The benthic insect fauna of the blackwater forest stream Rio Tarumã-Mirím (Manaus, Amazonas): Patterns of population dynamics and their implications for ecosystem stability

Abstract

The annual pattern of emergence of aquatic insects with benthic larval stages of a small. Central Amazonian blackwater river is presented. This pattern is primarily a function of the annual inundation cycle (= "flood pulse": JUNK et al. 1989), but non-random variations within sampling-sites and -periods suggest that the organisms are choosing favourable micro-habitats. Comparison between the rates of benthic litter colonization (as reported previously; WALKER 1994, 1998) and emergence of adults shows, that grosso modo 90% of the litter-colonizing juveniles enter the aquatic foodweb, while the few percent of emerging adults maintain standing stock and biomass flow of this insect fauna. The data are discussed within the context of ecosystem stability.