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118 resultados encontrados para: TEMA: Río Usumacinta
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1.
Libro
Análisis de la producción agropecuaria y de los recursos naturales en la región Usumacinta / Stefan Arriaga Weiss, Juan Caldera Noriega, Roberto Castro González, ...[et al.]
Arriaga Weiss, Stefan Louis ; Caldera Noriega, Juan (coaut.) ; Castro González, Roberto (coaut.) ;
Villahermosa, Tabasco, México : Centro de Investigación y Enseñanza en Ecosistemas Tropicales , s.f.
Clasificación: T/333.707263 / A5
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
SFA001979 (Disponible)
Disponibles para prestamo: 1

2.
Libro
Datos hidrológicos de sitios en estudio para aprovechamientos hidroeléctricos y estaciones climatológicas: hasta diciembre 1973
Comisión Federal de Electricidad (México) ;
Distrito Federal, México : Comisión Federal de Electricidad , s.f.
Clasificación: C CH/551.570212 / C6
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
SFC000036 (Disponible) , SFC000035 (Disponible)
Disponibles para prestamo: 2

3.
Artículo
*Solicítelo con su bibliotecario/a
Applicability of biodiversity databases to regional conservation planning in the tropics: a case study evaluation of the effect of environmental bias on the performance of predictive models of species richness
Vaca Genuit, Raúl Abel (autor) ; Rodiles Hernández, María del Rocío (autora) (1956-) ; Soria Barreto, Miriam (autora) ; Muñoz Alonso, Luis Antonio (autor) ; González Díaz, Alfonso Ángel (autor) ; Castillo Santiago, Miguel Ángel (autor) ;
Disponible en línea
Contenido en: Acta Oecologica Volumen 109, artículo número 103653 (November 2020), páginas 1-13 ISSN: 1146-609X
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

The biodiversity data typically available for fitting distributional models in the tropics come from museum and scientific collections which are often incomplete and prone to sampling and environmental biases. Nevertheless, most studies undertaken in tropical regions assume that collection data offers a satisfactory environmental coverage without any quantitative assessment. In this study, we investigate the effects of differences in environmental bias and coverage provided by distributional data when aggregated into different grid cell sizes, on the performance of species richness-environment models and predictions. We use an extensive data compilation, including national and regional collections, on the distribution of amphibians, reptiles and fishes in the hydrologic region of the Usumacinta River as a case study. General additive models and environmental variables are used to construct predictive models at 40, 20, 10 and 5 km grid resolutions, based on well-sampled cells. The best multivariate models included nonparametric interaction terms for the effects of precipitation and temperature and suggested an altitudinal shift in the relative importance of energy and water in determining the distribution of species richness.

For fishes, geomorphology accounted for fine scale variation in species richness along the hydrologic network, indicated by peaks in species diversity at the junction of the major rivers where major accumulation of water and sediments occurs. For all taxonomic groups, we found that sampling biases deviated most from the mean bias at the extremes of gradients accounting for important environmental factors. The pattern of environmental bias changed with grid size, with the form and amount of change being casespecific. Biases affected distribution predictions when compared with unbiased datasets. Moreover, not all models resulted best at coarser resolution as it is commonly assumed. Our results demonstrate that bias in the available data must be evaluated before mapping biodiversity distributions, irrespective of the choice of scale.


4.
Artículo
Resumen en: Inglés |
Resumen en inglés

In this study, bone char (BC) from pleco fish (Pterygoplichthys spp.) was synthesized, and their textural and physicochemical properties, as well as its adsorption capacity towards fluoride and Cd(II) from single and binary aqueous solutions, were determined. The results showed that the properties of the BCs were independent of the type of bone used and the surface areas were close to 110 m² g−¹. The effect of solution pH revealed that the adsorption capacity of BC towards fluoride from water raised by decreasing the solution pH. This trend was attributed to the electrostatic interaction between the positively charged surface and the fluoride in aqueous solution. On the contrary, the capacity of BC for adsorbing Cd(II) was enhanced by increasing the solution pH, indicating that electrostatic interactions were also essential but with a contrary effect in comparison with fluoride adsorption due to the negatively charged surface at pH above the point zero charge (pHPZC = 8.16). The experimental data for binary adsorption of fluoride and Cd(II) were interpreted satisfactorily using the modified Freundlich multicomponent isotherm (EFMI), and the experimental data revealed that Cd(II) have an antagonistic effect on the adsorption of fluoride, whereas the presence of fluoride does not affect the capacity of BC for adsorbing Cd(II). Thermogravimetric, XRD diffraction and IR spectroscopy analysis corroborated that the adsorption of fluoride in BC is due to electrostatic attractions, ion exchange or chemisorption and physisorption. Besides, the removal of Cd(II) occurs by physical adsorption and ion exchange. It was concluded that BC is an alternative material for the removal of fluoride and Cd(II) from aqueous solutions, and it is a possible application for using the bones of this invasive fish species.


5.
Artículo
Los árboles más altos de la cuenca del Usumacinta
Martínez Camilo, Rubén (autor) ; Jiménez López, Derio Antonio (autor) ;
Disponible en línea
Contenido en: ECOfronteras Volumen 24, número 69 (mayo/agosto 2020), páginas 6-9 ISSN: 2007-4549
PDF PDF
Resumen en: Español |
Resumen en español

En la cuenca del río Usumacinta podría haber hasta 7,500 especies de plantas; en el libro La vegetación de Chiapas (1952) se menciona un árbol (olmo mexicano) que midió 87 metros de alto en la Sierra Madre de Chiapas, mientras que el de mayor diámetro del mundo está en Oaxaca. Estos son solo unos datos que muestran la magnificencia de nuestra vegetación y las posibilidades que ofrecen los árboles por su valor escénico, y aún se vislumbran sorpresas de altura en la inmensa biodiversidad del sur-sureste de México.


6.
- Artículo con arbitraje
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Resumen en: Inglés |
Resumen en inglés

There is increasing recognition that ecosystems and their services need to be managed at landscape scale and greater. The development of landscape-scale conservation strategies need to incorporate information from multiple sources. In this study, we combine various research tools to link landscape patterns with production units and systems in the Usumacinta River Basin, and inform the discussion of key questions around decisionmaking related to conservation action and policy in Southern Mexico. A typology based on policy-relevant farmer characteristics (land tenure, farm size, source of income, farming system) differentiated between farmers (traditional vs. cattle ranching) with different motivations that determine how management affects landscape configuration. Five main types of traditional farming systems were identified that combine different forms of land use and vary in their degree of land intensification. Major fragmentation and decrease in connectivity coincided spatially with floodplains dominated by large-scale commercial farms that specialize in livestock production.

Traditional practices within large units with low-sloped high quality land were also seen to be intensive; however the presence of trees was notable throughout these units. Policies that promote livestock farming are among the principle causes motivating deforestation. Land intensification by traditional farmers decreased as the landscape became increasingly rugged. Traditional farmers are the focus of initiatives developed by the Biological Corridor project which seeks to increase forest cover and landscape connectivity. These initiatives have shown high levels of rural participation (10,010 farmers benefited from 27,778 projects involving 95,374 ha of land) and acceptance (producers carried out more than one project and several types of projects during the first eight years of work). Strong action is still required to take on the segment of large-scale ranchers. Changes in the structure of land tenure over the past decade are highlighted that could have a profound impact on conservation policies and programs.


7.
Artículo
Experimental validation of a cohesive suspended sediment transport model for two Mexican rivers
García Aragón, Juan Antonio (autor) ; Izquierdo Ayala, Klever (autor) ; Castillo Uzcanga, María Mercedes (autora) ; Carrillo Bibriezca, Laura (autora) ; Salinas Tapia, Humberto (autor) ;
Disponible en línea
Contenido en: Environmental Systems Research Volumen 8, número 12 (2019), p. 1-20 ISSN: 2193-2697
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Resumen en: Inglés |
Resumen en inglés

Background: The south of Mexico is the least developed part of the country but its basins generate more than 60% of the country’s available water. Though disturbances to the rivers caused by development are still low, there is concern about the environmental health of the rivers. The calculation of the sediment load with a focus in fine fraction, where nutrients are found, is a priority. However, models for suspended sediment transport in large rivers are difficult to formulate because they carry a large amount of cohesive sediments, those cohesive sediments form aggregates or flocs with primary particles that are less than 65 μm. The hydrodynamic behavior of flocs depends on their size, density and shape, which differs from that of non‑cohesive sediments as theirs depends on their interaction with the water column. A classical model to calculate suspended sediment concentration profiles for steady flow conditions is the Rouse equation, which has been extensively validated for non‑cohesive suspended sediment. Some authors have demonstrated that when applied in some large rivers in conjunction with non‑cohesive settling velocity models it does not perform very well. The difficulty comes from the fact that most of the suspended sediment charge in large rivers is constituted by cohesive sediments.

Results: Suspended sediments from Mexico’s two largest rivers Usumacinta and Grijalva, with a mean flow rate near river mouth of 2020 m³/s and 1150 m³/s respectively, were analyzed in a rotating annular flume (RAF). The shear velocity obtained in the field by ADCP was reproduced in the annular flume, the size and shape of flocs were obtained by means of PTV. Settling velocity was also obtained to calibrate a settling velocity model appropriate for cohesive sediments. Conclusions: The settling velocity model developed for cohesive sediments in conjunction with the Rouse equation allowed the reproduction of suspended sediment concentration profiles for the rivers Usumacinta and Grijalva. The estimated concentration profiles were compared and validated with the measured concentration profiles in the field. Thus, the model obtained through this research can be used to estimate nutrient delivery to the sea from the largest rivers in Mexico.


8.
- Artículo con arbitraje
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Resumen en: Inglés |
Resumen en inglés

The Lacantun Catfish, Lacantunia enigmatica, is reported for the first time in the Usumacinta river basin in Guatemala. Two specimens were collected in the Usumacinta tributaries Río La Pasión and Río Negro, which are characterized by seasonally fast-flowing deep channels and high fluctuations in water-level. We present a map with new records, and a brief description, and images of the specimens collected.


9.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Relationship among physicochemical conditions, chlorophyll-a concentration, and water level in a tropical river–floodplain system
Cruz Ramírez, Allan K. (autor) ; Salcedo Meza, Miguel Ángel (autor) ; Sánchez, A. J. (coaut.) ; Barba Macías, Everardo (autor) ; Mendoza Palacios, Juan de Dios (autor) ;
Contenido en: International Journal of Environmental Science and Technology Vol. 16, no. 7 (July 2019), p. 3869-3876 ISSN: 1735-2630
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Resumen en: Inglés |
Resumen en inglés

The free-flowing Usumacinta River maintains an average annual water-level fluctuation of 6.7 m. This study evaluated relationships between 14 physicochemical and biological variables and key factors in four water-level conditions in a river–floodplain system. The analysis incorporated intra-annual variation in all variables, with each selected in accordance with multiple statistical and physicochemical criteria. Possible correlations were examined as a function of various physicochemical and biological factors at each water level. Within the study area, defined by a temporal gradient in principal component 1, the yearly river overflow above the bankfull stage is characterized by water with a low level of total suspended solids. Data on riverine wetlands suggest that seasonal changes are key to determining intra- and inter-annual chlorophyll-a levels and water clarity. However, opposite trends are observed for high and low water-level conditions. Nutrient enrichment cannot be taken as the key physicochemical factor of water level, under either water-level conditions, due to the lack of a temporal gradient in principal component 2 and the high biochemical variability of nitrate and orthophosphate levels. In conclusion, the hypothesis was accepted for the production of phytoplankton biomass and light attenuation at low and high water levels, as both were dependent on intra-annual changes. The increases in chlorophyll-a related to the minimal variability at the lowest water level open the opportunity to gauge this relationship as a possible environmental predictor for river–floodplain systems.


10.
Artículo
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Species richness of urban and rural fish assemblages in the Grijalva Basin floodplain, southern Gulf of Mexico
Sánchez Martínez, Alberto de Jesús (autor) ; Álvarez Pliego, Nicolás (autor) ; Espinosa Pérez, Héctor (autor) ; Florido Araujo, Rosa Amanda (autora) ; Macossay Cortez, Alberto (autor) ; Barba Macías, Everardo (autor) ; Salcedo Meza, Miguel Ángel (autor) ; Garrido Mora, Arturo (autor) ;
Disponible en línea
Contenido en: Cybium Volumen 43, número 3 (April 2019), páginas 239-254 ISSN: 2101-0315
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Resumen en: Inglés | Frances |
Resumen en inglés

Urban sprawl poses a major threat to aquatic biodiversity. The species richness in fish assemblages of fifteen ecosystems with different degrees of hydraulic connectivity in the floodplain of the Grijalva River watershed has been analysed and described along five years. After human interventions, four lagoons are permanently disconnected and three are temporarily connected. The other three lagoons stay permanently interconnected. Native cichlids and poeciliids dominated in number of species, representing 24 of the 55 listed species. These 55 species include six non-native invasive species in the Usumacinta Province. The lowest number of species was recorded in urban lagoons, while they were similar in rural lagoons and rivers. In addition, 60% of the fish absent in the lagoons of the Metropolitan Area of Villahermosa (MAV) are species with a marine or an estuarine affinity; thus, the permanently disconnected MAV lagoons have seven species less than the permanently connected rural lagoons. Diversity corresponds to that reported in the literature. In urban lagoons, low diversity and the high percentage of lacking fish with a marine or an estuarine affinity indicate that ichthyological diversity is favoured by the interconnection of rivers and rural lagoons in the floodplain of the Grijalva River Basin.

Resumen en frances

L’expansion urbaine est une menace pour la biodiversité aquatique. La richesse en espèces dans des assemblages de poissons de quinze écosystèmes avec différents degrés de connectivité hydraulique situés dans la plaine inondable du bassin versant du fleuve Grijalva a été analysée et décrite au cours de cinq années. Suite à des interventions humaines, quatre lagunes sont déconnectées en permanence et trois sont temporairement connectées. Trois autres lagunes restent interconnectées en permanence. Les cichlidés et les poeciliidés natifs dominent en nombre d’espèces, représentant 24 des 55 espèces répertoriées. Ces 55 espèces incluent 6 espèces invasives non indigènes in the Usumacinta Province. Les diversités spécifiques les plus faibles ont été enregistrées dans les lagunes urbaines, tandis qu’elles plus importantes et similaires dans les lagunes et les rivières rurales. De plus, 60% des poissons absents dans les lagunes de la Région Métropolitaine de Villahermosa (MAV) sont des espèces ayant une affinité marine ou estuarienne. Les lagunes MAV déconnectées en permanence comptaient sept espèces de moins que les lagunes rurales connectées en permanence. La diversité correspond à celle rapportée dans la littérature. Une faible diversité et l’absence de poissons ayant une affinité marine ou estuarienne dans les lagunes urbaines indiquent que la diversité ichtyologique est favorisée par l’interconnexion des rivières et lagunes rurales situées dans la plaine inondable du bassin du fleuve Grijalva.