Água como fator limitante na distribuição das minhocas (Annelida, Oligochaeta) da Amazônia Central.

Abstract

Forty species of earthworms from Central Amazonia, distributed in 8 families and 23 genera, were classified according to their preferred habitat. This classification shows a high number (33) of species which occur only in the vicinity of water, leading one to believe that water is the limiting factor in the distribution of the species. Most species were found in only a few habitats exibiting a narrow range of ambient humidity. A few species (4), however, were found in diverse habitats with a large variation in ambient humidity (eurihygric). Experiments to test resistance to dehydration in Pontoscolex corethurus, Andiorrhinus caudatus and Meroscolex marcusi appear to confirm that water is limiting. P. corethurus, a eurihygric species, is extremely resistent to dehydration as compared to the other 2 species. Experiments under anoxia demonstrate that A. caudatus, a species of extremely humid environments, has a high resistence to anoxia in comparison with P. corethurus, which generally inhabits drier soils and is a species characteristic of "terra firme". These data allow the verification of a water deficit in the "terra firme" soils of Central Amazonia.