Distributions of DMS and DMSP and the influences of planktonic community assemblages in the Bohai Sea and Yellow Sea

Dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) are important sulfur compounds influenced by community assemblages of plankton. The distributions of DMS, DMSP, DMSP lyase activity (DLA), DMSP-consuming bacteria (DCB), and community structures of phytoplankton and zooplankton were investigated during summer in the Bohai Sea and Yellow Sea. The variety ranges of DMS, dissolved DMSP (DMSP_d), and particulate DMSP (DMSP_p) concentrations in the surface seawater were 1.46-28.52, 5.26-30.21, and 0.91-112.43 nmol/L, with averages of 6.64, 14.27, and 37.53 nmol/L, respectively. The maximum DMS and DMSP_p concentrations appeared at stations H26 and H25 situated northeast of the Yangtze estuary, respectively. These maximum values maybe due to the enriched nutrients brought by the Yangtze River Diluted Water. Significantly positive correlations were observed between the DMS/DMSP_p concentrations/DLA and chlorophyll a (Chl a) concentration. Additionally, the phytoplankton abundances were markedly positively correlated with DMS concentrations and DLA. DCB abundances showed a significant positive correlation with DMSP_d concentrations. These findings indicated that phytoplankton and bacterial communities significantly influenced the DMS and DMSP_d distributions. Furthermore, microzooplankton grazing was demonstrated promote the total DMSP (DMSP_t) turnover. These results elucidate the planktonic community assemblage roles in regulating the distributions of DMSP and DMS, contributing valuable insights into the biogeochemical cycle of organic sulfur compounds.