Phytoplankton morphology affects susceptibility to aggregation via microscale turbulence

Phytoplankton are subject to microscale turbulence which drives aggregation creating phytoplankton blooms. If the aggregated species produce toxins, blooms may become detrimental, resulting in harmful algae blooms. To understand how morphology affects aggregation, disk-shaped Coscinodiscus wailesii (50-100μm pervalar axis, 100-200μm diameter) and rod-shaped Stephanopyxis sp. (20-100μm length, 40-60μm diameter) were exposed to four intensity levels of a Burgers vortex mimicking a dissipation-scale turbulent eddy. With this approach, particle-flow interaction is essentially deconstructed to examine the dynamics around a dissipation-scale eddy. Three-dimensional trajectories are compared to trajectories of a neutrally-buoyant, spherical particle (Orgasol; 50μm diameter) across vortex intensity levels. Preliminary results reveal that C. wailesii has similar motion to Orgasol, while Stephanopyxis sp. decreases net to gross displacement ratio and trajectory-flow alignment with increasing turbulence level to a greater extent than both C. wailesii and Orgasol, suggesting that its longer chain-shape influences how it interacts with a dissipation-scale eddy and, ultimately, microscale turbulence.