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The effect of two commercial feeds of differing protein content, 35% or 40% (HI-35 and EXP), on Pacific White Shrimp Litopenaeus vannamei, performance, and system water quality were investigated. J...

Biofloc-based systems use little water and may recycle nutrients through the water column microbial community; fish-free diets may be more ecologically and financially sustainable than traditional feeds. A 12-week study examined the effects of biofloc (solids) management and a fish-free diet on shrimp quality. Four treatments were created; two used a conventional feed (including fishmeal and fish oil), one with solids management (CF-S) and one without (CF), and two treatments used a fish-free feed, one with solids management (FF-S) and one without (FF); each treatment was randomly assigned to four 3600-L tanks. The FF and FF-S shrimp had significantly lower lipid concentration and more manganese. Potassium was higher in CF-S shrimp versus CF; phosphorus was lowest in FF-S shrimp, and FF shrimp had the highest zinc levels. The CF shrimp had significantly higher omega-3s than FF shrimp, although omega-3 levels in FF shrimp were higher than the feed. This, coupled with higher omega-3 levels in the biofloc than the feed, may indicate that shrimp obtained some fatty acids from the biofloc material. The CF-S and FF-S shrimp had significantly greater sweet aromatic aroma, and the FF and FF-S shrimp had significantly higher first bite moisture release, mastication moisture release, and mastication fibrous/stringy texture. These results should be considered to optimize product quality of biofloc-raised shrimp fed fish-free diets.

The present study was conducted to evaluate the efficacy of organic acid blends as dietary antibiotic replacer in marine fish olive flounder, Paralichthys olivaceus. Fish averaging 3.5 ± 0.05 g (mean ± SD) were fed one of the four experimental diets: (1) without antibiotic or organic acid (Control/CON); (2) with antibiotic—50 mg oxytetracycline per kg body weight per day (OTC); (3) with organic acid blend A—4 g/kg diet (OAA); and (4) with organic acid blend B—4 g/kg diet (OAB), for 10 weeks. At the end of the experiment, total intestinal bacterial counts in fish‐fed OAA, OAB and OTC were significantly lower than that of fish‐fed CON diet (p

The present experiment was conducted to evaluate the effects of trace mineral (Cu, Zn, Mn and Fe) premixes from inorganic and chelated (chelated to 2-hydroxy-4-methylthiobutanoic acid or hydroxy analog of methionine; Mintrex™, Novus International Inc., St. Charles, MO, USA) sources, in rockfish, (Sebastes schlegeli). fed diets containing mineral inhibitor phytic acid. Seven isonitrogenous (46% crude protein/CP) and isocaloric (16.63 KJ available energy per g diet) semi-purified diets comprising of a Basal control and diets supplemented either with the inorganic (I) or chelated premix (M) at three different levels of 0.75 (I0.75/M0.75), 1.5 (I1.5/M1.5) and 3 (I3/M3) g kg−1 diets were formulated. Twenty-four fish averaging individual wet body weight of 9 ± 0.2 g (Mean ± SD) were fed one of the experimental diets in quadratic group for 16 weeks. Average weight gain (WG) of fish fed M3 was significantly higher than that of fish fed Basal control and I1.5 diets (P

The present experiment was conducted to evaluate the efficacy of trace minerals (Cu, Zn and Mn) premixes from inorganic and chelated (chelated to 2-hydroxy-4-methylthiobutanoic acid or hydroxy analog of methionine; Mintrex™) sources, in juvenile Pacific white shrimp, ( Litopenaeus vannamei ) fed plant protein based practical diets. Eight experimental diets comprising a trace minerals (Cu, Zn and Mn) deficient Basal control, and diets supplemented with the trace mineral premixes at four different levels of 2.5 (M 2.5 ), 5 (M 5 ), 7.5 (M 7.5 ) and 8.5 g/kg (M 8.5 ) from chelated source and at three different levels of 5 (I 5 ), 8.5 (I 8.5 ) and 20 g/kg (I 20 ) from inorganic source were formulated. Eleven numbers of juvenile shrimp averaging 0.6 ± 0.01 g (mean ± SD) were fed one of the eight experimental diets in triplicate groups for 8 weeks. At the end of the feeding trial, shrimp fed M 2.5 and I 8.5 diets exhibited the similar final weight (FW) and weight gain (WG) ( P 5 compared to I 8.5 diet ( P Zn super oxide dismutase (Cu Zn SOD) from the serum and hepatopancreas tissue was recorded to be peaked for the group of shrimp fed M 5 diet. Moreover, plasma protein and glucose levels were recorded to be similar between the groups of shrimp fed M 2.5 and I 20 diets ( P L. vannamei ) fed plant protein based diets. Statement of relevance The significance of trace mineral bioavailability has become more important as the composition of majority of commercial fish feed has been changing and there is an increased use of dietary plant protein. As a result, the bioavailability of trace minerals is being adversely affected by the presence of antagonistic factor such as phytic acid in plant protein. Even though, our knowledge in fish nutrition has advanced significantly, the information on trace minerals requirement is still limited and fragmentary. Inorganic form (sulfate/nitrate) of trace mineral has traditionally been used in aquafeed formulation. However, the limited bioavailability of inorganic source of trace mineral due to its higher affinity to antinutrients has hastened the search for alternative form of inorganic trace minerals. Overall performance observed in the present experiments vouched the potential benefit of using chelated trace mineral, Cu, Zn & Mn premix in marine shrimp, Pacific white shrimp to promote the optimum growth, trace minerals saturation in shrimp body and tissue as well as to ensure the optimum enzyme activity and health of cultured shrimp. The present experiment opens a new avenue to compare the efficacy of inorganic and chelated source of trace minerals in other commercially important marine and fresh water fish species. Whereas, the sustainability issue has put a new dimension in aquafeed formulation with a wide array of new ingredients and additives, on the other hand, the importance of basic nutrient such as trace minerals is still in sideline. Substantial investment and integrated scientific efforts are warranted to bridge the knowledge gap and further improve our understandings on the significance of dietary trace mineral in fish nutrition and health at the least cost to environment.

Superintensive shrimp culture in zero-exchange, biofloc-dominated production systems is more biosecure and sustainable than traditional shrimp farming practices. However, successful application of this technology depends upon optimizing dietary formulations, controlling Vibrio outbreaks, and managing accumulative changes in water quality and composition. A 49-d study investigated the effect of two commercial feeds of differing protein content and an indoor limited-exchange, biofloc-dominated culture environment on Litopenaeus vannamei performance and tissue composition, water quality and ionic composition, and Vibrio dynamics. Juveniles (5.3 g) were stocked at 457/m3 into four 40 m3 shallow raceways containing biofloc-dominated water and fed one of two commercial feeds with differing protein content, 35 or 40%. Shrimp performance, Vibrio populations, and changes in shrimp and culture water composition were monitored. There were no significant differences (P > 0.05) in shrimp performance (survival, weight, growth, specific growth rate, total biomass, yield, feed conversion ratio, and protein efficiency ratio) or proximate composition between feed types. The 40% protein feed resulted in higher culture water nitrate and phosphate concentrations, alkalinity consumption and bicarbonate use, and higher phytoplankton density. The presence of Vibrio, specifically Vibrio parahaemolyticus, reduced shrimp survival. This survival decrease corresponded with increased culture water Vibrio concentrations. Culture water K+ and Mg2+ increased significantly (P

Gilthead sea bream juveniles were fed different doses (0, 50, 100, 200, 300ppm) of NEXT ENHANCE®150 (NE) for 9 weeks. Feed gain ratio (FGR) was improved by a 10% with all the doses, but feed intake decreased in a dose dependent manner. The optimum inclusion level to achieve maximum growth was set at 100ppm. The hepatosomatic index did not vary and only at the highest dose, viscerosomatic and splenosomatic indexes were significantly decreased. No significant changes were found in haematological parameters, plasma biochemistry, total antioxidant capacity and respiratory burst. In a second trial, NE was given at 100ppm alone (D1) or in combination with the prebiotic PREVIDA® (0.5%) (PRE) (D2) for 17 weeks. There were no differences in the growth rates, and FGR was equally improved for D1 and D2. No significant changes in haematology and plasma antioxidant capacity were detected. The histological examination of the liver and the intestine showed no outstanding differences in the liver, but the number of mucosal foldings appeared to be higher in D1 and D2 vs CTRL diet and the density of enterocytes and goblet cells also appeared higher, particularly in the anterior intestine. A 87-gene PCR-array was constructed based on our transcriptomic database (www.nutrigroup-iats.org/seabreamdb) and applied to samples of anterior (AI) and posterior (PI) intestine. It included 54 new gene sequences and other sequences as markers of cell differentiation and proliferation, intestinal architecture and permeability, enterocyte mass and epithelial damage, interleukins and cytokines, pattern recognition receptors (PRR), and mitochondrial function and biogenesis. More than half of the studied genes had significantly different expression between AI and PI segments. The functional significance of this differential tissue expression is discussed. The experimental diets induced significant changes in the expression of 26 genes. The intensity of these changes and the number of genes that were significantly regulated were higher at PI than at AI. At PI, both diets invoked a clear down-regulation of genes involved in cell differentiation and proliferation, some involved in cell to cell communication, cytokines and several PRR. By contrast, up-regulation was mostly found for genes related to enterocyte mass, cell epithelial damage and mitochondrial activity at AI. The changes were of the same order for D1 and D2, except for fatty acid-binding proteins 2 and 6 and the PRR fucolectin, which were higher in D2 and D1 fed fish, respectively. Thus, NE alone or in combination with PRE seems to induce an anti-inflammatory and anti-proliferative transcriptomic profile with probable improvement in the absorptive capacity of the intestine that would explain the improved FGR. © 2015 Elsevier Ltd., This work has been carried out with financial support from the Commission of the European Communities, specific RTD programme of Framework Programme 7, (FP7/2007-2013) under grant projects ARRAINA (KBBE-2011-288925) and AQUAEXCEL (262336) under TNA project 0019/02/04/14 to ANDROMEDA. It does not necessarily reflect the EU views and in no way anticipates the Commission's future policy in this area. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Additional funding has been received by Spanish MINECO project no. AGL2013-48560 and Generalitat Valenciana (PROMETEOII/2014/085 and ISIC/2012/003).

White spot syndrome virus (WSSV) is a virulent pathogen of cultured shrimp and was first detected in farms in South Carolina (USA) in 1997 and subsequently in wild shrimp in 1999. We screened groups of 1808 wild Atlantic white shrimp Litopenaeus setiferus and 300 blue crabs Callinectes sapidus collected from South Carolina, Georgia, and Florida for the presence of WSSV using the Shrimple ® immunoassay-strip test, with all positives and random subsets of negatives tested by TaqMan real-time PCR and in infectivity bioassays. Of 87 shrimp and 11 crabs that tested positive using the Shrimple ® test, only a single C. sapidus was confirmed to be infected with WSSV by PCR and the infectivity bioassay. The data indicate that the prevalence of WSSV in these species is low in these southeastern US regions, but that C. sapidus may serve as a biological reservoir.

In 2011, aquaculture accounted for almost 64 million MT of fish, crustaceans and mollusks (FAO, 2012). Fish meal has historically been the protein source of choice in aquatic feeds, but global supplies have reached a plateau making it less available and more expensive. As a consequence, the use of cheaper proteins made from processed plant proteins, byproducts from agriculture, fisheries or the slaughtering of terrestrial production animals was popularized within the aquaculture feed industry. Although these alternative ingredients may contain a crude protein (CP) content comparable to fish meal, they may be less digestible and deficient in one or more of the ten essential amino acids (EAAs). This has required the adoption of more modern formulation approaches which take into account nutrient availability, especially in regard to EAAs. EAA requirements have been established for a number of species of fish and shrimp. Methionine (Met) followed by lysine (Lys) are the first limiting amino acids in plant and rendered animal byproducts. Formulating for EAAs by simply increasing the dietary inclusion levels of the feedstuffs that contain intact sources of the targeted EAAs can lead to overformulated feeds with excessive levels of CP and other nutrients. A more rational approach is to supplement the diet with crystalline amino acids (CAAs). A first step to the application of a nutrient-based formulation approach is knowledge of the digestible EAA content of the ingredients available for use in the formula. It is highly desirable to formulate on a CP, EAA and energy digestibility basis in line with current formulation practices of most modern feed companies. Further expansion of current EAA digestibility values across ingredients and farmed aquatic species will further enable nutrient based formulation. By formulating on an EAA basis across farmed aquatic species, nutritionists have realized least cost formulation opportunities with the use of CAAs which are now available throughout the world at accessible prices. The CAAs mostly used by the animal feed industry, in order of usage, are the following: dl -methionine or Met analogs, l -lysine, l -threonine, l -tryptophan, l -isoleucine and l -valine. Met and Lys are the most currently used due to their wide availability and importance as most limiting EAAs in plant protein ingredients, such as soy and corn based meals. There is a relatively wide variation in the dietary Met and Lys requirement values for farmed fish and shrimp. This is due to differences in species requirements, culture systems, developmental stage and composition of experimental diets. The dietary Met requirements for fish and shrimp range from 0.5 to 1.5% and from 0.7 to 0.9% of the diet, respectively (NRC, 2011). The dietary Lys requirements range from 1.2% to 3.3% of the diet for cultured fish and from 1.6 to 2.1% of the diet for cultured shrimp. Appropriate dietary Met and Lys levels improve the use of other EAAs because they have the ability to reduce the oxidation rate of other amino acids. The present review discusses bioavailability, requirements and sources of EAAs and practical considerations for their application in aquaculture feeds. The appropriate supplementation of crystalline amino acids in feeds for fish and shrimp represents an opportunity to reduce formulation costs in the face of the volatile commodity market of protein ingredients and the short supply of fish meal. Competitiveness in the aquatic animal feed industry today depends upon application of modern and environmentally-sound formulation techniques based on nutrient value and supplementation with crystalline EAA to meet animal nutrient requirements.

Six isonitrogenous (320 g kg−1) and isolipidic (60 g kg−1) diets were formulated with graded levels (0, 5, 10 and 15 g kg−1) of dicalcium phosphate (DCP) and fungal phytase (750 and 1500 FTU kg−1 diet). Tra catfish (Pangasianodon hypophthalmus), 9.6 g, were fed the diets for 12 weeks. Each experimental diet was fed to eight replicates of fish to apparent satiation. At the end of the trial, fish fed the diets containing 15 g kg−1 DCP, 750 and 1500 FTU kg−1 phytase had higher growth performances, protein efficiency ratio and phosphorus retention than those fed the control diet, 5 g kg−1 DCP and 10 g kg−1 DCP diets (P

Copper is an essential trace element for shrimp and plays important roles in growth, immune function, enzyme function, tissue integrity and as a component of the respiratory pigment hemocyanin. The presence of antagonists in feeds may result in reduced bioavailability and deficiency of copper which could compromise the growth and health of shrimp. A study was conducted to evaluate the response of Pacific white shrimp Litopenaeus vannamei to inorganic or chelated sources of dietary copper. A semi-purified basal diet composed principally of casein, gelatin, soy protein isolate, squid muscle meal and wheat starch was formulated to be deficient in copper (8 ppm). The diet contained 35% crude protein, and 8% lipid and supplied all other nutritional requirements of the shrimp. Two sets of diets were formulated from the basal diet, one supplemented with copper from copper sulfate (55, 80, 116, 168, 243 and 363 ppm copper respectively) and the other with copper from a chelated source of copper (chelated to hydroxy analog of methionine; 26, 39, 52, 65 and 83 ppm copper respectively). All experimental diets contained 1.2% phytic acid. Groups of juvenile shrimp (N = 8; 0.4 g initial weight) were fed the different diets for a period of 6 wk. At the end of 6 wk the average final weight of shrimp ranged from 8.75 g to 10.11 g and the growth rate ranged from 1.47 to 1.71 g/wk. In general shrimp required 3–4 times more dietary copper from copper sulfate than copper from a chelated copper source to promote comparable growth. Growth rates for treatment groups fed 168 and 243 ppm copper sulfate were significantly higher than the base group. Similarly, growth rates in shrimp fed 52 and 83 ppm copper from the chelated source were also significantly higher than that observed for the basal group. Whole body and hepatopancreas copper concentrations varied in relation to dietary copper supplementation. Tissue copper concentrations were significantly lower in shrimp fed the basal diets. Results from the study suggest that chelated copper is a safe, effective and highly available source of copper for the Pacific white shrimp.

The microbial community in minimal-exchange, superintensive culture systems should be managed to cycle nutrients and enhance production. This paper explores the effects of biofloc concentration reduction and a fish-free diet on several microbial community characteristics. In 16, 3.5-m diameter, 71-cm deep outdoor tanks, shrimp were stocked at 460/m3. Eight of the tanks received a fish-free, plant-based feed and eight received a conventional feed containing fishmeal and fish oil. Within each diet type, biofloc concentration was reduced in four of the tanks and was not reduced in the other four tanks. Photosynthetically active radiation (PAR) extinction coefficients, photosynthetic oxygen production, chlorophyll-a (chl-a) concentrations, pheophytin-a (pheo-a) concentrations, and the sum of odd and branched chain fatty acid concentrations as a bacterial abundance indicator (BAI) were measured. Biofloc reduction significantly (P≤ 0.003) decreased PAR extinction coefficients, chl-a concentration, pheo-a concentration, and BAI concentration, while significantly increasing photosynthetic oxygen production. Diet did not significantly affect (P > 0.05) any of these measured parameters. The observed changes in microbial community characteristics corresponded with, and may help to explain, significantly improved shrimp feed conversion ratios, growth rate, final weight, and biomass yield in the tanks with biofloc reduction.

The present study was conducted to determine the safe and toxic levels of dietary copper in juvenile olive flounder, Paralichthys olivaceus, fed Mintrex® copper, a chelated dietary copper source. Fish averaging 3.8 ± 0.13 g (mean ± SD) were fed 1 of 10 diets (n = 3) containing 7 (Cu0), 10.4 (CuM5), 15.8 (CuM10), 24.9 (CuM20), 43.4 (CuM40), 82.1 (CuM80), 158 (CuM160), 308 (CuM320), 658 (CuM640), and 1267 (CuM1280) mg Cu/kg diet. At the end of 12 wk of feeding trial, weight gain (WG), specific growth rate, and protein efficiency ratio of fish fed CuM5 and CuM10 diets were significantly higher than those fed CuM80, CuM160, CuM320, CuM640, and CuM1280 diets (P < 0.05). Survival of fish fed Cu0, CuM5, CuM10, CuM20, and CuM40 diets was significantly higher than those of fish fed CuM320, CuM640, and CuM1280 diets. Whole-body lipid content of fish decreased while whole-body ash increased with dietary copper levels. Whole-body and tissue copper concentrations increased with dietary copper levels. Although ANOVA test suggested that the toxic level of dietary Cu in juvenile olive flounder, P. olivaceus, could be 320 mg/kg diet, broken-line analysis of WG indicated a level of 286 mg/kg diet when Mintrex®Cu is used as the dietary copper source.

This work evaluated the performance of Litopenaeus vannamei to low fish meal diets supplemented with 2-hydroxy-4-(methylthio)butanoic acid (HMTBa). A basal diet with 150.0 g kg−1 of anchovy fish meal was designed. Two positive control diets were formulated to reduce fish meal at 50% and 100% with 1.0 and 2.0 g kg−1 of MERA™ MetCa (calcium salt with 84% HMTBa activity), respectively. Two nearly equivalent diets acted as negative controls, without HMTBa supplementation. A total of 50 clear-water tanks of 500 L were stocked with 2.22 ± 0.19 g shrimp under 70 animals m−2. Shrimp survival (92.3 ± 5.1% and 81.4 ± 8.0%), yield (808 ± 12 and 946 ± 17 g m−2) and FCR (2.17 ± 0.19 and 3.12 ± 0.37) showed no differences among diets after 72 or 96 days, respectively. A significantly higher shrimp body weight and weekly growth were observed for those fed with the basal diet or diets supplemented with HMTBa compared with non-supplemented ones. This study has shown that L. vannamei growth, body weight, survival, yield and FCR were supported by HMTBa supplementation when 150.0 g kg−1 of fish meal was replaced by soybean meal and other ingredients, at 50% and 100%.

This chapter contains sections titled: Introduction EST Collection as an Approach to Gene Discovery in Shrimp Medium- to High-Throughput Studies of Differential Expression and Gene Discovery RNAi-Based Applications in Shrimp Aquaculture: From Reverse Genetics to Control of Diseases Markers, Genetic Maps, and Large Insert Genomic Libraries in Shrimp Analytical Challenges in Genomics and Genetics of Shrimp Concluding Remarks Acknowledgments References

Microalgae hold a key role in the diet of the world's highest-valued seafood species, Pacific white shrimp Litopenaeus vannamei, but ingestion, digestion, and feeding mechanisms employed for consuming suspended microbes are not well studied. The goal of this work was to determine whether juvenile L. vannamei could consume and digest several microbes of varying sizes and structures in suspended monocultures. Diatoms Thalassiosira weissflogii and Amphiprora sp., eustigmatophyte Nannochloropsis salina, and cyanobacterium Synechococcus bacillarus were chosen based upon their common occurrence in intensive shrimp aquaculture systems. Juvenile 2 g L. vannamei, previously starved for 24 h, were individually stocked in aerated flasks containing axenic monocultures of T. weissflogii, Amphiprora sp., N. salina or S. bacillarus for 15, 30, 60, and 90 min. After designated immersion times, shrimp were dissected for collection of stomach and intestine content samples. Fluorometry was used to measure chlorophyll a (μg/g) within the stomach and intestine contents at each time increment. Counts of intact cells (cells/g) within the stomach and intestine contents were completed for shrimp that had been immersed for 60 min. Shrimp demonstrated a sweeping behavior of the third maxillipeds during submersion in some algal cultures, which led to examination through scanning electron microscope photography. Counts of intact cells and chlorophyll a levels in the stomach and intestine indicated that juvenile shrimp actively ingested and digested T. weissflogii and Amphiprora sp. from suspended monocultures. Diatom consumption and digestion were evident across all immersion times, with increasing levels of chlorophyll a in stomach samples up to but not significantly beyond 60 min, indicating that the experimental time period represented a continuous feeding period and spanned the gut passage time. Shrimp were able to ingest S. bacillarus and N. salina to a very limited degree, but there was no evidence of digestion of these cells. Examination under the scanning electron microscope revealed that the third maxillipeds have net-like setae which could potentially select for microorganism > 10 μm in size. Since this cell size reflected the difference between those cells consumed or not consumed in this study, we hypothesize that these appendages may be used by juvenile L. vannamei to filter food particles. These observations provide valuable insight regarding this shrimp's ability to capture and digest microalgae both within its natural environment and in aquaculture systems.

The extent to which data-intensive studies of the transcriptome can provide insight into biological responses is not well defined, especially in the case of species (such as shrimp) where much physiological and biochemical knowledge is missing. In this study we took a transcriptomic approach to gain insight into the response to viral infection of two strains of the Pacific whiteleg shrimp (Litopenaeus vannamei) that differ in their resistance to Taura Syndrome Virus (TSV). Changes in gene expression in the hepatopancreas following infection with TSV and Yellow Head Virus (YHV) were assessed using a cDNA microarray containing 2469 putative unigenes. The null hypothesis tested was that significant differences between the transcriptomic responses to viral infection of resistant and sensitive strains would not be detected. This hypothesis was broadly rejected, with the most surprising observation being that the baseline (control, unchallenged) sensitive and resistant strains expressed distinguishable transcriptomic signatures. The resistant line was pre-disposed to lower expression of genes encoding viral (and host) proteins. Many of the genes differentiating resistant and sensitive lines are involved in protein metabolism, cellular trafficking, immune defense and stress response, although it was not possible to clearly identify candidate genes responsible for TSV resistance. In contrast to TSV challenge, YSV either failed to perturb the host transcriptome or created a "confused" response that was difficult to interpret.

Minimal-exchange, intensive culture systems require little, if any, water exchange and have high animal stocking densities. Intensive nutrient inputs lead to an abundant community of microorganisms. These microbes are partially contained within suspended “biofloc” particles and contribute to water quality maintenance and provision of supplemental nutrition to the culture species. Optimal function of minimal-exchange, intensive systems is likely dependent on the structure of the microbial communities within them. This document offers a short review of microbial groups important for intensive marine aquaculture and descriptions of three methods for quantifying their abundance. The document also describes an experiment during which these methods were used to monitor the effects of partial biofloc removal on microbe abundance. The first method uses light microscopy, with the option of epifluorescence, along with a ranking system to enumerate the abundance of microbial taxa. The second method exclusively uses epifluorescence to illuminate chlorophyll and cyanobacteria pigments. Images are taken of each fluorescing group of pigments and processed using image analysis software to quantify the respective abundance of the two pigment types. Using the third method, changes in bacterial abundance were determined by gas chromatographic measurement of bacteria-specific fatty acids in solvent extracted water column lipids. Using these techniques, it was determined that removing solids from the culture water significantly (P ≤ 0.01) reduced the abundance of nematodes, rotifers, cyanobacteria, and bacteria. Understanding microbial composition and the effects that management protocols have on that composition may help system managers make better informed decisions.

Litopenaeus vannamei is one of the most important species of farmed shrimp. The females have an ‘open’ thelycum. Mating is accomplished by attaching the male spermatophore onto the surface of the thelycum 4–6 h before spawning. During this period, sperm may have to undergo morphological changes associated with a capacitation process that has been described for other shrimp species. The objective of this research was to extend research on sperm capacitation in L. vannamei by ultrastructural and biochemical means. The sperm of L. vannamei were divided into those freshly prepared from the spermatophore (S-sperm), extracted from the male gonopores, and those extracted from the female thelycum (T-sperm). Under transmission electron microscopy, ultrastructural differences were detected between the S- and the T-sperm in the nuclear material, the filamentous meshwork and the cytoplasmic particles. Under scanning electron microscopy, the difference was observed in the cap and spike regions. Immunofluorescence using confocal microscopy to detect tyrosine phosphorylated proteins revealed different distribution patterns between S- and T-sperm. The location of phosphorylation activity changed from the spike in S-sperm, to the filamentous meshwork in the T-sperm. These morphological and biochemical changes confirm that capacitation of L. vannamei sperm takes place following mating.

Many questions remain unanswered regarding RNAi-based mechanisms and dsRNA-induced antiviral immune responses in penaeid shrimp. In this study, we report the characterization in the white leg shrimp Litopenaeus vannamei of RNAi pathway associated proteins Lv-Ago 1 and Lv-Ago 2, two members of the Argonaute family of proteins, as well as Lv-sid 1, the first shrimp homologue of Sid-1, a membrane channel-forming protein implicated in the cellular import of dsRNA. To decipher their functional implication in RNAi-related phenomena, we monitored their relative expression following stimulation by specific and non-specific RNA duplexes of diverse length. The findings show that the length of small RNA duplexes plays a critical role in the activation of both RNAi-related and innate antiviral responses. They also suggest that these two mechanisms of antiviral response may activate the same pathway, requiring Lv-Sid 1 and Lv-Ago 2 induction. (C) 2010 Elsevier Ltd. All rights reserved.

In minimal-exchange, superintensive culture systems, the flocculated (biofloc) particles that accumulate may provide benefits for cultured shrimp; however, excessive particle accumulation can hinder shrimp performance. Also, the shrimp aquaculture industry is reliant on marine fish-based feeds. Using these products can lead to exploitation of marine resources, the introduction of contaminants to cultured shrimp, and unstable production costs. This study examined the use of simple, side-stream settling chambers as a means of controlling the abundance of particles in the water column and demonstrated the effects on water quality and shrimp production. The study also compared water quality and shrimp production parameters between a commercial, fish-based diet and a diet formulated almost entirely from vegetarian components, with expelled soybean meal as its principle protein source. The fish-based diet and the plant-based diet each contained 35.7% and 36.4% crude protein and 11.0% and 10.8% total lipid, respectively. The experiment was conducted in 3.35 m diameter, outdoor tanks, shrimp were stocked at 460 m − 3 and grown for 12 weeks. By the end of the experiment, settling chambers had removed 59% of suspended solids, decreased turbidity by 57%, reduced nitrate–nitrogen concentration by 60%, reduced phosphate concentration by 61%, and caused a 33% increase in alkalinity, all highly significant effects. Settling chambers also contributed to significantly improved shrimp feed conversion ratio, biomass, growth rate, and final weight ( P = 0.002, 0.006, − 3 ) was 41% greater in treatments with solids management than those without. Shrimp survival was not statistically different with or without settling chambers. Water quality parameters were not statistically different between the two diet types, except phosphate concentration which, by the end of the experiment, was 34% lower in the tanks receiving the plant-based diet. Shrimp production parameters were not statistically different between the two diets. The study showed that controlling the concentration of particles in superintensive shrimp culture systems can significantly improve water quality and shrimp production. Also, an environmentally friendly and potentially economical plant-based diet can produce results comparable to a fish-based feed in superintensive shrimp culture systems.

Gross and net photosynthesis, and water column respiration of a super-intensive Litopenaeus vannamei raceway culture with zero water exchange were measured over 21 weeks using the light and dark bottle method. Spearman correlation analysis was used to explore the relationship of these parameters with other water quality parameters (O2, temperature, pH, alkalinity, TAN, NO2, NO3, dissolved orthophosphate, turbidity, TSS and VSS) and of shrimp performance based on growth rate and feed conversion rate. Net photosynthesis generally had negative values, indicating that the system was predominantly heterotrophic. Gross photosynthesis was significantly related only with VSS, and water column respiration was related only with turbidity. Shrimp growth rate increased with higher temperature and dropped with higher pH. Nitrite had a strong inverse relationship with shrimp growth rate (R2 = 0.8044, p

A mechanistic model was developed to describe the thermal behavior of an indoor raceway system with an inflated double polyethylene cover. The model describes the heat balances of the two covers, the inside air, the water in the raceway and the soil beneath the raceway. On-site measurements were made with an experimental system at the Waddell Mariculture Center in South Carolina. The collected data were used to calibrate the model. Comparison of the predictions with observations showed that the average absolute errors of air temperature and water temperature were 1.4 and 0.5 °C, respectively and was 8% for the relative humidity. The accuracies are regarded as sufficient for the model to be useful for more general application. Model simulations were used to investigate the effects of the greenhouse on the air and water temperatures, to examine the heat fluxes and to calculate the heat consumption and costs at four different climatic locations. The results suggest that under the mild weather conditions in January near Charleston, SC where the daily mean temperature is 7.6 °C and solar radiation is 121 W m−2, the inside air temperature increases by 5.6 °C and water temperature increases by 9.7 °C on average for the system with the 0.85 m deep raceway covering 70% of the greenhouse floor. An examination of the heat fluxes suggests that thermal radiation is a major mechanism of heat loss for the greenhouse covers and the water surface. Convection from the water surface is also a significant mechanism for latent and sensible heat loss from the raceway. Reducing these heat flows will help conserve and utilize energy. The yearly heating requirements to keep the water temperature at 28 °C for the experimental system were estimated to be 870, 520, 274 and 221 kWh per square meter of raceway for Syracuse, NY, Roanoke, VA, Charleston, SC and Baton Rouge, LA, respectively. The model was deemed to be a useful tool for exploring the performance of greenhouse raceway systems under different scenarios, such as different cover materials, sizes and climates.

This work aimed at determining the dissolved oxygen consumption rate of Litopenaeus vannamei juveniles maintained in a microbial biofloc raceway system at high density with no aeration. Three 4 L bottles were filled for each treatment, sealed hermetically, and placed in an enclosed greenhouse raceway system. Four shrimp (13.2±1.42 g) were assigned to two sets of the bottles, which underwent the following treatments: light conditions with no shrimp; dark conditions with no shrimp; light conditions with shrimp; and dark conditions with shrimp. Dissolved oxygen content was measured every 10 min for 30 min. A quadratic behavior was observed in dissolved oxygen concentration over time. Significant differences for oxigen consumption were observed only at 10 and 20 min between shrimp maintained in the dark and those under light conditions. At 10 min, a higher value was observed in shrimp maintained under light, and at 20 min, in the dark. Significant differences between 10 and 20 min and between 10 and 30 min were observed when oxygen consumption was analyzed over time in the presence of light. Under dark conditions there were significant differences only between 20 and 30 min. Lethal oxygen concentration (0.65 mg L-1) would be reached in less than one hour either under light or dark conditions with no aeration.

Reproductive performance of unilateral eyestalk ablated and unablated wild and pond reared Penaeus semisulcatus was compared in a series of experiments in Eilat, Israel. Tagging techniques were used to study the maturation and spawning of individual females. The average numbers of spawns and eggs per ablated females were more than double those produced by unablated females, although fewer eggs per spawn were produced by ablated females. There were no significant differences in spawn quality, as measured by the percent fertility, hatch, and metamorphosis to zoea 1, between ablated and nonablated females. Egg production of ablated females was consistent for 70 to 80 days after which a decline was observed. The average rate of egg production of nonablated shrimp was more erratic with an apparent decline only after 100 to 110 days. No significant differences were found in spawn size or spawn quality between the first three spawns of ablated and nonablated females. A significant reduction in spawn size was apparent over the molt cycle although the percent fertility remained constant. Spermatophore transfer rates of 84 to 92% were achieved with female to male rations of 1.8:1 to 2.5:l. A reduction in fecundity was observed for successive generations of pond-reared brood stock. Eyestalk ablation was used to stimulate spawning of P. semisulcatus in captivity with no significant reduction in brood stock survival or in spawn quality.

Apoptosis has long been observed in viral target organs of white-spot syndrome virus (WSSV)-infected shrimp and whether the phenomenon helps the shrimp to survive the infection or is a factor leading to mortality is still controversial. If the shrimp mortality is a result of triggered apoptosis, then inactivation of caspase-3, a key protein in the induction of apoptosis, should improve shrimp survival upon challenge with WSSV. To test this prediction, we identified and characterized a caspase-3 homologue (cap-3) from the Pacific white shrimp Penaeus (Litopenaeus) vannamei and used this information to silence cap-3 expression by RNA interference prior to WSSV challenge. After confirming the efficacy of cap-3 silencing, its effects on mortality at high and low doses of WSSV were evaluated. In a high-dose WSSV challenge, cap-3 silencing had no significant effect on WSSV-induced mortality, except for a delay in mean time to death. However, at a low-dose WSSV challenge, cap-3 silencing correlated with a lower level of cumulative mortality, relative to silencing of a control gene, suggesting that apoptosis may exacerbate rather than decrease mortality in WSSV-challenged shrimp.

Infectious disease constitutes a major obstacle to the sustainability of shrimp aquaculture worldwide and a significant threat to natural populations of shrimp and other crustacea. The study of the shrimp immune system, including the response to viral infection, has been hampered by a relative lack of molecular genetic information and of tools suitable for high-throughput assessment of gene expression. In this report, the generation of a cDNA microarray encompassing 2,469 putative unigenes expressed in gills, circulating hemocytes, and hepatopancreas of Litopenaeus vannamei is described. The unigenes printed on the microarray were derived from the analyses of 7,021 expressed sequence tags obtained from standard cDNA libraries as well as from libraries generated by suppression subtractive hybridization, after challenging shrimp with a variety of immune stimuli. The general utility of the cDNA microarray was demonstrated by interrogating the array with labeled RNA from four different shrimp tissues (gills, hemocytes, hepatopancreas, and muscle) and by analyzing the transcriptomic response of shrimp to a lethal challenge with white spot syndrome virus. Our results indicate that white spot syndrome virus infection upregulates (in the hepatopancreas) genes encoding known and potential antimicrobial effectors, while some genes involved in protection from oxidative stress were found to be downregulated by the virus.

Reduction or elimination of fish meal and fish oil from aquaculture diets can help to reduce the potential for contamination and dependence of the industry on pelagic fisheries while improving economic competitiveness. However, fish oil provides important omega-3 (n-3) fatty acids (FAs) essential to shrimp health and beneficial to humans. This study evaluated an organic, plant-based diet formulated to replace fish meal and fish oil with plant proteins and docosahexaenoic acid (DHA) produced by algal fermentation. Shrimp cultured in replicate outdoor ponds at 25/m2 were fed either a diet composed of organically produced plant ingredients or a conventional commercial fish-meal-based feed. No significant differences were found in production parameters between the conventional fish-meal-based diet and the plant-based diet (production: 4594 and 4592 kg/ha; harvest size: 18.7 and 19.2 g; survival: 93 and 88%; and feed conversion ratio: 1.4 and 1.3, respectively). At harvest, shrimp were analyzed for 147 chemical contaminants and 71 FAs. Contaminant levels were negligible for shrimp raised on both diets. The fish meal and fish oil diet provided significantly higher quantities of eicosapentaenoic acid and DHA than the plant-based diet, and the shrimp fed the conventional diet reflected this with higher levels of these beneficial FAs in edible tissues. Differences between feeds and shrimp tissues suggest that essential n-3 FAs may accumulate in shrimp tissues over time or that natural pond productivity may play a role in providing supplemental nutrition. Shrimp raised on the two diets and wild-caught shrimp are clearly distinguishable by their FA profiles. Compared to alternative protein sources like beef, pork, or chicken, differences in lipid profiles of shrimp raised on either diet may be insignificant because both offer increased human health benefits.

A 15-week growth trial was conducted with juvenile, Pacific white shrimp Litopenaeus vannamei to study the efficacy of using algal meals as a source of highly unsaturated fatty acids in practical diets that are designed to contain no marine protein or oil sources. Based on previous study, a practical diet was designed containing co-extruded soybean poultry by-product meal with egg supplement and soybean meal as the primary protein sources for formulations containing 350 g kg−1 crude protein and 100 g kg−1 lipid. To further refine the diets, the fish oil in two of the diets was completely substituted with plant oils and oil originating from microbial fermentation products rich in docosahexanoic acid (DHA) and arachidonic acid (ArA). A commercial shrimp feed was also included in the trial for comparison. The mean values for shrimp final weight (17.8 g), yield (537.7 g m−2 or 703.2 g m−3), survival (98.5%) and feed conversion ratio (1.4 : 1) showed no statistically significant differences between diets. The results suggest that co-extruded soybean poultry by-product meal and oil from heterotrophic microalgal fermentation sources can be potential candidates for fish meal and marine oil replacement in shrimp diets.

Interest in culturing the Pacific white shrimp Litopenaeus vannamei in low-salinity and brackish-well waters has led to questions about the ability of this species to osmo- and ionoregulate in environments containing low concentrations of ions and in environments with ionic ratios that differ from those found in sea water. After seven days, hemolymph osmolality and potassium, sodium and calcium values were all significantly affected by salinity (as artificial sea salt) with values decreasing with decreasing salinity. These decreases were small, however, relative to decreases in salinity, indicating iono- and osmoregulation with adjustment for gradients. The hemolymph osmolality and sodium and calcium concentrations in shrimp exposed to either 2 g/L artificial sea salt or 2 g/L mixed-ion solution (a mixture of sodium, potassium, calcium, and magnesium chlorides that approximate the concentrations and ratios of these cations found in 2 g/L dilute seawater) did not differ significantly. However, hemolymph potassium levels were significantly lower in shrimp held in the mixed-ion environment. Potassium influx rates were similar in shrimp held in either artificial sea salt or mixed ions. The results of this study indicate that salinity affects hemolymph-cation concentrations and osmolality. Further, differential potassium-influx rates do not appear to be the basis for low hemolymph potassium levels observed in shrimp held in mixed-ion environments.

Zero water exchange, super-intensive culture of shrimp in enclosed raceway type systems can be considered environmentally friendly in that containment of water within the system prevents potential spread of disease between the wild populations and cultured animals and avoids nutrient rich waste from polluting coastal waters. However, as a relatively new strategy for shrimp production, there is much still to be learned about the potential biological and economic benefits of producing shrimp in suspended microbial floc based systems. Understanding shrimp feeding behavior and quantification of shrimp feed consumption provides valuable information for culturists to improve feed management, one of the keys to economic viability. The objective of this study was to evaluate the nutritional contribution of varying levels of microalgae/bacterial floc on survival, growth, food consumption, and FCR of Litopenaeus vannamei juveniles fed diets with different protein levels in replicated experimental microcosm tanks. The 20 day experiment evaluated 9 treatments, three water types fed three different protein diets. Water was recirculated within a sump and consisted of either clear, UV filtered water, water containing microbial floc from an adjacent zero exchange super-intensive raceway production unit, or a 50:50 mix of clear water and raceway water. Diet treatments were either no food, 25% or 35% protein content. Treatments were randomly assigned to 50 L, mesh covered plastic bins receiving each water type. Each treatment consisted of five replicates, each containing 44 shrimp, with a mean stocking weight of 1.82±0.71 g for a final density of 300 per m 2 . Shrimp in each treatment (except the no feed treatment) were fed 3 times daily via a specially designed feed tray. Food consumption and FCR were calculated based on weight gain, survival, total consumed feed, feed loss through leaching, and initial feed moisture content. Results were analyzed by two-way analysis of variance (ANOVA) and differences between the means analyzed by Tukey's test (α=0.05). Survival in the fed treatments was greater than 98% in all treatments (P>0.05). Survival in the non-fed treatments was significantly higher in the raceway water treatments than in the clear water treatment (P

White spot syndrome virus (WSSV) is a prevalent and virulent pathogen affecting both wild and cultured penaeid shrimp worldwide. Molecular diagnostic tools have made detection of the virus increasingly accurate. However, these techniques are often not readily available for rapid diagnosis in the field or in shrimp production facilities. Shrimple®, an immunochromatographic detection assay for WSSV, was designed specifically for use by shrimp producers. In this study, WSSV-infected shrimp were tested with both real-time PCR and Shrimple®, in order to determine the range of sensitivity in which the diagnostic test kit is capable of detecting viral infection and the efficiency of the test kit when compared to the real-time PCR. Litopenaeus vannamei were injected with a WSSV inoculum and sampled from 1 to 32 h post injection (p.i.), prior to developing gross anatomical signs of disease. By analyzing the corresponding samples from each specimen, the Shrimple® test results were correlated with estimated viral copy numbers from quantitative PCR. Real-time PCR detected infections in 100% of the inoculated shrimp, while the Shrimple® test kits detected infection in only 34.7% of the specimens. The findings of this study indicate that the Shrimple® test kits fail to detect WSSV infection prior to 12 h post infection and demonstrate a significant reduction in detection efficiency during early onset of infection—failing to detect any viral infection from 1 to 8 h p.i. compared to 100% with real-time PCR. False negative results were observed for specimens containing 4-1061 viral copies/ng genomic DNA. Faint positives were observed for specimens containing 36-1784 viral copies/ng genomic DNA. Although considerably less sensitive than real-time PCR, the Shrimple® test kits provide a useful tool for the detection of WSSV infections prior to development of gross signs of acute disease.

Strict environmental regulations and the high cost of land limit the growth of coastal aquaculture in developed countries. Finding ways to successfully culture marine species in inland systems may prove to be more economically viable. An important step in developing inland culture of marine species is to identify minimal environmental ion concentrations and ratios required for economical growth. Recent research has examined the potential for Pacific white shrimp, Litopenaeus vannamei, to be cultured in low-salinity environments (Laramore et al. 2001; McGraw et al. 2002; Atwood et al. 2003; Saoud et al. 2003). However, little research (Atwood et al. 2003; McNevin et al. 2004) has been conducted to assess shrimp survival in environments that are not dilute seawater. This experiment is based on previous work performed in our laboratory that has shown that L. vannamei exhibits no differences in growth or survival when grown in 2 and 20 g/L sea salt and that a 2 g/L mixed-salt environment (the term mixed salts is used here to refer to the chlorides of sodium, calcium, potassium, and magnesium) does not support growth and survival as well as an equal concentration of sea salt (Sowers et al. 2005). Our objective in this experiment was to determine if L. vannamei grow as well in 1 g/L dilute seawater plus 1 g/ L mixed salts as it would in 2 g/L dilute seawater. Equivalent growth would allow for the partial substitution of less expensive mixed salts for sea salt, reducing the need for sea salt in inland culture systems. Materials and Methods

Double-stranded RNA (dsRNA) is a common by-product of viral infections and a potent inducer of innate antiviral immune responses in vertebrates. In the marine shrimp Litopenaeus vannamei , innate antiviral immunity is also induced by dsRNA in a sequence-independent manner. In this study, the hypothesis that dsRNA can evoke not only innate antiviral immunity but also a sequence-specific antiviral response in shrimp was tested. It was found that viral sequence-specific dsRNA affords potent antiviral immunity in vivo, implying the involvement of RNA interference (RNAi)-like mechanisms in the antiviral response of the shrimp. Consistent with the activation of RNAi by virus-specific dsRNA, endogenous shrimp genes could be silenced in a systemic fashion by the administration of cognate long dsRNA. While innate antiviral immunity, sequence-dependent antiviral protection, and gene silencing could all be induced by injection of long dsRNA molecules, injection of short interfering RNAs failed to induce similar responses, suggesting a size requirement for extracellular dsRNA to engage antiviral mechanisms and gene silencing. We propose a model of antiviral immunity in shrimp by which viral dsRNA engages not only innate immune pathways but also an RNAi-like mechanism to induce potent antiviral responses in vivo.

The uptake, depuration and toxicity of environmental nitrite was characterized in Litopenaeus vannamei exposed in water containing low concentrations of artificial sea salt or mixed salts. In 2 g/L artificial sea salts, nitrite was concentrated in the hemolymph in a dose-dependent and rapid manner (steady-state in about 2 d). When exposed to nitrite in 2 g/L artificial sea salts for 4 d and then moved to a similar environment without added nitrite, complete depuration occurred within a day. Increasing salinity up to 10 g/L decreased uptake of environmental nitrite. Nitrite uptake in environments containing 2 g/L mixed salts (combination of sodium, potassium, calcium and magnesium chlorides) was similar to or lower than rates in 2 g/L artificial sea salt. Toxicity was inversely related to total dissolved salt and chloride concentrations and was highest in 2 g/L artificial sea salt (96-h medial lethal concentration = 8.4 mg/L nitrite-N). Animals that molted during the experiments did not appear to be more susceptible to nitrite than animals that did not molt. The shallow slope of the curve describing the relationship between toxicity and salinity suggests that management of nitrite toxicity in low-salinity shrimp ponds by addition of more salts may not be practical.

In 1997, white spot syndrome virus (WSSV) was discovered in shrimp culture facilities in South Carolina, USA. This disease was known to cause devastating mortalities in cultured popula- tions in Southeast Asia and prompted concern for the health of wild populations in the USA. Our study surveyed wild shrimp populations for the presence of WSSV by utilizing molecular diagnostics and bioassay techniques. A total of 1150 individuals (586 Litopenaeus setiferus, 477 Farfantepenaeus aztecus and 87 F. dourarum) were examined for the presence of WSSV DNA by PCR. A total of 32 individuals tested positive and were used in a bioassay to examine the transmission of disease to healthy individuals of the culture species L. vannamei. DNA sequencing of PCR products from a pos- itive individual confirmed that the positive individuals carried WSSV DNA. Significant mortalities were seen in test shrimp injected with tissue extracts from heavily infected wild shrimp. These data confirm the existence of WSSV in wild shrimp stocks along the Atlantic Coast and that the virus can cause mortalities in cultured stocks.

Intensive shrimp ponds are commonly aerated by placing paddlewheel aerators parallel to the pond dikes. This placement creates a relatively rapid water current along the pond banks, while leaving a center region with much slower flow. Implications of this flow mode were studied in three 0.25-ha ponds. Measurements of water flow, sludge depth, dissolved oxygen and pH were taken throughout a pond, and contour graphs were created and verified by several transect measurements on different dates in the same pond and in two other ponds. The distribution of the measured parameters suggests these ponds have two primary regions: a relatively well-mixed and aerated outer region, and a virtually stagnant, vertically stratified inner region. During the early morning, the inner region had significantly lower DO than the outer region in all ponds and on all dates. In contrast, during the afternoon, inner surface water DO ranged from nearly twice to nearly half that of outer surface water. This wide range in the inner region was facilitated by the minimal effect of mechanical aeration in this region and the consequentially larger affect of variable photosynthesis and oxygen demand. The separation between inner and outer regions was very distinct, and characterized by a drop in water speed from about 10 cm/s to less than 2 cm/s within 5 m. Sludge depth and organic matter accumulation were higher in the inner region, facilitating the lowest DO and pH measurements in the bottom water of this region. Shrimp abundance, as indicated by trap catches, was significantly lower in the center region, suggesting conditions may have been less favorable for shrimp growth and health over as much as 30% of the pond area. The results obtained in this work raise the need for renewed thought, development and assessment of alternative aeration strategies in intensive shrimp ponds.

A study was conducted to evaluate the response of Pacific white shrimp Litopenaeus vannamei to inorganic or chelated sources of dietary zinc. Two sets of diets, one supplemented with zinc from zinc sulfate (55, 80, 116, 168, 243 and 363 ppm zinc) and the other with zinc from a chelated source (methionine hydroxy analog chelate; 39, 52, 65, 78 and 104 ppm zinc) were fed to replicate groups of juvenile shrimp (N = 8; 0.4 g initial weight) for 6 wk. All experimental diets contained 1.38% phytic acid reflecting levels in typical commercial feeds. Final weight, growth rate and biomass of shrimp fed zinc sulfate supplemented diets (243 and 363 ppm total zinc) were significantly higher (p < 0:05) than that in shrimp fed the base diet. In contrast, performance of shrimp fed the chelated source of zinc was significantly higher than shrimp in the control group at much lower levels of supplementation (65 and 78 ppm total zinc). Results indicate that shrimp required 3-4 times more dietary zinc from zinc sulfate than zinc from a chelated source to promote comparable growth when fed diets containing phytic acid. The chelate tested proved to be a safe, effective and available source of zinc for the Pacific white shrimp.

Immunostimulants are food additives used by the aquaculture industry to enhance the immune response of fish, and although β-glucans are now commonly used for this purpose in aquaculture, little is known about their effects on the immune response of Pangasianodon hypophthalmus. Thus, a variety of immune parameters (e.g. phagocytosis, respiratory burst, lysozyme, complement, peroxidase, total protein, total anti-protease, total IgM, natural antibody titres, and specific IgM titres) was examined in this species after feeding fish with a basal control diet or diets supplemented with 0.05, 0.1, or 0.2 g/kg fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan, as a positive control diet, for a period of four weeks. The effect of the glucans on disease resistance was then evaluated by experimentally infecting the fish with Edwardsiella ictaluri by immersion and mortalities monitored for 14 days. Samples were collected from fish for analysis at 0, 1, 3, 7, 14, 21 and 28 days post-feeding (dpf), and also at 14 days post infection (dpi). The lowest dose of fungal-derived β-glucan (0.05%) appeared insufficient to effectively stimulate the immune response of the fish, while those fed with the two highest levels of fungal-derived β-glucan had enhanced immune responses compared to the control group. Significantly elevated levels of respiratory burst activity on all days examined (P < 0.05) and lysozyme activity on 7 dpf were found in the group fed 0.2% fungal-derived β-glucan, while plasma anti-protease activity was significantly enhanced (P < 0.05) by 21 dpf, natural antibody titres by 3 dpf and complement activity by 7 dpf and also at 14 dpi in the group fed 0.1% fungal-derived β-glucan. No statistical differences was seen in the level of mortalities between the dietary groups, although the group fed with the control diet had the highest level of mortalities and the groups fed with commercial yeast-derived β-glucan and 0.2% fungal-derived β-glucan the lowest.

Growth and production of Pacific white shrimp (Litopenaeus vannamei) was examined along with water quality, and general indicators of microbial activity in replicate intensive tank cultures with no sediment, sand sediment, and sand sediment together with additional vertical surfaces (sand/mat). All treatments received similar feed and fertilizer input. Initial linear shrimp growth rates was relatively high (1.65 g/week) in all treatments. A reduction in growth rates was seen in the no-sediment and sand treatments, while linear growth continued longer in the sand/mat treatment. Shrimp weight, survival and production was significantly greater in the sand/mat treatment than in the sand and no-sediment treatments. While the latter two treatments yielded similar production, the no-sediment treatment required weekly additions of soda ash during the last month of the 104-day season to maintain a minimum pH of 7.0. Significantly higher pH, in conjunction with lower phytoplankton biomass and ammonia in the sand/mat treatment than in the sand treatment suggests greater carbon fixation by the attached algal community of the sand/mat treatment. This is further supported by similar carbon mineralization rates in all treatments as roughly indicated by water respiration rates in conjunction with greater sludge accumulation in the sand/mat treatment. Phyto and bacterioplankton levels were significantly lower in the sand/mat treatment than in the other treatments. Ammonia, nitrate and sludge accumulation were similar in the no-sediment and sand tanks. The sand/mat treatment had significantly greater nitrite than the other treatments. Water column nitrification rates were similar in the sand and no-sediment treatments and significantly greater in the sand/mat treatment, suggesting that nutrient cycling rates may be greater in this treatment. From a production standpoint, the primary difference in the no-sediment and sand treatments was the need for proactive management of pH in the no-sediment tanks. The quantity of vertical surface area addition tested in the sand/mat treatment of this study yielded higher shrimp production in conjunction with significant differences in water quality and indicators of general activity, suggesting that this relatively high level of vertical surface addition may significantly affect aquaculture production systems.

Effluent from aquaculture ponds may add to receiving waters high levels of biochemical oxygen demand (BOD), inorganic and organic particulate matter, live algae, dissolved organic matter, ammonia, nitrite, nitrate, phosphate, and other potential contaminants. We evaluated a method that used the eastern oyster Crassostrea virginica and a macroalga, Gracilaria tikvahiae, for biofiltering the effluent from a pond used for intensive culture of Pacific white shrimp Litopenaeus vannamei.2 Effluent flow rates of 2.0, 1.1, and 0.2% of pond volume/d were tested. Shrimp yield from the 0.5-ha pond after 129 d was 10,312 kg/ha; shrimp survival rate was 96.5%. Oyster biofiltration accounted for most of the decrease of turbidity, chlorophyll a, total suspended solids (TSS), and settleable solids. Following macroalgal biofiltration, decreases in ammonia, total nitrogen, and total phosphorus concentrations were observed. At a daily exchange rate of 7.5%, diversion of 1.1% of the pond volume to the treatment syst...

Plankton community establishment and shrimp production in a prototype biosecure pond were compared to three control ponds. The biosecure pond was enclosed and intake water was disinfected, while control ponds were neither enclosed nor disinfected. All ponds were managed with no water exchange and stocked with 100 postlarvae/m2, Litopenaeus vannamei. Residual oxidant concentrations in the biosecure pond dropped rapidly after cessation of chlorinated water addition. This was followed by a sharp increase in water column bacterial abundance, after which the pond was fertilized and inoculated with cultured Chaetocerous gracilis. After crash of the initial C. gracilis bloom in the biosecure pond, this species was not observed again. Following initial large fluctuations in biosecure pond bacterial abundance, phytoplankton biomass, oxygen consumption and nitrification rates, these parameters appeared to stabilize at levels similar to the control ponds. Early season compositional differences in phytoplankton, zooplankton, and bacterial communities were observed. No differences were seen in late-season phytoplankton and bacteria; however, zooplankton biomass tended to be lower in the biosecure pond than in the control ponds throughout the season. Shrimp production in all ponds was greater than 9,000 kg/ha. Production in the single biosecure pond was not a significant outlier compared to production in the triplicate control ponds.

Simple electrometric methods were tested to estimate microbial activity in hypereutrophic aquaculture ponds using equipment common at aquaculture facilities for biochemical oxygen demand (BOD) measurements. Activity measurements tested included net photosynthesis based on changes in dissolved oxygen (DO) concentrations in samples incubated under light and dark conditions; general microbial activity as indicated by oxygen consumption rates in the dark; nutrient limitations as indicated by changes in DO consumption rates with nutrient additions; and nitrification based on the difference in DO consumption rates between samples incubated with and without a nitrification inhibitor. Method evaluations in intensive shrimp culture ponds suggest that simple electrometric methods are a good index of water column microbial activity under a range of conditions.

Pond culture of marine shrimp currently accounts for about 30% of world supply and production continues to expand. The future success of shrimp farming will depend upon increasing supplies of healthy, high quality seed for stocking ponds. In many areas, fry are still collected from the wild for stocking into ponds. To stabilize seed supplies and expand to new areas, hatchery production technologies have improved slowly over the past 20 years. Challenges associated with disease control and reducing reliance on natural feeds are being met through research efforts in the private and public sectors. Improved hygiene and biosecurity, development of probiotics and immunostimulants and improvement of artificial feeds promise better postlarval fitness while reducing cost and improving reliability of production. However, much of this production continues to rely on nauplii derived from wild gravid spawners collected at sea. Although techniques for captive maturation and spawning have been well defined, serious gaps remain in the basic understanding of the hormonal control of reproduction, the process of vitellogenesis in penaeid shrimp and the mechanical and physiological processes involved in fertilization. Presently, in areas with readily available indigenous stocks of species of choice, there is a generally accepted perception among hatchery managers and growers that performance of nauplii and postlarvae derived from wild matured spawners is superior to captive matured or pond reared animals. As we approach the 21st century, wild stocks are facing increasing pressure and shrimp farming continues to expand into new areas, away from traditional sources of wild seed. New viral disease epidemics continue to arise and spread quickly across entire regions, significantly impacting industry viability. Research and development efforts aimed at closing the life cycle of several commercially important species are underway. While significant limitations remain, encouraging results illustrating the potential for disease control, disease resistance and improved growth have been reported. The development of healthy, genetically improved shrimp stocks represents a tremendous economic opportunity while potentially improving the outlook for long term industry sustainability. The present paper is a review of recent developments in penaeid broodstock and seed production technologies focusing on current limitations while defining the significant potential offered by emerging developments.

The culture of Pacific white shrimp Penaeus vannamei (PVA) within the geographical range of Atlantic white shrimp P. setiferus (PSE) has prompted concern regarding potential ecological risks. The present study evaluates the potential for spontaneous hybridization between these closely related litopenaeid species. Prezygotic barriers to hybridization were evaluated utilizing quantitative analysis of behavioral interactions associated with mating, artificial insemination, and a novel in vitro fertilization technique. There was a significant decrease in the number of interspecific behavioral interactions (P < 0.005). In total, 15 ♀ PSE × ♂PSE and 11 ♀PVA × ♂PVA matings were achieved. No spontaneous matings were observed between species. In artificial insemination trials, 60% of the intraspecific inseminations were fertile with mean fertilization rates of 9.21 ± 3.83% for PSE and 11.6 ± 5.2% for PVA. No interspecific crosses were fertile. This study documents in vitro fertilization for the first time in two litopenaeid species. In vitro fertilization was achieved by upwelling a concentrated sperm suspension under a spawning female. Three levels of negative controls were used to eliminate the possibility of contamination. Fertilization was achieved in 13 of 14 intraspecific trials with mean fertilization rates of 2.48 ± 0.57% for PSE and 3.88 ± 1.34% for PVA. No interspecific crosses were fertile. Based on the low levels of behavioral interaction during interspecific crosses, the lack of natural interspecific matings, and absence of fertilization in interspecific crosses for both artificial inseminations and in vitro fertilizations, the potential for hybridization between P. setiferus and P. vannamei appears to be negligible.