Synthesis and Optimization of Ni-Based Nano Metal-Organic Frameworks as a Superior Electrode Material for Supercapacitor.

Metal-organic frameworks (MOFs) are hybrid materials that are being explored as active electrode materials in energy storage devices, such as rechargeable batteries and supercapacitors (SCs), due to their high surface area, controllable chemical composition, and periodic ordering. However, the facile and controlled synthesis of a pure MOF phase without impurities or without going through a complicated purification process (that also reduces the yield) are challenges that must be resolved for their potential industrial applications. Moreover, various oxide formations of the Ni during Ni-MOF synthesis also represent an issue that affects the purity and performance. To resolve these issues, we report the controlled synthesis of nickel-based metal-organic frameworks (NiMOFs) by optimizing different growth parameters during hydrothermal synthesis and by utilizing nickel chloride as metal salt and H2bdt as the organic ligand, in a ratio of 1:1 at 150 °C. Furthermore, the synthesis was optimized by introducing a magnetic stirring stage, and the reaction temperature varied across 100, 150, and 200 °C to achieve the optimized growth of the NiMOFs crystal. The rarely used H2bdt ligand for Ni-MOF synthesis and the introduction of the ultrasonication stage before putting it in the furnace led to the formation of a pure phase without impurities and oxide formation. The synthesized materials were further characterized by powder X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), and UV-vis spectroscopy. The SEM images exhibited the formation of nano NiMOFs having a rectangular prism shape. The average size was 126.25 nm, 176.0 nm, and 268.4 nm for the samples (1:1)s synthesized at 100 °C, 150 °C, and 200 °C, respectively. The electrochemical performances were examined in a three-electrode configuration, in a wide potential window from -0.4 V to 0.55 V, and an electrolyte concentration of 2M KOH was maintained for each measurement. The charge-discharge galvanostatic measurement results in specific capacitances of 606.62 F/g, 307.33 F/g, and 287.42 F/g at a current density of 1 A/g for the synthesized materials at 100 °C, 150 °C, and 200 °C, respectively.

Fatal case of HBV-liver failure after withdrawal of antiviral treatment.

We report a case of fatal HBV reactivation in a patient with chronic hepatitis B infection HBeAg-, who was withdrawn from antiviral therapy.. We think that it may be a warning of risks that this clinical decision may entail.

Does sargassum contribute to meiofauna dispersal? The case of tardigrades and nematodes in the Mexican Caribbean.

The knowledge of the long-distance dispersal mechanisms of meiofauna is still limited. Rafting is considered as the main mechanism of dispersal of the meiofauna. The recent events of the Sargassum spp. arrival in the Caribbean provides the opportunity to explore long distance mechanisms. Four samples of floating Sargassum spp. were collected from the water column in Xcalak, Quintana Roo, which arrived at the Reef lagoon and Mangrove fringe. A total of 425 organisms were present, 388 nematodes, 36 tardigrades, and a single acarus. Tardigrades were represented by three species, whereas nematodes were represented by 16 morphotypes. The population of both tardigrades and nematodes was composed of mature and juvenile specimens. One tardigrade was collected during their ecdysis process. Our results suggest that not only the nematodes, but also tardigrades and acari can reach the floating Sargassum spp., maintaining in the algae, growing, and reproducing, while they are transported in the sea. We can conclude that in the Caribbean Sea, the floating Sargassum spp. floating is a dispersal mechanism of nematodes and tardigrades.

Tenofovir Disoproxil Fumarate Reduces the Severity of COVID-19 in Patients with Chronic Hepatitis B.

BACKGROUND AND AIMS: HIV-positive patients on tenofovir hydroxyl fumarate (TDF)/emtricitabine have a lower risk of COVID-19 and hospitalization than those given other treatments. Our aim was to analyze the severity of COVID-19 in patients with chronic hepatitis B (CHB) on TDF or entecavir (ETV). METHODS: Spanish hospital databases (n = 28) including information regarding adult CHB patients on TDF or ETV for the period February 1st to November 30th 2020 were searched for COVID-19, defined as a positive SARS-CoV-2 polymerase chain reaction, and for severe COVID-19. RESULTS: Of 4736 patients, 117 had COVID-19 (2.5%), 67 on TDF and 50 on ETV. Compared to patients on TDF, those on ETV showed (p < 0.05) greater rates of obesity, diabetes, ischemic cardiopathy, and hypertension. COVID-19 incidence was similar in both groups (2.3 vs. 2.6%). Compared to TDF, patients on ETV more often (p < 0.01) had severe COVID-19 (36 vs. 6%), required intensive care unit (ICU) (10% vs. 0) or ventilatory support (20 vs. 3%), were hospitalized for longer (10.8 ± 19 vs. 3.1 ± 7 days) or died (10 vs. 1.5%, p = 0.08). In an IPTW propensity score analysis adjusted for age, sex, obesity, comorbidities, and fibrosis stage, TDF was associated with a sixfold reduction in severe COVID-19 risk (adjusted-IPTW-OR 0.17, 95%CI 0.04-0.67, p = 0.01). CONCLUSION: Compared to ETV, TDF seems to play a protective role in CHB patients with SARS-CoV-2 whereby the risk of severe COVID-19 is lowered.

Growth and shell hardness of the apple snail Pomacea flagellata Say, 1829, reared at three calcium concentrations.

The snail Pomacea flagellata inhabits aquatic systems with high calcium concentration and it is important to food webs; unfortunately, its natural populations are decreasing due to overfishing and habitat destruction. Here we tested the effect of three water calcium concentrations on the growth and hardness of snail shells in triplicate recirculation culture systems for 12 weeks. In each culture, 100 juvenile snails were seeded at constant density and fed with balanced tilapia feed. Thirty snails were randomly collected every 15 days and measured in length and total weight. The size, weight, and shell hardness of the snails for the 500 mg/L calcium treatment were significantly higher than the mean size of the snails in the other treatments (300 mg/L and 243.33 mg/L). The calcium supply in the culture promotes growth and allows the snails to produce healthier and stronger shells, in addition to improving their growth rate, which is important for the management of the species.

Estudio de la calidad asistencial prestada en consultas externas a pacientes con cirrosis hepática / No disponible

INTRODUCCIÓN: la calidad de la asistencia prestada a los pacientes cirróticos se puede medir analizando una serie de indicadores. Los estudios publicados hasta la actualidad muestran una tasa de adherencia a las indicaciones de las guías clínicas del 40-80 %. OBJETIVO: valorar la calidad de la asistencia prestada en un hospital docente de tercer nivel. MÉTODOS: estudio observacional retrospectivo en pacientes cirróticos controlados durante un semestre en consultas externas. Se han revisado 324 historias clínicas recogiendo 14 indicadores de calidad de cinco dominios diferentes y se ha estudiado la adherencia global y en relación a la experiencia del médico responsable. RESULTADOS: excelentes (más del 90 % de adherencia) en indicadores relacionados con documentación de la etiología de la cirrosis y profilaxis de la hemorragia digestiva por varices; aceptables (60-90 %) en despistaje del carcinoma hepatocelular y valoración de la gravedad de la enfermedad; y malos (menos del 50 %) en vacunaciones. Los residentes obtuvieron significativamente mejores resultados que los adjuntos en etiología, valoración de la gravedad y dos indicadores de profilaxis de hemorragia digestiva. Por su parte, los adjuntos presentaron mejores resultados en el despistaje de carcinoma hepatocelular. CONCLUSIONES: a pesar de haber obtenido excelentes resultados en algunos indicadores, muchos deben ser mejorados, especialmente las vacunaciones. La calidad asistencial prestada por los residentes es igual o incluso mejor que la prestada por los adjuntos. Analizar la calidad asistencial es esencial para medir y mejorar la atención prestada a los pacientes cirróticos, y puede ser una herramienta muy eficaz para supervisar a los especialistas en formación

No disponible

Quality of care provided to outpatients with hepatic cirrhosis in a teaching hospital.

INTRODUCTION: a set of indicators to measure the quality of care of cirrhotic patients has been established and previously published studies report an adherence rate to clinical guide indications of 40-80 %. OBJECTIVE: to assess the adherence to quality indicators in a tertiary teaching hospital. METHODS: a retrospective observational study was performed of all cirrhotic outpatients seen during one semester in 2017. The charts were studied of 324 patients and quality indicators related to five domains were collected. An overall adherence to 14 quality indicators was recorded and analyzed based on the attending physician's experience. RESULTS: the results were excellent (more than 90 % adherence) for quality indicators related to prophylaxis of variceal bleeding and documentation of cirrhosis etiology, acceptable (60-90 % adherence) for hepatocellular carcinoma screening and disease severity assessment, and poor (less than 50 %) for vaccinations. Residents had significantly better results than experienced physicians in etiology, disease severity assessment and two indicators of prophylaxis of bleeding. Experienced physicians only presented a better adherence to hepatocellular carcinoma screening. CONCLUSIONS: despite excellent results for some quality indicators, most required improvement, especially vaccinations. The quality of care achieved by residents is equal to and even better than that of experienced physicians. Measuring quality of care is essential to analyze and improve the health care of cirrhotic outpatients and may be a useful tool for supervising specialists in training.

Water quality in the eastern karst region of the Yucatan Peninsula: nutrients and stable nitrogen isotopes in turtle grass, Thalassia testudinum.

Water quality in the Mexican Caribbean is affected by increases in tourism infrastructure and poor wastewater treatment. Additionally, karst geomorphology facilitates the infiltration of organic matter to subterranean water and coastal fresh water that originates from submarine groundwater discharges (SGDs), altering the environment. The tourism infrastructure grows at different rates along the Caribbean coast, characterizing zones with diverse levels of tourism impact. The aim of this work was to measure nutrient concentrations in superficial coastal water and fresh water to evaluate the water quality through different zones along a gradient from intermediate- (Riviera Maya) to low-tourism (Costa Maya) development regions. Furthermore, this study aimed to compare the measured nutrient concentrations with the Mexican ecological criteria of water quality 001/89 (CE-CCA-001/89), detect possible contributions by SGDs, and determine whether the nitrogen (N) sources are anthropogenic using stable nitrogen isotopes in the seagrass Thalassia testudinum. According to the results, nutrient concentrations (ammonium, nitrate, nitrite, and orthophosphate) differed significantly between the Riviera Maya and Costa Maya (P = 0.0001). Sites such as Shambala, Chávez, Tankah, Mahahual 2, Tulum, Akumal, and Xahuayxol exceeded the upper levels set by the CE-CCA-001/89. Tankah, Shambala, and Chávez were influenced by SGDs. The nitrogen isotope ratio in Akumal and Tulum coast water shows that they are under N loading derived to the sewage percentage of δ15N in Akumal, Tulum, and Mahahual, showing that these sites suffer N loading due to sewage. Our study recommends continuous monitoring and coastal characterization to detect SGD and to regulate, treat, and dispose of sewage.

Erratum: Author Correction: Biodiversity estimates and ecological interpretations of meiofaunal communities are biased by the taxonomic approach.

[This corrects the article DOI: 10.1038/s42003-018-0119-2.].

Biodiversity estimates and ecological interpretations of meiofaunal communities are biased by the taxonomic approach.

Accurate assessments of biodiversity are crucial to advising ecosystem-monitoring programs and understanding ecosystem function. Nevertheless, a standard operating procedure to assess biodiversity accurately and consistently has not been established. This is especially true for meiofauna, a diverse community (>20 phyla) of small benthic invertebrates that have fundamental ecological roles. Recent studies show that metabarcoding is a cost-effective and time-effective method to estimate meiofauna biodiversity, in contrast to morphological-based taxonomy. Here, we compare biodiversity assessments of a diverse meiofaunal community derived by applying multiple taxonomic methods based on comparative morphology, molecular phylogenetic analysis, DNA barcoding of individual specimens, and metabarcoding of environmental DNA. We show that biodiversity estimates are strongly biased across taxonomic methods and phyla. Such biases affect understanding of community structures and ecological interpretations. This study supports the urgency of improving aspects of environmental high-throughput sequencing and the value of taxonomists in correctly understanding biodiversity estimates.

Reproducción de Pomacea flagellata (Mollusca: Ampullariidae) en la laguna de Bacalar, Quintana Roo, México / Reproductive aspects of Pomacea flagellata (Mollusca: Ampullariidae) at Bacalar lagoon, Quintana Roo, México

Resumen:Pomacea flagellata es una especie de caracol de agua dulce nativo en el sureste de México. Sobre esta especie existen pocos estudios y en ninguno se han abordado aspectos de su reproducción. Este caracol ha sido explotado durante años en la laguna Bacalar y sus poblaciones han decrecido considerablemente, conllevando a la veda de su captura. Este trabajo se realizó con el objetivo de evaluar las variaciones temporales de la frecuencia de cópulas y la abundancia de masas de huevos de P. flagellata en la laguna de Bacalar, así como sus relaciones con la abundancia de los caracoles y con variables ambientales. Los muestreos fueron realizados durante tres temporadas: Lluvias (julio, agosto y septiembre 2012), Nortes (diciembre 2012, enero y febrero 2013) y Secas (marzo, abril y mayo 2013) en 12 estaciones a lo largo de la laguna de Bacalar. En cada estación, se recorrió un transecto de 100 m paralelo a la orilla y se contó el número de huevas frescas (color rosado) puestas sobre la vegetación, troncos, rocas o estructuras artificiales. En el agua se hicieron tres transectos de 50 x 2 m y en cada uno se contaron los caracoles y se registró el número de cópulas. La densidad de caracoles mostró variaciones significativas entre temporadas, disminuyendo desde la temporada de Lluvias hasta la temporada de Secas. Entre los meses dentro de temporadas no se presentaron diferencias significativas (ANOVA, p>0.05). Durante toda la temporada de Lluvias se registraron cópulas con una frecuencia significativamente mayor que en Nortes, mientras en Secas no se registraron cópulas (Kruskal-Wallis, p˂0.05). La puesta de masas de huevos se extendió de julio a marzo. La densidad de huevas no presentó diferencias entre la temporadas de Lluvias y Nortes (2.72 masas/m y 2.93 masas/m, respectivamente), pero en Secas fue significativamente menor con un valor de 0.1 masas/m (H, p˂0.05). La frecuencia de cópulas se relacionó significativamente con la abundancia de caracoles (rs= 0.26; p<0.05) y con la temperatura del agua (rs= 0.34; p<0.05). La abundancia de masas de huevos se relaciona significativamente con la abundancia de individuos (rs= 0.46; p<0.05). De forma general se observó que la actividad reproductiva de P. flagellata en la laguna de Bacalar, está asociada a los meses más cálidos y con mayor precipitación. Este hallazgo es relevante para apoyar la gestión de este recurso en la región, de tal forma que para implementar alguna medida de manejo para esta especie, es necesario tener en cuenta que al menos se debe mantener una veda temporal durante la etapa reproductiva.

Abstract:The freshwater snail Pomacea flagellata is native from Southeastern Mexico. Studies about this species are scarce and none has treated their reproduction. This snail has been exploited at Bacalar lagoon for many years, leading to a significant decrease in their abundance and currently, a permanent ban was proposed by the government. This work aimed to assess the temporal variations of mating frequency and the abundance of egg clutches of P. flagellata at Bacalar lagoon, as well as their relation with snails density and environmental variables. Sampling was done during the three climatic seasons: Rainy (July, August and September/2012), North or Cold fronts (December/2012 and January and February/2013) and Dry (March, April and May/2013) in 12 sampling stations located along the Bacalar lagoon. On each station a transect of 100 m length was set parallel to the edge, and the number of fresh egg clutches (pink color) laid over vegetation, rocks or manmade structures, were counted. In the water, three 50 x 2 m transects were set and the number of snails were counted as well as the mating frequency. Density of snails varied significantly among seasons, decreasing from the rainy to the dry season. There were no significant differences of snail abundance among months, nested in climatic seasons (ANOVA, p>0.05). During the rainy season the mating frequency was significantly higher than in the Norths, meanwhile in the dry season no mating were registered (Kruskal-Wallis, p˂0.05). Eggs clutches appeared from July to March. Density of egg clutches presented no differences between the Rainy and the North seasons (2.72 and 2.93 clutches/m, respectively), nonetheless during the dry season abundance of egg masses was significantly lower (0.1 clutches/m) (H, p˂0.05). Mating frequency was related with snail abundance (rs= 0.26; p<0.05) and water temperature (rs= 0.34; p<0.05) and the abundance of egg masses is related with snail abundance (rs= 0.46; p<0.05). In general, we observed that reproductive activity of P. flagellata at Bacalar lagoon is related with the warmer months and with higher rainfall. This finding is relevant to support the management of this resource in the region, so that to implement any management arrangement they must be aware that a temporal ban is necessary during the reproductive season at least. Rev. Biol. Trop. 64 (4): 1643-1650. Epub 2016 December 01.

Efectos del disturbio humano sobre la dinámica poblacional de Ocypode quadrata (Decapoda: Ocypodidae) en playas del Caribe mexicano / Effects of human disturbance on the population dynamics of Ocypode quadrata (Decapoda: Ocypodidae) in beaches of the Mexican Caribbean

Resumen:El cangrejo fantasma Ocypode quadrata, tiene una alta relevancia ecológica en las playas del Atlántico occidental y se ha propuesto como un indicador del impacto humano sobre este ecosistema. Sin embargo, no se han evaluado los efectos del disturbio humano sobre su dinámica poblacional. En este trabajo se compara la abundancia, el crecimiento y la mortalidad de O. quadrata en dos playas perturbadas (Aventuras y Majahual) y dos playas conservadas (Xcacel y Puerto Ángel) de las costas del Caribe mexicano. Se realizaron nueve muestreos en cada playa (marzo/2013-noviembre/2014). Durante las primeras horas de la noche se recolectaron cangrejos, de forma manual por tres personas, en un área aproximada de 9 000 m2. Los cangrejos fueron medidos, pesados y separados en tres grupos: jóvenes, hembras y machos. La mayor abundancia de cangrejos se encontró en las playas conservadas pero solo se observaron diferencias significativas entre Puerto Ángel y Majahual (Tukey, p<0.05). La proporción jóvenes- adultos fue 1:1 en Xcacel y Aventuras. En Majahual se recolectó un mayor número de jóvenes que adultos y en Puerto Ángel el número de adultos triplicó el de jóvenes. La talla máxima para Aventuras, Xcacel, Majahual y Puerto Ángel fue de 27, 32, 25 y 30 mm, respectivamente. En las playas se encontraron entre dos y tres grupos de edades diferentes. En las cuatro playas se recolectaron individuos con tallas menores de 10 mm en casi todos los meses de muestreo, indicando que el reclutamiento es continuo durante todo el año. La relación entre la longitud y el peso del cangrejo fantasma fue isométrica en las playas mejor conservadas y alométrica negativa en las playas impactadas. Los cangrejos de Puerto Ángel mostraron mejor condición corporal que en el resto de las playas (Tukey, p<0.05). Los valores de K oscilaron entre 0.6-0.97/año y la L∞ entre 29.0-33.6 mm. Los cangrejos en las dos playas conservadas mostraron mayores parámetros de crecimiento en comparación con las dos playas perturbadas. Los mayores valores de mortalidad se encontraron en Xcacel y Aventuras. En las playas perturbadas, la destrucción de las dunas, la limpieza mecánica y la remoción de materia orgánica, parecen ser las principales causas que conllevan a una baja abundancia de cangrejos, un menor crecimiento y una alta mortalidad. Sin embargo en las playas mejor conservadas, las relaciones biológicas parecen ser más importantes en regular la dinámica poblacional de esta especie. Estos resultados tienen relevancia desde el punto de vista de manejo de las playas arenosas, ya que el cangrejo fantasma es un buen indicador del disturbio humano y sus respuestas poblacionales son medibles y comparables.

Abstract:The ghost crab Ocypode quadrata is a relevant species in the Western Atlantic beaches, and has been proposed as an indicator of human impact in these ecosystems. Eventhough some studies have covered various aspects of its natural history, no evaluations on the effects of human disturbance on its population dynamics have been made. This work compared the abundance, growth, and mortality of O. quadrata in two disturbed beaches (Aventuras and Majahual) and two preserved beaches (Xcacel and Puerto Angel) from the Mexican Caribbean. For this, nine samplings were made on each beach (every two to three months) between March 2013 and November 2014. Crabs were collected manually by three people, during the night first hours and for one hour, and a total area of 9 000 m2 per beach. The crabs were measured, weighed, and separated into three groups: juvenile, male and female; while abundance was estimated by the number of collected crabs, and growth parameters were estimated using length frequencies. A total of 1 047 crabs were sampled in the four beaches; a higher crab abundance was found in the preserved beaches, but significant differences were only found between Puerto Angel and Majahual (Tukey, p<0.05). The adult- juvenile ratio was 1:1 in Xcacel and Aventuras, while in Majahual, more juveniles than adults were collected; and Puerto Angel had more adults than the juveniles. The size structure at Xcacel ranged from 4-32 mm, but in the rest of the beaches the minimum size was 5 mm. The maximum size at Aventuras, Majahual and Puerto Angel were 27 mm, 25 mm and 30 mm, respectively. The modal progression analysis of length's pooled data, revealed the presence of at least two groups of ages in all beaches. For all beaches, individuals smaller than 10 mm length were collected in almost all sampling months, indicating a continuous recruitment throughout the year. The length-weight relationship of the ghost crab was found isometric in the two preserved beaches, and negative allometric at the two impacted beaches. Crabs from Puerto Angel showed the highest body condition (Tukey, p<0.05). K-values ranged from 0.6-0.97/year and L∞ from 29.0 mm to 33.6 mm with higher values for the two preserved beaches. The highest mortality values were found in Xcacel and Aventuras. In the disturbed beaches, the destruction of the dunes, the mechanical cleaning and the removal of organic matter, seem to be the main causes that lead to a low abundance of crabs, their slower growth and higher mortalities. However, in the best preserved beaches, biological interactions appear to be the most important aspects in regulating the population dynamics of this species. These results supported the information that the ghost crab is a good indicator of human disturbance, and its population changes were clearly measurable and comparable among protected and impacted beaches; these results are also relevant for the management of sandy beaches in the Mexican Caribbean. Rev. Biol. Trop. 64 (4): 1625-1641. Epub 2016 December 01.

Caracterización de la ovoposición del caracol Pomacea flagellata (Say, 1827) bajo condiciones experimentales / Characterization of oviposition snail Pomacea flagellata (Say, 1827) under experimental conditions

Pomacea flagellata es un caracol conspicuo de zonas tropicales y subtropicales de América, que se ha consumido desde tiempos prehispánicos y actualmente es considerado sobreexplotado. Se realizó un experimento de cultivo de cuatro meses para determinar: la selección del substrato por la hembra, el tamaño de las huevas, el nivel del agua elegido para colocar la masa de huevos, el número de crías, y el tiempo de eclosión. Se utilizaron tres tinas de plástico que se llenaron con 100 L de agua, por duplicado y se colocaron tres sustratos: raíces de mangle, carrizo y tubo de PVC. Se registraron 57 huevas, 26 de ellas eclosionaron produciendo 5037 crías. Hubo más huevas en la "pared" de las tinas, donde se registraron 35 huevas, en raíces de mangle (18), en PVC 3 y en carrizo una hueva. Hubo diferencias significativas en la selección del sustrato, mientras que no se observaron diferencias significativas entre el número de huevas y las proporciones de sexos. La longitud promedio de la masa fue 32.99 ± 10.92, el ancho 16.44 ± 5.1 y grosor 8.08 ± 3.87 mm. La altura promedio de la puesta fue 15.66 ± 3.42 cm, con un tiempo medio de eclosión, de 13.30 ± 2.6 días, obteniéndose entre 94 a 301 crías por desove. Los caracoles utilizaron preferentemente las paredes de las tinas y es difícil determinar si no seleccionan sustrato para la puesta. El nivel del agua empleado es óptimo y permite que los organismos puedan colocar las masas de huevo, la producción de crías es adecuada y suficiente para iniciar programas de cultivo de producción de carne o de repoblación del medio natural.

Pomacea flagellata is a conspicuous snail in tropical and subtropical areas of America; it has been consumed since pre-Hispanic times and now is considered overexploited. A four months cultivation experiment was realized to determine the substrate selection by females, size of clutches, water level for placing egg masses, number of offspring, and hatching time. We used three duplicate plastic vats that were filled with 100 L water, and three substrates were set inside: mangrove roots, reed and PVC pipes. A total of 57 eggs masses were recorder, 26 of them produced 5037 offspring. More eggs masses were set in the wall of vats (35), mangrove roots (18) PVC pipe 3 and reed only one. There were significant differences in the selection of the substrate, but not between the number of eggs masses and sex proportion. Average length of egg masses was 32.99 ± 10.92, width was 16.44 ± 5.1 and thickness 8.08 ± 3.87 mm. Average heights of the egg masses was 15.66 ± 3.42 cm, while hatching time was 13.30 ± 2.6 days, yielding between 94 to 301 offspring per spawning. Snails preferably used walls of vats and it is difficult to determine if they did not select a substrate. Water level in the vats was optimal and allowed to organisms place egg masses, offspring production is adequate and enough to start culturing programs to meat production, or to re stocking of natural environment.

[Effects of human disturbance on the population dynamics of Ocypode quadrata (Decapoda: Ocypodidae) in beaches of the Mexican Caribbean]. / Efectos del disturbio humano sobre la dinámica poblacional de Ocypode quadrata (Decapoda: Ocypodidae) en playas del Caribe mexicano.

The ghost crab Ocypode quadrata is a relevant species in the Western Atlantic beaches, and has been proposed as an indicator of human impact in these ecosystems. Eventhough some studies have covered various aspects of its natural history, no evaluations on the effects of human disturbance on its population dynamics have been made. This work compared the abundance, growth, and mortality of O. quadrata in two disturbed beaches (Aventuras and Majahual) and two preserved beaches (Xcacel and Puerto Angel) from the Mexican Caribbean. For this, nine samplings were made on each beach (every two to three months) between March 2013 and November 2014. Crabs were collected manually by three people, during the night first hours and for one hour, and a total area of 9 000 m2 per beach. The crabs were measured, weighed, and separated into three groups: juvenile, male and female; while abundance was estimated by the number of collected crabs, and growth parameters were estimated using length frequencies. A total of 1 047 crabs were sampled in the four beaches; a higher crab abundance was found in the preserved beaches, but significant differences were only found between Puerto Angel and Majahual (Tukey, p<0.05). The adult-juvenile ratio was 1:1 in Xcacel and Aventuras, while in Majahual, more juveniles than adults were collected; and Puerto Angel had more adults than the juveniles. The size structure at Xcacel ranged from 4-32 mm, but in the rest of the beaches the minimum size was 5 mm. The maximum size at Aventuras, Majahual and Puerto Angel were 27 mm, 25 mm and 30 mm, respectively. The modal progression analysis of length's pooled data, revealed the presence of at least two groups of ages in all beaches. For all beaches, individuals smaller than 10 mm length were collected in almost all sampling months, indicating a continuous recruitment throughout the year. The length-weight relationship of the ghost crab was found isometric in the two preserved beaches, and negative allometric at the two impacted beaches. Crabs from Puerto Angel showed the highest body condition (Tukey, p<0.05). K-values ranged from 0.6-0.97/year and L∞ from 29.0 mm to 33.6 mm with higher values for the two preserved beaches. The highest mortality values were found in Xcacel and Aventuras. In the disturbed beaches, the destruction of the dunes, the mechanical cleaning and the removal of organic matter, seem to be the main causes that lead to a low abundance of crabs, their slower growth and higher mortalities. However, in the best preserved beaches, biological interactions appear to be the most important aspects in regulating the population dynamics of this species. These results supported the information that the ghost crab is a good indicator of human disturbance, and its population changes were clearly measurable and comparable among protected and impacted beaches; these results are also relevant for the management of sandy beaches in the Mexican Caribbean.

[Reproductive aspects of Pomacea flagellata (Mollusca: Ampullariidae) at Bacalar lagoon, Quintana Roo, México]. / Reproducción de Pomacea flagellate (Mollusca: Ampullariidae) en la laguna de Bacalar, Quintana Roo, México.

The freshwater snail Pomacea flagellata is native from Southeastern Mexico. Studies about this species are scarce and none has treated their reproduction. This snail has been exploited at Bacalar lagoon for many years, leading to a significant decrease in their abundance and currently, a permanent ban was proposed by the government. This work aimed to assess the temporal variations of mating frequency and the abundance of egg clutches of P. flagellata at Bacalar lagoon, as well as their relation with snails density and environmental variables. Sampling was done during the three climatic seasons: Rainy (July, August and September/2012), North or Cold fronts (December/2012 and January and February/2013) and Dry (March, April and May/2013) in 12 sampling stations located along the Bacalar lagoon. On each station a transect of 100 m length was set parallel to the edge, and the number of fresh egg clutches (pink color) laid over vegetation, rocks or manmade structures, were counted. In the water, three 50 x 2 m transects were set and the number of snails were counted as well as the mating frequency. Density of snails varied significantly among seasons, decreasing from the rainy to the dry season. There were no significant differences of snail abundance among months, nested in climatic seasons (ANOVA, p>0.05). During the rainy season the mating frequency was significantly higher than in the Norths, meanwhile in the dry season no mating were registered (Kruskal-Wallis, p˂0.05). Eggs clutches appeared from July to March. Density of egg clutches presented no differences between the Rainy and the North seasons (2.72 and 2.93 clutches/m, respectively), nonetheless during the dry season abundance of egg masses was significantly lower (0.1 clutches/m) (H, p˂0.05). Mating frequency was related with snail abundance (rs= 0.26; p<0.05) and water temperature (rs= 0.34; p<0.05) and the abundance of egg masses is related with snail abundance (rs= 0.46; p<0.05). In general, we observed that reproductive activity of P. flagellata at Bacalar lagoon is related with the warmer months and with higher rainfall. This finding is relevant to support the management of this resource in the region, so that to implement any management arrangement they must be aware that a temporal ban is necessary during the reproductive season at least.

[Size structure as evidence of population establishment of Pterois volitans (Scorpaeniformes: Scorpaenidae) in the South Mexican Caribbean]. / La estructura de tallas como evidencia del establecimiento de Pterois volitans (Scorpaeniformes: Scorpaenidae) en el sur del Caribe mexicano.

The lionfish (P. volitans) has now invaded all the Mexican Caribbean and Gulf of Mexico, with the potential to cause negative impacts on the reefs. In the South Mexican Caribbean was firstly reported in July 2009, and six years after this report, some control measures such as fish tournament and local marketing have been implemented. However, information on its biology and invasion is still-lacking, so this study analyzed the population structure of 2 164 organisms collected from 2009 to 2012. An increase was observed in sizes for each year averaging Total length (Tl): 118 ± 34.8, 133 ± 56.3, 187 ± 74.8 and 219 ± 72.4 mm, respectively. Lionfish establishment at the study site is shown for the presence of juveniles' sizes 20 mm TL up to 375 mm TL. When the back-calculation was obtained, we estimated that the larger fish could have recruited in early 2006, three years before the first report was made. A continuous population monitoring and an ecological study, will allow us to clarify the real impact in the ecosystems of the region and so to propose the most effective control actions.

Rhynchonema dighaensis sp. nov. (Monhysterida: Xyalidae): a marine nematode from the Indian coast with an illustrated guide and modified key for species of Rhynchonema Cobb, 1920.

A small bodied, free-living marine nematode, Rhynchonema dighaensis sp. nov., is described from the intertidal sand of the east coast of India. It is characterized by having a small buccal cavity, longer left spicule and symmetrical dorsal gubernaculum apophysis. Other species of the genus are discussed with their type locality. A modified key has been prepared for species of Rhynchonema with an illustrated guide. Species of Rhynchonema primarily differ from each other by the shape and size of the spicules, shape of the gubernaculum and dorsal apophysis, size of the buccal cavity and position of the amphid. 

Densidad, estructura de tallas y actividad reproductiva del caracol rosado Eustrombus gigas (Mesogastropoda: Strombidae) en Banco Chinchorro, México / Density, size structure and reproductive activity of the pink conch Eustrombus gigas (Mesogastropoda: Strombidae) in Banco Chinchorro, Mexico

The pink conch Eustrombus gigas is an important fisheries resource. At the regional level in the Caribbean, over-exploitation and habitat destruction have caused a decrease in the abundance of this resource. In order to provide necessary information for the species management in Mexico, this work aimed to analyze the total density, adult density, size structure and reproductive behavior of pink conch population at Banco Chinchorro during 2009-2010. Data from three seasons were obtained (rainy, dry and cold fronts periods) in three areas: Norte (North), Centro (Center) and Sur (South). The organisms were separated into two groups: (a) the criteria based upon legal harvest in Mexico: legal size conchs (siphonal length≥200mm) and illegal size conchs (siphonal length<200mm), and (b) the criteria based upon sexual maturity using the 15mm lip thickness standard: lip<15mm as juvenile conch and lip≥15mm as adult conch. Copulation, spawning, egg masses and aggregations were evaluated as reproductive evidences. The highest total density was observed during the dry season with 384ind./ha, and the lowest during the rainy season with 127ind./ha. The highest density was reported at Sur (385ind./ha) and the lowest at Norte (198ind./ha). The highest adult density was observed during the rainy season (8.33ind./ha), and the lowest occurred in the dry season (6.11ind./ha). Adult density values were 5.55, 7.05 and 8.33ind./ha for Centro, Sur and Norte areas, respectively. Adult densities were lower than the threshold needed for reproduction, and 42% of the population may be vulnerable to fishing, as they had the minimum size for catch (Lsi 200mm). Furthermore, only 2.2% of the population reached a Gl>15mm as sexual maturity indicator. During the study period, only six evidences of reproductive activity were observed. The smaller densities reported at Banco Chinchorro may cause reproduction events to be almost absent which in turn is sufficient ...

Eustrombus gigas es uno de los recursos pesqueros costeros más valiosos en la región del Caribe y constituye un molusco con un elevado valor estético y ecológico. En esta investigación se evalúa su densidad total, densidad de adultos, la estructura de tallas y frecuencia de evidencias reproductivas en Banco Chinchorro, México, periodo 2009-2010; durante tres períodos (de lluvias, seca y de frentes fríos) en tres zonas: Norte, Centro y Sur. La densidad total para el área de estudio varió de 127ind./ha en lluvias a 384ind./ha en seca, la menor densidad se presentó en la zona Norte del Banco (198ind./ha) y la mayor en la zona Sur (385ind./ha). La densidad de caracoles adultos fue baja (6.11ind./ha en seca y 8.33ind./ha en lluvias y 5.55, 7.05 y 8.33ind./ha para las zonas Centro, Sur y Norte, respectivamente). Las densidades de adultos estuvieron por debajo del umbral mínimo necesario para mantener la reproducción. El 42% de la población es vulnerable a la pesca (Lsi≥200mm); sin embargo, solo 2.2% de la población alcanza un Gl>15mm. Solo se observaron seis evidencias de reproducción durante el período de estudio, lo que señala la presencia del efecto Allee en la población y la urgente necesidad del cierre de su pesquería. Se proponen tres puntos importantes para el manejo de la especie: cierre de la pesca, monitoreo de la población y la implementación refugios pesqueros.

Declining densities and reproductive activities of the queen conch Strombus gigas (Mesogastropoda: Strombidae) in Banco Chinchorro, Eastern Caribbean, Mexico / Disminución de la densidad y actividades reproductivas de la concha reina Strombus gigas (Mesogastropoda: Strombidae) en el Banco Chinchorro, Caribe Oriental

Queen conch is a gastropod inhabiting the Caribbean Sea, it represents the second largest fishery after the spiny lobster, but it has been extensively captured in the area. In order to know its population status in Chinchorro Bank, we determined conch density changes and its effects on reproductive activities, between July and November 2009. For this, data on conch density, morphology and reproductive activities were obtained from 15 sites within three fishing zones, and compared with previously collected data (1990, 1992, 1994, and 1997). Data showed that adult density decreased with time, from 10 700ind./ha in 1990, to 198ind./h in 2009. Neither egg masses nor spawns were found and mating was only observed once in July 2009. In July, adult (lip>4mm) density in the Southern zone was 23ind./ha whereas in the Northern zone and Central zone densities were 15 and 9ind./ha respectively. In November, density was somewhat higher: Southern zone 96ind./ha; Central zone 39ind./ha and Northern zone had 38ind./ha. In July, mean shell length was 170.80±46.28mm, with a higher median abundance at 180-189mm. In November, higher frequency was 187.63±45.14mm, maximum at 210-219mm interval. For the last 10 years period, mean adult conch densities have diminished in each zone, which might be the main cause of decreased reproductive activities of the conch at Banco Chinchorro. It is therefore an immediate need to analyse the management plan for this species in this Reserve and perhaps to promote a re-population of queen conch and culture activities. Rev. Biol. Trop. 61 (4): 1671-1679. Epub 2013 December 01.

El caracol Rosado es un gasterópodo que habita en el Caribe, y representa la segunda pesquería después de la langosta espinosa, sin embargo, el caracol ha sido pescado a niveles de casi extinción. Para conocer el estatus de la población se analizaron los cambios de densidad del caracol rosado en Banco Chinchorro y su efecto en las actividades reproductivas entre julio y noviembre 2009. Se recolectaron datos de densidad y morfología en tres zonas de pesca en 15 localidades; y se compararon con datos recolectados previamente en los mismos sitios (1990, 1992, 1994, y 1997). Los datos mostraron que la densidad de adultos ha decrecido con el tiempo de 10 700 (ind./ha) en 1990 a 198 (ind./ha). Las actividades reproductivas o productos se registraron, no se encontraron ni masas de huevo ni desoves, y únicamente se observó una copulación en julio. Considerando únicamente a los adultos (labio>4mm), en julio 2009, la densidad fue de 23ind./ha, mientras que en la zona norte y centro las densidades fueron 15 and 9 (ind./ha). En noviembre 2009, la densidad fue ligeramente más alta: zona sur 96 (ind./ha); zona Centro 39 (ind./ha) y zona Norte 38 (ind./ha). En julio (2009) la longitud de concha promedio fue de 170.80±46.28mm, con una mayor abundancia en las tallas 180-189mm. En noviembre (2009) la frecuencia más alta ocurrió en las talla promedio 187.63±45.14mm, con un intervalo de 210-219mm de longitud de concha. En los últimos 10 años, la densidad de los caracoles adultos ha disminuido en cada una de las zonas de pesca, lo cual podría ser la causa de la disminución de las actividades reproductivas del caracol rosado en Banco Chinchorro.