As part of the Blue Carbon project of the Calouste Gulbenkian Foundation, all available information on the temporal and spatial distribution and conservation status of the main blue carbon ecosystems (BCE) in Portugal was collected, to highlight gaps to be addressed for a reliable national assessment, to provide a base line for the design and implementation of CO₂ offset projects and to contribute to the putative inclusion of BCE in the national inventory of greenhouse gas emissions. A database with all variables to estimate carbon stocks and sequestration rates was created. The main conclusions are 1) the BCE area is 85% saltmarsh and 15% seagrass, 2) data to estimate carbon stocks are scarce and outdated; the national estimate of 1 026 Gg, (89% in saltmarsh, 11% in seagrass) has low precision, 3) 88 % of the saltmarsh carbon stock is in Ria Formosa and Ria of Aveiro lagoons and in Tagus Estuary, whereas 72% of the seagrass stock is in Ria Formosa, 4) Ria Formosa is the only system where sequestration rates were measured, so the national estimate of 3 745 Mg year^-1 (78% saltmarsh, 22% seagrasses) is highly unreliable, 5) most BCE are under some protection figure and the ecological state of the water bodies are mostly Reasonable (49%) and Good (32%), 6) the historical loss of BCE area was estimated at 33% for saltmarshes and 9 % for seagrasses, but this is certainly underestimated as there is anecdotal historical evidence of large seagrass areas that have not been quantified. Further BCE research is necessary for sound blue carbon policy and management in Portugal

Primary Presenter: Rui Santos, Centro de Ciências do Mar, CCMAR (rosantos@ualg.pt)

Authors:

Rui Santos, Center of Marine Sciences, CCMAR  (rosantos@ualg.pt)

Paula Ito, Center of Marine Sciences, CCMAR  (paito@ualg.pt)

Carmen de los Santos, Center of Marine Sciences, CCMAR  (cbsantos@ualg.pt)