Relación entre capturas del tiburón Rhizoprionodon terraenovae al sur del Golfo de México y el número de manchas solares

Background. The Antillean or sharpnose shark is one of the main exemplars of shark species in the commercial catch in southern Gulf of Mexico. Oceanic dynamics on the planet Earth varies year-on-year due to the oscillation of solar radiation; fish abundances (and catches) likely respond to these oscillations. Goals. This study focuses on the analysis of landings variability of the antillean sharpnose shark (Rhizoprionodon terraenovae) in the Mexican coast of the Gulf of Mexico, from 1940 to 2006, and its possible connection with solar activity as assessed by the average sunspot number (Zürich Index). Methods. A polynomial curve by least-squares best fitting was used to eliminate the tendency from the sharpnose shark landings time series. Spectral techniques of Maximum Entropy (ME) and Fast Fourier Transform (FFT) were used to analyze the time series of sharpnose shark landings and the Zürich Index. Results. The time series of sharpnose shark landings showed a remarkable spectral peak with a period of about 12.8 years, while the Zürich Index showed a marked peak at a period of 11.6 years. Cross-correlation revealed a delay between the average number of solar spots and sharpnose shark landings. Conclusions. This work is the first to report such a low frequency variability for landings of the Rh. terraenovae fishery in the Gulf of Mexico, using a particular methodology that can provide information for the design of predictive models in the future. The analyzed landing volumes of the sharpnose shark Rh. terraenovae showed as a result a periodical behavior in coincidence with Wolfs solar activity cycle of 10.6 years.Antecedentes. El cazón antillano ó tiburón picudo, es uno de los ejemplares principales de las especies de tiburón en la captura comercial en el sur del Golfo de México. La dinámica oceánica en el planeta tierra varía de forma interanual debido a la oscilación de la radiación solar; las abundancias (y capturas) de peces responden a estas oscilaciones. Objetivos. Analizar la variabilidad de las capturas del cazón antillano Rhizoprionodon terraenovae en el litoral mexicano del Golfo de México, de 1940 a 2006 y su posible relación con la actividad solar, evaluada mediante el número promedio de manchas solares (Índice de Zürich). Métodos. Se empleó el polinomio de mejor ajuste por mínimos cuadrados para eliminar la tendencia de la serie temporal de las capturas; y se utilizaron las técnicas espectrales de la Transformada Rápida de Fourier (FFT) y de Máxima Entropía (ME) para analizar las series temporales de las capturas de cazón y del índice de Zürich. Resultados. Se muestra un pico espectral distintivo en la serie de capturas con una frecuencia de alrededor de 12.8 años, en tanto que el índice de Zürich muestra un pico marcado a los 11.6 años. La correlación cruzada reveló un retraso entre el número promedio de manchas solares y las capturas de tiburón. Conclusiones. Este trabajo es el primero en reportar una frecuencia tan baja en la variabilidad de las capturas de la pesquería de Rh. terraenovae del Golfo de México, empleando una metodología particular que puede proporcionar información para el diseño de modelos predictivos en el futuro. Los volúmenes de captura analizados del cazón antillano Rh. terraenovae mostraron como resultado un comportamiento periódico en coincidencia con el ciclo de actividad solar de Wolf de 10.6 años

Use of constructed wetlands for the treatment of water from an experimental channel at Xochimilco, Mexico

Two constructed wetlands were designed and their performance in the treatment of water from Cuemanco, in an experimental channel at Xochimilco, Mexico was assessed. One of them employed emergent macrophytes (Scirpus americanus) and the other one used floating macrophytes (the duckweed Lemna gibba). The system was stabilized for five months. Water quality was improved after 220 days of treatment, as organic matter (assessed as DQO) was removed from 43.38% to 58.52% by employing L. gibba and S. americanus, respectively. Nutrient removal significatively (P < 0.05) differed between the two treatments and the control, as 86.35% and 80.33% of ammonia, 89.47% and 90.23% of nitrite, and 38.44% and 50.20% of reactive phosphorus were removed by S. americanus and L. gibba, respectively. On the other hand, water pH changed from alkaline values to neutrality after the treatment, an important issue as this water is employed for cultured land irrigation

Evidence of spatial clustering of childhood acute lymphoblastic leukemia cases in Greater Mexico City: report from the Mexican Inter-Institutional Group for the identification of the causes of childhood leukemia

BackgroundA heterogeneous geographic distribution of childhood acute lymphoblastic leukemia (ALL) cases has been described, possibly, related to the presence of different environmental factors. The aim of the present study was to explore the geographical distribution of childhood ALL cases in Greater Mexico City (GMC).MethodsA population-based case-control study was conducted. Children <18 years old, newly diagnosed with ALL and residents of GMC were included. Controls were patients without leukemia recruited from second-level public hospitals, frequency-matched by sex, age, and health institution with the cases. The residence address where the patients lived during the last year before diagnosis (cases) or the interview (controls) was used for geolocation. Kulldorff’s spatial scan statistic was used to detect spatial clusters (SCs). Relative risks (RR), associated p-value and number of cases included for each cluster were obtained.ResultsA total of 1054 cases with ALL were analyzed. Of these, 408 (38.7%) were distributed across eight SCs detected. A relative risk of 1.61 (p<0.0001) was observed for the main cluster. Similar results were noted for the remaining seven ones. Additionally, a proximity between SCs, electrical installations and petrochemical facilities was observed.ConclusionsThe identification of SCs in certain regions of GMC suggest the possible role of environmental factors in the etiology of childhood ALL

Caracterización de las comunidades de sifonóforos del Golfo de California 1984-1986.

impreso y digita

Asociaciones interespecificas de copépodos en la costa oeste de Baja California Sur, México

The analysis of copepod communities of the Baja California Sur coast during May 1984 and 1986 and July 1987 and 1988, shows that the most important feature of this taxocoenosis is the dominance of Calanus pacificus, a transitional species. Other recurrent secies were: Pleuromamma abdominalis and Calanus minor, both belonging to the warm water biota and are integrated into a group that constantly occurs in the region. As observed through the rank abundance analysis. Acartia danae, Rhincalanus nasutus and Euchaeta marina, are semi-permanent elements of the recurrent species group. May 1984 and 1986 species diversity averages were higher than in July 1987 and 1988, these values being associated to positive temperature anomalies in 1984 and 1986 as well as to negative anomalies in 1987 and 988. A cluster analysis of the copepod species groups indicates that there exists some degree of flexibility in their integration from one survey to the other, thus reflecting the variability of th hydrological features prevaling at this region.El análisis de las comunidades de copépodos en la costa del Pacífico de Baja California Sur, durante mayo de 1984 y 1986 y julio de 1987 y 1988, indica que el apecto más notable de esta taxocenosis es la dominancia de Calanus pacificus, una especie transicional. Otras especies recurrentes son Pleuromamma abdominalis y Calanus minor características de aguas cálidas yq ue constituyen un grupo de constante presencia en la zona, aunque su posición jeráquica no es siempre la misma; así lo sugiere el análisis de rango-abundancia. Acartia danae, Rhincalanus nasutus y Euchaeta marina, son especies semipermanentes en el grupo de recurrentes. En mayo de 1984 y 1986, los valores promedio de diversidad específica fueron mayores que los de julio de 1987 y 1988, lo cual se asocia a anomalías térmicas positivas en 1984 y 1986 y negatias en 1987 y 1988. El análisi de conglomerados indica que hay cierto grado de flexibilidad en la integración de los grupos de especies de un muestreo a otro, que refleja la variabilidad en as condiciones hidrológicas de la región

Evidences for a shift in barometric pressure, air temperature and rainfall patterns circa 1920, and its possible relation to solar activity

A survey of 300 metereological stations worlwide located showed that nearly half of the stations presented a pattern change in the corelations between the sunspot number and barometric pressure, air temperature and precipitatio, around 1920. This change was mainly  fom a negative correlation to a positive correlation. Furthermore, we also found strong correlations between sunspots and pressure and precipitation in both tropical and extratropical latitudes; for the temperature the strong correlations appear mainly in extratropical zones

Análisis temporal y espacial físicoquímico de una laguna tropical a través del análisis multivariado

This study analyses spatial and temporal variations in temperture, salinity, silicate and orthophosphate in the water of Tampamachoco lagoon, Veracruz (México), from 1979 to 1986. Multivariate analysis was applied to distinguish water types during the three climatic seasons of the region. Principal components analysis defined three areas in the lagoon: (1) and estuarine-marine area characterized by a low content of silicates (3.37 to 5.44 ug-at/I), (2) an intermediate area that makes up the main body of the lagoon with a strong temporal and spatial variation and a wide range of SiO3 concentrations (7.04 to 14.71 ug-at/I) and (3) the area of shallow inner lagoons with low levels of SiO3 (4 to 8.47 ug-at/I). These areas varied during the three climatic seasons: nothers, dry and rainy season. The variation explained by silicate during the three seasons were 57%, 56% and 42%, respectively.Se analiza la variación espacial y temporal de temperatura, salinidad, silicatos y ortofosfatos del agua de la Laguna de Tampamachoco, Veracruz, durante el período de 1979 a 1986 mediante el uso del análisis multivariado aplicado (Análisis Cluster y Componentes Principales) a las tres épocas climáticas de la región. Se delimitaron tres áreas caracteristicas: (1) la estuarina-marina caracterizada por un bajo contenido de silicatos (3.37 a 5.44 ug-at/I), (2) la intermedia que constituye el cuerpo principal de la laguna con una fuerte variante temporal y espacial en su área de cobertura y con un apmlio intervalo de concentración de SiO3(7.04 a 14.71 ug-at/I) y (3) la de las lagunetas de escasa profundidad y bajos niveles de SiO3 (4 a 8.47 ug-at/I); dichas áreas se modifican en cobertura de acuerdo a las tres temporadas climáticas: "nortes", secas y lluvias, durante las cuales los silicatos explicaron dicho patrón en un 57%, 56% y 42% respectivamente

Non-Binary Snow Index for Multi-Component Surfaces

A Non-Binary Snow Index for Multi-Component Surfaces (NBSI-MS) is proposed to map snow/ice cover. The NBSI-MS is based on the spectral characteristics of different Land Cover Types (LCTs) such as snow, water, vegetation, bare land, impervious, and shadow surfaces. This index can increase the separability between NBSI-MS values corresponding to snow from other LCTs and accurately delineate the snow/ice cover in non-binary maps. To test the robustness of the NBSI-MS, Greenland and France-Italy regions were examined where snow interacts with highly diversified geographical ecosystem. Data recorded by Landsat 5 TM, Landsat 8 OLI, and Sentinel-2A MSI satellites have been used. The NBSI-MS performance was also compared against the well-known NDSI, NDSII-1, S3, and SWI methods and evaluated based on Ground Reference Test Pixels (GRTPs) over non-binarized results. The results show that the NBSI-MS achieves overall accuracy (OA) ranging from 0.99 to 1 with kappa coefficient values in the same range as OA. The precision assessment confirms the performance superiority of the proposed NBSI-MS method for removing water and shadow surfaces over the compared relevant indices.Comment: 22 pages, 12 figure