Centripetal focusing of gyrotactic phytoplankton

M Cencini; M Franchino; F Santamaria; G Boffetta

doi:10.1016/j.jtbi.2016.03.037

Centripetal focusing of gyrotactic phytoplankton

J Theor Biol. 2016 Jun 21:399:62-70. doi: 10.1016/j.jtbi.2016.03.037. Epub 2016 Apr 7.

Authors

M Cencini¹, M Franchino², F Santamaria³, G Boffetta⁴

Affiliations

¹ Institute of Complex Systems-CNR, via dei Taurini 19, 00185 Rome, Italy.
² Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123 Torino, Italy.
³ Department of Physics and INFN, University of Torino, via P.Giuria 1, 10125 Torino, Italy.
⁴ Department of Physics and INFN, University of Torino, via P.Giuria 1, 10125 Torino, Italy. Electronic address: guido.boffetta@unito.it.

PMID: 27060672
DOI: 10.1016/j.jtbi.2016.03.037

Abstract

A suspension of gyrotactic microalgae Chlamydomonas augustae swimming in a cylindrical water vessel in solid-body rotation is studied. Our experiments show that swimming algae form an aggregate around the axis of rotation, whose intensity increases with the rotation speed. We explain this phenomenon by the centripetal orientation of the swimming direction towards the axis of rotation. This centripetal focusing is contrasted by diffusive fluxes due to stochastic reorientation of the cells. The competition of the two effects lead to a stationary distribution, which we analytically derive from a refined mathematical model of gyrotactic swimmers. The temporal evolution of the cell distribution, obtained via numerical simulations of the stochastic model, is in quantitative agreement with the experimental measurements in the range of parameters explored.

Keywords: Fluid-flow motility interaction; Gyrotaxis; Microorganism motility.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomechanical Phenomena
Chlamydomonas / physiology
Computer Simulation
Phytoplankton / physiology*
Rotation*
Time Factors