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| Titel |
A Lagrangian model of Copepod dynamics in turbulent flows |
| VerfasserIn |
Hamidreza Ardeshiri, Ibtissem Benkeddad, François G. Schmitt, Sami Souissi, Federico Toschi, Enrico Calzavarini |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122747
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| Publikation (Nr.) |
 EGU/EGU2016-1856.pdf |
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| Zusammenfassung |
| Planktonic copepods are small crustaceans that have the ability to swim by quick powerful
jumps. Such an aptness is used to escape from high shear regions, which may be
caused either by flow perturbations, produced by a large predator such as fish larave,
or by the inherent highly turbulent dynamics of the ocean. Through a combined
experimental and numerical study, we investigate the impact of jumping behaviour
on the small-scale patchiness of copepods in a turbulent environment. Recorded
velocity tracks of copepods displaying escape response jumps in still water are
used to define and tune a Lagrangian Copepod (LC) model. The model is further
employed to simulate the behaviour of thousands of copepods in a fully developed
hydrodynamic turbulent flow obtained by direct numerical simulation of the Navier-Stokes
equations. First, we show that the LC velocity statistics is in qualitative agreement
with available experimental observations of copepods in turbulence. Second, we
quantify the clustering of LC, via the fractal dimension D2. We show that D2 can
be as low as 2.3, corresponding to local sheetlike aggregates, and that it critically
depends on the shear-rate sensitivity of the proposed LC model. We further investigate
the effect of jump intensity, jump orientation and geometrical aspect ratio of the
copepods on the small-scale spatial distribution. Possible ecological implications
of the observed clustering on encounter rates and mating success are discussed. |
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