Lagoas costeiras são ecossistemas cruciais para conservação da biodiversidade local e global. O sistema do rio Tramandaí (SRT) apresenta uma série de lagoas costeiras rasas conectadas por canais naturais, e uma saída, via estuário de Tramandaí, para o oceano. Esse sistema é dividido em dois subsistemas, ao norte e ao sul do estuário, resultado de padrões hidrodinâmicos e da influência do vento e que definem características ambientais distintas a esses subsistemas. Um gradiente decrescente, de norte a sul, no estado trófico dessas lagoas já foi verificado. No presente estudo é testada hipótese de variabilidade espacial (lagoas e subsistemas) e temporal (estações do ano) na magnitude de variáveis abióticas e de descritores ecológicos das assembleias de peixes (composição, riqueza, diversidade, dominância) do SRT. Também é avaliada a relação entre variáveis abióticas e descritores das assembleias nesses subsistemas. É comparada a seletividade de captura de um amostrador ativo (rede de arrasto de praia) e de um amostrador passivo (redes de emalhe). Amostragens foram conduzidas de novembro de 2008 a abril de 2010 com rede de arrasto de praia e redes de emalhe, na zona litoral das lagoas Itapeva, Quadros e Malvas no subsistema norte, e nas lagoas Fortaleza, Rondinha e Barros no subsistema sul. Entre abril de 2009 e março de 2010, amostras de água foram coletadas e dez variáveis foram mensuradas em laboratório. Análises de ordenação (NMDS) mostraram clara diferença de composição, abundância numérica (CPUEn) e em biomassa (CPUEb) de espécies entre amostradores. A análises de ANOSIM e SIMPER mostraram baixa similaridade desses parâmetros entre amostradores. Houve diferença no tamanho dos peixes coletados com redes de arrasto e emalhe. Turbidez e DBO5 tiveram médias superiores no subsistema norte, enquanto que condutividade, salinidade, dureza, sólidos totais dissolvidos e transparência de Secchi no subsistema sul. Temporalmente foram verificadas diferenças de temperatura, pH, salinidade, turbidez, dureza, sólidos totais dissolvidos, oxigênio dissolvido, sólidos suspensos e profundidade, mas somente os dados de pH, condutividade, turbidez e DBO5 mostraram interação entre os fatores espaço e tempo. As assembleias das margens rasas da zona litoral foram dominadas por dez espécies, resultando em alta similaridade de composição, CPUEn e CPUEb entre os subsistemas. A riqueza de espécies variou espacial e temporalmente. Diversidade e equitabilidade espacialmente, e CPUEn e CPUEb temporalmente. As assembleias das regiões pelágicas da zona litoral foram dominadas por sete espécies, com dominância numérica das espécies L. anus e A. aff. fasciatus no subsistema norte. A NMDS mostrou similaridades maiores de composição, CPUEn e CPUEb entre amostras de um mesmo subsistema, no entanto, a ANOSIM não apresentou resultados significativos para rejeição das hipóteses nulas. CPUE n e b, diversidade e equitabilidade variaram espacialmente, enquanto a riqueza, temporalmente. A análise de correlação canônica (CCA) mostrou que temperatura, DBO5, sólidos suspensos e dureza responderam por 46% da variabilidade dos dados de abundância numérica das espécies. Os resultados sugerem que amostradores ativos e passivos reproduzem diferentes imagens da assembleia por eles amostrada, indicando que o delineamento amostral para estudos com peixes nesses ecossistemas deve contemplar tais diferenças. As diferenças ambientais dos subsistemas refletem em diferenças na qualidade da água e os resultados obtidos confirmam os pressupostos do gradiente trófico. A estrutura das assembleias de peixes foi mais variável em resposta as condições ambientais em escala espacial, enquanto que temporalmente, houve maior coerência na variabilidade dos dados. As relações das espécies com as variáveis ambientais são discutidas com base no comportamento alimentar e/ou reprodutivo das mesmas e na qualidade do habitat. Tais resultados podem ser úteis como subsídio a elaboração de estudos de manejo costeiro do SRT, sobretudo com relação aos recursos pesqueiros, e na proposição de modelos de estrutura das assembleias de peixes de lagoas costeiras subtropicais. / Coastal lakes ecosystems are crucial for conserving biodiversity both locally and globally. The river Tramandaí system (SRT) comprises a series of shallow coastal lagoons, connected by natural channels, and has an output via Tramandaí estuary into the ocean. This system is divided into two subsystems, north and south of the Tramandaí estuary, as result of hydrodynamic patterns, influence of wind and environmental characteristics that define the subsystems. A trophic gradient decreasing from north to south in those lagoons was identified. In this study is tested the hypothesis of spatial (lagoons and subsystems) and temporal (seasons) variabilities in the amplitude of abiotic variables and descriptors of the fish assemblages (species composition, richness, diversity, dominance) in the SRT. It also assessed the relationship between abiotic variables and descriptors of the fish assemblages in these subsystems. Is compared the selectivity of the active fishing (beach seining) and passive (gill netting) fishing. Sampling was conducted from November 2008 to April 2010 with beach seine and gill nets in the littoral zone of lakes Itapeva, Quadros and Malvas in north subsystem, and Fortaleza, Rondinha and Barros lakes, in south subsystem. Between April 2009 and March 2010 water samples were collected and ten variables were measured in the laboratory. Analyses of ordination (NMDS) showed clear differences in composition, numerical abundance (CPUEn) and biomass (CPUEb) of species between samplers. The analysis of similarity (ANOSIM and SIMPER) showed low similarity of these parameters between nets. There was a difference in the size of the fish caught with beach seine and gill nets. Turbidity and BOD5 averages were higher in the northern subsystem, while the conductivity, salinity, hardness, total dissolved solids and Secchi transparency in the south subsystem. Temporally were observed differences in temperature, pH, salinity, turbidity, hardness, total dissolved solids, dissolved oxygen, suspended solids and depth, but only the data for pH, conductivity, turbidity, BOD5 showed interaction between the factors space and time. The assemblages of the shallow margins of the coastal zone were dominated by ten species resulting in high similarity of composition, CPUEn and CPUEb between subsystems. Species richness varied spatially and temporally, while diversity and evenness only spatially and CPUEn and CPUEb only temporally. The assemblages of the pelagic regions of the coastal zone were dominated by seven species with numerical dominance of L. anus and A. aff. fasciatus in north subsystem. The NMDS showed greatest similarity in composition, CPUEn and CPUEb between samples of the same subsystem, the ANOSIM however, showed no significant results for rejection of the null hypothesis. CPUE n and b, diversity and equitability varied between lakes and subsystems, while the richness between seasons. The canonical correlation analysis (CCA) showed that four variables (temperature, BOD, suspended solids and hardness) account for 46% of data variability of species abundance. Samples of the north subsystem were directly influenced by temperature, BOD and suspended solids while the south subsystem by the hardness. The results suggest that active and passive samplers reproduce different images of the assemblage sampled and indicate that the sampling design for studies of these ecosystems should include such differences. The environmental differences in subsystems reflect in water quality differences and the results confirm the assumptions of a trophic gradient decreasing from north to south in the SRT. The structure of the fish assemblages was more variable in response to environmental conditions in spatial scale between subsystems, while there was greater consistency in the temporal variability of the data. The relationships between the species and environmental variables are discussed based on the feeding behavior and / or reproduction of the same and by habitat quality. These results may be useful as an aid to preparing studies of coastal management of SRT, especially with respect to fisheries, and in proposing models of the structure of the fish assemblages of subtropical coastal lagoons.

Made available in DSpace on 2014-07-29T15:10:32Z (GMT). No. of bitstreams: 1 Tese Tatiana S Fiuza.pdf: 214501 bytes, checksum: abb8f10f906147d3c8811901c4bb08ab (MD5) Previous issue date: 2009-01-22 / The purpose of this work is to perform the pharmacognostic studies of the species Hyptidendron canum (Pohl ex Benth.) Harley (Lamiaceae) and Eugenia uniflora L. (Myrtaceae), investigate the population variability of the constituents of the essential oil from H. canum leaves and inflorescences, and assess the bioactivity of the crude ethanol extracts and fractions from leaves of this plants against microorganisms (bacteria and the fungus Candida albicans) and on Oreochromis niloticus Linnaeus. For the variability study of the H. canum essential oil, samples obtained from leaves and inflorescences from Hidrolândia, Silvânia, Bela Vista and Goiânia cities were analyzed by gas chromatography and gas chromatography with mass spectrometry. The anatomic analysis and the phytochemical screening of the leaves from the two species were performed using conventional techniques. The antimicrobial activity was assessed with Gram-positive and Gram-negative bacteria and with the Candida albicans fungus using the well diffusion test and the agar dilution method to determine the minimal inhibitory concentration (MIC). The biological activities of the crude ethanol extract and ethyl acetate, hexanic and chloroformic fractions of the leaves from the two species were tested in O. niloticus fish hepatopancreas and gill. The H. canum essential oils analysis indicated high chemovariability in the oils from different locations. The phytochemical screening and the thin layer chromatography (TLC) analysis of the H. canum leaves evidenced the presence of flavonoids, saponins, terpenes and lignans, while the E. uniflora leaves evidenced the presence of tannins, steroids, triterpenes, anthraquinonic heterosides, saponinic and flavonoids. As for the antimicrobial activity testing, the crude ethanol extracts from both species presented antimicrobial activity against all the microorganisms tested and the E. uniflora ethyl acetate fraction presented satisfactory activity against resistant Pseudomonas aeruginosa. The H. canum crude extract and fractions presented vasoactive activity in the hepatopancreas and gill of the tilapias, causing varying degrees of vasodilation and vascular congestion. An apparent proliferation of blood capillaries was detected in the hepatopancreas of the fish that ingested the hexanic fraction. The E. uniflora crude extract and the ethyl acetate, chloroform and hexanic fractions caused vasodilation, vascular congestion and tissue alterations in the O. niloticus hepatopancreas and gills / O presente trabalho teve por objetivo realizae o estudo farmacognóstico das espécies Hyptidendron canum (Pohl ex Benth.) Harley (Lamiaceae) e Eugenia uniflora L. (Myrtaceae), investigar a variabilidade populacional dos constituintes do óleo essencial das folhas e inflorescências da H. canum e avaliar a bioatividade dos extratos etanólicos brutos e das frações das folhas das referidas plantas contra icrorganismos (bactérias e fungo) e em Oreochromis niloticus Linnaeus. Para o estudo da variabilidade do óleo essencial da H. canum, as folhas e inflorescências foram coletadas nos municípos de Hidrolândia, de Silvânia, de Bela Vista e de Goiânia e seus óleos essenciais foram analisados por cromatografia gasosa e cromatografia gasosa acoplada a espectrometria de massa. A análise anatômica e a prospecção fitoquímica das folhas das duas espécies foram realizadas utilizando as técnicas convencionais. A atividade antimicrobiana foi avaliada com bactérias Gram-positivas e Gramnegativas e com o fungo Candida albicans, usando o teste de difusão em poço e o método de diluição em ágar, para determinar a concentração inibitória mínima (CIM). As atividades biológicas do extrato etanólico bruto e das frações acetato de etila, hexânica e clorofórmica das folhas das duas espécies foram avaliadas no hepatopâncreas e brânquias do peixe O. niloticus L. A análise dos óleos essenciais da H. canum indicou elevada quimiovariabilidade nos óleos dos diferentes locais. A triagem fitoquímica e a cromatografia em camada delgada (CCD) das folhas da H. canum evidenciaram a presença de flavonóides, saponinas, terpenos e lignanas e das folhas da E. uniflora, a presença de taninos, esteróides, triterpenos, heterosídeos antraquinônicos, saponínicos e flavonóides. Na avaliação da atividade antimicrobiana, observou-se que os extratos etanólicos brutos das duas espécies demonstraram atividade antimicrobiana contra todos os microrganismos testados, e a fração acetato de etila da E. uniflora apresentou boa atividade contra Pseudomonas aeruginosa resistentes aos antibióticos convencionais. O extrato bruto e as frações da H. canum apresentaram atividade vasoativa no hepatopâncreas e brânquias das tilápias, promovendo, em maior ou menor grau, vasodilatação e congestão vascular. Detectou-se ainda aparente proliferação dos capilares sanguíneos no hepatopâncreas dos peixes tratados com a fração hexânica. Verificou-se que tanto o extrato bruto, quanto as frações acetato de etila, clorofórmica e hexânica da E. uniflora promoveram, no hepatopâncreas e nas brânquias de O. niloticus, vasodilatação, congestão vascular e alterações teciduais

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This Thesis is a proposal for a prototypical hillside housing community in Los Angeles, California. As a prototype it is responsible for setting an architectural precedent. In this effort, the Thesis continues with focus on issues of construction methodology, urban planning, and land use relationships concerning the present city. Being clear and uncomplicated is the driving force of this architectural process. On the horizon is the 21st Century. Architecture has become increasingly convoluted rather than enlightened. Here, I have focused my attentions on developing a technologically based, material-driven, compassionate solution to answer the issue of housing on the hillsides of Los Angeles. I have realized a clear system of building using uncomplicated technology and material. However, as demonstrated, this system of building provides only an envelope for space definition. It becomes the architectural precedent, a canvas, through which the inhabitant can define his existence. Enlightened limitations. / Master of Architecture

(Oberflächen-) Gewässer weltweit sind mit geringen Mengen (ng/L bis wenige µg/L) humaner Pharmazeutika belastet. Diclofenac (DCF; nicht-steroidal, entzündungshemmend) und Metoprolol (MTP; ß-Blocker) gehören entsprechend ihres hohen Verbrauchs zu den am häufigsten gefundenen Substanzen. Deren biologische Aktivität ist nicht auf den Menschen beschränkt. Gut konservierte Enzyme innerhalb der Vertebraten legen Auswirkungen auf Nicht-Zielorganismen wie Fische nahe, die bisher in Langzeituntersuchungen mit umweltrelevanten Konzentrationen unzureichend untersucht wurden. In der vorliegenden Arbeit wurden die physiologischen Effekte von DCF und MTP auf die Nil-Tilapie (Oreochromis niloticus), einem der wichtigsten Aquakulturfische weltweit, untersucht. In vitro konnte anhand primärer Hepatozyten gezeigt werden, dass bereits umweltrelevante Konzentrationen von DCF zu einer erhöhten Genexpression verschiedener Schlüsselenzyme der Detoxifizierung führten. Nach MTP-Exposition waren die Veränderungen weniger eindeutig. Beide Substanzen induzierten die Vitellogenin Genexpression, nur DCF jedoch bereits in umweltrelevanter Konzentration. In vivo wurden in zwei Langzeit-Expositionsversuchen die physiologischen Effekte vom befruchteten Ei bis 80 Tage nach Schlupf in O. niloticus untersucht. Beide Substanzen hatte keinen Einfluss auf Schlupferfolg und Überleben, das Wachstum war nach 80 Tagen nach Schlupf leicht reduziert. Die deutlichsten Auswirkungen waren histopathologische Veränderungen der Kiemen, veränderte Genexpressionen der Gonadotropine und eine erhöhte Expression von Vitellogenin. Die Ergebnisse legen eine stärkere östrogene Aktivität von DCF im Vergleich zu MTP nahe. Zusammenfassend sind die Bedenken gegenüber den Einzelsubstanzen eher gering, negative Auswirkungen auf die Reproduktion und sich verstärkende Effekte bei zeitgleicher Exposition gegenüber DCF und MTP lassen sich jedoch nicht ausschließen und sollten im Weiteren untersucht werden. / Surface waters worldwide are contaminated with low levels (ng/L up to few µg/L) of human pharmaceuticals. Diclofenac (DCF; non-steroidal, anti-inflammatory) and metoprolol (MTP; ß-blocker) are highly consumed and therefore commonly detected. Their biological activity is not restricted to humans. Well conserved enzymes within the vertebrates suggest effects on non-target organisms such as fish, poorly studied in long-term exposure experiments using environmentally relevant concentrations. In the presented work, physiological effects of DCF and MTP on the Nile tilapia (Oreochromis niloticus), an important aquaculture fish species, were studied. Using primary hepatocytes, it was shown in vitro that environmentally relevant concentrations of DCF increased the gene expression of different key enzymes of the detoxification, while MTP exposure had a less clear effect. Both substances induced vitellogenin gene expression, but only after DCF exposure this was significantly elevated already at the environmentally relevant concentration. In vivo, two long-term exposure studies on the physiological effects from the fertilized egg until 80 days post-hatch were evaluated. Both substances did not affect hatching success and survival, while growth was slightly reduced after 80 days post-hatch. Histopathological alterations of the gills, changed gene expression patterns of the gonadotropins and induced vitellogenin gene expression were the most dominant findings. The results indicate a stronger estrogenic mode of action of DCF compared to MTP. Overall, the risk due to a single substance exposure seems to be relatively low but adverse effects on reproduction and additive effects during simultaneous exposure to DCF and MTP cannot be excluded and should be investigated further.

Ce projet de mémoire entreprend de montrer dans quelles conditions artistiques et sociales ont évolués cinq peintres canadiens à Paris à la fin du XIXe siècle. Les artistes à l'origine de la décoration de la chapelle Sacré-Coeur de l'église Notre-Dame de Montréal; Henri Beau, Joseph Franchère, Charles Gill, Ludger Larose ainsi que Joseph Saint-Charles, se présentent ici, comme un prétexte à l'étude du parcours emprunté par nombreux peintres canadiens à Paris à cette époque. Le choix de la période d'étude est déterminé par le début de leur séjour en France et par la fin du projet de décoration de la chapelle (1887-1895). Dans un premier temps, la recherche dresse un portrait du contexte de formation dans lequel ils ont progressé. À ce propos, l'École Nationale Spéciale des Beaux-Arts, l'Académie Julian et Colarossi sont les principales institutions fréquentées par les artistes. Dans un deuxième temps, cette étude établit quelles étaient leurs conditions de vie et occupations sociales à Paris. Pour ce faire, elle définit leur situation économique par le type d'habitation dans lequel ils vivaient et leur emplacement. Quant à leur vie sociale comme étrangers, elle est reconstituée à partir des lieux et des personnes qu'ils côtoyaient. Dans un dernier temps, ce mémoire entreprend d'illustrer dans quelle mesure leur passage dans la capitale mondiale de l'art a influencé leur carrière artistique au Canada. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Henri Beau, Joseph-Charles Franchère, Charles Gill, Ludger Larose, Joseph Saint-Charles, Académies, Paris, Chapelle du Sacré-Coeur, Montréal.

Made available in DSpace on 2016-06-02T19:30:11Z (GMT). No. of bitstreams: 1 TeseRDO.pdf: 756445 bytes, checksum: dd46098f781f2c54d8f4d7f9d1c6bb92 (MD5) Previous issue date: 2003-04-25 / Universidade Federal de Sao Carlos / Tropical fish generally inhabit environments with high temperatures and low dissolved oxygen. Along the evolutionary process several species developed mechanisms of air-breathing in order to compensate the oxygen demands caused by the aquatic hypoxia. These mechanisms required anatomical, physiological and biochemical adaptations. Studies on the effects of hypoxia and temperature changes on fish involve the comprehension of the cardio-respiratory mechanisms of compensation. The present study was addressed to determine the cardio-respiratory and air-breathing responses of jeju, Hoplerythrinus unitaeniatus, which utilize the swimming bladder as an organ for accessory respiration in the air, submitted to gradual hypoxia after acclimation to 15, 20, 25 and 30oC. The oxygen uptake ( &VO2 ), gill ventilation ( G V& ) breathing frequency (fR), ventilation volume (VT) and the O2 extraction from the ventilatory current (EO2) were obtained for specimens of jeju (Wt = 209,7 ± 5 g) by flow-trough respirometry. The air-breathing frequency (fRA) and time spent in air-breathing (TRA) were determined by means of an experimental chamber specially constructed for this purpose. Independently of the acclimation temperature, jeju responded to hypoxia as an oxyregulator, i. e., the species was able to keep constant &VO2 in response to graded hypoxia until reach a critical oxygen tension (PcO2). The mean &VO2 values at each acclimation temperature, before reaching the PcO2, were: 47 ± 0,8 mlO2.kg-1h-1 (15°C), 82 ± 0,3 mlO2.kg-1h-1 (20°C), 104 ± 2,6 mlO2.kg-1h-1 (25°C) and 112 mlO2.kg-1h-1 (30°C). The PcO2 for each acclimation temperature were 28, 33, 41 e 52 mmHg, respectively. The increased reductions on PcO2 as acclimation temperatures rose from 15 to 30oC showed that this species presents partial compensation (or type 3 compensation) to temperature increases. Jeju increased the G V& to compensate the graded hypoxia due to higher increments on VT than in fR. This kind of compensation, however, was not enough to keep a constant EO2, which decreased gradually in response to graded hypoxia in all acclimation temperature. At 25 and 30°C the fH were significantly higher than at 15 and 20oC. Hypoxic bradicardia was not recorded at 15 and 20oC and at 25 and 30°C it only occurred below the PcO2. The different PcO2 were also the threshold for the development of accessory air-breathing in all acclimation temperatures. Increases in both fRA and TRA were inversely proportional to the water PO2 reductions and directly proportional to the acclimation temperature. / Peixes de água doce tropical vivem em ambientes de altas temperaturas e baixas concentrações de O2. Isto resultou, ao longo do processo evolutivo, na necessidade da tomada do ar atmosférico em várias espécies de peixes, a fim de compensar seus requerimentos metabólicos, o que requereu modificações anatômicas, fisiológicas e bioquímicas. Estudos sobre o efeito da hipóxia e da variação da temperatura ambiental nos peixes devem envolver o conhecimento dos mecanismos de compensação cardiorespiratória. Assim, o objetivo deste estudo foi determinar as respostas cardiorespiratórios e da respiração aérea de jeju (Hoplerythrinus unitaeniatus), que utiliza a bexiga natatória como órgão acessório de troca gasosa, após período de aclimatação nas temperaturas de 15, 20, 25 e 30°C e submetido à hipóxia gradual. As medidas do consumo de O2 ( &VO2 ), ventilação branquial ( G V& ), freqüência respiratória (fR), volume ventilatório (VT) e extração de O2 da corrente ventilatória (EO2) foram obtidas de exemplares de jeju (Wt = 209,7 ± 5 g) por meio de respirometria de fluxo constante. A freqüência (fRA) e o tempo da respiração aérea (TRA) também foram determinados utilizando-se de uma câmara especialmente desenvolvida para esta finalidade. Independentemente da temperatura de aclimatação, H. unitaeniatus comportou-se como um oxi-regulador, mantendo uma &VO2 constante por amplos intervalos de reduções de O2 até atingir a tensão crítica de O2 (PcO2). Nas diferentes temperaturas a &VO2 foi de 47 ± 0,8 mlO2.kg-1h-1 a 15°C, 82 ± 0,3 mlO2.kg-1h-1 a 20°C, 104 ± 2,6 mlO2.kg-1h-1 a 25°C e 112 mlO2.kg-1h-1 a 30°C. As PcO2 nas respectivas temperaturas foram de 28, 33, 41 e 52 mmHg. A redução crescente das PcO2 mostrou que esta espécie apresenta uma compensação parcial ou do tipo 3 aos aumentos crescentes na temperaturas de aclimatação. O jeju aumentou a G V& em resposta à hipóxia gradual valendo-se de maiores incrementos no VT do que na fR. Entretanto, este tipo de compensação não foi suficiente para manter uma constante EO2, a qual decresceu gradualmente em função da hipóxia. A fH a 25 e 30°C foi significativamente mais elevada do que a 15 e 20°C. A bradicardia hipóxica só foi registrada nas temperaturas de 25 e 30°C e somente ocorreu em tensão abaixo das respectivas PcO2. As PcO2 foram o limiar para o início da respiração aérea acessória em todas as temperaturas estudadas. Os aumentos na fRA, assim como da TRA foram inversamente proporcionais às reduções da PO2 da água e diretamente proporcionais às temperaturas de aclimatação.

Fish encounter daily cycles of hypoxia in the wild, but the physiological strategies for coping with repeated cycles of normoxia and hypoxia (intermittent hypoxia) are poorly understood. Contrastingly, the physiological strategies for coping with continuous (constant) exposure to hypoxia have been studied extensively in fish. The main objective of this thesis was to understand how Fundulus killifish cope with a diurnal cycle of intermittent hypoxia, an ecologically relevant pattern of aquatic hypoxia in the natural environment. To do this, I characterized the effects of intermittent hypoxia on hypoxia tolerance, oxygen transport, metabolism, and the oxidative stress defense system of killifish, and compared these effects to fish exposed to normoxia, a single cycle of hypoxia-normoxia, and constant hypoxia. Specifically, I studied the following topics: (i) how acclimation to intermittent hypoxia modifies hypoxia tolerance, and the hypoxia acclimation response of Fundulus heteroclitus (Chapter 2), (ii) metabolic adjustments occurring during a hypoxia-reoxygenation cycle (Chapter 3), (iii) how acclimation to intermittent hypoxia alters O2 transport capacity and maximal aerobic metabolic rate (Chapter 4), (iv) the effects of hypoxia and reoxygenation on reactive oxygen species and oxidative stress (Chapter 5), and (v) variation in hypoxia tolerance and in the hypoxia acclimation responses across Fundulus fishes (Chapter 6). Killifish rely on a unique and effective physiological strategy to cope with intermittent hypoxia, and that this strategy is distinct from both the response to a single bout of acute hypoxia-reoxygenation (12 h hypoxia followed by 6 h reoxygenation) and to chronic exposure to constant hypoxia (24 h hypoxia per day for 28 d). Key features of the acclimation response to intermittent hypoxia include (i) maintenance of resting O2 consumption rate in hypoxia followed by a substantial increase in O2 consumption rate during recovery in normoxia, (ii) reversible increases in blood O2 carrying capacity during hypoxia bouts, (iii) minimal recruitment of anaerobic metabolism during hypoxia bouts, and (iv) protection of tissues from oxidative damage despite alterations in the homeostasis of reactive oxygen species and cellular redox status. Of these features, (i) is unique to intermittent hypoxia, (ii) also occurs in fish exposed to acute hypoxia-reoxygenation, and (iii) and (iv) are observed in both fish acclimated to intermittent hypoxia as well as those acclimated to constant hypoxia. This is the most extensive investigation to date on how fish cope with the energetic and oxidative stress challenges of intermittent hypoxia, and how these responses differ from constant hypoxia. This thesis adds substantial insight into the general mechanisms by which animals can respond to an ecologically important but poorly understood feature of the aquatic environment. / Dissertation / Doctor of Philosophy (PhD) / Oxygen levels in the aquatic environment are dynamic. Many fishes routinely encounter changes in oxygen content in their environment. However, we have very little understanding of how cycles between periods of low oxygen (hypoxia) and periods of high oxygen (normoxia) affect the physiology of fish. This thesis investigated how Fundulus killifish cope with daily cycles between hypoxia and normoxia (intermittent hypoxia) by modifying oxygen transport, metabolism, and oxidative stress defense systems. I found that killifish rely on a unique and effective physiological strategy to cope with intermittent hypoxia, and that this strategy is distinct from how they respond to a single bout of hypoxia (followed by normoxia) and to a constant pattern of only hypoxia. This is the most extensive investigation to date on how fish respond to the challenges of intermittent hypoxia, an understudied but ecologically important type of aquatic hypoxia.

In dieser Arbeit wurden die Morpho-Physiologie und das Verhalten zweier Arten Afrikanischer schwach elektrischer Fische, Marcusenius victoriae und Petrocephalus degeni, im Labor und in einem ihrer natürlichen Habitate im Lwamunda Sumpf in Uganda untersucht. Die zwei Hauptziele dieser Arbeit waren (i) tageszeitabhängige Verhaltensrhythmen (Aktivität, Habitatnutzung) im Labor und im Freiland zu untersuchen und (ii) die Ausprägung und Plastizität der morpho-physiologischen Merkmale von P. degeni zu untersuchen, die ihnen erlauben bei natürlich vorkommender, geringer Sauerstoffverfügbarkeit (Hypoxie) zu überleben. Tageszeitabhängige Verhaltensrhythmen beider Arten wurden im Labor über 42 Stunden und im natürlichen Habitat dieser Fische für sechs Tage erfasst. In den Laborversuchen verbrachten beide Arten tagsüber annähernd 100% der Zeit in einem bereitgestellten Versteck und schwammen nachts heraus um aktiv ihre Umwelt zu erkunden. Im Habitat wurden die meisten Fische in strukturell komplexen Habitaten unter schwimmenden Pflanzen detektiert. Nachts schwammen die Fische aktiv in die offenen und ungeschützten Bereiche der Lagune, vermutlich um nach Futter zu suchen und zu interagieren. Die Begleitende in-situ Messung der Sauerstoffverfügbarkeit zeigte, dass beide Arten präsent und vermutlich sogar am aktivsten waren während Phasen extremer nächtlicher Hypoxie. Zur Untersuchung der respiratorischen Merkmale von P. degeni wurden Respirometrieversuche mit hypoxie-akklimatisierten Tieren durchgeführt, Hämoglobin- und Laktatkonzentration im Blut gemessen, und morphologische Parameter an den ersten beiden Kiemenbögen erfasst. Die Fische zeigten niedrige Sauerstoffverbrauchsraten, welche sie bis zu einem sehr niedrigem äußeren Sauerstoffpartialdruck aufrechterhielten. Zusätzlich zeigten sie hohe Hämoglobin- und Laktatkonzentrationen im Blut. Bis zu 75 Tage Normoxie-Akklimatisierung führte zu reduzierter Hämoglobinkonzentration und kürzeren Kiemenfilamenten. / In this thesis, I investigated the morpho-physiology and behavior of two species of African mormyrid weakly electric fish, Marcusenius victoriae and Petrocephalus degeni, in the laboratory and in one of their natural habitats, the Lwamunda Swamp in Uganda. The two main objectives of this work were to (i) observe behavioral rhythms and habitat use patterns of both species under natural and laboratory conditions, and (ii) assess expression and plasticity of morpho-physiological traits that might enable P. degeni to survive naturally occurring low oxygen conditions (hypoxia). Behavioral rhythms were recorded in the laboratory over 42 hours and in the habitat on six sampling days. In the laboratory, both species spent close to 100% of the time in their shelter during the day and actively explore their environment at night. In the swamp lagoon, fish were most often encountered in structurally complex habitats under floating vegetation and ventured into open and unsheltered areas of the lagoon at night, presumably to forage and interact. Concomitant in-situ oxygen measurements revealed that these fish were present, and presumably most active during periods of extreme nocturnal hypoxia in their swamp habitat. To investigate respiratory traits of swamp-dwelling P. degeni, I conducted respirometry experiments and measured blood lactate and hemoglobin and gill morphometrics on the first two gill arches. Fish showed low routine oxygen consumption rates, which they maintained until a very low ambient oxygen partial pressure was reached. Additionally, they had high concentrations of hemoglobin and lactate in their blood. Up to 75 days of normoxia exposure reduced blood hemoglobin and gill filament length.