Effects of artificial substrates on the growth and immunology of postlarvae of Marsupenaeus japonicus (Spence Bate, 1888) (Decapoda: Dendrobranchiata: Penaeidae) reared in biofloc

Abstract

Abstract We investigated the effects of biofloc and artificial substrates (net and brush) on the growth and immunology of the postlarvae of Marsupenaeus japonicus (Spence Bate, 1888) reared for 30 days. The mRNA expressions of innate immune-related genes (prophenoloxidase, masquerade-like serine proteinase, and lysozyme) in the postlarvae were analyzed using quantitative reverse transcription PCR (qRT-PCR). The highest specific growth rate of larvae (3.66 ± 0.02% d–1, 3.75 ± 0.02% d–1) were shown in the net and control groups. The highest survival rate (90 ± 7.1%) was observed in the brush group (P < 0.05). The net yield was significantly higher in the artificial substrate groups (brush 36.60 ± 6.19 g m–2, net 36.46 ± 2.36 g m–2) than in the control (33.79 ± 0.16 g m–2) (P < 0.05). Total suspended, volatile suspended, and suspended solids were significantly lower in the brush group than in the other groups. The immune-related genes showed significantly higher expressions in the artificial substrate groups than in the control. These results support the benefits of artificial substrate in M. japonicus nursery culture to mitigate space competition and suppress cannibalism, with a positive effect on survival. The additional surface area provided by the biofloc, which the larvae can graze on, enhanced the expression of immune-related genes in individuals.