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Is circadian rhythm a good indicator in the environmental assessment? The toxic effects of contaminants in trace level on the behavior responses of goldfish (Carassius auratus)

Ren, Zongming, Ren, Baixiang, Pan, Hongwei, Li, Shangge, Ren, Baigang, Xu, Shiguo, Chon, Tae-Soo, Wang, Weiliang, Chen, Bin
Ecological indicators 2018
Carassius auratus, atrazine, autocorrelation, cadmium chloride, circadian rhythm, deltamethrin, dibutyl phthalate, environmental assessment, environmental indicators, environmental quality, goldfish, periodicity, photoperiod, surface water, toxicity, toxins, variance, China
In order to evaluate the possibility of the circadian rhythm as an indicator, the effects of contaminants on the behavior responses of goldfish (Carassius auratus) in the characteristic of behavior strength in 6 days were investigated. Circadian rhythms were characteristically observed in the exposures of 0.002 mg/L Deltamethrin (DM), 0.003 mg/L Dibutyl phthalate (DBP), 0.003 mg/L Atrazine (ATZ), and 0.003 mg/L Cadmium chloride (CdCl2) according to the Environmental Quality Standard for Surface Water of China (GB3838-2002). Data variance in both tendency analysis and Self-Organizing Map was most closely associated with photoperiods. Behavior activity (BA) effectively differentiated behavior modes according to organic compounds comparing with CdCl2. Circadian rhythm most consistently appeared after in ATZ exposure, by showing clear peaks during the light periods, being followed by CdCl2 and DM. DBP, in contrast, had no clear biorhythm with minimum fluctuation in BS curves. Totally, circadian rhythms were overall affected greatly until the second day. Auto-correlation analyses demonstrated that the affectedness by toxins would be addressed in an extra dimension in circadian rhythm. The studies on BS along with periodicity analyses and BA fitting suggest that circadian rhythm is a good indicator in the environmental assessment and contribute to broaden the scope of integrated assessments of toxic effects.