Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Our knowledge of the reproductive biology of palaemonid shrimps is an important tool to assess potential candidates for aquaculture as well as being useful to develop adequate strategies for the conservation of the biodiversity. Here we analyzed the fecundity, volume and water content of the eggs, and the reproductive output (RO) of Macrobrachium tenellum in the Ameca River, Jalisco-Nayarit, Mexico. The total length of the females ranged from 26.6 to 67.0 mm (average 44.2 ± 8.8 mm) and fecundity (considering all stages) fluctuated between 253 and 10,384 eggs (average 2,418 ± 2,089 eggs). Females lost on average 26% of the initially produced eggs. The average egg length increased from 0.55 (recently produced eggs) to 0.66 mm (eggs close to hatching). The water content of eggs increased significantly during embryogenesis by 11.4%. The RO was not related to female length and fluctuated between 4.1 and 16.0%, which are values within the range reported for other decapods. The results of the current research contribute to laying the foundations for future studies that help to define strategies for the conservation and sustainable use of this crustacean.

The present research was focused to characterize the digestive proteases in Macrobrachium carcinus adults using biochemical and electrophoretic techniques. Our results showed that the alkaline proteolytic activity from males and females did not show significant differences (P > 0.05) between them, the optimum pH for digestive proteases is 8, and is very stable to changes in alkaline pH (8 and 10). The optimum temperature for alkaline proteases is 45ºC and is stable from 25 to 45ºC. The activity was totally inhibited with phenylmethylsulfonyl fluoride (PMSF), additionally the inhibition with trypsin soybean inhibitor 1 (SBT1) and tosyl-lysine-methyl ketone (TLCK) indicate high effect over serine proteases. Eight active bands were found using sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE) zymogram (range 17.8-94.0 kDa), which were partially inhibited with ovalbumin (Ovo), SBT1, phenanthroline (Phen), tosyl-phenylalanine-methyl ketone (TPCK), TLCK and ethylenediaminetetraacetic acid (EDTA), indicating an omnivorous digestive capacity, which remarks that the mainly alkaline protease in M. carcinus hepatopancreas are trypsin like enzymes.

Due to the cost of raw materials, the need to formulate balanced feeds with highly digestible ingredients is indispensable for the aquaculture feed industry. For this reason, the protein in vitro digestibility, assessed by the pH-stat method, of ingredients with potential of using them on the balanced feed for Macrobrachium tenellum, were evaluated. The relative protein digestibility was assessed in twelve feed ingredients, including animal (pork meal, feather poultry meal, prime poultry meal, turkey meal, fish meal, shrimp meal), vegetal (coconut paste, chickpea meal, soybean meal, wheat gluten) and microbial (yeast and Spirulina meal); casein (Hammerstein grade) was used as the reference protein. The highest relative protein digestibility was found in: Spirulina meal (52.6%); following by pork meal (45.6%), and feather poultry meal (39.6%). The lowest digestibilities were found in soybean meal (15.9%), chickpea meal (12.1%), and fish meal (11.6%). The protein digestibility value should be considered for selecting potential ingredients for the formulation of balanced feeds for M. tenellum.

The sexual maturation and reproduction of crustaceans are very demanding processes for energy and nutrients. Females require the nutrients to deposit them into the eggs and allow the healthy development of embryos and early larvae survival. The lipids are essential nutrients related to the sexual maturation and the egg production, as they are sources of metabolic energy for the gonad development, as well structural molecules for the embryonic tissue formation. This work presents the effects of different dietary lipid levels (10, 12.5, 15, 17.5 and 20% of a mixture of krill and cod liver oil as lipid sources), on the growth, egg production, and egg quality, of freshwater prawn Macrobrachium acanthurus females fed during 60 days. The results showed that an inclusion higher than 15% of lipids, improved the egg production and the content of protein and lipids significantly. A lipid inclusion between 15 and 17.5% might be optimal for maturation and egg production of the females of M. acanthurus.

ABSTRACT. The aim of this study was to evaluate the production of an aquaponic culture of white shrimp (Litopenaeus vannamei) and basil (Ocimum basilicum) using two sources of low-salinity water (1.7 g L-1): diluted seawater (DSW) and groundwater (GW) with zero water exchange at a stocking ratio of 4.9 shrimp per basil plant. Six aquaponic treatment systems were constructed: three individual aquaponic systems for DSW-basil, three for GW-basil, and a control (per triplicate) of basil only with hydroponic solution. Stock densities for shrimp were 75 PL m-2 and 16 plants m-2 for basil. With the exception of the yield in the shrimp culture (kg m-2 or t ha-1), no significant differences (P > 0.05) were found for the final individual weight, survival, growth rate and feed conversion ratio between DSW and GW, whereas for basil, lower yields were found with DSW. No significant differences in the basil production between the control and the GW were found. Feed consumption per kg of total harvested basil were significantly lower (P < 0.05) in GW treatment, while for feed intake in the shrimp farming, where no significant differences were found (P > 0.05). The aquaponic culture of shrimp and basil using these two types of low-salinity water sources showed promising results. The estimates of both crop yields were comparable with those recorded in the literature and for commercial field crops from northwest Mexico.

The natural nitrogen stable isotope signatures (δ 15N) found in poultry by-product meal (PBM) and fish meal (FM) were used to estimate the relative contribution of dietary nitrogen supplied by both ingredients to the somatic growth of juvenile channel catfish Ictalurus punctatus. Six isonitrogenous and isoenergetic experimental diets were formulated using FM and PBM. Two of these diets consisted of isotopic controls having only one ingredient supplying dietary nitrogen, either FM or PBM. Four combined diets were formulated with varying proportions of these ingredients in order to supply high proportions of PBM (FM:PBM, 50:50, 35:65 20:80 and 5:95) on a nitrogen basis. There were significant differences in mean final weight of fish at the end of the trial. Lower growth was observed as the dietary level of PBM increased. In order to determine the relative contributions of the dietary nitrogen supplied by FM and PBM to catfish growth, an isotopic mixing model was applied. Results indicated that the incorporation of dietary nitrogen supplied by PBM was equivalent to the die tary proportions. The dietary nitrogen available in combined diets containing 50, 65 and 80% of PBM was incorporated in fish bodies as 50, 62 and 81%, respectively. However, high incorporation of dietary nitrogen from PBM was not always reflected in higher growth rates. Results demonstrate the viable use of stable isotopes to determine the allocation of dietary nitrogen and indicate that practical diets for catfish can be formulated with levels of PBM as high as 65% without affecting growth and survival.

Different sources of microbial biomass have drawn attention as novel ingredients for aquaculture feeds. In the present study, isotopic measurements were applied to determine the contribution of dietary nitrogen supplied by two sources of microalgal biomass and fish meal, to the growth of shrimp Penaeus vannamei. Microalgae Schizochytrium sp. and Grammatophora sp. were isolated from the Sea of Cortez and massively cultured to obtain sufficient biomass. Experimental diets were formulated with low levels of microalgal biomass replacing 5 and 10% of fish meal nitrogen. Nitrogen stable isotope values were determined in ingredients, diets, and shrimp to estimate the relative contributions of the dietary nitrogen and dry matter supplied by these ingredients to the somatic growth. At the end of a feeding trial, significant differences were observed in mean final weight gain. Dietary nitrogen contributions from microalgae were similar to established dietary proportions, but when estimated on a dry matter basis, nutritional contributions were different for a diet containing 10% of Schizochytrium, which contributed 24% of dry matter to growth. Results demonstrate that low dietary inclusion levels of microalgal biomass elicit similar or higher growth rates than diets based on a fish meal only. Isotopic data indicated that microalgae actually contributed protein to tissue accretion.

White spot syndrome virus (WSSV) has damaged the Ecuadorian shrimp culture industry severely. The shrimp industry is highly important as it has generated high revenues over the past few years in Ecuador. Therefore, research on preventing devastating viral infections such as WSSV, is of major relevance. This study aimed to evaluate a potential adaptive immune response system in white shrimps (Penaeus vannamei) by using a vaccination method of inactive white spot virus (WSV) against an active WSV. A bioassay using 120 shrimps, 60 injected with inactive WSV and 60 injected with shrimp tissue without WSV infection, was conducted. Firstly, 30 specimens injected with inactive WSV were challenged against active WSV after 48 hours. The remaining 30 specimens were challenged against shrimp tissue without WSV infection, as a negative control.  Secondly, 60 specimens injected with tissue without WSV infection were challenged as follows: 30 against active WSV and 30 against shrimp tissue without WSV infection. Kaplan-Meier analysis (P £ 0.961) of the results showed no significantly differences between the groups. Thus, these results showed a non-prevention immune response effect in juvenile shrimps (P. vannamei) via injection.  

Boat engines increase the noise levels of the oceans, alter the acoustic environment of cetaceans and diminish their efficiency to echolocate. This study aims to determine if Guiana dolphins (Sotalia guianensis) are influenced by boat approaches. A land-based survey was conducted to record behavioral responses and count surfacing events of Guiana dolphins during 293 observation sessions from February to November 2014 in Pontal Bay, Ilhéus, Brazil. Ninety-eight behavioral responses to boat approaches of 93 dolphin groups were classified as negative (interruption or alteration of activity) or neutral (no response). The dolphins presented a neutral response to 90% of boats without engine approaches, 48% negative responses to inboard motorboat approaches, and 76% negative responses to outboard motor boat approach. Resting groups demonstrated 14 negatives and four neutral responses. Groups engaged in forage-feed activity presented ten negative and seven neutral responses while traveling groups exhibited 14 negative and 36 neutral responses. The average rate of surfacing events was significantly superior (P < 0.001) in the absence of boats (1.83 ± 0.90 surfacing events ind-1 min-1) than in their presence (1.34 ± 0.92 surfacing events/individual/minute). Guiana dolphins are exposed to an increasing number of anthropic perturbations and the evaluation of its behavioral responses to approaching boats is the first step to comprehend the real impact of boat encounters. Our results may contribute to the development of management strategies in estuarine areas to increase the conservation of the Guiana dolphins.

In this work we evaluated the essential amino acid profile of muscle Crocodylus acutus and calculated their chemical score of main proteins used in their diet in captivity. The separation and identification of amino acids was carried out by high performance liquid chromatography coupled to a fluorescence detector. The calculation of chemical score was obtained by dividing the value of each essential amino acid between the same amino acid of the reference protein. The lowest value of the relationships is the chemical score. The amino acids present in greater quantities in the tail muscle are glutamic acid, lysine and leucine (16.96, 9.84 and 8.87 g amino acid per 100 g of protein, respectively), whereas histidine, methionine and tryptophan (2.99, 2.93 and 0.59 g amino acid per 100 g of protein) were the lowest. The chemical score obtained results showed that the proteins of animal origin, preferably marine fish and supplemented with terrestrial animals ingredients, including beef liver appear to be the most effective. The incorporation of plant proteins in diets for C. acutus does not appear as a viable alternative due to deficiencies in several essential amino acids such as methionine, lysine and threonine. amino acids, chemical score, protein, crocodile, feeding, diet.