This research was carried out at the Mogi Guaçu reservoir owned by AES Tiete. Assessment of aquatic plants and water and sediment sampling were carried out in July 2001 (dry season), November 2001 (start of rainy season) and March 2002 (end of rainy season). A total of 846 water and 516 sediment analyses were performed, with 47 water and 41 sediment characteristics being evaluated. Marginal and floating species were the main weeds in the reservoir, the most outstanding being Brachiaria subquadripara, Eichornia crassipes, Polygonum lapathifolium, Panicum rivulare, Salvinia auriculata and Pistia stratiotes. Turbidity and low light transmission by water column made the growth of the submerged plants impossible. Phosphorus and nitrogen concentration both in the water and sediment was adequate to support aquatic plant growth. The occurrence of marginal and floating plants was associated with the intense process of sedimentation in the reservoir.
aquatic plants; water quality; sediments; reservoir
