Na aquacultura de recirculação são utilizados filtros biológicos para o tratamento do efluente antes que este retorne aos tanques. Estas unidades de tratamento têm como finalidade a transformação de nitrogênio amoniacal em nitrato, pois a amônia e o nitrito são tóxicos para os peixes. O nitrogênio amoniacal tende a se acumular na água de cultivo, pois é um importante produto de excreção dos organismos aquáticos e degradação da ração não consumida. Nestes filtros biológicos, os microorganismos responsáveis pelo tratamento da água residuária se encontram aderidos no meio de preenchimento, formando um biofilme. O presente trabalho teve como objetivo caracterizar as comunidades microbianas presentes no biofilme associado ao filtro biológico de uma unidade experimental de tratamento de efluente de aquacultura. Durante o experimento, realizado em dois sistemas paralelos representando unidades de aquacultura com e sem recirculação de água, também foram monitorados parâmetros de qualidade da água. Os tanques experimentais foram povoados com juvenis de tilápias-do-Nilo (Oreochromis niloticus), que foram submetidos a pesagens a cada quinze dias para avaliar seu ganho de biomassa. As bactérias foram identificadas através da técnica de análise microbiológica da hibridização fluorescente in situ (FISH). A estrutura do biofilme foi avaliada através de microscopia eletrônica de varredura. Os resultados indicam que a nitrificação teve um papel mais importante no controle da qualidade da água no sistema com recirculação em relação ao tanque sem recirculação. A análise microbiológica do meio de preenchimento do filtro revelou uma presença marcante (com proporções de Cy3/DAPI variando entre 0,5% e 7,6%) de células ativas de organismos nitrificantes (oxidadores de amônia e de nitrito), pertencendo a gêneros distintos como Nitrobacter, Nitrococcus e Nitrosomonas, além de outros grupos de presença expressiva, como bactérias filamentosas (com proporções de 11,2% a 17,3% da contagem de células marcadas com DAPI). As imagens de Microscopia Eletrônica de Varredura revelaram a natureza do arranjo destas bactérias no meio filtrante, caracterizando um biofilme bem desenvolvido, composto por diversos morfotipos microbianos. O conhecimento das bactérias que compõe este biofilme pode tornar possível a geração de melhorias que podem ser implementadas para aumentar a eficiência do sistema. / In recirculating aquaculture, biological filters are used for treating the effluent before it returns to tanks. These treatment units are intended for transforming ammoniacal nitrogen into nitrate, since ammonia and nitrite are toxic to fish. Ammoniacal nitrogen tends to accumulate in culture water, because it is an important excretion product from aquatic organisms and also due to degradation of non consumed feed. In these biological filters, microorganisms responsible for the treatment of waste water adhere to the filler, forming a biofilm. The present work intended to characterize the microbial community present in the biofilm associated to the biological filter at an experimental aquaculture effluent treatment unit. During the experiment, conducted in two parallel systems representing aquaculture units with and without water recirculation, water quality parameters were also monitored. Experimental tanks were populated with juvenile Nile Tilapias (Oreochromis niloticus), which were subjected to weighing every 15 days in order to assess their biomass gain. Bacteria were identified through the microbiological analysis technique of Fluorescent In Situ Hybridization (FISH). The biofilm structure was assessed using scanning electron microscopy. The results indicate that nitrification had a more important role in the control of water quality in the system with recirculation compared with the tank without recirculation. The microbiological analysis of the filter media revealed a significant presence (with Cy3/DAPI range between 0.5% e 7.6%) of active cells from nitrifying organisms (ammonia and nitrite oxidizers), which belonged to different genera such as Nitrobacter, Nitrococcus and Nitrosomonas, in addition to groups that had an expressive presence, such as filamentous bacteria (representing 11.2% to 17.3% of the total DAPI stained cells). Scanning Electron Microscopy images revealed the nature of the arrangement of these bacteria in the filtering media, characterizing a well developed biofilm made up of diverse microbial morphotypes. The knowledge about the bacteria making up the biofilm may enable improvements that can be implemented to increase system effectiveness.

Orientadores: Marco Aurelio Cremasco, Alexandre de Paula Peres / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-08T18:40:27Z (GMT). No. of bitstreams: 1 Betioli_MarioLuisPenteado_M.pdf: 23779149 bytes, checksum: 6c1ff800d2c4c61f6e72eab4a95e69f2 (MD5) Previous issue date: 2007 / Resumo: Este trabalho tem por objetivo apresentar a distribuição axial de pressão estática ao longo de um leito fíuidízado circulante (CFB) para diversos valores de velocidade de gás e fluxo mássico de sólidos; para tanto, avaliou-se a influência da concentração de sólidos presente em um escoamento gás-sólido ao longo de todo o CFB, o que possibilitou estudar, em um mesmo sistema, a fluidodinâmica dos reatores downer e riser, de uma seção que os une - uma curva em "U" - assim corno de um sistema de recirculação de sólidos. Os CFBs são utilizados em diversas indústrias, particularmente naquelas que envolvem processos de craqueamento catalítico em leito fluidizado (FCC). O FCC é um processo de refino de petróleo utilizado para aumentar a produção de gasolina e GLP (gás liquefeito de petróleo) de uma refinaria, por meio da conversão de frações pesadas, provenientes da destilação do petróleo (gasóleo e resíduos), em trações mais leves. Os experimentos foram conduzidos em uma planta piloto instalada no Laboratório de Processos em Meios Porosos (LPMP) da DTF/FEQ/UMCAMP, denominada Unidade Multipropósito de Craqueamento Catalítico. Realizaram-se ensaios utilizando vazões de ar iguais a 7,5m3/h, 10m3/h, 15 m3/h, 20 m3/h, 25 m3/h, 30 m3/h alimentadas: i) na entrada do downer; ii) na entrada da curva em "U"; iii) numa combinação da entrada do downer e da entrada da curva era "U". Os fluxos mássicos de sólidos utilizados para cada vazão de ar foram iguais a 0,000kg/m2s, 0,032kg/m2s, 0,076kg/m2s, 0,120kg/m2s, 0,164kg/m2s e 0,208kg/m2s alimentados na entrada do downer. Decorrente deste estudo experimental, além do perfil axial de pressão, foi avaliado um modelo simplificado para a descrição da fluidodinâmica em questão, cujos resultados obtidos para diferença de pressão foram comparados com aqueles obtidos de forma experimental, estes por meio de deflexão / Abstract: The aim of this work is to present the axial distribution of static pressure throughout a circulating fluidized bed (CFB) for diverse values of gas velocity and solids circulation rate; for this, it was evaluated the influence of the present solids concentration in a gas-solid flow throughout the entirety CFB, which made it possible to study, in the same system, the fluid-dynamics of the downer and riser reactors, of a section joining them --- a "IT bend - as well as of a solid recirculation system. The CFBs have been used in several industries, particularly m those involving processes of fluid catalytic cracking (FCC). The FCC is a refining process of petroleum used to increase the gasoline production and LPG {liquefied petroleum gas) of a refinery, by the conversion of weighed fractions, proceeding from petroleum distillation (gasoil and residues), in lighter fractions. The experiments have been led in a pilot plant installed in the Laboratory of Processes in Porous Media (LPMP) of the DTF/FEQ/UNICAMP, called Multipurpose Unit of Catalytic Cracking. Assays have been performed using air flow rates equal to 7,5m³/h, 10m³/h, 15 m³/h, 20 m³/h, 25 m³/h, 30 m³/h fed: i) in the entrance of the downer; ii) in the entrance of the "U" bend; iii) in a combination of the entrance of the downer and the entrance of the "U" bend. The solids circulation rates used for each air flow rate were equal to 0,000kg/m²s, 0,032 kg/m²s, 0.076 kg/m²s, 0,120 kg/m²s, 0,I64 kg/m²s and 0.2O8 kg/m²s fed in the entrance of the downer. Due to this experimental study, besides the pressure axial profile, a simplified pattern for the fluid-dynamics description in question was evaluated, whose results obtained for pressure difference were compared with those obtained through experiments, the latter being by the means of pressure gauge deflection / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

The development of communications technologies has led to an ever-increasing requirement for a wider bandwidth of microwave signal processing systems. To overcome the inherent electronic speed limitations, photonic techniques have been developed for the processing of ultra-broadband microwave signals. A dispersive delay line (DDL) is able to introduce different time delays to different spectral components, which are used to implement signal processing functions, such as time reversal, time delay, dispersion compensation, Fourier transformation and pulse compression. An electrical DDL is usually implemented based on a surface acoustic wave (SAW) device or a synthesized C-sections microwave transmission line, with a bandwidth limited to a few GHz. However, an optical DDL can have a much wider bandwidth up to several THz. Hence, an optical DDL can be used for the processing of an ultra-broadband microwave signal. In this thesis, we will focus on using a DDL based on a linearly chirped fiber Bragg grating (LCFBG) for the processing of broadband microwave signals. Several signal processing functions are investigated in this thesis. 1) A broadband and precise microwave time reversal system using an LCFBG-based DDL is investigated. By working in conjunction with a polarization beam splitter, a wideband microwave waveform modulated on an optical pulse can be temporally reversed after the optical pulse is reflected by the LCFBG for three times thanks to the opposite dispersion coefficient of the LCFBG when the optical pulse is reflected from the opposite ends. A theoretical bandwidth as large as 273 GHz can be achieved for the time reversal. 2) Based on the microwave time reversal using an LCFBG-based DDL, a microwave photonic matched filter is implemented for simultaneously generating and compressing an arbitrary microwave waveform. A temporal convolution system for the calculation of real time convolution of two wideband microwave signals is demonstrated for the first time. 3) The dispersion of an LCFBG is determined by its physical length. To have a large dispersion coefficient while maintaining a short physical length, we can use an optical recirculating loop incorporating an LCFBG. By allowing a microwave waveform to travel in the recirculating loop multiple times, the microwave waveform will be dispersed by the LCFBG multiple times, and the equivalent dispersion will be multiple times as large as that of a single LCFBG. Based on this concept, a time-stretch microwave sampling system with a record stretching factor of 32 is developed. Thanks to the ultra-large dispersion, the system can be used for single-shot sampling of a signal with a bandwidth up to a THz. The study in using the recirculating loop for the stretching of a microwave waveform with a large stretching factor is also performed. 4) Based on the dispersive loop with an extremely large dispersion, a photonic microwave arbitrary waveform generation system is demonstrated with an increased the time-bandwidth product (TBWP). The dispersive loop is also used to achieve tunable time delays by controlling the number of round trips for the implementation of a photonic true time delay beamforming system.

Pressurized chemical looping combustion (PCLC) is a promising next generation carbon capture technology which operates on the fundamentals of oxyfuel combustion to concentrate carbon dioxide in the flue gas stream. Oxygen is supplied through cyclic oxidation and reduction of a solid metal oxide between an air reactor and fuel reactor to prevent the direct contact of fuel and air. CanmetENERGY-Ottawa, in collaboration with Hatch Ltd., is designing a pilot scale PCLC system which uses ilmenite as the oxygen carrier and a novel fluidized bed design called the Plug Flow Internally-recirculating Reactor (PFIR). The PFIR consists of an annular bubbling fluidized region in which particles are circulated by angle jets through two reactive zones separated by baffles. The overall objective of this thesis was to provide key design parameters and insight for the construction of the pilot facility. Experimental work was first conducted investigating the minimum fluidization velocity (Umf), gas bubble size, and tube-to-bed heat transfer coefficients of different ilmenite particle size distributions (PSDs) at varying pressures up to 2000 kPa. The data was compared to a variety of literature correlations. The Saxena & Vogel (1977) constants for the Wen-Yu type correlations (Remf=√C12+C2Ar-C1) resulted in the best fit for predicting the Umf of the PSDs with Sauter mean diameters (SMD) less than 109 μm, while the Chitester et al. (1984) constants resulted in better predictions for the larger particle size distributions (SMD greater than 236 μm). Gas bubble size was found to be marginally impacted by pressure, with the Mori & Wen (1975) correlation best fitting the data. The heat transfer coefficient was found to also be marginally increased by pressure with the the Molerus et al. (1995) correlation matching the atmospheric data. A computational particle fluid dynamic (CPFD) model of the experimental unit was then created and validated using the obtained data for minimum fluidization velocity and bubble size. The accuracy of the model was found to be dependent on the particle close packing factor input variable, with a value of 0.58 resulting in the best results for each of the ilmenite PSDs modeled. Finally, a CPFD model was created for a cold flow design of the PFIR to investigate the impacts of different operating parameters on the solids circulation rate and gas infiltration rate between the two reactor zones. This model used the validated parameters of the previous CPFD model to add confidence to the results. The impacts of increasing superficial gas velocity, fluidizing gas jet velocity, bed height, and pressure were all found to increase the solids circulation rate through their respective impacts on the momentum rate of the fluidizing gas. A polynomial function was fit between these two variables resulting in a method to predict the solids circulation rate. Similarly, the rate of gas infiltration between sections was found to be dependent on the solids circulation rate, allowing for a function to be made to predict the gas infiltration at different operating conditions.

Propagation and culture has been accepted as an approved aquaculture method for resource managers to enhance and recover freshwater mussel populations. Although juveniles can be produced readily for many mussel species, achieving high growth and survival in the laboratory remains difficult. The goal of my project was to improve growth and survival of juvenile mussels by comparing diets, algae concentration, and culture systems. The first objective determined a suitable diet for feeding juvenile northern riffleshell, Epioblasma torulosa rangiana, a species listed as federally endangered. Three algal diets were evaluated to determine differences in growth and survival of juveniles of E. t. rangiana. After 60 d, mean survival on Phytofeast, Shellfish Diet, and WSSNFH mix were 75.1 (95% CI: 72.2 to 78.0), 78.9 (95% CI: 74.5 to 83.2), and 85.0 (95% CI: 80.6 to 89.3) percent, respectively. WSSNFH mix had the highest survival which was significantly different from Phytofeast (p=0.01).  Mean shell lengths were 2.37 mm (95% CI: 2.27 to 2.47), 2.62 mm (95% CI: 2.52 to 2.72), and 3.11 mm (95% CI: 3.01 to 3.22), respectively.  Juvenile length on all three diet treatments was significantly different from each other (p<0.0001), with the WSSNFH mix exhibiting the highest growth, and Phytofeast with the lowest growth. My second objective evaluated the effect of algal concentration (cells mL-1) on growth and survival of juveniles of E. t. rangiana and mucket, Actinonaias  ligamentina. After 60 d, mean survival of E. t. rangiana for the low (30,000 cells mL-1), medium (80,000 cells mL-1), and high (140,000 cells mL⁻¹) algal concentrations were 39.1 (95% CI: 30.7 to 47.4), 20.7 (95% CI: 12.8 to 28.6), and 12.7 (95% CI: 4.82 to 20.5) percent, respectively (p<0.01). Mean shell lengths were 1.58 mm (95% CI: 1.49 to 1.66), 1.30 mm (95% CI: 1.19 to 1.40), and 1.01 mm (95% CI: 0.936 to 1.08), respectively (p<0.0001).  Mean survival of A. ligamentina for the low, medium, and high algae concentrations were 46.8 (95% CI: 35.2 to 58.4), 24.6 (95% CI: 15.1 to 34.0), and 10.7 (95% CI: 5.45 to 15.9) percent, respectively (p<0.01). Significant differences were observed between the low feed concentration versus the medium and high feed concentrations. Mean shell lengths for the low, medium, and high concentrations were 1.15 mm (95% CI: 1.08 to 1.22), 0.994 mm (95% CI: 0.930 to 1.06), and 0.833 mm (95% CI: 0.770 to 0.896), respectively. All concentrations were significantly different, and the low concentration had the highest mean shell length (p<0.0001). The third objective compared the performance of three recirculating aquaculture systems for rearing juvenile mussels >5 mm. Mean incremental length of juveniles of E. t. rangiana at 60 d in Pans, Buckets, and Upwellers was 1.19 mm (95% CI: 0.746 to 1.62), 1.05 mm (95% CI: 0.608 to 1.49), and 2.07 mm (95% CI: 1.63 to 2.51), respectively. Incremental lengths were significantly higher in the Upwellers (p=0.03). The mean lengths for Bucket and Pan systems were not significantly different from each other (p=0.54).  Percent survival of juveniles for the Pans, Buckets, and Upwellers were 91.7 (95% CI: 87.4 to 96.0), 90.0 (95% CI: 80.6 to 99.4), and 100 (95% CI: 100 to 100), respectively. Survival in the Upwellers was significantly higher than in the Buckets (p=0.018). Survival of juveniles in the Pan system and Upwellers were not significantly different from each other (p=0.05).  Mean growth for A. ligamentina was 1.96 mm (95% CI: 1.03 to 2.9), 0.88 mm (95% CI: 0.048 to 1.80), and 2.46 mm (95% CI: 1.537 to 3.38), respectively (p=0.07). Mean percent survival of juveniles of Actinonaias ligamentina in the Pans, Buckets, and Upwellers were 100 (95% CI: 100 to 100), 86.7 (95% CI: 74.0 to 99.4), and 100 (95% CI: 100 to 100), respectively.   Survival of A. ligamentina in the Upwellers was significantly higher than in Buckets (p<0.0001).  Juvenile survival in the Pan system and Upwellers was not significantly different (p=0.998). Results indicate that the Upweller culture system supported the highest growth and survival in culturing E. t. rangiana and A. ligamentina. / Master of Science

No description available.

As the importance of water use in the power generation sector increases across the nation, the ability to obtain and analyze real power plant data is pivotal in understanding the water energy nexus. The Navajo Generating Station in Arizona and the Browns Ferry Nuclear Plant in Alabama are examples of where water shortages have threatened the operation of power generators. The availability of freshwater in the United States is beginning to dictate how and where new power plants are constructed. The purpose of this study is to provide and analyze cooling system parameters using 2008 data provided by the Energy Information Administration. Additionally, the cost of water saved among different categories of power plants is calculated. In general, the conditions which cause cooling systems to withdraw less water are not necessarily the more expensive conditions, and vice versa. While not all the variability in the cost of cooling systems is being accounted for, the results from this study prove that nameplate capacity, capacity factor, age of power plant, and region affect the costs of installed cooling systems. This study also indicates that it would be most cost effective for once-through cooling systems to be replaced with recirculating- pond instead of recirculating- tower systems. The implications of this study are that as power plant owner's struggle in balancing cost with water dependence, several parameters must first be considered in the decision-making process. / Master of Science

Recirculating aquaculture offers a prospect for successful fish farming, but this form of aquaculture presents a great potential for pathogenic microorganisms to become established in the system through the formation of biofilms. Biofilms are capable of forming on all aquaculture system components, incorporating the various microflora present in the water. Pathogenic microorganisms released from the biofilms are capable of causing recurring exposure to disease in both fish and humans. With the increased consumption of raw and rare fish, the presence of these bacteria in or on the fish could lead to ingestion of pathogens. There is also the possibility of cross-contamination during processing. The objectives of this study were to increase the understanding of pathogen incorporation into biofilms in recirculating aquaculture systems and to determine the effectiveness of various sanitizers in eliminating biofilms. Seven freshwater and two saltwater facilities were sampled, with eight different types of materials tested. Pathogenic bacteria were identified using Bacteriological Analytical Manual methods and rapid commercial test kits. Most of the pathogenic bacteria identified were opportunistic organisms ubiquitous in an aquatic environment. The most significant human pathogens were Bacillus cereus, the Shigella species and the Vibrio species. The major piscine pathogens of concern were Photobacterium damsela, the Vibrio species, and Aeromonas hydrophila. The most significant variation in biofilm pathogens was observed between facilities and not construction material. Buna-N rubber, polyvinyl chloride (PVC), chlorinated PVC, glass, fiberglass and stainless steel disks were suspended in 79.2 liter (20 gallon) aquariums stocked with Nile tilapia (Oreochromus niloticus). The tanks were inoculated with a known amount of green fluorescent protein (GFP) modified Escherichia coli and samples were removed on days 1,3, 7 and 15. The modified E. coli were isolated on Luria Broth Agar and plate counts were performed under ultraviolet light. There was no significant difference in the growth of the surrogate pathogen on the different materials. The GFP E. coli was isolated in the largest numbers 24 hours after inoculation of the tanks, with an approximate 1-log decrease after day 1. Days 3, 7, and 15 showed equivalent growth of the target organism. Two sets of disks were suspended in another six 79.2 liter (20 gallon) aquariums. The tanks were inoculated with a known amount of the surrogate pathogen, GFP E. coli, and after 24 hours one set of disks was removed from each tank. The second set of disks was removed and treated by spraying with water, alkaline cleanser, sodium hypochlorite, quaternary ammonium compound, or peracetic acid. Ozone was bubbled directly into one tank to treat another set of disks. The modified E. coli were isolated and counted. Total aerobic plate counts and Enterobacteriaceae counts were performed. Statistical analysis indicated that the type of material had no significant affect on the effectiveness of the sanitizers. It was determined that sodium hypochlorite (99.4591 overall reduction) and peracetic acid (98.8461 % overall reduction) were the most effective sanitizers overall, and ozone (32.9332 % overall reduction) was the least effective. / Ph. D.

Sustainable tilapia production at Blue Ridge Aquaculture (BRA) is constrained by availability of high quality replacement water. I developed a pilot-scale wastewater treatment system to treat and reuse effluent presently discharged. An initial study was conducted to determine the response of the BRA waste stream to ozone application. Dosages of 6.9, 4.8 and 2.4 g O3 were applied for 30 minutes to 35 L of settled effluent. Optimum ozone dosage and reaction time, ozone transfer efficiency, ozone yield coefficient, degree of pollutant removal, and other ozone and water quality parameters were determined. Most results suggested that the maximum process feasibility limit for ozone contact time was approximately 9 minutes at an applied ozone concentration of 23g/m3 (6.9 g O3 dose). Formation of foam increased solids and COD removal up to three times. Poor removal or accumulation of DOC and TAN was observed, indicating the need for biological treatment following ozonation. Next, I evaluated a pilot station treatment train including sedimentation, microscreen filtration, fluidized bed denitrification, ozonation, aerobic biological oxidation in a trickling filter, and jar-test chemical flocculation. Significant improvements were found regarding solids, COD, cBOD5, NO3--N, TKN, and turbidity. Removal of foam after ozonation improved ozonation efficacy and pollutant removal. A nitrogen budget for the BRA facility was derived, indicating that 35% of the nitrogen applied in feed was assimilated in fish. I evaluated the possible impact of residual inorganic nitrogen forms from treated effluent upon fish in the recirculating systems. I found that less than 1% of the TAN produced would return the recovered stream, and that the existing biological contactors can remove it. Evaluation of TAN fate indicated that 84% was oxidized in biofilters, 14% was oxidized by passive nitrification, and 1% was removed by water exchange. For NO3-N, I determined that 56% was removed by passive denitrification and 44% by daily water exchange. The pilot station design was effective for removing organics and nutrients, and can serve as the basis for scale-up for treating and reusing the entire BRA effluent stream. / Ph. D.

Aquacultured products assist the human demands for seafood so that foodfish supplies can remain sustainable and consistent. Although the fish-farming industry has seen dramatic growth and intensification in recent years, the latter has led to an increase in bacterial diseases and fish health management problems, resulting in major economic losses around the world. In addition to the lack of understanding of fish physiology, these complications are exacerbated by the inappropriate and controversial use of antibiotics. This work addressed these issues in striped catfish (Pangasius hypophthalmus) and Nile tilapia (Oreochromis niloticus), two economically important foodfish, by investigating alternative, more cost-effective options to promote fish health. The first two studies established reference intervals for immunology, hematology and plasma chemistry analytes in striped catfish in a recirculating aquaculture system (RAS). In a third study, the immunomodulatory effects after directly feeding probiotic strains of Bacillus subtilis NZ86 and O14VRQ in Nile tilapia were ascertained. This last study revealed that supplementation with both of the probiotic strains for 51 days stimulated several local and systemic innate immune responses of tilapia. When these transient probiotic bacteria were present in the gut, a pro-inflammatory environment was developed as evidenced by the localized higher expression of the cytokines tumor necrosis factor (TNF) – α and interleukin (IL) – 1β. Significant increases (p < 0.05) were noted differentially by both probiotic strains throughout the trial in plasma lysozyme content, alternative complement activity, and in the peripheral blood leukocyte profiles. Additionally, there were trends for increased levels of phagocytosis and respiratory burst in leukocytes of the anterior kidney and spleen at the end of the trial, suggesting the potential use of these probiotic strains for improved immune-competence. These findings help to understand and clarify the potential mechanism of action associated with the increased disease resistance recorded in preliminary studies with the same probiotic strains. Implementation of the tools established and validated in this work could be useful in evaluating fish welfare situations involving striped catfish grown in RAS conditions, and also show promise for a healthier foodfish supply where antibiotic applications practices could be minimized. / Ph. D.