The transcriptomic response of the cold-water coral Desmophyllum dianthus to experimental changes in pH

• Main Author: Niedzwiedz, Sarina
• Format: Thesis
• Language: unknown
• Published: 2021
• Subjects: Ocean acidification
• Online Access: https://epic.awi.de/id/eprint/55262/; https://epic.awi.de/id/eprint/55262/1/MasterThesis_SarinaNiedzwiedz.pdf; https://hdl.handle.net/10013/epic.a58f8ad2-a8f5-42f3-b654-fb344c9ede9b

The seawater pH is influenced by the interaction of various natural physical and biological factors. Since the beginning of industrialisation, anthropogenic activities are also having a significant impact on the seawater pH, as the atmospheric increase of the carbon dioxide (CO2) concentration led to an enrichment of the ocean with CO2. The release of protons during the reaction of CO2 with water molecules results in a declining pH (ocean acidification; OA). Apart from the seawater pH, the aragonite saturation state (Ωarag) is commonly used to measure the OA, as it describes the ‘easiness to calcify’ and is therefore biologically relevant. With decreasing pH, the Ωarag is also decreasing and calcifying organisms have to invest more energy to maintain their calcium carbonate structures, most prominently in cold and deep waters. Therefore, scleractinian cold-water corals (CWCs), such as the cosmopolitan species Desmophyllum dianthus, were thought to be among the taxa most threatened by OA, as they are mainly restricted to water temperatures between 4–12 °C and water depths below 50 m. However, their reported occurrence in aragonite under-saturated waters indicates that they are able to mitigate the negative impacts of the low Ωarag. The aim of this study was to gain information on the regulations and mechanisms that allow the CWC D. dianthus to thrive under low-pH conditions. An understanding of the physiological and molecular processes affected by low-pH conditions will help to assess the development and future biogeographic distribution of D. dianthus. Therefore, corals acclimated to pH 8.0 were exposed for two weeks to low-pH conditions (pH 7.4), to assess their short-term acclimation potential to an experimental reduction of the pH conditions. Afterwards, the pH was turned to pH 8.0 for two months, to determine their recovery potential. Corals being exposed to pH 8.0 during the whole experiment served as control. Physiological and transcriptomic response parameters were measured at various sampling times ...