Longitudinal variation of attributes from flagellate protozoan community in tropical streams = Varia o longitudinal dos atributos da comunidade de protozoários flagelados de riachos tropicais

This study verified the existence of longitudinal patterns in speciescomposition, richness, density and biomass of flagellate protozoan in tropical streams and investigated whether the possible zonation patterns are different between two periods of the year. For this, samplings were carried out in three regions from 10 streams, during the summer and winter. The flagellate community may be considered species-rich, because it was represented by 106 taxa, belonging to 8 orders and 1 residual group. The values of density and biomass are greater than those commonly found in other lotic environments, with mean values close to 2.3x104 cels. mL-1 and 150.8 êgC L-1. We did not observe any conspicuous and significant longitudinal pattern of the attributes from flagellates community. Only temporal variations of these attributes were verified. The Pearson Correlation evidenced that this temporal patterns was mainly driven by the nutrients availability, temperature and dissolved oxygen, since, the higher values of species richness, density and biomass were recorded during the winter, when the higher concentrations of nutrients and dissolved oxygen and lower temperatures were registered. In summary, the absence of patterns may be ascribed to the unidirectional and continuous flow from lotic environments. O presente estudo objetivou verificar a existencia de padroes longitudinais de composicao, riqueza de especies, densidade e biomassa da comunidade de protozoarios flagelados de riachos tropicais e, ainda, investigar se os possiveis padroes de zonacao sao diferentes entre dois periodos do ano. Foram realizadas coletas em tres regioes ao longo de dez riachos, durante os periodos de verao e inverno. A comunidade de protozoarios flagelados pode ser considerada bastante rica, sendo representada por 106 taxons pertencentes a oito ordens e um grupo residual. Os valores de densidade e biomassa registrados encontram-se acima dos valores comumente encontradosem outros ambientes loticos, com valores medios proximos de 2,3x104 cels. mL-1 e 150,8 êgC L-1. Nao foi verificado nenhum padrao longitudinal conspicuo e significativo dos atributos dessa comunidade. Foram verificadas apenas variacoes temporais destes atributos. As correlacoes de Pearson demonstraram que esse padrao temporal foi governado principalmente pela disponibilidade de nutrientes, temperatura e oxigenio dissolvido, visto que os maiores valores de riqueza, densidade e biomassa foram registrados no inverno, e tambem foram verificadas as maiores concentracoes de nutrientes, de oxigenio dissolvido e as menores temper