Rotifera community in the area impacted by a hydroelectric plant in the transition ecotone Cerrado-Brazilian Eastern Amazon

Resumo

The species richness, abundance, and biomass of the rotifer community of the Tocantins River were analyzed from a spatiotemporal perspective, in the context of environmental parameters and the phytoplankton flora. Samples of the rotifer and phytoplankton communities were collected from the surface water with plankton nets a 68 µm mesh at 20 points (10 upstream and 10 downstream) in the area of influence of the Estreito hydroelectric dam. The most frequent rotifers were Keratella americana, K. cochlearis, and Brachionus zahniseri. The rotifers Filinia camasecla, Plationus patulus machocanthus, and P. patulus foram dominantes no rainy season, enquanto Ptygura libera, Conochilus unicornis, and Trichocerca cylindrica dominaram no dry season. Microphagic rotifers predominated during the dry season, while raptorial species were more common in the rainy season in the reservoir at the sampling points closest to the dam, and near the mouths of tributaries on the river downstream from the dam. The Canonical Redundancy Analysis indicated that seasonal factors have a strong influence on the variation in the biomass of rotifers.