Abstract:In floodplain communities, beta diversity is influenced by different factors; however, environmental heterogeneity and floods are believed to be particularly influential. The influence of environmental heterogeneity and floods on beta diversity may vary among guilds that present different ecological traits. This study evaluated the correlation between the environmental heterogeneity and flood periods and the beta diversity of trophic and reproductive guilds of fish assemblages. Sampling was conducted quarterly… Show more
“…The annual flood pulse promotes fish dispersal, frequent restructuring of fish assemblages over variable spatial scales, homogenization of assemblage composition, and a decline in β diversity. Gutiérrez et al () evaluated the effects of environmental heterogeneity and floods on fish β diversity in a floodplain reach of the Upper Paraná River and found that for species with high dispersal capabilities, there was no clear relation between the flood pulse, environmental heterogeneity, and β diversity. Only those fishes with limited dispersal rates, especially substrate‐nesting species with brood care, revealed patterns associated with hydrological and environmental variation.…”
Citation: L opez-Delgado, E. O., K. O. Winemiller, and F. A. Villa-Navarro. 2020. Local environmental factors influence beta-diversity patterns of tropical fish assemblages more than spatial factors. Ecology 101(2):Abstract. A major goal in ecology is to understand mechanisms that influence patterns of biodiversity and community assembly at various spatial and temporal scales. Understanding how community composition is created and maintained also is critical for natural resource management and biological conservation. In this study, we investigated environmental and spatial factors influencing beta diversity of local fish assemblages along the longitudinal gradient of a nearly pristine Neotropical river in the Colombian Llanos. Standardized surveys were conducted during the low-water season at 34 sites within the Bita River Basin. Physical, chemical, and landscape parameters were recorded at each site, and asymmetric eigenvector maps were used as spatial variables. To examine the relative influence of dispersal and environmental variables on beta diversity and its components, distance-based redundancy analysis (db-RDA) and variation partitioning analysis were conducted. We proposed that spatial scale of analysis and position within the river network would constrain patterns of beta diversity in different ways. However, results indicated that in this system, high beta diversity was consistent among species assemblages no matter the scale of analysis or position within the river network. Species replacement (turnover) dominated beta diversity, an indication of the importance of species sorting. These findings suggested that conservation of fish diversity in tropical rivers requires maintenance of both habitat heterogeneity (spatial variation in habitat conditions) and connectivity at the scale of entire river basins.
“…The annual flood pulse promotes fish dispersal, frequent restructuring of fish assemblages over variable spatial scales, homogenization of assemblage composition, and a decline in β diversity. Gutiérrez et al () evaluated the effects of environmental heterogeneity and floods on fish β diversity in a floodplain reach of the Upper Paraná River and found that for species with high dispersal capabilities, there was no clear relation between the flood pulse, environmental heterogeneity, and β diversity. Only those fishes with limited dispersal rates, especially substrate‐nesting species with brood care, revealed patterns associated with hydrological and environmental variation.…”
Citation: L opez-Delgado, E. O., K. O. Winemiller, and F. A. Villa-Navarro. 2020. Local environmental factors influence beta-diversity patterns of tropical fish assemblages more than spatial factors. Ecology 101(2):Abstract. A major goal in ecology is to understand mechanisms that influence patterns of biodiversity and community assembly at various spatial and temporal scales. Understanding how community composition is created and maintained also is critical for natural resource management and biological conservation. In this study, we investigated environmental and spatial factors influencing beta diversity of local fish assemblages along the longitudinal gradient of a nearly pristine Neotropical river in the Colombian Llanos. Standardized surveys were conducted during the low-water season at 34 sites within the Bita River Basin. Physical, chemical, and landscape parameters were recorded at each site, and asymmetric eigenvector maps were used as spatial variables. To examine the relative influence of dispersal and environmental variables on beta diversity and its components, distance-based redundancy analysis (db-RDA) and variation partitioning analysis were conducted. We proposed that spatial scale of analysis and position within the river network would constrain patterns of beta diversity in different ways. However, results indicated that in this system, high beta diversity was consistent among species assemblages no matter the scale of analysis or position within the river network. Species replacement (turnover) dominated beta diversity, an indication of the importance of species sorting. These findings suggested that conservation of fish diversity in tropical rivers requires maintenance of both habitat heterogeneity (spatial variation in habitat conditions) and connectivity at the scale of entire river basins.
“…The conversion of forest to pasture is also expected to have a negative impact on species with specific functional traits, such as parental care, benthic habits, and invertivorous or piscivorous diets (Casatti et al., 2012). Parental care, for example, may depend on the availability of allochthonous debris to provide shelter and is typical of species with a reduced dispersal capacity (Gutiérrez et al., 2018). The reduced heterogeneity in the substrate of the streambed may also be unfavourable to benthic species (Teresa et al., 2015), while many insect and fish prey may disappear due to the absence of riparian vegetation (Woodward & Hildrew, 2002).…”
In recent years, increasing economic development has resulted in high rates of change in land use which have a negative impact on both terrestrial and aquatic habitats (Newbold et al., 2018). In the Amazon region, many studies have demonstrated that these changes in land use have resulted in a decrease in the basal area of the forest, changes in the physical-chemical characteristics of the water, such as its temperature and pH, the loss of riparian vegetation and impacts on the associated fauna (Luiza-Andrade et al., 2017;Mendes-Oliveira et al., 2017;Prudente et al., 2017). Nepstad et al. (2008) found that approximately 20% of the forest in the Amazon region has already been transformed
“…Asimismo, la secuencia hidrológica producto de los pulsos de inundación (Junk, et al, 1989) somete a las comunidades ícticas a sucesiones ecológicas regulares y repetidas y establece relaciones recíprocas entre las corrientes de agua y los cuerpos lénticos (Lewis, et al, 2000;Bozelli, et al, 2015). En consecuencia, estas comunidades logran dispersarse en todos los ambientes acuáticos disponibles a medida que los ecosistemas fluctúan (Lacambra & Pinilla, 2004;Gutiérrez, et al, 2018).…”
Las sabanas inundables son un bioma importante para la diversidad y funcionalidad de lascomunidades ícticas del Orinoco. Estas sabanas tienen gran conectividad y diversidad ecosistémica,incluida la conformación de diferentes tipos de humedales, por lo que comprender la forma en quesus comunidades de peces se estructuran en los diversos ambientes es clave para la conservaciónbiológica. El objetivo de este estudio fue determinar la diversidad, la composición y la estructura delos ensamblajes ícticos en los humedales, caños del sistema río-planicie de inundación y esteros delsistema periférico en la sabana inundable del río Ariporo (Casanare). Para ello se analizaron sietesitios distribuidos en ambos tipos de humedales muestreados durante dos periodos hidrométricos enaguas en descenso y aguas bajas. Los peces se recolectaron utilizando una red de arrastre de 10 mx 1,5 m y ojo de malla de 2 mm. La estructura y diversidad de los ensamblajes ícticos se analizaronmediante los modelos de distribución-abundancia, los números de Hill, el análisis de escalamientomultidimensional no-métrico (EMNM) y el índice de especies indicadoras (IndVal). Los resultadosindicaron que los caños albergan la mayor riqueza y diversidad de especies. Asimismo, el EMNM(stress=0,00009) evidenció la conformación de dos ensamblajes ícticos según el tipo de humedal. Enel ensamblaje íctico de caños, se registraron especies especialistas como indicadoras a diferencia delos esteros. Se sugiere que los caños albergan comunidades más complejas y diversas, en tanto quelos esteros son dominados por especies generalistas.
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