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Presentation Title: Macroalgae, Blue Carbon and Nature-based Solutions Dorte Krause-Jensen is a professor in marine ecology and biodiversity at the Department of Bioscience and Arctic Research Center, Aarhus University, Denmark. Her research focuses on the ecology, role and nature-based solutions provided by marine vegetated ecosystems, particularly seagrass meadows and kelp forests. Key themes are 1) responses of marine vegetation to global and local pressures, 2) Arctic vegetation and climate change, 3) functional roles and ecosystem services of vegetated coastal ecosystems, emphasizing their capacity as carbon sinks (i.e. blue carbon) and nutrient sinks, 4) protection and restoration of marine vegetation as nature-based solutions to societal and environmental challenges 5) marine vegetation as indicator of ecosystem status and change. Her research portfolio includes basic, strategic and applied research and has wider societal impact due to her role as advisor to Environmental Authorities on environmental monitoring and management. |
Presentation title: Macroalgae, blue carbon and nature-based solutions
Macroalgal habitats are recognized as being the most extensive and productive of all coastal vegetated ecosystems and there is growing attention on their contribution to carbon sequestration in addition to their importance for biodiversity. Yet their global extent and production, which is fundamental for quantifying their importance, have remained poorly assessed and there is still limited data on their contribution to carbon sequestration. I will present results from group efforts over the past few years to address these knowledge gaps.
We have conducted a first data-driven assessment of the global extent and production of macroalgal habitats based on modelled and observed distributions and net primary production (NPP) across habitat types. We find that macroalgae extend across a global area of 6.06-7.22 million km2 and represent a production of 1.32 Pg C annually. This matches the extent and production of the Amazon rainforest. The potential for macroalgal production to be sequestered as blue carbon depends on the lability of the organic matter as well as the transport to a carbon sink beyond the habitat in either fjord- or shelf sediments or in the deep sea. And fingerprinting methods are needed to document the macroalgal origin of the carbon. I will give examples of such efforts to quantify and document macroalgal C-sequestration and discuss potentials and limitations. Due to the positive effect of macroalgae on biodiversity and carbon sequestration, management actions to protect and restore these habitats and sinks may contribute as nature-based solutions to counter the combined biodiversity and climate crisis.