From single species to the community level: Exploring under-researched avenues in protist ecology and protist-prokaryote interactions

Two case studies of under-researched fields in protist-prokaryote interactions are analysed: 1. Bacteria adapted to carbon-starvation are shown to present species-specific patterns in their vulnerability to a protist grazer, including strong resistance. 2. Protist communities in Baltic Sea pelagic redoxclines are shown to present a characteristic structuring. Protist bacterivory is the main prokaryotic mortality factor until hydrogen sulphide begins to rise and can control the growth of a chemolithoautotrophic bacterial key-player, proving the ecological relevance of protists in these zones