| Summary: | Ocean acidification due to increased CO2 emissions derived from anthropogenic activities is affecting marine ecosystems at an unprecedented rate (IPCC 2013). Ocean acidification has the potential to affect the physiological processes due to increasing CO2 levels and lower pH (Riebesell & Tortell 2011). Ocean acidification also impacts trace metal solubility and speciation. Among all trace metals, Fe is the most essential for biological functions of phytoplankton. Coccolithophores is one of the taxa most affected by increased CO2 and the most important coccolithophore is Emiliania huxleyi. This species is responsible for a large fraction of the ocean calcium carbonate production and export to the deep ocean contributing to the regulation of the exchange of CO2 across the ocean-atmosphere interface (Rost & Riebesell 2004). Emiliania huxleyi has been widely studied in many different works, with one or more global change stressors either in laboratory or in natural conditions. However, there is a lack of knowledge on the response to interactive effects of ocean acidification and dissolved Fe at different levels in this species. The aim of this thesis is to gain deeper insight in the physiological response of E. huxleyi to increased CO2 and Fe availability within the food web using mesocosms and also under controlled laboratory experiments. For this purpose, two types of experiments were performed: a mesocosm experiment and a laboratory experiment. The mesocosm experiment and manipulated to achieve combinations of ambient and increased pCO2 and dFe to investigate the physiology response of the coccolithophorid Emiliania huxleyi within a natural plankton community. The experimental work was performed to elucidate the interactive effect of the exposure to UV radiation (UVR) with increased CO2 and/or different Fe levels. Mesocosm experiments showed a higher degree of realism compared to controlled laboratory experiments due to the semi-control conditions. The most important result was that Fe played the major ...
|
|---|