Motion of dinoflagellates in a simple shear flow

Abstract

Turbulence can be highly significant to dinoflagellates by affecting their swimming motion. We examined the effects of simple shear flow on swimming trajectories and orientations of two species of dinoflagellates Glenodinium foliaceum and Alexandrium catenella. In the absence of either shear or a cue that can cause directional motion, swimming orientations of both species were insignificantly different from random. Although cells of G. foliaceum maintained their random swimming orientations upon exposure to shear, swimming orientations of both single cells and chains of A. catenella were affected by shear. Magnitude of the effect increased with shear rate. Changes in decorrelation times, as a result of exposure to shear, were observed for both species, providing another indication that shear affects swimming behavior. Decorrelation times for the swimming directions of both species were of the same order as the characteristic time scale of turbulence that would produce shear rates comparable to those examined in this study. Theoretical models that assess the effects of turbulence on vertical migration of dinoflagellates and predator-prey interactions commonly assume that swimming motion of dinoflagellates in the presence of shear flow can be described by simple superposition of the flow on the swimming motion in the absence of flow. Our results suggest that this assumption is not universally true.

Shear-induced orientational dynamics and spatial heterogeneity in suspensions of motile phytoplankton

“…This offset does not occur for deterministic Jeffery orbits (figure 3g) and is, in fact, a hallmark of the competition between rotational diffusion and shear, previously observed in colloidal suspensions [51] and bacteria [10], which is usually expressed by the rotational Péclet number, Pe R ¼ S=D R . As confirmed by our observations, this offset is stronger at low flow rates ðPe R 1Þ A similar offset in peak orientation also occurred in a previous experiment that tested the response of dinoflagellates to shear rates characteristic of oceanic turbulence in a Couette flow [34]. In line with experiments conducted here at similarly low shear rates, many of the orientation distributions reported in that study were uniform.…”

Sex and flow: the consequences of fluid shear for sperm–egg interactions

“…At low shears, cumulative effects of active cell behavior, such as chemotaxis, would enhance cell contacts and fertilization rate (Karp-Boss et al, 2000;Soghomonians et al, 2002;Smith et al, 2007). At high shears, near-cell (<20·m) hydrodynamics induce gametes to rotate, and disassociate, thus accelerating a decline in gamete encounters and fertilization rate (Kiørboe and Titelman, 1998).…”

“…Specialized flow chambers, such as the Taylor-Couette apparatus (Bartok and Mason, 1957;Goldsmith and Marlow, 1972;Karp-Boss and Jumars, 1998;Ameer et al, 1999), cone-and-plate viscometer (Highgate and Whorlow, 1970;Solomon and Boger, 1998) and many types of microfabricated devices (Dellimore, 1976;Meng et al, 2005), have enabled studies of flow and particle interactions. Several results have shown that flow dominates behavior and cells are transported like passive particles (Rossman, 1937;Happel and Brenner, 1965;Shimeta et al, 1995;Karp-Boss et al, 2000;Dombrowski et al, 2004). Shear induced, for example, leukocyte tumbling under hydrodynamic conditions that typify the blood flow of mammalian arteries and veins (Cinamon et al, 2001;Goldsmith et al, 2001;Kadash et al, 2004).…”

Flexibility of bacterial flagella in external shear results in complex swimming trajectories

“…In Kessler [32], the gyrotaxis effect in biflagellated swimming algae was described. Karp-Boss et al [33] demonstrated that the differences in drag forces between body and flagella lead to preferential alignment with the flow. Recent experiments suggest that rheotaxis may significantly affect the navigation of mammalian sperm cells [18,19].…”