Seasonal and spatial distribution of stoneflies in the Chubut River (Patagonia, Argentina) |
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Authors: | María Laura Miserendino |
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Institution: | (1) Laboratorio de Investigaciones en Ecología y Sistemática Animal (LIESA), Universidad Nacional de la Patagonia, Sede Esquel, Sarmiento 849, 9200 Chubut, Esquel, Argentina |
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Abstract: | Longitudinal and seasonal distributions of Plecoptera species were examined along the Chubut River in the Patagonian Precordillera
and Plateau, Argentina. Chubut River (>1000 km) is the largest river in the area and the hydrological regime is modified in
the lower section by an artificial reservoir (Florentino Ameghino Dam). Quantitative samples were collected in 13 sites in
the higher, middle, and lower sections of the river basin. Sites were visited four times during 2004, and a total of nine
species and 5772 individuals were collected in the study. Plecoptera richness decreased dramatically from the headwaters to
the mouth of the river system. Two species, Antarctoperla michaelseni and Potamoperla myrmidon, were able to live below the impoundment but they were not abundant. Notoperlopsis femina and A. michaelseni abundances were higher in summer than in the other seasons, while Limnoperla jaffueli peaked in spring. Species–environmental relationships were examined using Canonical Correspondence Analysis and six independent
variables were identified as the major factors structuring stoneflies assemblages. First axis was highly related to environmental
variables reflecting the hydro-geological and land use gradients in the basin (conductivity, total suspended solids, periphyton
Chlorophyll a). Second axis was more related to variables that changed seasonally (wet width, water temperature and soluble reactive phosphate). |
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Keywords: | Patagonian rivers Plecoptera longitudinal gradient environmental relationships abundance dam |
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