Colonization by oligochaetes (Annelida: Clitellata) in decomposing leaves of Eichhornia azurea (SW.) Kunth (Pontederiaceae) in a neotropical lentic system

¹ Graduate Program in Entomology, Instituto Nacional de Pesquisas da Amazônia – INPA, CP 478 69011-970 Manaus, Amazonas, Brazil
² Universidade Federal de Juiz de Fora, Programa de Pós Graduação em Comportamento e Biologia Animal, Juiz de Fora, Brazil

^* Corresponding author: martinsrt@gmail.com

Received: 21 February 2011
Accepted: 6 July 2011

Abstract

The objective of the present study was to examine the colonization of oligochaetes during the decomposition of leaves of the macrophyte Eichhornia azurea in a lentic system in southeastern Brazil. The experiment was conducted between September and November 2007, with the use of 21 nylon bags measuring 15×15 cm with 2 mm mesh, each containing 10 g of dried leaves. The bags were removed from the lake after 2, 5, 8, 12, 25, 45 and 65 days. At the end of the experiment, 31.40% of the initial mass remained, and the decomposition rate was 0.018 d⁻¹. The mean density of oligochaetes during the experiment was 32.81±9.58 ind.g⁻¹ DM. The sub-families Naidinae and Pristininae accounted for 99.83% of the oligochaetes. The substrate quality influenced the colonization of E. azurea leaves, as observed from the cluster analysis by the formation of two groups based on increased density during the experiment, indicating a degradative ecological succession. During the decomposition there were changes in the community of oligochaetes, resulting from differences in the ability to exploit various food sources, with predominance of predators in the first decomposition phase and of collectors at the end of the experiment.