An analytical model of induced flow velocity by vertically migrating swarms informed by 3D organism tracking

The fluid transport associated with swarming vertical migrations of zooplankton in the ocean may have significant implications for climate modeling, solute mixing, and gas exchange. We utilize brine shrimp (Artemia salina) as a model organism to investigate the effects of collective movement on the fluid environment. Leveraging the positive phototaxis of brine shrimp, we induce synchronized vertical migration and capture three-dimensional trajectories of individual swimmers within the swarm with a single camera and scanning laser. An analytical model estimates the mean convection velocity induced by the animals’ combined wakes. Individual animal wake structures are derived semi-empirically and combined with captured animal trajectories to construct a theoretical fluid velocity field based on a momentum-conserving model of wake superposition.