Volume 80, Number 6, December 2007
Article Number 60003
Number of page(s) 5
Section General
Published online 06 November 2007
EPL, 80 (2007) 60003
DOI: 10.1209/0295-5075/80/60003

The influence of search strategies and homogeneous isotropic turbulence on planktonic contact rates

C. J. Rhodes1 and A. M. Reynolds2

1  Institute for Mathematical Sciences, Imperial College London - 53 Prince's Gate, Exhibition Road, South Kensington, London, SW7 2PG, UK
2  Rothamstead Research - Harpenden, Hertfordshire, AL5 2JQ, UK

received 4 August 2007; accepted in final form 15 October 2007; published December 2007
published online 6 November 2007

Many species have been shown to adopt a Lévy-flight pattern of movement which are consistent with the most efficient way to locate sparsely distributed targets. Here, we consider a predator that conducts its search for prey in a turbulent environment. Such a situation is relevant to zooplankton-phytoplankton ecosystems. Kinematic simulation is used to represent the turbulent velocity field in the surface layers of the open ocean and contact with the prey is maximised for a predator swimming a Lévy flight with an exponent $\mu \simeq$ 1.2. The contact rate exceeds that recorded during straight-line swimming and passive advection. The observation that the contact rate is maximised for $\mu \simeq$ 1.2 appears to be not strongly dependent on predator swimming speed. The results are discussed in the context of recent work on planktonic search in laboratory conditions where Lévy-flight exponents of $\mu \simeq$ 2 were noted.

02.50.Ey - Stochastic processes.
05.20.Jj - Statistical mechanics of classical fluids.
05.40.Fb - Random walks and Lévy flights.

© Europhysics Letters Association 2007