Planktonic and non-planktonic rotifers in two environments of the Upper Parana River floodplain, state of Mate Grosso do Sul, Brazil

Investigations were carried out for the composition and occurrence of rotif er taxa of different forms and sizes during two distinct hydrological perio ds, in two environments (river and fake). Two sampling stations were establ ished in open wafer of each environments. Surface samples were taken daily for 14 days. The faunistic similarity between the environments was establis hed using Jaccard's index. One hundred and fourty three taxa were identifie d The largest number of taxa was recorded in the river. Faunistic similarit y between these environments was greater during high water. The planktonic taxa predominated and the difference for the non-planktonic ones was not ma rked. Non-planktonic ta;ra predominated in the river, while both types were numerous in the fake. We observed a larger number of smaller-sized taxa in both environments (greater than or equal to 200 mu m to 600 mu m in length ). This was related to the shallowest depths and to current velocity, which moved benthic and periphytic taxa from the bottom and littoral zone into t he water column.