| Light environment is one of the most important environmental factors in aquaculture production.It plays an irreplaceable role in regulating the growth,behavior and feeding of aquatic organisms and realizing high quality and efficient production.Factory farming has the advantages of high intensity,strong controllability and little influence of external environment.It is one of the important directions of aquaculture development in the future.For the reason of the hot insulation and stable structure,the indoor factory farming workshop is relatively closed.Compared with the traditional open farming modes such as ponds and cages,one of the more intuitive differences is the isolation or blocking of natural light.The development of alternative light source and the application of lighting strategy are particularly signification.Compared with traditional light source,LED light source has the advantages of high photoelectric conversion efficiency,high light utilization rate,strong controllability,long life and better energy saving effect.Replace traditional incandescent lamp,fluorescent lamp to serve as fill light source,its advantage is remarkable.Litopenaeus vannamei is the main species of prawn cultivation in China.In recent years,its factory farming model has been rapidly popularized,but the light environment control strategy of the factory farming model of the prawns has not been established yet.The propagation law of specific light source in aquaculture water and its effect on the growth and stress response of prawns are still unclear.In this study,underground deep well seawater and Litopenaeus vannamei factory aquaculture workshop were used to simulate the aquaculture water environment.Through the development of measuring equipment and the statistical analysis of data by direct measurement method,the propagation law of LED light source with different spectral components in aquaculture environment was summarized;The growth and antioxidant enzyme activity of Litopenaeus vannamei under ultraviolet radiation were measured;To explore the effect of different photochromic environments on the growth and antioxidant enzyme activity of Litopenaeus vannamei.It is expected to provide a scientific reference for the research on the photobiological effects of indoor factory mariculture animals and the construction of the optimal control strategy of indoor factory farming light environment.1.Analysis of propagation characteristics of LED light source in aquaculture waterThe transmittance of five different LED light sources decreases with the increase of water depth.The variation trends of different light sources were different.When the water depth was 10 cm,the green light show the largest transmittance(46.01±4.03%),UVA show the lowest value(26.01±2.53%).When the water depth was 150 cm,the light transmittance of all five kinds of light sources were less than 1.5%.The attenuation curves of light transmittance in water of five different light colors all accord with power function.The absorption of LED lights by water were discrepant in different spectral regions and has obvious selectivity.Most of the infrared and ultraviolet parts of the spectrum were absorbed by water.The absorption of the red,yellow and green spectrum in the visible spectrum band is also significant.LED light is seriously attenuated in aquaculture water,and water depth is the main factor affecting LED light propagation(P<0.01),followed by TSS and COD.However,the extent to which different light sources are affected by TSS and COD content in aquaculture water is different.2.Effects of ultraviolet light on growth and antioxidant activity of Litopenaeus vannameiSpecific growth rate(SGR)was significantly different in different light environment groups.The total spectrum +UVA group had the highest SGR,followed by the total spectrum +UVB group and the total spectrum group,and the dark group had the lowest SGR(P<0.05).Feed conversion efficiency(FCE)of full spectrum +UVA group was significantly higher than that of other groups(P<0.05).There was no significant difference in Feeding intake(FI)between groups.The results showed that the content of superoxide dismutase(SOD)in liver and pancreas of prawn was increasing in the light group,but decreased in the dark group.At the end of the experimental period,SOD activity of shrimp in the full spectrum+UVA group was significantly higher than that in the full spectrum +UVB group and the dark group(P<0.05),while that in the light group was significantly higher than that in the dark group(P<0.05).At the end of the experiment,the changes of catalase(CAT),glutathione peroxidase(GSH-Px),total antioxidant activity(T-AOC)and alkaline phosphatase(ALP)in different experimental groups were similar to SOD,with a better law to follow.MDA content of prawns in the full spectrum group decreased first and then increased.MDA contents in the full spectrum+UVA group and the full spectrum +UVB group were maintained at a relatively stable level.MDA content in the dark group was significantly higher than that in the light group at the middle and end of the experiment,and MDA content gradually increased during the experiment,indicating a higher potential oxidative damage in the body.The results showed that the growth and antioxidant enzyme activity of the full spectrum+UVA group was more suitable for the growth of Litopenaeus vannamei than that of the full spectrum +UVB group.The dark group suffered more serious oxidative damage and was not suitable for the growth of Litopenaeus vannamei.3.Effects of light color on growth and antioxidant activity of Litopenaeus vannameiThe light environment has a significant influence on SGR,FCE and FI of the Litopenaeus vannamei.The full spectrum group had the highest SGR,significantly higher than the green light group and yellow light group,followed by the blue light group and red light group,and the lowest in the dark group(P<0.05).FCE of the full spectrum group and the green light group was significantly higher than that of the yellow light group,the red light group and the blue light group,with the lowest in the dark group(P<0.05).FI in the full spectrum group was significantly higher than that in the yellow group,the dark group,the green group and the blue group,with the lowest in the red group(P<0.05).The detection results of physical and chemical indexes showed that SOD?CAT?GSH-Px?T-AOC?ALP and PO were the most active and MDA content was the lowest in the whole spectrum group compared with other experimental groups(P<0.05).In the monochromatic light source,the activity of SOD,CAT,GSH-Px,T-AOC and ALP of prawns in the green light group was higher than other monochromatic light groups,and MDA content was lower than that of other monochromatic light groups(P<0.05).Compared with the light group,the six antioxidant related enzymes of prawn in the dark group showed the lowest activity,while MDA content was higher(P<0.05).The experimental results showed that the growth and antioxidant enzyme activity of prawn was better under full spectral light,which was suitable for the growth of Litopenaeus vannamei.In the monochromatic light source,the green light source is preferred to be used as the supplementary light source for Litopenaeus vannamei aquaculture.The dark environment is not suitable for the growth of Litopenaeus vannamei. |
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