Non-viral predators of marine picocyanobacteria

The Earth's most abundant photosynthetic cells, the picocyanobacteria - Prochlorococcus and Synechococcus - play a fundamental global role in aquatic ecosystems. The success of these picocyanobacteria is interpreted through a cross-scale systems framework that integrates bottom-up controls on growth (e.g., nutrients and light), diversity, and the selective pressures and response to predation. While viral predators are well studied and experimentally tractable, the diverse non-viral predators of picocyanobacteria are disconnected from this framework and experimentally challenging, leaving a major gap in understanding the picocyanobacteria. This review presents existing research on non-viral picocyanobacterial predators and promising research frontiers that will expand knowledge of the ecology and evolution of these crucial microorganisms.