South Africa is one of the countries with the largest mining operations in the world. Most of these mines make use of natural dams and rivers in their water supply, which often are being pumped back into the natural environment. The reticulated water pumped back into the system may contain high concentrations of dissolved chemicals, which may lead to the reduction of the endemic organisms. Many of the heavy metals mined in South Africa are highly toxic at very low concentrations, and it is therefore very important to do frequent analysis on the aquatic environment. The value of chemical analysis per se has become limiting, as chemical analysis supplies information on the levels of chemicals at a certain time, and the new trend is to incorporate biological monitoring into existing monitoring strategies. Heat shock proteins are classified as stress proteins and are primarily expressed under stressful conditions, therefore having the potential to be used as possible biomarkers. Cortisol, also a known stress hormone, has been suspected of suppressing the expression of heat shock proteins by replacing the heat shock protein on the glucocorticoid receptor. This leads to reduced levels of heat shock proteins in the organism through a negative feedback mechanism. However, before information on heat shock proteins and cortisol can be successfully incorporated into ecological risk assessment, an understanding of how cortisol influences heat shock protein levels after heavy metal exposure is needed. This study aims to determine what effect cortisol had on the production of a specific member of the Hsp70 class of heat shock proteins at different time intervals after exposure of Oreochromis mossambicus to various metals. Proteins were determination using the Bradford method, while protein separation was done using Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis. Thereafter, separated proteins were subjected to Western blotting and immunoblotting in order to quantify the different Hsp70 family members in the hepatic tissue. Cortisol levels were determined using a commercially available Cortisol ELISA Test Kit. Hsp70 accumulation occurred in only two exposure groups, namely the cadmium and chromium exposure groups. Accumulation of Hsp70 demonstrated an increase in accumulation rates at the 24 hour time interval of the 10% cadmium exposure group, with accumulation remaining relatively constant in the 20% cadmium exposure group. Accumulation of Hsp70 occurred only at the 48 and 96 hour time intervals in the 10% chromium exposure group. The accumulation of Hsp76 and Hsp74 were observed to follow the same pattern throughout the 96 hour exposure. In the 10% exposure groups accumulation of both Hsp76 and Hsp74 indicated an increase in accumulation rates at the 72 hour of groups exposed to chromium and nickel, whereas the accumulation of Hsp76 and Hsp74 remains constant after exposure to cadmium. In the 20% cadmium exposure group, an increase in Hsp76 and Hsp74 accumulation was observed at the 24 hour time interval, whereby accumulation of Hsp76 and Hsp74 remains constant in both the chromium and nickel 20% exposure groups. Males accumulated higher levels of Hsp70 members than females in the cadmium and chromium exposure groups. In the 10% exposure groups the females accumulated higher levels of Hsp74, whereas the males accumulated higher levels of Hsp74 in the 20% exposure groups. Accumulation of Hsp76 proved to be higher in the females in all exposure groups, compared to the males. Cortisol concentrations remained constant throughout the 96 hour exposure period, with higher cortisol levels observed in the chromium exposure groups. Cortisol concentrations proved to increase at higher concentrations of metal exposure. Cortisol proved to have no significant effect on Hsp70 family member accumulation, except in the cadmium exposure group, where a negative regression was observed. Accumulation of the HSp70 member can be linked to possible metal specificity, due to the fact that Hsp70 accumulated in only two metal species (cadmium and chromium). However, the accumulation of Hsp76 and Hsp74 may possibly prove that the higher concentrations of specific metals leads to early accumulation of heat shock proteins. The higher accumulation levels of Hsp70 in males, compared to accumulation levels in females may be due to the greater need to discard damadged or denatured proteins, whereas higher Hsp74 and Hp76 accumulation levels in females, may be due to the higher levels of reproductive proteins present in females, compared to males. This study therefore concluded that cortisol may have no significant effect on the accumulation of the Hsp70 family members in the liver of fish. / Prof. J.H.J. Van Vuren

M.Sc. / Developments in the catchment area of the Olifants River, such as poor agricultural practices and overgrazing, caused increased amounts of erosion material to enter the river. This leads to the silting up of the Phalaborwa Barrage, situated in the river, on the border of the Kruger National Park. Because of the occasional flushing of the Barrage, in order to retain storage capacity, the Olifants River inside the Kruger National Park is subjected to very high sediment loads. This has led to poor water quality and subsequent fish mortalities. The objective of this study was therefore to investigate the possible effects of silt loads released from the Barrage on the survival of selected life stages of Oreochromis mossambicus. Silt was collected from the Phalaborwa Barrage, and the silt/fish interaction was invesigated under controlled laboratory conditions. Oreochromis mossambicus was exposed to various silt concentrations for different exposure periods to determine the LC50 and sub-lethal concentration ranges. After determination of sub-lethal values, 0. mossambicus was exposed to these concentrations to determine whether they have any effects on the oxygen consumption and selected haematological parameters of exposed fish. Lethal levels for suspended sediment are interrelated with age differences of the fish, particle size of the suspended sediment and concentration. Increased suspended sediment disrupted activity and respiratory patterns, changed orientation responses and ultimately resulted in the death of the fish. The gills and the opercular cavities of the dead fish were usually clogged with a thick layer of mucus and silt. The laboratory experiments revealed that LC5 0 values for 0. mossambicus ranged from 26,78 to 54,20g silt/1 for larvae, 35,10 to 39,20g silt/1 for juveniles and 32,93 to 35,43g silt/1 for adult fish. The larval stage was generally less tolerant of suspended silt than juveniles and adults. Sub-lethal levels for adult fish ranged from 0 to 27g silt/l, where no mortalities occurred. Exposure of adult fish to sub-lethal concentrations of silt did alter routine oxygen consumption by causing increased rates (9 to 330% from initial) of oxygen consumption. This indicates that sub-lethal levels of suspended silt concentrations result in an increase in oxygen consumption by the fish due to an increase in metabolic rate associated with increased activity and stress. Silt exposure Exposure of adult fish to sub-lethal silt concentrations (<20g silt/l) resulted in increases in haemotocrit, red blood cell counts, white blood cell counts and blood glucose concentrations, but decreases in haemoglobin and mean corpuscular volume when compared to that for the control fish. These differences became more apparent as the silt exposure concentration increased with statistically significant differences (P<0.05) between most of the selected

Contamination of aquatic ecosystems (for example, dams, lakes, rivers, streams) with heavy metals (according to McDonald and Wood (1993), the metals that are of greatest concern in fresh waters are Hg, Pb, Cd, Cu, Zn, AI, Mn and Cr (approximately in order of decreasing toxicity)) has been receiving increased worldwide attention, and the literature has many publications on the topic. These amplified levels of contamination have become a global problem in both developed and developing countries and the impact of them on aquatic environments is severe due to the inability of water to disperse contaminants. To meet this threat, ecotoxicologists face a difficult challenge on how to assess the long-term impacts of metals which have already been released into the environment and which persist in sediment, water and biota. In recent years, the field of biomarker study has evolved and expanded rapidly to address this void. Biomarkers examine molecular and biochemical responses in exposed individuals in an effort to assess the status of an impacted environment and they can also serve as a basis for a Rapid Risk Assessment of Fish Health (RRAFH) employed by water quality managers. This effort to incorporate biomarkers into RRAFH research will eventually be worthwhile. Moreover, with this multidisciplinary approach, cause-effect relationships may be examined. It was in this context that the present study evaluated three biomarkers (metallothionein (MT), Na+K+ ATPase and heat shock/stress protein 70 (HSP 70)) to determine the integrated physiological responses in Oreochromis mossambicus to one metal (copper (Cu)) at a sub lethal level over the short term (96, 48, 24, 16, 12, 6, 4 and 2 h respectively). The information gained from these tests was valuable in suggesting what the baseline levels of biomarkers in O. mossambicus would be, as studies of metabolic adjustments to stress in fish have been focused on salmonids. The demand for sensitive, specific and rapid biological assays was also addressed by the development of an HSP 70 ELISA. This assay with, with additional refinement, will also prove to be a valuable tool in the management of Cu pollution in this species. Evaluation of the biomarkers in the gills of O. mossambicus indicated that this species has relatively high levels of MT in their gills compared with other species of fish. Exposure to sub lethal Cu concentrations [Cu] caused fluctuating, but not significant, levels in Na+K+ ATPase and HSP 70 during the exposure time, and the actual [Cu] in the gill seems to be the biggest factor when interpreting results. Significant decreases were found in MT levels in the gill tissue at 2 h and 12 h of exposure. HSP 70 results also indicated non-significant decreases to Cu exposure. Data from the gills analysed in the current study suggest that down-regulation in the biomarker response might be a better indicator of Cu exposure or effect in O. mossambicus. These data also suggest that further studies should rethink the amount of Cu that the fish under investigation would find sub-lethal as this metal seems to be very well regulated in this species of fish and seems frequently to non-significantly effect the chosen biomarkers. Evaluation of the biomarkers in the liver of O. mossambicus indicated that MT levels present in the liver most likely fall within the in range of normal baselevels for tilapia living in a Cu-rich environment and that HSP 70 in the liver only responds significantly to increased aqueous [Cu] at 16 h of exposure. This study also confirms current knowledge that the toxicity assessment of any pollutant, including Cu, cannot be exclusively based on one biomarker and that the true value of these biomarkers only becomes evident when they are used not as individual indicators but as integrated responses that influence one another. All these results furnish useful data for future research into the sub lethal effects of a pollutant such as Cu. The next step would be to test the usefulness of these physiological methods for detection of similar responses in natural fish populations inhabiting Cu polluted waters. This will provide a database relating the presence of Cu to biological effects at a molecular level. / Prof. J.H.J. Van Vuuren

The principal reason for the construction of Loskop Dam was to provide irrigation water to wheat farmers settling in the Olifants River valley in the 1920s. Agriculture has since developed in the area and today, the Loskop Irrigation Board supplies water to > 700 properties with an area of 25 600 ha farming cotton, wheat, citrus and grapes near the town of Groblersdal. Serious concerns were raised about deteriorating water quality when the crocodile population began to decline and the frequency of large fish kills increased from 2006. Crocodile (Crocodylus niloticus) and Mozambique tilapia (Oreochromis mossambicus) mortalities were linked to pansteatitis which is characterised by obesity and lipid peroxidation. Known impacts on water quality include eutrophication and acid mine drainage from coal mining with associated increases of soluble metals. The aims of this study were to: i) determine whether pansteatitis could be linked to any specific parameters in the water chemistry and limnology of Loskop Dam; ii) measure concentrations of aluminium, copper, iron, manganese, selenium and zinc in various tissues of O. mossambicus to determine whether bio-accumulation was occurring and could be related to pansteatitis; iii) assess the metazoan parasite communities of O. mossambicus to determine whether they are effective indicators of ecosystem health in Loskop Dam. Four established sampling sites were used at Loskop Dam and a reference site was located at neighbouring Kranspoort Dam. Surface water quality samples were collected monthly between July and December 2010 from each site and analysed for 27 constituents including nutrients, major ions, total metals, pH and dissolved oxygen using standard methods. Orthophosphate and total inorganic nitrogen results frequently categorised Loskop Dam as eutrophic and the transitional zone of the dam was characterised by very alkaline conditions resulting from algal blooms (median pH 9.67) which increase the solubility of metals like Al. A combination of active and passive biomonitoring techniques were used for fish collection. Fish gills, brain, muscle, liver and bone were analysed for Al, Fe, Mn, Zn, Cu and Se concentrations. The most striking result was an unanticipated significant deficiency in liver Cu concentrations of fish from Loskop Dam (mean 3.4 mg kg-1) compared to fish from Kranspoort Dam (mean 62 mg kg-1). Both endo- and ectoparasites were identified and enumerated on the fish and infection rates were calculated as mean intensity (I), mean abundance (A) and prevalence (P). Fish from Loskop Dam had extremely low infection rates and two fish had no parasites whatsoever. The ratio between monoxenous and heteroxenous parasites was calculated and was very high in fish from Loskop Dam compared to fish in Kranspoort Dam and Tompi Seleka, indicating a degraded aquatic ecosystem. While no single factor was outstanding as a possible cause of pansteatitis in this study, these findings provide a good foundation from which to formulate further research questions. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Paraclinical Sciences / unrestricted

O objetivo do presente estudo foi avaliar a hipótese de que a inclusão de licopeno na ração comercial reduz os efeitos negativos do estresse e melhora o desempenho de juvenis da tilápia do Nilo, Oreochromis niloticus. Para tal, foi realizado, primeiramente, um estudo que avaliou o efeito da suplementação com licopeno (100, 200, 400 e 800 mg/kg de ração) sobre a atrato-palatabilidade da ração. Numa segunda etapa foi avaliado o efeito da suplementação diária de licopeno (800 mg/kg de ração), durante 60 dias, na promoção do bem-estar de juvenis dessa espécie submetidos a estresse de contenção de 90 minutos. Foram avaliados parâmetros zootécnicos como ganho de peso, conversão alimentar, fator de condição e taxa de crescimento especifico, consumo e parâmetros fisiológicos e bioquímicos como o nível de cortisol plasmático, o conteúdo de peroxidação lipídica, avaliação da cor instrumental do file e a atividade das enzimas antioxidantes catalase (CAT) e glutationa redutase (GR) e atividade da lactato desidrogenase (LDH) no músculo branco (file) e vermelho. Os resultados foram submetidos a ANOVA e em caso de efeito significativo entre tratamentos, as medias foram comparadas pelo teste de Tukey (p<0,05). A inclusão de licopeno não alterou a atrato-palatabilidade da ração comercial em nenhuma das concentrações estudadas. A suplementação com licopeno (800 mg/kg de ração) não alterou nenhum dos parâmetros zootécnicos avaliados: ganho em peso, conversão alimentar, fator de condição e taxa de crescimento especifico. Da mesma forma, não alterou o nível de peroxidação lipídica avaliado pelas substancias reativas ao acido tiobarbitúrico (TBARS) e a cor instrumental do file dos peixes. Houve redução (34%) na atividade da catalase no músculo branco dos peixes suplementados com licopeno, comparado aos animais do grupo controle (sem suplementação). Entretanto, a atividade de catalase na musculatura vermelha não foi alterada mediante a suplementação com licopeno; bem como a atividade da GR e LDH no músculo branco e vermelho. Evidenciou que o estresse de contenção aumenta o nível de cortisol plasmático (53%), o nível de peroxidação lipídica do file (28%) e também a atividade de CAT, GR e LDH no músculo branco (31%, 32% e 29%, respectivamente) e músculo vermelho (48%, 46% e 44%, respectivamente) dos animais submetidos ao estresse. Porem, a inclusão de licopeno na dieta aboliu os efeitos negativos do estresse de contenção, evitando a elevação dos níveis de cortisol, conteúdo de TBARS do file e atividade das enzimas CAT, GR e LDH no músculo branco e vermelho. Concluiu-se que o licopeno veiculado na ração comercial, na proporção de 800 mg/kg de ração, reduz os efeitos negativos do estresse e não altera o desempenho de juvenis de tilápia do Nilo. / The aim of this study was to evaluate the hypothesis that the inclusion of lycopene in the commercial diet reduces the negative effects of stress and improves performance of juvenile Nile tilapia, Oreochromis niloticus. To this end was accomplished, first, a study that evaluated the effect of supplementation with lycopene (100, 200, 400 and 800 mg/kg of diet) on the attraction and palatability of the diet. In a second step, the effect of daily supplementation of lycopene (800 mg/kg of diet) for 60 days, to promote the welfare of juveniles subjected to restraint stress for 90 minutes. Zootechnical parameters were evaluated as weight gain, feed conversion, condition factor and specific growth rate, consumption and physiological and biochemical parameters as the plasma cortisol level, the content of lipid peroxidation, instrumental color of the fillet and the activity of antioxidant enzymes catalase (CAT) and glutathione reductase (GR) and activity of lactate dehydrogenase (LDH) in white muscle (fillet) and red muscle. The results were submitted to ANOVA and in case of significant effect between treatments, means were compared by Tukey test (p<0.05). The inclusion of lycopene did not affect the attraction and palatability of commercial feed in any of the concentrations studied. Supplementation with lycopene (800 mg/kg diet) did not alter any of the zootechnical parameters evaluated: weight gain, feed conversion, condition factor and specific growth rate. Likewise, did not alter the level of lipid peroxidation evaluated by thiobarbituric acid reactive substance (TBARS) and instrumental color of the fillet of fish. There was a reduction (34%) in catalase activity in white muscle of fish supplemented with lycopene, compared to the control group (no supplementation). However, catalase activity in red muscle was not altered by supplementation with lycopene, as well as GR activity and LDH in white muscle and red. It was demonstrated that restraint stress increased the plasma cortisol level (53%), level of lipid peroxidation of the fillet (28%) and activity of CAT, GR and LDH in white muscle (31%, 32% and 29%, respectively) and red muscle (48%, 46% and 44%, respectively) of animals subjected to stress. However, dietary supplementation with lycopene abolished the negative effects of stress restraint, avoiding high levels of cortisol, the TBARS content of the fillet and activity of enzymes CAT, GR and LDH in white muscle and red. It was concluded that lycopene aired the commercial feed at a ratio of 800 mg/kg of diet, reduces the negative effects of stress and does not alter the performance of juvenile Nile tilapia.

Uma das formas de se quantificar os possíveis efeitos de metais sobre o estado de saúde de organismo é analisar os biomarcadores do estresse oxidativo. Bioensaios foram realizados com a tilápia do Nilo (Oreochromis niloticus) com concentrações de cádmio (4,25 \'mü\'g/L), cobre (45,0 \'mü\'g/L ) e zinco (260,0 \'mü\'g/L). Os peixes foram expostos aos metais separados (\'CD\', \'CU\' e \'ZN\'), associados dois a dois (\'CD\'/\'CU\', \'CD\'/\'ZN\' e \'CU\'/\'ZN\') e aos três metais juntos (\'CD\'/\'CU\'/\'ZN\'), por doze dias. Foram retiradas amostras de rim, fígado e brânquias para análise de biomarcadores de estresse oxidativo, a superóxido dismutase (SOD), catalase (CAT) e glutationa peroxidase (GPx), o efeito da peroxidação de lipídios (HP), a glutationa S-transferase (GST) e a metalotionéina (MT). Pelos reusltados obtidos constatou-se que, mesmo nas baixas concentrações de exposição aos metais, ocorreram alterações no sitema de defesa antioxidante de O. niloticus. A primeira barreira antioxidante, composta pela SOD, não foi suficiente para barrar os efeitos da exposição aos metais. Em brânquias, onde a ativação desta enzima foi proeminente, formação de HP ocorreu. E, mesmo inicialmente em rim e fígado, tecidos onde ocorreu diminuição da atividade da SOD, ocorreu também a formaçao de HP nas etapas seguintes. A CAT e a GPx também atuaram no sentido de tentar evitar o aparecimento de HP, mas não foram bem sucedidas neste processo. A GST, como enzima da fase II de biotransformação pode ter auxiliado no processo de eliminação dos metais, mas como ocorre de forma tardia em relação à defesa antioxidante, acarretando danos celulares. Em relação às enzimas que compõem o sistema de defesa antioxidante não se verificou também especificidade de tecidos nas respostas. No entanto, a brânquia foi o órgão que teve maior intensidade nas respostas (em termos de ativação das enzimas), nos tratamentos de metais combinados dois a dois, evidenciando que este órgão, por estar em contato com a água e ser sede de processos fisiológicos de homeostase, desempenhou papel importante na tentativa de neutralizar os efeitos dos metais. / One way of quantifying metals effects upon organisms\' health state is to analyse oxidative stress biomarkers. Bioassays were conducted with Nile tilapia (Oreochromis niloticus) with cadmium (4,25 \'mü\'g/L), copper (45,0 \'mü\'g/L ) and zinc (260,0 \'mü\'g/L). Fishes were exposed to metals separatelly (\'CD\', \'CU\' e \'ZN\'), associated two by two (\'CD\'/\'CU\', \'CD\'/\'ZN\' e \'CU\'/\'ZN\') and to three metals together (\'CD\'/\'CU\'/\'ZN\'), for twelve days. Gills, liver and kidney samples were taken to analyse oxidative stress biomarkers, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), the effect of lipid peroxidation (HP), an enzyme of phase II biotransformation, glutathione S-transferase (GST) and metallothionein (MT). From results obtained, it was stablished that, even in low concentrations of metals, O. niloticus antioxidant defense system was modified. The first antioxidant barrier, SOD, wasn\'t able to minimize metal exposition effects. In gills, where activaton of this enzyme was prominent, didn\'t avoi HP formation. And even in liver and kidney, tissues where SOD activity decreased, HP formation also occurred. CAT and GPx also acted trying to avoid HP formation, but weren\'t successfull. GST, like a phase I enzyme, could help eliminating metals, but in a late moment in relation to antioxidant defense, leading to cell damage. For antioxidant enzymes no relation to tissue-specificity response was observed. But gills were the organ which had more intense responses (in terms of enzyme activation), mainly in metals combined two by two, evidencing that gills are important like a first organ in antioxidant defense because it is in direct contact with water and determine the main processes in homeostasis, trying to neutralize metals effects.

Uma das formas de se quantificar os possíveis efeitos de metais sobre o estado de saúde de organismo é analisar os biomarcadores do estresse oxidativo. Bioensaios foram realizados com a tilápia do Nilo (Oreochromis niloticus) com concentrações de cádmio (4,25 \'mü\'g/L), cobre (45,0 \'mü\'g/L ) e zinco (260,0 \'mü\'g/L). Os peixes foram expostos aos metais separados (\'CD\', \'CU\' e \'ZN\'), associados dois a dois (\'CD\'/\'CU\', \'CD\'/\'ZN\' e \'CU\'/\'ZN\') e aos três metais juntos (\'CD\'/\'CU\'/\'ZN\'), por doze dias. Foram retiradas amostras de rim, fígado e brânquias para análise de biomarcadores de estresse oxidativo, a superóxido dismutase (SOD), catalase (CAT) e glutationa peroxidase (GPx), o efeito da peroxidação de lipídios (HP), a glutationa S-transferase (GST) e a metalotionéina (MT). Pelos reusltados obtidos constatou-se que, mesmo nas baixas concentrações de exposição aos metais, ocorreram alterações no sitema de defesa antioxidante de O. niloticus. A primeira barreira antioxidante, composta pela SOD, não foi suficiente para barrar os efeitos da exposição aos metais. Em brânquias, onde a ativação desta enzima foi proeminente, formação de HP ocorreu. E, mesmo inicialmente em rim e fígado, tecidos onde ocorreu diminuição da atividade da SOD, ocorreu também a formaçao de HP nas etapas seguintes. A CAT e a GPx também atuaram no sentido de tentar evitar o aparecimento de HP, mas não foram bem sucedidas neste processo. A GST, como enzima da fase II de biotransformação pode ter auxiliado no processo de eliminação dos metais, mas como ocorre de forma tardia em relação à defesa antioxidante, acarretando danos celulares. Em relação às enzimas que compõem o sistema de defesa antioxidante não se verificou também especificidade de tecidos nas respostas. No entanto, a brânquia foi o órgão que teve maior intensidade nas respostas (em termos de ativação das enzimas), nos tratamentos de metais combinados dois a dois, evidenciando que este órgão, por estar em contato com a água e ser sede de processos fisiológicos de homeostase, desempenhou papel importante na tentativa de neutralizar os efeitos dos metais. / One way of quantifying metals effects upon organisms\' health state is to analyse oxidative stress biomarkers. Bioassays were conducted with Nile tilapia (Oreochromis niloticus) with cadmium (4,25 \'mü\'g/L), copper (45,0 \'mü\'g/L ) and zinc (260,0 \'mü\'g/L). Fishes were exposed to metals separatelly (\'CD\', \'CU\' e \'ZN\'), associated two by two (\'CD\'/\'CU\', \'CD\'/\'ZN\' e \'CU\'/\'ZN\') and to three metals together (\'CD\'/\'CU\'/\'ZN\'), for twelve days. Gills, liver and kidney samples were taken to analyse oxidative stress biomarkers, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), the effect of lipid peroxidation (HP), an enzyme of phase II biotransformation, glutathione S-transferase (GST) and metallothionein (MT). From results obtained, it was stablished that, even in low concentrations of metals, O. niloticus antioxidant defense system was modified. The first antioxidant barrier, SOD, wasn\'t able to minimize metal exposition effects. In gills, where activaton of this enzyme was prominent, didn\'t avoi HP formation. And even in liver and kidney, tissues where SOD activity decreased, HP formation also occurred. CAT and GPx also acted trying to avoid HP formation, but weren\'t successfull. GST, like a phase I enzyme, could help eliminating metals, but in a late moment in relation to antioxidant defense, leading to cell damage. For antioxidant enzymes no relation to tissue-specificity response was observed. But gills were the organ which had more intense responses (in terms of enzyme activation), mainly in metals combined two by two, evidencing that gills are important like a first organ in antioxidant defense because it is in direct contact with water and determine the main processes in homeostasis, trying to neutralize metals effects.

Made available in DSpace on 2015-03-26T13:54:39Z (GMT). No. of bitstreams: 1 texto completo.pdf: 196531 bytes, checksum: 00793dab89b8d4ee45d366f52e0d0f94 (MD5) Previous issue date: 2008-02-27 / The current study was aimed at evaluating the effect of digestible lysine levels in diet for Nile tilapia fingerlings (Oreochromis niloticus), of the thailand lineage based on the ideal protein concept in a 32 days trial. 432 Nile tilapia fingerlings with an average initial weight of 0.98 ± 0.03 g were allotted in a completely randomized design, with six treatments, six replications per treatment and twelve fish per experimental unit. The treatments had consisted of six isoenergetic (3.000 Kcal of DE/Kg of food) and isoproteic (39.14% of CP) diets with different levels of digestible lysine (1.50%, 1.66%, 1.82%, 1.98%, 2.14% and 2.30%). Feed intake, digestible lysine intake, weight gain, specific growth rate, survival rate, feed conversion, daily protein deposition rate, daily fat deposition rate, chemistry body composition (humidity, protein and fat content) and nitrogen retention efficiency were evaluated. The survival rate, body fat and humidity content, and body fat deposition on the fish was not affected by the level of digestible lysine of the diets. The increasing levels of lysine improved linearly the parameters of digestible lysine intake, feed conversion, body protein content and body protein deposition. However, the LRP (Linear Response Plateau) was the model which best fit the parameters of feed consumption, weight gain, specific growth rate and nitrogen retention efficiency, estimating at 2.06%, 2.17%, 2.14% and 2.12% the level of digestible lysine to maximize each of the parameters cited, respectively. It was concluded that the total and digestible lysine requirement for Nile tilapia fingerlings was 2,32% (0,773% / Mcal of DE) and 2,17% (0,723% / Mcal of DE), respectively, that correspond to a daily intake of 7,21 mg of total lysine and 6,67 mg of digestible lysine to meet the main parameters of performance (feed consumption, weight gain and specific growth rate) and carcass characteristics (nitrogen retention efficiency), when the ideal protein concept in the formulation of experimental diets was used. / Objetivando-se avaliar o efeito de níveis de lisina digestível em rações para alevinos de tilápia do Nilo (Oreochromis niloticus), linhagem tailandesa, com base no conceito de proteína ideal, realizou-se um experimento com duração de 32 dias. Foram utilizados 432 alevinos com peso inicial de 0,98 ± 0,03g, distribuídos em delineamento inteiramente casualizado composto por seis tratamentos, seis repetições e doze peixes por unidade experimental. Os tratamentos constaram de seis rações isoenergéticas (3000 Kcal de ED/Kg de ração) e isoprotéicas (39,14% de PB) com diferentes níveis de lisina digestível (1,50; 1,66; 1,82; 1,98; 2,14 e 2,30%). Os parâmetros avaliados foram: consumo de ração, consumo de lisina digestível, ganho de peso, taxa de crescimento específico, taxa de sobrevivência, conversão alimentar, taxas de deposição diária de proteína e gordura corporais, composição química corporal (teores de umidade, proteína e gordura corporais) e eficiência de retenção de nitrogênio. Não houve efeito do nível de lisina digestível das rações sobre a taxa de sobrevivência, umidade e porcentagem de gordura corporal e deposição de gordura corporal dos peixes. O aumento dos níveis de lisina digestível melhorou linearmente os parâmetros de consumo de lisina digestível, conversão alimentar, porcentagem de proteína corporal e deposição de proteína corporal. Entretanto, o LRP (Linear Response Plateau) foi o modelo de melhor ajuste para os parâmetros de consumo de ração, ganho de peso, taxa de crescimento específico e eficiência de retenção de nitrogênio, estimando em 2,06%, 2,17%, 2,14% e 2,12% o nível de lisina digestível para maximizar cada um dos parâmetros citados, respectivamente. Conclui-se que a exigência de lisina total e digestível em rações para alevinos de tilápia do Nilo é, respectivamente de 2,32% (0,773% / Mcal de ED) e 2,17% (0,723% / Mcal de ED), correspondente ao consumo diário de 7,21 mg de lisina total e 6,67 mg de lisina digestível, para atender aos principais parâmetros de desempenho (consumo de ração, ganho de peso e taxa de crescimento específico) e características de carcaça (eficiência de retenção de nitrogênio), utilizando-se o conceito de proteína ideal na formulação das rações experimentais.

Submitted by GUSTAVO MACIEL PIZZATO null (gustavopizzato@yahoo.com.br) on 2017-08-28T16:55:18Z No. of bitstreams: 1 Dissertação - GPIZZATO_CAUNESP.pdf: 2983120 bytes, checksum: 7b85627b7257e65769af9dc1f32991b0 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-29T17:49:12Z (GMT) No. of bitstreams: 1 pizzato_gm_me_jabo.pdf: 2983120 bytes, checksum: 7b85627b7257e65769af9dc1f32991b0 (MD5) / Made available in DSpace on 2017-08-29T17:49:12Z (GMT). No. of bitstreams: 1 pizzato_gm_me_jabo.pdf: 2983120 bytes, checksum: 7b85627b7257e65769af9dc1f32991b0 (MD5) Previous issue date: 2017-06-30 / Outra / A piscicultura intensiva em tanques-rede alocados em reservatórios artificias é um modelo viável de produção, no qual o desenvolvimento da tilápia é favorecido. Porém, o manejo alimentar em tanques-rede merece atenção extra, visto a grande participação da ração no custo de produção. Estratégias alimentares que aliem bom desempenho produtivo ao menor custo são fundamentais para a lucratividade e o desenvolvimento da atividade. O objetivo deste estudo foi estabelecer um protocolo adequado de fornecimento de ração para tilápias em tanques-rede na fase de terminação que favorecesse o desempenho produtivo e econômico dos peixes. Avaliaram-se estratégias alimentares com utilização de um dia de jejum semanal, ajuste da quantidade de ração conforme o consumo em diferentes tempos de tolerância (cinco, 15 e 25 minutos) e um controle, com tabela de alimentação. O delineamento foi em blocos casualizados, esquema fatorial 2x3, com sete repetições para cada estratégia alimentar e seis para o controle. Ao final do experimento, o jejum reduziu em 15% o índice de gordura víscero somático dos peixes. A estratégia com ajuste da ração conforme observação do consumo após 15 minutos proporcionou maiores valores de peso final, ganho em peso e melhor conversão alimentar. Embora a utilização da tabela de alimentação tenha levado à menor produtividade, o menor custo operacional total (COT) nesta estratégia assegurou lucro operacional médio satisfatório. A adoção do jejum reduziu o custo com mão de obra, embora sem alterações importantes no COT, uma vez que tal prática proporcionou menores produtividades e pior conversão alimentar. Assim, conclui-se que a estratégia alimentar sem jejum semanal e com quantidade de ração ajustada conforme o consumo em 15 minutos gera maior produtividade e menor COT médio, garantindo o maior lucro operacional e margem bruta. / Intensive fish farm with cages placed in artificial reservoirs is an interesting production model, in which the tilapia development is favored. However, the feed management in cages deserves extra attention, considering the high ration participation in the production cost. Feed strategies that combine good productive performance at the lowest cost are essential to the profitability and development of the activity. The aim of this study was to establish an appropriated protocol for feed supply tilapia in cages at the finishing phase that provide better productive and economic performance. Feed strategies considered a weekly fasting day, adjustment of the daily feed according to the consumption in different tolerance periods (five, 15 and 25 minutes) and a control, feeding the fish according to a feeding table. The experimental design was a randomized complete block design, 2x3 factorial scheme, with seven replicates for each feeding strategy and six for the control. At the end of the trial, the fasting reduced the visceral somatic index by 15%. The strategy that adjust the feed considering the consumption in 15 minutes provided higher values of final weight, weight gain and better feed conversion rate. Although the feed table led to lower productivity, the lower total operating cost (TOC) in this strategy ensured a good average operating profit. The adoption of fasting reduced labor cost, although without significant changes in TOC, since this practice provided lower productivity and worst feed conversion rate. Thus, it was concluded that the strategy without a weekly fasting and with the feed adjustment according to the consumption in 15 minutes provide higher productivity and lower average TOC, which ensure the highest operating profit and gross margin.

Made available in DSpace on 2014-12-17T14:33:04Z (GMT). No. of bitstreams: 1 FranciscoRV_DISSERT.pdf: 943640 bytes, checksum: d6134d4d93c5e755e9cda7290579f131 (MD5) Previous issue date: 2010-07-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The omnivorous filter-feeding fish, Nile tilapia (Oreochromis niloticus), can have negative effects on water quality enhancing the eutrophication process. These effects depend on the nutrient enrichment level in the water. We carried out a mesocosm experiment for five weeks in a tropical man-made lake in Brazil to test ifthe effects of tilapias depend on of the level of nutrient enrichment. The experiment lasted for 5 weeks and a factorial 2x5 experimental design was used where the presence and absence of tilapias were manipulated in combination to 5 different levels of nutrient load in a total of 10 treatments. A two way repeated measure ANOVA was performed to evaluate the effects of time (t), tilapia (F), nutrients (NP) and the interactions among these factors on: chlorophyll a, water transparency, total phosphorous, total nitrogen, N:P ratio, zooplankton biomass and phytoplankton biovolume. The tilapia effect was evident, but nutrient enrichment didn t have any effect on the variables analyzed. Tilapia decreased the water transparency, total zooplankton biomass, calanoid copepod biomass, nauplii copepod biomass and cladocerans biomass. On the other hand, tilapia had no effect on phytoplankton biovolume. This lack of effect on phytoplankton is probably due to tilapia grazing that may counteract the positive effect of tilapia on phytoplankton via trophic cascades and nutrient recycling. Hence, a reduction in tilapia stock would not be an effective way to reduce phytoplankton biomass and improve water quality / A til?pia do Nilo (Oreochromis niloticus) ? um peixe on?voro filtrador que pode ter efeitos negativos sobre a qualidade da ?gua favorecendo o processo de eutrofiz??o. Esses efeitos negativos dos peixes on?voros filtradores devem ser dependentes do n?vel de enriquecimento da ?gua por nutrientes. N?s realizamos um experimento em mesocosmos por cinco semanas em um lago artificial tropical para testar se os efeitos das til?pias s?o dependentes do n?vel de enriquecimento por nutrientes. O experimento teve dura??o de 5 semanas e consistiu num delineamento fatorial 2x5 onde 2 n?veis de til?pia (presen?a e aus?ncia) foram manipulados em combina??o com 5 diferentes niveis (aportes) de nutrientes num total de 10 tratamentos.. Uma ANOVA bifatorial com medidas repetidas no tempo foi realizada para testar os efeitos do tempo (t), da til?pia (F) e do nutriente (NP) e os efeitos de suas intera??es sobre a clorofila a, transpar?ncia do disco de Secchi, concentra??o de f?sforo e nitrog?nio total e a raz?o entre eles (N:P), al?m do efeito sobre a biomassa da comunidade zooplanct?nica e o biovolume de fitopl?ncton. O efeito da til?pia foi evidente, enquanto o enriquecimento por nutrientes n?o mostrou efeito algum. Quando presente, a til?pia diminuiu a transpar?ncia do disco de Secchi e a biomassa total do zoopl?ncton, de cop?podos calan?ides, na?plios de cop?podos e de clad?ceros. Por?m, nenhum efeito foi detectado da til?pia sobre o biovolume do fitopl?ncton. Essa aus?ncia de efeito pode ser devido a herbivoria da til?pia que contrabalan?a os seus efeitos positivos via cascata tr?fica e ciclagem de nutrientes. Desta forma, uma redu??o do estoque pesqueiro de til?pias para promover uma melhoria na qualidade da ?gua n?o afetaria a biomassa fitoplanct?nica e consequentemente n?o atingiria o seu objetivo