Clam farming generates CO2: A study case in the Marinetta lagoon (Italy)

Respiration and calcium carbonate (CaCO3) production by the farmed short-neck clam Ruditapes philippinarum were calculated to assess their importance as carbon dioxide (CO2) sink/source in a lagoon of the Po Delta River (Italy). Biomass and calcimass were established by monthly harvests during a 1-year period (2009). The ratio of CO2 released to CaCO3 precipitated was calculated as a function of the near-bottom temperature. From our estimates, R. philippinarum sequestered 8.18 mol CO 2 m - 2 year - 1 for shell formation, but the CO2 fluxes due to respiration and calcification resulted 22.7 and 5.56 mol CO 2 m - 2 year - 1 , respectively. Clam farming seems therefore to be a significant additional source of CO2 to seawater.