Effects of disinfectants, sponge densities, water circulation rates, and vibration frequency on the artificial incubation of redclaw crayfish embryos

Abstract

Artificial incubation of embryos is helpful to large-scale production of redclaw crayfish. In this study, we applied a recirculating mechanical pulling device to incubate redclaw embryos, and evaluated the effects of eco-friendly disinfectants, sponge densities, water circulation rates, and vibration frequencies on hatching % and survival % of embryos. Each factor was tested separately from the others. (1) Of the five solutions tested, a disinfectant solution comprising an essential oil base solution (1 mg/L), Zn-superoxide dismutase (SOD) 10,000 U/mg, trehalose (30 mmol/L), bovine serum protein (200 mmol/L), and astaxanthin (30 mmol/L) (solution 4) resulted in the significantly highest hatching 89.54% and survival 62.22%, which were not significantly different from the formaldehyde-treated group, but significantly higher than other treatments. It could be used as an eco-friendly, effective disinfectant for the artificial incubation of redclaw embryos instead of using traditional formaldehyde. (2) Medium density sponges with a length of 4.5 cm helped improve the survival %, it was hypothesized that the low and high density sponges were not conducive to the attachment of the newly hatched juveniles, and 5.5 cm long sponge would cause hypoxia death of juveniles. (3) Hatching 94.83%, 94.08%, and 92.58%, and survival 65.66%, 66.33%, and 67.08%, at water circulation rates of 7.1, 4.8, and 2.1 cycles/h, respectively. There was no significant difference in hatching % and survival % among groups. (4) Hatching 94.08%, 89.17%, and 91.92%, and survival 73.92%, 61.75%, and 60.50%, at vibration frequencies of 11, 16, and 26 vibrations/min, respectively. The survival % of the group exposed to 11 vibrations/min was significantly higher than at the other two frequencies. The results may have application on a large scale to improve production.