Turbulence drives microscale patches of motile phytoplankton

Durham, William M.; Climent, Éric; Barry, Michael; Lillo, F. De; Boffetta, G.; Cencini, Massimo; Stocker, Roman

doi:10.1038/ncomms3148

Cited by 275 publications

(329 citation statements)

References 51 publications

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“…In dinoflagellates, bloom formation typically occurs at low mixing and water column stratification [26]. Under such conditions, plankton populations are often not homogeneously distributed, but rather show a spatially structured distribution, for instance as patches or thin layers [2][3][4]72]. Flagellar movement may favour accumulation in patches [72], which is presumably also required for sexual reproduction in the life cycle of Alexandrium [17], as increased encounter rates in patches may allow Alexandrium gametes to find their corresponding mating type [73].…”

Section: Discussionmentioning

confidence: 99%

“…The functioning of allelochemical mediated facilitation in natural populations will thus depend on the degree of spatial dispersal, i.e. the local accumulation of a population, as well as on the rate at which extracellular allelochemicals are produced and excreted, and on the rate of their diffusion and degradation [51,72]. In dinoflagellates, bloom formation typically occurs at low mixing and water column stratification [26].…”

Section: Discussionmentioning

confidence: 99%

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Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population

et al. 2015

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Dinoflagellates are a major cause of harmful algal blooms (HABs), with consequences for coastal marine ecosystem functioning and services. Alexandrium fundyense (previously Alexandrium tamarense) is one of the most abundant and widespread toxigenic species in the temperate Northern and Southern Hemisphere and produces paralytic shellfish poisoning toxins as well as lytic allelochemical substances. These bioactive compounds may support the success of A. fundyense and its ability to form blooms. Here we investigate the impact of grazing on monoclonal and mixed set-ups of highly (Alex2) and moderately (Alex4) allelochemically active A. fundyense strains and a non-allelochemically active conspecific (Alex5) by the heterotrophic dinoflagellate Polykrikos kofoidii. While Alex4 and particularly Alex5 were strongly grazed by P. kofoidii when offered alone, both strains grew well in the mixed assemblages (Alex4 þ Alex5 and Alex2 þ Alex5). Hence, the allelochemical active strains facilitated growth of the non-active strain by protecting the population as a whole against grazing. Based on our results, we argue that facilitation among clonal lineages within a species may partly explain the high genotypic and phenotypic diversity of Alexandrium populations. Populations of Alexandrium may comprise multiple cooperative traits that act in concert with intraspecific facilitation, and hence promote the success of this notorious HAB species.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population

et al. 2015

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“…Recent works have shown that gyrotaxis also produces clustering at very small scales (comparable with the Kolmogorov scale) in nonstationary turbulent flows [17][18][19][20]. In this case cells are found to accumulate on fractal dynamical clusters characterized by a fractal dimension which depends on the cell and flow parameters [17,18,21].…”

Section: Introductionmentioning

confidence: 99%

Scale-dependent colocalization in a population of gyrotactic swimmers

2017

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We study the small scale clustering of gyrotactic swimmers transported by a turbulent flow, when the intrinsic variability of the swimming parameters within the population is considered. By means of extensive numerical simulations, we find that the variety of the population introduces a characteristic scale R * in its spatial distribution. At scales smaller than R * the swimmers are homogeneously distributed, while at larger scales an inhomogeneous distribution is observed with a fractal dimension close to what observed for a monodisperse population characterized by mean parameters. The scale R * depends on the dispersion of the population and it is found to scale linearly with the standard deviation both for a bimodal and for a Gaussian distribution. Our numerical results, which extend recent findings for a monodisperse population, indicate that in principle it is possible to observe small scale, fractal clustering in a laboratory experiment with gyrotactic cells.

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“…They show that coupling gyrotactic motion to turbulent flow produces small-scale patchiness (smaller than the Kolmogorov scale) in the swimmer distribution. Durham (2012); Durham et al (2013) also examined whether gyrotaxis can generate cell patchiness in turbulent flow using experiments and numerical simulations. They found that accumulation in downwelling regions is the dominant means of aggregation also in turbulent flow and shows that patchiness is not significantly affected by the Taylor Reynolds number Re λ .…”

Section: Introductionmentioning

confidence: 99%

Accumulation of motile elongated micro-organisms in turbulence

et al. 2013

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We study the effect of turbulence on marine life by performing numerical simulations of motile microorganisms, modelled as prolate spheroids, in isotropic homogeneous turbulence. We show that the clustering and patchiness observed in laminar flows, linear shear and vortex flows, are significantly reduced in a three-dimensional turbulent flow mainly because of the complex topology; elongated micro-orgamisms show some level of clustering in the case of swimmers without any preferential alignment whereas spherical swimmers remain uniformly distributed. Micro-organisms with one preferential swimming direction (e.g. gyrotaxis) still show significant clustering if spherical in shape, whereas prolate swimmers remain more uniformly distributed. Due to their large sensitivity to the local shear, these elongated swimmers react slower to the action of vorticity and gravity and therefore do not have time to accumulate in a turbulent flow. These results show how purely hydrodynamic effects can alter the ecology of microorganisms that can vary their shape and their preferential orientation.

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Turbulence drives microscale patches of motile phytoplankton

Cited by 275 publications

References 51 publications

Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population

Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population

Scale-dependent colocalization in a population of gyrotactic swimmers

Accumulation of motile elongated micro-organisms in turbulence

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