Despite being a low fat fish and consequently a low omega-3 fish, tilapia have widespread consumer acceptability due to its mild taste, cheap price and low mercury content. However some sources claim that farmed tilapia can be detrimental to human health due to high omega-6:3 ratios and low omega-3 content specifically eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid. The objective of this study was to create an omega-3 enriching feed that would increase omega-3 content in tilapia and subsequently decrease the omega-6:3 ratio. An 8 week feeding trial was conducted. Tilapia were cultured in a recirculating aquaculture system on one of eight diets (control, commercial, 1, 3, 5% fish oil or 1.75, 5.26, 8.77% ALL-G-Rich (algae). Water quality, selected fish biometrics and growth performance were recorded. Fillet and rib meat tissues were collected at weeks 4 and 8, and liver and mesenteric fat tissues were collected at week 8. Fat was extracted, trans-methylated and identified as fatty acid methyl esters using gas chromatography-mass spectrometry. Docosahexaenoic acid increased in concentration in all tissues as percent fish oil and ALL-G-Rich increased in the diets with 8.77% ALL-G-Rich resulting in significantly (P<0.0001) greater concentrations in the fillet and mesenteric fat compared to all other diets after 8 weeks. The 8.77% ALL-G-Rich diet resulted in significantly (P=0.003) greater cumulative accumulation of EPA, DPA and DHA on a mg/4oz fillet basis after 4 weeks compared to control. The results of this study suggest that an ALL-G-Rich finishing feed could be produced that would result in a value added farmed tilapia fillet. / Master of Science in Life Sciences

Thesis--Auburn University, 2009. / Abstract. Includes bibliographical references (p. 40-43).

With World Health Organization estimation of population increase to over 9 billion by 2050, malnutrition and food insecurity are predicated to be two of the main challenges facing the world in the future. Fish is a source of protein that can have a significant contribution for solving the global food crisis. Fish for human consumption is provided by both the aquaculture industry and the capture fisheries, however, the flat-lined production of seafood from capture fisheries means aquaculture production should double in number to provide enough protein by 2050. Culturing fish at higher densities is being used as a way to increase the global aquaculture production. Modern aquaculture intensified practices expose the fish to various stressors that can negatively impact their welfare. Good nutrition can improve the health status of aquacultured fish while accumulation of specific nutrient can add value to the fillet. In line with that, the studies described in this dissertation aimed to examine the vital role of fish in human health and evaluate strategies to improve the sustainable aquaculture production of fish using novel aquafeeds. This was completed by conducting a survey of the essential minerals and heavy metals of commercially available catfish, salmon, and tilapia fillets in the United States marketplace and three fish nutritional trials to evaluate the impacts of novel aquafeeds on production and health of fish and the food quality of their respective fillets. Selenium with the established health benefit for human and fish was the trace mineral of interest in this dissertation. This element is the main component of a group of selenium containing proteins called selenoproteins that are antioxidant and maintain oxidative homeostasis of fish and human. Additionally, selenium is an antagonist for many heavy metals such as mercury. The market study revealed that catfish, salmon and tilapia samples available in United States marketplace are good source of selenium, zinc and phosphorous. The concentration of heavy metals in all the samples were lower than safety standards. Nile tilapia (Oreochromis niloticus) and rainbow trout (Oncorhynchus mykiss), which are two economically important aquacultured fish, were used as animal models in the fish nutritional trials. Different forms of selenium supplemented to Nile tilapia diet. The form of Dietary Se form did not have any significant (p>0.05) effect on growth, and plasma and hepatic GPX activity of Nile tilapia. However, organic selenium supplement showed significantly (p<0.05) higher bioavailability and accumulated in the fillets at the significantly higher concentration. In the second fish trial selenoneine, a novel selenium containing compound, was supplemented at various concentrations to rainbow trout diet. Other than growth parameters multiple other health biomarkers (lysozyme, glutathione peroxidase, superoxide dismutase activities) were examined to determine whether selenoneine supplementation had a positive impact on fish health. Selenoneine enriched diet significantly(p<0.05) increased the weight gain, lysozyme and oxidative enzymes activities of rainbow trout. Lastly rainbow trout feed was supplemented with commercially available probiotic (Actisaf®), prebiotic (Safmmann®), and their mixture (synbiotic). These dietary supplements did not have any significant effect on fish production but led to a significant increase in activity of oxidative enzymes in plasma when compared to control diet. These results suggest that feed supplements used in this dissertation can be used to promote the fish health raised in recirculating aquaculture systems and support an economically and environmentally sustainable aquaculture. / PHD / Fish contributes significantly to human’s diet in terms of high quality, easily digestible animal protein that helps fight malnutrition and food insecurity. More than half of the fish for human consumption is produced by the aquaculture industry and the growth of the industry is very critical for meeting the future needs for protein. Other than production of high-quality protein the aquaculture industry has made a great contribution to people’s livelihood, poverty alleviation, income generation, employment and, trade globally. To continue contributing effectively to global food security aquaculture industry should overcome various obstacles such as disease and sustainable production of high-quality feed. In this dissertation, important roles of fish in human diet was examined by measuring the mineral composition of commercially available catfish, salmon and tilapia in the United States market place. Also diets of Nile tilapia and rainbow trout were supplemented with various forms of selenium, prebiotics, and/or probiotics which have positive effect on health of both human and fish. These supplementations led to production of valued-added fish fillets enriched in selenium and improved the fish growth and health.

The purpose of this study is to modify an existing static analytical model developed for a Re-circulating Aquaculture Systems through incorporation of risk considerations to evaluate the economic viability of the system. In addition the objective of this analysis is to provide a well documented risk based analytical system so that individuals (investors/lenders) can use it to tailor the analysis to their own investment decisions—that is to collect the input data, run the model, and interpret the results. The Aquaculture Economic Cost Model (AECM) was developed by Dr. Charles Coale, Jr. and others from the department of Agricultural and Applied Economics at Virginia Tech. The AECM is a spreadsheet model that was developed to help re-circulating aquaculture producers make strategic business decisions. The model can be used by potential producers interested in investing in re-circulating aquaculture through development of a financial analysis that in turn will help them obtain funding for the enterprise. The model is also useful for current producers who want to isolate inefficient aspects of their operation. AECM model consists of three major sections which include the Data Entry, Calculations and Analysis. The first section requires that the producer conducts background research about their operation to ensure accurate calculation and analysis. The calculation section provides a great deal of information about the operation's finances, while the analysis section provides information about the operation's financial stability. While the AECM is a powerful model, it is based on single, usually mean, values for prices, costs, and input and output quantities. However, market, financial and production uncertainties result in fluctuating prices, costs and yields. An individual who is making management decisions for a re-circulating aquaculture system will be faced with some or all of these uncertainties. By adding simulation to the AECM model to account for these uncertainties individuals will be able to make better management decisions. Information of the varying likelihoods or probabilities of achieving profits will be of crucial interest to individuals who plan on entering into or modifying an existing aquaculture system. Risks associated with six variables were examined in this paper: feed cost, feed conversion, mortality rate, capital interest rate, final weight, and output price. Data for the Interest Rate and output price were obtained from the Federal Reserve System and NMFS website respectively. Expert opinion was the source of data for the other variables. After probability distributions were applied to the random variables to account for the uncertainty the model was simulated for ten thousand iterations to obtain expected returns for three years in advance that the model calculates an income statement. In addition to that, sensitivity analyses were carried out in order to inform the producer which factors are contributing the most to the profitability of the operation. In this way the producer will have a better idea as to which aspects of the operation to monitor closely and consider modifying. The analysis shows that the mean income for the three years will be negative and thus the business would be losing money. The simulated mean net incomes were: -$216,905, -$53,689, -$53,111 for year1 through year3 respectively. Sensitivity analysis confirmed that output price is by far the most significant input that makes the overall bottom line to fluctuate most. Output price was on top of the list for all the three years analyzed in this study. Feed cost and Feed conversion were the next most significant inputs. The other inputs were also significant in explaining the fluctuation of the bottom line; however both their regression and correlation coefficients were small. / Master of Science

Orientador: Tsunao Matsumoto / Banca: Alexandre Ninhaus Silveira / Banca: Katt Reginal Lapa / Resumo: Sistemas de Recirculação para Aquicultura (SRA) possibilitam um meio alternativo de produção de peixes para áreas com limitada disponibilidade de água. Estes sistemas de cultivo intensivo de peixes oferecem potencial de produção em pequena escala assim como em grande escala, devido a recuperação de efluentes e a reutilização da água, produzindo volumes relativamente pequenos de resíduos líquidos e sólidos. O objetivo deste estudo foi determinar a eficácia do tratamento de águas residuárias em relação à remoção de Nitrogênio Amoniacal Total (NAT), Sólidos Totais (ST), Sólidos Suspensos Totais (SST), Demanda Química de Oxigênio (DQO) e Demanda Bioquímica de Oxigênio (DBO5), Nitrogênio total (NT) e Fósforo Total (FT). Para tanto, foram introduzidos Tilápia do Nilo (Oreochromis niloticus), com 0,323kg de peso médio inicial e 17 kg m-3 de densidade de armazenamento inicial no SRA experimental. O SRA era composto de 03 tanques de plástico com capacidade de 0,20 m3, Decantador de Coluna (DC), o reator de leito fluidizado aeróbio com circulação em tubos concêntricos (BAS-CT), tendo como meio de suporte a areia de diâmetro efetivo (D10) = 0,29 mm e na sequência reator de transferência de oxigênio e remoção de CO2. A eficiência na remoção do NAT no reator BAS-CT no período de aclimatação e de estabilização foi 31,0% e 35,2%, respectivamente. A remoção de ST e SST foi de 44,44% e 71,71%, respectivamente. A eficiência alcançada de remoção no SRA da DQO foi de 64,90% e de 48,01% para DBO5. Os valores médios de remoção do NT e FT no SRA foram de 25,02% e 41,05%, respectivamente. Estes resultados indicaram que o tratamento de águas residuárias de aquicultura proposto neste estudo através do BAS-CT associado ao DC tem evitado elevadas concentrações e acumulação de poluentes dentro do SRA / Abstract: Recirculating aquaculture systems (RAS) offer an alternative means of fish production for areas that to have limited water and land availability. RAS are a highly intensive fish culture systems and offer potential production units for small and large scale operations. For effluent recovery and treated water reuse, RAS produce relatively small volumes of liquid and solids wastes. The objective of this study were to determine the efficiency of the wastewater treatment with recommended to removal of Total Ammonia Nitrogen (TAN), Total Solids (TS), Total Suspended Solids (TSS), Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD5), Total Nitrogen (TN) and Total Phosphorus (TP). In this study was cultivating the Nile Tilapia (Oreochromis niloticus) with 0.323kg initial average weight and 17 kg m-3 initial storage density, cultivated in RAS. The RAS was composed with 03 plastic tanks with capacity of 0.20 m3 in each, column settler (CS), aerobic fluidized bed reactor with concentric tubes circulation (BAS-CT) with sand bed support of effective diameter (D10) of 0.29 mm and oxygen transfer-CO2 removal reactor. NAT removal efficiency was in acclimation and stabilized periods in BAS-CT reactor were 31.0% and 35.2% respectively. TS and TSS removal was 44.44% and 71.71% respectively. In this RAS, the COD removal efficiency reached was 64.90% and 48.01% for BOD5. The average removal in the NT and FT in the RAS were 25.02% and 41.05% respectively. These results indicate that aquaculture wastewater treatment proposed in this study by BAS-CT associated to CS prevents high concentrations and accumulating of pollutants within the SRA

Integrated aquaculture systems (IAS) are a type of recirculating aquaculture systems (RAS) where the wastewater is treated and returned to the fish tanks. The important difference between the two is that in an IAS, wastes from the aquaculture component are recovered as fertilizer to produce an agricultural product whereas in an RAS, waste organics, nutrients and solids are treated and discharged. A pilot marine IAS at Mote Aquaculture Research Park in Sarasota, FL was studied for this project. Water quality monitoring, measurements of fish health and growth rates of fish and plants were performed over a two-year period to determine the effectiveness of the system in producing fish and plant products and removing pollutants. The goal of this portion of the project was to develop, calibrate and evaluate a model of the system, to understand the nitrogen transformations within the Mote IAS and to investigate other potential configurations of the Mote IAS. The model was divided into the various compartments to simulate each stage of the system, which included fish tanks, a drum filter for solids removal, and moving bed bioreactor (MBBR) for nitrification and disinfection. A solids tank after the drum filter was used to store the drum filter effluent slurry, which was then divided between three treatment processes: a geotube, a sand filter followed by a plant bed, and a plant bed alone. Nitrogen species modeled were particulate organic nitrogen (PON), dissolved organic nitrogen (DON), ammonium and nitrate. Of the physical components of the IAS, models of the MBBR and the two plant raceways included physical, chemical and biological nitrogen transformation processes. The sand filter, solids tank and geotube models were simple mass balances, incorporating factional removals of each species based on the observed data. Other variables modeled included temperature, dissolved oxygen, volatile suspended solids and chemical oxygen demand concentrations. The model was built in a computer program, STELLATM, to simulate the Mote IAS. The model calibration involved experimental, literature and calibrated parameters. Parameters were adjusted until the model's output was a best fit to the observed data by minimizing the sum of the squared residuals. During the sensitivity analysis, two model parameters caused large variations in the model output. The denitrifier constant caused the most variation to the model's output followed by the denitrifier fraction of volatile suspended solids. Of the removal processes, denitrification was the largest nitrogen removal mechanism from the model, accounting for 59% and 55% of the nitrogen removed from the south and north plant raceways respectively. Plant and soil uptake represented only 0.2% of the overall nitrogen removal processes followed by 0.1% by sedimentation. Finally, the model was used to investigate other treatment designs if the Mote IAS was redesigned. The first option involved a geotube and one plant raceway in series to treat the solid waste while the second option did not have a geotube, but two plant raceways. The first option was the most effective at removing nitrogen while the second was as effective as the original system and would cost less.

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.

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.

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.

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