The influence of water and sediment properties on the occurrence of Potamocaris Dussart, 1979 (Harpacticoida) in the upper Parana River (Brazil)

In the main channel of the Upper Parana River, four sampling sites were est ablished according to the profile of the bottom. Samples were carried out m onthly from July 1993 to February 1995 with a modified Petersen grab. Four species were found at four sites: Potamocaris bifida, P. bidens, P. bidenta ta and P. tridentata. Canonical correspondence analysis indicated differenc es in the preferred microhabitats of the Potamocaris species, mainly in reg ard to sand particle size in the main river channel. Bedform stability was the most important factor affecting the abundance of this community.