One and two-individual movements of fish after chemical exposure

Abstract

Movement behavior of an indicator species, zebrafish (Danio rerio), was analyzed with one-and two-12 individual groups before and after treatment with a toxic chemical, formaldehyde, at a low 13 concentration (1 ppm). After the boundary area had been determined based on experimental data, 14 intermittency was defined as the probability distributions of the shadowing time during which data 15 were above a pre-determined threshold and were obtained from experimental time-series data on the 16 forces and the inter-distances for one and two individuals. Overall intermittencies were similar in the 17 boundary and central areas. However, the intermittencies were remarkably different between the one-18 and the two-individual groups: the single line was used to fit the data for the one-individual group 19 whereas two phases were observed with breakpoints (approximately 10 seconds in logarithm) in the 20 exponential fitting curves for the two-individual group. A difference in the probability distributions of 21 the shadowing time was observed "before" and "after" treatment for different areas. Intermittency 22 patterns before and after treatment were contrasted in the center for the one-individual group whereas 23 2 the difference was observed in the boundary for two-individual group. The intermittencies for the inter-

Inferring variance and invariance in multi-individual behavior of zebrafish (Danio rerio) responding to chemical stress

“…It is worth noting that differences in inter-distances and time-lag effects were substantial in G2 before and after treatment (Figure 6(a) and Figure 7). The decrease in inter-distance after treatment (Figure 5(a) and Figure 6 (a)) supported the results of previous studies that showed fish were alert in the presence of low concentrations and tended to be close to neighboring individuals (Griffiths & Magurran 1997;Miller & Gerlai 2008;Quach et al 2013). In this study, we further observed that organisms tended to stay in the central area rather than in boundary or corner areas.…”

“…Although there have been numerous accounts of group behavior studies as stated above, little research has been conducted to investigate group response behaviors under chemical stress. Recently, Quach et al (2013) reported that the intermittency of the shadowing times (i.e. period over a predetermined threshold) on both forces and inter-distances for one-and two-individual groups were different before and after treatment with formaldehyde at a low concentration.…”

Reducing the Number of Individuals to Monitor Shoaling Fish Systems – Application of the Shannon Entropy to Construct a Biological Warning System Model

“…Accordingly, and given that previous studies ( Kadota et al, 2011 ; Liu et al, 2011 ; Spasic et al, 2011 ; Quach et al, 2013 ; Bae and Park, 2014 ; Eguiraun et al, 2014 , 2016 , 2018 ; Forlim and Pinto, 2014 ) have identified the SE of the system as a variable with the potential to serve for fish health and welfare monitoring, the present work was designed to understand how the variation in the fish number affects the system dynamics in order to answer the following research questions: (i) Does the SE of a fish system vary according to the number of fish? (ii) if it does vary, how is this relationship?…”

Inferring conflicting behavior of zebrafish (Danio rerio) in response to food and predator based on a self-organizing map (SOM) and intermittency test

“…However, in this study, we dealt with the boundary shapes as separate patterns. In the future, behavior processes near boundary areas should be more carefully investigated since site-specific behaviors were reported in boundaries and corners (Quach et al, 2013). …”