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Composition and diversity of Ephemeroptera (Insecta) nymph communities in the middle section of the Jacui River and some tributaries, southern Brazil

SIEGLOCH, Ana Emilia; FROEHLICH, Claudio Gilberto; KOTZIAN, Carla B.
Fonte: FUNDACAO ZOOBOTANICA RIO GRANDE SUL, MUSEU CIENCIAS NATURAIS Publicador: FUNDACAO ZOOBOTANICA RIO GRANDE SUL, MUSEU CIENCIAS NATURAIS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.95%
The taxonomic composition and diversity of assemblages of Ephemeroptera nymphs of four lotic environments in the central region of State of Rio Grande do Sul, a subtropical area in southern Brazil, were evaluated. Samplings were done monthly, with a Surber sampler, from June 2001 to May 2002, in the Jacui River and three of its tributaries. The total number of nymphs collected in the four sampling sites was 11,007 in five families and 19 genera, of these, 11 are new records for the State. The highest diversity occurred in Point 4 (H` = 2.41) and the lowest in Point 2 (H` = 1.69). Point 4 had the highest environmental stability, conservation of the riparian vegetation and the lowest anthropic impact, while Point 2 presented a large environmental simplification due to a direct anthropic influence ( e. g. domestic sewerage, trampling by cattle). The diversity of nymphs observed in the total area is high, compared to the estimated maximum theoretical diversity; a result of the high evenness and richness recorded. Rarefaction curves, calculated for a sample of 1,018 specimens, showed a similar expectation of richness for the four sampling sites. This result seems to be associated with the overall environmental homogeneity of the region caused by long-term alterations ( land use and deforestation). In summary...