Abstract
Aerosol depositions provide nutrients, trace metals, and organic compounds for marine environments that enhance ocean productivity and carbon sequestration, and indirectly influence atmospheric carbon dioxide concentrations and climate change. However, most of the microbial dynamics in seawater deposited via aerosols are analyzed using chemical analysis by means of field surveys and model analyses. We performed a shipboard experiment using seawater spiked with snow-solution including aerosols in order to elucidate the influence of aerosol additions on the growth and community structures of marine microorganisms. The snow samples including aerosol particles transported by westerly winds were obtained from Mt. Tateyama. The seawater spiked with snow-solution was incubated on a ship at the sampling site in the Pacific Ocean at a distance of 70 km from Omaezaki in Shizuoka prefecture. The sampling site is under oligotrophic conditions. The chlorophyll concentrations of micro-plankton （＞20 μm） indicated an increase in the snow-solution spiked seawater corresponding to the decrease in nitrate during the 3 days of incubation. In total bacterial communities, the number of Rhodobacterace and OM60 clade increased in the snow-solution spiked seawater. Presumably, the deposition of aerosols included in snow can potentially alter microalgal amounts and bacterial communities structures in marine environments.
