Pacific Whiteleg Shrimp Research Articles

Heat penetration characteristics and quality of ready‐to‐eat shrimp in masala ( Litopenaeus vannamei ) in flexible retortable pouches

Shrimp in masala is a famous south Indian dish prepared using white leg shrimp (Litopenaeus vannamei) in the culinary style. The present investigation was aimed to optimize different F0 values of the shrimp in masala packed in flexible retortable pouches. The product was thermally processed at different lethality and heat penetration characteristics indicating similar heating and cooling lag factor. Fh value was 24.5 and 23 min for the product processed at Fo values of 8 and 9 min, respectively. Total processing time was 37.11 and 39.88 min, respectively, for Fo 8 and 9 min. Cook value of the processed product was 84.07 min for Fo 8 min and 92.41 min for Fo 9 min. Except cohesiveness, all other instrumental texture parameters showed significant differences (p < .05) between the two samples. Based on the organoleptic evaluation, product processed at Fo 8 min was rated better. Practical applications Shrimps are regarded as one of the delicacy food items across the globe and hence has great demand. Currently, Pacific white leg shrimp is the most widely cultured shrimp variety. Shrimp in masala, an ethnic dish is very popular among Asians and elsewhere. However, due to its limited shelf life and preparation time, its consumption is limited only during special occasions. The present study optimizes the thermal process conditions to develop ready-to-eat Shrimp masala, which can be kept at ambient temperature for prolonged duration which can be made available to consumers year-round. Apart from this, during the period of glut production, this highly efficient and economical technology can be used for preserving shrimps in RTE form.

Aquaculture in Brazil: past, present and future

Aquaculture in Brazil probably started in the 17th century, during the Dutch occupation of the northeastern region. Currently, this activity can be divided into five main sectors, defined by tradition and type of cultured organism: freshwater fish, marine shrimp, mollusks, freshwater prawns and frogs. Production in 2019 was estimated at 800,000 tonnes, representing a gross revenue of US$ 1 billion. Freshwater fish is predominantly produced, followed by marine shrimp. The main farmed species are Nile tilapia (Oreochromis niloticus), tambaqui (Colossoma macropomum) and the Pacific white leg shrimp (Litopenaeus vannamei). Other species have great local socio-economic importance. The bulk of production comes from small farms: more than 80 % have less than 2 ha. Brazil has more than 200 thousand freshwater fish farms, about 3000 marine shrimp farms, and about 100 aquaculture research institutions. A large domestic market is available for edible fish and shellfish, ornamentals, baitfish and hatchery-reared juveniles for biomitigation purposes. The challenge is to develop truly sustainable production systems to support a perennial industry. New technologies, including digital devices and simple disruptive innovations, can increase productivity and support the shift to a circular economy, bioeconomics and sustainability supported by science-based innovations and knowledge.

Dry matter, protein, and energy digestibility of diets for juvenile Pacific white leg shrimps (Litopenaeus vannamei) reared at different salinity levels

ABSTRACT: This study evaluated the effect of low, medium, and high-water salinity (5, 35, and 50 ppt) on the apparent dry matter, protein, and energy digestibility of two formulated and six commercial diets for juvenile whiteleg shrimp, Litopenaeus vannamei, in a 120-day trial. Digestibility was determined in vivo using chromic oxide as an inert diet marker. Hydrostability in pellets varied from 86.8% to 99.9%; dry matter digestibility varied from 49.1% to 64.1%; protein digestibility showed greater variations at all salinities (56.9%-85.8%); and energy digestibility ranged from 70.1 to 86.4%. Salinity had a significant effect on dry matter, protein, and energy digestibility. Using a principal component analysis (PCA) with a covariance matrix, our findings suggested that the E2 (fishmeal-based formulation) diet and 35 ppt salinity provided optimum hydrostability and digestibility to Pacific white leg shrimp juveniles.

Abundance of introduced Pacific whiteleg shrimp Penaeus vannamei (Boone, 1931) along the east coast of Thailand

Abundance of introduced Pacific whiteleg shrimp Penaeus vannamei (Boone, 1931) along the east coast of Thailand

Evidence of Marine Microplastics in Commercially Harvested Seafood.

Microplastic pollution is a global issue that has a detrimental impact on food safety. In marine environments, microplastics are a threat to marine organisms, as they are often the same size range as prey and are mistaken as food. Consumption of microplastics has led to the damage of digestive organs and a reduction in growth and reproductive output. In this study, microplastic pollution was assessed across three commercially available shrimp species that were obtained from the supermarkets of Singapore. A total of 93 individuals were studied from the Pacific white leg shrimp, Litopenaeus vannamei, the Argentine red shrimp Pleoticus muelleri and the Indian white shrimp Fenneropenaeus indicus. Microplastic fibers, fragments, film and spheres were identified from the digestive tract of these organisms. Microplastic abundance ranged from 13.4 to 7050 items. F. indicus exhibited the highest number of microplastics. Microplastic film was the most abundant in L. vannamei individuals (93–97%) and spheres were the most abundant in P. muelleri (70%) and F. indicus (61%) individuals. This study demonstrates that microplastic contamination is evident in commonly consumed shrimp and highlights the role of shrimp in the trophic transfer and accumulation of microplastics in seafood. The consumption of microplastic-containing seafood is a route of exposure to humans and has implications on human health and food security. Capsule: Microplastics were examined in three shrimp species from the supermarkets of Singapore. Microplastics ranged from 13.4 to 7050 items of shrimp.

Supplementation of combined mannan oligosaccharide and β-glucan immunostimulants improves immunological responses and enhances resistance of Pacific Whiteleg Shrimp, Penaeus vannamei, against Vibrio parahaemolyticus infection

A feeding trial was conducted to evaluate the combined effects of mannan oligosaccharide ( MOS) + β-glucan (BZT® PRE-GE) supplementation administered at different frequencies on the immune responses and resistance of Penaeus vannamei against Vibrio parahaemolyticus, the causative agent of Early Mortality Syndrome (EMS) disease. Four experimental treatments were run with shrimps fed with a control basal diet (TCo), fed daily with diet containing 0.2 % MOS+ β-glucan (Td), fed every 3 days with diet containing 0.2 % MOS+ β-glucan (Td3) and fed every 7 days (Td7) with diet containing 0.2 % MOS+ β-glucan. Following the 30-day feeding trial, shrimp immunological responses were quantified. Infection challenge test was also conducted to evaluate the influence of the treatments on the resistance of P. vannamei against V. parahaemolyticus infection. Results indicate that the immunostimulant application frequency did not affect shrimp survival and overall growth performance. Immunostimulant application every 3 days was found optimum to enhance the immunological responses including total hemocyte count, prophenol oxidase and serum antibacterial activities. Moreover, significant improvement in survival following the infection challenge with V. parahaemolyticus was observed in treatment fed with the immunostimulant every 3 days. Overall these findings suggest that 0.2 % MOS+ β-glucan supplementation applied every 3 days could enhance the immune responses and improve the resistance of P. vannamei against Vibrio parahaemolyticus infection. Administration of 0.2 % MOS+ β-glucan once every 3 days could be a practical immunoprophylactic strategy to manage and prevent outbreaks of mass mortalities caused by V. parahaemolyticus infection in P. vannamei farming.

Deciphering the molecular regulatory mechanism orchestrating ovary development of the Pacific whiteleg shrimp Litopenaeus vannamei through integrated transcriptomic analysis of reproduction-related organs

Ovary development of decapod crustaceans is controlled by a complex neuro-endocrine regulatory network. In crustacean aquaculture, eyestalk ablation (ESA) technique has been widely used to induce ovary development and maturation. However, this technique can cause significant hormonal imbalance leading to inferior egg quality and weak immunity of the animals. Understanding the molecular regulatory mechanism of ovary development will help to develop alternative measures to expedite ovarian maturation. In this study, we performed a comprehensive transcriptomic analysis of five important organs related to ovary development, including the eyestalk ganglion, brain, thoracic ganglion, hepatopancreas, and ovary, at different ovary developmental stages of the Pacific white shrimp Litopenaeus vannamei. A total of 698,118,770 clean reads were obtained from the Illumina HiSeq™ 4000 sequencing platform, resulting in an assembly of 48,722 unique transcripts (or unigenes) with an N50 of 2463 bp and a mean length of 1244 bp. 18,661 unigenes can be matched to homologous sequences in public databases. Pairwise comparisons revealed that a wide variety of genes were differentially expressed and several gene expression trends were significantly enriched in different organs during ovary development. Through weighted gene co-expression network analysis, six tissue- or stage-specific modules of co-expressed genes were identified. GO and KEGG analysis further disclosed that a rich set of genes, including those associated with the CHH family hormones, ecdysone signaling, juvenile hormone signaling, Insulin-PI3K-Akt signaling, EGFR signaling, and TGFβ signaling pathways, were preferentially expressed in specific tissues, implying their crucial roles in the regulation of ovary development process. Taken together, the study reports a comprehensive analysis of transcriptomic modulation in major neuro-endocrine organs related to shrimp ovary development. The data obtained sheds light on the potential coordination between the nervous system and its target organs (i.e. ovary and hepatopancreas), and contributes to a deeper understanding of the regulatory network orchestrating ovary development of shrimp.

Effects of Biofloc Application on Survival Rate, Growth Performance and Specific Growth Rate of Pacific Whiteleg Shrimp, Penaeus vannamei Culture in Closed Hatchery System.

Biofloc application has been introduced in aquaculture in order to reduce the nutrients level and sustain good water quality. Due to its importance, a study was conducted to identify the effect of biofloc application on shrimp growth performance, specific growth rate and survival rate in a closed hatchery system. Molasses as carbon sources were applied in ratio 10:1 for biofloc formulation and no addition of molasses in non-biofloc (clear water) treatment. One way ANOVA was applied to analyze the differences between biofloc treatments and clear water. The survival rate of the shrimp was ranged between 23.69 and 98.77% for biofloc treatment, whereas 98.15-99.23% for non-biofloc treatment. The lowest survival rate (23.69%) was due to vibriosis infection in one of the biofloc treatment tanks. Growth performance was identified expedite in biofloc especially in (dark green) colour biofloc as compared to non-biofloc. The Specific Growth Rate (SGR) for Body Weight (BW) was identified expedite around (3.25-4.06) g day-1 for biofloc treatment compared to non-biofloc around (2.74-3.93) g day-1. The SGR for (TL) also identified expedite around (2.12-2.45) cm day-1 for biofloc, compared to non-biofloc (clear water) around (1.71-2.13) cm day-1. It can be concluded that the biofloc application successfully improved the shrimp performance and at the same time become the additional natural diet to the shrimp respectively. However, further study needs to be conducted to improve the survival rate and prevent vibriosis infection by using the biofloc system in the future.

Characterization of Vibrio alginolyticus bacteriophage recovered from shrimp ponds in south west of Iran

Farming of the pacific white leg shrimp (Penaeus vannamei), consists the greatest percent of aquaculture production of crustaceans all over the world. Vibriosis caused by Vibrio species such as Vibrio alginolyticus, is a serious limiting agent for aquaculture. Phage therapy is an eco-friendly alternative to antibiotics as a prophylactic measure for the growth of pathogenic bacteria. The aim of this study was isolation and characterization of Vibriophages present in Litopenaeus vannamei breeding and culture facilities and estuarine resources in south west of Iran, Choebdeh shrimp farming site of Abadan city, Khuzestan Province, based on morphological structure, biological conditions and their potential applications in lysis of Vibrio bacteria. The bacterial and phage samples were analyzed using different physicochemical parameters, 16S rRNA gene sequencing and TEM. The results showed the V. alginolyticus isolates and identified the Podoviridae family of phages. These bacterial isolates were resistant to ampicillin and penicillin. The efficacy of the Podoviridae phage against V. alginolyticus bacterium indicated that this phage has a short period of 30 minutes latent phase, possessed a desirable stability and growth in keeping for 1 hour at 30-55oC, the salinity of 0.5-10 and pH of 5-8. Based on evaluation of phage therapy, mean absorbance values (OD600), in control and treatment groups, at 12 and 24 hours after phage inoculation, were significantly different (p <0.05). According to the results, phage therapy with single-phage suspensions did not prevent bacterial regrowth after treatment. However, delay in development of resistance is a desirable success.

Antibacterial spectrum of synthetic herbal-based polyphenols against Vibrio parahaemolyticus isolated from diseased Pacific whiteleg shrimp (Penaeus vannamei) in Thailand

Acute hepatopancreatic necrosis disease (AHPND) was first reported as a new shrimp disease in 2009, which caused serious disease in shrimp culture with global economic losses and high rates of mortality. Vibrio parahaemolyticus (VP) was recently identified as the leading causative agent of AHPND that contains Pir toxin bearing plasmid coding toxins (PirA and PirB). Classic antibiotic treatments have been used for the control of infections, however, the frequent use of antibiotics has led to the emergence of antibiotic-resistant bacterial strains of public health concern. The present study aimed to investigate the potential use of synthetic herbal-based polyphenols compounds as natural, eco-friendly antimicrobial agents for disease control. Polyphenols and their active ingredients were investigated against 96 VP isolates retrieved from Pacific whiteleg shrimp (Penaeus vannamei) in Thailand and compared with various commercial antibiotics using a broth microdilution method, time-kill assay, and scanning electron microscope (SEM). All VP isolates were identified using conventional bacteriology and molecular-based tools. Bacteriological examination revealed that all isolates harbored toxR gene with specific amplicons of 368 bp. Only 56 isolates were positive to AP3, a toxin-encoding gene of AHPND-VP with a fragment size of 336 bp. In terms of susceptibility, all isolates were entirely resistant to ampicillin and amoxicillin, whereas they showed different susceptibility patterns to the other tested antibiotics. Among the polyphenols, there was no apparent activity of syringic acid and rutin, while vanillic acid showed higher bactericidal activity against VP isolates at MICs and MBCs of 1024–2048 μg mL−1. Pyrogallol exhibited the strongest antibacterial activity even at very low concentrations with a MIC and MBC of 32–256 μg mL−1, and the majority of cells showed disruption and an indistinguishable cell wall structure by SEM analysis. The present study offers pyrogallol as a potential synthetic herbal-based antimicrobial agent for the adoption of inventory management practices and control of V. parahemolyticus causing AHPND in shrimp producing sectors.

Effect of a phytogenic feed additive on the growth performance and immunity of Pacific white leg shrimp, Litopenaeus vannamei, fed a low fishmeal diet

AbstractPlant‐derived products have been suggested to partially replace fishmeal in aquafeed; however, often at decreased growth performance, inflammatory responses, and increased susceptibility to diseases. This study assessed the effects of the commercial phytogenic feed additive Digestarom PEP MGE on the growth, nutritional performance, and immune response of L. vannamei. Juvenile shrimp (N = 540) were stocked in 36 tanks (V = 100 L) for 63 days and fed one of the four experimental diets: (i) standard formulation (control, 24% fishmeal), (ii) low fishmeal diet (5%), (iii) low fishmeal diet plus 0.2 g/kg Digestarom PEP MGE, and (iv) low fishmeal diet plus 0.4 g/kg Digestarom PEP MGE. The results obtained after 63 days of feed supplementation suggest that the blend of essential oils tested compensated for the negative performance and health consequences of the low fishmeal diet. Particularly, the survival, FCR, total hemocyte count, and respiratory burst of the shrimp fed a low fishmeal diet supplemented with this phytogenic improved up to the levels recorded for shrimp fed a high fishmeal diet. Overall, results suggest that Digestarom PEP MGE can be incorporated into shrimp low fishmeal diets to compensate for the negative performance and immunological effects of partially replacing fishmeal with plant‐based protein.

Increased robustness of postlarvae and juveniles from non-ablated Pacific whiteleg shrimp, Penaeus vannamei, broodstock post-challenged with pathogenic isolates of Vibrio parahaemolyticus (VpAHPND) and white spot disease (WSD)

The maturation and reproduction of Pacific whiteleg shrimp, Penaeus vannamei, through the practice of unilateral eyestalk ablation though common is an animal welfare concern. This study assessed the resilience of offspring from non-ablated P. vannamei when challenged with an isolate of Vibrio parahaemolyticus (Vp) causing acute hepatopancreatic necrosis disease (VpAHPND), and with white spot syndrome virus (WSSV). VpAHPND and WSSV challenges were conducted using PL and juveniles under controlled conditions, with both trials using four groups (i.e. shrimp from either ablated or non-ablated females and then either challenged with the pathogen or not challenged). For the VpAHPND challenge, ten replicate 20 L tanks (five replicates for each population) each containing 100 PL 17 (average weight 14 mg) in 15 ppt, 29.05 ± 0.13 °C water were challenged with 2 mL of 2.0 × 108 CFU mL−1 culture of V. parahaemolyticus. A further ten replicate tanks (five per population) served as the corresponding non-challenged controls. The shrimp mortalities were assessed every 3 h over the following 96 h. For the WSSV challenge, individual 1.4 g (average weight) shrimp (50 individuals per population) were housed in 1 L tanks and fed 0.1 g WSSV infected tissue (av. 2.02 × 109 WSSV). A further 50 shrimp per population served as non-challenged controls. The shrimp were maintained at 15 ppt, 26.3 ± 0.71 °C water and assessed every 3 h post-infection over the subsequent 168 h and mortalities at each time point noted. Postlarvae from non-ablated females had significantly (p = 2.4E-23) better survival (70.4%) than those from ablated females (38.8%) at 96 h post-challenge with VpAHPND. Both challenged populations had significantly (p ≤1.3E-36) lower survival than the control groups. The survival of the juveniles from non-ablated females (62%) at 168 h post-infection with WSSV was not significantly higher than that of the juveniles from ablated female (48%) although the difference was significantly different at 65 to 75 h. Both challenged populations also had significantly (p ≤1.0E-5) lower survival rates than the control groups. The study demonstrates that postlarvae and juveniles from non-ablated females are more resilient to typical pathogens (VpAHPND and WSSV) and may show higher survival rates during a disease outbreak.

Structure and co-occurrence patterns of bacterial communities associated with white faeces disease outbreaks in Pacific white-leg shrimp Penaeus vannamei aquaculture

Bacterial diseases cause production failures in shrimp aquacultures. To understand environmental conditions and bacterial community dynamics contributing to white faeces disease (WFD) events, we analysed water quality and compared bacterial communities in water as well as in intestines and faeces of healthy and diseased shrimps, respectively, via 16S rRNA gene sequencing and qPCR of transmembrane regulatory protein (toxR), thermolabile haemolysin (tlh), and thermostable direct haemolysin genes of pathogenic Vibrio parahaemolyticus as a proxy for virulence. WFD occurred when pH decreased to 7.71–7.84, and Alteromonas, Pseudoalteromonas and Vibrio dominated the aquatic bacterial communities. The disease severity further correlated with increased proportions of Alteromonas, Photobacterium, Pseudoalteromonas and Vibrio in shrimp faeces. These opportunistic pathogenic bacteria constituted up to 60% and 80% of the sequences in samples from the early and advances stages of the disease outbreak, respectively, and exhibited a high degree of co-occurrence. Furthermore, toxR and tlh were detected in water at the disease event only. Notably, bacterial community resilience in water occurred when pH was adjusted to 8. Then WFD ceased without a mortality event. In conclusion, pH was a reliable indicator of the WFD outbreak risk. Dissolved oxygen and compositions of water and intestinal bacteria may also serve as indicators for better prevention of WFD events.

CRISPR-Cas fluorescent cleavage assay coupled with recombinase polymerase amplification for sensitive and specific detection of Enterocytozoon hepatopenaei

Enterocytozoon hepatopenaei (EHP) is a parasite that infects pacific whiteleg shrimp, Penaeus vannamei, causing growth retardation and uneven size distributions that lead to severe losses in shrimp productivity. Routine monitoring is crucial to timely prevention and management of EHP, but field-deployable diagnostic kits for EHP are still scarce. Here, we proposed the use of recombinase polymerase amplification (RPA) and CRISPR-Cas12a fluorescence assay, henceforth RPA-Cas12a, for detection of EHP. Targeting ptp2 gene, RPA-Cas12a could detect as few as 50 copies of DNA and showed no reactivity with closely related microsporidia. The entire procedure could be performed at a temperature close to 37 °C within 1 h. Naked eye visualization was possible with UV/blue-light excitation or lateral flow detection. Thus, RPA-Cas12a is a rapid, sensitive and specific detection platform that requires no sophisticated equipment and shows promise for on-site surveillance of EHP.

Selection of reference genes for the study of relative gene expression during development of Litopenaeus vannamei larvae

Pacific whiteleg shrimp (Litopenaeus vannamei) production is one of the most economically important aquaculture industries around the world. Gene expression studies during larval development are a key tool to elucidate biological aspects during metamorphosis and the effects of pathological conditions; the adequate quantification of gene expression can provide molecular markers and basic knowledge to optimize culture conditions, including the development of strategies for the prevention and control of diseases. In this context, the selection and validation of reference genes is a critical process to avoid bias due to inaccurate measurements and the consequent misinterpretation of biological processes. In this study, nine candidate reference genes (Clathrin, Cyt-c, SubF0, EF1α, β-Actin, GAPDH, TBP, AK and PK) were selected to test their expression stability during larval development of L. vannamei using geNorm, NormFinder, BestKeeper and the integrated tool RefFinder algorithms. Based on our analysis the most stable gene was SubF0, followed by GAPDH and EF1α. Relative expression of developmental genes (Twist, Mef-2 and Ubx) was quantified using the three most stable reference genes (individually and combined), taking special attention to the expected expression and biological function of these genes. The expression of Mef-2 was the most sensitive to the reference gene. However, the combination of the three most stable reference genes provided consistent results according to the expected expression patterns of developmental genes.

Complete replacement of fishmeal by soybean and poultry meals in Pacific whiteleg shrimp feeds: Growth and tolerance to EMS/AHPND and WSSV challenge

Corresponding to projected global population growth, the world's food production systems must likewise enlarge substantially if current levels of dietary protein intake are to be maintained. The anticipated growth curve for global aquaculture, and especially for shrimp farming, which is forecast to double production by 2030, will inevitably result in shortfalls in currently favored dietary ingredients: fishmeal (FM) and fish oil (FO). Servicing the projected FM-FO shortfall with marine products would be a formidable task as economic, social, moral, safety and environmental issues have forced the feed sector to examine the use of alternative, non-marine, ingredients. Herein, various alternative protein and lipid sources were evaluated as substitutes for FM-FO in Pacific whiteleg shrimp diets. Growth trials were coupled to challenges with viral and bacterial pathogens to assess potential benefit or disadvantage of ingredient switching. No differences (P > .05) were observed between control and test diets regarding growth or survival, Average Daily Gain (g d−1) or Specific Growth Rate (% d−1) over a 56-day period. Moreover, response to post-feeding trial challenge with EMS/AHPND or WSSV also did not differ between diets (P > .05). However, there was a difference in size/age responsiveness to bacterial challenge, with younger animals succumbing to infection more rapidly (P ≤ .035). Similar responses were observed for shrimp exposed to WSSV over the first 5-days post-challenge (P ≤ .02) after which survival rates equalized. Overall, the results support the sustained belief that FM-FO constituents of Pacific whiteleg shrimp diets can be totally replaced by non-marine ingredients that are nutritionally equivalent. Improvement in responsiveness to substitute proteins and oils might be further gained with more judicious blending of ingredients and use of other additives. Such manipulations could also result in less expensive sustainable feeds.

Photobacterium damselae subsp. damselae associated with bacterial myonecrosis and hepatopancreatic necrosis in broodstock Pacific white leg shrimp, Litopenaeus vannamei (Boone, 1931)

This study presents the first report of myonecrosis and hepatopancreatic necrosis in broodstock of Litopenaeus vannamei. Of the 400 individuals examined, 34 displayed myonecrosis and hepatopancreatic necrosis, conditions previously reported to be caused by bacterial, fungal, parasite, and viral infections. Gross signs of infection include passive swimming, anorexic and the abdominal muscle become opaque with extensive whitish discoloration of distal abdominal segments and the posterior appendages. Macroscopic necropsy examination revealed atrophied hepatopancreas and empty stomach and mid-gut. The histopathological investigations revealed that reddened muscular lesions are composed of coagulative and liquefactive necrosis of striated muscle fibers, often with edema. The hepatopancreas showed necrotic lesions displaying disorganized lumen and dispersed tubular epithelial cells scattered on necrotic myoepithelial cells. Gill lamellae in infected shrimp showed disorganized, necrotic filaments infiltrated with inflammatory hemocyte. The RT-PCR analysis using OIE-recommended primer and additional sets of primers used in previous studies revealed the absence of IMNV as well as other emerging pathogens including MrNV, PvNV, WSSV, IHHNV, TSV, YHV, AHPND, and EHP. Basis on these negative results, microbiological tests were performed. A dominant yellow-colored bacterial colony was isolated on TCBS agar and identified as Photobacterium damselae subsp. damselae KPD. Injection of the isolate of P. damselae KPD proved to be pathogenic to L. vannamei. The study concludes that P. damselae KPD is the causative agent of myonecrosis and hepatopancreatic necrosis and represents a threat to the Indian shrimp hatcheries.

Effects of antimicrobial peptides on growth, feed utilization, serum biochemical indices and disease resistance of juvenile shrimp,Litopenaeus vannamei

This experiment was conducted to assess the effects of antimicrobial peptides at different levels (Diet 1 (0%), Diet 2 (0.1%), Diet 3 (0.2%), Diet 4 (0.4%), Diet 5 (0.6%) and Diet 6 (1%)), on growth, serum biochemical indices and antioxidant effect, feed utilization and disease resistance in Litopeneaus vannamei. There were four replicates in each group in the experiment (mean weight = 0.21 ± 0.00 g) and also fed with their respective diets for 8 weeks. Growth performance compared with the control group (0%) significantly increased at first and then decreased among treatment groups (p < .05) whereas the survival rate ranged from 78% to 96%. No significant differences were observed in terms of moisture, crude protein and ash content, but there was a significant increase in crude lipid (p < .05). In serum, acid phosphatase, alkaline phosphatase, polyphenol oxidase, triglyceride, glucose and total cholesterol changed as compared with 0%. Total antioxidant capacity, glutathione peroxidase, catalase, superoxide dismutase and malondialdehyde were also different from 0%. Disease resistance was increased in shrimp among treatment groups with 0.4% recording the lowest mortality percentage of 37% after the challenge test. The results from the present study suggested that supplementation of AMP at 0.4% in shrimp diet can improve growth performance, antioxidants activities and innate immune response of Pacific whiteleg shrimp.

Prospects for Genetic Improvement in Objective Measurements of Body Colour in Pacific Whiteleg Shrimp (Litopenaeus vannamei)

Body colour, together with growth and survival, are traits of commercial importance in Pacific whiteleg shrimp (Litopenaeus vannamei). However, heritability estimates for objective measurements of body colour are not available in Whiteleg shrimp species, including L. vannamei. Further, the effect of genotype by environment interactions (G × E) on this trait (i.e., the objective measures of body colour) and its genetic associations with growth are not known in this species. The present study presented the first attempt at understanding the genetic architecture of this complex character (body colour) that is of economic significance to the shrimp aquaculture sector world-wide. Specifically, we investigated the quantitative genetic basis of shrimp colour, while using the measurement tool (colorimeter) for a Whiteleg shrimp population reared in two contrasting environments. A total of 5464 shrimp had the objective measurements of body colour (lightness, yellowness, and redness) and growth trait records (weight, length and width). They were the offspring of 204 dams and 197 sires. The restricted maximum likelihood mixed model analysis showed that there were heritable additive genetic components for all of the measurements of shrimp colour, with the heritability (h2) ranging from 0.11–0.55. The h2 estimates for redness and yellowness traits differed between the two environments (h2 = 0.66–0.82 in Khanhhoa vs. 0.00–0.03 in Haiphong). However, the heritability for colour traits was moderate (0.11–0.55) when the two environments were combined. There is existence of (co)-genetic variances between the studied traits. The genetic correlations of body traits with redness or yellowness colour of the shrimp were moderate and positive (a*: 0.13–0.32 for redness and b*: 0.19–0.40 for yellowness). The effect of G × E interactions on shrimp colours could be important, as the genetic correlations for these traits between the two environments were low (−0.41 to 0.16). Our results showed that the genetic improvement for body colour can be achieved through direct selection and the increased redness colour is also expected to have favorable impacts on growth traits. Breeding programs to improve shrimp colour should account for the effects of environmental factors.

Fate of Hexabromocyclododecane (HBCD), A Common Flame Retardant, In Polystyrene-Degrading Mealworms: Elevated HBCD Levels in Egested Polymer but No Bioaccumulation

As awareness of the ubiquity and magnitude of plastic pollution has increased, so has interest in the long term fate of plastics. To date, however, the fate of potentially toxic plastic additives has received comparatively little attention. In this study, we investigated the fate of the flame retardant hexabromocyclododecane (HBCD) in polystyrene (PS)-degrading mealworms and in mealworm-fed shrimp. Most of the commercial HBCD consumed by the mealworms was egested in frass within 24 h (1-log removal) with nearly a 3-log removal after 48 h. In mealworms fed PS containing high HBCD levels, only 0.27 ± 0.10%, of the ingested HBCD remained in the mealworm body tissue. This value did not increase over the course of the experiment, indicating little or no bioaccumulation. Additionally, no evidence of higher trophic level bioaccumulation or toxicity was observed when L. vannamei (Pacific whiteleg shrimp) were fed mealworm biomass grown with PS containing HBCD. Differences in shrimp survival were attributable to the fraction of mealworm biomass incorporated into the diet, not HBCD. We conclude that the environmental effects of PS ingestion need further evaluation as the generation of smaller, more contaminated particles is possible, and may contribute to toxicity at nanoscale.