Grazing at Axial

Microorganisms are the ancestral forms of life on our planet and have been instrumental in shaping all of Earth?s environments into what they are today. In the ocean, microbial prokaryotes and eukaryotes form the foundation of marine food webs through their activity and interactions. Single-celled microbial eukaryotes (or protists) are some of the most important species on the planet, yet our understanding of how their activities influence and regulate the ocean ecosystem is poorly constrained. At deep-sea hydrothermal vents in particular, our understanding of microbial food web dynamics is incomplete without including the role of microbial eukaryotes. This project provides quantification of phagotrophic protistan grazing on the microbial communities inhabiting the highly productive diffuse vent mixing zone at hydrothermal vents, where the vent fluid-seawater interface promotes an increase in biological activity compared to the surrounding deep seawater. The results are contributing novel insights into the diversity and metabolic activities of the microbial eukaryotic community at vent fluid-seawater interfaces, establish the extent to which microbial eukaryotes impact primary production in the deep ocean by quantifying predation pressure, and estimate the amount of carbon transferred from primary producers to larger organisms.