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17 resultados encontrados para: AUTOR: Sepúlveda Lozada, Alejandra
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1.
Artículo
Microbios acuáticos: diminutos protagonistas de historias gigantes
Sepúlveda Lozada, Alejandra (autora) ; Castillo Uzcanga, María Mercedes (autora) ;
Disponible en línea
Contenido en: ECOfronteras Volumen 24, número 69 (mayo/agosto 2020), páginas 2-5 ISSN: 2007-4549
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Resumen en: Español |
Resumen en español

Hicieron la vida posible hace millones de años y siguen siendo indispensables, ya sea que nos enfoquemos en su relación con el oxígeno, el carbono o el nitrógeno, o bien, en su papel en las redes tróficas y en que procesan casi cualquier tipo de materia orgánica en este enorme territorio de transformaciones que es nuestro mundo. Las bacterias y las arqueas son aún materia de estudio, pero lo que ya sabemos es asombroso.


2.
- Capítulo de libro
Estudio de caso: importancia de las zonas estuarinas de la Reserva de la Biosfera Pantanos de Centla para la conservación de la biodiversidad de peces
Mendoza Carranza, Manuel (autor) ; Arévalo Frías, Wendi del Carmen (autora) ; Sepúlveda Lozada, Alejandra (autora) ;
Contenido en: La biodiversidad en Tabasco. Estudio de estado / coordinación y seguimiento general: Andrea Cruz Angón, Jorge Cruz Medina, Jessica Valero Padilla, Flor Paulina Rodríguez Reynaga, Erika Daniela Melgarejo Distrito Federal, México : Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, 2019 Vol. III, página 206-211 ISBN:978-6078570225 (Vol. III)
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3.
- Artículo con arbitraje
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Luis Alejandro Yáñez-Arancibia 1944-2016
Day, John W. (autor) (1945-) ; Sánchez Gil, Patricia (autora) ; Sepúlveda Lozada, Alejandra (autora) ;
Disponible en línea
Contenido en: Journal of Fish Biology Vol. 92 (2018), p. 293–297 ISSN: 1095-8649
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4.
- Artículo con arbitraje
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Flood pulse induced changes in isotopic niche and resource utilization of consumers in a Mexican floodplain system
Sepúlveda Lozada, Alejandra ; Saint Paul, Ulrich (coaut.) ; Mendoza Carranza, Manuel (coaut.) ; Wolff, Matthias (coaut.) ; Yáñez Arancibia, Alejandro (coaut.) ;
Contenido en: Aquatic Sciences Vol. 79, no. 3 (July 2017), p. 597–616 ISSN: 1420-9055
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Resumen en: Inglés |
Resumen en inglés

Tropical coastal ecosystems of the southern Gulf of Mexico including marshes, mangroves and seagrasses of Centla Wetlands and Terminos Lagoon (Grijalva-Usumacinta delta) are known to host a high diversity of aquatic consumers. Nevertheless, the limited research focusing on the energy fluxes that sustain consumers has as yet neither considered the strong seasonality of these systems, nor the linkage of the trophic flow patterns with ecosystem functioning. The present work analyses and compares stable isotope ratios (δ¹³C and δ ¹³5N) of consumers during the dry and rainy season at different wetland sites to determine their resource utilization. The sites compared comprise three fluvio-lagoons and a coastal mangrove creek that differ in vegetational characteristics, distance to the sea, and freshwater input. The results support the hypothesis that a larger isotopic niche breadth of consumers prevails during the rainy season, when resource availability is supposedly higher. This translates into an increase in resource use diversification by consumers and corroborates the flood pulse concept (FPC), which can be particularly applied to those habitats with high riverine influence in the study area (e.g., fluvio-lagoons). However, the FPC alone cannot be applied to understand the main factors influencing the fate and utilization of basal resources in areas interacting more actively with the sea, and therefore further extensions and/or complementary conceptual approaches considering marine systems highly interconnected with coastal floodplains should be considered.


5.
- Artículo con arbitraje
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Distribution and bioconcentration of heavy metals in a tropical aquatic food web: a case study of a tropical estuarine lagoon in SE Mexico
Mendoza Carranza, Manuel (coaut.) ; Sepúlveda Lozada, Alejandra (coaut.) ; Dias Ferreira, Celia (coaut.) ; Geissen Geissen, Violette (coaut.) ;
Contenido en: Environmental Pollution Vol. 210 (March 2016), p. 155-165 ISSN: 0269-7491
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Resumen en: Inglés |
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Despite the increasing impact of heavy metal pollution in southern Mexico due to urban growth and agricultural and petroleum activities, few studies have focused on the behavior and relationships of these pollutants in the biotic and abiotic components of aquatic environments. Here, we studied the bioaccumulation of heavy metals (Cd, Cr, Ni, Pb, V, Zn) in suspended load, sediment, primary producers, mollusks, crustaceans, and fish, in a deltaic lagoon habitat in the Tabasco coast, with the aim to assess the potential ecological risk in that important wetland. Zn showed the highest concentrations, e.g., in suspended load (mean of 159.58 mg kg-¹) and aquatic consumers (15.43─171.71 mg kg-¹), particularly Brachyura larvae and ichthyoplankton (112.22─171.71 mg kg-¹), followed by omnivore Callinectes sp. crabs (113.81─128.07 mg kg-¹). The highest bioconcentration factors (BCF) of Zn were observed for planktivore and omnivore crustaceans (3.06─3.08). Zn showed a pattern of distribution in the food web through two pathways: the pelagic (where the higher concentrations were found), and the benthic (marsh plants, sediment, mollusk, fish).

The other heavy metals had lower occurrences in the food web. Nevertheless, high concentrations of Ni and Cr were found in phytoplankton and sediment (37.62─119.97 mg kg-¹), and V in epiphytes (68.64 mg kg-¹). Ni, Cr, and Cd concentrations in sediments surpassed international and national threshold values, and Cd entailed a “considerable” potential risk. These heavy metals are most likely transferred into the food web up to fishes through the benthic pathway. Most of the collected fishes are residents in this type of habitat and have commercial importance. Our results show that the total potential ecological risk in the area can be considered as “moderate” . Nevertheless, heavy metal values were similar or surpassed the values from other highly industrialized tropical coastal regions.


6.
- Artículo con arbitraje
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Differences in food web structure of mangroves and freshwater marshes: evidence from stable isotope studies in the Southern Gulf of Mexico
Sepúlveda Lozada, Alejandra ; Mendoza Carranza, Manuel (coaut.) ; Wolff, Matthias (coaut.) ; Saint Paul, Ulrich (coaut.) ; Ponce Mendoza, Alejandro (coaut.) ;
Contenido en: Wetlands Ecology and Management Vol. 23, no. 2 (April 2015), p. 293-314 ISSN: 1572-9834
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Resumen en: Inglés |
Resumen en inglés

Tropical coastal habitats like marshes, mangroves, and submerged grasses comprise diverse plant and animal communities and a certain degree of connectivity with other ecosystems. We compared the food web structure of a fringing mangrove-seagrass habitat and three fluvio-lagoons with marsh-eelgrass and mangrove-bare sediments during a dry season in Terminos Lagoon and Centla Wetlands, Southern Gulf of Mexico. Analysis of d13C and d15N stable isotopes in tissues of aquatic consumers, primary producers, and other carbon sources, in combination with isotope- based Bayesian methods, were performed to determine the main food sources and the isotopic niche of the consumers’ communities. Consumers in the man- grove-seagrass site showed high dependence on phytoplankton (average contribution 31 %), macroal- gae (20 %) and organic matter derived from seagrass- es (17 %). In the fluvio-lagoons, consumers showed high dependence on marginal vegetation (16–46 %). Phytoplankton and mangrove epiphytes comprised other important resources at these sites (with contri- butions of 24–44 %). The isotopic niche of consumers from the fringing mangrove-seagrass site did not overlap with those from the fluvio-lagoons. Moreover, despite the predominance of generalist consumers in all sites, differences in their isotopic niche area were observed, with consumers from the marsh-eelgrass site showing the narrowest. This suggests that con- sumer resource availability greatly differs in these habitats. Our results provide valuable information that help increase our understanding about the trophic structure in these important estuarine systems.


7.
CD
XVIII congreso mexicano de botánica: la botánica nacional en el bicentenario de la independencia [Disco compacto] / editores: Georgina Vargas Amado, Ofelia Vargas Ponce, Aarón Rodríguez Contreras, Mollie Harker, Ana Sofia Monroy Sais
Memoria del XVIII Congreso Mexicano de Botánica (2010) ;
Guadalajara, Jalisco, México : Prometeo Editores , 2010
Clasificación: DC/581.972 / M4
Bibliotecas: Villahermosa
Cerrar
SIBE Villahermosa
ECO050005329 (Para consulta)
Disponibles para prestamo: 0
Índice

1. Presentación
2. Directorio
Sociedad Botánica de México, A.C.
Comité Organizador del XVIII Congreso Mexicano de Botánica
Universidad de Guadalajara
Universidad Autónoma Metropolitana
3. Patrocinadores
4. Agradecimientos
5. Salones del Hotel Fiesta Americana Guadalajara
6. Mapa de la sede del Congreso
7. Programa general
8. Programa sintético
9. Resúmenes de conferencias magistrales
10. Resúmenes de simposios y ponencias orales dentro de cada simposio
11. Resúmenes de reuniones satélite
12. Resúmenes de mesas redondas
13. Resúmenes de cursos y talleres
14. Programa detallado de simposios
Lunes 22 de noviembre
Martes 23 de noviembre
Jueves 25 de noviembre
Viernes 26 de noviembre
15. Resúmenes de carteles
16. Exposiciones


8.
Capítulo de libro
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Erosión fluvial y especies potenciales para la restauración de humedales en Pantanos de Centla, Tabasco
Ochoa Gaona, Susana (autora) ; Zamora Cornelio, Luis Felipe (autor) ; Geissen Geissen, Violette (autora) ; Sepúlveda Lozada, Alejandra (autora) ; Jarquín Sánchez, Aarón (autor) ;
Contenido en: XVIII congreso mexicano de botánica: la botánica nacional en el bicentenario de la independencia [Disco compactoe] Guadalajara, Jalisco, México : Prometeo Editores, 2010 páginas 154-154 ISBN:978-607-8019-26-7
Bibliotecas: Villahermosa
Cerrar
SIBE Villahermosa
43567-20 (Disponible)
Disponibles para prestamo: 1
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Resumen en: Español |
Resumen en español

Se cuantificaron las pérdidas de suelo por erosión fluvial (2006-2008) en dos cauces ribereños con cobertura de Haematoxylum campechianum, Dalbergia brownei y Brachiaria mutica. Asimismo se estudió y describió el proceso germinativo y la morfología de plántulas de Annona glabra, Ceiba pentandra Pachira aquatica, Haematoxylum campechianum, Coccoloba barbadensis y Crataeva tapia, especies arbóreas nativas propias de los humedales del sureste de México y útiles para su restauración. La principal tendencia de las pérdidas de suelo por tipo de cobertura vegetal se dio en el orden H. campechianum>B. mutica>D. brownei. El mayor impacto erosivo en sitios con H. campechianum se relacionó con la textura arenosa de los suelos y el grado de perturbación de los sitios. Las pérdidas totales de suelo en parcelas con B. mutica al segundo año se pudo relacionar con la distribución superficial de las raíces de este pasto y con la actividad ganadera. En cuanto a la germinación de semillas, se sembraron 50 semillas por especie. Se realizó la caracterización morfológica y se elaboró una clave de plántulas con base en: 1) tipo de germinación 2) eje de la plántula y 3) elementos foliares. Se realizaron tratamientos pregerminativos para A. glabra y C. barbadensismediante escarificación mecánica. Con excepción de C. barbadensis (69%) se obtuvo una germinación mayor a 86%. Este trabajo, proporciona información básica acerca del a) proceso germinativo y morfología de plántulas, b) reconocimiento de especies en sus primeros estadios de desarrollo, c) genera bases para la planificación de actividades de protección de bordos ribereños con el uso de especies nativas.


9.
Artículo
Resumen en: Inglés |
Resumen en inglés

With the increasing global legal and illegal trade of waste electrical and electronic equipment (WEEE) comes an equally increasing concern that poor WEEE recycling techniques, particularly in developing countries, are generating more and more environmental pollution that affects both ecosystems and the people living within or near the main recycling areas. This review presents data found in the scientific and grey literature about concentrations of lead (Pb), polybrominated diphenylethers (PBDEs), polychlorinated dioxins and furans as well as polybrominated dioxins and furans (PCDD/Fs and PBDD/Fs) monitored in various environmental compartments in China and India, two countries where informal WEEE recycling plays an important economic role. The data are compared with known concentration thresholds and other pollution level standards to provide an indication of the seriousness of the pollution levels in the study sites selected and further to indicate the potential negative impact of these pollutants on the ecosystems and humans affected. The review highlights very high levels of Pb, PBDEs, PCDD/Fs and PBDD/Fs in air, bottom ash, dust, soil, water and sediments in WEEE recycling areas of the two countries. The concentration levels found sometimes exceed the reference values for the sites under investigation and pollution observed in other industrial or urban areas by several orders of magnitude.

These observations suggest a serious environmental and human health threat, which is backed up by other studies that have examined the impact of concentrations of these compounds in humans and other organisms. The risk to the population treating WEEE and to the surrounding environment increases with the lack of health and safety guidelines and improper recycling techniques such as dumping, dismantling, inappropriate shredding, burning and acid leaching. At a regional scale, the influence of pollutants generated by WEEE recycling sites is important due to the long-distance transport potential of some chemicals. Although the data presented are alarming, the situation could be improved relatively rapidly by the implementation of more benign recycling techniques and the development and enforcement of WEEE-related legislation at the national level, including prevention of unregulated WEEE exports from industrialised countries.


Resumen en: Inglés |
Resumen en inglés

We studied the effects of land-use and land-cover changes on physical and chemical properties of soil in tropical South-East Mexico. In the study area of about 5500 km2, the dominant land use is pastureland (Pa seasonal agriculture (TA), fruit plantations (FP), sugarcane, (SC) secondary (SF) and primary forest (PF) and other not specified land-use types (undefined). From 1988 to 2003 severe deforestation took place and pastureland increased by 179% while primary forest decreased to 17% of the initial area. Based on topographic and soil maps we selected 176 sampling sites covering the combinations of topography and soil type. In 2005, we took soil samples in each selected site from two soil depths (0–20 cm and 20–40 cm). We analyzed fertility parameters like pH, texture and contents of organic carbon, total nitrogen and available phosphorus. Furthermore, we measured soil resistance against penetration in layers of 5 cm down to a depth of 40 cm. We estimated land-use changes between 1988 and 2005 using digital land-use maps derived from satellite and aerial photography interpretation. We compared soil properties of different soil types, soils under different current land use and under the influence of land-cover changes. Gleysols, Vertisols, Regosols, Luvisols and Leptosols showed clay to clay loam texture, whereas Cambisols were characterized by sandy clay loam texture. All soil groups in the study region were slightly acidic with pH(KCl) values between 5.3 and 6.2. Furthermore, they neither showed significant differences in available P content nor in C/N ratio. However, the investigated soil associations displayed different organic carbon and total nitrogen contents in the upper 20 cm depth.

Soils under different current land use did not show any significant differences with respect to available phosphorus, organic carbon, total nitrogen and C/N ratio whereas the pH value was significantly higher under seasonal agriculture than under pasture. Land-use changes between 1988 and 2003 did not significantly influence the contents of available phosphorus and organic carbon or the C/N ratio. However, total nitrogen was significantly higher in soils which were changed from forest in 1988 to seasonal agriculture in 2003 (F-TA) than in soils changed from forest to pastureland (F-Pa) or from pasture to forestland (Pa-F). Furthermore, soils under land-use change F-TA were less acidic in both depths than soils under Pa-F, TA-Pa, or which remained pastureland over the whole time (Pa-Pa). Soils in pastureland were significantly more compacted in all layers than soils used for seasonal agriculture. Soils that were used for pastureland already in 1988 showed significantly higher compaction than most of the other soils. We conclude that land-use change in a period of 15 years did not lead to chemical soil degradation. However, permanent pastureland leads to a severe compaction of soils.