| Summary: | Memoria de tesis doctoral presentada por Juancho Movilla Marínpara obtener el título de Doctora en Oceanografía por la Universidad de las Palmas de Gran Canaria (ULPGC), realizada bajo la dirección del Dr. Carles Pelejero Bou y de la Dra. Eva María Calvo Costa del Institut de Ciències del Mar (ICM-CSIC).-- 236 pages [EN] Since the beginning of the industrial era, oceans have absorbed almost one-third of the carbon dioxide (CO2) released to the atmosphere by anthropogenic activities, mitigating its greenhouse effect and its influence on Earth’s climate. However, a consequence of this absorption is ocean acidification (OA), a process that has emerged as potentially disturbing for marine ecosystems and has become a research priority in recent years. The Mediterranean is already one of the most impacted seas in the world, facing many anthropogenic pressures. However, it is still under debate if the impact of OA will be stronger in this semi-enclosed sea than in the global ocean. In this thesis, we contribute to the still limited knowledge on the mid- to long-term effects of OA on nine key benthic species from the two most important Mediterranean calcareous ecosystems in terms of species diversity, the shallow coralligenous and the deep-sea communities. For that purpose, we started by developing a system for experimental pH manipulation in aquaria that allowed us to expose the organisms to different pH and temperature conditions, simulating the present values and those expected by the year 2100. We assessed the response in the calcification rate, the status of the carbonated supporting framework (microstructure, specific microdensity and porosity) and the metabolic balance (organic matter, carbohydrates, lipids and proteins content in the tissue) in each single species. In terms of calcification, the most affected species was the octocoral Corallium rubrum, which exhibited a mean decrease of about 59%, followed by zooxanthellate corals Cladocora caespitosa and Oculina patagonica, with a decrease of 35 and 32%, ...
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