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

This study aimed to map the world's scientific production of bacterial and fungal microbiota in mollusks. The research was carried out in the Web of Science database, using "Fungi AND Mollusk" and "Bacteria AND Mollusk" descriptors and publication time between 2001 and 2021. Indexes were built by years, countries, research areas, and two maps of the co-occurrence of terms. There was a progressive increase in the production of microbiota in mollusks, with more research on bacteria during the investigated period. China and USA were the countries with the highest percentage of publications. Research with fungi and bacteria accounted for 28.41 and 17.66% in China, respectively. While the USA, the percentage was 21.05% for fungi and 16.02% for bacteria. Areas such as marine and freshwater biology (24.77%), fisheries (23.86%), biochemistry and molecular biology (18.60%), and pharmacy (17.83%) showed a higher percentage of indexed articles. There was also a high concentration of deposits of publications in the immunology area for both themes. The groups formed for bacteria and fungi indicated that studies had described the immune responses of mollusks, the genetic aspects associated with their defense mechanisms, pathogen virulence factors, and symbiotic and pathogenic microbiota, highlighting genera Vibrio, Aspergillus, and Escherichia coli pathogenic pathotypes. The bacterial and fungal microbiota in mollusks have been studied in several areas of knowledge and have given rise to research that can support the proper management of mollusks, application in the pharmaceutical industry, and implementation of measures in public health.

A 70-day experimental trial was performed to evaluate the contribution of biofloc to the nutrition of Macrobrachium rosenbergii 15 days old postlarvae (PL) (average 82.00 ± 19.71 mg) fed different crude protein (P) and lipids (L) levels in zero-water exchange culture tanks. Six biofloc treatments (BFT) as experimental diets with 15, 20, or 25% P levels and 5 or 8% L levels were managed: BFT-15/5; BFT-15/8; BFT-20/5; BFT-20/8; BFT-25/5; BFT-25/8, and a clear-water control without biofloc fed with 25% P and 8% L (CW-25/8). The experiment was done in triplicate in 21-60 L plastic tanks containing 10 prawns tank-1. At the end of the experiment, survival of prawns was above 66%, with no significant differences among experimental groups (P > 0.05). The best growth performance was observed in the experimental prawns maintained in BFT-20/5, BFT-20/8, BF-25/5, and BFT-25/8 compared to the control (P < 0.001). The feed conversion rate of the prawns in BFT-20/5 was significantly lower than that in control (P < 0.001); the best P efficiency ratio and productive P value were observed in all BFT compared to control prawns (P < 0.001). Results showed that it is feasible to use low concentrations of P (20%) and L (5%) in diets to grow giant freshwater prawn PL in a biofloc system. Results also demonstrated that biofloc contributes to the P and L requirements of cultured freshwater prawn PL, as indicated by improved feed utilization, P retention, and growth performance.

The biodiversity of epibenthic communities in rocky reefs in the Mexican tropical Pacific has been studied minimally during the past three decades. This study describes the abundance and distribution of algae and invertebrates in a deep rocky reef from this region. Samples were taken at 20 m depth in 2012 by randomly placing 50×50 cm quadrats. Also, photographs were taken of each quadrat to quantify the coverage of organisms. Throughout the study, the algae were the most abundant group (17748.5 cm m-2), of which encrusting calcified (6350.9 cm m-2), turf (3040.3 cm m-2), and larger-sized articulated corallines (2700.9 cm m-2) had the highest coverage. Regarding invertebrates, zoanthids (1153.3 cm m-2) and corals (746.7 cm m-2) had high coverage. All of the algal groups were found on vertical and horizontal substrates. The detrended correspondence analysis showed that larger-sized articulated corallines and encrusting not calcified groups were prevalent on the horizontal substrate and corals on the vertical substrate. These abundance and distribution patterns represent the first quantitative study of rocky reefs from the region. Considering the rapid influence of human activities in this coastal zone and the fact that rocky reefs have been minimally studied, there is a clear need for long-term monitoring programs to establish reef communities' patterns and processes, which are useful in conservation programs.

Chilean hake (Merluccius gayi gayi) is one of central Chile's most important demersal resources, and its fishery involves an artisanal fleet that mainly uses gillnets. In the recent history of the fishery, there has been a decrease in catch sizes and a progressive reduction in mesh sizes. This study aimed to analyze the factors that influenced the mean catch sizes of Chilean hake between 2001 and 2018 to understand this situation, correlating the response of fishermen with the capture efficiency of the nets used. Applying a generalized linear model, a significant effect of the factors year, port (zone), and mesh size were observed on the mean size of individuals caught. The model explained 85% of the deviation, the greatest relative contributions being made by the factors year (53.6%) and port (30.2%). A lower effect was estimated for the mesh size factor with 1.2% deviance. These findings suggest that the progressive reduction in mesh sizes is associated with a response to the demographic change in the stock. Differentiated management measures by zones could be considered in the fishery, given the estimated differences.

The current study aimed to investigate the ectoparasitic diversity and gill alterations in Hoplerythrinus unitaeniatus (Characiformes: Erythrinidae) and Cichlasoma bimaculatum (Perciformes: Cichlidae) and evaluate the microbiological and physicochemical quality of water samples deriving from a Quilombola zone in Maranhão State, Brazil. Water samples and 42 fish specimens, 21 H. unitaeniatus and 21 C. bimaculatum, were collected from a floodable environment. Water samples were subjected to physicochemical and microbiological analyses in the laboratory environment. Fish specimens were euthanized to collect and identify ectoparasites in animals' mucus, body surface, and gills, as well as to enable the histological analysis of the second right gill arch. The herein-identified ectoparasites have shown 30.95% prevalence and comprised three phyla: Platyhelminthes, Trematoda and Arthropoda. The herein-identified main histological changes comprised incomplete and complete fusion of several lamellae, lifting of respiratory epithelium, lamellar disorganization, lamellar epithelial hyperplasia, and blood sinus dilation. The herein calculated histological alteration index has shown that 23.80% of specimens presented mild-to-moderate tissue damage, 4.77% presented moderate-to-severe tissue changes, and 9.52% presented irreparable tissue damage. It was possible concluding that histological gill lesions identified in fish specimens analyzed may be adaptive responses to the affected environment and the incidence of ectoparasites.

This study investigated the effect of acclimation temperatures and eyestalk ablation (EA) on the thermal tolerance of juvenile Penaeus vannamei. In each case, the relative expression of genes involved in cell protection (hsp70 and hsp90), oxidative stress (cMnSOD and GPx), and anaerobic metabolism (hif1a) was assessed. For this purpose, shrimp were acclimated to 20, 26, and 32°C for 21 days. After acclimation, the critical thermal maxima (CTmax) was determined in non-eyestalk ablated, unilaterally, and bilaterally eyestalk ablated organisms. An effect of acclimation temperatures on CTmax values was observed, with shrimp acclimated at 32°C having the highest rates. Likewise, EA resulted in lower thermal tolerance to CTmax in organisms acclimated at 20 and 26°C. The shrimp's protective and cellular repair responses were evidenced by increased hsp70 and hsp90 gene expression after CTmax and were intensified by the EA. In contrast, the results showed that cMnSOD was very sensitive to CTmax, and its expression was intensified with EA, while for GPx, there was an increase in the relative gene expression, mainly in shrimp acclimated at 20°C. In the case of hif1a, overexpression was observed at the acclimation temperature of 26°C, showing the activation of compensatory mechanisms such as anaerobic metabolism. EA caused a significant molecular response during CTmax of molecular biomarkers involved in heat stress response, oxidative stress, and compensatory mechanisms.

We characterized the surf-zone fish assemblage structure of an ocean beach on the central coast of Brazil (Guriri Beach, Espírito Santo) and assessed its diel variability. Like the entire Espírito Santo coast, Guriri Beach was also affected by ore tailings from the Fundão dam, which collapsed on November 5, 2015. Monthly samplings were carried out before the dam collapse along a year cycle (May 2013-April 2014), during the day and night in the neap tide, using a beach seine. A total of 2217 specimens were caught (1017 during the day and 1200 at night), distributed in 36 fish species and 20 families. Juveniles of the kingcroaker Menticirrhus spp., great pompano Trachinotus goodei, Florida pompano Trachinotus carolinus, littlescale threadfin Polydactylus oligodon, and Atlantic sabretooth anchovy Lycengraulis grossidens dominated the fish fauna, accounting for 84% of the total capture. The fish assemblage structure changed irregularly between day and night throughout the year. P. oligodon and Menticirrhus spp. were more abundant at night, whereas T. carolinus and L. grossidens were more abundant during the day. In most cases, no significant change was detected in fish abundance and richness between the day and night; when significant differences were detected, abundance and richness were higher at night. Our findings could support a monitoring program of the local surf-zone fish fauna and serve as before-impact data, allowing more accurate quantification of the ore tailings' impacts on the local fish biodiversity.

This study aimed to evaluate the development and the increase in the skin pigmentation of the organism Heros severus cultured in a biofloc system with diets enriched with carotenoid pigments. The culture was made in 80 L water tanks with 20 juvenile organisms of H. severus; each treatment was made by duplicate. Four experimental diets were used: a) trout feed, El Pedregal®; b) TetraColor®; c) carrot and d) beetroot. The diet that obtained the highest values regarding the growth of the fish was the control diet. Regarding the coloration of the fish, the beetroot diet was the diet that presented the highest values with 9.55 μg of total carotenoids in tissue, presenting significant differences (P = 0.001) concerning the other diets, proving that a diet based on beetroot can be a good option for the culture of ornamental fish. Because it allows the organisms to have a survival rate above 90%, have similar growth to the control group, and a significant improvement in coloration, being a natural carotenoid low-cost source to improve the commercialization of organisms. Nevertheless, it did not present significant differences (P = 0.005) regarding beetroot and TetraColor® diets, while it presented significant differences with the carrot diet.

The sea cucumber Holothuria (Halodeima) grisea Selenka, 1867 is distributed from Florida (USA) to southern Brazil. Juveniles of this species are very hardly found in the wild. H. (H.) grisea is very common on sandstone reefs in some localities from the northern coast of Brazil. Because seagrass beds are a conspicuous feature in some of these localities, the authors have speculated that juveniles live in these habitats. Following this species' reproduction period, seagrass beds adjacent to sandstone reefs were inspected in search of juveniles from December to May. Sea cucumbers were found in one of them. Individuals were collected from two areas within the seagrass bed and two areas within neighboring rocky shores, and their contracted body lengths were measured. Mean sizes were significantly smaller in the seagrass areas than in reef areas (post-hoc Tuckey test, P < 0.05). Within the seagrass bed, more than 70% of individuals were smaller than 7.5 cm, whereas 84.9 and 93.3% in the two reef areas were larger than 7.5 cm -the first report of an H. (H.) grisea population dominated by juveniles. Therefore, seagrass meadows should be looked at as possible sources of juveniles for adult populations of H. (H.) grisea in the tropical western Atlantic. Also, given the rarity of juvenile sightings for this species anywhere within its distribution range, the results are very meaningful for future research on its ecology and local and regional fishery management.

&nbsp; This paper analyzes the electoral political contexts in Mexico and Michoacán during the turning point of 1940 presidential succession. It also analyzes the development of a tragic event of political violence – where fourteen peasants died – that occurred in the town of Huetamo, which reflected the dispute for power between national level candidates: Manuel Ávila Camacho of the Party of the Mexican Revolution and his contender Juan Andreu Almazán of the Revolutionary Party of National Unification. These two candidates ran an intense electoral campaign with displays, public demonstrations, reciprocal rejection, warnings, and confrontations between small groups, in addition to both naming themselves heirs of the Mexican Revolution. Based on the analysis of several documentary files of the agents of the Directorate of Political and Social Investigations of Mexico’s Ministry of the Interior (Secretaría de Gobernación) and other contemporary testimonies, an attempt is made to clarify the causes that gave rise to the Huetamo ‘zafarrancho’, whose participants clashed over political differences. In addition, we discuss some possible reasons for the historical obscurity of this crime, for which was no judicial investigation or punishment of the intellectual and material authors.