Atmospheric Deposition Promotes Relative Abundances of High‐Dimethylsulfoniopropionate Producers in the Western North Pacific.

Haptophytes and Dinoflagellates are two cosmopolitan algae associated with dimethylsulfoniopropionate (DMSP) synthesis, which regulates the marine biogenic flux of DMS to the atmosphere with potential effects on global climate. Attempting to reveal the potential impact of atmospheric deposition on the growth of high‐DMSP producers, four bioassay experiments were conducted in the western North Pacific (WNP) by adding aerosols, nutrients, and trace metals. Our results showed that the percentage of high‐DMSP producers increased substantially from coastal seas (<1%) to the open ocean (∼17%) with the dominance of Dinophyceae and Haptophyceae, respectively. Aerosol additions largely increased the percentage of high‐DMSP producing species in the subtropical gyre of WNP. Specifically, atmospheric dissolved inorganic nitrogen, soluble Cu and Fe promoted Dinophyceae taxa, Chrysochromulina, and Phaeocystis and E. huxleyi, respectively. It is very likely that atmospheric deposition could lift the relative abundance of high‐DMSP producers in the vast oligotrophic oceans and potentially contribute to the climate change. Plain Language Summary: Dimethylsulfoniopropionate (DMSP) is an important precursor of dimethyl sulfide (DMS) and metabolite of algae, which may alter the radiative balance and regulate the global climate. We have conducted four bioassay experiments in different regions of the WNP, simulating atmospheric inputs of nutrients and trace metals analogue to their contents in aerosols. The proportion of high‐DMSP producers increased substantially with the distance offshore, and the dominant species transferred from Dinophyceae to Haptophyceae. It was demonstrated that atmospheric deposition could elevate the proportion of high‐DMSP producers in the oligotrophic ocean rather than in coastal seas. Their larger size compared with Cyanobacteria and special mechanism of metal digestion might be the reason. With the intensive human activities and increasing atmospheric deposition, this stimulation effect may be significantly enhanced and the subsequent climate effects are non‐negligible, especially in those oligotrophic regions. Our results may provide new insights into the ecological effects and climate change. Key Points: Dinophyceae and Haptophyceae were the prime high‐dimethylsulfoniopropionate (DMSP) producers in the coastal and oligotrophic oceans, respectivelyAtmospheric deposition could elevate the proportion of high‐DMSP producers in the oligotrophic oceanDissolved inorganic nitrogen and Cu increased the proportion of Chrysochromulina whilst Fe benefited Phaeocystis and E. huxleyi [ABSTRACT FROM AUTHOR]