The Effects of Dietary Astaxanthin on Growth and Moulting Cycle of Postlarval Stages of the Prawn, Penaeus japonicus (Crustacea, Decapoda)

Effects of Astaxanthin on Growth Performance, Gut Structure, and Intestinal Microorganisms of Penaeus vannamei under Microcystin-LR Stress

Microcystin-LR (MC-LR) are biologically active cycloheptapeptide compounds that are released by cyanobacteria during water blooms and are extensively found in aquatic ecosystems. The Penaeus vannamei is a significant species in global aquaculture. However, the high level of eutrophication in aquaculture water frequently leads to outbreaks of cyanobacterial blooms, posing a significant threat to its sustainable cultivation. Astaxanthin (AX) is commonly utilized in aquaculture for its physiological benefits, including promoting growth and enhancing immune function in cultured organisms. This study aimed to examine the protective effect of astaxanthin on P. vannamei exposed to microcystin-induced stress. The experiment consisted of three groups: one group was fed formulated feed containing MC (100 μg/kg), another group was fed formulated feed containing MC (100 μg/kg) + AX (100 mg/kg), and the third group was fed basic feed (control group). After 15 days of feeding, the specific growth rate (SGR) was significantly higher in the MCAX group (2.21% day-1) compared to the MC group (0.77% day-1), and there was no significant difference between the MCAX group (2.21% day-1) and the control group (2.24% day-1). Similarly, the percent of weight gain (PWG) was also significantly higher in the MCAX group (14.61%) compared to the MC group (13.44%) and the control group (16.64%). Compared to the control group, the epithelial cells in the MC group suffered severe damage and detachment from the basement membrane. However, in the MCAX group, although there was still a gap between the intestinal epithelial cells and the basement membrane, the overall intestinal morphology was slightly less impaired than it was in the MC group. The analysis of the intestinal microbiota revealed a significant disparity in the community composition (chao 1 and ACE) between the MC and MCAX groups. When comparing the various bacterial genera, the MC group exhibited an increase in Vibrio abundance, whereas the MCAX group showed a decrease in both Shewanella and Vibrio abundance. The results indicate that AX has a positive impact on the growth performance and resistance of P. vannamei against MC by regulating the composition of the intestinal microbiota. AX can be utilized to mitigate the detrimental effects of MC in aquaculture practices. This function could be attributed to the role of AX in preserving the structural integrity of the intestinal mucosa and regulating the composition of the intestinal microbiota.

Growth Performance, Immune-Related and Antioxidant Genes Expression, and Gut Bacterial Abundance of Pacific White Leg Shrimp, Litopenaeus vannamei, Dietary Supplemented With Natural Astaxanthin

The current study examines the effect of dietary supplementation of ethanolic extract of Arthrospira platensis NIOF17/003, which is mainly natural astaxanthins (97.50%), on the growth performance, feed utilization, bacterial abundance, and immune-related and antioxidant gene expressions of the Pacific white leg shrimp, Litopenaeus vannamei. A total of 360 healthy L. vannamei postlarvae (0.19 ± 0.003 g) were divided into four groups (0, 2, 4, and 6 g natural astaxanthins/kg diet) each in three replicates, at an initial density of 30 PLs per tank (40 L capacity). The shrimp were fed the tested diets three times a day at a rate of 10% of their total body weight for 90 days. Diets supplemented with different astaxanthin levels significantly improved shrimp growth performance and feed conversion ratio compared to the control diet. No significant differences were observed in survival rates among all experimental groups. The immune-related genes (prophenoloxidase, lysozyme, beta-glucan binding protein, transglutaminase, and crustin) mRNA levels were significantly upregulated in groups fed with different concentrations of the natural astaxanthins in a dose-dependent manner. The prophenoloxidase gene is the highest immune-upregulated gene (14.71-fold change) in response to astaxanthin supplementation. The superoxide dismutase mRNA level was significantly increased with increasing dietary astaxanthin supplementation. In addition, increasing astaxanthin supplementation levels significantly reduced the count of heterotrophic bacteria and Vibrio spp. in the culture water and shrimp intestine. Overall, the current results concluded that diet supplementation with natural astaxanthin, extracted from Arthrospira platensis, enhanced the growth performance, immune response, and antioxidant status of L. vannamei.

A Newly Isolated Strain of Haematococcus pluvialis GXU-A23 Improves the Growth Performance, Antioxidant and Anti-Inflammatory Status, Metabolic Capacity and Mid-intestine Morphology of Juvenile Litopenaeus vannamei

Haematococcus pluvialis can be used as a green additive in aquafeeds due to it contains rich astaxanthin and polyunsaturated fatty acid. In the present study, a newly strain of H. pluvialis GXU-A23 with high concentration of astaxanthin was firstly isolated by a newly culture strategy in our laboratory. In addition, H. pluvialis GXU-A23 was applied in the Litopenaeus vannamei feed for determining whether it has positive effects on the growth performance, antioxidant and anti-inflammatory status, metabolic capacity and mid-intestine morphology of juvenile L. vannamei. Shrimp with 0.63 g approximately initial body weight were fed diets supplemented with/without 50 g/kg H. pluvialis GXU-A23. After 8 weeks feeding intervention, significantly higher growth performance of L. vannamei was obtained in the H. pluvialis GXU-A23 treatment group compared to the control group (p < 0.05). At the same time, L. vannamei fed with H. pluvialis GXU-A23 acquired significantly better antioxidant and anti-inflammatory status than the control group (p < 0.05). In addition, higher RNA expression level of hepatopancreas digestive enzyme, hepatopancreas lipid and glucose metabolic enzymes as well as better mid-intestine morphology were found in the H. pluvialis GXU-A23 treatment group than the control group (p < 0.05). These results indicated that 50 g/kg H. pluvialis GXU-A23 was suitable for the L. vannamei feed, which could improve the growth performance, antioxidant and anti-inflammatory status, metabolic capacity and mid-intestine morphology of juvenile L. vannamei.

Mechanisms of possible self-limitation in the invasive Asian shore crab Hemigrapsus sanguineus

Population sizes of invasive species are commonly characterized by boom-bust dynamics, and self-limitation via resource depletion is posited as one factor leading to these boom-bust changes in population size. Yet, while this phenomenon is well-documented in plants, few studies have demonstrated that self-limitation is possible for invasive animal species, especially those that are mobile. Here we examined the invasive Asian shore crab Hemigrapsus sanguineus, a species that reached very high abundances throughout invaded regions of North America, but has recently declined in many of these same regions. We examined the relationship between diet, energy storage, reproduction, and growth in crabs collected from the New Hampshire coast. We show that energy storage and reproduction both increase with diet quality, while growth declines with diet quality. These results suggest that self-limitation may be a contributing factor to the recent declines of H. sanguineus at sites where this invader was once much more abundant. Further, these results suggest a diet-associated tradeoff in energy allocation to different vital rates, with a focus on reproduction when high quality resources are consumed, and a focus instead on growth when poor quality resources are consumed.

Effects of Dietary Astaxanthin Supplementation on Energy Budget and Bioaccumulation in Procambarus clarkii (Girard, 1852) Crayfish under Microcystin-LR Stress

This research aimed to study the effects of astaxanthin on energy budget and bioaccumulation of microcystin-leucine-arginine (microcystin-LR) in the crayfish Procambarus clarkii (Girard, 1852). The crayfish (21.13 ± 4.6 g) were cultured under microcystin-LR stress (0.025 mg/L) and were fed with fodders containing astaxanthin (0, 3, 6, 9, and 12 mg/g) for 8 weeks in glass tanks (350 mm × 450 mm × 150 mm). Accumulations of microcystin-LR were measured in different organs of P. clarkii. The results suggested that astaxanthin can significantly improve the survival rate and specific growth rate (SGR) of P. clarkii (p < 0.05). The dietary astaxanthin supplement seems to block the bioaccumulation of microcystin-LR in the hepatopancreas and ovaries of P. clarkii to some extent (p < 0.05). Astaxanthin content of 9⁻12 mg/g in fodder can be a practical and economic choice.

Carotenoid as a sensitive indicator of sub lethal cadmium toxicity in Penaeus monodon post larvae

The objective of the present study is to evaluate a sensitive indicator of cadmium by measuring oxygen consumption and carotenoid concentration in post larvae of Penaeus monodon. The post larvae of P. monodon were exposed to 0.12 and 0.24 mg/L of cadmium in the laboratory for a period of 30 days. These concentrations represent 1/10th and 1/5th of 96 h LC50 value for the post larvae. Oxygen consumption and carotenoid concentration were measured at 24, 48, 96 h, 10 and 30 days of cadmium exposure. The results indicated an inhibition of routine oxygen consumption in post larvae at different intervals of exposure from 24 h to 30 days but the effect was statistically significant (P < 05) at 30 days of exposure at both sub lethal concentrations, where the inhibition was 38.5 % at 0.24 mg/L and 21.6 % at 0.12 mg/L. On the other hand, carotenoid concentrations increased gradually with increasing period of exposure as well as concentration, and this increase was statistically significant (P < 0.05) from 96 h onwards on exposure to 0.12 mg/L and from 48 h onwards on exposure to 0.24 mg/L of cadmium, with an overall highest increase of 135 %. As carotenoid content is an indicator of tissue oxygen, inhibition of routine oxygen consumption might have resulted in enhancing the levels of carotenoid. From the present data, it is evident that carotenoid concentration can be considered as a sensitive indicator of cadmium toxicity than routine oxygen consumption in the post larvae of P. monodon. The present investigation is also relevant for environmental monitoring of cadmium in coastal waters before it is used for aquaculture.

Effect of dietary astaxanthin against Aeromonas hydrophila infection in common carp, Cyprinus carpio

The effect of astaxanthin at 0, 25, 50, and 100 mg kg(-1) incorporated in basal feed on immune response and disease resistance in Cyprinus carpio against Aeromonas hydrophila was investigated. When fed with 25 mg kg(-1) diet, the cumulative mortality was 35% whereas it was 10% and 20% with 50 and 100 mg kg(-1) diets. With all enriched diets the growth rate increased significantly from week 1 to 4 when compared with control. However, the specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) did not vary significantly from that of the control except with 50 mg kg(-1) diet. When fed with 50 and 100 mg kg(-1) diets the red blood cells, white blood cells, hemoglobin, and hematocrit values significantly increased. However, the serum total protein, albumin, and globulin contents significantly increased only when fed with 50 and 100 mg kg(-1) diets. The phagocytic ratio also significantly raised with 50 and 100 mg kg(-1) diets on week 2 and 4 whereas the phagocytic index significantly increased with all groups only on fourth week. The respiratory burst activity significantly increased in 25 mg kg(-1) diet group on first week whereas in 50 and 100 mg kg(-1) diet groups the activity increased on weeks 2 and 4; a similar trend was observed in the anti-protease activity only on weeks 2 and 4. The serum lysozyme activity and bactericidal activity registered a significant increase with all enriched diets. This study suggests that supplementation of astaxanthin at 50 and 100 mg kg(-1) with the basal diet significantly promotes the growth restores hematology and modulates the immune system in C. carpio against A. hydrophila.

Carotenoid pigments and trophic behaviour of deep-sea shrimps (Crustacea, decapoda, alvinocarididae) from a hydrothermal area of the mid-atlantic ridge

Pigments and trophic behaviour of three species of Alvinocarididae from a Mid-Atlantic hydrothermal site were analysed. Carotenoid pigments are responsible for the more or less marked colouration of these animals. The carotenoid content of whole animals and different tissues were evaluated. Rimicaris exoculata exhibits an increased carotenoid level at the juvenile stage, while Chorocaris chacei and Alvinocaris markensis contain only few traces of pigment. Free and esterified astaxanthin, reported for most pelagic crustaceans, are present in these deep-sea shrimps. The origin of carotenoids of crustaceans living in the aphotic zone is discussed.

The effects of dietary astaxanthin on the carotenoid pattern of the prawn Penaeus japonicus during postlarval development

Penaeus japonicus postlarvae, reared under laboratory conditions, were fed an astaxanthin enriched diet to the investigate carotenoid metabolic capabilities during the postlarval development. Animals fed astaxanthin were found to absorb this carotenoid. The decrease of pigment concentration in the carotenoid starved group is related to the duration of the experimental feeding conditions; the carotenoid depletion depends upon the postlarval status at the starting point. As has been shown for adult prawns, the carotenoid pattern of postlarval stages, regardless of the diet, consists mainly of free and esterified astaxanthin; the relative amounts of these fractions undergo slight variations depending on the diet.