The daily oxygen consumption (VO2) pattern, the effects of varying ambient temperatures, season and mass on the resting oxygen consumption (RVO2) of Chersina angulata of the Eastern Cape were investigated. The RVO2 was measured using flow-through respirometry and specific resting oxygen consumption (sRVO2) calculated. To determine the daily pattern in the VO2 of C. angulata, the tortoises were acclimated in an environmentally controlled room (ECR) to an ambient temperature of 26 ± 1°C and a light regime of 14 hours of light and 10 hours of darkness (14L:10D) for at least a week prior to the RVO2 measurements. The RVO2 was measured at a constant temperature of 26 ± 1°C, and at three different light regimes, namely: 14L:10D, constant darkness (DD) and constant light (LL). There were no significant effects of mass or gender on the sRVO2 of the tortoises used. Rhythms in the sRVO2 were detected under all three light regimes. The amplitudes of the rhythm were largest at 14L:10D, followed by DD and smallest at LL regime. The persistence of the rhythmic pattern under constant conditions suggests the existence of an endogenous circadian rhythm in the sRVO2 for adult C. angulata. To test for the effect of ambient temperature on the sRVO2 of adult C. angulata, the tortoises were acclimated to 22 ± 1°C and a 14L:10D light regime prior to the RVO2 measurements. RVO2 was measured at eight experimental temperatures; 14°C, 18°C, 22°C, 26°C, 30°C, 35°C, 38°C and 40°C. The sRVO2 was not influenced by gender and increased with experimental temperatures, but this did not happen consistently over the whole range of temperatures tested. A plateau, possibly a thermal preferendum zone, was detected within the temperature range of 26 - 38°C. Determination of seasonal effect on the sRVO2 of adult C. angulata was accomplished by acclimating tortoises to standard summer and winter conditions. Seasonal effects were tested in the appropriate seasons. Winter experiments were conducted in winter and summer experiments conducted in summer. The RVO2 was measured at experimental temperature 14°C, 18°C and 22°C. In addition RVO2 of iv winter-acclimated tortoises was also measured at 10°C. The sRVO2 increased significantly with increasing temperature within the temperature range tested. No distinct pattern was observed in the seasonal acclimation of adult C. angulata. The metabolic rate-temperature curves of the summer and the winter-acclimated tortoises cross each other. Season and temperature had no significant effects on the mass-scaling exponent of the sRVO2. The exponent ranged from 0.48 to 0.73 within the temperature range of 22 - 38°C. Below and above this temperature range, the exponent ranged from 1.47 to 1.67. An inverse relationship was observed between sRVO2 and body mass over the temperature range of 22 - 38°C. At 14°C and 18°C, sRVO2 increased with body mass, while at 10°C and at 40°C the slope was 1.01.

Among the basal bony fishes, the American paddlefish (Polyodon spathula) has a unique respiratory strategy of ram-ventilation. However, despite the increasing problems caused by hypoxia in natural habitats occupied by this species, little information exists about their response to hypoxia. Four studies were conducted to examine the physiological and biochemical responses of juvenile paddlefish (150-181 g) to acute and chronic hypoxia. Acute hypoxia tolerance, aerobic metabolic rates and swimming capabilities of paddlefish in an intermittent respirometer or swim flume were evaluated under normoxic (partial pressures of oxygen [pO2] =140 mm Hg) and hypoxic (pO2 =62 mm Hg) conditions at 18 °C and 26 °C. Additionally, blood oxygen transport, blood acid-base balance and metabolic stress were evaluated in paddlefish independently exposed to 4 different pO2s: normoxia =148 mm Hg, mild hypoxia =89 mm Hg, moderate hypoxia =59 mm Hg and extreme hypoxia =36 mm Hg, at 21°C. Blood samples were collected from paddlefish after they had been exposed to treatment pO2’s for 0.25, 2, 6, 24 and 72 hours, and analyzed for hematocrit, pO2, total oxygen content, pCO2, pH, hemoglobin, Na+, K+, Ca2+, Cl-, glucose, lactate, etc. A third study used 1-D and 2-D J-resolved 1H NMR to analyze metabolite changes in muscle tissue of paddlefish exposed to normoxia (148 mm Hg), or acute (0.25 h) or chronic (72 h) moderate hypoxia (59 mm Hg). The last study examined the effect of moderate hypoxia (pO2: 59 mm Hg) and subsequent recovery in normoxia (pO2: 148 mm Hg) on plasma cortisol, blood oxygen transport, blood acid-base balance, metabolic, ion-osmoregulation and enzyme parameters in paddlefish. The results indicate that paddlefish have a critical pO2 of 74 mm Hg at 18 °C and 89 mm Hg at 26 °C and a lethal oxygen threshold of ~2 mg/ L. Sensitive to moderate hypoxia, death occured after 3-8 hours of extreme hypoxia. Paddlefish have reduced capacity for metabolic depression and, as a result, survival in hypoxia is limited due to a reduction in both aerobic and anaerobic (glycogen and glucose) energy stores as well as the accumulations of toxic H+ and lactate. Nonetheless recovery is possible.

Brief periods of skeletal muscle ischemia (ischemic pre-conditioning) alter cellular metabolism in a way that confers protection over subsequent ischemic episodes. The mechanisms behind this effect have been studied indirectly through assays for the byproducts of ATP synthesis and in vitro studies of cellular signaling cascades and ROS generation. There have been no direct, in vivo assessments of the changes in respiration during reperfusion. We employed phosphorescence quenching microscopy in conjunction with a flow-arrest technique to assess the influences of external, pressure-induced 1- to 10-min focal ischemia on interstitial oxygenation (PISFO2) and the consumption of oxygen (VO2) in spinotrapezius muscles of Sprague-Dawley rats. During reperfusion following an ischemic period VO2 was measured by the rate of PISFO2 decline during brief, serial flow-arrest compressions. Our tests of this intermittent compression technique indicate that 5 s of flow-arrest followed by 15 s of flow restoration allow measurement of VO2 without compromising baseline or reperfusion recovery of PISFO2. There was a steady rise in VO2 during early reperfusion which was correlated with increasing ischemic durations. Treatment with cyanide confirmed that at least some of this increase was due to an upregulation of cytochrome c oxidase activity. Nitric oxide (NO) suppressed VO2 during rest and reperfusion, while L-NAME did not influence respiration under normoxic conditions. L-NAME produced a significant rise in VO2 under hypoxic conditions following 10 minutes of ischemia, indicating a greater role of NO in the regulation of respiration during low PISFO2 conditions. We conclude that physiological levels of NO regulate mitochondrial respiration during hypoxia and confirm that pharmacological elevation of [NO] reduces VO2 in a manner consistent with the ischemic pre-conditioning effect.

Title of master thesis Physiological response and physical activity during climbing wall in school age children Work objectives Determinaton of specific oxygen uptake during climbing in the climbing wall in children. Methods The study involved 10 boys and 9 girls. Their climbing ability was in range 4 to 5+ degree of UIAA (Union Internationale des Associations d'Alpinisme). Maximal oxygen consumption was measured on climbing wall. The climbers climbed two routes, the first vertical profile (90ř) and second overhanging profile (110˚). The participants climbed the wall with a self-selected speed. They climbed the route twice to steady state of physiological response during climbing and to simulate real average wall (15 m). To make conditions equal, everybody had 30 s to get down and start climbing again. Results The girls achieved average of specific oxygen consumption VO2peak 37,1 ± 4,8 ml·kg- 1 ·min-1 in the vertical profile and in the overhanging profile was 40,6 ± 11,5 ml·kg- 1 ·min-1 . The boys achieved slightly higher average of specific oxygen consumption in both profile 39,1 ± 4,8 ml·kg-1 ·min-1 in the vertical profile and 42,1 ± 2,6 ml·kg-1 ·min-1 in the overhanging profile. The girls had average peak heart rate 179 ± 10 beats·min-1 in the vertical profile and boys 170 ± 14 beats·min-1 ....

Esta dissertação possui o objetivo geral de analisar desempenho, parâmetros antropométricos, biomecânicos, fisiológicos e nutricionais de nadadores máster competitivos em diferentes faixas etárias. Participaram, de uma ou mais fases da pesquisa, 23 atletas máster de natação do sexo masculino, amadores, divididos por percentil de idade (P) em três grupos etários distintos. Os atletas foram avaliados quanto à antropometria e composição corporal; o desempenho, o pico de consumo de oxigênio (VO2pico) e os parâmetros biomecânicos (frequência de braçada, distância por ciclo de braçada, velocidade de nado e índice de nado) foram avaliados em um teste de 200 m nado crawl (T200), sob máxima intensidade. Parâmetros fisiológicos (consumo máximo de oxigênio - VO2max, concentração de lactato sanguínea, frequência cardíaca) e psicofisiológicos (percepção subjetiva ao esforço) foram obtidos de um teste progressivo composto por n repetições de 200 m nado crawl. Os parâmetros nutricionais foram obtidos a partir de registro alimentar de sete dias. Os dados, entre as faixas etárias, foram comparados por meio de estatística inferencial e calculados os tamanhos de efeito. O desempenho no T200 decai com o a idade, e apresenta correlação com VO2pico e variáveis biomecânicas. VO2max possui grande variabilidade entre os grupos etários, sendo influenciado por outros fatores além da idade. Ademais, nadadores máster de diferentes faixas etárias são muito similares quanto à composição corporal, ingestão e gasto energético. / The general aim of this master thesis investigation was to analyze performance and anthropometric, biomechanics, physiologic, and nutritional parameters of master swimmers in different age groups. Twenty-three male masters swimmers had participated of one or more research stages, divided into three groups accordantly to age percentile. Athletes were evaluated for anthropometry and body composition; performance, peak oxygen consumption (VO2peak) and biomechanics variables (stroke rate, stroke length, swimming speed and swimming index) were obtained from a race-pace 200 m front crawl swimming test (T200). Physiological data (maximum oxygen consumption - VO2max, blood lactate concentration and heart rate) and psychophysiological (rate of perceived exertion) were obtained from a n x 200 m progressive front crawl swimming test. Seven days food record was used to obtain nutritional variables. Data between age groups were compared using inferential statistics and effects size were calculated. T200 performance decreases with age and presents correlation with VO2peak and biomechanics variables. VO2max has high variability among groups, being influenced by other factors besides age. In addition, masters swimmers age group are similar in terms of nutrition, body composition, food intake and energy expenditure.

Gu Jia-Shi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 117-148). / Abstracts in English and Chinese. / Title --- p.i / Abstract (English) --- p.iii / Abstract (Chinese) --- p.iv / Acknowledgments --- p.v / Statement of Originality --- p.vi / List of Abbreviations --- p.viii / List of Figures --- p.xi / List of Tables --- p.xiii / Table of Contents --- p.xiv / Chapter Section One : --- Introduction & Literature Review / Introduction & Objective --- p.2 / Introduction / Objective of the present study / Chapter Chapter. 1 --- A Review of Chronic lung disease (CLD) --- p.6 / Chapter 1. --- BPD 226}0ؤ an example of CLD / Chapter 2. --- Pathological change & Clinical presentation / Chapter 3. --- Clinical sequel of CLD infants / Chapter 3.1 --- O2 consumption of CLD infants / Chapter 3.1-1 --- Oxygen consumption / Chapter 3.1-2 --- Oxygen transportation / Chapter 3.1-2a --- Dissolved O2 / Chapter 3.1-2b --- Haemoglobin / Chapter 3.2 --- Energy expenditure of CLD infants / Chapter 3.3 --- Growth rate of CLD infants / Chapter 4. --- Treatment & Management of CLD infants / Chapter 4.1 --- Diuretics / Chapter 4.2 --- Bronchodilators / Chapter 4.3 --- Corticosteroids / Chapter 5. --- "Interpretations of the observed phenomena, why does CLD impair growth?" / Chapter 5.1 --- The traditional view / Chapter 5.2 --- Disagreement with the traditional view / Chapter Chapter 2 --- Measurement of oxygen consumption --- p.20 / Chapter 1. --- Invasive measurement of VO2 / Chapter 1.1 --- Cardiac output / Chapter 1.2 --- Fick method / Chapter 1.3 --- Advantages and Disadvantages of Fick method in estimating VO2 / Chapter 1.4 --- Measurement of cardiac output by thermodilution / Chapter 1.4-1 --- Advantages and Disadvantages of Thermodilution Method / Chapter 2. --- Non-invasive measurement of VO2 / Chapter 2.1 --- Metabolic analyzer---DeltatraćёØII / Chapter 2.2 --- Paramagnetic sensor / Chapter 3. --- Measured and calculated oxygen consumption / Chapter 3.1 --- Difference between mVO2 and cVO2 / Chapter 4. --- Summary / Chapter Chapter 3 --- Hypothesis --- p.34 / Chapter 1. --- Possible explanations for the difference between mV02 & cV02 / Chapter 1.1 --- Measurement variability and Mathematical error / Chapter 1.2 --- Oxygen consumption of the lung / Chapter 1.3 --- VO2pul with lung damage / Chapter 1.4 --- "Neutrophils, Macrophages and oxygen consumption" / Chapter 2. --- Hypothesis / Chapter Section Two : --- Methods & Materials / Chapter Chapter 1 --- Animal Model --- p.41 / Chapter Chapter 2. --- Materials --- p.43 / Chapter 1. --- Animals / Chapter 2. --- Chemicals used for inducing lung damage / Chapter 2.1 --- Acute damage group / Chapter 2.1-1 --- N-nitroso-N-methylurethane (NNNMU) / Chapter 2.1-2 --- Administrations to rabbits / Chapter 2.2 --- Chronic damage group / Chapter 2.2-1 --- Bleomycin (BLM) / Chapter 2.2-2 --- Pulmonary toxicity of Bleomycin / Chapter 2.2-3 --- Administration to animals / Chapter Chapter 3 --- Instruments --- p.50 / Chapter 1. --- Measurement of VO2 and VCO2 226}0ؤDeltatracIÍёØ Metabolic analzyer / Measurement of cardiac outpu´tؤCardiomax II model85 / Chapter Chapter 4 --- Methods --- p.58 / Chapter 1. --- N-nitroso-N-methylurethane (NNNMU) Preparation / Chapter 2. --- Bleomycin Preparation / Chapter 3. --- 2.5% pentobarbitone Preparation / Chapter 4. --- Animal Preparation / Chapter 4.1 --- Control (Normal) group / Chapter 4.2 --- A cute lung damage group / Chapter 4.3 --- Chronic lung damage group / Chapter 5. --- Preparation of the animals for VO2 measurement / Chapter 6. --- Measurement of oxygen consumption / Chapter 6.1 --- VO2wb measurement / Chapter 6.2 --- VO2b measurement / Chapter 7. --- Histopathology / Chapter 8. --- Statistics / Chapter Section Three : --- Results --- p.69 / Chapter 1. --- Healthy (Control) group / Chapter 1.1 --- Pulmonary histology / Chapter 2. --- Acute lung damage group / Chapter 2.1 --- Pulmonary histology / Chapter 3. --- Chronic lung damage group / Chapter 3.1 --- Pulmonary histology / Chapter 4. --- Comparison of the pulmonary oxygen consumption among the three groups / Chapter Section Four : --- Discussion --- p.97 / Chapter Section Five : --- Conclusion --- p.111 / Chapter Section Six : --- Future Studies --- p.114 / Chapter Section Seven : --- Bibliography --- p.118

Introdução e Objetivos: considerando a complexidade da natação, o objetivo geral desta dissertação foi investigar o desempenho em 400 m nado crawl (T400), a partir de parâmetros antropométricos, biomecânicos e fisiológicos. Materiais e Métodos: O estudo foi avaliado e aprovado pelo Comitê de Ética em Pesquisa da UFRGS. Participaram 14 nadadores competitivos (21,2 ± 4,15 anos de idade) de nível regional e nacional, que foram avaliados em relação à: (i) antropometria e somatotipo; (ii) parâmetros biomecânicos (frequência média de ciclos de braçadas - FB, distância média percorrida pelo corpo a cada ciclo de braçadas - DB, velocidade média de nado - VN; variação intracíclica da velocidade do centro de massa nos três eixos - VIVx, VIVy, VIVz, índice de coordenação - IdC, duração das fases propulsivas e não propulsivas - Fprop e Fnprop, e tempo propulsivo - Tprop); e (iii) parâmetros fisiológicos (consumo de oxigênio – VO2, concentração sanguínea de lactato – [LA], e percepção subjetiva de esforço – PSE). Dados foram obtidos antes, durante (M1, M2, M3 e M4) e após o T400. Parâmetros biomecânicos de nado foram obtidos por cinemetria 3D e método e-zone para cálculo da localização do centro de massa. VO2 foi mensurado respiração por respiração utilizando o ergoespirômetro K5 e esnorquel Aquatrainer (ambos Cosmed). Foi utilizada estatística descritiva e inferencial (comparativa e correlacional). Resultados: (i) nadadores de 400 m possuem somatotipo meso-ectomórfico; (ii) não houve mudanças nos parâmetros biomecânicos ao longo do teste (exceto maior FB no M4); (iii) o VO2 do M1 foi o menor em comparação a M2, M3 e M4, sendo que o maior valor de VO2 (pico: 67,6 ± 8,9 ml·kg-1·min-1) foi identificado nos últimos trechos do T400; após o termino do teste a [LA] foi de 9,03 ± 0,04 mmol.l-1 e PSE de 17,6 ± 1,2 pontos. Entre as variáveis fisiológicas, a [LA] correlacionou-se inversamente com o desempenho (r = -0,61). Conclusão: Nadadores incrementam a FB ao fim do teste, buscando, pelo menos, incrementar a VN. Mesmo que a VN tenha se mantido constante, os maiores valores foram encontrados ao final do teste. Ao mesmo tempo, o consumo de oxigênio incrementou no último quarto do teste, possivelmente de acordo com o aumento da FB. / Introduction and Objectives: considering the swimming complexity, the general objective of this study was to investigate the performance in 400 m front crawl (T400) with anthropometric, biochemical and physiological parameters. Materials and Methods: the Ethics Committee of the UFRGS approved the study. Fourteen competitive swimmers (21.2 ± 4.15 years old) of regional and national level were assessed in relation to: (i) anthropometry and somatotype; (ii) biomechanical parameters (mean rate of stroke cycles - SR, mean stroke length - SL, mean swimming speed - SS; center of mass intracyclic velocity variation in the three axes - VIVx, VIVy, VIVz; index of coordination - IdC, duration of the propulsive and non-propulsive phases - Fprop and Fnprop; and propulsive time - Tprop); and (iii) physiological parameters (oxygen consumption - VO2, blood lactate concentration - [LA], and perceived exertion - PE). Data were obtained before, during (M1, M2, M3 and M4) and after T400. Biomechanical parameters of swimming were obtained by kinematics and 3D method e-zone for calculating the center of mass location. VO2 was breath-by-breath measured using the K5 ergospirometer and snorkels Aquatrainer (both Cosmed). It used descriptive and inferential statistics (comparative and correlational). Results: (i) 400 m swimmers are meso-ectomorphic somatotype; (ii) no changes in biomechanical parameters during the test (except increased SR in the M4); (iii) VO2 in the M1 was lower when compared to M2, M3 and M4, and the largest VO2 value (peak: 67.6 ± 8.9 ml·kg-1·min-1) was identified in the last T400 part; after the end of the test the [LA] was 9.03 ± 0.04 mmol·l-1 and PE was17.6 ± 1.2 points. Among the physiological variables, [LA] correlated inversely with performance (r = -0.61). Conclusion: Swimmers increase SR in the end of the test, seeking, at least, to increase the SS. Even the VN has remained constant, the highest values were found at the end of testing. At the same time, the increased VO2 in the last in the T400’s final part possibly is in accordance with the SR increased.

O remo é uma modalidade que depende muito das condições ambientais para ser praticada, tais como vento, chuva e frio, as quais podem atrapalhar e, dependendo da variação, até impedir a sua prática. Por esses motivos, a realização de atividades em ambiente fechado torna-se importante nesse esporte. A alternativa mais utilizada para treinamento e avaliação é o ergômetro de remo Concept2. Contudo, a dinâmica do ergômetro de remo é diferente da dinâmica na água. Na tentativa de contornar parte dos problemas associados ao uso do ergômetro, a empresa fabricante do Concept2 criou um acessório chamado slide. O objetivo do presente estudo foi verificar as respostas fisiológicas (consumo de oxigênio, freqüência cardíaca e concentração de lactato) do remador em três situações diferentes: ergômetro de remo, ergômetro de remo com o acessório slide e na água, bem como comparar a contribuição energética de cada situação. Oito sujeitos foram submetidos a cinco testes no total, sendo três deles a simulação da prova de 2000 metros em cada situação e outros dois testes progressivos até a exaustão no ergômetro de remo com e sem o slide. Os principais resultados do estudo foram: a) o perfil metabólico, bem como a demanda energética da prova de 2000m no remo é a mesma, independentemente se ela é realizada no ergômetro de remo Concept2 com ou sem slide ou na água, no barco single-skiff; b) o menor gasto energético total na água está relacionado exclusivamente ao maior tempo necessário para percorrer os 2000m nessa situação; c) a utilização do acessório slide no ergômetro de remo Concept2 não implica em alterações no perfil fisiológico da atividade; d) a utilização do ergômetro de remo no treinamento de remadores produz o mesmo efeito, no que diz respeito aos ajustes fisiológicos agudos, que o treinamento na água / Rowing is a sport that can be subject to environmental conditions as it is practiced outdoors. Wind, rain and cold climates can disturb or even impede the execution of rowing on the water. For that reason, indoor rowing is considered to be an important means of training. The most used form of indoor training and evaluation of athletes is the rowing ergometer Concept II. Nevertheless, outdoor rowing presents dynamic singularities compared to indoor rowing. In order to minimize differences related to rowing on a machine, the manufacturer of Concept II created a device called the slide. The aim of this study was to verify the physiological responses (oxygen consumption, cardiac frequency, lactate concentration) of rowers in three different situations: rowing on an ergometer without and with the slide and rowing on the water. Also, the energy contribution was evaluated. Eight individuals were submitted to five physical tests each. Three of the tests consisted of the simulation of a race in a distance of 2000m in each of the situations defined above, and 2 of the tests consisted of progressive effort until exhaustion in the rowing ergometer with and without the slide. The results obtained were the following a) metabolic profile, as well as energy demand in the 2000 m test was the same if completed on the rowing ergometer with or without the slide or on the water on a single scull. b) the least energy cost on the water was related to the longer time needed to complete the 2000 m test outdoors. C) the use of the slide on the ergometer did not show any changes on the physiological profile of the activity d) the use of the rowing ergometer for training of rowers has the same effect, in terms of physiological adjustments, as training on the water

The bluefin tuna have a variety of distinctive anatomical and physiological adaptations that enhance performance. However, our understanding of bluefin tuna physiology is limited by the logistical difficulties of studying these large pelagic fish. This thesis examines some aspects of the metabolic physiology of the southern bluefin tuna. It provides insight into the high-performance, high-energy demand physiology of bluefin. It also examines the metabolic physiology of the mulloway, another important aquaculture species for which physiological information is currently limited. 1. Routine metabolic rate (RMR) of southern bluefin tuna (SBT) (Thunnus maccoyii), the largest tuna specimens studied so far (body mass = 19.6 kg (± 1.9 SE)) was measured in a large (250,000 l) flexible polypropylene respirometer “mesocosm respirometer”. Mean mass-specific RMR was 460 mg kg⁻¹ h⁻¹ (± 34.9) at a mean water temperature of 19°C. When total RMR is added to published values of other tuna species at equivalent swimming speeds, there is a strong allometeric relationship with body mass (654 • Mb ⁰·⁹ ⁵, R ² = 0.97). This demonstrates that interspecific RMR of tuna scale with respect to body mass similar to that of other teleosts, but is approximately 5-fold higher than the standard metabolic rate (SMR) of other active teleost species. 2. This study reports on the first measurements of the metabolic cost of food digestion and assimilation (specific dynamic action, SDA) of a tuna species. Oxygen consumption (MO₂) and swimming velocity of southern bluefin tuna (SBT) (Thunnus maccoyii) were elevated for periods between 20-45 h (longest for the largest rations) post-ingestion of sardines (Sardinops sagax). It is suggested that the purpose of increased swimming velocity was to increase ventilation volume as a response to the enhanced metabolic demand associated with SDA. The magnitude of SDA as a proportion of gross energy ingested (SDA coefficient) averaged 35 ± 2.2 %. This demonstrates that the absolute energetic cost of SDA in SBT is approximately double that recorded in other teleost species. 3. This study examines the effects of sardines (Sardinops sagax) with high- (12.9%) or low- (1.8-4.0%) lipid level on specific dynamic action (SDA) and swimming velocity of southern bluefin tuna (SBT) (Thunnus maccoyii). Fish swam faster during the SDA period with the increase in velocity being greatest for the fish that ingested the high-lipid sardine. Magnitude of SDA was also greater for fish that ingested the high-lipid sardines. However, the energetic cost of SDA as a proportion of ingested energy was not significantly different between fish that ingested the high- (34.3 ± 2.4%) and low-lipid sardines (31.5 ± 2.9%). These results confirm that the high energetic cost of SDA is ecologically relevant. 4. In this study the metabolic and behavioural responses of both fasted and postprandial southern bluefin tuna (Thunnus maccoyii, SBT) to low dissolved oxygen (DO) was examined. In moderate hypoxia (4.44 and 3.23 mg l⁻¹), swimming velocity (U) and routine metabolic rate (RMR) of fasted fish was mildly enhanced. At 2.49 mg l⁻¹, U increase to over double in the normoxic speed, possibly as an escape response. At 1.57 mg l⁻¹, both U and RMR were suppressed and SBT failed to survive the entire 20 h exposure period. This reveals that SBT are remarkably well adapted to low DO. Feeding did not greatly influence their hypoxia tolerance. In a subsequent experiment there were no significant differences in U, RMR and gastric evacuation rates of postprandial SBT in hypoxia (2.84 mg l⁻¹) compared to those in normoxia (7.55 mg l-¹). 5. In this study, 768 h of simultaneous recordings of metabolic rate (MR, = heat production) and visceral temperature were made in both fasted and postprandial southern bluefin tuna (SBT, Thunnus maccoyii) of two sizes (~10 and 20 kg) and at two water temperatures (~19 and 16°C). Duration and magnitude of specific dynamic action (SDA) were strongly related to duration and magnitude of postprandial visceral warming providing the first empirical evidence of a link between SDA and postprandial visceral warming. Visceral temperature of fasted SBT was also directly related to MR. In this case, source of heat is thought to be metabolic work performed within the red muscles which warmed the viscera through thermal conductance. Visceral excess temperatures were over 1°C warmer in larger than smaller SBT. Better heat retention ability of the larger SBT is likely attributed to improved retia mirabilia development and greater thermal inertia. SBT at 16°C maintained visceral excess temperatures significantly warmer than similarly sized fish at 19°C. This demonstrates some ability of SBT to physiologically regulate visceral warming. 6. In this study, the effect of progressively severe hypoxia levels on the swimming performance and metabolic scope of juvenile mulloway (Argyrosomus japonicus) were investigated. In normoxic conditions (6.85 mg l⁻¹), standard metabolic rate (SMR) and cost of transport were typical for subcarangiform fish species. Mulloway had a moderate scope for aerobic metabolism (5 times the SMR). The critical dissolved oxygen level was 1.80 mg l⁻¹ revealing that mulloway are well adapted to hypoxia. In all levels of hypoxia (5.23, 3.64, and 1.86 mg l⁻¹) the active metabolic rate was reduced however, the critical swimming velocity was reduced only at 3.64, and 1.86 mg l⁻¹. Mulloway metabolic scope was significantly reduced at all hypoxia levels, suggesting that even mild hypoxia may reduce growth productivity. / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007

Cold seeps are areas of high biomass in the deep-sea, the impacts of these food-rich environments upon the sediment community is unknown in the Gulf of Mexico. The structure and function of benthic communities was investigated at food-rich and food-limited sites on the northern Gulf of Mexico continental slope. Cold seeps were richer in macrofauna densities and total sediment respiration, but were poorer in biomass and taxa diversity than normal slope communities. Decreased diversity is seen at most chemosynthetic communities and suggests a competition for resources. The spatial extent of these results at seeps is unknown and may be a localized, bioenhancement effect caused by seeping fluids.