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Effect of temperature on broadnosed pipefish, Syngnathus typhle, behaviour, body condition and survival
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Abstract(s)
A temperatura é um fator determinante para os organismos ectotérmicos, como os
peixes. Compreender de que forma o aquecimento do oceano tem impacto nas espécies, a nível
individual e populacional, é importante para a sua gestão e conservação. O presente estudo
testou os efeitos da exposição prolongada a temperatura elevada no comportamento, condição
física e sobrevivência da marinha-de-focinho-grosso, Syngnathus typhle. Os indivíduos foram
expostos a duas temperaturas (20ºC e 24ºC) durante 4 meses. Foram feitas observações
comportamentais três vezes por semana e os indivíduos pesados e medidos quinzenalmente. Os
resultados do estudo sugerem que os comportamentos de natação e repouso não foram afetados
pela temperatura, mas variaram ao longo do período de exposição; já o comportamento de
movimentação lenta foi afetado pela temperatura, tendo os peixes mantidos a 24ºC passado
mais tempo neste tipo de movimento. Foram observadas diferenças na condição física,
associadas à exposição prolongada à temperatura elevada, observando-se indivíduos mais
pequenos e com menor peso. A sobrevivência foi afetada tanto pela temperatura, havendo mais
mortes na temperatura elevada, como pelo tempo de exposição, tendo o número de mortes
aumentado em ambos os tratamentos. Estes resultados sugerem que apesar de não existirem
efeitos a nível de comportamento, a exposição crónica a temperaturas elevadas, previstas para
o final do século, poderá provocar stress térmico nesta espécie de singnatídeo, comprometendo
a sua condição e sobrevivência.
ABSTRACT: Temperature is a determinant factor for ectothermic organisms, like fish. Understanding how ocean warming impacts species at individual and populational level is important to successfully manage and preserve species. This study tested the effects of long-term exposure to temperature on the behaviour, body condition and survival of the broadnosed-pipefish, Syngnathus typhle. Individuals were exposed to two temperatures (20ºC and 24ºC) for 4 months. Behavioural observations took place three times per week, and weight and length were measured every two weeks. Our results show that the swimming and stationary behaviours were not affected by temperature but varied during the exposure period. The slow body movement behaviour was affected by temperature: fish kept under 24ºC spent more time doing this behaviour. Body condition was impacted by long-term exposure to high temperature, resulting in smaller and lighter individuals. Similarly, survival was affected by temperature: high temperature led to more deaths, and increasing numbers of deaths were registered in both treatments due to exposure time. These results suggest that even though behavioural changes are not observed, chronic exposure to high temperatures, such as those predicted by the end of this century, may compromise the condition and survival of this species.
ABSTRACT: Temperature is a determinant factor for ectothermic organisms, like fish. Understanding how ocean warming impacts species at individual and populational level is important to successfully manage and preserve species. This study tested the effects of long-term exposure to temperature on the behaviour, body condition and survival of the broadnosed-pipefish, Syngnathus typhle. Individuals were exposed to two temperatures (20ºC and 24ºC) for 4 months. Behavioural observations took place three times per week, and weight and length were measured every two weeks. Our results show that the swimming and stationary behaviours were not affected by temperature but varied during the exposure period. The slow body movement behaviour was affected by temperature: fish kept under 24ºC spent more time doing this behaviour. Body condition was impacted by long-term exposure to high temperature, resulting in smaller and lighter individuals. Similarly, survival was affected by temperature: high temperature led to more deaths, and increasing numbers of deaths were registered in both treatments due to exposure time. These results suggest that even though behavioural changes are not observed, chronic exposure to high temperatures, such as those predicted by the end of this century, may compromise the condition and survival of this species.
Description
Dissertação de Mestrado realizada sob a orientação da
Doutora Ana Margarida Faria, apresentada no Ispa –
Instituto Universitário para obtenção de grau de Mestre na
especialidade de Biologia Marinha e Conservação.
Keywords
Comportamento Fisiologia Alterações climáticas Syngnathidae Behaviour Physiology Climate change Syngnathidae