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An ordination of the River Cadagua basin has been made using trichopteran taxa as entities. Differences between headwater reaches and lower parts of the main river and its principal tributaries are chiefly based on the downstream substitution of the species of the genus Rhyacophila by species of the genus Hydropsyche. On the plane of the first two axes from a correspondence analysis, the first station of the River Cadagua appears to be separated from the other headwater sites due to the presence of a trichopteran assemblage being only at this place and composed of Rhyacophila tristis, Lype reducta and Tinodes assimilis. Sympatric species of the genera Rhyacophila and Hydropsyche coexisted at several places, although appearing alone at other sites and showing differential preferences for the highest or lowest sites. Thus, Hydropsyche pellucidula coexisted with Hydropsyche siltalai in the middle section of the rivers, but the former was distributed further downstream than the latter which, by contrast, occupied higher reaches.Among sites, differences in trichopteran assemblage structure are a result of both natural and antropogenic changes in the physico-chemical features of the water courses. Thus trichopteran diversity and coexistence of sympatric species increase downstream with increasing nutrient values, if the oxygen content of the water is near saturation level. However, Trichoptera disappear from sites with low oxygen content. Conductivity values do not seem to affect trichopteran distribution in natural waters, as values higher than 700 S cm were found at the headwater of the main river containing an assemblage characteristic of these sites. 相似文献
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San Martin David Orive Mikel Martínez Ekaitz Iñarra Bruno Ramos Saioa González Nagore Guinea de Salas Alejandro Vázquez Luis Alberto Zufía Jaime 《Environmental science and pollution research international》2021,28(13):15716-15730
Environmental Science and Pollution Research - Approximately 33% of food produced around the world is wasted. In the distribution sector, erroneous orders or demand predictions result in products... 相似文献
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