In order to verify the importance of longitudinal and seasonal variations and the effect of physical and chemical water characteristics to fish species diversity we accomplished three-month samplings, between November/1999 and August/2000, in three selected points in the Jogui River and eight points in the Iguatemi River-MS. The longitudinal variation was more important than seasonal variation in determining richness and number of individuals in the Jogui River, however, evenness did not present statistically significant differences either longitudinal or seasonal. In the Jogui River 78.3% of species richness, 81.6% of number of individuals and 41.1% of evenness variation was explained by the water chemical and physical characteristics. In the Iguatemi River we did not detect longitudinal or seasonal statistically significant differences in the analyzed community descriptors nor significant influence of environmental factors.
Community ecology; fish; diversity; Iguatemi river
