Browsing by Autor "Mabel Maldonado"

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A New Species of Piranha (Serrasalmus, Serrasalmidae) from the Upper Madeira River System, Amazon Basin, Bolivia
(Pleiades Publishing, 2024) F. Gallo-Cardozo; Mabel Maldonado; M. Careaga; Fernando M. Carvajal‐Vallejos
A new species of piranha, in the genus Serrasalmus (Characiformes, Serrasalmidae), is described from tributaries of the upper Madeira River drainage (Bolivian Amazon Basin). This new species exhibits a similar caudal-fin color like that observed in S. hollandi, and review of the literature suggested that former studies have misidentified these two species. The new species can be diagnosed morphologically from other congeners, but genetic variation of the COI sequence data showed little difference (~1%) from similar, morphologically recognized species. Since Serrasalmus species are widespread and morphologically difficult to identify, a key for identifying Bolivian species of this genus is presented.
Behavioral Bioassay with a Local Tadpole ( Pleuroderma cinereum ) from River Rocha, Bolivia, in River Water Spiked with Chromium 6+
(Springer Science+Business Media, 2004) Luc Janssens de Bisthoven; Almut Gerhardt; Mabel Maldonado
Caracterización limnológica de lagunas en la llanura aluvial del río Ichilo, Cochabamba (Bolivia)
(1996) Mabel Maldonado; Edgar Goïtia; Francisca Acosta; Mirtha Cadima; Dylian Castellón
Se realizo la caracterizacion limnologica de 11 lagunas situadas en la llanura inundable del rio Ichilo (16´ 01´´ a 16´ 57´´ S – 64´ 36´´ a 64´ 53´´ W) ubicado en la amazonia boliviana. La caracterizacion se realizo en base a variables morfologicas, fisico – quimicas y biologicas; estas incluyeron la composicion y abundancia relativa del plancton, bentos, macrofilia e ictiofauna. Las variables fueron determinadas en cuatro periodos hidrologicos entre los anos 1994 y 1995. Las lagunas se mostraron similares a otros ambientes sudamericanos respecto a las caracteristicas de sus aguas y a la composicion de sus comunidades, asi como tambien respecto a las variaciones que estas experimentan en funcion al regimen hidrologico; sin embargo se pueden apreciar diferencias interesantes debido a su posicion en las cabeceras del sistema hidrologico amazonico y que se reflejan en variaciones ambientales un tanto mas pronunciadas que las de los grandes rios. Palabras clave: Lagunas de llanura inundable, Amazonia boliviana, limnologia tropical, Cochabamba, Bolivia
Contaminación y eutrofización en la cuenca del río Rocha (Cochabamba)
(1998) Mabel Maldonado; Paul Van Damme; José Alejandro Romero Rojas
Correspondencia entre unidades geofísicas-bioclimáticas y patrones espaciales en ecosistemas acuáticos de Bolivia
(2001) Mabel Maldonado; Edgar Goïtia
CORRESPONDENCE BETWEN GEOPHYSICAL - BIOCLIMATIC UNITS AND SPATIAL PATTERNS IN AQUATIC ECOSYSTEMS OF BOLIVIA Con el proposito de establecer la correspondencia entre unidades ambientales (geofisicas y bioclimaticas) con las caracteristicas fisicas, quimicas y biologicas de ambientes acuaticos en la zona meridional de Bolivia, se realizo una transeccion de oeste a este incluyendo una gran parte de la heterogeneidad climatica, geologica y fisiografica del pais. En esta transeccion se definieron unidades geofisicas en base a informacion cartografica geologica y fisiografica, y unidades bioclimaticas en base al sistema de clasificacion bioclimatica de Rivas Martinez. En cada unidad asi definida, se colectaron datos fisicos, quimicos y de vegetacion en ambientes loticos, estos datos fueron examinados en dos ciclos de analisis (nivel y 11) utilizando analisis de discriminancia y de agrupamiento. Se lograron establecer patrones de variacion espacial en los ambientes acuaticos en cuatro niveles en orden de jerarquia: fisiografico, geologico, bioclimatico y geomorfologico. Con estos elementos se complementan las propuestas de regionalizacion de ambientes acuaticos existentes para Bolivia. Palabras claves: regionalizacion, bioclima, ecosistemas acuaticos, patrones espaciales, Bolivia. ABSTRACT A west east transect was established in order to investigate the relationship between environmental units geophysical and bioclimatical and physical, chemical, and biological characteristics of aquatic environments in the meridional zone of Bolivia. This transect includes a major part of the physiographical, geological and bioclimatic heterogeneity of the country. Geophysical units were defined through geological and physiographical maps, while bioclimatic units were defined using the bioclimatic classification system of Rivas Martinez. Within each unit, physical, chemical and vegetation data were collected in lotic environments. Data were analyzed in two cycles (level and 11) using discriminant and cluster analysis. Patterns of spatial variation were established within the aquatic environments at tour hierarchical levels: physiographical, geological, bioclimatic, and geomorphological. With these elements, the current proposals for the regionalization of aquatic environments of Bolivia have been complemented. Keywords: Regionalization, bioclimate, aquatic ecosystems, spatial patterns, Bolivia.
Diel vertical migration of zooplankton in an Amazonian várzea lake (Laguna Bufeos, Bolivia)
(Taylor & Francis, 2006) Danny Rejas; Luc De Meester; Lena Ferrufino; Mabel Maldonado; F. Ollevier
We studied diel vertical migration (DVM) of a variety of zooplanktonic taxa. Our results fit the predictions of the predator avoidance hypothesis, with larger taxa performing normal migrations to avoid fish predation and smaller taxa performing reversed migrations, probably to avoid predation by Chaoborus. Cladocerans and adults of copepods displayed normal DVM, whereas cyclopoid copepodites did not migrate. Five rotifer taxa migrated in a normal pattern whereas four taxa migrated in a reverse pattern. Our results suggest that during the day microcrustaceans moved close to the bottom, while rotifers showed narrower migration amplitudes. Larvae of the invertebrate predator Chaoborus displayed strong normal DVM, and appeared to synchronize its life cycle with the lunar cycle, with mass emergence of adults around New Moon.
Diversity of Rotifera in Freshwaters of Bolivia: An Updated Checklist
(Multidisciplinary Digital Publishing Institute, 2024) Carla E. Fernández; Melina Campero; Francisca Acosta; Pablo Prado; Mabel Maldonado; Edgar Goïtia; Georgia Stamou; Εvangelia Μichaloudi; Carlos López
Biodiversity records are of great importance, especially in light of the biodiversity crisis. Here, we present a study on the diversity of rotifers in Bolivia based on an extensive investigation of the literature published so far. Through this approach and an analysis of samples from 207 water bodies of the country, we updated the checklist of reported species. This study revealed a total of 195 species of rotifers previously reported; we identified 153 species in our samples, with 84 of them being reported for the first time in Bolivia. Thus, a total of 279 species are known at present in this country. Our findings suggest that Bolivia has a rich and diverse rotifer community, with many species likely to be unique to the region.
Effects of natural and anthropogenic environmental changes on riverine fish assemblages: a framework for ecological assessment of rivers
(Instituto de Tecnologia do Paraná (Tecpar), 2005) Francisco Leonardo Tejerina‐Garro; Mabel Maldonado; Carla Ibañez; Didier Pont; Nicolas Roset; Thierry Oberdorff
Freshwater is a basic need for the mankind. Effective biological tools (ecologically based, efficient, rapid and consistently applicable to different ecological regions) are needed to measure the "health" of rivers. Adapting such tools over a broad geographic area requires a detailed understanding of both the patterns of organisms assemblage composition and distribution within and among water bodies under natural conditions, and the nature of the major environmental gradients that cause or explain these patterns. A comprehensive review of the available litterature dealing with the identification of environmental factors structuring riverine fish assemblages under natural conditions permits to identify the most consistent ones.
Estructura trófica de la ictiocenosis en lagunas de la llanura inundable de los ríos Ichilo y Chapare, (Bolivia)
(2000) Guido Ayala; Karina Zambrana; Mabel Maldonado
TROPHIC STRUCTURE OF THE ICHTHYOCOENOSIS IN SHALLOW LAKES OF THE FLOODPLAIN OF THE ICHILO AND CHAPARE RIVERS (BOLIVIA) Se estudio la estructura trofica de la ictiofauna de cuatro lagunas de la varzea de los rios Ichilo y Chapare (Departamentos de Cochabamba y Santa Cruz; 16005' a 16°43'S y 64°48' a 64°72'W) mediante el analisis estomacal de 1111 ejemplares pertenecientes a 52 especies y capturados en cuatro fases hidrologicas de los anos 1994 y 1995. Se utilizo un indice alimentario para agrupar las especies, definiendose cuatro grandes categorias troficas: carnivoros, herbivoros, omnivoros y detritivoros. Los grupos mas variados en numero de especies fueron los omnivoros y carnivoros, en tanto que en numero de individuos fueron dominantes los carnivoros que representaron algo mas del 50% de la abundancia total, les siguieron los omnivoros y los detritivoros, siendo los menos abundantes los herbivoros. El analisis temporal y espacial de la estructura trofica mostro que las variaciones entre lagunas son poco notorias, mostrandose mas importantes las variaciones entre fases hidrologicas, que basicamente implican un aumento en la proporcion de herbivoros durante la fase de inundacion. Se presenta una red trofica para las lagunas, que tampoco mostro variaciones importantes ni entre lagunas ni entre fases hidrologicas. Estos resultados sugieren que la estructura trofica de estas lagunas seria diferente a las descritas para grandes rios de la Amazonia y de otras cuencas sudamericanas, debido a una menor importancia de las especies detritivoras, herbivoras y omnivoras frente a las carnivoras, ya una relativa estabilidad de la estructura frente a los cambios hidrologicos asociados a un pulso de inundacion corto y poco predecible. Palabras claves: Estructura trofica, redes troficas, peces, rio Ichilo, rio Chapare, lagunas de varzea, llanuras inundables, Bolivia. ABSTRACT The trophic structures of fish communities in tour Varzea lakes of the Ichilo and Chapare Rivers States of Cochabamba and Santa Cruz; 1605'16°43' S and 64°48'64°72'W) were studied during tour hydrologic seasons in 1994 and 1995 by means of stomach content analysis of 1 111 individuals, pertaining to 52 species. The alimentary index was used to group the species in the tour trophic categories of carnivores, herbivores, omnivores, and detritovores. The most diverse groups, in terms of species number; were the omnivores and carnivores. In terms of number of individuals, the carnivores where dominant, representing more than 50% of the total. Omnivores and detritovores were less common with herbivores being least abundant. Temporal and spatial analysis of the trophic structure showed that the differences between lakes were small, while variations between hydrological seasons were more important. This variation resulted in an increase in herbivores during the high-water season. Trophic webs for the lakes were developed. No important variations between lakes or between hydrologic seasons were observed. In sum due to the lesser importance of detritivores, herbivores, and omnivores compared to carnivores and due to a more stable structure with respect to hydrologic changes, the trophic structure of these lakes seems to be different from those described for large Amazon rivers or other similar south American river systems, such as the Orinoco and Parana river systems. Key Words: Trophic structure, trophic webs, fish, Ichilo River Chapare River, Varzea, lakes, floodplain, Bolivia.
Las hidroecorregiones del departamento de Cochabamba
(2003) Mabel Maldonado; Edgar Goïtia
Local-scale species–energy relationships in fish assemblages of some forested streams of the Bolivian Amazon
(Elsevier BV, 2007) Pablo A. Tedesco; Carla Ibañez; Nabor Moya; Rémy Bigorne; Jimena Camacho; Edgar Goïtia; Bernard Hugueny; Mabel Maldonado; Mirtha Rivero; Sylvie Tomanová
Productivity (trophic energy) is one of the most important factors promoting variation in species richness. A variety of species–energy relationships have been reported, including monotonically positive, monotonically negative, or unimodal (i.e. hump-shaped). The exact form of the relationship seems to depend, among other things, on the spatial scale involved. However, the mechanisms behind these patterns are still largely unresolved, although many hypotheses have been suggested. Here we report a case of local-scale positive species–energy relationship. Using 14 local fish assemblages in tropical forested headwater streams (Bolivia), and after controlling for major local abiotic factors usually acting on assemblage richness and structure, we show that rising energy availability through leaf litter decomposition rates allows trophically specialized species to maintain viable populations and thereby to increase assemblage species richness. By deriving predictions from three popular mechanistic explanations, i.e. the ‘increased population size’, the ‘consumer pressure’, and the ‘specialization’ hypotheses, our data provide only equivocal support for the latter.
Patrones espaciales de la comunidad planctónica lacustre en un gradiente geofísico y bioclimático en Bolivia
(Elsevier BV, 2003) Francisca Acosta; Mirtha Cadima; Mabel Maldonado
The 5-enolpyruvylshikimate-3-phosphate synthase catalyses the sixth step of the shikimate pathway that is responsible for synthesizing aromatic compounds and is absent in mammals, which makes it a potential target for drugs development against microbial diseases. Here, we report the phosphate binding effects at the structure of the 5-enolpyruvylshikimate-3-phosphate synthase from Mycobacterium tuberculosis. This enzyme is formed by two similar domains that close on each other induced by ligand binding, showing the occurrence of a large conformation change. We have monitored the phosphate binding effects using analytical ultracentrifugation, small angle X-ray scattering and, circular dichroism techniques. The low resolution results showed that the enzyme in the presence of phosphate clearly presented a more compact structure. Thermal-induced unfolding experiments followed by circular dichroism suggested that phosphate rigidified the enzyme. Summarizing, these data suggested that the phosphate itself is able to induce conformational change resulting in the closure movement in the M. tuberculosis 5-enolpyruvylshikimate-3-phosphate synthase.
Population dynamics of two Andean Trichomycterus (Siluriformes: Trichomycteridae) species from Bolivia
(Sociedade Brasileira de Ictiologia, 2025) F. Gallo-Cardozo; Fernando M. Carvajal‐Vallejos; M. Careaga; Laura Herbas; Edgar Goïtia; Mabel Maldonado
Abstract The species of Trichomycterus (Siluriformes: Trichomycteridae) are small catfish distributed throughout South and Central America, from Patagonia to Costa Rica, at elevations ranging from sea level to over 4,000 m. In Bolivia, 17 species have been recorded, but information about the status of their populations and their relationship with the environment is unknown. This study addressed the population dynamics of two species (T. cf. corduvensis and T. tiraquae) in an Andean river from the Cochabamba Department in Bolivia, over a hydrological cycle. Monthly abundance, size structure, condition factor (K), and the relationship between abundance and environmental factors were calculated using multiple regressions. Results indicated that T. cf. corduvensis is more abundant than T. tiraquae. The temporal variation in the abundance of both species is related to the hydrological cycle and local factors, without showing a clear habitat preference. Juvenile individuals predominate, and the condition factor did not vary significantly.
The combined effects of climate change and river fragmentation on the distribution of Andean Amazon fishes
(Wiley, 2020) Guido A. Herrera‐R; Thierry Oberdorff; Elizabeth P. Anderson; Sébastien Brosse; Fernando M. Carvajal‐Vallejos; Renata G. Frederico; Max Hidalgo; Céline Jezequel; Mabel Maldonado; Javier A. Maldonado‐Ocampo
Upstream range shifts of freshwater fishes have been documented in recent years due to ongoing climate change. River fragmentation by dams, presenting physical barriers, can limit the climatically induced spatial redistribution of fishes. Andean freshwater ecosystems in the Neotropical region are expected to be highly affected by these future disturbances. However, proper evaluations are still missing. Combining species distribution models and functional traits of Andean Amazon fishes, coupled with dam locations and climatic projections (2070s), we (a) evaluated the potential impacts of future climate on species ranges, (b) investigated the combined impact of river fragmentation and climate change and (c) tested the relationships between these impacts and species functional traits. Results show that climate change will induce range contraction for most of the Andean Amazon fish species, particularly those inhabiting highlands. Dams are not predicted to greatly limit future range shifts for most species (i.e., the Barrier effect). However, some of these barriers should prevent upstream shifts for a considerable number of species, reducing future potential diversity in some basins. River fragmentation is predicted to act jointly with climate change in promoting a considerable decrease in the probability of species to persist in the long-term because of splitting species ranges in smaller fragments (i.e., the Isolation effect). Benthic and fast-flowing water adapted species with hydrodynamic bodies are significantly associated with severe range contractions from climate change.
Variaciones espacio-temporales de la composición de la comunidad de peces de una laguna de la várzea del río Ichilo (Cochabamba, Bolivia)
(2000) Danny Rejas; Mabel Maldonado
SPATIAL-TEMPORAL VARIATIONS IN THE COMPOSITION OF THE FISH COMMUNITY OF A SHALLOW LAKE IN THE FLOODPLALN OF THE ICHILO RIVER COCHABAMBA, BOLIVIA) El presente trabajo se realizo con el objetivo de describir las variaciones estructurales de la ictiocenosis en dos habitat diferentes y en dos epocas hidrologicas extremas. El estudio se llevo a cabo en la laguna Bufeos ubicada en la planicie de inundacion del rio Ichilo a 16.4SOS y 64. 700.Se capturaron 35 especies, distribuidas en 14 familias y cuatro ordenes. La familia Characidae fue la representada por un mayor numero de especies y la familia Curimatidae fue la mas abundante en numero de individuos y biomasa.La estructura de la comunidad presento variaciones espacio-temporales, tanto en diversidad como en rendimiento. Se encontro un mayor rendimiento de pesca en epoca de aguas bajas, sin embargo la riqueza especifica y la diversidad se incrementaron despues de la inundacion.En conjunto la estructura biocenotica muestra cambios de poca magnitud en relacion a otros ambientes similares donde el pulso de inundacion es mas prolongado y predecible que en el rio Ichilo. Palabras clave: Ictiocenosis, laguna, varzea, variaciones espacio-temporales. Bolivia. ABSTRACT The objective of this study was to describe the variations in the ichthyocoenosis structure in two different habitats and the two extreme of the hydrologic cycle. The field work was done in the Bufeos Laguna, a shallow lake in the floodplain of the Ichilo River (16. 43 oS y 64.70°W).During the study, 35 species, distributed in 14 families and tour orders, were obtained. The Characidae family was most abundant with respect to species numbet; while, the Curimatidae family was the most abundant, both in number of individuals and biomass. The community structure showed spatial-temporal variations, both in diversity and in yield. The catch increased during the low-water season. However species richness and diversity increased after flooding.The overall biocenotic structure showed only slight variations in comparison with similar environments where the flooding is longer and more predictable than in the Ichilo River. Key Words: Ichthyocoenosis, shal!ow lake, floodplain, spatial-temporal variations, Bolivia.