Com este trabalho, objetivou-se investigar as espécies pertencentes às famílias Desmidiaceae, Gonatozygaceae e Mesotaeniaceae na comunidade perifítica de um reservatório, localizado no Sul do Brasil. As amostras foram coletadas durante os períodos de verão e inverno em distintas regiões ao longo do eixo rio-barragem do reservatório. Os substratos, coletados sempre na região litorânea, foram pecíolos de vegetação aquática. Foram identificados 45 táxons, distribuídos nos gêneros Actinotaenium (1 espécie), Cosmarium (17), Cylindrocystis (1), Euastrum (3), Gonatozygon (1),Hyalotheca (1), Micrasterias (7), Netrium (1), Pleurotaenium (1), Spondylosium (1), Staurastrum (9) e Staurodesmus (2). Maior riqueza de espécies ocorreu na região de transição para ambos os períodos de coleta. Euastrum denticulatum Gay e Hyalotheca dissiliens (Smith) Brébisson ex Ralfs apresentaram 100% de ocorrência, enquanto Cosmarium abbreviatum Raciborski var. minus (West & West) Krieger & Gerloff e Pleurotaenium ehrenbergii (Brébisson) De Bary ocorreram em 83% das amostras.
-(Influence of the longitudinal gradient (river-dam) in the silimarity of the communities of the periphytic desmids). The aim of this work was to evaluate periphytic desmids composition in the distinct regions to long of the axis the river-dam and the main biotic and abiotic factors that had affected the composition of this set in the Rosana (Paranapanema River) and "Salto do Vau" Reservoirs (Iguaçu River). The samples were collected in the summer and winter periods, during 2002. The substrata collected was petioles of the aquatic vegetation, in the adult stadium. In the results were registered 531 species and of these 191 are species of desmids, with 171 registered in the summer and 113 in the winter period. Of the 18 genera of desmids, Cosmarium Corda was most representative (34.2%) in Rosana and Closterium Nitzch ex Ralfs (30.8%) in "Salto do Vau" Reservoirs. Cluster analysis with all the showed species of desmids, sites and periods separated to both reservoirs, being that the periods were clearly evidenced only for the "Salto do Vau" Reservoir. The composition of the desmids in the three regions of Rosana varied in the two periods. Already in "Salto do Vau" the greatest richness occurred in the transition region.Key words -aquatic macrophytes, periphytic desmids, periphyton, reservoirs Palavras-chave -desmídias perifíticas, macrófitas aquáticas, perifíton, reservatórios RESUMO -(Influência do gradiente longitudinal (rio-barragem) na similaridade das comunidades de desmídias perifíticas
Periphytic algal community in artificial and natural substratum in a tributary of the Rosana reservoir (Corvo Stream, Paraná State, Brazil). This study evaluated the heterogeneity in periphytic algal community, under the influence of time colonization on artificial substratum. We also examined which abiotic variables most influenced the community in natural and artificial substratum. Egeria najas Planchon was used as natural substratum, and a plastic plant, as artificial. This experiment was carried out in a lateral arm from Rosana Reservoir, formed by Corvo Stream (Paranapanema river basin), in the period from November 21 st to December 12 nd , 2003, characterized as a warm and rainy period. Changes in species composition were assessed using the similarity indices. 495 taxa were registered in the phycoperiphytic community, distributed in 133 genera and 11 classes. Zygnemaphyceae, Bacillariophyceae, Chlorophyceae and Cyanophyceae presented higher species number, in both substrata. Staurodesmus, Closterium, Staurastrum and Cosmarium (Desmidiales); Gomphonema and Eunotia (Pennales); Characium, Scenedesmus and Desmodesmus (Chlorococcales); Anabaena and Aphanocapsa (Nostocales and Chroococcales, respectively) were the most species-rich genera. The epiphytic community reached the highest species richness in the 15 th successional day. Regardless the substratum type, the number of species was probably related to the high concentrations of nutrients (phosphorus and nitrogen).
-(Cosmarium (Desmidiaceae, Zynemaphyceae) to periphytic phycoflora the Rosana reservoir, Paranapanema river basin, Paraná/São Paulo, Brazil). This study aimed to publish species belonging to the genus Cosmarium Corda of the periphytic community in three regions of the Rosana reservoir, southern Brazil. The samples were collected during the summer period and winter in the distinct regions to long of the axis the river-dam in the Rosana (Paranapanema River). The collected substrata, always in the littoral region and in all of the collection points, they were petioles of Eichhornia azurea Kunth. In the results were registered 48 species, distributed in fluvial, intermediary and lacustrine regions. Among these taxa, 45 were registered for the summer and 31 for the winter. Higher species richness occurred in the lacustrine region for both periods of collection. Cosmarium abbreviatum Raciborski var. minus (West & West) Krieger & Gerloff, C. granatum Brébisson ex Ralfs, C. pseudoconnatum Nordstedt, C. punctulatum Brébisson and C. quadrum Lundell var. minus Nordstedt occurred all regions were sampled in both periods. Key words: desmids, periphytic algae, taxonomy RESUMO -(Cosmarium (Desmidiaceae, Zygnemaphyceae) da ficoflórula perifítica do reservatório de Rosana, bacia do rio Paranapanema, Paraná/São Paulo, Brasil). Com este trabalho, objetivou-se divulgar espécies pertencentes ao gênero Cosmarium Corda, da comunidade perifítica de três regiões do reservatório de Rosana, Sul do Brasil. As amostras foram coletadas durante o período de verão e inverno em distintas regiões ao longo do eixo rio-barragem do reservatório. Os substratos coletados, sempre na região litorânea e em todos os pontos de coleta, foram pecíolos de Eichhornia azurea Kunth. Foram identificados 48 táxons, distribuídos nas regiões fluvial, intermediária e lacustre. Dentre estes táxons, 45 foram registrados para o período do verão e 31 para o inverno. Maior riqueza de espécies ocorreu na região lacustre para ambos os períodos de coleta. Cosmarium abbreviatum Raciborski var. minus (West & West) Krieger & Gerloff, C. granatum Brébisson ex Ralfs, C. pseudoconnatum Nordstedt, C. punctulatum Brébisson e C. quadrum Lundell var. minus Nordstedt ocorreram em todas as regiões amostradas e em ambos os períodos. Palavras-chave: algas perifíticas, desmídias, taxonomia
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