title: Multifractal anisotropic swimming: the optimal foraging behaviour of grouper larvae.
abstract: It was hypothesized that the Malabar grouper Ephinephelus malabaricus larvae have developed search patterns adapted to the distribution of their prey to maximise their net energy intake per unit time. Analysis of the swimming behaviour of E. malabaricus larvae in both the presence and absence of Artemia sp. nauplii is presented to test this hypothesis. A method derived from turbulence studies (the moment function of the displacements) was used to characterize the behaviour. The results revealed that larval swimming pattern was multifractal (intermittent and long-range-correlated) and isotropic (i.e. uniform in all directions) in the presence of prey, but multifractal and anisotropic (i.e. more frequent long displacement on the vertical axis) in the absence of prey. It is suggested that the search behaviour observed in the absence of prey is an adaptive response to prey distribution pattern, which is often characterised by multifractality and anisotropy (i.e. larger patches on the horizontal axes). In the presence of prey, E. malabaricus shifted to intensive search behaviour. Other possible contributors to the observed patterns are discussed. It is concluded that multifractality and anisotropy of swimming patterns observed in the experiment are mainly explained in an optimal foraging theory framework.
authors.affiliation: Univ. Lille, CNRS, Univ. Littoral Cote d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F 62 126 Wimereux, France.|Institute of Marine Biology, National Taiwan Ocean University, 202 Keelung, Taiwan.
authors.forename: M S
authors.initials: MS
authors.lastname: Mahjoub
authors.affiliation: Institute of Marine Biology, National Taiwan Ocean University, 202 Keelung, Taiwan.
authors.forename: G
authors.initials: G
authors.lastname: Dur
authors.affiliation: Univ. Lille, CNRS, Univ. Littoral Cote d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F 62 126 Wimereux, France.
authors.forename: S
authors.initials: S
authors.lastname: Souissi
authors.affiliation: Univ. Lille, CNRS, Univ. Littoral Cote d'Opale, UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, F 62 126 Wimereux, France.
authors.forename: F G
authors.initials: FG
authors.lastname: Schmitt
authors.affiliation: Institute of Marine Biology, National Taiwan Ocean University, 202 Keelung, Taiwan.
authors.forename: J S
authors.initials: JS
authors.lastname: Hwang
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D016880:Anisotropy; D002149:Energy Intake; D005247:Feeding Behavior; D007814:Larva / Q000502:physiology; D010473:Perciformes / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology; D013550:Swimming
keywords: feeding; fish larva; multifractality; plankton