Lead effects on the predictability of reproductive behavior in fathead minnows (Pimephales promelas): A mathematical model

Abstract

Lead (Pb) has been shown to affect the behavior of a wide variety of vertebrates, including fish, amphibians, and mammals. This article re-examines previous data on the effect of short-term, sublethal levels of waterborne Pb on the reproductive behavior of fathead minnows (Pimephales promelas). Previous research has found that Pb decreased the time spent in displaying specific reproductive behaviors in male minnows. Because each activity performed within a sequence depends upon previous parts of the sequence, the reproductive behavior of fish is not randomly distributed but is presented as a long-range self-similar correlation. By treating these data as a fractal dimension, it is now possible to determine changes in the long-term correlation of different behavioral sequences involved in nest maintenance owing to Pb exposure (0.5 ppm Pb as Pb acetate), both before and after adult males attain reproductive maturity. We hypothesized that the scaling exponent of this fluctuation varies in relation with environmental contaminants. Known Pb-induced changes in hormonal activity may account for changes in observed reproductive and nest maintenance behaviors. Pb-exposed fish exhibited higher levels of predictability (less complexity) in their behavioral sequences, i.e., they demonstrated an increase in the scaling parameter of the fluctuation a. However, if Pb was introduced after sexual maturity was observed, there was no significant difference in the scaling component a. Thus, the use of fractal dimension may provide a useful tool to analyze the effects of environmental contaminants and other stresses.

Modeling activity patterns of wildlife using time‐series analysis

“…The autocorrelation properties of animal activity patterns are interesting to study because they may reflect differences in physiological states of animals and their responses to environmental factors in new ways (MacIntosh, Alados, & Huffman, ; MacIntosh, Pelletier, Chiaradia, Kato, & Ropert‐Coudert, ). For example, some studies have shown that physiological stressors (e.g., clinically impaired health, reproductive activities) or other challenges (e.g., low dominance status) are associated with less stochasticity, that is, increasing periodicity or stereotypy (Alados & Weber, ; Alados et al., ; Motohashi, Miyazaki, & Takano, ; Rutherford, Haskell, Glasbey, & Lawrence, ; Seuront & Cribb, ). In contrast, individuals show increased complexity of behavioral patterns when they explore resources in novel environments, which in turn may increase foraging success rates (Alados et al., ; Escos et al., ; Kembro et al., ; MacIntosh et al., ; Shimada, Minesaki, & Hara, ).…”

Fractal analysis of behaviour in a wild primate: behavioural complexity in health and disease

“…We repeated this procedure for all time scales (box sizes), which were the nearest integers to 2 Previous studies show that a-exponents (described in §1) of observed behavioural sequences differ significantly from randomized surrogate sequences, which result in a % 0.5 [17,19]. We randomized 78 foraging and 85 locomotion sequences collected during October and November 2007, and compared the mean a-exponents of 10 simulated sequences with observed sequences using paired t-tests.…”

Dispersal abilities and spatial patterns in fragmented landscapes

“…The long‐range spatial autocorrelation of each species determined the degree of spatial clustering of each species' cover, independent of the scale of measurement. Detrended fluctuation analysis (DFA), which describes spatial autocorrelation and patchiness, as opposed to random distribution, was used to detect long‐range spatial autocorrelations (Peng et al ., 1992; Alados & Weber, 1999; Hu et al ., 2001). A large DFA value indicates that what happens in one step depends on what appears in previous consecutive steps across a long sequence.…”