Effects of coastal shellfish farming on dimethylsulfide production

Dimethylsulfide (DMS) plays an important role in the sulfur biogeochemical cycle and cloud formation on Earth. In the past few decades, coastal shellfish breeding facilities have developed rapidly in shallow coastal regions. However, the effects of coastal shellfish farming on DMS production remain controversial at present. The Yantai offshore is an important shellfish farming region in northern China and the effect of shellfish farming on DMS production was explored combining field investigation and laboratory cultivation in this study. The results showed that coastal shellfish farming can promote the conversion of DMSP to DMS, especially in the shellfish rapid growth period and harvest period. However, different from the zooplankton "sloppy feeding", the shellfish "filter-feeding" first repackages the phytoplanktonic DMSP into fecal DMSP, and then degrades DMSPp into DMS by attracting attached bacteria. Throughout the entire shellfish farming period, average DMS flux in shellfish region was 1.37 mu mol m(-2) d(-1) higher than that in non-shellfish region. Based on the investigation results Yantai coastal shellfish farming region, it can be estimated that the increment of DMS caused by Chinese coastal shellfish farming can reach 2.96 x 10(6) mol per year.