| Summary: | Dissertação de mestrado em Ecologia The wide recognition of a global increase temperature and acidification in the oceans and their impact on marine ecosystems has led to a burgeoning of research on the subject not always free of controversies. In this experimental study we explored the short term combined effects of increasing temperature and CO2 on the functional performance of some coastal marine species. Thus, we carry out an orthogonal experiment where we manipulated simultaneously pH (two levels: normal, pH 8.1 and low pH 7.7) and temperature (three temperatures: low: 16 ºC, medium 19 ºC and high 22 ºC). We examined the performance growth and survival of two seaweed species: Fucus serratus and Chondrus crispus, and three invertebrate species: Dynamene sp., Gammarus locusta and Gibbula umbilicalis. We set up analytical procedures on those species to examine the effects of acidification and warming on the level of oxidative stress using the biomarkers LPO and GST. Finally we also performed feeding experiences to examine the effects of climate drivers on the interaction seaweed-grazers. Our results showed differential effects of climate change-related stressors on the organisms examined. Temperature seemed to control seaweeds growth and no significant effects were found for pH. In the case of the animals pH was more important and interacted with temperature strongly in the survival rate of these grazers. These different vulnerability appeared to shape also indirect effects like grazing rates. Short term experiments have limited value to forecast the future impacts of climate change, however they help to understand the direction and intensity of the potential impacts and also to identify likely interactions among drivers. O crescente reconhecimento do aumento de temperatura e acidificação do oceano e o seu impacto na biodiversidade tem levado a um crescente número de pesquisas sobre o tema que nem sempre está livre de controvérsias. Neste trabalho experimental exploramos os efeitos combinados a curto prazo ...
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