Individual variability in the swimming behavior of the sub-tropical copepod Oncaea venusta (Copepoda: Poecilostomatoida)

Abstract

The swimming behavior of males and females of the seldom studied sub-tropical copepod Oncaea venusta was studied using scale-dependent (swimming speed and net-to-gross displacement ratio) and scale-independent (fractal dimension) metrics. The scale-dependent metrics were characterized by: (1) a considerable intra-and inter-individual variability that prevented the identification of any specific behavior and (2) a strong dependence on the number of data points available in each individual path. Conversely, the scale-independent metric (fractal dimensional) resolved reduced intra-and inter-individual variability and independence from the length of the swimming paths, leading to the identification of 4 groups of distinct swimming patterns. While additional behavioral experiments are needed to ensure the relevance and the generality of the present results, behavioral fractal analysis nevertheless demonstrates a promising ability to elucidate the complexity of zooplankton behavior.KEY WORDS: Zooplankton · Swimming · Behavior · Scale-dependence · Scale-independence · Fractal · ScalingResale or republication not permitted without written consent of the publisher

Increased seawater viscosity, Phaeocystis globosa spring bloom and Temora longicornis feeding and swimming behaviours

“…As discussed elsewhere (Seuront et al 2004), all of these metrics are implicitly a function of their measurement scale, and there is no single scale at which swimming paths can be unambiguously described. This is not the case for fractal dimensions, which are scale-independent.…”

“…This is not the case for fractal dimensions, which are scale-independent. However, because fractal dimensions have seldom been used in zooplankton behavioural studies (see Seuront et al 2004 for a review), more common behavioural measures were also used to provide a reference framework for the reader to make comparisons with previous studies having similar temporal resolution.…”

“…Swimming paths may be characterised by a variety of measures, including for example path length (the total distance travelled, or gross displacement), move length (the distance travelled between consecutive points in time), move duration (the time interval between successive locations), turning angle (the difference in direction between 2 successive moves), turning rate (the turning angle divided by move duration) and net displacement (the linear distance between starting and ending point); see Seuront et al (2004) for a review. As discussed elsewhere (Seuront et al 2004), all of these metrics are implicitly a function of their measurement scale, and there is no single scale at which swimming paths can be unambiguously described.…”

“…This dimension D b is estimated from the slope of the linear trend of the plot of logN(λ) versus log λ. Because slight reorientation of the overlying grid can produce different values of N (λ), the fractal dimensions D b have been estimated for rotation of the initial 2D grid of 5°increments from 0 to 45° (Seuront et al 2004). …”

Role of kairomones in host location of the pennellid copepod parasite, Lernaeocera branchialis (L. 1767)

“…Fractal dimensions were calculated using the 'box counting' method (Seuront et al 2004;Uttieri et al 2007). This method finds the number of boxes of length λ required to cover the track by superimposing a regular grid of boxes of length λ onto the image and counting the number of occupied boxes.…”