Composition and abundance of Cladocera (Crustacea) assemblages associated with Eichhornia azurea (Swartz) Kunth stands in the Upper Paraná River floodplain - DOI: 10.4025/actascibiolsci.v25i1.2118

Abstract

The composition and abundance of cladocerans associated with Eichhornia azurea (Pontederiaceae) in different environments of the Upper Paraná River floodplain were achieved. Collecting was undertaken from March 1992 to February 1993, at eight stations, two river-lake floodplain systems, Baía and Ivinheima, and in the Cortado Channel, a Paraná River-associated system. Thirty-one species of cladocerans were identified. The greatest number of species and highest abundance values were registered in floodplain environments, probably due to a great number of habitats made up of aquatic macrophytes and to the high connectivity among different environments. In the Paraná system there are some great quantities of macrophytes on its banks, however a small number of cladocerans species occurs, contrastingly to the floodplain environments. This may happens due to the high speed of the river water that restricts the development of large cladoceran populations typical of the littoral region. The great number of plankton species in this system suggests that aquatic macrophytes are like a haven to these species since the vegetation greatly reduces the speed of the water current