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.

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.

Crustacean shells are composed of chitin, which is bound to protein and minerals, along with other essential nutrients. These components are necessary for growth, immune response, the formation of reproductive structures, and the enhancement of sperm quality. This study aimed to evaluate the effects of prawn shell meal diets on hemocyte count, hemolymph clotting, and sperm quality of the freshwater prawn Macrobrachium caementarius . The prawns were distributed into three dietary treatments, consisting of a basal diet (control) and two experimental diets supplemented with 20% raw prawn shell meal (RPSM) and 20% cooked prawn shell meal (CPSM). Hemocytes were counted, and the hemolymph clotting time was determined. Spermatozoa in spermatophores and the vas deferens were counted. Sperm quality was assessed by staining. The RPSM and CPSM diets did not lead to an increase in hemocytes, nor did they affect the clotting time of the hemolymph. However, with the RPSM diet, there was an increase in the number of normal spermatozoa in the entire vas deferens (from 3.65–8.11 × 10 ⁵ spz/mL) and a lower proportion of dead and abnormal spermatozoa (<2 × 10 ⁵ spz/mL). These findings suggest the potential of RPSM and CPSM diets to improve sperm quality in the freshwater prawn. Further research based on isoproteic and isolipidic diets should be performed to ascertain whether RPSM could increase reproductive performance in male individuals of the freshwater prawn.

La disposición de fósforo en los océanos es una de las principales causas de contaminación de los ecosistemas marinos, con severos impactos sobre la vida acuática y por lo cual urge desarrollar medidas de mitigación. En este estudio, se evaluó el uso de la microalga Tetraselmis suecica para remover fósforo (P) del agua marina. Se emplearon tratamientos experimentales de 23.03, 44.80, 79.50 y 94.20 mg L-1 de (NH4)2 HPO4 y un control con medio Heussler-Merino (HM). Las unidades de cultivo consistieron de fotobiorreactores (2000 mL) conservados con aireación e iluminación constante. Durante el cultivo, las unidades mantuvieron crecimientos similares, sin embargo, los controles presentaron mayores tasas de crecimiento. Al final del experimento, los porcentajes de remoción disminuyen con el aumento de la concentración del P, con valores de 77.83 % en los controles y 36.20 % en los dosificados con 94.2 mg L-1 de P. Estos resultados demuestran las excelentes posibilidades de utilizar cultivos masivos de T. suecica, para remover el exceso de P del ambiente acuático marino.