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The purpose of the present research was to evaluate the effect of diets supplemented with activated yeast, crude chitin, and chitosan on the growth, immune, and antioxidant response of freshwater prawn Cryphiops (Cryphiops) caementarius. Adult male prawns were kept in individual culture vessels installed in aquarium tanks. The basal diet (control) was supplemented with activated Saccharomyces cerevisiae yeast (60 g/kg), crude chitin (20 g/kg), and chitosan (1 g/kg). Each dietary treatment consisted of three replicates. The diet supplemented with activated yeast causes greater growth, as well as a greater number of total hemocytes (82.54 × 105 cells/mL), semigranular (59 × 105 cells/mL), and granular (18.67 × 105 cells/mL) hemocytes and without atypical hemocytes. Furthermore, a higher number of hemocytes positive for prophenoloxidase (98%), a shorter hemolymph clotting time (42.87 s), a higher activity of acid phosphatase (12.50 U/mL) and glutathione-S-transferase (GST) (0.186 U/mL) were also observed in dietary yeast group. On the contrary, there were no differences in the activity of superoxide dismutase (SOD) enzyme in prawns from any dietary treatment. Results from this research demonstrate for the first time that the diet containing activated yeast increases the growth and immune response of the freshwater prawn through a significant increase in hemocyte and acid phosphatase levels, a decrease in hemolymph clotting time, and a greater number of proPO-positive hemocytes. However, activated yeast is not effective in increasing the activity of antioxidant enzymes SOD and GST. Therefore, the activated yeast diet can be useful to improve the aquaculture production of C. (C.) caementarius and possibly of other commercially important crustaceans.

Paralichthys adspersus is a native species from the Pacific coast of South America that is of great economic importance for Peruvian aquaculture. Even though establishing sustainable farming depends on avoiding irreversible damage to the population gene pool due to processes such as inbreeding, studies focusing on genetically characterizing farmed stocks are yet to be documented. By using ten microsatellite loci on captive and wild individuals of P. adspersus, we successfully characterized the only commercial broodstock of this species in Peru by means of determining the genetic diversity and inferring relatedness. Although most microsatellite loci showed deviations from Hardy-Weinberg equilibrium, the genetic diversity levels in the commercial broodstock were considered healthy compared to those obtained for a wild population, with an average number of alleles of 17.40, an effective number of alleles of 9.14, and an observed and expected heterozygosity of 0.49 and 0.87. No significant differences between the broodstock and the wild population in terms of genetic diversity were observed. The fixation index and analysis of molecular variance also indicated a low rate of differentiation between both populations. In relatedness estimation, the analysis based on five method-of-moment estimators and a maximum-likelihood estimator showed the category “unrelated” as being the most probable relationship among the individuals within the commercial broodstock. Our findings reveal the conservation of genetic diversity in this population and outline potential breeding strategies that hatchery managers could use to minimize the loss of genetic diversity and long-term inbreeding. This could help establish proper genetic management in captive populations of P. adspersus and should apply to other captive stocks where pedigree information is lacking.

Abstract Objective The advancement of molecular techniques in an era in which high-throughput sequencing has revolutionized biology renders old-fashioned alternatives to high-throughput methods obsolete. Such advanced molecular techniques, however, are not yet accessible to economically disadvantaged region-based laboratories that still obtain DNA profiles using gel-based techniques. To explore whether cost-efficient techniques can produce results that are as robust as those obtained using high-throughput methods, we compared the performance of polyacrylamide gel electrophoresis (PAGE)- and capillary electrophoresis (CE)-derived genomic data in estimating genetic diversity and inferring relatedness using 70 individuals of fine flounder (Paralichthys adspersus) selected from a hatchery population and genotyped for five microsatellite loci. Results Here, we show that PAGE- and CE-derived genomic datasets yield comparable genetic diversity levels regarding allelic diversity measures and heterozygosity. However, relatedness inferred from each dataset showed that the categorization of dyads in the different relationship categories strongly differed. This suggests that while scientists can reliably use PAGE-derived genomic data to estimate genetic diversity, they cannot use the same for parentage testing. The findings could help laboratories committed to population research not be discouraged from using the PAGE system if high-throughput technologies are unavailable and the method is adequate to address the biological question.

Early detection of non-indigenous species is crucial to reduce, mitigate, and manage their impacts on the ecosystems into which they were introduced. However, assessment frameworks for identifying introduced species on the Pacific Coast of South America are scarce and even non-existent for certain countries. In order to identify species’ boundaries and to determine the presence of non-native species, through morphological examinations and the analysis of the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL-5P) gene, we investigated the phylogenetic relationships among species of the class Florideophyceae from the coast of Ancash, Peru. The rbcL-5P dataset revealed 10 Florideophyceae species distributed in the following four orders: Gigartinales, Ceramiales, Halymeniales, and Corallinales, among which the Asian species, Melanothamnus japonicus (Harvey) Díaz-Tapia & Maggs was identified. M. japonicus showed a pairwise divergence of 0% with sequences of M. japonicus from South Korea, the USA, and Italy, the latter two being countries where M. japonicus has been reported as introduced species. Our data indicate a recent introduction event of M. japonicus in Peru, and consequently, the extension of its distribution into South America. These findings could help to adopt management strategies for reducing the spread and impact of M. japonicus on the Pacific Coast of South America.

El objetivo fue determinar la preferencia termal de machos adultos de Cryphiops caementarius previamente aclimatados a diferentes temperaturas. Los camarones se colectaron del río Pativilca. En laboratorio, los camarones se aclimataron durante 30 días en nueve acuarios, cada uno con 10 recipientes circulares. En cada recipiente hubo un camarón (10 por acuario). Las temperaturas de aclimatación fueron de 19, 24 y 28 °C. El sistema de gradiente de temperatura (12 a 33 °C) fue una canaleta de PVC (3 m de longitud y 10 cm de profundidad) con 18 compartimentos. En un extremo de la canaleta se colocaron termorreguladores sumergibles (100W) y en el otro extremo, bolsas con hidrogel congeladas. La preferencia termal se determinó por el método agudo y las pruebas se realizaron entre las 08:00 y 14:00 h. Los camarones aclimatados a 24 °C se desplazaron a compartimentos cuyas temperaturas fueron más altas que la temperatura de aclimatación. Los camarones aclimatados a 24 °C se desplazaron a compartimentos cuyas temperaturas fueron alrededor de la temperatura de aclimatación. Los camarones aclimatados a 28 °C se desplazaron a compartimentos donde las temperaturas fueron más bajas que aquella de aclimatación. La preferencia termal de los camarones aclimatados a 19 °C fue de 22.7 °C, y la de los aclimatados a 24 °C fue de 24.8 °C, ambos sin diferencias significativas (p>0.05). En cambio, en los aclimatados a 28°C fue de 21.1 °C, que solo difirió (p