Life of Cyanobacteria in Turbulent Lakes

Forming and maintaining large colonial structures is essential for the success of bloom-forming cyanobacteria. Yet, the influence of the lake hydrodynamics in the modulation of the colony size is not well understood. We investigate how fluid flow results in aggregation and fragmentation of cyanobacterial colonies. Laboratory cell cultures are subjected to shear at the inertial regime, and the time evolution of the colony size distribution is measured with direct imaging of the suspension. A numerical model based on non-linear population dynamics describes the measured size distribution. Finally, we categorize the flow conditions in which cell fragmentation and aggregation are relevant at various geophysical flow conditions.