Protistan community composition and metabolism in the North Pacific Subtropical Gyre: Influences of mesoscale eddies and depth

Marine protists and their metabolic activities are intricately tied to the cycling of nutrients and the flow of energy through microbial food webs. Physiochemical changes in the environment, such as those that result from mesoscale eddies, may impact protistan communities, but the effects that such changes have on protists are poorly known. A metatranscriptomic study was conducted to investigate how eddies affected protists at adjacent cyclonic and anticyclonic eddy sites in the oligotrophic ocean at four depths from 25 to 250 m. Eddy polarity impacted protists at all depths sampled, although the effects of eddy polarity were secondary to the impact of depth across the depth range. Eddy-induced vertical shifts in the water column yielded differences in the cyclonic and anticyclonic eddy protistan communities, and these differences were the most pronounced at and just below the deep chlorophyll maximum. An analysis of transcripts associated with protistan nutritional physiology at 150 m revealed that cyclonic eddies may support a more heterotrophic community, while anticyclonic eddies promote a more phototrophic community. The results of this study indicate that eddies alter the metabolism of protists particularly in the lower euphotic zone and may therefore impact carbon export from the euphotic zone. A metatranscriptomic study of adjacent cyclonic and anticyclonic eddies in the oligotrophic ocean revealed that eddy polarity had a marked impact on protistan community composition, metabolism, and nutritional physiology at the base of the euphotic zone. These findings have important implications for the cycling of organic carbon in the ocean.image

Automated summary

Marine protists and their metabolic activities are influenced by physiochemical changes in the environment, such as mesoscale eddies. A metatranscriptomic study investigated the impact of eddies on protists at different depths in the oligotrophic ocean. The study found that eddy polarity affected protist communities, metabolism, and nutritional physiology, particularly at the lower euphotic zone.