Macroalgal communities of nineteen stream segments from Rio das Pedras drainage basin, mid-southern region of Paraná State, southern Brazil (25º13'-25º26' S, 51º13'-51º28' W) were investigated regarding taxonomic and ecological aspects. Sixteen stream segments were visited once and three were examined monthly from April 2004 to March 2005. Thirty-six taxa were found, and Phormidium retzii (C. Agardh) Gomont (Cyanophyta) was the most widespread species, occurring in nine sampling sites (47%). Otherwise, a very high proportion of species had restrict distribution (58% of species occurred in one stream segment). Species richness in the drainage basin was relatively high, however, the species richness in each stream segment was relatively low. Species abundance had very low values, both to drainage basin and individual sampling sites. Correlation analyses revealed only few correlations among some environmental variables and the macroalgal communities' distributional patterns in the study area. Thus, the results suggest that the local variation in the environmental features define a typical macroalgal community to each sampling site.
drainage basin; ecological distribution; macroalgae; Paraná State; stream
