My PhD project is part of the research project ClimScape - Climate change mitigation capacity of the Baltic coastal seascape: identification of hotspot environments for coastal blue carbon sequestration and guidance for sustainable management of Baltic coastal landscapes under global change.

In the Baltic Sea, there is scarce information about the efficiency of Blue Carbon (BC) habitats as natural carbon sinks. There is, however, a wide diversity of coastal vegetation that could be important contributors to carbon sequestration, e.g. eelgrass (seagrass) and many other rooted macrophytes, tidal marshes and macroalgal beds. Rooted vegetated BC habitats store most of its carbon in the underlying sediment where slow microbial decomposition due to low oxygen concentrations makes long-term storage of organic carbon possible. A high organic loading in the sediment combined with low availability of oxygen is in fact a prerequisite for such microbial degradation where potent greenhouse gases (GHGs), such as methane (CH4) and nitrous oxide (N2O), are produced.

Temperature, oxygen, salinity and carbon sources are all factors that influence the microbial community and their functions, which may in turn impact the carbon sequestration capacity and GHG fluxes (and possible emissions to the atmosphere) in coastal BC habitats. These factors are expected to affect the carbon sink capacity of BC habitats in the Baltic Sea, by altering their biogeochemical processes through functional changes of the microbial communities. Little is yet known regarding how this highly variable environment influences the functioning of microbial communities in coastal BC sediments at different spatial and temporal scales and how this in turn affect the BC sink function and capacity.

The overall aim of my PhD is to examine linkages between carbon sources, microbial community patterns and biogeochemical processes to understand drivers of blue carbon sequestration capacity and greenhouse gas (GHG) fluxes in coastal vegetated habitats of the Baltic Sea.