Abstract
Submerged leaf litter is the principal habitat of the aquatic fauna in nutrient-poor, acid streams and
rivers of Central Amazonia and their inundation forests. To estimate the magnitude of this habitat, the
number of leaves per area and their mean size and dry weight were determined at various sampling stations
in the different flooded forests along the Tarumã Mirím River and its headwater streams. Samples were
collected from the inregularly inundated stream valley bottoms (baixios) of the headwater streams through
the igapó, which is subject to annual immersion and emersion phases. On these occasions, I noted a heavy
load of sediments which covered the leaf litter after the water had receded. The sediment quantity per unit
area in this habitat increased with the duration of the inundation phase and reached several tons per hectare
annually in the igapó (inundation forest). These deposits include three major components: sand, clay and
organic particles (fine detritus). The possible origin of these components is briefly considered: There are
demonstrable reasons why these substantial sediment quantities have hitherto escaped observation.
