Ictioplancton del sur del Golfo de México. Un compendio.

The Zooplankton laboratory of the Instituto de Ciencias del Mar y Limnología, UNAM, had studied for about 25 years the ichthyoplankton from the southern Gulf of Mexico. The objectives have been to determine which species exist, where are they distributed, their abundance, which communities form, how do they vary and why. It has been recorded the presence of at least 306 species, distributed on 283 genus and 120 families of fish larvae. Diversity and abundance appear as opposite parameters, the higher abundance occurs in coastal areas and mid shelf, diminishing towards oceanic zone. In contrast the diversity is higher in oceanic areas, continental edge and decreases in coastal areas. This distribution shows a recurrent pattern. In general, the distribution and abundance of larvae are determined by the spawning area and season of the adults, food availability, and physical process, mainly currents, continental water discharges, and mixing processes. The vertical distribution of larvae in the water column probably depends on the habitat of adults. Larvae of coastal dwelling adults, tend to occupy mainly the 30 m surface layer, whereas larvae of oceanic parents, generally occupy layers deeper than 50 m. All larvae tend to be more dispersed at night. It has been determined four recurrent communities: a) Coastal, b) Internal Neritic, c) External Neritic and d) Oceanic.El laboratorio de Zooplancton del Instituto de Ciencias del Mar y Limnología de la UNAM, ha estudiado por más de 25 años el ictioplancton del sur del Golfo de México. Los objetivos han sido determinar qué especies existen, dónde se distribuyen, cuál es su abundancia, qué comunidades forman, cuál es y a qué se debe su variación espacio-temporal. Se ha registrado la presencia de al menos 306 especies, 283 géneros y 120 familias de larvas de peces. La diversidad de especies y la abundancia de larvas aparecen como parámetros opuestos; la mayor densidad de organismos ocurre en áreas costeras y en plataforma media y disminuye hacia la zona oceánica; la diversidad en cambio es mayor en áreas oceánicas, al borde de la plataforma continental y se reduce hacia estaciones costeras. En general, la distribución de la abundancia de las larvas tiene un patrón recurrente y está determinada por las áreas y épocas de desove de las especies, por la disponibilidad de alimento y los procesos físicos, principalmente corrientes, descargas de agua continental y mezcla. La distribución de las larvas en la columna de agua parece depender del hábitat de sus adultos, aquellas cuyos adultos viven la zona costera se encuentran primordialmente en los primeros 30 m; las de origen oceánico ocupan generalmente capas con profundidades mayores a 50 m. Todas tienden a una mayor dispersión en la columna durante la noche. Se ha determinado la presencia recurrente de cuatro comunidades: a) Costera, b) Nerítica Interna, c) Nerítica Externa y d) Oceánica

Seasonal vertical distribution of fish larvae in the southern Gulf of Mexico

Changes in the composition and abundance of fish larvae in the water column were analyzed throughout an annual cycle (1994-1995) in the southern Gulf of Mexico, in order to establish the difference between the habitat of the larvae and the effect of oceanographic events on larval vertical distribution. The study area comprised the continental shelf off Tabasco and Campeche in the southern Gulf of Mexico. Samples were collected at five water column levels: 0-6, 6-12, 12-18, 45-55 and 95-105 m. A total of 118 taxa were identified, 52 were dominant species, 33 were larvae of neritic parents and 19 were larvae of mesopelagic parents. The results indicate that the water column presented two layers above the 105 m depth: a surface layer (0-18 m) and a deep layer (45-105 m). The greatest density of larval species that inhabit neritic areas as adults was recorded in the surface layer (0-18 m), while larvae of which the parents inhabit mesopelagic areas were found in the deep layer (45-105 m). The mixing of the water column was the most important physical factor regarding the variation in the vertical distribution of the larvae of both groups, particularly in winter. However, the biology of each species and the habit to occupy a particular depth was the most important factor that determined their distribution in the water column

Mapping and Estimation of Nitrogen and Sulfur Atmospheric Deposition Fluxes in Central Region of the Mexican Bajio

The objective of this study was to assess the spatial and temporal distribution of nitrogen and sulfur deposition and its relationship with meteorological conditions in the metropolitan area of León in Guanajuato, México. N and S atmospheric deposition was collected using passive samplers (IER) in 10 sites in León City during three climatic seasons in 2018. Nitrate, ammonium, and sulfate concentrations and deposition fluxes of N and S were determined. From wind and air-mass trajectories analysis, mechanisms and possible sources contributing to N and S deposition in the study area were assessed. Atmospheric deposition fluxes were compared to critical load values reported for sensitive ecosystems in Europe. It was found that mean deposition flux for N (5.82 Kg N ha−1 year−1) was within the range of values reported for sensitive ecosystems in Nuevo México, Europe, and California. On the other hand, the mean deposition flux for S (13.77 S Kg ha−1 year−1) exceeded the critical load values proposed for Europe, suggesting that current S deposition could be a risk for ecosystems and water bodies in the region

Characterization and Sources of Aromatic Hydrocarbons (BTEX) in the Atmosphere of Two Urban Sites Located in Yucatan Peninsula in Mexico

Abstract:Benzene,toluene,ethylbenzene,p-xylene,O3,NOx,CO,PM2.5 andmeteorologicalparameters were measured in urban air of two sites in Merida, Yucatan, Mexico during 2016–2017. Samples were collected using 1.5 h time intervals at three different sampling periods before being analyzed by gas chromatographywithflameionizationdetection. ThehighestconcentrationsofBTEXoccurredduring midday and afternoon in spring and summer seasons. Mean concentrations of, BTEX for the Cholul and SEDUMA sites, respectively, were 40.91 µg/m3 and 32.86 µg/m3 for benzene; 6.87 µg/m3 and 3.29 µg/m3 for toluene; 13.87 µg/m3 and 8.29 µg/m3 for p-xylene; and 6.23 µg/m3 and 4.48 µg/m3 for ethylbenzene. The toluene/benzene and xylene/ethylbenzene concentration ratios indicated that BTEX levels at both sites were influenced by local and fresh emissions (vehicular traffic). Bivariate and multivariate analyses were performed in order to correlate BTEX concentrations with criteria air pollutants to infer their possible sources. Health risk assessment revealed that exposure to benzene exceeded the recommended value for the integrated lifetime cancer risk. These results suggest that Merida’s population is exposed to cancer risk, and changes in the existing environmental policies should therefore be applied to improve air quality. Keywords: volatile organic compounds; BTEX; tropospheric ozone; Merida; air pollutio

Short-term Effects of Air Pollution on Health in the Metropolitan Area of Guadalajara using a Time-series Approach

ABSTRACT This work have like purpose quantitative estimates of the short-term effects of air pollution on the health of residents of five municipalities of the Metropolitan Area of Guadalajara, Mexico from 2012 to 2015 using time-series approach. Air Quality was assessed for CO, NO2, SO2, O3 and PM10. Tlaquepaque had the highest mean concentrations for CO (0.88 ppm), NO2 (24.55 ppb), SO2 (0.0036 ppm) and PM10 (53.81 µg m–3), whereas, Zapopan registered the highest mean value for O3 (25.06 ppb). Only PM10 and Ozone exceeded the maximum permissible values established in the Mexican official standards. SO2 presented the highest RRI values in MAG, especially for Zapopan and Tonala, for the majority of the population: 0–59 years and > 60 years. Regarding to CO, excepting Guadalajara and Tlaquepaque, associations were not significant in the most of studied municipalities. The increase of risk as percentage for NO2 was 1.77% for 0–59 years in Guadalajara and Tlaquepaque, 1.87% by respiratory causes in Tlaquepaque, 1.73% > 60 years in Tonala, and 1.25% for 0–59 years in Zapopan. The association between daily mortality and increased O3 levels were significant, however, values were low for all studied municipalities. Finally, regarding to PM10, only Zapopan and Tonala showed statistical significance. This study cannot predict if reductions in criteria pollutants levels would have an important effect on a reduction in daily mortality, however, considering the large size of population exposed, even when observed associations were small but significant, RRI values found are of public concern. Keywords: Relative risk index; Mortality; Megacities; Criteria air pollutants; Mexico

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Relationship between zooplankton biomass and continental water discharges in the southern Gulf of Mexico (1984-2001)

Zooplankton biomass is recognized as an important indicator of secondary production, its spatial and temporal variation in neritic zones is particularly affected by discharges of the rivers, and the spatial-temporal effect of continental water discharges on the distribution of zooplankton biomass in the southern Gulf of Mexico was analyzed for 5 areas off the coasts of Veracruz, Tabasco and Campeche. The analyzed material was obtained from 534 samples collected during different climatic seasons from 1984 to 2001. The discharge volumes of 5 hydrological regions were obtained from the government's data base. The results obtained indicated that biomass variation throughout the seasons in the different areas was very similar to the pattern of discharges. The greater biomass values were recorded off Tabasco and the lower values off Veracruz, where the greater and lower continental water discharges were recorded respectively. Biomass variation depended on the discharges, not only in terms of an annual cycle, but was also directly related to the volumes discharged into the ocean. A Tree analysis made it possible to conclude that biomass is always low on the outer shelf and oceanic region of the southern Gulf of Mexico, independently of the season of the year or of a particular area. A greater biomass was recorded on the shallow shelf, with a magnitude that varied in relation to the area and season. The biomass off Campeche did not depend on the continental water discharges, but was generated on the Yucatán shelf.La biomasa zooplanctónica es reconocida como un importante indicador de la producción secundaria; su variación espacio-temporal en zonas neríticas es afectada particularmente por las descargas de los ríos, por lo que se analiza el efecto espacio temporal de las descargas de aguas continentales en la distribución de la biomasa zooplanctónica en el sur del Golfo de México, en 5 áreas frente a las costas de Veracruz, Tabasco y Campeche. El material analizado proviene de 534 muestras recolectadas en diferentes estaciones climáticas entre 1984 y 2001. Los volúmenes de descargas de 5 regiones hidrológicas se obtuvieron de la base de datos gubernamentales. Los resultados muestran que las variaciones de la biomasa durante las estaciones del año en las diferentes áreas son muy similares al patrón de las descargas. Los mayores valores de biomasa ocurren enfrente de las costas de Tabasco y los menores frente a Veracruz, donde se tienen las mayores y menores descargas de aguas continentales respectivamente. La variación de la biomasa depende de las descargas, no sólo en términos de un ciclo anual, sino también directamente relacionada con el tamaño del volumen vertido al océano. El análisis de árbol permitió concluir que en el sur del Golfo de México sobre la parte externa de la plataforma y zona oceánica, la biomasa siempre es baja, independiente de la estación del año o del área de que se trate. La mayor biomasa ocurre sobre la plataforma en profundidades bajas, pero su magnitud varía dependiendo del área y de la época. La biomasa frente a Campeche no depende de las descargas de aguas continentales sino se genera sobre la plataforma de Yucatán

Vertical distribution of zooplankton biomass and ichthyoplankton density during an annual cycle on the continental shelf of the southern Gulf of Mexico

Se analizó estacionalmente la biomasa zooplanctónica (BZ) y la densidad ictioplanctónica (DI) en la columna de agua sobre la plataforma continental del sur del Golfo de México, para determinar sus patrones de distribución vertical y establecer si existe una relación entre ambos componentes. Se muestrearon cinco niveles de profundidad: 0-6 m, 6-12 m, 12-18 m, 45-55 m y 95-105 m. El patrón de distribución vertical de la BZ y de la DI fue similar en todas las épocas de muestreo, con la mayor concentración de organismos en los niveles superficiales y la más baja en los niveles más profundos. Estos resultados sugieren que la columna de agua en el área de estudio puede estar dividida en una capa superficial (0 a 18 m) y una capa profunda (45 a 100 m) y que las diferencias estacionales pueden ser atribuidas a los procesos de mezcla. Esta diferencia entre las capas superficiales y las profundas ocurre porque, en general, las capas superficiales de la columna de agua son las más productivas. La relación entre la BZ y la DI fue positiva y significativa (ANCOVA, P<0,05) a través de las épocas de muestreo y en la mayoría de las profundidades probablemente porque el ciclo de producción es continuo en el sur del Golfo de México como sucede en áreas tropicales y subtropicales, manteniendo la disponibilidad de alimento y consecuentemente, la relación depredador-presa. La relación BZ y DI en la columna de agua es afectada principalmente por la variación estacional de las descargas de agua continental y el proceso de mezcl

Larval abundance variation of Bregmaceros cantori Milliken & Houde, 1984, related to the El Niño events (1987-1996), southern Gulf of Mexico

The influence of the El Niño Southern Oscillation (ENSO) on the abundance variation of fish larvae of Bregmaceros cantori in the southern Gulf of Mexico was analyzed. The study was conducted between 1987 and 1996, using 20 oceanographic cruises. The larval abundance of B. cantori was related to: (1) the sea surface temperature anomaly (SSTA) in the central equatorial Pacific Ocean; (2) the average temperature surface layer, to 30 m, obtained from cruises data; (3) the continental water discharges data from the continental hydrological station nearest to the study area. The variability of B. cantori larval abundance was high throughout the sampling period and no seasonal pattern was detected. During the study period, three events of El Niño occurred: in 1987, 1992 and 1995. Statistical analyses indicated significant differences of the larvae abundance of B. cantori between El Niño and normal years, i.e, years without El Niño. High abundances of fish larvae were found during El Niño years. Higher abundances of B. cantori larvae, during El Niño years, are possibly associated to predator-prey relationshipsSe analiza la influencia de El Niño Oscilación del Sur (ENSO) sobre la variación de la abundancia de las larvas del pez Bregmaceros cantori en el sur del Golfo de México. El estudio se desarrolló entre 1987 y 1996, usando 20 cruceros oceanográficos. La abundancia de B. cantori fue relacionada con: (1) la anomalía de la temperatura superficial del mar (SSTA) del Océano Pacífico central ecuatorial, (2) la temperatura promedio de la capa superficial de 30 m, de datos de las campañas, (3) las descargas de aguas continentales con datos provenientes de la estación hidrológica mas cercana al área de estudio. Hubo una alta variabilidad de la abundancia de larvas de B. cantori a través del tiempo, pero no se registró un patrón estacional. Durante el periodo de estudio ocurrieron tres eventos de El Niño: 1987, 1992 y 1995. Los análisis estadísticos indicaron diferencias significativas en la abundancia de larvas entre los años de El Niño y años normales, sin el evento de El Niño. Se encontraron altas abundancias de B. cantori en los periodos de El Niño en comparación con los años normales. Es posible que las mayores abundancias de larvas de B. cantori durante años de El Niño estén asociadas con relaciones depredador-pres