| Paralichthys olivaceus has become an economically important target species for marine aquaculture due to its large size, rapid growth rate, excellent meat quality, rich nutritional value and short-distance migratory habit. The industrial farming model has been widely used due to its high degree of intensification and environmental controllability. In this mode, artificial lighting is commonly used in factory farming to meet the farming needs. Compared with the traditional artificial lighting of straight tube fluorescent lamps or compact fluorescent lamps, LED lamps not only have the advantages of energy saving and environmental protection, long service life, low heat generation and high photoelectric conversion efficiency, but also have the ability to accurately regulate the spectrum and intensity of light according to the demand, which has been rapidly promoted in the factory farming. Different light-colour environments has a certain degree of inhibitory or promotional effects on the growth, physiological and biochemical processes, and stress responses of aquatic organisms. In this study, A total of 450 individuals with good body condition and uniform body size were selected, with a mean body mass of (309.66 ± 32.73) g and an initial total length of (28.67 ± 2.66) cm. Five LED spectral parameters were set, which were red (λ 625~630 nm), yellow (λ 570~575 nm), blue (λ 450~455 nm) and green (λ 525~530 nm), and full spectrum (λ380~780 nm) as the control group. water temperature was controlled at (18.0±1.0)℃, photoperiod was 12L:12D. The light intensity was set at (250 ± 20) mW/m2. Five different light colors on the growth, enzyme activity, hormone and gene expression of juvenile Paralichthys olivaceus were studied. The enzyme activities included two antioxidant enzymes, SOD and CAT , and two digestive enzymes, amylase and fibrillase, the hormones included growth hormone and cortisol, and the genes were mainly SOD and CAT. The aim was to provide theoretical support for the selection of light color for juvenile Paralichthys olivaceus in factory farming. The results showed that the weight gain rate and specific growth rate of juvenile Paralichthys olivaceus in the blue light groups and green light groups were significantly higher than the others (P < 0.05). The growth hormone content of juvenile Paralichthys olivaceus in the red light group was the lowest at 10.68±0.61 ng/mL, which was significantly lower than that of other groups (P < 0.05), while the cortisol content was the highest at 1487.44±54.42 pg/mL, which was significantly higher than that of other groups (P < 0.05). The growth hormone content of juvenile Paralichthys olivaceus in the blue light group was the highest at 20.74±1.52 ng/mL, which was significantly higher than that of other groups (P < 0.05). The gastric amylase activity of juvenile Paralichthys olivaceus in the green light group was significantly higher than that of the red light group and the control group (P < 0.05). The gastric cellulase activity of juvenile Paralichthys olivaceus in the red light group was significantly lower than that of the control group (P < 0.05). The intestinal cellulase activity of juvenile Paralichthys olivaceus in the red light group was significantly lower than that of the other groups (P < 0.05). In the red light, the CAT activity in the serum of juvenile Paralichthys olivaceus in the red light group was significantly lower than that of other groups (P < 0.05), and the liver CAT activity was significantly lower than that of the control group (P < 0.05). The differences in liver SOD activity of juvenile Paralichthys olivaceus in each light colour group were not significant (P > 0.05). The relative expression of liver SOD gene of juvenile Paralichthys olivaceus in the red light group was significantly lower than that in the yellow light group (P < 0.05), but the difference with other groups was not significant; the relative expression of CAT genes in the liver of juvenile Paralichthys olivaceus in the red light group was the lowest and significantly lower than that in the other groups (P < 0.05), the relative expression of liver CAT gene of juvenile Paralichthys olivaceus in the yellow light group was the highest and significantly higher than that in the other groups (P < 0.05), and the relative expression of CAT gene of juvenile Paralichthys olivaceus in the blue light group, green light group and control group was not significant. The results showed that blue and green light culture significantly affected the growth of juvenile Paralichthys olivaceus, while red light continuously stressed juvenile Paralichthys olivaceus weakening their antioxidant and digestive capacities. The results provide a theoretical basis for improving indoor factory aquaculture efficacy of juvenile Paralichthys olivaceus and promote green healthy factory aquaculture of juvenile Paralichthys olivaceus in factories. |
