Colonization of rocky and leaf pack substrates by benthic macroinvertebrates in a stream in Southeast Brazil

Machado de Carvalho, EmersonSanches Uieda, VirgíniaLuciana da Motta, Rosinês

A comparative analysis was conducted of the colonization by benthic macroinvertebrates of rocky and leaf pack substrates, both natural and artificial. This colonization was evaluated by season, with the objective of ascertaining the infl uence of rainfall on the rate of colonization. The total density of macroinvertebrates after 21 days of colonization was signifi cantly greater in the dry than in the wet season. When the substrate types were compared, artifi cial leaf pack substrate presented the smallest density for both seasons. In the wet season, Chironomidae, Leptohyphidae, Hydropsychidae, Elmidae, immature stages of Trichoptera, and Hydroptilidae showed a more representative density. In the dry season, Chironomidae, Baetidae and Oligochaeta were the most abundant taxa. The artifi cial rocky substrate used in this experiment was the most appropriate, due to its resemblance with natural substrate conditions in terms of the maintenance of the structural integrity of the substrate throughout the experimental period. Successional and seasonal eff ects were of great relevance, playing an important role in the colonization process. Key words: Artificial substrate. Colonization. Ecological succession. Experimental manipulation. Tropical streams.