ABSTRACT Aquaculture combines techniques for breeding and harvesting aquatic organisms used in shrimp production. It is important as a source of income and for generating foreign exchange in the regions where it is practiced. However, the timely detection of diseases continues to be a great challenge for aquaculture and fisheries production. In recent years, Enterocytozoon hepatopenaei (EHP) has emerged as a major pathogen of the Pacific white shrimp Penaeus vannamei in many Asian countries (Vietnam, China, Indonesia, Malaysia, Thailand, India, and Korea). In Latin America, only in Venezuela, and to date, there is no report of its presence in Mexico. It is transmitted directly from shrimp to shrimp by oral or fecal means, cannibalism, or exposure to contaminated water. Hepatopancreatic microsporidiosis (HPM) is mainly associated with stunted growth and severe infections that can cause a poor production cycle, mortality, and problems in larva-producing laboratories. This review aims to overview the main microsporidian parasites and diseases found in white shrimp, including the clinical signs, control and prevention measures for EHP infection, and the detection of HPM using different techniques. In order to offer timely detection tools, different techniques are available for the detection and study of microsporidia. Such as optical microscopy, transmission electron microscopy, and histology; however, for diagnostic purposes, molecular methods are preferred due to their sensitivity, specificity, and short-time analysis. Our review suggests that constant monitoring in shrimp hatcheries and farms is essential to avoid the entry or transference of infected organisms, affecting shrimp production and the ideal development of healthy shrimp.

ABSTRACT Microalgae are a promising solution in shrimp farming overexploitation. This study assessed the efficacy of microalgae as a food additive for Penaeus vannamei growth and their effect on immune system stimulation against Vibrio parahaemolyticus. Three diets were formulated with 0, 1, and 3% (DC, D1, and D3, respectively) of a mixture of three different microalga species, Tetraselmis suecica, Dunaliella salina, and Chaetoceros muelleri, and growth, survival, and post-harvest quality in shrimp culture were evaluated. Two bioassays were performed: a 60-day feeding trial and an immersion infection bioassay against V. parahaemolyticus. D1 was the best treatment and significantly different to DC (P ≤ 0.05), achieving a food conversion factor of 1.24 ± 0.11 and 1.85 ± 0.38; specific growth rate 1.58 ± 0.03% d−1 and 1.35 ± 0.11% d−1; and weight gain of 5.68 ± 0.32 g and 4.79 ± 0.33 g, respectively. Protein content in shrimp muscle was positively increased by microalgae inclusion, achieving 20.8 ± 0.2% (D1) to 21.7 ± 0.3% (D3), 19.2 ± 0.1% (DC). In the infection bioassay, D1 and D3 reached a 100% survival rate, and histological damage in the hepatopancreas was not observed, suggesting immune system stimulation. These results indicated that microalgae added to food are an excellent source of proteins, carbohydrates, lipids, and promoters of antimicrobial activity that allowed additional protection against mortality caused by V. parahaemolyticus.

ABSTRACT This research study tested the protective effect of prolonged exposure of shrimp food supplemented with glucans from shrimp-pond related yeasts on shrimp Penaeus vannamei reared under the presence of the white spot syndrome virus (WSSV). The glucans extracted and purified from isolated marine yeasts identified as Debaryomyces hansenii, Candida tropicalis, Candida humilis, Candida glabrata, Pichia kudriavzevyi, Wickerhamomyces anomalus and the terrestrial Saccharomyces cerevisiae yeast were characterized by the Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The treatments were prepared with food enriched with the yeast beta-glucans and the control groups without beta-glucans. Shrimp were fed thrice a day and challenged orally with WSSV on days 31, 54, 66 and muscularly at day 70. The animals were assessed for the protective effect in terms of post-infection total hemocyte counts, and survival rate. The results indicated that marine yeasts possessed ß-1,3/1,6-glucans, and that D. hansenii was an excellent source yielding 30% of its dry biomass of pure glucans. For the positive control group where no glucans were added, WSSV challenges showed 100% survival when the virus was provided orally, and 40% when the virus was injected. These results also indicated that the shrimp line selected for this study was a resistant line for WSSV. Shrimp groups fed with glucans of the marine yeasts D. hansenii and C. humillis showed a significant protection, allowing shrimp survival of 66% while terrestrial yeast showed 57.14%. These results indicated that marine yeasts growing in the shrimp pond were an excellent source of beta-glucans that allowed extra protection against the mortality caused by this pathogenic virus.

ABSTRACT: Host genetics and diet can exert an influence on microbiota and, therefore, on feeding efficiency. This study evaluated the effect of genetic line (fast-growth and high-resistance) in Pacific white shrimp ( Litopenaeus vannamei ) on the hepatopancreatic microbiota and its association with the feeding efficiency in shrimp fed with diets containing different protein sources. Shrimp (2.08 ± 0.06 g) from each genetic line were fed for 36 days with two dietary treatments (animal and vegetable protein). Each of the four groups was sampled, and the hepatopancreatic metagenome was amplified using specific primers for the variable V4 region of the 16S rRNA gene. The PCR product was sequenced on the MiSeq platform. Nineteen bacterial phyla were detected, of which Proteobacteria was the most abundant (51.0 – 72.5 %), Bacteroidetes (3.6 – 23.3 %), Firmicutes (4.2 – 13.7 %), Actinobacteria (1.9 – 12.1 %), and Planctomycetes (1.3 – 9.5 %). Diet was the most influential factor in the taxonomic composition of the microbiota, while genetic line was not a strong influential factor. The results suggest that the taxonomic profile of the bacteria colonizing shrimp hepatopancreas was determined by the diet consumed, similar to what occurs in the intestine. Shrimp in the fast-growth line had greater feeding efficiency regardless of the diet supplied. Finally, the results suggest that Proteobacteria influenced ( p < 0.05) the feeding efficiency of shrimp fed with a vegetable diet. Nevertheless, further studies are required to explore how shrimp genetic line–diet interaction influences microbiota for probiotic development and functional food formulation for farmed shrimp according to the genetic line.

ABSTRACT This short-term study evaluated the effect of non-lethal high CO2 concentration on the transcriptional response of immune-related genes of Pacific white shrimp (Litopenaeus vannamei) cultured in recirculating aquaculture systems (RAS). Two experimental groups were created: high CO2 (47.67±2.04 mg L−1) and low CO2 (2.0±1.93 mg L−1). Shrimp of 8.85±1.20 g were placed randomly at a density equivalent to 100 individuals m−3 and were monitored at 6, 12, 18, and 24 h. The transcriptional response of immune-related genes was analyzed by qPCR. Gene expression of hemocyanin, prophenoloxidase, and heat shock protein 60 was downregulated at 24 h, suggesting affectations on oxygen transportation, melanization, and protein functioning of L. vannamei under high CO2 concentrations. Also, gene up-regulation of lipopolysaccharide- and β-glucan-binding protein and cytosolic manganese superoxide dismutase can impair the bacterial recognition and antioxidant defense of shrimp exposed to high CO2 concentrations. These results suggest that concentration at about 47 mg L−1 of CO2 can significantly influence the transcriptional response modulation of immune-related genes.

Abstract The increase in shrimp aquaculture production relates to the development of increasingly efficient formulated feeds and feed management strategies. Protein, considered the most important ingredient in feeds, represent the highest economic and environmental cost. Therefore, determining the appropriate amount of protein is essential to maintain a balance between performance, cost, and environment in aquaculture systems. The objective of this study was to determine the mathematical functions of Daily Protein Intake (DPI), to evaluate feeds with different Carbohydrate/Crude protein (CBH:CP) ratio and low inclusion of fishmeal for L. vannamei juveniles culture. The adjusted mathematical function that best represented aquaculture feeding practices was DPI=44.7(BW)-0.714. In the first experiment, four variants of DPI (80, 100, 120 and 140 %) at a constant CBH:CP ratio was carried out, finding the best performance at 120 %. In the second experiment, diets with five levels of CBH:CP (g CBH: g crude protein; 2.1, 1.5, 1.1, 0.8 and 0.6) with constant Lip:CP were evaluated using the same DPI function. The CBH:CP levels variation had a significant effect on growth parameters, feed conversion rate, nitrogen retention and protein, determining that feed with 2.1 CBH:CP ratio presents the best results when using DPI=53.64(BW)-0.714.

Resumen El aumento de la producción acuícola de camarón se ha logrado gracias al desarrollo de alimentos balanceados y estrategias de alimentación más eficientes. La proteína es considerada el insumo más importante para el desarrollo de los organismos, y representa el mayor costo económico y ambiental. El objetivo de este estudio fue determinar las funciones matemáticas de ingesta diaria de proteína (IDP), con objeto de utilizarlas para evaluar dietas con diferentes proporciones de carbohidratos/proteína cruda (CHO:CP) y baja inclusión de harina de pescado en juveniles de L. vannamei. El modelo matemático que representó de mejor manera las prácticas de alimentación acuícolas evaluadas fue IDP=44.7(PC)-0.714. En el primer experimento se utilizaron cuatro niveles de variación de IDP (80, 100, 120 y 140 %) a una proporción CHO:CP constante, encontrando el mejor rendimiento con IDP 120 %. En el segundo experimento; se evaluaron dietas con cinco niveles de CHO:CP (g CHO:g proteína cruda; 2.1, 1.5, 1.1, 0.8 y 0.6) usando la mejor función de IDP. La variación de los niveles de CHO:CP tuvieron un efecto significativo en crecimiento, el factor de conversión alimenticia, retención de nitrógeno y eficiencia proteica, determinando que la dieta con CHO:CP de 2.1 presentó mejores resultados con IDP=53.64(PC)-0.714.

ABSTRACT The present study was focused on assessing the effect of diets formulated with different sources and levels of protein on the production response of white leg shrimp Penaeus vannamei farmed at low salinity (3 g L-1). The protein sources were: soy meal (SM) and fish meal (FM), included at three levels: low (22-25%), medium (32-35%), and high (41-45%). A bioassay of 49 days was done in experimental tanks of 100 L (three tanks per treatment). Juvenile P. vannamei having a mean weight of 1.41 ± 0.30 g were stocked at a density of 100 ind m-3. Shrimp fed diets formulated with FM recorded significantly higher weight gain, specific growth rate (SGR), and protein assimilation efficiency rate (PER). Additionally, it showed a higher concentration of essential amino acids like methionine and threonine, and higher ash, calcium, iodine, phosphorous, and sodium content, which could favor the growth and survival of shrimp. Regression analysis showed that the optimum protein levels for diets formulated with SM and FM were 34.8 and 29.3%, respectively. These findings may help shrimp farmers to implement better feeding strategies for P. vannamei farmed at low salinity and on the use of alternative ingredients to substitute fish meal in the formulated feed.

White spot syndrome virus (WSSV) is the viral pathogen with the most negative impact on shrimp farming. In Sonora, Litopenaeus vannamei culture has decreased 50% during 2010-2012 due to WSSV outbreaks. The ORF94 has proven to be most useful for the analysis of WSSV variability. Several studies have suggested a correlation between its Repeat Units (RUs) and WSSV virulence as follows: the fewer RUs (<9) the higher mortality rate. In order to support this, we analyzed shrimps from eight farm periods and identified the WSSV-variety present in each one. In outbreaks, the presence of <8 RUs with a dominance of 3 RUs was notable in the last four years. Although it is still not clear how host-virus interactions and pond's environment affect the transition of the infection just from the presence of the virus in shrimps to an outbreak, these results are a step forward in understanding the pond status and ways of predicting the likelihood of a WSSV infection becoming an outbreak.

El virus del síndrome de la mancha blanca (VSMB) es un patógeno viral que impacta negativamente la producción de camarón de cultivo. En Sonora, el cultivo de camarón Litopenaeus vannamei disminuyó un 50% durante el período 2010-2012 debido a las mortalidades ocasionadas por la presencia del VSMB. El ORF94 es una región minisatélite muy usada para determinar la variabilidad genómica del virus. Varios estudios han sugerido una correlación entre sus unidades repetidas (UR) y la virulencia de VSMB: a menor UR (<9) mayor frecuencia de mortalidad. Para soportar esta hipótesis, se analizaron camarones de ocho ciclos de cultivo y se identificaron variantes del VSMB presente en cada uno de los ciclos. En ciclos con mortalidades masivas se notó la presencia de UR <8 con una dominancia de 3 UR en los últimos cuatro años. Aunque no está muy claro, la interacción VSMB-hospedero y como afectan los parámetros ambientales de las granjas en la transición de la sola presencia del VSMB a causar mortalidades masivas, estos resultados son solo un avance en el entendimiento de como una infección por el virus puede ocasionar un brote de la enfermedad con mortalidades masivas.

Almaco jack, Seriola rivoliana as well as some related species is of great interest in marine fish aquaculture. However, there are few studies about their reproduction in captivity. In this research work, reproductive performance and egg quality in two groups of adult Seriola rivoliana, caught in the wild and domesticated-F1 analyzed and compared, reared under optimal maturation conditions in a commercial private Laboratory. A total of 28 wild adult (>5 kg) were caught at La Paz Bay, Baja California Sur, Mexico, and 30 adult domesticated-F1 broodstock (>5 kg), were obtained from an original stock of 1,000 juveniles (3.5 g body weight) produced at Kona Blue (Hawaii, USA) sea farm. Fishes were transported to the Rancheros del Mar commercial private hatchery, where they were grown to adult size. Both groups were evaluated during eight months (May to December 2012) and compared in terms of reproduction performance (total number of spawning events, monthly spawning frequency, total number of eggs, total number of eggs per mL, and fertilization rate), egg biochemical composition (total proteins, total lipids, total carbohydrates, and triacylglycerides) and egg diameter. Results indicated that wild caught broostock showed a better reproductive performance in terms of fertilization rate, total number of spawning, monthly spawning frequency and total number of eggs produced. However, biochemical composition and egg diameter did not show statistical differences (P < 0.05) between two groups. The reproductive performance of broodstock and quality of eggs analyzed in this study are important traits to improve the aquaculture management of this species.

El jurel Seriola rivoliana así como algunas especies relacionadas, son de gran interés en la acuicultura de peces marinos. Sin embargo, existen pocos estudios sobre su reproducción en cautiverio. En este trabajo se analizó y comparó el desempeño reproductivo y calidad del huevo en dos grupos de adultos de Seriola rivoliana, capturados en el medio silvestre y domesticados-F1 criados en óptimas condiciones de maduración en un laboratorio comercial. Un total de 28 adultos silvestres (>5 kg) se capturaron en la Bahía La Paz, Baja California Sur, México y 30 adultos de origen domesticado-F 1 (>5 kg), se obtuvieron a partir de un lote de 1.000 juveniles (3,5 g de peso) producidos en la empresa Kona Blue (Hawái, EE.UU.) y transportados a la empresa Rancheros del Mar para su engorda y posterior maduración. Los reproductores de ambos orígenes, fueron evaluados durante echo meses (mayo a diciembre 2012) y comparados en términos de desempeño reproductivo (número de desoves totales, frecuencia mensual de desoves, número total de huevos, número total de huevos por mL, tasa de fertilización) y composición bioquímica del huevo (proteínas totales, lípidos totales, carbohidratos totales y triglicéridos), así como el diámetro del huevo. Los resultados obtenidos, indican que los reproductores de origen silvestre presentaron un mejor desempeño reproductivo en términos de porcentaje de fertilización, número total de desoves, frecuencia mensual de desoves y número total de huevos producidos. Sin embargo, la composición bioquímica y el diámetro del huevo no mostraron diferencias estadísticas (P < 0,05) entre los dos grupos. El desempeño reproductivo y la calidad de los huevos analizados en este estudio son aspectos importantes para mejorar el manejo en cautiverio de esta especie.

Abstract: New sequencing technologies and analytical capabilities have stimulated the study of microbial communities from specific environments, enabling researchers to understand the complexity of those systems. The 16S rRNA gene has proved very useful in describing the diversity and characterization of marine microbial communities, particularly of uncultivated organisms. The development of new sequencing techniques has contributed to the exponential increase in the number of reported 16S rRNA sequences as barcodes for microorganisms, forcing a review of concepts and methods for the taxonomic classification of these organisms. Manipulation and analysis of large amounts of genetic information have prompted the development of specific databases, specialized algorithms, and computational tools to compare thousands of such sequences and make a taxonomic assignment. Complete 16S rRNA sequences are thus needed for accurate and reproducible taxonomy assignment in the study of marine bacterial communities.

Resumen: Las nuevas tecnologías de secuenciación y capacidades analíticas han estimulado el estudio de las comunidades microbianas de ambientes específicos, lo cual ha permitido conocer la complejidad de estos sistemas. El gen ARNr 16S ha demostrado ser de gran utilidad para describir y caracterizar las comunidades microbianas marinas, especialmente los organismos no cultivados. Las nuevas técnicas de secuenciación han contribuido al incremento exponencial de registro de secuencias, aunque parciales, del ARNr 16S como elemento de código de barras para microorganismos. Consecuentemente, ha sido necesaria una revisión de conceptos y métodos de clasificación taxonómica para estos organismos. El manejo y análisis de una gran cantidad de información génica han impulsado el desarrollo de bases de datos específicas, algoritmos y herramientas computacionales especializadas para comparar miles de secuencias semejantes y hacer la asignación taxonómica. Por lo tanto, las secuencias completas del ARNr 16S son necesarias para una asignación taxonómica certera y reproducible en los estudios de comunidades microbianas marinas.