Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 41: Microswimmers II (Joint Session with DY)
BP 41.2: Vortrag
Mittwoch, 9. März 2016, 11:45–12:00, H45
Escaping turbulence? Phytoplankton use active shape control to rapidly adapt swimming strategies — •Anupam Sengupta1,2, Francesco Carrara1, and Roman Stocker2 — 1Massachusetts Institute of Technology, 15 Vassar Street, Cambridge MA 02139, USA — 2ETH Zurich, Institute for Environmental Engineering, Stefano-Franscini-Platz 5, 8093 Zurich, Switzerland
Turbulence has long been known to affect phytoplankton fitness and species succession, yet, a mechanistic view of how turbulence affects phytoplankton migration has been lacking. Here we report on the first observations demonstrating that phytoplankton can actively respond to turbulence-like cues. Using the red-tide producing species Heterosigma akashiwo as a model system, we show that hydrodynamic cues mimicking overturning by Kolmogorov-scale turbulent eddies trigger a diversification in the migration behavior. Upon exposure to repeated overturning, an originally upward swimming population robustly splits in two equi-abundant subpopulations, one swimming upward and one swimming downward. Quantitative image analysis at the single-cell level showed that the behavioral switch was accompanied by a rapid morphological change at the sub-micrometer scale, and a mathematical model of the cell's mechanical stability confirms that this shape change can flip the swimming direction and ultimately induce downward migration. The results indicate that certain phytoplankton species may have evolved subtle strategies to actively change their migratory behavior in response to turbulent cues, possibly a bet-hedging strategy to escape from turbulent microzones in the ocean.