The benthic litter-dwelling macrofauna of the Amazonian forest stream Tarumã-Mirím: patterns of colonization and their implications for community stability

Abstract

Between 1983 and 1988 a total of 928 litter-filled baskets (1.8 1 volume), exposed for various periods on a stream litterbank and in its vicinity, collected 2703 individuals of 122 macrofaunal species, excluding chironomids. Species abundance was analysed in relation to exposure time, annual inundation cycle, water depth and sample size. Long-term, average species packing and animal density proved to be relatively invariant and revealed non-random frequency patterns. Previous and present data indicate that these patterns are a function of regular, specific life cycles and of intra-specific, stereotype behaviour in relation to space and litter quality, among other possibilities not considered here. Potential competition for space in these communities is discussed, considering the assumption of individual random movement versus species maintenance as a function of genetically and neurophysiologically in ormed, non-random behaviour. © 1994 Kluwer Academic Publishers.