Bacterial tracking of motile algae assisted by algal cell's vorticity field

TL;DR

This paper proposes that marine bacteria track motile algae through hydrodynamic effects, specifically the vorticity and strain-rate fields generated by algae, which influence bacterial movement.

Contribution

The study introduces a simplified hydrodynamic model showing how bacterial tracking of algae can result from flow fields rather than active steering.

Findings

Hydrodynamic effects can explain bacterial tracking behavior.

Numerical simulations support the plausibility of the hydrodynamic hypothesis.

Flow fields influence bacterial trajectories in the model.

Abstract

Previously published experimental work by other authors has shown that certain motile marine bacteria are able to track free swimming algae by executing a zigzag path and steering toward the algae at each turn. Here, we propose that the apparent steering behaviour could be a hydrodynamic effect, whereby an algal cell's vorticity and strain-rate fields rotate a pursuing bacterial cell in the appropriate direction. Using simplified models for the bacterial and algal cells, we numerically compute the trajectory of a bacterial cell and demonstrate the plausibility of this hypothesis.