Loading...
Publication
Effects of exposure to elevated temperature and different food levels on escape response and metabolism of early stages of white seabream, Diplodus sargus
Authors
Advisor(s)
Abstract(s)
O final da fase larvar é um período crítico na vida dos peixes, sujeito a elevadas taxas de mortalidade, principalmente devido à predação. O sucesso nesta fase é, então, modelado pela capacidade de escapar a predadores. A literatura sugere que o aumento da temperatura pode afetar a resposta de fuga e metabolismo, contudo poucos estudos têm focado na resposta aguda e potencial de aclimatação, através da plasticidade de desenvolvimento. Aqui, pretendemos avaliar os efeitos da exposição aguda e de longo prazo a temperaturas elevadas na resposta de fuga e taxas metabólicas padrão (SMR), nas fases iniciais de Diplodus sargus. Adicionalmente, como a disponibilidade alimentar pode modelar a resposta ao aquecimento, testámos os efeitos da exposição a temperatura elevada e indisponibilidade de alimento, como fatores individuais e em interação, na resposta de fuga e SMR. Os tratamentos de temperatura foram ajustados à temperatura ambiente (19°C) e elevada (22°C). Os tratamentos de alimentação foram estabelecidos como ad libitum e alimentação reduzida (50% do ad libitum). A resposta de fuga e SMR foram medidos após a temperatura elevada ser atingida (exposição aguda) e após 4 semanas (exposição a longo prazo). O aquecimento agudo teve um efeito significativo na resposta de fuga e aumentou ligeiramente a SMR. Contudo, a longo prazo, parece existir uma aclimatação da resposta de fuga e SMR. A indisponibilidade de alimento, ao interagir com a temperatura elevada, levou a um aumento da latência e redução da SMR, sugerindo que os peixes regulam as taxas metabólicas em função da disponibilidade alimentar.
The end of the pelagic larval stage is a critical period in the life of fish, subject to high mortality rates, mostly due to predation. Success at this stage is then modulated by the ability to escape from predators. The literature suggests that an increase in temperature can affect escape response and fish metabolism, however few studies have focused on the acute sensitivity responses and the potential for acclimation through developmental plasticity. Here, we aimed at evaluating the acute and long-term effects of exposure to warming conditions on the escape response and Standard Metabolic Rates (SMR) of early life stages of the white seabream, Diplodus sargus. Additionally, as food availability may modulate the response to warming, we further tested the effects of long-term exposure to high temperature and food shortage, as individual and interacting drivers, on escape response and SMR. Temperature treatments were adjusted to ambient temperature (19°C), and a high temperature (22°C). Feeding treatments were established as ad libitum and short fed (50% of ad libitum). Escape response and SMR were measured after the high temperature was reached (acute exposure), and after 4-weeks (long-term exposure). Acute warming had a significant effect on escape response, and slightly increased SMR. In the long-term, however, there seems to be an acclimation of the escape response and SMR. Food shortage, interacting with high temperature, led to an increase in latency response and a significant reduction in SMR, which suggests that fish might regulate metabolic rates as a function of food availability.
The end of the pelagic larval stage is a critical period in the life of fish, subject to high mortality rates, mostly due to predation. Success at this stage is then modulated by the ability to escape from predators. The literature suggests that an increase in temperature can affect escape response and fish metabolism, however few studies have focused on the acute sensitivity responses and the potential for acclimation through developmental plasticity. Here, we aimed at evaluating the acute and long-term effects of exposure to warming conditions on the escape response and Standard Metabolic Rates (SMR) of early life stages of the white seabream, Diplodus sargus. Additionally, as food availability may modulate the response to warming, we further tested the effects of long-term exposure to high temperature and food shortage, as individual and interacting drivers, on escape response and SMR. Temperature treatments were adjusted to ambient temperature (19°C), and a high temperature (22°C). Feeding treatments were established as ad libitum and short fed (50% of ad libitum). Escape response and SMR were measured after the high temperature was reached (acute exposure), and after 4-weeks (long-term exposure). Acute warming had a significant effect on escape response, and slightly increased SMR. In the long-term, however, there seems to be an acclimation of the escape response and SMR. Food shortage, interacting with high temperature, led to an increase in latency response and a significant reduction in SMR, which suggests that fish might regulate metabolic rates as a function of food availability.
Description
Dissertação de Mestrado apresentada no ISPA – Instituto Universitário para obtenção de grau de Mestre na especialidade de Biologia Marinha e Conservação
Keywords
Aclimatação de desenvolvimento Alterações climáticas Comportamento Diplodus sargus Fisiologia Behaviour Climate change Developmental acclimation Diplodus sargus Physiology