Abstract:The river zonation hypothesis predicts that abiotic and biotic conditions along riparian gradients drive variation in animal communities. Glass frogs are a diverse group of Neotropical anurans that use riparian habitats exclusively for oviposition and larval development, but little is known about how glass frog communities are distributed across riparian gradients. Here, we measured glass frog community assembly across a gradient of riparian habitats from first- to fifth-order streams at La Selva Biological Station, Costa Rica. We performed repeated nocturnal frog calling surveys and built occupancy andN-mixture abundance models to test for varying patterns of species occupancy, community assembly, species richness (α-diversity) and species turnover (ß-diversity). We observed significant differences in patterns of species occupancy and community assembly across a stream-order gradient: occupancy of two species increased with stream order (Teratohyla pulverata,Hyalinobatrachium fleischmanni), one species decreased (Teratohyla spinosa), and one species did not vary (Espadarana prosoblepon). We evaluated four a priori hypotheses describing how α- and ß-diversity of centrolenids are shaped across the riparian gradient; our data were most consistent with a pattern of nested assemblages and increasing species richness along the riparian gradient. Species-specific patterns of occupancy and abundance resulted in assemblage-level differences consistent with theoretical predictions for highly aquatic organisms along riparian gradients.
ResumenEn este trabajo se establece la calidad de agua del curso superior y medio del río Traiguén ubicado en la IX Región de la Araucanía en Chile. La caracterización fisicoquímica y microbiológica se efectuó fijando seis estaciones de muestreo, desde un lugar cercano a la naciente del río hasta el límite comunal de la ciudad de Victoria con Traiguén. Los valores mas bajos en los parámetros evaluados, los presentan las aguas de las estaciones 1 y 2 ubicadas fuera del límite urbano, contrariamente a lo que ocurre con las estaciones 3, 4 y 5 que muestran los efectos de los afluentes: planta lácteos, curtiembre y aguas servidas respectivamente. Los resultados de la parte microbiológica señalan que las aguas de ninguna de las estaciones del río pueden emplearse como fuente de abastecimiento para consumo humano por estar sobre los límites fijados por la norma chilena (NCh 409, 1984). Se presentan limitaciones en sus comunidades así como para su uso en regadío, y recreación con contacto directo.
Palabras clave: calidad de agua, caracterización fisicoquímica y microbiológica, estaciones de muestreo, medioambiente
Superior and Medium Water Quality in Traiguén River. IX Region-Chile AbstractThe water quality in the upper and medium zone of Traiguén river in the Araucanía region was studied in the present work. Physico-chemical and microbiological parameters were measured at six sample stations in a zone that goes from close to the origin of the river to the limits of the city of Victoria with Traiguén. The influence of the Victoria town on the water quality of Traiguen river generates as consequence low values of studied parameters that were reported in sampling stations 1 and 2 located in the surrounding of Victoria town. A different situation was reported in stations 3, 4 and 5, that show the effects of waste dispose by milky industries, leather industries and waste water respectively. The results of microbiological parameters denoted that the water of all sampled stations can not be used for human use because the parameters are upper than regulations. Also, limitations were denoted in their ecological parameters, and for their use in irrigating and recreational activities.
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