Ocean acidification (OA), as a part of global climate change, is considered one of the most pressing threats to marine ecosystems. Research on the impacts of OA is a rather new field, and the full implications of these changes are still unclear. In this project we intend to design and deploy a platform of modular structures at a shallow-water hydrothermal vent recently discovered in the Faial-Pico channel, with gas composition (95% CO2) ideal for long-term studies on the effects of OA on benthic communities. This will grant us the opportunity to develop a broad range of experiments in natural extraordinary conditions. Experimental work will investigate how decreasing pH will affect the diversity and functioning of microbial communities living inside hard carbonate substrates, soft sediments and in association with corals. Microbial communities play key roles in several biological and ecological processes such as carbonate dissolution, organic carbon degradation and invertebrate symbiosis. The effects of decreasing pH will be tested by placing sediment bags, cages with carbonate substrates and Antipathella wollastoni coral fragments along a gradient of pH starting from the venting gas emission, and in a reference site. In addition, translocation experiments of sediments and coral fragments will allow the study of eventual phase-shifting reversals of the microbal communities. Results of this study will provide information on microbial ability in transferring organic carbon to higher trophic levels, determine the pH thresholds that may cause the dissolution of different carbonate forms and predict how the composition of carbonate sediments will change in the future.
Ocean acidification studies in the Azores: using a shallow-water hydrothermal vent as a natural laboratory
1) Determine pH-induced changes in the diversity and functioning of microbial communities inhabiting sediments
2) Determine the effects of decreasing pH on chemical and biogenic dissolution rates of biological substrates common in the Azores region (shells, echinoderm and coral skeletons)
3) Evaluate the effect of decreasing pH on the ecologically-important coral species Antipathella wollastoni and its symbiotic assemblages