Increased metabolic cost of swimming and consequent alterations to circadian activity in rainbow trout (Oncorhynchus mykiss) exposed to dietary copper

• DOI: 10.1139/f02-046
• Publication Date: 2002-10-01T20:05:45Z
• Authors: H A Campbell; R D Handy; D W Sims
• Keywords: Diel vertical migration; Chronobiology

This study tests the hypothesis that rainbow trout (Oncorhynchus mykiss) compensate for metabolic cost of dietary Cu exposure by reducing swimming activity at particular times during diel cycle. Fish were exposed to excess three months (726 mg Cu·kg –1 dry weight) and simultaneously oxygen consumption (MO 2 ) spontaneous measured. Rhythmicity in was examined videorecording fish behaviours 48 h. Standard rate estimates (R S 7.2 8.7 mmol O ·kg ·h (15°C) measured control Cu-exposed fish, respectively. MO higher any chosen speed compared with trout, which decreased (mean speed) least 75%, spent more time lower speeds, lost circadian periodicity these parameters controls. Mean growth rates normal, although showed a narrower range body weights fewer mortalities than groups, suggesting suppression social behaviour fish. Overall, increased fully compensated reduction activity, particularly night dawn. However, this behavioural strategy suggests spatial temporal aspects ecologically important may be compromised