The Effects of Different UVA Photoperiods on the Growth Performance, Immune Responses, Antioxidant Status and Apoptosis-Related Gene Expression of the Pacific White Shrimp (Penaeus vannamei)

Abstract

UVA is the most common type of solar UV radiation in aquatic environments; however, the effects it causes in shrimp farming in recirculating water systems (RAS) is unclear. Thus, the growth performance, immune responses, antioxidant status and apoptosis-related gene expression in Pacific white shrimp, Penaeus vannamei (body weight 9.56 ± 0.10 g), reared with 12L: 12D full spectrum light as background light under five UVA (peak at 400 nm) photoperiods (0L: 24D, 2L: 22D, 4L: 20D, 8L: 16D and 12L: 12D) at a light intensity of 1 W/m2 were investigated. The results showed that the 2L: 22D and 4L: 20D UVA photoperiods enhanced the growth performance and reduced the feed conversion ratio and the shrimp mortality. Shrimp exposed to UVA (2L: 22D and 4L: 20D) also displayed higher levels of hepatopancreas catalase (CAT), superoxide dismutase (SOD), acid phosphatase (ACP), phenol oxidase (PO) and lysozyme (LZM) compared to the 8L: 16D and 12L: 12D groups. The malondialdehyde (MDA) levels increased in line with the extension of the UVA irradiation time. The mRNA expression of apoptosis-related genes in all the UVA treatments were significantly higher than with the control treatment, except for the 2L: 22D group. The results of the 2L: 22D and 4L: 20D treatments were significantly higher than those of the control group, except for LGBP. In conclusion, 2L: 22D and 4L: 20D UVA photoperiods increased growth performance and decreased FCR, improved the innate immunity and antioxidant response and reduced the mortality rate in adult shrimp.

Effects of Photoperiod on Survival, Growth, Physiological, and Biochemical Indices of Redclaw Crayfish (Cherax quadricarinatus) Juveniles

“…Crustaceans are different from vertebrates because they lack acquired specific immune functions but possess a robust nonspecific immune system that swiftly identifies and effectively clears invading microorganisms [16]. LZM, an antimicrobial peptide, primarily protects the stability of organisms by hydrolyzing the cell walls of Gram-positive bacteria and removing foreign harmful substances.…”

“…The response of animals to changes in external light conditions involves complex physiological and biochemical processes, and various biochemical substances [14][15][16]. Among these substances, melatonin (N-acetyl-5-methoxy-tryptamine) plays a vital regulatory role in the circadian rhythms of animals [17].…”

“…The rhythmic secretion of melatonin by Chinese mitten crab (Eriocheir sinensis) and the crab (Neohelice granulate) can be disrupted under constant light conditions [15,18]. Furthermore, as a stressor, drastic changes in photoperiod can cause crustaceans to produce a series of responses, which cause variations in reactive oxygen species (ROS) levels and lead to oxidative stress and negative impacts [16,19]. Cortisol is an essential indicator of internal environmental stability in crustaceans.…”

“…For example, mud crab (Scylla paramamosain) juveniles under daily 18 h light conditions have a higher cortisol level and the lowest survival rate compared to other photoperiod groups [20]. Moreover, changes in photoperiod could lead to variations in the secretion levels of antioxidant enzymes and immune factors among crustaceans [16,19]. For example, the superoxide dismutase (SOD) activity of giant freshwater prawn (Macrobrachium rosenbergii) decreases with a decrease in daylight exposure, whereas lysozyme (LZM) activity increases with an increase in daylight exposure [21].…”

“…For example, the superoxide dismutase (SOD) activity of giant freshwater prawn (Macrobrachium rosenbergii) decreases with a decrease in daylight exposure, whereas lysozyme (LZM) activity increases with an increase in daylight exposure [21]. Acid phosphatase (ACP) activity in pacific white shrimp (Penaeus vannamei) increases with an increase in daylight exposure, whereas malondialdehyde (MDA) content increases with an increase in daylight exposure [16]. Interestingly, these changes in photoperiod also induce alterations in crustacean body colors [22].…”