucosal immune response, I tested to see if sensitizing mucosal immunity would also induce systemic immunity by first priming fish with mutant RD-1 and then subsequently challenging them with wild type Mm via an IP route. This thesis demonstrates that mucosal immunity is limited to the gut and thus does not appear to provide broad systemic immunity. Additionally, I tested to see if systemic vaccination would protect against a systemic virulent wild-type challenge by vaccinating and challenging fish via an IP route of infection. Results showed that systemic vaccination does not induce systemic immunity and thus does not protect against an IP injected virulent challenge. Collectively, results from this thesis have shown mutant RD-1 to only be effective as a vaccine against mycobacteriosis if given orally since it was shown to only induce a mucosal immune response and only be protective against an oral virulent wild type challenge.

Two types of unusual concretions with similar contents but markedly different shapes and distributions were found in close stratigraphic proximity within the Whitmore Point Member of the Moenave Formation. Roughly cylindrical, elongate concretions were found in parallel and regularly spaced rows, and a layer of irregularly shaped and distributed fossiliferous concretions was discovered only a few centimeters above the cylindrical concretions. Both sets of concretions contain abundant hematite as well as enameloid fish scales. In addition, the concretions contain numerous ostracod carapaces and what appear to be rip-up clasts. Microprobe and Raman analyses of representative concretion samples reveal that the cylindrical concretions have a groundmass largely composed of silica while the irregular concretions have a groundmass largely composed of dolomite, and the ostracods within each type of concretion have been altered and match the chemistry of the surrounding groundmass. Evidence of multiple cement precipitation events is present within each concretion. These unusual concretions suggest mass fish mortality events in the large lake that occupied the St. George area in the early Jurassic.

To evaluate the success of reestablishing tidal connection to salt marshes as a method of creating new fish habitat, both newly-restored and previously-restored (hereafter termed "reference") habitats within the Huntington Beach Wetlands Complex were monitored over a two year period. Although fish abundance and diversity metrics were generally equivalent between marshes within one year, community composition remained different. Newly-restored habitat generally had higher abundances of planktivores (e.g., Atherinops affinis), and lower abundances of benthic carnivores (e.g., Fundulus parvipinnis ) relative to reference habitat. To determine the possible mechanisms driving fish habitat use patterns, trophic support was assessed for juvenile California halibut, Paralichthys californicus, using gut content and stable isotope analyses of wild-caught and caged individuals. Observed differences in the diet of halibut across size classes indicated ontogenetic shifts in feeding behaviors, while similarity in diet among marshes suggested the potential for rapid development of trophic support within restored habitats for this species.

Reservoirs throughout the country exhibit degraded shorelines and simplified littoral habitats because of aging. This study evaluated the establishment of agricultural plantings on reservoir mudflats and the effectiveness of supplemental brush pile structures in providing recruitment habitat for juvenile fish. The mudflats of Enid Reservoir, Mississippi were seeded during the winter drawdown in October of 2016 and 2017 with agricultural plantings. Monitoring of plantings found grasses performed best in terms of establishment and providing potential fish habitat. During Summer 2017 brush piles and control sites, without brush, were sampled in Enid Reservoir using rotenone to evaluate juvenile fish use. Juvenile fish exhibited greater abundances and larger sizes, on average, in brush pile sites. Larger brush piles placed in shallower water provided the greatest benefit to juvenile fish.

Mycobacterium marinum is an established surrogate pathogen for Mycobacterium tuberculosis because of M. marinum 's strong conservation of thousands of orthologous genes, lower risk, lower financial burden to researchers, and similar pathology in fish. This pathogen causes TB-like chronic disease in a wide variety of fish species and can mount superficial infection of human tissues. As in human TB, the microbe grows within the host macrophages, can mount life-long chronic infections, and produces granulomatous lesions in target organs. One of the fish species known to manifest chronic "fish TB" is the small laboratory fish, Japanese medaka (Oryzias latipes). Recently, our lab documented the progression of the bacterium from the lumen of the gut to underlying tissues and to target organs to mount infection. Since the bacterium can be observed crossing the epithelia to mount infection, I tested to see if mucosal immunity against a wild-type challenge could be induced by initially priming the fish to a live, attenuated vaccine strain. This thesis demonstrates that inoculation by ingestion is an efficient mode by which medaka can become infected and vaccinated with M. marinum. Furthermore, my thesis shows that orally vaccinating fish with a live, attenuated strain indeed provides protection in the gut, liver, and kidney against a virulent, wild-type challenge.

This research investigates why typical strategies for promoting health, prolonging life, and preventing disease do not work in many communities. I use the liver fluke infection endemic in Khon Kaen, Thailand to explore the middle ground between Western science and Eastern culture. Prior work on the O.viverrini infection in Khon Kaen, Thailand has focused almost exclusively on developing effective medical treatment for the liver fluke infection. This dissertation employs a case study designed to explore the conditions that created and perpetuate the problem in the first place. In concrete terms, I analyze how the worldviews of local villagers shape their attitudes toward life (and death), which in turn determine if they engage in the high-risk behavior – eating undercooked fish – that makes them vulnerable to the infection. My research focuses on these people in-situ over a three-month period, and includes data from participant-observation, interviews, and video-recordings. This work seeks to illuminate how people’s thinking and reasoning skills, and personal/cultural identities affect their abilities to learn and act on new health concepts. This potentially provides a window into future educational strategies in a complex world.

ABSTRACT Numerous studies have been undertaken on the political economy of agricultural policies in developing countries. These studies have explained agricultural policies in terms of urban bias, economic reforms, and domestic politics. Recently, the emphasis has been on explanations that reference the existence of a rational-legal and patronage element within the African state. Such explanations tend to underplay the extent to which agricultural policies are devised in a context of power asymmetries between the state and international donors or financial institutions. In the Malawian context specifically, limited attention has been paid to the possibility that policies are a negotiated outcome of interactions informed by competing objectives at the state-donor interface. Accordingly, the proposed study will attempt to fill this existing gap in the literature. Malawi is currently at the center of policy debates regarding the state?s capacity to launch a uniquely African Green Revolution within a marketized and capitalist configuration. Such debates mark the continued underinvestment in agriculture on the African continent. The Malawi case, therefore, provides a unique opportunity to explore the extent to which state level efforts are either confounded or enabled by donors and international financial institutions. The specific successes and failures of the Malawi case speak to the question of how other countries in Sub-Saharan Africa might successfully address food production and food security issues. This dissertation will explore the overarching question of the role of the state and international donors in shaping agricultural and food security policies using Malawi?s farm input subsidy program as a case study. The main research methods to explore this question are qualitative, including interviews with various development stakeholders (government ministries, international development agencies, researchers from policy research and academic institutions, and civil society organizations) associated with agriculture and food policy-making, and textual analysis of publications associated with them. The research specifically targets key experts in the area of agriculture and food security. The findings indicate that policies have been greatly influenced by the competing ideologies of the state and donors, with each recognizing the problem but differing on the approach and modalities for solving food insecurity in Malawi. To this extent, there has been considerable inconsistency in policies with obvious negative outcomes. More recently, there has been an aligning of policy positions towards the use of social welfare programs and commercialization in addressing food insecurity. This alignment relates to policy positions on both the FISP and the configuration of the wider agricultural sector as manifest in the National Agricultural Policy, for example. The role of domestic politics vs. donors in policy processes has been in flux due to changes in the political and economic environment and configuration at specific junctures. The study also finds that evidence has been important in informing policy-making, more importantly, finance has had significant impact in attenuating the influence of domestic politics, so that the recently proposed and implemented reforms to FISP, although connected to considerable sociopolitical pressure from various quarters, have been largely precipitated by a serious fiscal crisis on the part of the government. To this extent, the state has assumed a pragmatic approach to policy-making i.e., one that is cognizant of the limitations imposed by finance and Malawi?s very harsh, challenging, and complex context.