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4 resultados encontrados para: AUTOR: Pease, Allison A
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1.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

Assessments of trophic diversity are critical for evaluating ecological integrity of habitats, but interpretations of such assessments require an understanding of variation across natural environmental gradients. This can be problematic when comparing structure of assemblages in under-studied regions or habitats, such as watersheds in dry tropical forests. Here,we compared assemblage-wide trophic metrics and intraspecific variation for a subset of consumer traits across rivers and among different ecosystem types within the Grijalva and Usumacinta River basins of Mexico. The two rivers differ with respect to flow-regime alteration and climate: the Grijalva River has been hydrologically altered by a series of dams and has wet and dry tropical forests in its watershed, whereas the Usumacinta River remains unimpounded with a watershed dominated by tropical wet forest. Use of allochthonous resourceswas pervasive in Usumacinta basin tributaries,with stable isotope signatures suggesting that many fishes directly consumed riparian plants and detritus. In contrast, fish assemblages inGrijalva basin tributaries were supported by higher proportions of in-stream production. Food-chain length was highest in a Grijalva River reservoir fish assemblage, although trophic diversity was lowin the impounded systemcompared to the mainstem Usumacinta River, where fishes consumed the broadest variety of food resources. We also observed differences in trophic ecology and body nutrient content within taxa across habitat types and basins. The differences we observed suggest that even in relatively intact watersheds, expectations for trophic structure in tropical streams should be adjusted based on factors such as discharge, climate, and riparian forest cover.


2.
Artículo
*Solicítelo con su bibliotecario/a
Feeding ecology and ecomorphology of cichlid assemblages in a large Mesoamerican river delta
Pease, Allison A. ; Mendoza Carranza, Manuel (coaut.) ; Winemiller, Kirk O. ;
Contenido en: Environmental Biology of Fishes Vol. 101, no. 6 (June 2018), p. 867–879 ISSN: 0378-1909
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Fish assemblages in tropical lowland rivers are characterized by a high richness of species that feed on a diverse array of food resources. Although closely related species often have similar feeding ecology, species within the family Cichlidae display a broad spectrum of trophic niches, and resource partitioning has been inferred from studies conducted in Neotropical rivers. We investigated interspecific variation in food resource use and its relationship to morphological variation among cichlid fishes within the Pantanos de Centla Biosphere Reserve, a coastal area encompassing the delta of the Grijalva-Usumacinta River in Tabasco, Mexico. Most species consumed benthic crustaceans, aquatic insect larvae, and detritus, but some were more herbivorous, and one species was a specialized piscivore. Dietary niche overlap among species was higher than expected for one assemblage, and similar to random expectations for another, suggesting a lesser role for resource partitioning than has been shown for some cichlid assemblages, perhaps due to availability of abundant resources, even in low-water conditions. Canonical correspondence analysis revealed that greatest morphological differences am7ong species involved functional traits directly associated with resource use. Relationships between feeding ecology and morphology were similar to those described for other riverine cichlids. Strong ecomorphological relationships facilitate inferences about the ecology of cichlid species, including species that currently lack data from field studies. Knowledge of ecological relationships will be important for conservation in the Pantanos de Centla, an ecosystem of global significance for biodiversity and ecosystem services.


3.
Artículo - Nota científica con arbitraje
*Solicítelo con su bibliotecario/a
Tourism, wastewater, and freshwater conservation in Palenque National Park, Mexico
Capps, Krista A. ; Castillo Uzcanga, María Mercedes (coaut.) ; Pease, Allison A. (coaut.) ; Jarquín Sánchez, Aarón (coaut.) ; Rodiles Hernández, María del Rocío (coaut.) (1956-) ;
Contenido en: The Southwestern Naturalist Vol. 62, no. 3 (November 2017), p. 220-225 ISSN: 0038-4909
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Resumen en español

A medida que las densidades de población humana crecen alrededor de las fronteras de las áreas protegidas en las economías de bajos ingresos, con frecuencia hay aumentos con comitantes en la degradación ambiental. El propósito de este estudio fue examinar la química del agua y las firmas isotópicas de los consumidores primarios en arroyos dentro y alrededor de un parque nacional en los trópicos para documentar si las cuencas del parque fueron impactadas por aguas residuales no tratadas. Tres de los seis sitios de estudio tenían concentraciones de fósforo reactivo soluble > 39 µg/L. Además, hubo una fuerte correlación positiva entre los valores de δN15 de los caracoles de pastoreo y las concentraciones de fósforo del agua, lo que sugiere que el efluente de las aguas residuales está influyendo en la ecología trófica en los hábitats acuáticos protegidos. Los resultados de este estudio dan apoyo a las recientes convocatorias de gestión más allá de los topes ribereños para la conservación de la integridad del ecosistema de agua dulce en áreas protegidas.

Resumen en inglés

As human population densities grow around the boundaries of protected areas in lower-income economies, there are frequently concomitant increases in environmental degradation. The purpose of this study was to examine water chemistry and the isotopic signatures of primary consumers in streams in and around a national park in the tropics to document whether park watersheds were affected by untreated wastewater. Three of the six study sites had concentrations of soluble reactive phosphorus >39 µg/L. Additionally, there was a strong, positive correlation between δN15 values of grazing snails and phosphorus concentrations of the water, suggesting that sewage effluent is influencing trophic ecology in the protected aquatic habitats. The results from this study lend support to recent calls for management beyond riparian buffers for conservation of freshwater ecosystem integrity in protected areas.


4.
- Artículo con arbitraje
Functional diversity and trait–environment relationships of stream fish assemblages in a large tropical catchment
Pease, Allison A. ; González Díaz, Alfonso Ángel (coaut.) ; Rodiles Hernández, María del Rocío (coaut.) (1956-) ; Winemiller, Kirk O. (coaut.) ;
Contenido en: Freshwater Biology Vol. 57, no. 5 (May 2012), p. 1060–1075 ISSN: 0046-5070
Resumen en: Inglés |
Resumen en inglés

1. The species composition of stream fish assemblages changes across the longitudinal fluvial gradient of large river basins. These changes may reflect both zonation in species distributions and environmental filtering of fish traits as stream environments change from the uplands to the lowlands of large catchments. Previous research has shown that taxonomic diversity generally increases in larger, lowland streams, and the River Continuum Concept, the River Habitat Template and other frameworks have provided expectations for what functional groups of fishes should predominate in certain stream types. However, studies addressing the functional trait composition of fish assemblages across large regions are lacking, particularly in tropical river basins. 2. We examined functional trait–environment relationships and functional diversity of stream fish assemblages in the Río Grijalva Basin in southern Mexico. Traits linked to feeding, locomotion and life history strategy were measured in fishes from streams throughout the catchment, from highland headwaters to broad, lowland streams. Relationships between functional traits and environmental variables at local and landscape scales were examined using multivariate ordination, and the convex hull volume of trait space occupied by fish assemblages was calculated as a measure of functional diversity. 3. Although there were a few exceptions, functional diversity of assemblages increased with species richness along the gradient from uplands to lowlands within the Grijalva Basin. Traits related to swimming, habitat preference and food resource use were associated with both local (e.g. substratum type, pool availability) and landscape-scale (e.g. forest cover) environmental variables.

4. Along with taxonomic structure and diversity, the functional composition of fish assemblages changed across the longitudinal fluvial gradient of the basin. Trait–environment relationships documented in this study partially confirmed theoretical expectations and revealed patterns that may help in developing a better understanding of general functional responses of fish assemblages to environmental change.