Effects of photoperiod on feeding habit and hepatopancreatic enzyme activity of button-sized Eriocheir sinensis

Abstract

We analyzed the effects of photoperiod on the food intake, feeding rhythm and hepatopancreatic enzyme activity in the button-sized crabs by considering three photoperiods, including full light group (24L), full darkness group (24D) and simulated natural light group (10D:14L). A total of 360 button-sized Chinese mitten crab (Eriocheir sinensis) with the weight of (10.04 ± 1.03) g were used in this study. The results showed that food intake of crabs in 10D:14L group was significantly higher than that in 24D treatment, but without difference between 24L group and the other groups. There were significant differences in food intake between 24D group and 10D:14L group during day and night. In 24L group, there was no significant difference in food intake at various time points, with the highest food intake at 10:00-13:00 and 22:00-01:00. In 24D group, there were significant differences in food intake at various time points, with the highest food intake at 01:00-04:00. In 10D:14L group, there were significant differences in food intake at various time points, and the food intake was also highest at 01:00-04:00. For hepatopancreatic enzyme activity, in 24L group, the activity of amylase and alkaline phosphatase reached the peak at 01:00 and 13:00; the activity of lipase reached the peak at 01:00; the activity of Na+ / K+-ATPase reached the peak at 04:00. The activity of amylase, lipase, Na+ / K+-ATPase and alkaline phosphatase in 24D group reached the peak at 04:00. The amylase activity in 10D:14L group reached the peak at 07:00, while that of lipase, Na+ / K+-ATPase and alkaline phosphatase reached the peak at 04:00. There was no significant difference in hepatopancreatic enzyme activity under different photoperiods. In conclusion, photoperiod affected the food intake of button-sized crabs. The button-sized crabs had an obvious feeding rhythm under the full darkness and simulated natural light. The button-sized crabs under full light had the same feeding peak as the other groups, but there was no obvious feeding rhythm, implying that the photoperiod might have no effect on the feeding rhythm of button-sized E. sinensis.