SCOPE FALKOR Eukaryotic Metatranscriptomes Raw sequence reads
Marine protists and their metabolic activities are intricately tied to the cycling of nutrients and 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 throughout the water column have not been explored extensively. To investigate how mesoscale eddies affect protistan communities, a metatranscriptomic study was conducted at adjacent cyclonic and anticyclonic eddy sites in the oligotrophic ocean at 4 depths from 25 m to 250 m. The impact of depth on protistan community composition and metabolism was greater than that of eddy polarity. The effects of eddy polarity on protistan communities were the most pronounced at depths below the mixed layer and extended into the upper mesopelagic zone. An analysis of transcripts associated with the nutritional physiology of protists at 150 m depth revealed that cyclonic eddies may support a more heterotrophic protistan community, while anticyclonic eddies may support a more phototrophic protistan community. The results obtained from this study suggest that eddies alter the metabolism and nutritional physiology of protists in the lower euphotic zone and may therefore impact carbon export from the euphotic zone.