Orientador: Elisa Helena Giglio Ponsano / Banca:Rachel Cristina Prehl Alves / Banca: Silvia Helena Venturoli Perri / Resumo: O tom avermelhado de alguns peixes age como um fator distintivo em relação ao pescado convencional de carne branca, agregando valor e propiciando o surgimento de um novo produto. Por esse motivo, o estudo de fontes pigmentantes para utilização em dietas de peixes de importância econômica é assunto de considerável interesse para a aquicultura e a indústria de alimentos. O objetivo deste trabalho foi avaliar o efeito de diferentes fontes de carotenoides adicionados à ração de tilápias sobre o desempenho zootécnico e as características de qualidade dos filés. Novecentas e sessenta tilápias (Oreochromis niloticus) pesando entre 10 - 30 g foram distribuidas em 24 tanques e, após um período de adaptação, receberam as rações experimentais durante 80 dias. Os tratamentos foram constituídos de um grupo controle, correspondente a uma dieta basal sem aditivos pigmentantes, um grupo contendo astaxantina e quatro grupos contendo diferentes concentrações da biomassa de Rubrivivax gelatinosus como aditivo pigmentante. As variáveis analisadas incluíram consumo de ração, ganho de peso e conversão alimentar aparente das tilápias e pH, composição centesimal, concentração de carotenoides e cor dos filés. Os índices zootécnicos não diferiram estatisticamente, indicando que o uso dos pigmentantes não causou prejuízo ao desempenho produtivo. Os teores de umidade dos grupos que receberam pigmentantes foram inferiores aos encontrados nos filés do grupo controle, sendo este resultado relevante para a estabilidade microbiológica. O teor proteico dos filés dos grupos suplementados com biomassa bacteriana foi superior ao do grupo controle e os valores de pH, cinzas e lipídeos não variaram entre os tratamentos. A luminosidade e a intensidade de amarelo dos filés não diferiram entre os grupos e todos os tratamentos contendo pigmentantes provocaram aumento na intensidade...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The reddish hue of some fish acts as a distinctive factor from traditional white flesh, adding value to the product and providing a new product to consumer market. Because of that, the investigation on pigmenting sources for the diets of fish with economic importance is a matter of great interest for aquaculture and food industry. The aim of this work was to evaluate the effects of different carotenoids sources in tilapia fish diets on animals' performance and fillets characteristics. Nine hundred sixty tilapias (Oreochromis niloticus) weighing 10 - 30 g were distributed in 24 tanks and, after an adaptation time, they received the experimental diets for 80 days. Treatments consisted of one control group receiving a basal diet with no pigment, one group receiving asthaxanthin and four groups receiving different concentrations of Rubrivivax gelatinosus biomass as the pigmenting ingredient. Variables analyzed included feed consumption, weight gain and feed conversion for the animals and pH, proximate composition, carotenoids content and color for the fillets. Productive parameters did not differ statistically, showing that the use of the pigments did not cause any damage to animals' performance. Moisture contents of the fillets from the groups that received pigments were lower than those in the fillets from control group, what represents an important factor for the product conservation. The protein contents of the fillets from diets supplemented with the bacterial biomass were higher than those in control group while pH, ash and lipids did not vary among treatments. Lightness and yellowness did not differ among the groups but redness and carotenoids contents were higher for the fillets from all groups that received the pigments than for the control group. So, it can be concluded that the use of the pigmenting ingredients did not alter productive parameters but increased...(Complete abstract eletronic access below) / Mestre

Orientador: Maeli Dal Pai Silva / Banca: Margarida Maria Barros / Banca: Fabíola Valdez Domingues / Resumo: A tilápia do Nilo (Oreochromis niloticus L.), amplamente utilizada na piscicultura brasileira, destaca-se por apresentar inúmeras qualidades para o mercado consumidor. Assim como ocorre com outras espécies de peixes, o desenvolvimento muscular das tilápias pode sofrer a influência de diversos fatores (extrínsecos e intrínsecos), podendo assim comprometer os custos de produção. Neste estudo, objetivamos avaliar a morfologia e a expressão de genes que controlam o crescimento muscular em tilápia do Nilo (Oreochromis niloticus) da linhagem GIFT cultivada em diferentes temperaturas. Noventa peixes (n=10) de uma população monosexo de machos revertidos, pesando aproximadamente 1,4 g, foram distribuídos aleatoriamente em seis caixas d'água de 0,5 m3 em sistema de recirculação d'água e cultivados em três diferentes temperaturas (22, 28 e 30° C) durante 7, 30 e 60 dias. Foram realizadas análises biométricas e morfológicas, bem como análises de expressão gênica dos fatores reguladores miogênicos (MyoD e Miogenina) e do fator de crescimento Miostatina. A análise de expressão gênica foi realizada através da técnica de Reação em Cadeia da Polimerase em Tempo Real após Transcrição Reversa (qRT-PCR). Os dados de peso(g) e comprimento padrão (cm) demonstraram que a temperatura pode influenciar o ganho de peso final, sendo que os animais cultivados a 22°C apresentaram menor peso a partir do 30º dia, quando comparado com os animais cultivados a 28 e 30°C. A análise morfométrica (distribuição do diâmetro médio das fibras), não apresentou diferenças significativas entre os animais nas temperaturas estudadas. Entretanto, os animais cultivados a 22 e 30°C apresentaram comportamento similar na distribuição do diâmetro médio das fibras. A análise de expressão gênica para a MyoD, apresentou os maiores... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The Nile tilapia (Oreochromis niloticus L.), widely used in Brasilian aquaculture, stands out for its numerous qualities to the consumer market. As with other fish species, tilapia muscle development may be influenced by several factors (extrinsic and intrinsic) and, thus, it can lead to compromise production costs. This study aimed to evaluate the morphology and expression of genes that control muscle growth in Nile tilapia (Oreochromis niloticus) of GIFT strain grown at different temperatures. Ninety fish (n = 10) of a reverted males monosex population, weighing about 1.4 g were randomly divided into six water tanks of 0.5 m3 of water recirculation system and reared in three different temperatures (22, 28 and 30 ° C ) for 7, 30 and 60 days. It was performed biometric and morphological analysis, along with gene expression of myogenic regulatory factors (MyoD and myogenin) and growth factor myostatin analysis. The gene expression analysis was performed using the technique of Polymerase Chain Reaction Real-Time after Reverse Transcription (qRT-PCR). Weight (g) and standard length (cm) data showed that temperature can influence final weight gain, and the animals grown at 22 ° C had lower weight from the 30th day, when compared with animals reared at 28 and 30 ° C. The morphometric analysis (distribution of the fiber mean diameter), did not show significant differences among animals in the studied temperatures. However, animals reared at 22 and 30 ° C showed similar behavior in the distribution of the fiber mean diameter. The gene expression analysis for MyoD, showed the highest mRNA levels in animals grown at 22 ° C, when compared to animals reared at 28 and 30 ° C in almost all studied periods. The levels of mRNA for the myogenin were constant at all studied temperatures and periods. At seven days... (Complete abstract click electronic access below) / Mestre

Orientador: Rodrigo Yudi Fujimoto / Banca: Claudinei da Cruz / Banca: Eduardo Makoto Onaka / Resumo: O Selênio é um mineral constituinte de uma série de enzimas antioxidantes que atuam protegendo as membranas celulares dos danos causados pelo processo de oxidação. Sua deficiência ou excesso na dieta pode resultar em depressão do crescimento e aumento da taxa de mortalidade. O objetivo deste estudo foi avaliar o efeito da suplementação da dieta em jovens de tilápia do Nilo (Oreochromis niloticus) com quatro níveis de selenometionina (0,25; 0,50; 1,0; e 1,5 mg Se/kg) e um grupo controle (0,0 mg Se/kg) no desempenho produtivo (ganho de peso, conversão alimentar aparente, taxa de crescimento específico e consumo de ração), nos índices hepatossomático e esplenossomático, na histopatologia do fígado, no índice de parasitismo por monogenea e na hematologia. O consumo de ração aumentou proporcionalmente ao nível de Se nas dietas. Os índices de desempenho produtivo não apresentaram diferenças significativas, no entanto, as concentrações intermediárias (0,25 e 0,50 mg Se/kg) aumentaram o ganho de peso, diminuíram a conversão alimentar e não apresentaram alterações significativas no estrutura morfofuncional do fígado. Não ocorreu diferença significativa para as variáveis hematológicas estudadas e para o índice de parasitismo por monogenea, porém, observou-se que nos níveis de 0,50 e 1,0 mg Se/kg o número de parasitos foi menor em relação às demais concentrações. Assim, pode-se concluir que a melhor suplementação está entre os níveis de 0,25 e 0,50 mg Se/kg de ração. / Abstract: Selenium is an important micronutrient for animals, essential for the normal life processes. This mineral is a constituent of the enzyme antioxidant glutathione peroxidase, of deiodinase and of thioredoxin reductase. The deficiency or toxic levels in feed can be result in growth depression and mortality. The objective of this study was to evaluate the selenomethionine effects for juveniles Nile tilapia (Oreochromis niloticus) on the growth performance (weight gain, index of alimentary conversion, specific growth rate, diet consumption and index of alimentary efficiency), hepatossomatic and esplenossomatic index, liver histopathology, parasitism and haematology, submitted to four levels of selenium in feed (0.25, 0.50, 1.0, and 1.5 mg Se/kg diet) and control group (0.0 mg Se/kg). The results did not show difference, however, the levels of 0.25 and 0.50 mg Se/kg improve the growth performances evaluated and did not show liver histopathology damage. No differences were observed in haematological parameters. The total count of monogeneans reduced in the levels of 0.50 and 1.0 mg Se/kg of diet but without differences due the elevated coefficient of variation. In conclusion the ideal supplementation level was between 0.25 and 0.50 mg Se/kg. / Mestre

Orientador: Edmir Daniel Carvalho / Banca: Katharina Eichbaum Esteves / Banca: Gianmarco Silva David / Resumo: O presente trabalho teve como objetivo estudar o regime alimentar de Oreochromis niloticus (Linnaeus, 1758) e Tilapia rendalli (Boulenger, 1897) na represa de Barra Bonita, Médio Rio Tietê, SP, utilizando-se duas abordagens: i) caracterização das dietas de O. niloticus e T. rendalli, e possíveis relações com a aceleração do processo de eutrofização e ii) variação ontogenética e padrões sazonais do regime alimentar dessas espécies. As amostragens foram realizadas mensalmente (março de 2007 a fevereiro de 2008) no município de Anhembi (SP). Os peixes foram obtidos do desembarque da pesca artesanal e paralelamente, foi realizada a pesca experimental com uso de tarrafas de malha 3 cm entrenós não adjacentes, visando amostrar exemplares de pequeno porte. Foram coletados ainda fatores abióticos da água (oxigênio dissolvido, temperatura da água, pH e condutividade elétrica, transparência da água e clorofila-a total). Outros dados como cota altimétrica da represa e pluviosidade mensal foram compilados da concessionária AES - Tietê. De todos os exemplares de peixes foram obtidos dados biométricos (comprimento padrão e peso total). Os estômagos foram transferidos para frascos etiquetados contendo solução de formaldeído 10%. O conteúdo estomacal foi analisado pelos métodos de freqüência de ocorrência e volumétrico, combinados no Índice alimentar. Para avaliar as possíveis variações ontogenéticas e sazonais, foram analisadas as dietas dos exemplares de cada espécie agrupados em classes de tamanho e por estação seca e chuvosa. Na dieta das duas espécies foram observados 26 itens alimentares agrupados em sete categorias (fragmentos vegetais, algas, detritos, peixes, microcrustáceos, macroinvertebrados e insetos aquáticos). A espécie O. niloticus, consumiu 24 itens, e foi considerada detritívora, enquanto que T. rendalli, consumiu... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present work aimed to study the food habits of niloticus (Linnaeus, 1758) and Tilapia rendalli (Boulenger, 1897) in the Barra Bonita reservoir, São Paulo State, by using two approaches: i) characterization of O. niloticus e T. rendalli feeding habits and to find any possible relationship with the reservoir's eutrophication process and ii) analyze seasonal and ontogenetic variation with regard to the diet of these species. Samples were collected monthly, from March 2007 to February 2008, in Anhembi, São Paulo State. The fishes were obtained of artisanal fish landing and fishing was done using casting net (3cm between-knot mesh size), to get small individuals. Some physico-chemical variables of water samples were collected (dissolved oxygen, water temperature, pH and electric conductivity, water transparency and chlorophyll a). Another data such as reservoir altimeter quota and monthly rainfall were gathered from the AES - Tietê. Biometric data (standard length and total weight) were obtained from all individuals. The stomachs were transferred to labeled bottle with formaldehyde 10%. The stomach content was analyzed by frequency of occurrence and volume, combined on the food index. To evaluate possible seasonal and ontogenetic variation, it was analyzed the diet of each species grouped in size class and by dry and wet season. In the diet of both species were observed 26 different food items grouped into seven categories: vegetables fragments, algae, detritus, fishes, micro crustaceans, macro invertebrates and aquatic insects). O. niloticus consumed 24 items, and was considered detritivorous, whereas T. rendalli consumed 23 items, and was considered omnivorous, because it used animal and vegetal resources without dominance of any no category. With regard to a possible relationship with the reservoir's eutrophication process, this could be mitigated by species, given that the feed... (Complete abstract click electronic access below) / Mestre

Orientador: Julieta Rodini Engrácia de Moraes / Banca: Julio Hermann Leonhardt / Banca: Fabiana Pilarsky / Resumo: A vitamina E ou tocoferol é um importante nutriente que atua como imunoestimulante em peixes. No presente estudo foi verificado o efeito deste nutricêutico no processo de cicatrização induzido em tilápia do Nilo, suplementadas ou não com 450 mg de vitamina E. Exemplares desta espécie foram separados em dois grupos contendo 90 peixes, denominados controle e suplementados, distribuídos em 18 caixas de água com capacidade de 250L com 10 exemplares em cada. Os peixes foram alimentados durante 60 dias com as rações experimentais. Após este período, todos os peixes foram anestesiados e submetidos às cirurgias, onde feridas cutâneas de tamanho padronizado e representativas do processo cicatricial foram realizadas cirurgicamente com remoção da epiderme e derme. A análise histomorfométrica foi verificada após três, sete, 14, 21 e 28 dias. Foram utilizados como parâmetros para análise macroscópica: índice de retração cicatricial e aparência das feridas, e para a microscópica: histomorfometria de células mucosas, cromatóforos, neovasos, células inflamatórias, fibroblastos, fibras de colágeno e escamas. Os resultados mostraram que o índice de retração cicatricial foi significativamente maior no grupo suplementado, fato atribuído à contribuição do maior número de células inflamatórias, células mucosas, cromatóforos e a maior produção e organização das fibras de colágeno que foram significativamente maiores nos diferentes tempos, neste grupo. Os resultados indicam que o efeito nutricêutico da vitamina E promove o processo de reparação tecidual. / Abstract: The vitamin E or tocoferol is an important nutrient that acts as an imunoestimulant in fishes. In the present study the effect of this vitamin was appraised in the process of induced wound healing in Nile tilapias Oreochromis niloticus supplemented with 0 and 450 mg levels of vitamin E. Examples from this specie were separated in two groups with 90 fishes in each, denominative control and supplemented, distributed in 18 boxes of water with capacity of 250L with 10 examples in each. The fishes were fed during 60 days with the experimental rations. After this period, all the fishes were anaesthetized and submitted the surgeries, where cutaneous wounds of standardized size and representative of the wound healing process were carried out by them surgically with removal of the epidermis and derme. The histomorphometric analysis was checked after three, seven, 14, 21 and 28 days post-wounding. They were used parameters for macroscopic as analysis rate of cicatricial retraction and appearance of the wounds, and for the microscopic one, histomorphometric of mucous cells, cromatophores, revascularization, inflammatory cells, presence of fibroblasts, fibers of collagen and scales. The results show the rate of retraction of the wound was significantly higher in the supplemented group. This higher rate of retraction results from the contribution of each microscopic parameter analyzed, such as inflammatory cells, mucous cells and cromatophores that were significantly higher in the different times, as the production and organization of collagen fibers. The results indicate that the vitamin E promotes wound healing process. / Mestre

Made available in DSpace on 2014-06-11T19:30:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-29Bitstream added on 2014-06-13T18:40:06Z : No. of bitstreams: 1 pomari_j_me_botib.pdf: 1726269 bytes, checksum: e6e60f4bcdd97a4244794afc993031a9 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O Brasil possui uma imensa rede de reservatórios artificiais que são utilizados para múltiplas finalidades, entre elas a piscicultura em tanques-rede. A implantação de sistemas de cultivo em tanques-rede está se desenvolvendo em larga escala, inclusive com incentivos governamentais. É importante lembrar que este tipo de cultivo emprega um volume considerável de insumos para sua produção, gerando uma grande quantidade de resíduos orgânicos e inorgânicos que podem levar a eutrofização das áreas aqüícolas e mudanças nas comunidades aquáticas. Os organismos zooplanctônicos são tidos como elos estruturadores das cadeias alimentares aquáticas, podendo inclusive ter um papel complementar na tilapicultura em tanques redes. Podem ainda ser considerados como indicadores da qualidade de água. O presente trabalho tem por objetivo analisar a composição, riqueza, abundância e diversidade das assembléias zooplanctônicas (Rotifera, Cladocera e Copepoda), e sua relação com mudanças potenciais do grau de trofia relacionadas à implantação de tanques-rede. Os trabalhos de campo foram conduzidos durante um ciclo sazonal completo (novembro de 2006 a novembro de 2007) nas zonas de transição rio-reservatório (Fartura, SP) e na barragem (Chavantes, SP) do reservatório de Chavantes, Rio Paranapanema. São Paulo. As amostragens foram realizadas em áreas com a presença de tanques-rede, bem como em áreas controle, sem efeito da tilapicultura. Além do zooplâncton também foram considerados as variáveis limnológicas (coluna d’água) temperatura, pH, oxigênio dissolvido, condutividade elétrica, transparência, turbidez, clorofila, nitrogênio orgânico total e fósforo total. As influências dos sistemas de cultivo em tanques-rede nas regiões de Chavantes e Fartura, reservatório de Chavantes, rio Paranapanema (SP/PR) puderam ser observadas no presente estudo... / Brazil has a complex network of artificial reservoirs that are used for multiple purposes, including fish farming in cage aquaculture systems. The introduction of cultivation systems in net cages has been is a large-scale development process, which receives governmental incentives. This kind of zootechnical production requires a considerable amount of ration and sanitary products, generating a large quantity of organic and inorganic wastes that can lead to eutrophication of the aquaculture areas. As a consequence it is expected a decrease in the water quality and modifications in the aquatic community. The zooplankton organisms are considered as basic links in the aquatic food webs, and may also have a complementary role in the net cage tilapiculture. The assemblages structure can also be considered as indicators of water quality. This work aimed to analyze the composition, richness, abundance and diversity of the zooplankton assemblages (Rotifera, Cladocera and Copepoda), and its relation to the potential changes of the trophic level related to the introduction of net cages farms. The field work was conducted during a complete seasonal cycle (November 2006 to November 2007) in the river-reservoir transition zone (Fartura, São Paulo State) and in the dam zone (Chavantes, São Paulo State) of Chavantes Reservoir (Paranapanema River, São Paulo/Paraná States). Samplings were taken monthly in areas with the presence of net cages, as well as in control areas (without the tilapiculture effects). Besides the zooplankton the limnological variables (water column) temperature, pH, dissolved oxygen, electrical conductivity, transparency, turbidity, chlorophyll, total organic nitrogen and total phosphorus were also analyzed. The influence of the fish cultivation systems in the regions could be observed. Due to the eutrophication process, changes in physical and chemical water characteristic... (Complete abstract click electronic access below)

M.Sc. / Aquatic toxicology is the qualitative and quantitative study of toxic effects of pollutants on aquatic organisms. The main goal in toxicity testing is to predict, in combination with other environmental factors, with known accuracy, a concentration of a specific toxicant that will not harm a system and to make this prediction in a responsible and cost effective manner. There are a variety of unique toxicity tests, with fish being one of the most popular organisms to work with, due to being the best-understood organism in the aquatic environment and its commercial importance. Zinc, copper and cadmium are three biologically important heavy metals that are commonly used in various industries. Low concentrations zinc and copper are essential micronutrients for both plants and animals, but in higher concentrations they become toxic to the environment and its biota. Cadmium has a chemical structure similar to that of zinc and is often found in association with it, but it is a very toxic substance. The effects of zinc, copper and cadmium on the free-embryo life stage (yolk sac phase) of Oreochromis mossambicus were examined, for evaluation as a possible ¡§early life stage¡¨ fish lethality assessment. ¡§Fish early life stage tests¡¨ are considered to be relatively quick, comparable and inexpensive screening tools for testing effluents and chemicals. The yolk-sac stage is considered the most sensitive life stage in fish. O. mossambicus free-embryos feed endogenously and are indigenous to southern Africa and are therefore a good choice for lethality testing. The effects of the same metals on randomly selected Culicidae (mosquito) larvae were also tested. The reason for randomly selected larvae was to determine the possibility of doing toxicity testing without a species-specific culture. Mosquitoes are very common and well known due to being vectors of various human diseases. Recommendations towards future studies, to determine the usefulness of both O. mossambicus embryos and Culicidae larvae as biological indicator organisms, were also looked at. / Prof. G.J. Steyn

No description available.

A histological assessment allows aquatic scientists to assess fish health in polluted aquatic ecosystems at tissue and cellular level. However, a firm knowledge and understanding of normal histological structure is essential to ensure accurate and objective results. Hence, the histologist must be able to distinguish between toxicant induced lesions and the range of histological characteristics considered to be normal for that specific species. However, limited histological reference material and data describing normal conditions are available for southern African fish species. The aim of this baseline study was to establish reference material, both qualitative and quantitative, for two southern African freshwater fish species used as indicator species in toxicity studies at the University of Johannesburg, Clarias gariepinus and Oreochromis mossambicus. The reference material includes descriptive histology of selected target organs, and the associated values and intervals for related quantitative health aspects including somatic indices, condition factor, blood parameters (haematocrit and plasma proteins) and quantitative histological results. Essentially, this project originated from a need to better understand the normal histology of C. gariepinus and O. mossambicus, as a range of histological characteristics were identified in control groups in previous toxicity studies which could not be confirmed to be associated with normal conditions. To be able to conduct a baseline study, with the purpose of establishing reference material, it was essential that the history of the specimens be known and documented including age, sexual maturity, nutritional status and physical and chemical water quality data. The project therefore involved the breeding of fish specimens under controlled conditions. A subsequent necropsy and qualitative and quantitative histological assessments were executed on five target organs (usually included in toxicity studies within the department): liver, gills, gonads, heart and kidney. Fish of both species were bred in an environmental room in reconstituted, reverse osmosis water and reared until sexually mature. Twenty specimens with an approximately 50:50% sex ratio were collected for both species. A necropsy was performed on each specimen and tissue samples of the selected target organs were processed using standard techniques, and prepared for the qualitative and quantitative histological assessments using light microscopy. The results The results showed that no macroscopic abnormalities were identified during the necropsy regarding external features or internal organs of the specimens within the sample groups, and all fish appeared to be in good health. The target organs were then examined microscopically, followed by a description of the normal histological structure (qualitative assessment). In addition, the target organs were assessed by means of a specific quantitative histological assessment protocol, which provides a standardised methodology of criteria to objectively assess fish health (quantitative assessment). Histological alterations identified during this assessment were quantified and subsequent reference index values could be calculated for each organ. / Dr. G.M. Pieterse

The need to monitor fresh water ecosystems for pollution is increasing, as is the need to develop a biomarker sensitive to a range of environmental insults. Recently, heat shock proteins have been identified as possible biomarkers of environmental contamination. However, evaluation as to their use as a biomarker of metal contamination in fish species endemic to Southern Africa is limited. The purpose of this study was to identify what members of the 70 kDa family of heat shock proteins (Hsp70) were present in the liver of Oreochromis mossambicus, and if their accumulation was altered after short-term (96 hour) exposure to aqueous copper. In addition to copper exposure, the effect of acclimation media was also examined. Tissue-level analysis was done by means of histological examination so as to determine if alterations in the accumulation of the Hsp70 family had a marked effect on the structural integrity of the liver. Specimens of Oreochromis mossambicus acclimated in either aged tap water or borehole water were placed in flow-through systems and exposed to either 10% or 20% of the LC50 value of cupric chloride for a duration of 96 hours. Control groups were run in conjunction with the exposure groups so as to set control values by which to compare. Heat shock protein analysis was done by Western blotting after separation of hepatic proteins by SDS-PAGE. For the purpose of histological analysis, representative samples were randomly selected. Analysis of the hepatic heat shock protein 70 family identified the presence of three (3) members, each of a different molecular weight. These included members of 70 kDa (Hsp70), 74 kDa (Hsp74) and 76 kDa (Hsp76). In addition to these findings, it was found that Oreochromis mossambicus accumulated high levels of particular members of the heat shock protein 70 family under unstressed conditions, affording the fish adaptability to environmental extremes. Furthermore, individuals acclimated in aged tap water showed decreased Hsp76 accumulation after exposure to sub-lethal copper concentrations, whereas those individuals acclimated in borehole water retained relatively high levels of Hsp76. Additionally, it was shown that the hepatic structure deteriorated in those individuals acclimated to the aged tap water after copper exposure, with observed increases in vacuolation, number of macrophage centres present and the occurrence of intracellular golden-brown granules. However, there was little change from the already-altered hepatic structure of those individuals acclimated in borehole water, with conspicuous golden-brown granules the most obvious histopathological condition present. Histological examination therefore proved to supplement the heat shock protein results obtained. This study thus concluded that a decrease in the accumulation of the Hsp70 family resulted in a negative organismal response, initiating deleterious alterations in the hepatic structure. Additionally, this study concluded that past water quality has a marked effect on a given biomarker response, and should be taken into careful consideration when conducting biomarker studies. / Prof. J.H.J. Van Vuren