Global and local impacts on Atlantic RHODOlith beds: Implications for estimates of blue CARbon ecosystem services

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Rhodolith beds are one of the most extensive benthic ecosystems along the Atlantic coasts and key environments to continental shelf resilience. Besides providing substrate and habitat for numerous other algae and sessile invertebrates, their ability to calcify, their high abundance and biomass, makes rhodoliths major carbonate producers. Recent empirical estimations suggest that the carbonate marine deposits generated by these organisms represent a total potential carbon sink of 0.4 x 109 t C yr-1. Hence, giving the increasing role of marine ecosystems in the storage of blue carbon, rhodolith beds may represent a not yet considered significant carbon store. Regarding carbon sequestration, studies on rhodolith bed community metabolism are scarce and so far only available for two temperate beds that indicate that they can act both as CO2 source and organic carbon sink. As many marine ecosystems, rhodolith beds are currently under threat related to global climate change (GCC), with local impacts due to increasing coastal urbanization, potentially lowering even further their resilience. Thus, by using a physiological approach, this project will provide much needed information on the basic mechanistic understanding of rhodolith metabolism (photosynthesis, calcification), rhodolith responses to global and local stressors, and rhodolith bed community metabolism and carbon storage along a latitudinal gradient. Taken together, this information will allow assessing the importance of rhodolith beds as natural carbon sinks, thus, help ascertain whether these ecosystems meet the requirements to be integrated into climate mitigation policy, and will further allow quantifying the effects of GCC on their carbon sequestration and storage ability. In addition, it will help recognizing potential interactions between global and local stressors, hence, aid in the development of effective local conservation and management strategies.