Shellfish and seaweed mariculture increase atmospheric CO2 absorption by coastal ecosystems

With an annual production of >10 million t (Mt), China is the largest producer of cultivated shellfish and seaweeds in the world. Through mariculture of shellfish and seaweeds, it is estimated that 3.79 ± 0.37 Mt C yr–1 are being taken up, and 1.20 ± 0.11 Mt C yr–1 are being removed from the coastal ecosystem by harvesting (means ± SD). These estimates are based on carbon content data of both shellfish and seaweeds and annual production data from 1999 to 2008. The result illustrates that cultivated shellfish and seaweeds can indirectly and directly take up a significant volume of coastal ocean carbon—shellfish accomplish this by removal of phytoplankton and particulate organic matter through filter feeding, and seaweeds through photosynthesis. Thus, cultivation of seaweeds and shellfish plays an important role in carbon fixation, and therefore contributes to improving the capacity of coastal ecosystems to absorb atmospheric CO2. Because the relationship between mariculture and the carbon cycle of the coastal ecosystem is complicated and the interaction between the 2 processes is significant, such studies should be continued and given high priority.