 This study examined the effects of various environmental factors on the Piranha River floodplain over an eight-year period. It found that the degree of connectivity between the river and the lakes, as well as the amount of pollution entering the river, had a significant influence on the physical and chemical properties of the water. Additionally, the closing of the Porto Primavera Dam in 1998 led to an increase in water transparency, which may have contributed to biotic changes in the floodplain. Finally, the study concluded that the diluted phosphorus levels in the river water during major flooding events could have negative implications for the productivity of the floodplain's aquatic life. This article was authored by M. C. Roberto, N. F. Santana, and S. M. Thommage.