Abstract
In an attempt to understand better the ecological basis of the high production generally observed in the
floodplains, a detailed and global study was conducted on the fish community of a floodplain lake in the
Amazon plain near Manaus. Community parameters were followed on a bimonthly basis, during a 27
month period (February 1986 - May 1988). The community is characterized by high values of specific
richness and diversity and by a remarkable regularity in the distribution of the specific abundances. These
parameters, and also the density and biomass of fish, vary on a seasonal and an interannual basis in
relation with the hydrology of the system. In addition, the community is distributed among the different
habitats in a heterogeneous way. Factorial analysis of correspondences show that the main source of
variability is interannual and concern mainly the most marginal habitats. The seasonal variability has been
related to the water level in the system. The results suggest that, in spite of this variability, the community
is persistent and stable.
